New pair of AR-3a's, looking for advice on restore

[Guest SamS]

Hi all,

New here, but hang out frequently over at stevehoffman.tv, AA, AK, etc.

I just won this ebay auction: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...AMEWN%3AIT&rd=1

So, today I got my first pair of vintage ARs (even a deal lower than ebay price for local meeting). These go in my second system, powered by a Sony STR-GX10ES stereo receiver.

I've been reading this board for the past few days, and hope you all can help steer me in the right direction for getting these speakers to optimal condition.

Mechanically, they'e almost OK. Surrounds have been replaced (albeit somewhat sloppy), but driver, midrange and tweeter condition appear to be above average showing no abuse. The level controls are indeed scratchy. In fact, on one speaker, the tweeter cuts out at all but the max setting. Even then it sometimes sounds "spitty" and distorted. However, I have played 8000hz tones and verified that the potentially troublesome tweeter does work. It is not my opinion that this one tweeter has failed, but someone can correct me.

For me to get a decent sound, I have to crank both tweeter and mid controls to max point. From what I understand this should not be the case. I would like to explore replacing or cleaning the level control boards. Can someone point me in the right direction of steps? I have very limited soldering capabilities, but I am patient and would be eager to follow tips or suggestions.

I am also interested in any other cosmetic or mechanical restoration tips. I prefer to keep components to vintage specs, only upgraded if it is the standard practice for those restoring AR3as. Also, any tips on specific wood cleaners or finishers is appreciated. They look nice cosmetically, but a good wood treatment would be desirable.

Thanks for all suggestions!

-Sam

[JoeB]

Congratulations on your ‘new’ speakers. In my opinion, the AR-3a is a very good speaker. I recently purchased a pair of AR-3a's and had a similar problem with scratchy pots. I disassembled the two in the worst speaker and tried to clean them up. One cleaned up OK, the other was too badly corroded. According to the AR-3a crossover schematic and parts list (in the library section of The Classic Speaker Pages), the factory settings are 1.75 Ohms from the top (1 to for the tweeter and 3.25 Ohms from the top for the midrange. If the tweeter and midrange are 4 Ohms, then this is equivalent to -3.8 dB on the tweeter and -6.3 dB on the midrange (from full on). These are quite noticeable differences. I have seen suggestions that L-Pads have worked for some folks, but I personally would choose to keep the crossover electrically identical to the way AR designed it. I chose to wire up a switch with several power resistors to allow at least a gross adjustment. I have since designed a switched attenuator (12 positions) to allow fine adjustment of the driver levels without using a pot and maintaining the exact crossover electrical characteristics. I’ll be installing them in my ‘new’ AR3-a speakers, probably within a week or so. I believe this will be an optimal solution.

If your controls clean up – great. If they don’t, a quick and dirty solution is a 1.75 Ohm resistor in series with the tweeter (10 Watt should work) and a 3.25 Ohm (10 Watt) in series with the midrange (from 1 on the pot to the driver). This should get you close to the factory setting (or maybe just a tad brighter) for now. Warning: this may not be the sound you are looking for since the 3a’s are a fairly neutral speaker. I’d leave the 16 Ohm pots in place. The 1.75 Ohm would go in series with the BLACK lead to the tweeter, the 3.25 Ohm in series with the GREEN wire to the midrange. Heat shrink tubing is very handy for making a neat install.

About soldering:

WEAR SAFETY GLASSES WHEN SOLDERING ON THESE SPEAKERS. There are wires soldered with a lot of solder and, if you are pulling on one and it gives way quickly or springs sideways it can throw solder drops quite a ways. Better safe than sorry.

I found that removing the magnet wire from L1001#1 to pin ‘1’ on the midrange pot to be tricky. I ended up cutting it as close to the pot as I could. I scraped off the end quarter inch of the magnet wire with a sharp knife (that coating is tough) and soldered a piece of wire to it so I wouldn’t have to deal with it ever again. I soldered the added wire back to pin 1 of the pot after cleaning it.

I used a dust mask and disposable gloves to deal with the fiberglass stuffing. I opened the speakers outside, stored the fiberglass in a cardboard box, then replaced it afterwards. I could go on, but hopefully these few tips will help.

[Guest SamS]

Joe, thank you for your detailed explaination.

Would this Lpad be a sufficient replacement?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...AMEWA%3AIT&rd=1

What else would I need? Besides two (four?) of them?

[JoeB]

>Joe, thank you for your detailed explaination.

>

>Would this Lpad be a sufficient replacement?

>

>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...AMEWA%3AIT&rd=1

>

>

>What else would I need? Besides two (four?) of them?

Sam,

I’m probably the wrong person to ask about that because I’m kind of a believer in maintaining the original design. I couldn’t tell from the listing whether the L-Pad is 8, 16, or 4 Ohms. The driver is supposed to be 4 Ohms and it would therefore require a 4 Ohm L-Pad to “hold the crossover point constant independent of the control setting”. This is not what the original design did. The actual impedance seen by the crossover is 4.9 Ohms on the tweeter when set to factory setting (1.75 Ohms from top) and 6.3 Ohms on the tweeter when set to factory setting (3.25 Ohms from top). It is possible to build a spreadsheet for any particular value of L-Pad, but that might be overkill. In general I suspect a 16 Ohm L-Pad would be closest to the original. An 8 Ohm L-Pad would assume the driver is 8 Ohms and would be lower in impedance than the original AR pot at anything but the highest setting. A 4 Ohm L-Pad would be quite a bit lower in impedance than the original 16 Ohm pot at any setting besides full on and probably dissipate a lot of power.

Again, I’m a believer in keeping the electrical parameters of the original design unchanged. Maybe some folks who have put L-Pads in as replacements for the pots could comment.

[RoyC]

Sam,

Those are 8 ohm l-pads shown in your link, not (16 ohm) potentiometers like those currently installed in your AR-3a's. Much has been posted on this topic. The recent AR-2ax l-pad thread would be a good place to start.

The EIA numbers on the back of your speakers indicate that they were built in late 1974, near the end of the 3a era. I am willing to bet that the pots still have much life left in them, and just need to be dismantled and cleaned.

The "black" midranges in your cabinets are AR replacements from the later '70's through the '90's.

When you remove the woofers, look for dates stamped on the magnets. They appear to be from a later time as well.

Roy

[Guest SamS]

@Joe: I'm in the same camp as you, would rather keep original design. That is great info on the ohm rating differences.

Roy, Thanks for the tip on those Lpads. I *almost* pulled the trigger to buy them.

So you think someone's already done some driver replament at one point in their life...hmm.

And my next best step is just to take out the woofer, and tackle cleaning the switches? Please recommend cleaning procedures (digging through the 2AX Lpad thread now) and cleaing fluid/solutions for the potentiometers.

Will I need some moretite before I start? Anything else before I start ripping these suckers apart?

[JoeB]

Roy made a good point. If the pots are newer they may not be as oxidized. The place I had a problem with on the pot I couldn't save was the center connection. The metal was totally corroded. Once you take the pot apart (it's easy and obvious when you have it in front of you) you will see the condition immediately. I have heard deoxit recommended, and that might help. BTW, my suggestion for fixed resistors is only if the pots can't be saved. If you can save them, great.

I'm not sure putty is used on your speakers. I think later AR-3a's had gaskets.

Good luck.

Joe

[Guest SamS]

Good info Joe.

I need to get some more deoxit.. dang that stuff is expensive. Any recommendations for something cheaper to soak/scrub them in (assuming they're not toast) would be appreciated.

[Robert_S]

> So you think someone's already done some driver replacement at one point in their life...hmm

Just taking a wild guess, the woofers look like they may be from around '83/'84 (perhaps with square magnets).

That fact that they are not original should not diminish your listening pleasure. To quote Tom Tyson:

"Basically, all these flat-side woofers are interchangeable, and have almost identical characteristics with only minor differences. Power-handling is much greater on the later woofers, but the distortion, frequency response and so forth (when mounted identically) are all very close."

However, many passionate enthusiasts (and detail obsessives!) seek out drivers from the correct time period.

[RoyC]

Sam,

You will probably have to use some fine sandpaper to remove the oxidation. Some folks use a dremel tool.

Attached is an old photo of a disassembled AR pot that was partially cleaned. It should give you an idea of what you will be dealing with.

Roy

http://www.classicspeakerpages.net/dc/user_files/1419.jpg

[Guest SamS]

Excellent info guys! The pic helps a lot too.

Just realized I'll spend this weekend working on my girlfriends car (smashed front end yesterday) sigh... speakers will have to wait a few days

Luckily, fooling around with the controls has given me sound from both tweets/mids. Although the level controls are cranked, the speakers sound very nice and balanced. That midrange is spectacular. Male vocals really benefit from a bigger woofer and the mid/woofer x-over slope sounds very pleasing to me.

[Guest Electrospark]

Hey now,

I have 6 pairs of 2ax's a pair of 4's and a pair of 3's, and I finally GOT OVER cleaning those pots! I now officially hate everything about them. They go bad after a while (at least in florida), the part that touches the resistor wire wears thin, corrodes, the wire clip that holds the cap on, etc.

The best money I ever spent on the 3s was on new pots and caps. I bought the crossover kit from Layne Audio, for a resonable amount. It was more than the parts would have cost from Parts Express or somewhere, but it came with instructions and a schematic to "correct" the polarity if desired, I called Steve and we talked for a half hour, or rather he talked speakers and I listened.

Worth every penny.

Nice smooth adjustment with no dead spots!!!

[dynaco_dan]

Hi there;

When did you buy from Layne?

We've had comments that Layne was down and out last year or at least no responses for a long period of time.

Replies from Layne were harder to get, than seeing a dual woofer version of an AR-LST.

If they are back on track, please let us know.

What did you replace the pots with?

[Guest SamS]

Yes, I'm curious as to what you replaced the pots with as well.

I'm going to try and tackle the pots disassebmly next weekend. I would prefer to keep them as stock as possible, so modifying them doesn't appeal to me as much. However, if I can be more certain that replacement l-pads would keep the exact same characteristics of the original pots, I'd be more likely to modify.

Sam

[Guest SamS]

What would you guys think about soaking the pots in something like CLR brand metal cleaner? That stuff really works for taking corrosion off of sinks and the like.

Would it be preferable to go after them with the dremel tool?

[Guest Electrospark]

>Hi there;

>

>When did you buy from Layne?

>

>We've had comments that Layne was down and out last year or at

>least no responses for a long period of time.

>

>Replies from Layne were harder to get, than seeing a dual

>woofer version of an AR-LST.

>

>If they are back on track, please let us know.

>

>What did you replace the pots with?

I did the restoration in 2003. Sorry to hear he's not around or is involved in other things. When we talked back then, he seemed to be developing some small high-end speakers for the consumer market ($$$).

Anyways, the kit came with high voltage polypropylene caps; 24/25uf for the mid, 6uf for the tweeter (Solens? I forget.) the pots were high grade, real smooth, but I forget the ohms (14 ohms is the old one, right?), and the manufacturer was not on it. Someone take a look at http://www.potentiometers.com/ and see if anything comes up. There's some military grade stainless steel things there...

I'm switching out a buzzing woofer this week (voice coil wire separating from the coil and buzzing at low volume).

If anyone wants, I'll snap some photos of the upgrade

I did the restoration in 2003. Sorry to hear he's not around or is involved in other things. When we talked back then, he seemed to be developing some small high-end speakers for the consumer market ($$$).

Anyways, the kit came with high voltage polypropylene caps; 24/25uf for the mid, 6uf for the tweeter (Solens? I forget.) the pots were high grade, real smooth, but I forget the ohms (14 ohms is the old one, right?), and the manufacturer was not on it. Someone take a look at http://www.potentiometers.com/ and see if anything comes up. There's some military grade stainless steel things there...

I'm switching out a buzzing woofer this week (voice coil wire separating from the coil and buzzing at low volume).

If anyone wants, I'll snap some photos of the upgrade.

ES

[JKent]

Not familiar with CLR but I'm cautious about a chemical bath. I had good results with a wire wheel in my Dremel, followed by a coat of de-ox-it. Some use dielectric grease, which I plan to try next time. The pots are not hard to fix. I regret having put L-pads in my first restoration, fwiw.

[Guest SamS]

>Not familiar with CLR but I'm cautious about a chemical bath.

>I had good results with a wire wheel in my Dremel, followed by

>a coat of de-ox-it. Some use dielectric grease, which I plan

>to try next time. The pots are not hard to fix. I regret

>having put L-pads in my first restoration, fwiw.

I went looking for some dielectric grease last weekend, but came home empty. Can anyone point me in the right direction?

One tweeter has really started acting up again, makes a raspy, spitty sound. I have to turn it off. I'm dying to rip these things apart! Will have to wait until I have a few solid hours to start this project though. I'm like you..wanting to keep stock components. Will only use Lpads if pots are ruined.

FYI.. here's a link to CLR:

http://housewares.hardwarestore.com/35-176...ner-101851.aspx

This stuff just works so good getting chemical deposits off metal, I'm really tempted to try.

[Guest Bret]

Try an autoparts store. It comes in small pouches that look something like the ones that hold "lemon scented moist towelettes" at BBQ places. Usually about $1.00/pouch.

I like CLR, too, but I'm thinkin' this might not be the best idea for these pots. Wait until you get yours out and apart before you get too exotic. It's really pretty straight forward, just be gentle with it all, Dremel tool or sand paper. The oxidation will come off and if the old one's I've cleaned-up are any indication, they clean-up pretty easily. The only challenge is getting in the small spaces and that's where a wire-wheeled Dremel makes it go much faster (and potentially bends the crap out of stuff, so be really gentle).

Bret

[Carlspeak]

>>Not familiar with CLR but I'm cautious about a chemical

>bath.

>>I had good results with a wire wheel in my Dremel,

>followed by

>>a coat of de-ox-it. Some use dielectric grease, which I

>plan

>>to try next time. The pots are not hard to fix. I regret

>>having put L-pads in my first restoration, fwiw.

>

>I went looking for some dielectric grease last weekend, but

>came home empty. Can anyone point me in the right direction?

>

>One tweeter has really started acting up again, makes a raspy,

>spitty sound. I have to turn it off. I'm dying to rip these

>things apart! Will have to wait until I have a few solid

>hours to start this project though. I'm like you..wanting to

>keep stock components. Will only use Lpads if pots are

>ruined.

>

>FYI.. here's a link to CLR:

>

>http://housewares.hardwarestore.com/35-176...ner-101851.aspx

>

>This stuff just works so good getting chemical deposits off

>metal, I'm really tempted to try.

>

Sam. If you decide to replace, don't use l-pads. They are generally all 8 ohm and their bodies are too large to install them side by side at the nominal 1.25 inch center distance of the original rheostats.

Replace those bad rheostats with new ones. The old units where true rheostats, not l-pads. Attached are a couple of photos of the original Aetna-Pollack rheostats that have become corroded beyond repair and new, industrial grade 15 ohm units I offer to my customers. Visit my web site and look under crossover upgrades in my 'project gallery' section. You can see the new ones installed in an AR speaker.

http://www.classicloudspeakerservices.com/gallery.html

The wiper section of the new rheostats need some protection from fouling by the fiberglass stuffing. I posted some photos in the AR area a while back showing some simple wood covers I made and installed. Contact me directly regarding purchase of the new rheostats. I have some in stock for immediate shipment at nominal cost.

Remember, it's all about the music

Carl

Carl's Custom Loudspeakers

[Guest SamS]

Bret, thanks for the tip on the dielectric grease. I'll give it another shot tracking some down.

Carl, I appreciate your insight! I've heard that *someone* had replacement rheostats, and it turns out it must be you. Thanks for the links. I can't rip the speakers apart until next weekend, but you can bet I'll contact you with what I find.

[Guest Electrospark]

This jpg shows why any discussion about Deoxit is moot.

A soft wirebrush on a Dremel followed by a 1000 grit wet sand maybe?

I'd go for new pots.

ES

>

>Remember, it's all about the music

>

>Carl

>Carl's Custom Loudspeakers

[Carlspeak]

>This jpg shows why any discussion about Deoxit is moot.

>A soft wirebrush on a Dremel followed by a 1000 grit wet sand

>maybe?

>

>I'd go for new pots.

>

>ES

>

>

>

>>

>>Remember, it's all about the music

>>

>>Carl

>>Carl's Custom Loudspeakers

>

That jpeg is an extreme case. But, you never know what you'll find until you open them up. If you get some sound, albeit scratchy, there may be hope for cleaning them as es suggests.

Remember, it's all about the music

Carl

Carl's Custom Loudspeakers

[Guest SamS]

Hi Carl,

I don't see a pic in your post???

[dynaco_dan]

Hi there;

From here, scroll up a few messages and you'll see Carl's great photos.