AR-3a and AR-2x - just beginning

[Guest mdavis]

I have a pair of each of these speakers. They were both purchased new in 1970 and have never been subjected to excessive volume. In recent years, the pots seem to have corroded beyond use, and I am using the AR-3a's for the bass only, and the 2x's as rear surround speakers.

I would like to try to evaluate these speakers in terms of repairing (I hope) the pots. How likely is it that just the pots can be cleaned to bring back original performance? Storage has been at room temperature and normal humidity. Are the coils accessible on the pots, and can they be cleaned, or am I looking at a more difficult project? How likely are the caps to require replacement?

[Guest matty g]

Hi Mike -

The pots are cleanable if you remove the woofer and the fiberglass insulation behind it. Details on this and many, many suggestions on how to deal with this common problem are on numerous threads on this site - you have come to the right place. I would suggest using the search option on this page as a start, or just scroll down a bit.

Good Luck

Matt

[onplane]

>

>I would like to try to evaluate these speakers in terms of

>repairing (I hope) the pots. How likely is it that just the

>pots can be cleaned to bring back original performance?

>

Hi, Mike and welcome to best repository of information about AR speakers in the entire world.

Below are "mods" that in my opinion are the "low cost, permanent" solution to the pot problem. In addition to solving the problem these “mods” will move your speakers closer to a flat frequency response on modern media (CD’s, MP3’s, FM, etc). (If you listen to a lot of old vinyl, you’ll have to throttle back the treble control.)

Besides the mod, if you want to push these speakers to their maximum potential, you might consider bi-amping. First step, however, is to try the mods and see whether this gets all of the drivers working.

Regards,

Jerry

http://www.classicspeakerpages.net/dc/user_files/2056.jpg

http://www.classicspeakerpages.net/dc/user_files/2057.jpg

[Guest mdavis]

Thanks to both Mike and Jerry on this one. I am rather dense when it comes to doing electrical circuit board mods, but I think I can follow the diagrams Jerry posted. I don't want to change these speakers if I can avoid doing so, consequently I plan to begin by finding a tube of "electrical putty" for re-sealing the woofer and try just cleaning the pots. I don't know if they are easily accessible or must be removed from a board or .... I've never been inside either the 3a or the 2x. Apparently, pots are almost impossible to find for replacement.

There is so much information posted on this forum that it is a bit overwhelming. There are also a number of opinions as to what is a good "mod", which leaves me a bit puzzled, hence my intention to do the simple stuff first. "If it ain't broke ...." Problem is, I need to see what's "broke" first, so cleaning the pots is the first step. I can just barely find a "hot spot" on the pots on botht the 2X's and the 3a's that will allow sound from the mid-range/high speaker(s), so I'm hoping the other electronics are OK.

I have put this off much too long. I have an older Sony Dolby amp (not 5.1) and do not usually have the 2X's connected for the rear channels unless I want to watch a DVD. Since my old cable service has been mono sound only, I haven't done much with the rear speakers for a number of years. I recently switched to satellite with better sound, so I'm trying to get back up to speed.

I'll keep in touch. Thanks to both of you for the quick reply. It takes hours to read all the posts and archives.

[Guest crawlspace]

Jerry: Thankyou for providing the diagram on bypassing the pots. You provided a diagram earlier to me on how to wire up the biamping process.

As a novice, a picture is worth a 1000 words to me. Even though most discussions are way over my head, I do enjoy reading them and trying to figure out what is happening.

Thanks for the pictures.

Mike

[onplane]

Mike,

You certainly have a more difficult challenge. That is, "jerry-rigging" with a tube amp!!

Nothing easy about this at all and probably the most complex of setups.

Last I heard, Mike, you abandoned bi-amping for "pure tubing". I'd really be surprised if that Fisher unit can "punch out the bass" on your 3a's like your Yamaha.

So, Mike, how is it working?

Regards,

Jerry

[Guest mdavis]

Another simple question from a novice: are the caps shown the default (factory) caps, or do you assume installation of new caps with those specs? I haven't been into the speakers yet, having just found the sealeant I wanted to use to re-install the woofer.

Also, I had wanted to work on my 2x's before tackling the 3a's. Any comments on what to do with those first?

Also, is there a recommended method for cleaning the existing pots if I choose to go that way?

[johnieo]

>Also, is there a recommended method for cleaning the existing

>pots if I choose to go that way?

There are many posts on this site that describe how to clean and restore the Atena-Pollak potentiometers; the information is scattered and requires some effort searching. The pots are easy to take apart, clean and return to service. If your pots are severely corroded and beyond repair--as some but not all are--then one alternative is the purchase of new 16-Ohm, 25-W Ohmite pots.

New capacitors are in order, if their measured values are more than ten percent out of spec. The capacitor and pot comments apply to both models.

Although only a small number of CSP members respond to this common and very reasonable inquiry--simply because it is so common--the majority would suggest that the appropriate goal would be restoration to their original crossover and quantity/type of cabinet stuffing. In my opinion, DIY modifications (e.g. changing the crossover or biamping a three-terminal speaker) are inappropriate advice to one who is just beginning.

[johnieo]

There are two AR-3a crossover schematics: the AR factory crossover and the "Layne Audio" crossover. The Layne Audio schematic has the polarity of the mid/tweet set so that they are in phase with the woofer, whereas the AR-factory setting has them out of phase. This makes a difference in their sound at frequencies near woofer/mid crossover. Roy Allison, their designer, tested them both ways before deciding on which sounded best. If your speakers have never been modified, they will be wired as shown in the Archives (under AR-3a).

[Guest crawlspace]

Hey Jerry: I really enjoy my 1963 fisher system and AR3a's that I stumbled upon in December. The X202B amp, with the loudness contour button on really gives the speakers a good sound. I don't have to turn it up past the 10 or 11 oclock position to fill the house. That old amp does not disappoint. The bass, considering what I was listening to before, sounds good too. It rumbles through the house. Although, I think I know what you may mean when you say more power is needed. They seem to just want more.

I did my first technical enhancement to the system. I crimped spade clips to the speaker wires at the amp end and the speaker end. No more twisting wires for me. Don't know if it made a differnce in sound, but I feel a little proud of myself. (stop laughing now)

Thanks Mike

[onplane]

>There are two AR-3a crossover schematics: the AR factory

>crossover and the "Layne Audio" crossover. The Layne

>Audio schematic has the polarity of the mid/tweet set so that

>they are in phase with the woofer,whereas the AR-factory

>setting has them out of phase. This makes a difference in

>their sound at frequencies near woofer/mid crossover. Roy

>Allison, their designer, tested them both ways before deciding

>on which sounded best. If your speakers have never been

>modified, they will be wired as shown in the Archives (under

>AR-3a).

Hi, John

Maybe I'm NOT reading your post correctly, but it seems that you are saying the factory drawing shows the mid/tweet out of phase with the woofer. Am I missing something here, because they look in phase to me in the drawing below?

Now, on the phase issue of the mid/tweeter relative to the woofer, I have a little experience here. My HeathKit amp, which I initially used in my "jerry-rig", with had a tone defeat switch that reversed phase. This means that with a push of the button, I could alter the phase of the woofer relative to the mids/tweeters.

What I learned from using this switch (literally 100's of times) is that on some music I got better stereo imaging with the signal sent to both halves in phase. On other music, I got better imaging with the signal sent to both halves out of phase. Finally, on some music I could tell no difference whatsoever.

There was simply no way to predict how phase would impact sound in advance. Clearly this is NOT neat, nor is it what I expected.

From this experience, I believe that recording engineers in the mixing process can “screw up” phase, so that when I say I’m putting the music out of phase, in reality I’m simply undoing a mess created in the mixing process.

Regards,

Jerry

http://www.classicspeakerpages.net/dc/user_files/2076.jpg

[dynaco_dan]

Hi there;

The 3 drivers are in phase in that AR drawing.

The dot is the drivers positive terminal, which means that a positive signal to that terminal causes a forward movement of the cone.

Laynes drawing has the differential phasing.

[onplane]

>Hey Jerry: I really enjoy my 1963 fisher system and AR3a's

>that I stumbled upon in December. The X202B amp, with the

>loudness contour button on really gives the speakers a good

>sound. I don't have to turn it up past the 10 or 11 oclock

>position to fill the house. That old amp does not disappoint.

> The bass, considering what I was listening to before, sounds

>good too. It rumbles through the house. Although, I think I

>know what you may mean when you say more power is needed.

>They seem to just want more.

>

>I did my first technical enhancement to the system. I crimped

>spade clips to the speaker wires at the amp end and the

>speaker end. No more twisting wires for me. Don't know if it

>made a differnce in sound, but I feel a little proud of

>myself. (stop laughing now)

>

>Thanks Mike

>

That's just great, Mike! This is a fantastic hobby as there is ALWAYS:

1. something different to try

2. something to improve the ease of use

3. different placement of speakers to try

4. different combination of speakers

5. different amps/receivers

and the list goes on and on ....

Mike, for your next project you might try a bi-wire arrangement. Some people will tell you it does NOTHING, while others say they can hear an improvement. (I remain politically NEUTRAL.)

To bi-wire, you remove the strap between T and 2. Then you run a 2nd set of speaker cables from the Fisher to each speaker. (You could try on just one speaker, then using a mono source compare the sound from the two speakers.)

Most importantly, Mike, share with us what you hear.

Regards,

Jerry

[Guest mdavis]

I plan to attempt cleaning the pots first.

In going back through the back posts, I find references to Deoxit and "pens". Can someone enlighten me on what this is and where to find it (auto parts, electrical supply store, etc.).

Also, is there a specific di-electric grease that is recommended?

[joelongwood]

All you ever wanted to know about Deoxit:

http://store.caig.com/s.nl/sc.2/category.188/.f

I would venture a guess that any brand of di-electric grease would work to protect the pots from corrosion.