A new AR-3a owner here

[davidro]

G'day all, my first post here. I haven't even done much of lurking around. I usually lurk around at Audio Karma.

I got my pair of AR-3a last night. I love them. I listen to classical music mainly and achieving reproduction of orchestral sound is my aim. The 3a do that real well. I was amazed how revealing they can be. The difference between my Audio Technica AT95e and Ortofon Supreme MC10 has never been so clear and huge.

Here are photos of the drivers:

You can see the protective plate of the mid-range on the top photo is a bit broken during transit - is this replaceable/repairable? Necessary at all?

The only issue sound wise I'm facing is that I have to be very careful with the level knobs in order to make the drivers to operate. I guess I'll need pot cleaning. Not too sure as to how to open the cabinet though. Yes I've consulted the legendary guide but I'm new to AR and DIY. Please bear with me!

Cheers!

PS - sorry I note I double-posted...please delete one post if that's ok...

[dynaco_dan]

G'day all, my first post here. I haven't even done much of lurking around. I usually lurk around at Audio Karma.

I got my pair of AR-3a last night. I love them. I listen to classical music mainly and achieving reproduction of orchestral sound is my aim. The 3a do that real well. I was amazed how revealing they can be.

You can see the protective plate of the mid-range on the top photo is a bit broken during transit - is this replaceable/repairable? Necessary at all?

The only issue sound wise I'm facing is that I have to be very careful with the level knobs in order to make the drivers to operate. I guess I'll need pot cleaning. Not too sure as to how to open the cabinet though. Yes I've consulted the legendary guide but I'm new to AR and DIY. Please bear with me!

Cheers!

Gday mate

I see the missing piece of the mids mounting flange, just barely.

If you have the piece or pieces that are broken off you can reglue them on with the driver removed from the cabinet.

If you have the piece or pieces you may when gluing drill at right angles to the cracks a small hole

and stick in a metal nail or similar with glue and this will give some additional support.

The acoustic seal of then enclosure is likely compromised by air leaking out at that point.

The level control pot dropout is a very common problem and if it occurs all the time then you have at minimum two choices.

A tedious job is to remove and clean the interior of the pots.

Another is to replace them with perhaps Ohmite pots.

There is other options which I will leave for someone else here.

If it isn't that much of a pain just listen and enjoy them until they stop working.

[davidro]

Gday mate

I see the missing piece of the mids mounting flange, just barely.

If you have the piece or pieces that are broken off you can reglue them on with the driver removed from the cabinet.

If you have the piece or pieces you may when gluing drill at right angles to the cracks a small hole

and stick in a metal nail or similar with glue and this will give some additional support.

The acoustic seal of then enclosure is likely compromised by air leaking out at that point.

Thanks mate - does that mean I'd better leave it as it is because the seal may be compromised if I tried to fix it?

The level control pot dropout is a very common problem and if it occurs all the time then you have at minimum two choices.

A tedious job is to remove and clean the interior of the pots.

Another is to replace them with perhaps Ohmite pots.

There is other options which I will leave for someone else here.

If it isn't that much of a pain just listen and enjoy them until they stop working.

I think I will eventually have to clean them. I wasn't sure where to find the info re opening the cabinet in the Guide though.

Thanks for your help mate, cheers.

[dynaco_dan]

Thanks mate - does that mean I'd better leave it as it is because the seal may be compromised if I tried to fix it?

I think I will eventually have to clean them. I wasn't sure where to find the info re opening the cabinet in the Guide though.

Thanks for your help mate, cheers.

Hi again

You will need to determine when the woofer is pumping, if any air is leaking out of that hole before doing anything else.

[davidro]

Ok mate I'll see if the woofer pumps when I play music tonight. Thanks. Cheers.

[davidro]

I've just checked it out - the woofer is not pumping at all. What from here? Cheers.

[JKent]

I've just checked it out - the woofer is not pumping at all. What from here? Cheers.

Hi David and welcome!

There are a couple of things to bear in mind: The AR is an "acoustic suspension" speaker system that depends on a totally sealed cabinet to work. You are probably experiencing a leak where that flange is missing. The other common leak is the cloth woofer surround but you have foam surrounds so that would not be the culprit (unless the foams have deteriorated, in which case you are looking at a "re-foam" job).

Here is a test: With no music playing, push in on the woofer that is in the cabinet with the broken mid flange. It probably comes right back out. Now try the other woofer. It should take 1 to 1.5 seconds to return. That's how it should be. If the woofer returns immediately, there is an air leak.

The way drivers are sealed to the cabinets is with a material similar to window putty. Some people use "Mortite" putty. A very good alternative is "duct seal." It is sold in electric supply houses or home centers in the electric dept. Comes in a brick of about 1 pound and is more than you will ever need. Or, Parts Express sells some very handy "speaker gasketing tape" http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-542

Are you in Oz or just talk that way? Don't know what is available down under.

To get inside the cabinets you have to remove the woofers and the fiberglass stuffing. I'm sure this is covered in the restoration manual. Then you can remove the pots and clean them, or replace with reliable, inexpensive L-pads. But before going to that work you could try just rotating the pot controls back & forth many times to try toscrape the contacts clean, then try to find a good spot and leave them there. There will probably be "dead" spots, so fiddle with them until they are good.

Stay in touch and we'll try to help

Kent

[dynaco_dan]

I've just checked it out - the woofer is not pumping at all. What from here? Cheers.

Hi again

If the opening is, and it is very likely, completely open to the cabinet I would suggest one of two ways to test it.

Hold a lit cigarette in front of the opening a few inches away with music containing some bass.

Another is a candle.

Make certain you do not go closer than an inch or so.

The smoke or flame should move back and forth if the leak is large.

Kent has suggested pressing on the center cone area and watch the time of it's return to normal position.

Please do not start smoking just to do the test. LOL

Have you saved the broken pieces?

There is usually a substantial amount of putty under the flange and this may keep the integrity of acoustic seal of the cabinet.

Actually I went back and I think I see a white gasket in the opening.

If you have no leakage and you do not need to dig into the cabinet, may I suggest just applying some putty to that opening.

It is not what a service tech would do but why disturb anything if you do not need to at this time.

The remaining screws will still hold the driver in place.

If you have a leak you may need to do a plastic faceplate repair.

This would mean removing the driver, its very heavy and tough removing straight out.

The weight and magnet size means a gentle pulling is required equal distant.

[davidro]

Hi David and welcome!

There are a couple of things to bear in mind: The AR is an "acoustic suspension" speaker system that depends on a totally sealed cabinet to work. You are probably experiencing a leak where that flange is missing. The other common leak is the cloth woofer surround but you have foam surrounds so that would not be the culprit (unless the foams have deteriorated, in which case you are looking at a "re-foam" job).

So that means I only need to seal them right? No need to say vacuum or anything?

Here is a test: With no music playing, push in on the woofer that is in the cabinet with the broken mid flange. It probably comes right back out. Now try the other woofer. It should take 1 to 1.5 seconds to return. That's how it should be. If the woofer returns immediately, there is an air leak.

You mean the dust cap in the middle? Can I push it in? I just want to make sure before I do something stupid lol

The way drivers are sealed to the cabinets is with a material similar to window putty. Some people use "Mortite" putty. A very good alternative is "duct seal." It is sold in electric supply houses or home centers in the electric dept. Comes in a brick of about 1 pound and is more than you will ever need. Or, Parts Express sells some very handy "speaker gasketing tape" http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-542

Are you in Oz or just talk that way? Don't know what is available down under.

Yes I am. How about this? http://www.jaycar.com.au/productView.asp?ID=NM2840&keywords=speaker+seal&form=KEYWORD Looks pretty similar? I can just use this tapes to seal the broken area?

To get inside the cabinets you have to remove the woofers and the fiberglass stuffing. I'm sure this is covered in the restoration manual.

I wasn't sure if that's how you do it - thanks!

Then you can remove the pots and clean them, or replace with reliable, inexpensive L-pads.

Is that covered in the Guide? I'll have a look. Thanks. But I'd like to retain the originality as much as possible - I love these speakers!

But before going to that work you could try just rotating the pot controls back & forth many times to try toscrape the contacts clean, then try to find a good spot and leave them there. There will probably be "dead" spots, so fiddle with them until they are good.

Will do - thanks heaps mate!

Stay in touch and we'll try to help

Kent

Thanks Kent for your help. Cheers.

[davidro]

Hi again

Good morning!

If the opening is, and it is very likely, completely open to the cabinet I would suggest one of two ways to test it.

Hold a lit cigarette in front of the opening a few inches away with music containing some bass.

Another is a candle.

Make certain you do not go closer than an inch or so.

The smoke or flame should move back and forth if the leak is large.

Done that just now with a candle (so as not to start smoking lol) - no movement with the flame.

Have you saved the broken pieces?

I have but I doubt they're all there....some missing maybe.

There is usually a substantial amount of putty under the flange and this may keep the integrity of acoustic seal of the cabinet.

Actually I went back and I think I see a white gasket in the opening.

If you have no leakage and you do not need to dig into the cabinet, may I suggest just applying some putty to that opening.

It is not what a service tech would do but why disturb anything if you do not need to at this time.

The remaining screws will still hold the driver in place.

Gotcha

If you have a leak you may need to do a plastic faceplate repair.

This would mean removing the driver, its very heavy and tough removing straight out.

The weight and magnet size means a gentle pulling is required equal distant.

Can you please further explain 'a plastic faceplate repair'? Why do I need to open the cabinet? Can't I just seal the broken area with that putty or sealant tapes?

Thanks for your ongoign help

Cheers

David

[JKent]

No vacuum—just sealed.

Don't push in the dustcaps. Place your fingers on the cone, around the edges of the dust cap.

That stuff should work. Usually we use soft stuff similar to window putty or children's plasticene modeling clay, but it says it is for two 12" woofers.

Pot restoration is covered in the Guide. Also various places in this forum and elsewhere. You can clean them and they will be fine for a while. Some of us like the L-pads because they last. Roy tells how to attach a resistor to simulate the original pots (in the Guide), but you can certainly clean and use the originals if they are not too far gone. I have found that about 50% of them are beyond repair.

Regarding your mid's faceplate; is it plastic? I thought they were all metal.

Good luck!

Kent

[davidro]

G'day mate - I just pushed the cone. Both woofers come out at about the same speed. not 1.5 sec though, but it's sort of slow. The faceplate is plastic, that why it broke I think. The tweeter faceplate also is a bit cracked I see.

[JKent]

OK. Let's stop and take a breath. You said the speakers sound great. Maybe you should just stop there and enjoy them.

I'm afraid we got off on a tangent when you said the woofers were not "pumping." Maybe the music you listen to and the volume levels you prefer don't cause much visible woofer excursion.

If your candle test showed no air leak, and pushing the woofers causes them to return "sort of slow" all is probably OK.

I am not familiar with plastic faceplates on the 3a but if there are no leaks I'd suggest leaving them alone. You have front-wired tweeters and mids. The leads on those are literally as thin as hairs. If you try to remove the drivers you WILL break the leads, and that's a PITA.

Removing the woofer is not a problem, except that sometimes the putty is very hard and it's tough to pry them out. Then you have to be careful of the Kimpac sheet that keeps fiberglass out of the woofer, but that's no big deal. So if you want, go ahead and clean the pots. But consider leaving well enough alone as far as the mids and tweets.

Kent

[dynaco_dan]

Good morning!

Can you please further explain 'a plastic faceplate repair'? Why do I need to open the cabinet? Can't I just seal the broken area with that putty or sealant tapes?

Thanks for your ongoign help

Cheers

David

Hi again

The faceplate on the midrange drivers were black plastic, maybe ABS, I don't know for certain.

The front magnet faceplate had bolts cast into the black plastic.

I saw an AR-5, same driver size, once, with a report of no midrange range sound output, I removed the grille cloth and everything looked really fine as always.

I connected the speaker to an amplifier and there was no midrange output.

I looked at the front baffleboard again and with closer inspection the screen and flange was still in place, just no dome inside.

The magnet is so heavy the speaker may have been dropped on it's back and separated.

That is quite a feat to do.

If you had too large of a hole so that air was leaking through it then you would need to remove the mid.

You couldn't do a proper job of reattaching the pieces unless it was out of the recess.

You did the leak test and if that is all she wrote I would leave well enough alone and just enjoy.

As always the magnets on these drivers is very strong and can demagnetize credit cards real easy.

[davidro]

G'day guys thanks for your advices. I wonder if I put the broken pieces (what's left of them that is) into the place and seal them over with say blu-tack (same as putty?) as a cautionary measure. What do you think? Plausible? Cheers.

[kirk57]

G'day guys thanks for your advices. I wonder if I put the broken pieces (what's left of them that is) into the place and seal them over with say blu-tack (same as putty?) as a cautionary measure. What do you think? Plausible? Cheers.

Yep, that's what I would do. Blu-tack (or Mortite) would seal any leak due to the broken tweeter.

[dynaco_dan]

G'day guys thanks for your advices. I wonder if I put the broken pieces (what's left of them that is) into the place and seal them over with say blu-tack (same as putty?) as a cautionary measure. What do you think? Plausible? Cheers.

Hi again

I would put the pieces in a small Ziploc type bag and staple it just clear of the front of the driver so it will not get lost.

Usually I would have written, "tape it to the rear of the cabinet," but it could get lost.

You can still place some dark putty in the hole for cosmetic reasons or not.

[JKent]

G'day guys thanks for your advices. I wonder if I put the broken pieces (what's left of them that is) into the place and seal them over with say blu-tack (same as putty?) as a cautionary measure. What do you think? Plausible? Cheers.

I "thought" you had downloaded and read the Guide. In case you have not, here is the link:

http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

Even if tackling the pots is not in the immediate future, the Guide makes for interesting and informative reading. Enjoy those speakers!

Kent

[davidro]

Yep, that's what I would do. Blu-tack (or Mortite) would seal any leak due to the broken tweeter.

Blu-tack a lot easier to be had here so I might just do that - thanks.

Hi again

I would put the pieces in a small Ziploc type bag and staple it just clear of the front of the driver so it will not get lost.

Usually I would have written, "tape it to the rear of the cabinet," but it could get lost.

You can still place some dark putty in the hole for cosmetic reasons or not.

So apart from cosmetic reasons you don't see much value in it?

I "thought" you had downloaded and read the Guide. In case you have not, here is the link:

http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

Even if tackling the pots is not in the immediate future, the Guide makes for interesting and informative reading. Enjoy those speakers!

Kent

I have it in a hard copy now. I've only read it briefly looking for the bits that I wanted to know on the screen. I might sit down and have a long look. Cheers.

[davidro]

Ok guys I've read the Guide. Some questions though:

1. It is indicated replacing L-pad with the pots might affect the sound - so that's not a good idea?
   
2. Is it necessary to open the mid range and tweeter just to replace the pots?
   
3. Can I re-use the stuffing?
   
4. Caps - exactly what caps should I use? Any definite examples?
   

I have a Hioki 3280-10 'Clamp on HiTester' without the lead that looks like this - is it sufficient for Vol-Ohm meter?

Thanks for the helps

Cheers

[davidro]

Hope I'm not boring people too much here.

Took photos of mid ranges and tweeters. I think they definitely look different. It looks as though the mid-range with broken panel has some sort of glue stuff on it. The screws look to be different too. From the Guide it looks as though the ones without broken panels appear to be A.13 while the ones with broken panels appear to be A.12. Not a matching pair perhaps?

I would really like to fix the broken panel. Any suggestion?

Plus, while the candle test didn't reveal air leaks, my reading of the Guide makes me feel the woofers come out a little too quick when I push them in. Both of them. I might need to re-seal them tight.

I'm planning a full restoration - replacing caps and pots, bleach/replace the grilles & re-finish the cabinet.

Please help!

[JKent]

Hi David

1. Replacing the pots with L-Pads "may" affect the sound, but that's why Roy described adding a resistor, so they sound like pots. I use L-pads myself. They are reliable.
2. No--do not remove the mid & tweet. Work through the woofer hole
3. You can re-use the stuffing if it is fiberglass. Rock wool should not be re-used (see Guide). If needed, new fiberglass "should" be available in home centers. It's just building insulation.
4. Caps: Everyone has an opinion, some very strongly held. The caps must be non-polar. That means either non-polar electrolytics (NPEs also called bi-polar) or film caps (Poly, mylar). You could use both. Film caps are bigger and more expensive but don't wear out. NPEs are small and cheap and last 2, 3 or maybe 4 decades. I don't know what brands are sold in Oz. Solen capacitors are sold worldwide and are reasonably priced. Maybe you could check Aussie mail-order suppliers, get some specifics and post again. The AR3a has 3 caps: 6uF, 50uF and 150uF. Definitely use a film cap for the 6. You can use either film or NPE for the 50 and 150.

That meter is something electricians use. Don't think it is suitable for electronics, OTOH you really don't need a meter to replace pots and caps.

This place has Solen and Bennic film caps: http://www.speakerbi...chkey=capacitor This outfit has 47uF (close enough) and 150uF Non-polarised (Brit spelling) caps and 5.6uF “metallised / polypropylene” caps (also close enough) http://www.voltelect...tor+6uF&x=0&y=0 If you want, you can add this in parallel with the 5.6: http://www.voltelect...-capacitor.html These are just examples. I’m sure if you do a search you will be more likely to turn up Australian sellers. Try “speaker parts” or “speaker capacitors” or “non-polarised capacitors”, “film capacitors” etc. or search specific values such as “150uF capacitor”. You will come across places that sell very high priced caps: Mundorf, Hovland and the like. Totally unnecessary.

Many of us in the US order from http://www.madisound.com/ or http://www.parts-express.com Either of them may ship to Australia, but of course the shipping cost may be significant.

I'm hoping Roy will jump in regarding the mids and tweets. They do not match but they may be sonically equivalent and not a problem. As far as repair goes, it depends on what kind of plastic they are. I've had good success with a product called Plas-T-Pair but it only works on plastics that can be "welded" with acetone. You could try picking up some acetone at a hardware store and see if it melts the plastic (just use a tiny drop and see if it runs off like water or makes the plastic sticky). If the acetone works, you could use that to glue broken pieces back together. The advantage of Plas-T-Pair is it includes some powdered plastic so you make a paste to fill voids. It has to be tinted with a coloring agent available at auto body repair suppliers. If that won't work, you can use another automotive product: Q-bond, or use a very strong epoxy (JB Weld is what I use). Take a look at my KLH Model Eight Restoration Guide, attached to Post #1 here: http://www.classicsp...?showtopic=6387

On page 5 I describe using Plas-T-Pair and on pages 9-10 I describe using Q-Bond and JB Weld.

Those faceplates appear to have been broken by over-tightening. When they are reinstalled, be sure to use enough gooey caulk and then tighten snugly but not overly-tight. Tighten them the way you would a wheel on a car: The 12 o'clock position, then the 6, 9, 3, then 12 again etc. And remember to use the utmost care when removing them. Peel off the electrical tape gently to expose the very thin leads, then carefull unsolder the leads from the terminal strip on the front of the speaker baffle. Use a pencil type soldering iron (not a gun) and buy a plastic "solder sucker" like this: http://www.amazon.co...r/dp/B005GIPKOW

Kent

[dynaco_dan]

Hope I'm not boring people too much here.

Took photos of mid ranges and tweeters. I think they definitely look different. It looks as though the mid-range with broken panel has some sort of glue stuff on it. The screws look to be different too. From the Guide it looks as though the ones without broken panels appear to be A.13 while the ones with broken panels appear to be A.12. Not a matching pair perhaps?

I would really like to fix the broken panel. Any suggestion?

Plus, while the candle test didn't reveal air leaks, my reading of the Guide makes me feel the woofers come out a little too quick when I push them in. Both of them. I might need to re-seal them tight.

I'm planning a full restoration - replacing caps and pots, bleach/replace the grilles & re-finish the cabinet.

Please help!

Hi again

You have different tweeters and mids.

The damaged unit and it's mate tweeter are an earlier version.

Can you now post the serial numbers.

It appears that the broken mid also has a crack that I could not see earlier.

The likelyhood of it leaking air is now more to my way of thinking.

There is more of an opening than seen at first glance, even with the white sealant tape gasket I would recommend a repair.

The tape is not an appropriate stopgap.

My earlier suggestion of removing it and glueing the pieces with small nails or wire or ? crossdrilled for added strength.

This cannot be done without removing the driver, to do it properly.

The glue maybe for ABS plastic pipe or try epoxy.

[RoyC]

I'm hoping Roy will jump in regarding the mids and tweets. They do not match but they may be sonically equivalent and not a problem.

The unbroken midrange and tweeter (2nd photo) are later back-wired versions, which have been converted for front wiring. They are a sonic and electrical match to the front wired versions in the first photo.

Roy

[davidro]

G'day all, thanks for your help.

Hi David

Replacing the pots with L-Pads "may" affect the sound, but that's why Roy described adding a resistor, so they sound like pots. I use L-pads myself. They are reliable.

Ok, thanks. Are all L-pads of same size and specs? I couldn't find one on the Aussie parts shop (i.e. Jaycar). Another place sells each for like $35. It looks cheaper to import them from UK. eBay item no. 380345706372 appears to be one. What do you think? And do I need 4 of this?

I'll have to come back to the caps question. It's a bit confusing to me as I have no understanding of electrical parts.

Thanks for your help!

Cheers