AR-5 Box Stuffing

[Analogman]

Hi,

My first post here and of course, it's a question.

I am in the middle of a refurb on a pair of "5"s and need to know if the quantity of box stuffing was 32oz. as it was with the "2ax".

Your help is much appreciated.

Kind regards,

Craig

[RoyC]

Hi,

My first post here and of course, it's a question.

I am in the middle of a refurb on a pair of "5"s and need to know if the quantity of box stuffing was 32oz. as it was with the "2ax".

Your help is much appreciated.

Kind regards,

Craig

Welcome Craig,

The AR-5 cabinet was stuffed with approximately 20 to 22oz of wadded yellow fiberglass. The 2ax only used the higher amount in cabinets equipped with the earlier cloth surround woofer. The AR-5 and later 2ax essentially shared the same foam surround woofer, as well as stuffing type and amount.

Roy

[Analogman]

Welcome Craig,

The AR-5 cabinet was stuffed with approximately 20 to 22oz of wadded yellow fiberglass. The 2ax only used the higher amount in cabinets equipped with the earlier cloth surround woofer. The AR-5 and later 2ax essentially shared the same foam surround woofer, as well as stuffing type and amount.

Roy

Thank you Roy.

I segregated and saved the original material from my cabs, but had planned to go back with polyfil. It is my opinion that the tiny glass fibers help contribute to pot drop outs (like throwing dirt in them). I have a real problem with fiberglass, I worked in the boat industry for a brief time.

Anyway, I am aware that purists will disagree with what I plan to install, but I'd like to ask your opinion, Roy. What, if any, adjustments would you make to this amount if you were to find yourself with no other option other than the polyfil?

I may break down and go with the glass, but I'm sure leaning against it.

Thank you again for your rapid response.

Hope this finds you well,

Craig

[RoyC]

Thank you Roy.

I segregated and saved the original material from my cabs, but had planned to go back with polyfil. It is my opinion that the tiny glass fibers help contribute to pot drop outs (like throwing dirt in them). I have a real problem with fiberglass, I worked in the boat industry for a brief time.

Anyway, I am aware that purists will disagree with what I plan to install, but I'd like to ask your opinion, Roy. What, if any, adjustments would you make to this amount if you were to find yourself with no other option other than the polyfil?

I may break down and go with the glass, but I'm sure leaning against it.

Thank you again for your rapid response.

Hope this finds you well,

Craig

Well, the yellow fiberglass in the 5 is not as bad to work with as AR's original brittle rockwool type of stuffing, nor have I found it to be a problem for well cleaned pots or new l-pads.

If you must use a different material, Acousta-Stuf is not a bad bet. If you want to try ordinary polyester, Walmart's inexpensive "Morning Glory" is as good as any. I have even mixed the two with good results. In any case, it seems that a 20%+/- reduction by weight compared to the original fiberglass works best. In other words, 16oz of poly should put you in the ballpark.

Roy

[Analogman]

Well, the yellow fiberglass in the 5 is not as bad to work with as AR's original brittle rockwool type of stuffing, nor have I found it to be a problem for well cleaned pots or new l-pads.

If you must use a different material, Acousta-Stuf is not a bad bet. If you want to try ordinary polyester, Walmart's inexpensive "Morning Glory" is as good as any. I have even mixed the two with good results. In any case, it seems that a 20%+/- reduction by weight compared to the original fiberglass works best. In other words, 16oz of poly should put you in the ballpark.

Roy

Thank you once again. I seemed to recall 16oz. as the suggested amount of non-original material from a pair of "2-ax"s I did for my Daughter.

I will retain the original material for the inevitable owner of this particular pair in case they want to re-install it. The polyfil will facilitate a cleaner in and out scenario if upgrades or mods are eventually done to these.

Regards,

Craig

[RoyC]

The polyfil will facilitate a cleaner in and out scenario if upgrades or mods are eventually done to these.

I agree, that is an advantage of using the non-fiberglass material. Also, if you intend to use putty, don't use it on the woofer until you settle on a final configuration. I've increasingly been using the foam gasket tape sold by Parts Express for easier removal of the woofer.

You may have to experiment a bit to get the right amount and placement of polyfil in your cabinets. I found the main drawback to using 100% poly is that it's fluffy/expanding nature makes it hard to vary placement within the cabinet. The proximity of the stuffing to the woofer has an effect on the character of the lower midrange and upper bass. Acousta-Stuf is denser and easier to place in varied ways.

Good luck with the project, and keep us posted...

Roy

[Analogman]

I agree, that is an advantage of using the non-fiberglass material. Also, if you intend to use putty, don't use it on the woofer until you settle on a final configuration. I've increasingly been using the foam gasket tape sold by Parts Express for easier removal of the woofer.

You may have to experiment a bit to get the right amount and placement of polyfil in your cabinets. I found the main drawback to using 100% poly is that it's fluffy/expanding nature makes it hard to vary placement within the cabinet. The proximity of the stuffing to the woofer has an effect on the character of the lower midrange and upper bass. Acousta-Stuf is denser and easier to place in varied ways.

Good luck with the project, and keep us posted...

Roy

Well, I've got them up and running, the shake down cruise. I used the 16oz. of polyester as discussed. Washed, sun dried and re-installed the old foam rings for the woofers, so far so good for now.

Set them up temporarily with a little Pioneer SX-780 I just went through, modest but functional, I'll try tubes later.......

Impressions?

These are some of the most Musical sounding speakers I've heard in a LONG time (and I've had and still have some damn fine ones, including some 2-ax(s). As I type this I have Jon Faddis on in the other room, moderately high volume. The house is filled with some of the most euphonic sound I've had in a while.

Only negative: the bass is so prodigious that I have a cabinet buzz somewhere in the crossover or terminal cup area on one box. Funny thing is the Red Hot Chili Peppers didn't bring this out but the instrumental piano track at the end of Tom Petty's "She's The One" is what did it. Sh&t!

I hate re-dos, but in this case I don't mind, I don't mind at all.

I've finally heard for the first time what y'all have known all along; a good friend of mine had some "3"s and they were nothing like this (but they were ragged and not well cared for or even properly cleaned up, still.......)

These "5"s have made me a believer.

Thank you for your input. More later.

Craig

[soundminded]

I agree, that is an advantage of using the non-fiberglass material. Also, if you intend to use putty, don't use it on the woofer until you settle on a final configuration. I've increasingly been using the foam gasket tape sold by Parts Express for easier removal of the woofer.

You may have to experiment a bit to get the right amount and placement of polyfil in your cabinets. I found the main drawback to using 100% poly is that it's fluffy/expanding nature makes it hard to vary placement within the cabinet. The proximity of the stuffing to the woofer has an effect on the character of the lower midrange and upper bass. Acousta-Stuf is denser and easier to place in varied ways.

Good luck with the project, and keep us posted...

Roy

Sorry to have to disagree. In an acoustic suspenson speaker system, the precise nature of the stuffing is a critical element in the system "tuning." As I analyze it, the system is easily understood by applying the principles of Newton's second law of motion as it applies to forced oscillation. This can be found in any college text on mechanics-dynamics or college physics along with its approximate solution (Villchur's thermodynamic analysis while not wrong was not really applicable. Thermodynamics tells you about conversion between mechanical and heat energy between end states, not about motion between those states. In other words, he got the right answer for the wrong reason.) The equation relates three variables, moving mass, damping, and springiness to frequency response. When these three variables are adjusted properly, the frequency response will have its greatest low end extension without a resonant bump. In the equations, this is called critical damping where the system coefficient Q is .707. This is the goal of AR acoustic suspension woofer design. It's also the goal of tuning the suspension of an automobile to which it is directly analogous among the many other applications of this equation.

The role the stuffing plays in this is that it creates a velocity related frictional loss (B in the equation) as the cone works to push and pull air through the space between the fibers. The space not displaced by the fibers is air which controls the system's springiness (K.) By changing the material or the way it is packed, you change both of these variables and detune the system. In the original development, the size of the box and the amount of the stuffing was undoubtedly determined by trial and error. If the rockwool stuffing is a problem because of sulfur compounds, one way around it is to create a vapor barrier between it and the pots. This can be done by applying an impermiable material like Saran Wrap film over the pots and adhering them to the wood around the pots with GE silicone caulking. When cured this should form a vapor tight barrier which can easily be removed and replaced later on should further servicing be required.

[Mexicomike]

As far as sealing controls - I'm no speaker expert but I have a lot of experience with automotive and boat electrical systems. My experience is that trying to seal moisture out ALSO seals moisture in. There are many video-screen type products sold in the marine world that are sealed to prevent moisture from entering and the first time you use them in the sun, they fog up because of the moisture in them that cannot escape. You have to open them up to let it evaporate.

I know, a speaker is not normally in a moist environment but it can be in a high humidity environment. I would suggest merely filling the pots with dielectric grease that's what you would do on automotive/marine electrical systems. But again I'm no speaker expert and I'll certainly tell folks to defer to the speaker experts.

[RoyC]

Sorry to have to disagree. In an acoustic suspenson speaker system, the precise nature of the stuffing is a critical element in the system "tuning."

...which is why I mentioned differences between amounts and types of material, as well as placement within the cabinet.

A number of us have shared many notes on cabinet damping material behavior as it relates to the AR-5/3a era ARs. Along with listening tests, computer programs such as the "Woofer Tester" software was used to provide driver and system measurements (which include Qes, Qms, and Qtc) with different configurations of a variety of damping materials. We also worked with the original polyester damping material AR used with the same woofers in the later 70's.

Interestingly, the Qtc of the earlier models, with cloth surround woofers and rockwool stuffing, typically measures between .6 and .7. Later versions, with foam surround woofers and fiberglass stuffing, measure between .8 and 1. Whatever the case may be, my recommendation was meant to be general guidance for a person who had stated a preference for not handling old fiberglass. It was not based on conjecture or theory, but on testing and practical experience.

...and if AR's original tuning is a matter of concern, replacement foam surrounds on 35 year old woofers would have to be placed high on the list of variables.

Roy

[Analogman]

...which is why I mentioned differences between amounts and types of material, as well as placement within the cabinet.

A number of us have shared many notes on cabinet damping material behavior as it relates to the AR-5/3a era ARs. Along with listening tests, computer programs such as the "Woofer Tester" software was used to provide driver and system measurements (which include Qes, Qms, and Qtc) with different configurations of a variety of damping materials. We also worked with the original polyester damping material AR used with the same woofers in the later 70's.

Interestingly, the Qtc of the earlier models, with cloth surround woofers and rockwool stuffing, typically measures between .6 and .7. Later versions, with foam surround woofers and fiberglass stuffing, measure between .8 and 1. Whatever the case may be, my recommendation was meant to be general guidance for a person who had stated a preference for not handling old fiberglass. It was not based on conjecture or theory, but on testing and practical experience.

...and if AR's original tuning is a matter of concern, replacement foam surrounds on 35 year old woofers would have to be placed high on the list of variables.

Roy

I did an extremely thorough Aetna-Pollack detail job Thursday after confirming all the drivers could still carry the mail. Superlative results. These speakers kick ass. I may let a pair of JBL L96s go to make room for these; hard call, pressing these into daily service; I don't like revisiting jobs to service "break downs". As for Musicality, the ARs beat the JBLs hands down, and the L96 sure ain't no slouch. The ARs also yield more subtle information. An example of this is that conversations captured off mic at the Blackhawk are now intelligible, with the JBLs you just know they're there.

Listened to Miles Davis all day today on these "5"s, FANTASTIC! (even with the incorrect polyfil )

Thank you, Roy,

Craig

[Analogman]

Sorry for the double post.

Craig

[trask]

Congratulations on your 5's! I've got a refurb'd pair, and continue to learn just how good these sound; the tweeters have a "golden" sound. I had a new set of AR stands made for them -- getting them up off the ground makes a real difference. I've been trying them with first a couple of solid-state amps -- a Sony VFET, an original AR amp, and a Hegeman pre/Quad power combo. Of these I prefer the AR amp, as it just seems to have a way of making the speakers jump.

But a few days ago, I hooked up my Sonic Frontiers SFC-1 integrated tube amp (Push-Pull EL-34's), and the sound really came alive. Much fuller, voices and instruments much more "there". These are 8 ohm speakers of course, so not quite the current hogs as AR-3's, which may explain why I'm able to get away with only 50 watts tube power.

Next up, from from Terry DeWick some time this summer, will be a McIntosh MA-5100. It better be good, as leaving the tubes behind will be tough!

Keep on listenin'!

[Analogman]

It's amazing how they are improving the more I play them; as dramatic as "breaking in" new speakers,

and not just the new surrounds. These where virgins; the grilles had never been off since '72.

On the first run I had some transient vibrations/wheezing at the terminal cup on one box.

After the pot re-furbish I caulked the pots where they mount with some GM automotive gasket material (removable) and snugged everything up.

Beautiful!

Playing some "Prince" for a deep, artificial bass workout.

No more thoughts about subs.

Regards,

Craig

[Guest hlbarker]

Hi,

My first post here and of course, it's a question.

I am in the middle of a refurb on a pair of "5"s and need to know if the quantity of box stuffing was 32oz. as it was with the "2ax".

Your help is much appreciated.

Kind regards,

Craig

Craig,

I am also working on a pair of 5's and wonder if you replaced the caps and the pots as well? If so can you share what you replaced? Thanks, Jim

[RoyC]

After the pot re-furbish I caulked the pots where they mount with some GM automotive gasket material (removable) and snugged everything up.

Beautiful!

Playing some "Prince" for a deep, artificial bass workout.

No more thoughts about subs.

Regards,

Craig

Hello again Craig,

I agree with your enthusiasm for the AR-5.

As a veteran of the AR restoration wars, the AR-5 has emerged as my favorite AR speaker of that era. Even though the 3a has charismatic bass response and a pretty cabinet, I prefer the 5's versatility and overall balance at all but the very highest volume levels...which I personally rarely explore these days.

IMO, the 5 is worthy of the respect and careful restoration decisions usually reserved for the more popular, "higher end" AR models.

Roy

[Analogman]

Craig,

I am also working on a pair of 5's and wonder if you replaced the caps and the pots as well? If so can you share what you replaced? Thanks, Jim

NOOOOOO! DEAD STOCK, except for my woofer repairs, Aetna-Pollak rejuvenation

(very time consuming to do right in my opinion,

NO aggressive abrasives used, came out as new) and cosmetic/sealing work.

I learned THE HARD WAY not to jump in with both feet, until you have a reference.

The first major restoration I did years ago was a pair of AR-2ax(s).

I did them because of the fantastic memories of longing, and lust, they rekindled from my youth.

My eldest brother brought a pair home for my parents during Vietnam, along with a massive Sansui.......

the full page "black & white" ad copy in "Playboy" ........and on and on.................

Well, I fu&ked up, read too much from people that were very convincing, and bought into the whole "Layne" replace it all thing as well.

The result?:

An absolutely FANTASTIC, GORGEOUS pair of "2"s that AIN'T "2"s any more if you get my meaning.

They sound DAMN good, but I wound up with a LOT of money in them, more than any pair of these will ever bring......

But that's OK, 'cause I didn't do it for money in the first place and they taught me a Hell of a lot.

So I gave them to my 16 years old Daughter and they play loud bull shit night and day and she really digs 'em.

SO, SUCCESS!

My point is: I can't remember anything about how ARs sounded 30 plus years ago except "good".

The closest thing other than a new pair from a warehouse find is a lovingly stroked all original pair.

I plan on living with these for a while, as is, because just like tape noise or vinyl, I've never had problems with "old" or diamonds in the rough.

After I've identified anything I know I don't like that could possibly be old age related, maybe I'll be able to sweet talk

someone like Roy C. into helping with some suggestions, expertise and wisdom.

(I've F'd up a few amps diving in head first as well, never did know what they actually sounded like).

In the meantime I'm going to keep running these boys in, put my grilles and FABULOUS (if I may say so myself) polished badges back on tomorrow

and just keep diggin'

my AR-5s

I thank God for "craigslist" everyday.

Craig

[RoyC]

Craig,

I am also working on a pair of 5's and wonder if you replaced the caps and the pots as well? If so can you share what you replaced? Thanks, Jim

Jim and Craig,

It is nice to see the 5 getting some well deserved attention.

It is likely the old capacitors are out of spec and should be replaced. I recommend replacing all three caps (4uf, 24uf and 72uf) with film (polypropylene or mylar) caps. If the pots are beyond cleaning, ordinary 8 ohm l-pads can be used with a parallel resistor to make them act like the original pots. Some of us occasionally have spare pots, if needed. Check out the pinned "Restoring The AR-3a" document for some helpful tips. The 5 is very similar to the 3a.

Attached are a couple of pics of a recent AR-5 project, and an AR-5 crossover schematic.

Roy

AR-5 schematic (from AR).pdf

[Guest hlbarker]

Thank you Craig and Roy... I have refoamed the woofer and looked around the crossover a bit and it looks brand new. I will test the caps now that I have the values from Roys post and attached pics. After I refoamed one I connected it and it sounded ok but a bit muddy to me. It might be because I didnt reseal the woofer yet? Or would the leaky old caps be failing and sending too much to each driver? I used linseed oil putty on previous AR2ax rebuilds which sound fantastic after the cap replacement. I also on the 2ax's removed the pots and cleaned them in an electrlytic bath with baking soda and my battery charger. I agree with Craig's view that it is best to do no harm and I too only remember what the AR's sounded like back in the day with clear but fading memory. But to me the ARs (and the Dynaco A25) are the best sounding speakers ever made and I am gladly finding and restoring all I come across for future listeners to someday appreciate. Again, thanks for the replies, and if the pots cant be revived by cleaning I will need some other ones from salvage or some recomendations for L-pad replacements. Jim

[Analogman]

Jim and Craig,

It is nice to see the 5 getting some well deserved attention.

It is likely the old capacitors are out of spec and should be replaced. I recommend replacing all three caps (4uf, 24uf and 72uf) with film (polypropylene or mylar) caps. For a variety of reasons, I no longer recommend ordinary electrolytic caps. If the pots are beyond cleaning, ordinary 8 ohm l-pads can be used with a parallel resistor to make them act like the original pots. Some of us occasionally have spare pots, if needed. Check out the pinned "Restoring The AR-3a" document for some helpful tips. The 5 is very similar to the 3a.

Attached are a couple of pics of a recent AR-5 project, and an AR-5 crossover schematic.

Roy

No insertion of resistors required, just a straight swap? I've read elsewhere here that the "modern" caps don't "sound" right. If it's just a "one for one", I'd like to try that most definitely.

Are those Solens in the photos? Exact values? I used exact value Solens when I did the "2"s, but as I've already explained can't speak to the improvement.

Thank you again, Roy.

Craig

[RoyC]

No insertion of resistors required, just a straight swap? I've read elsewhere here that the "modern" caps don't "sound" right. If it's just a "one for one", I'd like to try that most definitely.

Are those Solens in the photos? Exact values? I used exact value Solens when I did the "2"s, but as I've already explained can't speak to the improvement.

Thank you again, Roy.

Craig

Check out the current LST vs AR-3a thread for a discussion on the small resistors. I have concluded that the sonic differences between original caps and new are predominately associated with deterioration issues of the old caps. The pair I mentioned above sounded quite good to me, yet I found that the 24uf and 72uf caps measured around 30uf and 80uf respectively...high, which is typical of aging caps.

The replacement caps are Dayton polypropylene caps (sold by Parts Express), which I happened to have on hand. They were within 5% of the original values at 4uf, 25uf, and 75uf...and sound fine. Solens would easily work as well. If you must stray from the original values, I recommend going slightly higher than lower, as it is a closer match to the typically higher values that most folks are sonically accustomed to.

Madisound seems to be stocking an ever increasing, and interesting, assortment of film caps. I strongly doubt you could go wrong with any of them.

Roy

[Analogman]

Check out the current LST vs AR-3a thread for a discussion on the small resistors. I have concluded that the sonic differences between original caps and new are predominately associated with deterioration issues of the old caps. The pair I mentioned above sounded quite good to me, yet I found that the 24uf and 72uf caps measured around 30uf and 80uf respectively...high, which is typical of aging caps.

The replacement caps are Dayton polypropylene caps (sold by Parts Express), which I happened to have on hand. They were within 5% of the original values at 4uf, 25uf, and 75uf...and sound fine. Solens would easily work as well. If you must stray from the original values, I recommend going slightly higher than lower, as it is a closer match to the typically higher values that most folks are sonically accustomed to.

Madisound seems to be stocking an ever increasing, and interesting, assortment of film caps. I strongly doubt you could go wrong with any of them.

Roy

Hi Roy,

Have you been pleased with the Daytons? I've never used them. Parts Express is the only place so far that has all the values (close) in stock, and they are in the Dayton brand.

This would make ordering so much simpler and not a "project". I've been interested in all the hype surrounding the new flavor of the month, "Auricaps" but no one vendor seems to stock all the #s. Does the "Law of Diminishing Returns" apply here? If so, I would be more than happy to try the Daytons.

What specific values did you use?

Sincere regards,

Craig

[RoyC]

Hi Roy,

Have you been pleased with the Daytons? I've never used them. Parts Express is the only place so far that has all the values (close) in stock, and they are in the Dayton brand.

This would make ordering so much simpler and not a "project". I've been interested in all the hype surrounding the new flavor of the month, "Auricaps" but no one vendor seems to stock all the #s. Does the "Law of Diminishing Returns" apply here? If so, I would be more than happy to try the Daytons.

What specific values did you use?

Sincere regards,

Craig

Hi Craig,

I was pleased with the outcome. The Daytons are especially good for the larger value caps due to their lower cost. If you want to try a more expensive cap, the tweeter's 4uf tweeter cap would be the place to try it. As stated above, I used 4uf, 25uf, and 75uf caps. Be careful or this thread will attract the capacitor police .

Roy

[Analogman]

Hi Craig,

I was pleased with the outcome. The Daytons are especially good for the larger value caps due to their lower cost. If you want to try a more expensive cap, the tweeter's 4uf tweeter cap would be the place to try it. As stated above, I used 4uf, 25uf, and 75uf caps. Be careful or this thread will attract the capacitor police .

Roy

It took a lot of time wasting, frustration, money and buyer's remorse for me to finally learn: in audio, high price does NOT guarantee high performance. Period and with no exception.

We'll go with the Daytons. Thanks for the values.

Now how's that for "The Emperor Has No Clothes"?!

Kind regards,

Craig

[Carlspeak]

It took a lot of time wasting, frustration, money and buyer's remorse for me to finally learn: in audio, high price does NOT guarantee high performance. Period and with no exception.

We'll go with the Daytons. Thanks for the values.

Now how's that for "The Emperor Has No Clothes"?!

Kind regards,

Craig

I learned al long time ago that in audio (and other areas of discretionaly spending) the cost/benefit relationship can be represented by an exponential curve. As cost rises exponentially, the consumer's benefit from the cost obeys the law of rapidly diminishing returns.