Garage sale AR3's...Now What... Questions

[Guest Deafears]

New guy here. Picked up a pair of AR3's for the right price. Plugged them in after breaking my back getting them downstairs. They play, but I don't like the sound. All the sound seems to be coming from the woofers and I can't tell any difference when I play with the pots. Now I have to try and figure out how much $$ they're going to cost me to get them to an acceptable sound quality level (and hopefully stop before it gets ridiculous!)

Here's some facts as I know them at this point. Hopefully some of you can give me a little guidance on what I'm in for cost-wise and maybe answer a couple questions to get me started:

Speakers appear to be mid-60's vintage. Mids have 1965 dates.

Enclosures are in very nice shape, but mis-matched finishes.

Woofers both have foam rot. One has hair-line 1" tear in cone.

All speakers make a noise with ohm meter (X1) across driver coils.

(woofers make decent snap, but rest are barely audible with 1.5volt)

I pulled the woofers, removed the insulation and looked for trouble. All seems in reasonable condition inside, but somebody's been in both boxes. I checked the wiring against the crossover schematics on this site and all seems correct except that three of the four capacitors are hooked backwards from the schematic. That is the diagram shows wire from cap to Mid pot B, then from 1 to speaker, but wiring is from cap to 1 then B to speaker. Not sure this makes any difference. Also neither speaker has the additional coils and 6uf cap the schematic shows.

That's as far as I have gone. Somebody went nuts with a staple gun on the crossover board so I haven't removed it yet or opened the pots or disconnected any wires.

Hopefully what I've mentioned is enough to give some of you experienced AR guys an idea of what I'm in for to reasonably resotre these. I know I need to pull the boards, unsolder & check components, open the pots, etc., to get more definative, but what are costs and availability of pots, caps, speakers, etc.? Is any of that stuff still available or will I have to substitute as best I can with afermarket components?

Couple more questions:

Boh mids and both tweeters sound very weak, but pretty identical with the 1.5v battery across the coil test. Is that normal or should there be a rather loud snap? Again, I didn't unhook any caps or coils that may have been in the circuit. Woofers sound ok with that test and sounded reasonably good for having foam rot.

Also, all these speakers have is the 24 & 6uf caps in the sealed box and a choke for the woofer. No extra 6uf or extra coil for the mid range speaker as sshown in the schematic. Is that OK?

Sorry this got so long! I promise to be more net in the future!

[Guest hilltroll67]

>>

>Sorry this got so long! I promise to be more net in the

>future!

>

>

I know what you intended to type, but I like this better.

I'm not the AR3 expert you're looking for, just wanted to say that I don't like your speaker test; a simple dcr check would be safer, I'm guessing.

Assuming that the drivers are OK, you can renew surrounds, recap, and repair or replace the pots for well under $100 the pair. BTW the mismatched shades of the veneer is a common thing; the pair of AR5s I bought new from the factory are like that.

Bob

[Guest Deafears]

Bob, I agree with your assessment of my speaker test. I was just trying something quick and dirty before disconnecting the crossover circuits to measure stuff. I assume the DCR people refer to is DC Resistance?

After posting late last night I realized my profile was set up to only view current posts. I've changed that and now see a wealth of info in archived posts that answer some of the questions I asked. Looks like a great site with lots of informed members willing to help!

Arkie

[onplane]

Arkie, the missing cap and coil were actually changes implmented in 65 and 70.

Vast majority of the time the reason sound is so weak in the mid driver and tweeter is massive corrosion in the pots. The wiring mod shown below should provide a permanent fix.

http://www.classicspeakerpages.net/dc/user_files/2238.jpg

Alternatively, Roy has designed a very clever and very cost effective substitute for the old pots using 8 ohm L-pads:

http://www.classicspeakerpages.net/dc/dcbo...ic_page=3#12656

If you want to retain the ability to adjust frequency balance, Roy's solution is, IMHO, the best solution as well as the low cost solution. Modern pots are often open in the back and I just don't like the idea of an exposed heat source in a closed box. Roy's solution will give you more than enough adjustment as typically you run the pots pretty close to full on. Final advantage is you lose essentially nothing in terms of power handling.

Hope this helps ...

Regards,

Jerry

[Guest Deafears]

Thanks Jerry. I pulled the mid pot on one speaker today and as you point out, it was full of green corrosion. So bad the B terminal was completely open. I cleaned it all up and on the bench at least the pot is working 100% now. I suspect that may be my problem with both speakers as the mid drivers show about 2.5 ohms across the coils. I'll pull the other 3 and clean them up over the next few days.

Attached is a photo of my crossover (if I can figure out how to post it). I think it is all standard (before the mods), but note that the caps seem to be backwards as far as terminals on the pots go. Does polarity make a difference here?

Also I'll try to post a pic of a woofer tear I have. I hate to even suggest this on an enthusiast board like this, but can something like this be glued some way without sacrificing sound quality? I hate to re-cone if I can get by with an adhesive. I was thinking of something like that stuff to repair vinyl seats. Kind of elastic.

Again, thanks for the help. I have your alternatives in the back of my mind for plan B if the pots don't last long.

(see photos)

[onplane]

Arkie,

The pots are NOT wired correctly. They will work the way they are wired if and only if the wipers are set to the max increase position.

Now, while this is the recommended position for modern media, you still have the problem with corrosion in the wipers. Often times the wipers are so badly corroded, that there is little metal left.

Before you pull the pots, unsolder the brown wire and re-solder to the green wire on the mid pot.

Next unsolder the black wire on the wiper terminal on the tweeter pot and re-solder to the black wire on terminal #1.

This is exactly the same as setting the pots to their maximum position 40 years ago before the corrosion set in. Hook your amp up and see whether you can get decent sound out of the mid and tweeter.

As for that cut, with your fingers spread evenly over the cone gently press in and see whether air escapes through that cut. If so, this is bad and will prevent the acoustic suspension from working properly.

The real solution is to re-cone. However, as a temporary fix you could try rubber cement, but ... light coatings! That is, once you achieve a seal and prevent air from leaking, don't apply any more cement.

This is guaranteed to alter the woofer's performance, but only your ears can tell how objectionable the result is.

Hope this helps ...

Regards,

Jerry

[Guest Deafears]

OH MAN I'M GONNA LIKE THIS!!!

I couldn't wait so got the other pot cleaned up and put everything back together. Playing some big band music from the Spitfire Band and it sounds GREAT! Even with the hole in the surround! I can adjust the pots now and it made all the difference. Love the bass it puts out. Think what it will be like with new surrounds and the other speaker hooked up!

Sorry Jerry but I didn't get back to the pc till I finished putting the speaker back together. You are right, both pots had about half the width of the wiper arm eaten away in a spot or two. Also one cuts out at the extreme end position. I'll try your suggestions after I get the surrounds replaced.

I felt for air where the tear is while the speaker was playing. I could detect nothing there that didn't feel the same an inch or so away as the speaker was moving. I can see the outline of the tear on the rear of the cone, but it doesn't look like it's gone all the way thru.

Thanks for your help. I'm really encouraged now that the mid and tweet are working. I've got an HT system with Magnepan MMG's and a Klipsch SW12 that I like for movies, but something about the AR3's that make MUSIC sound more "musical" I guess. That big band stuff really sounds great and not near as harsh as I'm used to.

[johnieo]

Arkie:

Please do not play your woofers until you have them refoamed. Without the acoustic air cushion, the voice coil may contact the back plate and cause damage to the coil former, or break it loose from the cone! OK very quietly to see if it works, but anything more could cause harm.

I would NOT recommend removing the potentiometers from the circuit. That is inappropriate advice, as it will change the response of the system. If you do remove the tweeter pot, but wish to replicate its "max" setting, try replacing it with a 20-to-25 W, 16-Ohm non-inductive resistor. The beauty of these speakers is listening them as they were designed. Roy's solution works--note that it does not remove the potentiometer resistance. If the wipers are not totally destroyed, try cleaning them with Deoxit and they will likely last a long time.

Cheers,

[soundminded]

>Arkie:

>

>Please do not play your woofers until you have them refoamed.

>Without the acoustic air cushion, the voice coil may contact

>the back plate and cause damage to the coil former, or break

>it loose from the cone! OK very quietly to see if it works,

>but anything more could cause harm.

>

>I would NOT recommend removing the potentiometers from the

>circuit. That is inappropriate advice, as it will change the

>response of the system. If you do remove the tweeter pot, but

>wish to replicate its "max" setting, try replacing

>it with a 20-to-25 W, 16-Ohm non-inductive resistor. The

>beauty of these speakers is listening them as they were

>designed. Roy's solution works--note that it does not remove

>the potentiometer resistance. If the wipers are not totally

>destroyed, try cleaning them with Deoxit and they will likely

>last a long time.

>

>Cheers,

I second all of these recommendations. The speaker depends on being air tight to function properly. The restoring force on the cone is the difference in air pressure between the inside and outside of the enclosure. Bass response will not be adequate if the speaker has an air leak and as John said, the voice coil could easily bottom out and be deformed, an expensive repair.

I also agree about the potentiometers not being jumped out. Operating them at full output is not the way to achieve the best balanced sound and will make the speakers sound forward, bright, and bass shy. If I couldn't restore or replace the pots, I'd used fixed resistors which achieved the factory indicated flat settings and I'd make any further adjustements to FR with an equalizer. I did not find deoxit satisfactory. I think a small wire brush, sandpaper, or some other abrasive will help. I had to disassemble mine completely as the center conductors were also corroded. They aren't fixed until all contact points are nice and shiny. Lucky me, I still have freon. I'd replace all of the capacitors. There is controversy among some people about whether or not more expensive polypropylene caps are superior to the common NPCs which are much cheaper. I'm not going to get into it but for AR2s I restored and the AR2as I'm going to restor, I'm using the cheap NPCs which are comparable to the originals. If I went to polypro caps, I'd buy Parts Express' own brand which are among the cheapest.

Be careful with the stuffing. It's quantity and arrangement are critical to the internal mechanical damping and therefore resulting FR of the woofer.

[RoyC]

Arkie,

Can you provide a full photo of your woofers? If your speakers are mid-60's vintage, I suspect that the person who screwed up the crossover wiring also replaced the original woofers...which had cloth surrounds in those days, not foam. From what I can see of the woofer in the photo you provided, I'm wondering if they are even AR drivers.

Re: the pots, it is important to maintain the parallel resistance they provided between the #1 and #2 terminals.

As John pointed out, it would have been around 16 ohms at the full "increase" (maximum) setting.

If you need pot parts or more details on how to implement modern 8 ohm l-pads, feel free to contact me through the forum.

Roy

[Guest Deafears]

John,Soundminded,

Thanks for the comments. I had read on this forum about not playing with rotted surrounds and was playing relatively quietly with no big excursions. Both surrounds are still mostly intactfd with only small holes, but I'll try to resist the urge to play them.:-(

My intent is to leave the crossovers functional, if possible. The one I did works, but not perfectly throughout the entire range of the pots. I did have to remove the pots and clean with sandpaper, crocus cloth and an eraser. It appears the wire coil in the pots is aluminum or something, not copper. Is this OEM? They said Aetna-Something brand.

The last can of tuner contact cleaner I got seems to attack plastic and shattered the plastic that housed the contacts in 2 relays I was cleaning. I was afraid to use it on the pots, so they are dry for now. Is Deoxit good stuff?

SOUNDMINDED, the fiberglass stuffing in both speakers came out in pieces and chunks and got stuffed in a bag. There was a piece of paper-type material that I thought might go over the hole in the woofer where the terminals are to prevent fiberglass getting between the cone and speaker frame. Other than that I might have to rent a Dwarf to crawl around inside there and lay up the packing according to the original placement.

Please let me know if there is some special packing I need to consider and how to do it.

[Guest Deafears]

Roy,

I think they are AR woofers, but you guys are the experts...

http://www.classicspeakerpages.net/dc/user_files/2244.jpg

http://www.classicspeakerpages.net/dc/user_files/2245.jpg

http://www.classicspeakerpages.net/dc/user_files/2246.jpg

http://www.classicspeakerpages.net/dc/user_files/2249.jpg

[soundminded]

Arkie; we've had this discussion many time before so you can see it in the archives. The fiberglass stuffing plays the same role in the speaker suspension as the shock absorber in the suspension of a car. It works by creating just the right amount of frictional drag when air is pulled or pushed between the fibers while the amount of trapped air works like the springs. Together with the mass of the cone, they act like a carefully tuned suspension which neither underdamps nor over damps the speaker but is critically damped to a very low freqeuncy, around 42 hz for AR3 I think. Try to use all of the fiberglass and put it back as close to the way it was when you found it, as uniformly as possible. If you have put it all together from both speakers in one bag, try to divide it exactly in two. I wouldn't get too overly concerned about it. It is better to use the orginal fiberglass than to try to find a substitute beause it will be difficult or impossible to duplicate the damping properties of that particular fiberglass for the same volume of air it displaces unless you can find someone who is expert in it. I think the original specification was 1.75 pounds per enclosure, perhaps someone else here can help out.

[RoyC]

The woofer basket and magnet are definitely AR, and fit the era, but they look like they were re-coned with a MUCH larger dust cap, and foam surround. Interesting....

You can smear a very light coating of Goop or fabric glue over the tear in the cone, if it is leaking. Do it on the reverse side of the cone, don't glop it on:-), and you will have a neat repair. It works very well.

Thanks for the photos!

Roy

[Guest Deafears]

Soundminded,

Thanks. I've only been on this forum a few days and there's alot to digest. I'll do some forum searches and try to replace as best I can. Fortunately I did pack the insulation in seperate bags. I thought about leaving the upper stuff in the enclosure, but too much dust and I knew I'd be in there fumbling with wires and speakers and having to look around for problems, so out it came.

[dynaco_dan]

Hi Roy;

Yes, it appears that the cone and dust cover are non-AR.

The AR alnico frame and magnet always appear built like a tank, great stuff.

Nice to also see the plastic screen covers for the frame openings.

[tysontom]

Arkie,

There have been several great replies to your question here, and all should be helpful to you. The problem I see with your AR woofer (it is an AR-1/AR-3 12-inch Alnico woofer, part number 3700) is that someone decided to replace the original cone and most likely the voice coil as well. I am immediately suspect that the cone might be much lighter than the original, or that the voice coil does not have the same overhang in the gap (the excursion capability). In general, if the cone is too light, the woofer would never meet the original specs and would thus also have abnormally high sensitivity and an elevated bass resonance frequency -- not good. Too little overhang in the gap and the woofer will have excessive harmonic distortion, also no good, since the AR-3 woofer was one of the very best woofers ever made when it comes to low distortion.

Over the years there have been few successful attempts at re-coning the original AR 12-inch Alnico woofer. I don't believe that there are any after-market OEM voice-coils and cones that even make an approximate match for that woofer, let alone replicate it. I noticed that the installer had also placed a masonite ring inside the outer flange to accomodate a smaller cone and surround, further indicating to me that this is a match made in hell.

Therefore, in the end, you would be *much* better off getting another exact, unmolested woofer for that great speaker.

--Tom Tyson

[Guest Deafears]

>Arkie,

>

>There have been several great replies to your question here,

>and all should be helpful to you. The problem I see with your

>AR woofer (it is an AR-1/AR-3 12-inch Alnico woofer, part

>number 3700) is that someone decided to replace the original

>cone and most likely the voice coil as well. I am immediately

>suspect that the cone might be much lighter than the original,

>or that the voice coil does not have the same overhang in the

>gap (the excursion capability). In general, if the cone is

>too light, the woofer would never meet the original specs and

>would thus also have abnormally high sensitivity and an

>elevated bass resonance frequency -- not good. Too little

>overhang in the gap and the woofer will have excessive

>harmonic distortion, also no good, since the AR-3 woofer was

>one of the very best woofers ever made when it comes to low

>distortion.

>

>Over the years there have been few successful attempts at

>re-coning the original AR 12-inch Alnico woofer. I don't

>believe that there are any after-market OEM voice-coils and

>cones that even make an approximate match for that woofer, let

>alone replicate it. I noticed that the installer had also

>placed a masonite ring inside the outer flange to accomodate a

>smaller cone and surround, further indicating to me that this

>is a match made in hell.

>

>Therefore, in the end, you would be *much* better off getting

>another exact, unmolested woofer for that great speaker.

>

>--Tom Tyson

Sorry for the delay in responding, I've been unavailable for awhile. Below are some pictures of one woofer after I removed the foam surround. If Tom's comments above are correct, I need to make a decision on how to proceed from this point, so looking for some suggestions. Cost IS a consideration.

Summary of the speakers at this point:

Both mids and both tweeters sound and meter identical.

All 4 pots have been cleaned and function sufficiently, but not perfectly.

Grill cloth and frames are missing. Cabinets in excellent condition, but finish is mis-matched.

Woofers sound and function ok considering the rotted foam surrounds. One has a 1 inch hairline tear that doesn't appear to be completely thru the cone. I can't comment on how the speakers sound compared to original as I have not heard AR3/3a's.

No crossover mods/updates have been installed. One choke coil (143 turn)appears original, other has been replaced. CAP blocks look original.

I have VERY little cost in this project so far. My options as I see them:

1. Replace the surrounds for $20 and live with what I have, or sell.

2. Sell what I can on Ebay or locally for parts or as-is as a package.

3. Spend several hundred for new woofers, maybe new l-pads, etc., etc.

Third option is probably the least desireable. My thought at this point is to replace the surrounds and see how I feel, but I'm open to suggestions.

If the fiberboard ring is not AR3 standard, how do I find a proper sized foam surround to replace? Are they all standard widths and all I have to worry about is the diameter?

http://www.classicspeakerpages.net/dc/user_files/2279.jpg

http://www.classicspeakerpages.net/dc/user_files/2280.jpg

http://www.classicspeakerpages.net/dc/user_files/2281.jpg

http://www.classicspeakerpages.net/dc/user_files/2282.jpg

[johnieo]

Arkie:

re: last proposed course of action. First, Alnico-magnet, cloth-surround AR woofers are no longer made. They were used in the AR-1 and AR-3. The only available woofers would be the ceramic magnet, foam surround woofers used in the later AR-3a (early AR-3a used the AR-3 woofer). I have never listened to a new woofer in the AR-3, but would suggest that it would be best to replace them with original unadulterated versions.

Try E-bay. Often pairs of Alnico woofers are up for auction. Sometimes one finds a battered pair of cabinets on which one can bid and then have only the woofers shipped. Alternatively, purchase a battered pair, keep the woofers, and sell the drivers and x-o on E-bay. It is not as significiant an investment as you might expect--especially if you have the time to wait until see a good deal that is going unnoticed by the crowd. You might find two singles for less than a pair. Look also for a pair of grilles/frames.

Patience will get you a pair at an attractive price. The AR-3 is a very nice speaker and worth restoring to its original condition without any cutsie modifications.

[Guest Deafears]

John,

Your suggestion is the ideal, but I live in a rural area where chances of finding the proper speakers is about nill. I am skeptical about Ebay and wonder how many I'd have to buy before getting 2 that actually reproduced sound like the originals. Seems like age alone reduces that chance significantly. However...you make good points and one thing I do have is time, so maybe I'll just wait awhile and keep my eyes open. I haven't been on the hunt for AR parts and perhaps now that I am, there will be more available than I think. Thanks for the comments.

[dynaco_dan]

Hi there;

I've had a bit of experience, buying off ebay, that is.

I have received a single AR 12" woofer and lot's of 10" AR and Advent woofers.

The masonite Advent woofers can be bolted face to face with no problem.

At least 1/4" bolts, nuts and washers.

The AR and most other woofers, with the 1/2 roll surrounds, need a 1/2" space between their frames, or the surrounds touch.

5/16" bolts would be better for the 12".

A single Advent woofer can use a flat piece of heavy cardboard for face protection but the AR and other types need a 1/2" spacer from plywood (best) with nuts and bolts.

You must almost hold the hands of some of the sellers in advising them how to package hifi goods.

A single AR 12" woofer of any type or brand, wrapped just in bubblewrap will surely be destroyed.

Offer to pay a little extra for the plywood support and nuts and bolts.

I specify how I would like everything packaged prior to shipment.

Last year I took some photos of a bad shipping experience and posted those photos here.

It was not to embarass anyone but to show the kind of damage that, can and does happen, in transit.

On a smaller note, AR-2 dual cone drivers.

I have now bought over 2 dozen but only 6 have made it to me and are functional and not damaged.

This is with me specifying how to package them.

Can you imagine if I didn't.

I also have received some exceptional packaging of some goods as well, so all is not bad.

I received several woofers boxed individually, the first one arrived flopping around in the carton.

The second one arrived and I saw the frame sticking out of the side of the carton at about 20 feet away.

Tha seller had used a cardboard face protection (an excellent idea) and lashed them together with copper wire, voice coil wire.

That fastening method lasted about 3 micro-seconds, if that.

One carton had inverted Christmas paper wrapping the carton.

The paper was just about all peeled off and with it would have been the address information.

The woofers, amazingly, were not destroyed, thank goodness.

This is not to scare you off but to let you know that some sellers wrap like the item like it will just sit in their closet on a shelf.

A crushed surround or dome is of no concern to some people.

[Guest Deafears]

Good post Vern and it points out another reason I'm skeptical about buying 40 year old speakers on Ebay. And if they do survive the transport, how reliable mechanically and electrically will they be? Still...some have had success. Not sure how many BARGAIN priced speakers were successful though and I'm not in that category that can afford to spend whatever it takes. (IE buy 24 to get 6!)

[dynaco_dan]

Hi again;

A number of years ago a seller from a small mail out hifi paper shipped me two AR-12" woofers.

He bolted them face to face and basicly carved a carrier out of sterifoam the shape of the profile of the 2 woofers.

They arrived in good shape.

I will share with long standing members via email only, my short good and bad sellers list.

One last horror story, a pair of Large Advent woofers were place face to face in a 2 cubic foot box.

Aluminum wire, actually fractional horsepower motor copper coloured winding wire, was used to tie them together, nothing else in the carton.

The wires cut probably before they left the sellers home.

Zap straps will not even hold KLH tweeters face to face, never mind woofers.

Some sellers use a black firm foam, great stuff, as a filler.

One seller refused to buy a roll of bubblewrap to package after saying how much a roll costs.

There is no standard for packaging, I have seen from one extreme to the other.

Some people take pride in their work and consider it to be packed as if they were going to receive it.