Newbie to Restore AR-7's; Solicits Advice from AR 'Jedi Council'...

[Stacy_AR-7's]

Hello all and thanx for the warm words of welcome from Tom & Don!

I'm generating an outline to organize my restoration process. It will take some time to complete, but so that I may start "putting it out there", I've posted its first two sections here. In it I will be putting forth my thoughts and aspirations regarding the project. In it, I will also be asking you good folks a lot of questions.

This may strike you as odd, but I've never joined any type of online group before and am not sure what all the protocols might be. I appologise in advance if I violate or offend - it's certainly not my intent to do either.

It seems to me, that for me to get the widest responses from my outline, and to make it easier to respond to, I ought to just cut and paste new sections into this post-a-new-topic page thing into which I am currently typing. (taking my own advice, I've done exactly thak below and it looks and reads like crap as opposed to a nice, neat, crisp, spelchekked, laser printed Word .doc, but, I guess I'll have to live with that.

Thanks again for the welcome and without further ado...

AR-7 Redo: a working outline

1: Intro

2: Woofers

3: Tweeters

4: Crossovers

5: Cabinets

6: Connections

7: Wiring

8: Miscellaneous

Section 1: Intro

Hello and thank you for your interest and taking the time to read this. My name is Stacy Robinson; I live in Marina del Rey, CA and I have a pair of vintage AR-7’s that I bought circa 1985 from a friend who lived down the dormitory hall from me in high school. My 7’s are pretty beat up and haven’t played music in about 15 years. But I remember how well they worked ‘back in the day’ and I have wanted for a long time to bring them back to life and, if not their original glory, something approximating it that makes me happy and is a personally rewarding undertaking as well.

These little speakers were beat up when I bought them and over the years have gotten worse due to neglect and dumb decisions on my part. At one point after the cabinet seals failed, they became an art project.

I always hated the walnut vinyl veneers, but you don’t buy speakers for how they look, you buy them for how they sound. And so at one point I spray-painted the cabinets and grilles with BBQ black Rustoleum. I then did my own “Jackson Pollock” spatter paint on the grilles with neon acrylics. I thought they looked pretty cool and in fact still do. I haven’t decided on whether or not I’ll keep my grilles or fabricate new ones - nothing in this project is off the table at this point.

My AR-7 restoration project currently has no timeline or budget. That may change as it elapses, but for now I’m in a planning process and I don’t want to limit myself during this phase. My objective is obviously as complete a restoration as I can muster of these (once) high quality old speakers that bring back many happy memories. However, the specifics relating to maintaining authenticity of the job are still up in the air and will include among other considerations, consensus gathered from the feedback I hope to receive from you learned folks. This is going to be a labor of love.

I try to be pretty thorough in things I do and this project (and even this outline) is no exception. Just a few days ago, I found this resource and you folks. As I work through the sections of this outline, I will write my thoughts and objectives for each component of the whole process. I will then ask my dumb questions to you. The end of each section will include my cut-and-paste of relevant info I found on this forum, any files I’ve downloaded from it and referenced within this document and also my own pictures of my project.

Again, thank you all very much for taking the time to read this and for any knowledge you are willing to share with me.

Warm regards,

Stacy C. Robinson

P.S.: For now, I’ll post just sections 1 & 2 of this outline because it will take me some time to get the whole thing completed. And there’s always a work schedule that has a nasty habit of interrupting how we’d all really like to allocate our time. So in the interest of “putting it out there”, Section 2: Woofers follows.

Section 2: Woofers

The woofers in these speakers are NOT original. According to Tom Tyson: original AR Part # 10708-1 & later # 1200001-1 were used in the AR-7’s. I removed and threw away the original woofers in about 1989 because the foam surrounds had totally disintegrated; at that time, I did not know about the possibility of re-foaming the surrounds. From that time & before, and up thru the present, I was and continue to be, an idiot.

I replaced the original 8” woofers with 8” woofers from a pair of AR Rock Partners that I had had for a year or two at that time. Interestingly, I read in one of the posts [P01] (cited at the end of this section) that the Rock Partner is a direct descendent of the AR-18 which, in turn, is a direct descendent of the AR-7. This was just dumb, blind, happy luck and a complete coincidence on my part. Thus I feel that the current set of woofers in my AR-7’s is, if not authentic, is as close (or closer) to authentic woofers for my AR-7’s as any I might buy new (or refurbished) today. I encourage and welcome any and all learned opinions.

The number codes on the back of both my woofers read “1-2100370”, followed by “863TNE”. The logo stamp is the late 80’s contemporary block A & backwards R. I haven’t been able to find any T/S parameters for these drivers. Another post [P02] (cited at the end of this section) mentioned that AR-7 OEM woofers had a free air resonance of 25 Hz, which is unheard of by today’s standards and was a significant contributing factor as to why the remarkably small cabinet size of the AR-7 produces such astounding bass response.

The AR-7 has a spec’ed cabinet volume of 0.345 cubic feet and the Rock Partners have a spec’ed cabinet volume of 0.26 cubic feet. Therefore the AR-7’s are larger internally by about 33%. AR built a special woofer just for the 7’s because the enclosure was so small, but the Rock Partners’ cabinet is even smaller and yet the woofers employed by them were used in larger, conventionally shaped AR-18 series. It’s been more than 20 years since I heard my Rock Partners play. And I bought them as car stereo speakers for a little hatchback I had at the time. We used to take them out and set them on the parking lot of where my friends and I used to hang out. We’d crank ‘em up, play Frisbee and check out the girls. They worked pretty well for cranking our tunes outside and also as my little hatchback’s stereo. But I never A/B auditioned them next to my old 7’s in a more controlled environment so I have no reference or recollection of which sounded ‘better’ (to me). It was also around that time the 7’s original woofers went out and I got rid of that car, so my Rock Partners’ woofers went into the 7’s without a second thought. At that time I was using the 7’s primarily as DPL surrounds because I had bought a monstrous pair of Klipsch Forte’s for mains.

Incidentally, (you folks may already know about this link) I found a link to an online T/S parameter calculator: http://www.webervst.com/spkrcalc/para.htm. My problem is that I don’t have access the following items the calculator requires, or I’d just try this myself: an Audio sine-wave generator, a Frequency Counter, an AC voltmeter that will read accurately down in the millivolt range, a 1000 ohm, 5% resistor, or a 10 ohm 1% resistor. And I’m not really prepared to go out buy these items (I’m restoring 1 pair of old speakers for myself, not going into the speaker restoration business). Still, if you have (or have access to) the aforementioned gear and know how to use it, this link seems like it could be a pretty valuable tool for anyone who regularly futzes around with old loudspeakers.

So my woofer options boil down to two:

Option 1: Refoam my existing 8” woofers from the Rock Partners.

Option 2: Purchase new 8” woofers from a third party.

Refoaming: Seek professional help or D.I.Y.

As I already mentioned, my gut tells me that Option 1 is the best, given the family relations between the Rock Partners, AR-18’s and AR-7’s. But again, what do you guys think? [P03] (cited at the end of this section) has found a solution for his son’s dorm room speakers, but it seem as though his trade-off concerns are price related and the fact that the speakers he’s talking about are his son’s and they’re not in his house so he won’t have to hear them.

Please derive no offence from my interpretation of your post Guest_ginshin99_. You sound like a man who knows volumes more about audio theory and engineering than I do.

Perhaps since the AR-7’s you write about are not in your house, and thus you don’t have to hear them, and they’re also your son’s speakers, and you may have less sentimental attachment to them than I to mine, for maybe those reasons, you’ve made (what are for you) acceptable trade-offs you can live with. It’s not that I can’t live with trade offs; it’s just that I want to shoot for the stars first if possible – especially in a project planning stage. If I don’t make the cut, I’ll lower my expectations when it seems there are no other viable options for my project. At least you’ve finished yours and someone is enjoying the end result; mine isn’t even started yet.

Woofer Questions:

Q1: If my current woofers do not have a free air resonance frequency of 25 Hz (& they probably don’t) how should this affect any resizing of (new) cabinets I may have to build for this project?

Q2: Does anyone happen to know the free air resonance freq of the 8” Woofer from Rock Partners? -- OR -- Given the info from this Rock Partners spec sheet, (pasted following these questions) could anyone calculate / extrapolate / guesstimate the free air resonant frequency for my woofers?

Q3: When Robert_S mentions a ’37 Woofer in the [P01] post, (cited at the end of this section) is he referring to the 1-2100370 printed on the back of my woofers?

Q4: Does anyone have a Frequency Response plot or a more detailed spec sheet for the Rock Partners? I looked through both the library and discussion forums could not find any better info than what I have re-supplied (following after these questions).

Q5: Given that I’ve never refoamed a speaker myself and that getting everything right the first time is quite important to me, I think I should leave it to a professional. What are your thoughts on the refoaming services offered by Millersound in PA and by Carl’s Custom Loudspeakers? Does anyone have any other refoaming service that they’ve used with very satisfactory results?

Q6: Are the 8” Woofers sold by AB Tech Services for $60.00 each the same as what I have now (1-2100370), or are they something different? If they’re different, are they better, worse, about the same, a good value for the money, a waste of time & money? Obviously, they will “fit”, but are they appropriate for AR-7’s?

The Rock Partners Spec Sheet I downloaded from this Forum did not copy over in my cut & paste of this outline so I've attached it to this whole post:

Post Threads Referenced in Section 2 - Woofers:

[P01]:

Robert_S: The AR Rock Partners (sometimes referred to as the AR AV-18), can perhaps be considered as the final (shape-shifted) iteration of the AR18/AR18s/AR18b/AR18LS series, with a noble lineage that can be traced back to the AR-7. They utilise very similar components (the '37 woofer and '38 tweeter) and are often sought as a source for replacement drivers for the AR18s, in particular the tweeters.

Steve: Rock Partners were basically AR18s components in the triangular cabinet.

[P02]:

Unknown (to me) Poster: The AR-7 used the new 1 1/4" cone tweeter, introduced in the AR-6 two years previously. The 7’s woofer had a free-air resonance of 25Hz (same as the 6), mounted in an enclosure of .345 cu. ft. for a system resonance of 68Hz (compared to a system resonance for the AR-6 in its larger enclosure of 56Hz). Therefore, as a result of its woofer’s lower resonance, the 7 had very nearly identical bass response to the 4x, in spite of the 7’s cabinet being markedly smaller. Incidentally, a 25Hz free-air resonance for an 8" woofer is almost unheard of today. Most 12" OEM woofers used by the major commercial speaker companies nowadays have a free air resonance of 25-30Hz. I’d hazard the guess that there is currently not a single 8" woofer used in any low-priced speaker from a mainstream manufacturer that has a resonance anywhere near as low as the 7’s. It was really something.

[P03]:

Guest_ginshin99_: AR7 is a very small speaker. It is difficult to find woofers that will work. Finally, I found MCM 55-1940 that should do well. I used a box calculation tool on the Internet to check the frequency response. F3 should be around 75 Hz with Q at 0.96. Not low but OK. The most important part is that they cost only 15.95 each and are 8 ohm.

Well, that's it for now; there's certainly more to come as I generate it (Tweeters are next). Thanks again for reading, patience, and understanding.

-SCR

P.P.S.: Since a little knowledge is a dangerous thing, you're all duely advised to give me a wide berth!

[michiganpat]

my $.02

I'd just use the rock partner woofers you have. they should be close enough in spec to the 7's woofer to work.

refoam your self. AR8" woofs are very easy, I've done both pairs of my AR18. get the boston acoustics filleted style surrounds for them. Msound sells them on ebay. they're very compliant and what you need to keep from raising the Fs of the woofers. a stiffer, generic 8" foam will typically raise the free air resonance, raising in-box Q, and giving a hump in the bass response and raising the -3db point.

no nee to shim the voice coil gap. after you clean the old foam off, glue the surround to the cone, let dry overnight. use a 30hz test tone to center the voice coil when gluing the foam to the basket. I use Aileen's tacky glue, it's a thick PVA glue like elmers. it gives sufficient tack-time to make adjustments if necessary. some kits come with more of a contact cement that isn't nearly as forgiving.

AFAIK the ABtech woofers are asian sourced replacements that fit the box. there have been no published specs to determine if they actually match the original AR performance. their 12" replacements for the 3a/10pi/11/9/etc are known to be way off as far as specs.

if I were to buy new woofers, I'd look at the EPI replacements done by Huw Powell at www.Humanspeakers.com made in the USA, and the EPI's are like the original 18's where the woofer runs full range, so they should have a nice natural roll-off. don't know if the AR7's are as simple crossover wise, or if they have a low pass filter on the woof.

[RoyC]

I'd just use the rock partner woofers you have. they should be close enough in spec to the 7's woofer to work.

I agree...The Rock Partner woofers are the best bet with the proper replacement foam surrounds.

The AR-7 crossover consists of a single capacitor in series with the tweeter.

Roy

[DON]

Painting speaker cabinets can be a good option to the original vinyl finish. I started painting one of my least favorite speakers that originally had an ugly woodgrain vinyl finish. I applied two coats of satin black plastic paint and let that harden for several days. It still scratched easily so I decided to try a coat or two of poly. After the poly dried for a few days it was very scratch resistant and looked very nice. I used regular spray cans from Home Depot. Over on the "Club Polk" forum there are threads about restoring Polk Monitor 5s and Monitor 7s. He took the vinyl off one and applied real wood veneer and they look fantastic. On one pair he took the vinyl off and painted the cabinet with several layers of black full gloss enamel until he had a "piano" finish. These are a couple of options you have. Good luck with your project and I'm sure you will get all the help you need here.

[soundminded]

Hello all and thanx for the warm words of welcome from Tom & Don!

I'm generating an outline to organize my restoration process. It will take some time to complete, but so that I may start "putting it out there", I've posted its first two sections here. In it I will be putting forth my thoughts and aspirations regarding the project. In it, I will also be asking you good folks a lot of questions.

This may strike you as odd, but I've never joined any type of online group before and am not sure what all the protocols might be. I appologise in advance if I violate or offend - it's certainly not my intent to do either.

It seems to me, that for me to get the widest responses from my outline, and to make it easier to respond to, I ought to just cut and paste new sections into this post-a-new-topic page thing into which I am currently typing. (taking my own advice, I've done exactly thak below and it looks and reads like crap as opposed to a nice, neat, crisp, spelchekked, laser printed Word .doc, but, I guess I'll have to live with that.

Thanks again for the welcome and without further ado...

AR-7 Redo: a working outline

1: Intro

2: Woofers

3: Tweeters

4: Crossovers

5: Cabinets

6: Connections

7: Wiring

8: Miscellaneous

Section 1: Intro

Hello and thank you for your interest and taking the time to read this. My name is Stacy Robinson; I live in Marina del Rey, CA and I have a pair of vintage AR-7’s that I bought circa 1985 from a friend who lived down the dormitory hall from me in high school. My 7’s are pretty beat up and haven’t played music in about 15 years. But I remember how well they worked ‘back in the day’ and I have wanted for a long time to bring them back to life and, if not their original glory, something approximating it that makes me happy and is a personally rewarding undertaking as well.

These little speakers were beat up when I bought them and over the years have gotten worse due to neglect and dumb decisions on my part. At one point after the cabinet seals failed, they became an art project.

I always hated the walnut vinyl veneers, but you don’t buy speakers for how they look, you buy them for how they sound. And so at one point I spray-painted the cabinets and grilles with BBQ black Rustoleum. I then did my own “Jackson Pollock” spatter paint on the grilles with neon acrylics. I thought they looked pretty cool and in fact still do. I haven’t decided on whether or not I’ll keep my grilles or fabricate new ones - nothing in this project is off the table at this point.

My AR-7 restoration project currently has no timeline or budget. That may change as it elapses, but for now I’m in a planning process and I don’t want to limit myself during this phase. My objective is obviously as complete a restoration as I can muster of these (once) high quality old speakers that bring back many happy memories. However, the specifics relating to maintaining authenticity of the job are still up in the air and will include among other considerations, consensus gathered from the feedback I hope to receive from you learned folks. This is going to be a labor of love.

I try to be pretty thorough in things I do and this project (and even this outline) is no exception. Just a few days ago, I found this resource and you folks. As I work through the sections of this outline, I will write my thoughts and objectives for each component of the whole process. I will then ask my dumb questions to you. The end of each section will include my cut-and-paste of relevant info I found on this forum, any files I’ve downloaded from it and referenced within this document and also my own pictures of my project.

Again, thank you all very much for taking the time to read this and for any knowledge you are willing to share with me.

Warm regards,

Stacy C. Robinson

P.S.: For now, I’ll post just sections 1 & 2 of this outline because it will take me some time to get the whole thing completed. And there’s always a work schedule that has a nasty habit of interrupting how we’d all really like to allocate our time. So in the interest of “putting it out there”, Section 2: Woofers follows.

Section 2: Woofers

The woofers in these speakers are NOT original. According to Tom Tyson: original AR Part # 10708-1 & later # 1200001-1 were used in the AR-7’s. I removed and threw away the original woofers in about 1989 because the foam surrounds had totally disintegrated; at that time, I did not know about the possibility of re-foaming the surrounds. From that time & before, and up thru the present, I was and continue to be, an idiot.

I replaced the original 8” woofers with 8” woofers from a pair of AR Rock Partners that I had had for a year or two at that time. Interestingly, I read in one of the posts [P01] (cited at the end of this section) that the Rock Partner is a direct descendent of the AR-18 which, in turn, is a direct descendent of the AR-7. This was just dumb, blind, happy luck and a complete coincidence on my part. Thus I feel that the current set of woofers in my AR-7’s is, if not authentic, is as close (or closer) to authentic woofers for my AR-7’s as any I might buy new (or refurbished) today. I encourage and welcome any and all learned opinions.

The number codes on the back of both my woofers read “1-2100370”, followed by “863TNE”. The logo stamp is the late 80’s contemporary block A & backwards R. I haven’t been able to find any T/S parameters for these drivers. Another post [P02] (cited at the end of this section) mentioned that AR-7 OEM woofers had a free air resonance of 25 Hz, which is unheard of by today’s standards and was a significant contributing factor as to why the remarkably small cabinet size of the AR-7 produces such astounding bass response.

The AR-7 has a spec’ed cabinet volume of 0.345 cubic feet and the Rock Partners have a spec’ed cabinet volume of 0.26 cubic feet. Therefore the AR-7’s are larger internally by about 33%. AR built a special woofer just for the 7’s because the enclosure was so small, but the Rock Partners’ cabinet is even smaller and yet the woofers employed by them were used in larger, conventionally shaped AR-18 series. It’s been more than 20 years since I heard my Rock Partners play. And I bought them as car stereo speakers for a little hatchback I had at the time. We used to take them out and set them on the parking lot of where my friends and I used to hang out. We’d crank ‘em up, play Frisbee and check out the girls. They worked pretty well for cranking our tunes outside and also as my little hatchback’s stereo. But I never A/B auditioned them next to my old 7’s in a more controlled environment so I have no reference or recollection of which sounded ‘better’ (to me). It was also around that time the 7’s original woofers went out and I got rid of that car, so my Rock Partners’ woofers went into the 7’s without a second thought. At that time I was using the 7’s primarily as DPL surrounds because I had bought a monstrous pair of Klipsch Forte’s for mains.

Incidentally, (you folks may already know about this link) I found a link to an online T/S parameter calculator: http://www.webervst.com/spkrcalc/para.htm. My problem is that I don’t have access the following items the calculator requires, or I’d just try this myself: an Audio sine-wave generator, a Frequency Counter, an AC voltmeter that will read accurately down in the millivolt range, a 1000 ohm, 5% resistor, or a 10 ohm 1% resistor. And I’m not really prepared to go out buy these items (I’m restoring 1 pair of old speakers for myself, not going into the speaker restoration business). Still, if you have (or have access to) the aforementioned gear and know how to use it, this link seems like it could be a pretty valuable tool for anyone who regularly futzes around with old loudspeakers.

So my woofer options boil down to two:

Option 1: Refoam my existing 8” woofers from the Rock Partners.

Option 2: Purchase new 8” woofers from a third party.

Refoaming: Seek professional help or D.I.Y.

As I already mentioned, my gut tells me that Option 1 is the best, given the family relations between the Rock Partners, AR-18’s and AR-7’s. But again, what do you guys think? [P03] (cited at the end of this section) has found a solution for his son’s dorm room speakers, but it seem as though his trade-off concerns are price related and the fact that the speakers he’s talking about are his son’s and they’re not in his house so he won’t have to hear them.

Please derive no offence from my interpretation of your post Guest_ginshin99_. You sound like a man who knows volumes more about audio theory and engineering than I do.

Perhaps since the AR-7’s you write about are not in your house, and thus you don’t have to hear them, and they’re also your son’s speakers, and you may have less sentimental attachment to them than I to mine, for maybe those reasons, you’ve made (what are for you) acceptable trade-offs you can live with. It’s not that I can’t live with trade offs; it’s just that I want to shoot for the stars first if possible – especially in a project planning stage. If I don’t make the cut, I’ll lower my expectations when it seems there are no other viable options for my project. At least you’ve finished yours and someone is enjoying the end result; mine isn’t even started yet.

Woofer Questions:

Q1: If my current woofers do not have a free air resonance frequency of 25 Hz (& they probably don’t) how should this affect any resizing of (new) cabinets I may have to build for this project?

Q2: Does anyone happen to know the free air resonance freq of the 8” Woofer from Rock Partners? -- OR -- Given the info from this Rock Partners spec sheet, (pasted following these questions) could anyone calculate / extrapolate / guesstimate the free air resonant frequency for my woofers?

Q3: When Robert_S mentions a ’37 Woofer in the [P01] post, (cited at the end of this section) is he referring to the 1-2100370 printed on the back of my woofers?

Q4: Does anyone have a Frequency Response plot or a more detailed spec sheet for the Rock Partners? I looked through both the library and discussion forums could not find any better info than what I have re-supplied (following after these questions).

Q5: Given that I’ve never refoamed a speaker myself and that getting everything right the first time is quite important to me, I think I should leave it to a professional. What are your thoughts on the refoaming services offered by Millersound in PA and by Carl’s Custom Loudspeakers? Does anyone have any other refoaming service that they’ve used with very satisfactory results?

Q6: Are the 8” Woofers sold by AB Tech Services for $60.00 each the same as what I have now (1-2100370), or are they something different? If they’re different, are they better, worse, about the same, a good value for the money, a waste of time & money? Obviously, they will “fit”, but are they appropriate for AR-7’s?

The Rock Partners Spec Sheet I downloaded from this Forum did not copy over in my cut & paste of this outline so I've attached it to this whole post:

Post Threads Referenced in Section 2 - Woofers:

[P01]:

Robert_S: The AR Rock Partners (sometimes referred to as the AR AV-18), can perhaps be considered as the final (shape-shifted) iteration of the AR18/AR18s/AR18b/AR18LS series, with a noble lineage that can be traced back to the AR-7. They utilise very similar components (the '37 woofer and '38 tweeter) and are often sought as a source for replacement drivers for the AR18s, in particular the tweeters.

Steve: Rock Partners were basically AR18s components in the triangular cabinet.

[P02]:

Unknown (to me) Poster: The AR-7 used the new 1 1/4" cone tweeter, introduced in the AR-6 two years previously. The 7’s woofer had a free-air resonance of 25Hz (same as the 6), mounted in an enclosure of .345 cu. ft. for a system resonance of 68Hz (compared to a system resonance for the AR-6 in its larger enclosure of 56Hz). Therefore, as a result of its woofer’s lower resonance, the 7 had very nearly identical bass response to the 4x, in spite of the 7’s cabinet being markedly smaller. Incidentally, a 25Hz free-air resonance for an 8" woofer is almost unheard of today. Most 12" OEM woofers used by the major commercial speaker companies nowadays have a free air resonance of 25-30Hz. I’d hazard the guess that there is currently not a single 8" woofer used in any low-priced speaker from a mainstream manufacturer that has a resonance anywhere near as low as the 7’s. It was really something.

[P03]:

Guest_ginshin99_: AR7 is a very small speaker. It is difficult to find woofers that will work. Finally, I found MCM 55-1940 that should do well. I used a box calculation tool on the Internet to check the frequency response. F3 should be around 75 Hz with Q at 0.96. Not low but OK. The most important part is that they cost only 15.95 each and are 8 ohm.

Well, that's it for now; there's certainly more to come as I generate it (Tweeters are next). Thanks again for reading, patience, and understanding.

-SCR

P.P.S.: Since a little knowledge is a dangerous thing, you're all duely advised to give me a wide berth!

http://cgi.ebay.com/2-ACOUSTIC-RESEARCH-AR-7-Speakers-Walnut-/260793828508?pt=Vintage_Electronics_R2&hash=item3cb886049c

[Stacy_AR-7's]

Hello again and thanx to “michiganpat”, “RoyC”, “Don”, and “soundminded” for your time, thoughts, knowledgable responses, and for giving enough of a hoot to talk to me! It’s definitely appreciated. Also thanx to “Tom” for for the e-bay cabinets-for-sale reference (300560579178).

I checked them out and unfortuneately, the e-bay cabinets have a third hole cut into each baffel. My baffels are pretty tore up and even if I don’t replace the whole cabinets, I’ll still have to do some work on my original baffels, because they’re missing a few t-nuts and one of the screw holes is completely gone – chipped out and the missing divot is no where to be found. Thus the woofers will never seat and seal properly. God I hate MDF and Particleboard (and have always hated since my boyhood model railroading days)! But, more on the cabinets and their concerns when I get to that section of my outline.

The e-bay AR-7’s (3cb886049c) that “soundminded” pointed me to look pretty cool and I’m thinking about them – for $50 how could I go wrong? Curiously, they don’t have any badges (at least in the seller provided pix). But, if they work (most likely they will need a refoam job) and are original, that would be a score for me to have as a reference system when my project is done; and if they don’t, I’ll have $50 worth of spare parts for what I’ve got now - might be worth it .

BTW, “soundminded”, I was checking out your Bose 901 / mylar tweeter project on the Bose page and while even the self-censored technicalities you did reveal were beyond me, the jist of your project is very compelling and I wish you all the best success with it. Definitely sounds like it would be something worth hearing. Good luck!

Early consensus among you repliers seems to agree with what my gut tells me: go with a re-foaming of my Rock Partners woofers. The jury is still out on whether or not I’ll do the re-foam or have a pro do it. Either way, “michiganpat’s” suggestion of Boston Acoustics’ filletted re-foam and “RoyC’s” concurrence of “proper replacements” is appreciated advice.

If I am understanding your process description correctly “michiganpat”, are you advising that when I attach the surrounds to the baskets that I should do so while a 30 Hz signal vibrates the cone / new foam assembly? Am I to glue a doughnut of foam (while it is motion) to a steel basket (which is at rest)??

If that’s the case, I’ve definitely got to have a real pro with real experience do this, (I’ll send them the woofs, the proper foam, pay him for his time, AND insist on the 30Hz signal) because I don’t have previous experience with this and I’m leary about trying it while both parts of the system are at rest! If I screw this up, I’m S.O.L.; I obviously can’t run out to the AR store and buy another woofer. Don’t get me wrong, I want to do it – successful completion of this sub-project would be extremely satisfying for me. It’s just that there is absolutely no margin for error.

Thanks again for your interest.

Regards,

Stacy

[RoyC]

Thanks again for your interest.

Regards,

Stacy

Stacy,

I recently completed a restoration of a pair of AR-7's, and may be able to help you out. Check your personal messages.

Roy

[soundminded]

Hello again and thanx to “michiganpat”, “RoyC”, “Don”, and “soundminded” for your time, thoughts, knowledgable responses, and for giving enough of a hoot to talk to me! It’s definitely appreciated. Also thanx to “Tom” for for the e-bay cabinets-for-sale reference (300560579178).

I checked them out and unfortuneately, the e-bay cabinets have a third hole cut into each baffel. My baffels are pretty tore up and even if I don’t replace the whole cabinets, I’ll still have to do some work on my original baffels, because they’re missing a few t-nuts and one of the screw holes is completely gone – chipped out and the missing divot is no where to be found. Thus the woofers will never seat and seal properly. God I hate MDF and Particleboard (and have always hated since my boyhood model railroading days)! But, more on the cabinets and their concerns when I get to that section of my outline.

The e-bay AR-7’s (3cb886049c) that “soundminded” pointed me to look pretty cool and I’m thinking about them – for $50 how could I go wrong? Curiously, they don’t have any badges (at least in the seller provided pix). But, if they work (most likely they will need a refoam job) and are original, that would be a score for me to have as a reference system when my project is done; and if they don’t, I’ll have $50 worth of spare parts for what I’ve got now - might be worth it .

BTW, “soundminded”, I was checking out your Bose 901 / mylar tweeter project on the Bose page and while even the self-censored technicalities you did reveal were beyond me, the jist of your project is very compelling and I wish you all the best success with it. Definitely sounds like it would be something worth hearing. Good luck!

Early consensus among you repliers seems to agree with what my gut tells me: go with a re-foaming of my Rock Partners woofers. The jury is still out on whether or not I’ll do the re-foam or have a pro do it. Either way, “michiganpat’s” suggestion of Boston Acoustics’ filletted re-foam and “RoyC’s” concurrence of “proper replacements” is appreciated advice.

If I am understanding your process description correctly “michiganpat”, are you advising that when I attach the surrounds to the baskets that I should do so while a 30 Hz signal vibrates the cone / new foam assembly? Am I to glue a doughnut of foam (while it is motion) to a steel basket (which is at rest)??

If that’s the case, I’ve definitely got to have a real pro with real experience do this, (I’ll send them the woofs, the proper foam, pay him for his time, AND insist on the 30Hz signal) because I don’t have previous experience with this and I’m leary about trying it while both parts of the system are at rest! If I screw this up, I’m S.O.L.; I obviously can’t run out to the AR store and buy another woofer. Don’t get me wrong, I want to do it – successful completion of this sub-project would be extremely satisfying for me. It’s just that there is absolutely no margin for error.

Thanks again for your interest.

Regards,

Stacy

The project you outlined will give you some serious challenges. Painting the enclosures is a matter of cosmetics, it does not impact the functionality of the speaker. Painting the grill cloth is an entirely different matter. Grill cloth is selected to be as visually opaque and as acoustically transparent as possible. Regardless of the esthetics, the fabric is intended to be an open weave with a very high percentage of space taken up by air channels between the fibers. By painting them shut, this will make the grillcloth much more opaque and is especially noticable at high frequencies. The grillcloth should be replaced. If you visit a fabric store go for a very open weave fabric. I've outlined elsewhere how I make selections in the store.

Researching the library it became evident that the woofer used in AR7 was a new design for that speaker system. The woofer/enclosure/stuffing form a carefully tuned system which in AR's case is intended to produce the deepest bass possible that has little or no frequency response peak and the least distortion for the price the speaker was intended to sell for. This was a precision device. Changes to the design by changing drivers whether you prefer the results or not will result in a speaker that is not an AR7. For better or worse it will be a different speaker. You should expect that the results will likely be unpredictable. Even carefully restored speakers will not necessarily sound the same as they did 40 years ago, we have no way to find out. This is because even samples that were kept in pristine condition aged over time due to changes in their material structures. Hopefully the tweeters are in good condition.

AR7 was intended as a relatively low cost compact speaker providing what AR felt at the time was the best tradeoff between price and performance. AR speakers like others of its type were intended for accurate reproduction of what some would call "serious music" which means classical and jazz. They are not designed for playing rock music at ear shattering levels and when used that way are often badly damaged. Take your intended use for them into consideration. Before you spend your money, consider your options and whether it is worth the cost and effort to restore them. That money might be better spent on other speakers.

[JKent]

Before you spend your money, consider your options and whether it is worth the cost and effort to restore them. That money might be better spent on other speakers.

I think Soundminded makes good points. Of course, you described this as a "labor of love" and only YOU can know what it's worth to you. But consider these points:

• As Soundminded pointed out, you MUST replace the grille cloth with appropriate, acoustically transparent material. Given your Jackson Pollock treatment of the cabinets, the best choice may be the black stretchy knit cloth. The Human Speakers website shows how to apply this. http://www.humanspeakers.com/howto/grill-cloth.htm
  
• AR-7s are relatively uncommon (not rare as in valuable, but uncommon). Soundminded provided a link to an eBay sale for look to be perfectly nice 7s. I don't know what they'll go for but most likely under 100 bucks. Maybe way under. Here's another pair: http://cgi.ebay.com/...ME:B:SS:US:1123
  
• A refoam kit for your Rock Partners woofers will be $25. Paying someone else to do the job could be 3x that price, and they're still the wrong woofers.
• Depending on your room, budget, and musical tastes there are probably better choices. The 2ax for example is physically larger, looks nice with its real wood veneer, and can handle anything you throw at it, from AC/DC to Zydeco. There were lots of these produced and they sell today for ridiculously low prices (IMHO). Other inexpensive vintage alternatives would be Large Advents, KLH Seventeens, AR 4x, Avid 100 and others. The 17 and 4x and Avids usually sell for VERY low prices. I'm not even scratching the surface here.
• You could sell the tweeters from your 7s. You could also sell the RP woofers in need of foam. Put the $ toward something else.
• If you love the paint job on your Jackson Pollock cabinets, you could use them as the basis for a new speaker project. Somewhere in these pages a member described a system built using very inexpensive clearance center drivers from Parts Express. If the speaker-building bug has bitten you, they could be a fun project. The parts are still available and for $35 you can everything you need to build the "Rompicollo": http://techtalk.part...ad.php?t=225010
  

Again, only you can assess your emotional attachment to these AR7s but from a detached, objective point of view, the expenditure of time and money to make them right does not seem to be worth it. And in the end you'll have a pair of speakers that were, as Soundminded succinctly described "AR7 was intended as a relatively low cost compact speaker providing what AR felt at the time was the best tradeoff between price and performance".

Kent

[michiganpat]

I think Soundminded makes good points. Of course, you described this as a "labor of love" and only YOU can know what it's worth to you. But consider these points:

• As Soundminded pointed out, you MUST replace the grille cloth with appropriate, acoustically transparent material. Given your Jackson Pollock treatment of the cabinets, the best choice may be the black stretchy knit cloth. The Human Speakers website shows how to apply this. http://www.humanspeakers.com/howto/grill-cloth.htm
  
• AR-7s are relatively uncommon (not rare as in valuable, but uncommon). Soundminded provided a link to an eBay sale for look to be perfectly nice 7s. I don't know what they'll go for but most likely under 100 bucks. Maybe way under. Here's another pair: http://cgi.ebay.com/...ME:B:SS:US:1123
  
• A refoam kit for your Rock Partners woofers will be $25. Paying someone else to do the job could be 3x that price, and they're still the wrong woofers.
• Depending on your room, budget, and musical tastes there are probably better choices. The 2ax for example is physically larger, looks nice with its real wood veneer, and can handle anything you throw at it, from AC/DC to Zydeco. There were lots of these produced and they sell today for ridiculously low prices (IMHO). Other inexpensive vintage alternatives would be Large Advents, KLH Seventeens, AR 4x, Avid 100 and others. The 17 and 4x and Avids usually sell for VERY low prices. I'm not even scratching the surface here.
• You could sell the tweeters from your 7s. You could also sell the RP woofers in need of foam. Put the $ toward something else.
• If you love the paint job on your Jackson Pollock cabinets, you could use them as the basis for a new speaker project. Somewhere in these pages a member described a system built using very inexpensive clearance center drivers from Parts Express. If the speaker-building bug has bitten you, they could be a fun project. The parts are still available and for $35 you can everything you need to build the "Rompicollo": http://techtalk.part...ad.php?t=225010
  

Again, only you can assess your emotional attachment to these AR7s but from a detached, objective point of view, the expenditure of time and money to make them right does not seem to be worth it. And in the end you'll have a pair of speakers that were, as Soundminded succinctly described "AR7 was intended as a relatively low cost compact speaker providing what AR felt at the time was the best tradeoff between price and performance".

Kent

a few counter points to Jkent:

1) Msound will sell just the foams (in non-kit form) for about $12-15/pr....pick up some aileen's tacky glue and give it a go. the Rock Partner woofers were designed for a similar sized enclosure, using essentially the same tweet/xover...performance wise they'll be fine, appearance wise they might be a tad "off" (IIRC the rock partners I've seen have a domed poly dustcap, vs. a flat paper dustcap)

as far as foaming directions, what works for me is 1) take the woofer out of the cabinet 2) clean all the loose foam & crumbs off...carefully use a razor blade to scrape it off 3) using the aileen's tacky glue, glue the foam surround to the cone, let sit overnight. 4) the next day, with the bare woofer hooked up to a source, apply the tacky glue to glue the surround to the basket. at low volume, play the test tone. press the the basket and surround together, if you hear any buzzing/scratching, from the voice coil hitting the pole piece, you can shift the surround to eliminate it. if you have 'em, you can then use some spring loaded clothespins to clamp the foam to the basket around the perimeter. once all the clothespins are on, you can turn off the test tone. let dry overnight, then remove the pins.

2)I own the 7's successors, the 18 (non-S)...have 'em in my living room, sound wonderful with surprising bass from such little speakers....given Roy's detailing of a single cap crossover, it sounds like the 7's and 18's are essentially identical as far as construction, only difference is styling (18's have a foam grille and a vinyl walnut cab, all drivers are rear wired, whereas early 7 tweets are front wired). if you have space limitations, these are wonderful speakers, mine go plenty loud and plenty deep in our 17x13 living room powered by a marantz 2265. this tweeter is one of my absolute favorites.

3) Johnny's Rompicello's are much larger volume wise (~.88 cubic foot vs. the 7/18's about .38 cubic foot) and probably would sound pretty poor in those cabs...besides, drivers aren't his problem....if he were repurposing the cabs, the AK indignia would be a better fit, volume wise...if the cabinets are beyond hope, I'd build new ones, matching the internal volume out of cabinet grade 3/4" plywood, personally, or increasing the volume to the AR6 or AR17 volume size, which use the same driver compliment, and reach another ~10hz lower due to the increased cabinet volume

[JKent]

3) Johnny's Rompicello's are much larger volume wise (~.88 cubic foot vs. the 7/18's about .38 cubic foot) and probably would sound pretty poor in those cabs...besides, drivers aren't his problem....if he were repurposing the cabs, the AK indignia would be a better fit, volume wise...if the cabinets are beyond hope, I'd build new ones, matching the internal volume out of cabinet grade 3/4" plywood, personally, or increasing the volume to the AR6 or AR17 volume size, which use the same driver compliment, and reach another ~10hz lower due to the increased cabinet volume

OOPS. I totally missed the cabinet size. Mea culpa.

Kent

[Stacy_AR-7's]

Wow! Responses to my questions, patience with my ignorance, and true, real passion for high quality speakers, as well as knowledge and a willingness to share it are truely incredible here! I'm grateful to all of you who have responded so far. Thank you again.

I've got sections 3 and 4 (Tweeters and Crossovers) of my outline done and am posting it here. It follows the same format as my other post, and looks just as bad because the cut-and-paste from Word looses its formatting. But here goes.

Section 3: Tweeters

As it turns out, My AR-7’s are already somewhat of “Frankensteins” and have always been since I’ve owned them. Even if all they needed was new surrounds for the original woofers, they would still not be authentic vintage AR-7’s because I discovered that the tweeters in them are not OEM AR-7 / -6 tweeters, nor are they the ferro-fluid versions found in the -18’s and Rock Partners.

My tweeters are the “morel” brand, model # MDT 28. Morel’s tweeter page (http://www.morelhifi.com/products/raw_tweeters.html) lists a table of their models and relative specs; unfortunately, the MDT 28 is not listed among the others in the table. I have written to and called the morel company to get their specs, but as of this writing I have not received a response to my inquiry. The morel MDT 28’s are between 1 1/8” to 1 ¼” silk domes and they crank: loud, crisp, clean and will handle more volume than my ears. I love these tweets and I want to keep them, even if means my AR-7’s are not authentic (but obviously, they have never been authentic while I’ve owned them).

I’ve posted some pics at the end in the hopes that someone out there might recognize them and be able to share some specs. It is curious how the labels are partially (and perhaps intentionally) peeled off the rears of both of my tweeters. All I can say is they were like this when I opened the cabinets last week and must have been installed that way prior to 1985-1986 when I bought them from my friend in high school.

As “Frankensteins” is the only way I’ve ever known these loudspeakers and I am completely fine with keeping them as such. However, I could take the tweeters from the Rock Partners and use them instead. Both systems (-7’s & the Rock Partners) cross over at 2kHz. From the posts, [P4] (cited at the end of this section) I’ve gathered that the only difference between the original AR-7 tweeter and the Rock Partners version is liquid cooling.

But were I to take the Rock Partners tweeters and put them into the –7’s cabinets, (where the Rock Partners woofers are) it would seem that I should also take the Rock Partners crossovers and use put them into the –7’s cabinets. At that point, wouldn’t it just be easier to put the woofers back into the Rock Partner cabinets, and chuck the beat up old –7 cabinets and crossovers in the trash?

I don’t want to do that; what I want to do is use as much of the components that came with my –7’s when I bought them as I can, and restore them to something approximating “very good” to “excellent” physical condition (unoriginal drivers notwithstanding). I want to make them work well, look great, and most importantly - sound as close to as impressive as I can remember and that I can manage. I’m well aware that I don’t have a “National Treasure” in my hands. But I am very much in possession of a personal treasure, and it is worth it (to me) to spend some (of my) time and (my) money to bring them back to life (for me). They will be hooked up to one of my amp’s “B” outputs and become my bedroom speakers. Hopefully, I can learn as much as possible and make some new acquaintances along the way.

Tweeter Questions:

Q1: Does anyone know anything about morel tweeters? Or the morel brand’s reputation? From their website, they seem like pretty high-end products; however, every product on its manufacturer’s website is portrayed as high-end. Why would you put out marketing materials that claimed your product was merely average? Or below average?

Q2: Does anyone know anything about the morel MDT 28 tweeters from late ‘70’s to early & mid ‘80’s? If anyone reading this is familiar with morel tweeters, might you please share with me which product(s) from their currently published tweeter specs would be the closest to the MDT 28?

Q3: Is there any difference (other than the liquid cooling) between original AR-6 / -7 1.5“ wide dispersion cone tweeters and the 1.5” liquid cooled cone tweeter used in AR-18’s and Rock Partners?

Q4: What are your thoughts on using my Rock Partners tweeters during my re-build of my -7’s? I’m probably going to stick with the morels because I love them, but the whole point of (my) posting is to ask people who know more than I do what their opinions are.

Q5: How does one clean soft dome tweeters? They are slightly sticky and have attracted some small particles over the years.

Post Threads Referenced in Section 3 - Tweeters:

[P4]

Guest_ldone_*: Is the tweeter on this classic {AR-6} unique to this model or is it used on other models, such as the AR-2, etc.

Steve F: The AR-6 was the first model to use this tweeter, but it found its way into several more. The AR-7, 8, and MST/1 all used this tweeter. After it was upgraded with ferro-fluid cooling, it was used in many subsequent 2-way models, including the very successful 18 series of models. It was, in the opinion of many, the best cone tweeter ever developed for a 2-way loudspeaker in terms of smooth FR, wide dispersion and power handling.

Johnieo: Steve: Do I assume you mean the AR-18, -18s and -18b ? I presume you are not including the 18bx and 18bxi. I thought they used an inexpensive 1" tweeter.

Steve F: Yes, the x and xi models were a different animals altogether--much larger cabinet than previous 18's and the cheap 1" tweeter instead of the excellent 1 1/4" cone.

RoyC: Is a version of this tweeter used in AR-94's? I seem to recall that the 94's tweeters looked similar to those residing in a pair of AR-6's I have awaiting restoration.

Steve F: Yes, the 93 and 94 used this tweeter also, the ferro-fluid cooled version. Also some other models, like the Rock Partners, and I'm sure a few more if we go back and look at every model.

Section 4: Crossovers

The crossovers in my little “Frankenstein” AR-7’s appear to be original (based on my visual comparison of them with pictures posted in this forum). These crossovers have always worked with my morel MDT 28 tweeters and they have worked with both the original AR-7 woofers and the Rock Partner woofers I replaced the originals with when the surrounds on the originals gave out. However, these speakers haven’t played in years; they are close to 40 years old now and so I expect that maybe individual components within each crossover system may not be up to snuff any longer, but I don’t really know how to determine whether or not that’s the case.

CAPACITORS:

One of the crossover’s capacitors (I assuming it’s the capacitor – I don’t know a capacitor from a transistor) has the following information printed on it:

SPRAGUE

AR / E / 8095

6-50VNP

34D910

7447L

The other reads the same except for the final line, which reads: 7330L.

These devices are both cylinders of the same size and are both coated with light blue plastic. Their ends are black plastic. Both are about ¾” in diameter and almost 2” long. Neither device shows signs of wear & tear, excessive heat, leakage or appears to be in otherwise poor condition. The blue coating on each is intact.

I took some time to look up capacitors on the internet and what I got in the way of explanations was too technical and contained too much additional jargon for me to really understand. It’s not that I’m incapable of understanding; it’s just that the definitions used so many additional words that I also didn’t understand so as to make explanations too esoteric for me to comprehend. If one looks up “apple” in the dictionary, it says that an apple is type of “fruit”, is usually “red”, and grows on “trees”. But if one doesn’t know what fruit is, or trees are, and has no sense of red, one then has to look up these things. One finds out that trees are either deciduous or evergreen; fruit is a type of food for other species and is also source nutrition for the next generations of apple tree seeds it contains, and red is color with a wavelength of 630 to 740 nanometers. A nanometer is 1 billionth of a meter, and a meter is 3.2808 feet. And so on. One quickly looses sight of the simple question one was trying to answer in the first place.

In this forum there are differing opinions about capacitors. Some say if they look okay, they’re probably fine. Some say you can’t go wrong by replacing them. Some say replace them if the specs are off, and to tell if the specs are off you need a Digital Multimeter (which I don’t have, & even if I did I wouldn’t know the proper setting to place it to in order to test my capacitors). I have also read that there is no exact equivalent replacement for these capacitors available, but there are some available which are “close.” And further stil,l that if you can’t find capacitors in your original value, you can replace them with two at half-value running in parallel. ????? As you can tell from my ignorant rambling I don’t have enough knowledge to discern what is close and what is not close.

A user by the name of Tom [P5] (cited below) says the capacitors in AR-7 are “6 mfd, 50V NP sized units”. Obviously that is somewhat Greek to me, but Tom’s “6 mfd, 50V NP sized” roughly coincides with the “6-50VNP” printed on each of my capacitors.

RESISTORS:

The other components in the crossovers are the white ceramic (I’m guessing here) resistors. Both display the following text:

3(Omega Symbol) 10% 10W

Both also appear to be in good condition: no cracks, warp-age, swelling, signs of excessive heat or other visible damage. My assumption is that my resistors are in as good of condition as my capacitors are. Still, it would be nice to know.

FLAT / NORMAL SWITCHES:

My switches appear to be in fair condition. The toggle levers snap into and hold either position firmly, but the metal levers are dull and perhaps lightly corroded. I am considering replacing them. Both switch bodies display the following text stamped into the brass on one side:

CARLING

MEXICO

And on the other side:

UND LAB INC LIST

6A 125 VAC

3A 250 VAC

1/4 HP 120-240 VAC

Crossover Questions:

Q1: What is the exact process for testing the capacitor values? (Please include any dial or button positions to set the digital multimeter to when doing this testing, and also please specify which ends to touch the red & black meter leads to). And since many people make and sell multimeters, what kind of relatively inexpensive digital multimeter would you recommend?

Q2: Same question as Q1, but for the resistors.

Q3: Are the flat / normal toggle switches simple on / off switches? Or are they A /B switches (meaning both positions are “On” but routing the electricity through different channels (either A or )?

Q4: What, Dear AR Jedi Masters, are your thoughts regarding swapping out the toggle switches with some shiny new ones?

Q5: In Post 6 [P6] (cited below) Rich W talks about having to replace his capacitors. Should I have to do the same, are these things “directional” and if so, how do I determine which end of the capacitor to solder in which place?

Q6: Same question as Q5, but for the resistors.

Post Threads Referenced in Section 4 - Crossovers:

[P5]:

Tom: The capacitor for the AR-7 was a 6 mfd, 50V NP sized unit.

[P6]:

Rich W: I've just completed restoring my AR-7's and I am very happy with the results. Below are some other things I would check while the cabinets of your AR-7's are open. It's helpful the have a good Digital Multimeter to check capacitor and resistor values, but if you don't, you can't go wrong by changing the caps and leaving the resistor alone (resistor values generally stay stable over time).

- Capacitors. The values of mine were off, probably from age (see my original post above). I replaced mine with Solens 6.2 uF 400v available from Parts Express. The original spec calls for a 6 uF cap, but the 6.2 will work fine with no discernable difference in sound. Cut the leads of the old caps, and solder the new ones in place. Glue to back of cabinet with GE silicon glue, rather than hot glue.

- 3 Watt resistor for tweeter level. Replace if you notice any swelling. If you do replace, do not glue to back of cabinet, as the resistor needs some air around it to cool (that's why some originals go south in the first place).

- Clean the level switch by spraying some Caig's De-oxit into the switch and toggling it back and forth to work the cleaner in. You'll have to do this from the outside, as the entire switch is encased in a plastic substance on the inside, no doubt to maintain a good acoustic seal.

- Cabinet seal. To maintain proper bass response, it is extremely important that the seal around the woofer be air-tight. Do not reuse the original foam seal, as it has already been compressed from use. You'll see a number of posts on this website suggesting different sealant types. Mortite rope caulk works good for the larger AR woofers, but for the smaller 8" woofers, I prefer Hercules "Sta Put" Plummers Putty, as it is more pliable and less likely to bend the frame of the smaller woofer. I can't stress enough the importance of a good woofer-to-cabinet seal, and I can attest from personal experience that even the smallest leak will degrade bass performance.

That's about it. As unbelieveable as it sounds, these speakers are capable of producing an output at 32 hz (sub-contra C on a church organ - an extremely low bass note), albeit at a reduced level vs. its larger AR siblings. They, along with its successor, the AR-18, are the finest small speakers I have ever heard, and IMO are far smoother and natural sounding (particularly in the lower treble region) than the highly venerated Large Advent speaker (which I once owned). Of course, the Advent surpasses the modest AR-7 in the lowest bass octave and ability the play at extremely loud levels.

[JKent]

The good news: Morel tweeters are very very good.

The bad news: They are not AR7 tweeters and, as Roy will be happy to point out, you need crossover modifications to make them work with the AR Rock Partner woofers. Of course if they sound good to you, just live with them.

If you google Morel MDT 28 you'll get a number of hits. A little history is here: http://www.audiogrou...p?t=6428&page=3 including the fact that the MDT-28 was Morel's first and still (as of 2003) best-selling tweeter and that later it was called the MDT-30 or MDT-30s.

The MDT-30s is still listed on their product page. Here is the spec sheet: http://www.morelhifi...f/mdt%2030s.pdf It has apparently been discontinued also. Here it is on the PE site: http://www.parts-exp...tnumber=277-015

More good news: You can still get voice coils: http://www.madisound.com/store/product_info.php?products_id=581

If you decide to use the Rock Partner tweeters you should probably use the RP crossover as well. There is a difference in cabinet volume (I guess) but all things considered the RP xo will be a better match than the 7 xo.

Regarding your crossover questions; the blue thing (see attached photo) is a high quality Sprague 6 microfarad (uF or MFD), 50 volt (V), non-polarized (NP) electrolytic "cap." Usually we replace old caps. I replaced the caps in my AR 7s but those blue Sprague cans are very good and may not need replacement. If they are replaced, we usually use "film" caps. The same value (6uF) but higher voltage rating. Something like this is a good choice: https://www.madisoun...products_id=756

The other gizmo is a resistor and these generally last forever. It is 3 ohms (omega symbol), 10 watts (the usual rating for speakers) and 10% tolerance (it could measure from 9 to 11 ohms).

You can test resistors with a multimeter (ohmmeter) but not capacitors. For that you need an LCR meter (which will also test resistors) but unless you plan to do a lot of this, don't bother. It's easier to just replace the caps than to remove them, test them and reinstall them, and in MOST cases you should replace any caps over 20 years old. If you use the Rock Partners crossover (xo), you should replace the caps.

Switches don't go bad (usually).

Two suggestions to make this more readable and encourage more attention:

1. Resize your photos before posting. 100K MAX is plenty
2. Try to stick to just the facts. All those "references" are distracting and just make the post look interminable. Maybe I shouldn't criticize, given the length of this reply, but usually a couple of sentences or a short paragraph make a good post.
   

Kent

[Stacy_AR-7's]

Thank you JKent! Your crossover pic looks almost exactly like mine (except for the text printed on both the capacitor and the resistor). And thanks for the vote of confidence on my MDT 28's. I checked out the links (I had prevoiusly read the history post) but I was not aware of the MDT 30 / 28 similarities, nor was I aware that replacement voice coils were available. Thanx again!

Stacy

[JKent]

My pleasure. Many people here have helped me a lot and I started out with the same level of knowledge that you have

Regarding "parallel" capacitors, take a look at this thread, Post #13, the 3rd photo: http://www.classicsp...t=0

It shows an AR2ax xo. On the right you will notice 2 yellow cylinders. Those are 3uF caps that I happened to have on hand. Notice that the wire leads are joined at either end. Thus two 3uF caps become one 6uF cap. You could also use any other combination: 2uF & 4uF, or 1uF & 5uF for example. Also, you have about a =/- 10% leeway. You could use a 6.2uF cap in place of the 6uF. 5uF caps are uncommon so if needed you can use a 4.7uF cap.

Kent

[JKent]

are you advising that when I attach the surrounds to the baskets that I should do so while a 30 Hz signal vibrates the cone / new foam assembly? Am I to glue a doughnut of foam (while it is motion) to a steel basket (which is at rest)??

If that's the case, I've definitely got to have a real pro with real experience do this, (I'll send them the woofs, the proper foam, pay him for his time, AND insist on the 30Hz signal) because I don't have previous experience with this and I'm leary about trying it while both parts of the system are at rest!

First; if you decide to do it yourself, I would not recommend the short-cuts that experienced people like Pat use. Buy the full kit and follow the instructions EXACTLY. The M_Sound site has step-by-step instructions so you can read them before deciding: http://www.citlink.net/~msound/

Second, if you opt to have a pro do the work, DON'T buy the surrounds and DON'T tell the pro how to do his job. Just ship the woofers to someone like Bill LeGall of Millersound, or to Carl's Custom Loudspeakers (who often posts here) and let him supply the materials and the expertise.

Kent

[Stacy_AR-7's]

Yeah, it's looking more and more to me like a pro should do this re-foam. I have an AR 5.5" woofer out of an Advent 622 multi-media (2.1 channel PC speaker) system that also needs a new surround. But before I act on this, I will inquire if the pro can test my crossovers and if he can, I will send them off too. Given the level of knowledge on this forum, I fully expect that whoever might wind up doing my re-foam for me will also be able to test the AR-7 crossovers and perhaps advise on any modifications needed due to the Morel MDT 28 tweeters (although my "AR-7" speakers sound awesome with the Morels (using original woofers and also using Rock Partner woofers)).

Thank you again, Kent!

Stacy

BTW: although the "Cabinet section" of my outline is not yet writen and I will post pics when I generate that section, here is a pic of one of the grilles and the more beat-up of the two cabinets. Note the missing screw-hole & t-nut assembly, the crack on the front edge along the right side of the photo, and the missing corner @ lower right, also some of the tweeter screw mounting holes are completely stripped out (of both cabs) although you can't see it because of the grey sealant material. I said it before and I'll say it again: I HATE HATE HATE MDF (I understand it's use in speaker cabinet building applications due to it's consistent density; I just don't like it). The cabs aren't "Jackson Pollocked", just the grilles. Maybe I'll fab up some new ones and keep the old ones because I think they turned out cool - even if they are no longer acousticly transparent.

scr

[Stacy_AR-7's]

P.S. Sorry! I'll resize future photos before posting. As far as references go, I'm just trying to be academic about this (although academics were never my strong suit) but if people don't like it, it'll save me some time!

-scr

[JKent]

Note the missing screw-hole & t-nut assembly, the crack on the front edge along the right side of the photo, and the missing corner @ lower right, also some of the tweeter screw mounting holes are completely stripped out (of both cabs) although you can't see it because of the grey sealant material. I said it before and I'll say it again: I HATE HATE HATE MDF (I understand it's use in speaker cabinet building applications due to it's consistent density; I just don't like it). The cabs aren't "Jackson Pollocked", just the grilles. Maybe I'll fab up some new ones and keep the old ones because I think they turned out cool - even if they are no longer acousticly transparent.

Now that I see the grilles they're not bad--those dribbles probably won't affect the sound, and they do look kinda cool. One thing to do is try listening with the grilles on and off. They may be fine.

The tweeter hole was obviously (and sloppily) enlaged to accommodate the Morel tweeter, so it may not be possible to install an original AR.

As for the MDF chunks--both for the T-nuts and the corner--you might try the QuickWood epoxy "stick" found in hardware stores, Home Despot etc. Here's a video:

It can be used to attached new T-nuts, fill voids and build up the corner. Easy to work with and hard as a rock when it cures. Not sure about that crack--maybe force some regular 2-part epoxy in there. Use masking tape to seal the ends so it doesn't ooze out. After all the patching is done you can sand and paint or apply whatever you like on the outside.

btw—if you’re going to the hardware store for Quickwood, T-nuts etc, get some Duct Seal. It comes in a “brick” and is WAY more than enough to do several pair of speakers. Costs about 3 bucks. So remove the old “mortite” caulk on there. http://www.amazon.co...JJJ18XDHTGAC0B8

Oh, and for future reference--no need to pry the crossover board out. You can leave it all in place and work on it while it's still inside the cabinet.

[Stacy_AR-7's]

Thanx for the tips!

When you say "Mortite" are you talking about the grey stuff in my picture? That stuff is sticky and strikes me like a 3M product (I think it's called indoor/outdoor stucco tape). It's sticky on both sides and comes on a roll with a red plastic backing that is a royal pain in the rear to peel off if you've just clipped your fingernails.

The crossover board on the cabinet in the photo has been dislodged from the cabinet for years. If you look really closely at the photo, you can see that there is a semi-transparent ring of some kind of dried goop / glue around the hole in the rear of cabinet from which the terminals and flat / normal switch protrude. This crosover board became dislodged a long time ago and consequently I stopped using these speakers due to the lack of seal on the rear of the cabinet. Always thought I'd get around to just fixing that - oh well. Either these speakers' previous owner or his brother tried to re-glue and re-seal the cabinet with whatever might have been on hand at the time. That seal was intact when I bought them and disintegrated a few years later.

Since one crosover board was alread dis-lodged when I tore these apart last week, I thought "screw it" and pried the other one out so I could check the words written on the crossover components without having to twist and wrench 40 year old capacitor and resistor leads.

scr

[michiganpat]

as jkent stated, looks like the rock partner driver won't work without replacing the front baffle after the morel modifications.

looking at the morel MDT30 specs, it looks like it would match up pretty good with the AR woofer....I'd be a little hesitant to run it with a first order crossover like the original (6db/octave slope), I'd probably change it to second order (12db/octave), plugging some values in an online calculator for a 2000hz Linkwitz-Riley crossover (where theoretically the crossover frequency response is is "flat", vs. a butterworth crossover, where there's a +3db bump at the crossover), it returns values of 4.98 uf for the cap in series, and 1.27mh for the paralleled inductor...

only other issue with the morels is their sensitivity is rated at 90db/1w/1m, wheras I believe most of the AR7/18 variants were rated at 86db/1w/1m sensitivity, so the tweeter will be 4db louder, making the speakers "brighter" than originally designed. running them in the -3db switch position will get them much closer to the original balance between woof and tweet, or you could just custom wire in an attenuation circuit, again using an online calculator, for a nominal 8 ohm impedance, 4db of attenuation would be a 3ohm resistor in series and a 14 ohm resistor in parallel to the tweet.

those cabinets look very rough. for the broken out part of the woofer, and for all the woofer mounting locations, I'd get some scraps of 1/2" thick wood, put the t-nuts in them, and then glue them to the back of the baffle. the broken out chunk could then be filled with rope caulk/mortite, or with bondo or wood putty for the acoustical seal.

personally I'd get some marine grade plywood and make new ones. if you like the height and width of the 7, you could increase the depth to get more volume in the cabinet. the more volume, the more bass you'll get. to compare, the AR17 and 18 use identical components, but the 17's cabinet is .67 cubic feet vs. the 18's .35, and it's -3db cutoff is 50hz, vs. the 18's 62hz.

http://www.classicspeakerpages.net/library/acoustic_research/add_series_1975-1978/add_series_brochures/ar_truth_in_listening_broch/ar_truth_in_listening_broch_15.html

[JKent]

All very good advice Pat, but I think you'll have to draw a picture (quite literally) for Stacy. He's described himself as a total noob who doesn't know the difference between a non-polar cap and a baseball cap (not a criticism at all--I'm only 1/2 step ahead of him ).

If you are comfortable drawing up a theoretical xo long-distance, a drawing and a shopping list would certainly help Stacy.

Of course that won't be needed if he makes a new baffle and uses the Rock Partner tweeters but he seems to want to keep the Morels. And cutting the holes in a new baffle is nigh impossible without a router and a circle jig.

Kent

[Stacy_AR-7's]

“Michiganpat”, “JKent”: you guys friggin’ rock! The broken record repeats: Thanx again!

My outline continues…

Section 5: Cabinets

I will build new cabinets. This is an interesting page about “DIY” speaker cabinets: http://www.popularmechanics.com/technology/how-to/tips/4274625 The architecture of the author’s cabinets is different than my own ideas (up until this point). I had assumed that I would try to find a kind of MDF laminated with a real wood veneer that I would ultimately stain and seal. And I would make mitered butt joints just as my AR-7 cabinets are constructed. I consider myself pretty handy with basic tools, but I’m no “Norm Abrams”. There is something to be said for the author’s simple butt-joints and veneer “skinning” after construction.

The problems I can see with melding his approach to my pre-conceived notions are two-fold.

1: His cabinets use a whole-front fascia; this hides the front edge of his butt-joints; whereas I would like to “countersink” my grilles flush with the front edges of each side, just as my old cabinets are. Thus, I will somehow have to veneer the forward edge and internal lip of each of the cabinet’s sides, again, just as my cabinets are.

2: It is hard to tell from the small, low-rez pics on the page how his corners and edges appear. Since a veneer is - by definition - thin, the edges where the veneers butt up against each other will also be quite thin, but I still don’t want to see any edging at these joints; the look of my new cabinets should be contiguous grain from one side to the next to the next, etc., as though Norm Abrams himself made precision mitered butt joints cut from the same plank of wood.

I also checked out the author’s link to the veneer company he used for his project: http://www.veneers.com/ On their site, I found the perfect look for what I want at http://www.veneers.com/list_veneers.htm?3-1-Dark It’s the one called “Ebony, Quartered”. A sample pic from their site is attached at the end of my post.

I will have to investigate their products more thoroughly to get a sense of veneer thickness and how adjoining edges will appear in a final product. The author cut his veneers with a matte knife and a T-square, but from the pics and his description of using a router with a flush bit to trim his edges, it doesn’t sound to me as though he miter-cut his veneers (again, it is hard to tell from the small, low-rez pics on the page how his corners and edges appear).

If I change the cabinet (L & W) dims, (to go a little bigger) I’ll obviously need to make new grilles too. Or if I just increase the depth, as “michiganpat” suggested, I’ll be able to reuse my old “Jackson Pollocks”. I could go a little bigger on new cabs, but I don’t want to go too big. My end result of this project should still be a pair of “Bookshelf” speakers.

Doing searches for DIY speaker cabinets brings tons of returns. At one listed here, http://www.diyaudioandvideo.com/FAQ/Build/ its author made mention of rounding all the corners to avoid noise spikes. “Another way to cut down on noise spikes on a rectangular box is to round all the edges of the box.” It’s in the fourth paragraph up from the bottom. AR speakers are pretty damn rectangular (LST & LST2 notwithstanding) and I can’t say as I recall one mention of noise spikes anywhere in this forum. Aren’t AR’s known for their flatness? Although I must admit, I have noticed that a lot of newer loudspeakers out there (both DIY kits & fully assembled) have rounded corners; I just thought is was a trend in appearance.

Just for reference, my -7’s serial #’s are 030091, for the worse of the two cabinets, and ‘50256’ for the better one. Curious how one s/n is 6-digit while the ‘newer’ one is only a 5-digit #.

Cabinet Questions:

Q1: Is there any “Golden-Ratio”, etc. (of L to W to D) in acoustic terms that I ought to factor into new cabinet dims?

Q2: Regarding cabinet volume without respect to LxWxD… “michiganpat’s recent post above leads me to believe simply that “more is better”, but should I target a specific volume for my new cabs? Are there specific volumes or volume ranges to stay away from due to some acoustical property of which I am currently unaware?

Q3: My cabs are ½” thick on all faces. Is there a benefit increasing thickness to 5/8”, or ¾” or 1”?

Q4: Has anyone out there worked with veneers and skinning or re-skinning speaker cabinets that accommodate “countersunk” grilles? If so, how did your corners and edges turn out? What are your impressions of the veneering process in general? Is it difficult?

Q5: What do you folks recommend for internally sealing the adjoining new cabinet pieces?

Q6: Is there anything to this “rounding cabinet corners to avoid noise spikes”?

Section 6: Connections

Since in all likelihood I’ll be building new cabinets, I will need to make new terminal points. My thought was to get a “pair of D-Cups” like the top ones on this page: https://www.madisound.com/store/index.php?cPath=404_120 I would have to drill out an opening in each to accept the Flat / Normal switch. (I do so very much love “pairs of D-Cups”, but that’s a topic for another portion of the Internet entirely!)

Any thoughts?

Section 7: Wiring

The internal wiring of my –7’s (I shouldn’t even call them “-7’s” anymore) is 18 AWG stranded silver. If I’m doing all this, I am certainly going to rewire the guts.

This article http://www.roger-russell.com/wire/wire.htm#gordongow makes for interesting reading if anyone is “in the market” for new speaker wire. If regular “line cord” is good enough for the President of Macintosh, it’s certainly going to be good enough for me.

Accordingly, I recently bought a 500’ spool of burial-rated, low-voltage, 10/2 stranded-copper outdoor garden lighting wire for new speaker connections throughout. I need a total of nine 50’ leads (5 for the home theater (Klipsch Quintet Micro), 2 for my Klipsch Forte mains, and two for these “AR-7 Frankensteins”).

Q1: Should (or could) I go with heavier AWG internally?

Q2: Should I stick with stranded silver internally? Or is stranded copper “just as good”?

Section 8: Miscellaneous

STUFFING:

I saved the yellow fiberglass stuffing (in separate bags) when I disassembled my –7’s. The cabs were well packed and full. Therefore, I have enough stuffing on hand to fill new cabinets of the same internal volume, but if I go bigger on the cabinets, I’ll need to augment my existing supply.

The stuffing’s “nesting divots” into which the woofers’ backs seated were pretty well defined. However, now that I have removed and bagged all the stuffing, that natural recess will be gone when I re-stuff the new cabinets.

There was some curious and perhaps moth-eaten fabric folded into the mix of insulation such that it appeared to be “just more stuffing”. I haven’t separated it out; it’s still mixed in with the insulation in both storage bags. After culling through this forum, I can recall reading somewhere that a safety material is used to prevent chunks of stuffing from falling into the backsides of the drivers, and it now occurs to me that perhaps that moth-eaten material may at one time have served the driver protection purpose, but as of my dissection, it was just more internal fodder.

Q1: Can I just get a scrap of Owens-Corning “Pink Panther-type” insulation, shred it and add it to the mix? Or should I completely replace what’s there with “all the same” kind / color?

Q2: What is a good material to use to protect the back of my drivers from stray insulation chunks which may over time fall into their working mechanisms? Would something like a scrap of burlap work?

DRIVER SEATING AND SEALING:

When I get the new cabinets fabricated and finished, I’ll drill out pilot holes and use machine screws and T-nuts to fasten my drivers to the baffles. It seems that there is a very wide range of acceptable sealant materials for between the baskets and baffles.

I thought of using a very sticky, very pliable petro-chemical product called “Butyl” because it comes in a nice, neat 3/8” rope rolled up with a strip of waxed paper between layers. As long as it’s not too hot, the butyl will be very easy to apply. Although in 15 years, when my woofs are due for another re-foam, getting butyl off the backs of basket rings will be another story entirely.

In the entertainment industry, we in the Art Department use miles of butyl for a multitude of different quickly-sticking-one-thing-to-another, non-permanent applications which can quickly be re-set for a different camera angle. I buy mine from my favorite Hollywood expendables shop. If anyone is interested, here’s a link: http://setstuffrentals.com/proddetail.php?prod=2714&cat=78

Any thoughts on using other products?

Well, that’s about it for my outline. Thank you all for:

Your interest thus far in the pre-planning stage of my little project!

Your patience with my dumb questions!

Your good manners!

Your insight, knowledge, experience, advice, opinions, and thoughts!

And most importantly, for just being out there and loving old AR speakers!

In the name of just seeing what’s out there, I’m off to Home Depot to check out their version of high-grade plywood, MDF, (naked and pre-veneered (if available)) and maybe some conduit options for 9 channels worth of heavily insulated 10/2 garden wire. I’m sure I’ll be back to the forum in soon.

-scr

[soundminded]

“Michiganpat”, “JKent”: you guys friggin’ rock! The broken record repeats: Thanx again!

My outline continues…

Section 5: Cabinets

I will build new cabinets. This is an interesting page about “DIY” speaker cabinets: http://www.popularmechanics.com/technology/how-to/tips/4274625 The architecture of the author’s cabinets is different than my own ideas (up until this point). I had assumed that I would try to find a kind of MDF laminated with a real wood veneer that I would ultimately stain and seal. And I would make mitered butt joints just as my AR-7 cabinets are constructed. I consider myself pretty handy with basic tools, but I’m no “Norm Abrams”. There is something to be said for the author’s simple butt-joints and veneer “skinning” after construction.

The problems I can see with melding his approach to my pre-conceived notions are two-fold.

1: His cabinets use a whole-front fascia; this hides the front edge of his butt-joints; whereas I would like to “countersink” my grilles flush with the front edges of each side, just as my old cabinets are. Thus, I will somehow have to veneer the forward edge and internal lip of each of the cabinet’s sides, again, just as my cabinets are.

2: It is hard to tell from the small, low-rez pics on the page how his corners and edges appear. Since a veneer is - by definition - thin, the edges where the veneers butt up against each other will also be quite thin, but I still don’t want to see any edging at these joints; the look of my new cabinets should be contiguous grain from one side to the next to the next, etc., as though Norm Abrams himself made precision mitered butt joints cut from the same plank of wood.

I also checked out the author’s link to the veneer company he used for his project: http://www.veneers.com/ On their site, I found the perfect look for what I want at http://www.veneers.com/list_veneers.htm?3-1-Dark It’s the one called “Ebony, Quartered”. A sample pic from their site is attached at the end of my post.

I will have to investigate their products more thoroughly to get a sense of veneer thickness and how adjoining edges will appear in a final product. The author cut his veneers with a matte knife and a T-square, but from the pics and his description of using a router with a flush bit to trim his edges, it doesn’t sound to me as though he miter-cut his veneers (again, it is hard to tell from the small, low-rez pics on the page how his corners and edges appear).

If I change the cabinet (L & W) dims, (to go a little bigger) I’ll obviously need to make new grilles too. Or if I just increase the depth, as “michiganpat” suggested, I’ll be able to reuse my old “Jackson Pollocks”. I could go a little bigger on new cabs, but I don’t want to go too big. My end result of this project should still be a pair of “Bookshelf” speakers.

Doing searches for DIY speaker cabinets brings tons of returns. At one listed here, http://www.diyaudioandvideo.com/FAQ/Build/ its author made mention of rounding all the corners to avoid noise spikes. “Another way to cut down on noise spikes on a rectangular box is to round all the edges of the box.” It’s in the fourth paragraph up from the bottom. AR speakers are pretty damn rectangular (LST & LST2 notwithstanding) and I can’t say as I recall one mention of noise spikes anywhere in this forum. Aren’t AR’s known for their flatness? Although I must admit, I have noticed that a lot of newer loudspeakers out there (both DIY kits & fully assembled) have rounded corners; I just thought is was a trend in appearance.

Just for reference, my -7’s serial #’s are 030091, for the worse of the two cabinets, and ‘50256’ for the better one. Curious how one s/n is 6-digit while the ‘newer’ one is only a 5-digit #.

Cabinet Questions:

Q1: Is there any “Golden-Ratio”, etc. (of L to W to D) in acoustic terms that I ought to factor into new cabinet dims?

Q2: Regarding cabinet volume without respect to LxWxD… “michiganpat’s recent post above leads me to believe simply that “more is better”, but should I target a specific volume for my new cabs? Are there specific volumes or volume ranges to stay away from due to some acoustical property of which I am currently unaware?

Q3: My cabs are ½” thick on all faces. Is there a benefit increasing thickness to 5/8”, or ¾” or 1”?

Q4: Has anyone out there worked with veneers and skinning or re-skinning speaker cabinets that accommodate “countersunk” grilles? If so, how did your corners and edges turn out? What are your impressions of the veneering process in general? Is it difficult?

Q5: What do you folks recommend for internally sealing the adjoining new cabinet pieces?

Q6: Is there anything to this “rounding cabinet corners to avoid noise spikes”?

Section 6: Connections

Since in all likelihood I’ll be building new cabinets, I will need to make new terminal points. My thought was to get a “pair of D-Cups” like the top ones on this page: https://www.madisound.com/store/index.php?cPath=404_120 I would have to drill out an opening in each to accept the Flat / Normal switch. (I do so very much love “pairs of D-Cups”, but that’s a topic for another portion of the Internet entirely!)

Any thoughts?

Section 7: Wiring

The internal wiring of my –7’s (I shouldn’t even call them “-7’s” anymore) is 18 AWG stranded silver. If I’m doing all this, I am certainly going to rewire the guts.

This article http://www.roger-russell.com/wire/wire.htm#gordongow makes for interesting reading if anyone is “in the market” for new speaker wire. If regular “line cord” is good enough for the President of Macintosh, it’s certainly going to be good enough for me.

Accordingly, I recently bought a 500’ spool of burial-rated, low-voltage, 10/2 stranded-copper outdoor garden lighting wire for new speaker connections throughout. I need a total of nine 50’ leads (5 for the home theater (Klipsch Quintet Micro), 2 for my Klipsch Forte mains, and two for these “AR-7 Frankensteins”).

Q1: Should (or could) I go with heavier AWG internally?

Q2: Should I stick with stranded silver internally? Or is stranded copper “just as good”?

Section 8: Miscellaneous

STUFFING:

I saved the yellow fiberglass stuffing (in separate bags) when I disassembled my –7’s. The cabs were well packed and full. Therefore, I have enough stuffing on hand to fill new cabinets of the same internal volume, but if I go bigger on the cabinets, I’ll need to augment my existing supply.

The stuffing’s “nesting divots” into which the woofers’ backs seated were pretty well defined. However, now that I have removed and bagged all the stuffing, that natural recess will be gone when I re-stuff the new cabinets.

There was some curious and perhaps moth-eaten fabric folded into the mix of insulation such that it appeared to be “just more stuffing”. I haven’t separated it out; it’s still mixed in with the insulation in both storage bags. After culling through this forum, I can recall reading somewhere that a safety material is used to prevent chunks of stuffing from falling into the backsides of the drivers, and it now occurs to me that perhaps that moth-eaten material may at one time have served the driver protection purpose, but as of my dissection, it was just more internal fodder.

Q1: Can I just get a scrap of Owens-Corning “Pink Panther-type” insulation, shred it and add it to the mix? Or should I completely replace what’s there with “all the same” kind / color?

Q2: What is a good material to use to protect the back of my drivers from stray insulation chunks which may over time fall into their working mechanisms? Would something like a scrap of burlap work?

DRIVER SEATING AND SEALING:

When I get the new cabinets fabricated and finished, I’ll drill out pilot holes and use machine screws and T-nuts to fasten my drivers to the baffles. It seems that there is a very wide range of acceptable sealant materials for between the baskets and baffles.

I thought of using a very sticky, very pliable petro-chemical product called “Butyl” because it comes in a nice, neat 3/8” rope rolled up with a strip of waxed paper between layers. As long as it’s not too hot, the butyl will be very easy to apply. Although in 15 years, when my woofs are due for another re-foam, getting butyl off the backs of basket rings will be another story entirely.

In the entertainment industry, we in the Art Department use miles of butyl for a multitude of different quickly-sticking-one-thing-to-another, non-permanent applications which can quickly be re-set for a different camera angle. I buy mine from my favorite Hollywood expendables shop. If anyone is interested, here’s a link: http://setstuffrentals.com/proddetail.php?prod=2714&cat=78

Any thoughts on using other products?

Well, that’s about it for my outline. Thank you all for:

Your interest thus far in the pre-planning stage of my little project!

Your patience with my dumb questions!

Your good manners!

Your insight, knowledge, experience, advice, opinions, and thoughts!

And most importantly, for just being out there and loving old AR speakers!

In the name of just seeing what’s out there, I’m off to Home Depot to check out their version of high-grade plywood, MDF, (naked and pre-veneered (if available)) and maybe some conduit options for 9 channels worth of heavily insulated 10/2 garden wire. I’m sure I’ll be back to the forum in soon.

-scr

Let me see if I understand this. Different woofers, different tweeters, and a different cabinet. Could you remind me what the end product will have in common with AR7? I seem to have forgotten somewhere along the way.

[Stacy_AR-7's]

Let me see if I understand this. Different woofers, different tweeters, and a different cabinet. Could you remind me what the end product will have in common with AR7? I seem to have forgotten somewhere along the way.

Most unfortuneately, little to nothing.

-scr