Repairing AR3-Speakers?

[Guest Dodger]

Hi everybody.

I just got original (tweeters replaced) 2 AR3 Speakers from my father. I set them up and was amazed by the sound! Nevertheless there are some questions that rose:

1. The Woover Cones have some small cracks towards the inside. does that hurt? do i have to fix them? they still sound quite nice...

2. The pots for mid and hi are corroded and only make contact on the hightest setting. can i put cheap replacements in (i think they are 14ohm) or do i have to buy special ones (at layne-audio)? should i just short them?

3. is there any need to replace the capacitors? (just because they are quite old...)

4. should i change the phase of the mid-speaker to get better mid-ranges?

thanx in advance for the help.

greetings

dodger

(im from switzerland, so forgive me typos, grammatical errors and so on... )

[Guest Brian_D]

>I just got original (tweeters replaced) 2 AR3 Speakers from my

>father. I set them up and was amazed by the sound!

>Nevertheless there are some questions that rose:

Congrats. Those are great speakers.

>3. is there any need to replace the capacitors? (just because

>they are quite old...)

MUCH debate about this one... Read the threads related to the AR90 crossover upgrade and the more recent "voicing" thread.

>4. should i change the phase of the mid-speaker to get better

>mid-ranges?

I'm not really sure why changing the phase of the midrange would improve your mid-range response unless they are currently incorrectly wired out of phase. In fact, if you do reverse the phase you're almost assuredly going to cause more problems than you fix. The waveform from the speaker will be attenuated at the crossover frequencies, a result of in-phase and out-of-phase frequencies being emitted from different drivers.

If you're not happy with the mid-range response of the speaker (which I'm sure could be improved by the repair/replacement of the pots) perhaps an EQ is in order. Is there a problem with the sound of the speaker?

[Guest dogmeninreno]

>Hi everybody.

>I just got original (tweeters replaced) 2 AR3 Speakers from my

>father. I set them up and was amazed by the sound!

>Nevertheless there are some questions that rose:

>

>1. The Woover Cones have some small cracks towards the inside.

>does that hurt? do i have to fix them? they still sound quite

>nice...

>

>2. The pots for mid and hi are corroded and only make contact

>on the hightest setting. can i put cheap replacements in (i

>think they are 14ohm) or do i have to buy special ones (at

>layne-audio)? should i just short them?

>

>3. is there any need to replace the capacitors? (just because

>they are quite old...)

>

>4. should i change the phase of the mid-speaker to get better

>mid-ranges?

>

>thanx in advance for the help.

>

>greetings

>dodger

>(im from switzerland, so forgive me typos, grammatical errors

>and so on... )

>

>4. should i change the phase of the mid-speaker to get better

>mid-ranges?

>I wonder, Are you referring to the woofer being wired 180 degrees out of phase with the mid/tweeters on the AR3a's by the factory? I have not heard of this being an issue on the AR3's.

1. The Woofer Cones have some small cracks towards the inside.

>does that hurt? do i have to fix them? they still sound quite

>nice...

If the woofers are the older alnico bolted on magnet type, The center dampning ring will normally show cracks. I have not been able to hear any difference and would probably leave them alone. Some people use a product called "Armorall" which is made for automotive dashboards and spray it on their woofer cones.

2. The pots for mid and hi are corroded and only make contact

>on the hightest setting. can i put cheap replacements in (i

>think they are 14ohm) or do i have to buy special ones (at

>layne-audio)? should i just short them?

Clean your pots and leave them original. There are many threads regarding the procedure on this forum. Good luck and keep us posted? Dale

>

[Guest Dodger]

thanx for the replys.

it seems that i confused the ar3 with the ar3a about mid-range-out-of-phase-problem. thats why i will leave the wiring because i am quite satisfied with the mid range, once the pots make contact.

if it suffices to clean the pots i will first try to do this before replacing them with new ones! thanx for the tip, this will sure be cheaper and easier than buying new ones.

i'll keep you posted on how all worked out.

greetings

Dodger

[tysontom]

>thanx for the replys.

>

>it seems that i confused the ar3 with the ar3a about

>mid-range-out-of-phase-problem. thats why i will leave the

>wiring because i am quite satisfied with the mid range, once

>the pots make contact.

>

>if it suffices to clean the pots i will first try to do this

>before replacing them with new ones! thanx for the tip, this

>will sure be cheaper and easier than buying new ones.

>

>

>i'll keep you posted on how all worked out.

>

>greetings

>Dodger

>

>

Dodger,

AR did wire the 3-way speakers out-of-phase intentionally after some work was done in the anechoic chamber that determined that response was smoother at crossover being done that way. Some anomolies were noticed in the response testing, and then listening tests confirmed what they had measured, and that is when the phase changes were initiated. Those differences were very, very subtle, incidentally, so no gross changes occurred, and these differences were barely audible in the reverberant sound field back away from the speakers themselves. Therefore, if your speaker has *not* been changed or modified, or had driver replacement by someone other than the factory, everything will still be fine, I would not worry about it (you will not want to make any changes to phasing if everyhthing is original as it appears to be in your case). Incidentally, this dc polarity change first occurred in the AR-3 somewhere in the early 60s, and followed with the other 3-way speakers going forward. To be expected (and normal), there is a lot of overlap in response in the crossover regions with each driver in the AR-3 and AR-3a, and this accounted for some effects that were detected in the anechoic chamber.

With regard to the level controls, if you do get contact at some point in turning the knobs back and forth, I would not contemplate replacing them. Sometimes you can turn the speakers face down, and carefully spray contact cleaner down the shaft of each level control, then turn the controls back and forth a lot, and sometimes you can get a slight improvement in contact. The ideal setup would be to get output on the mid control at the "dot" position, and output at or near maximum on the super tweeter control, but anything approaching this is probably fine. After you turn them back and forth, you have to put your ear close to driver and very slowly move the control until you hear the driver's response come in and out. This takes great patience. The other alternative is to remove the level controls altogether, and this is a tedious project, but usually well worth the effort if the controls cannot be brought back to life by turning them back and forth.

--Tom Tyson

[Guest Dodger]

tom,

thank you for your inightful info on the phasing-issue with ar3-speakers. it will probably be better to leave the wiring at its original layout...

as for your idea regarding the pots: i will definetly try your approach before opening the whole speaker (which will be quite messy due to the glass fiber stuffing, as i read).

its great to find such a nice forum full of helpful people!

regards

Dodger

[stan461]

I am in the middle of replacing the pots on a pair on AR3As.

I tried cleaning them but that didn't work. In fact I opened the speakers up and took out the controls and cleaned them and bent them a little to establish a better contact.

Replacing them was and is a tedious task. No rocket science here, just a lot of patience.

The woofes are a real pain to get out. The gasket they used makes an exceptional seal which is hard to break. I made a little tool to scrape around and underneath the woofer just to get it free.

Once you are in there its de-soldering and then soldering in a tight spot.

I also discarded the stuffing that was in there, vacuumed it out good and then and re-stuffed it with Acousta Stuf.

I know it seems like a lot of trouble but the mids and highs just kept cutting out without touching the controls.

Here is the EMail address of the gentleman I bought the new pots from:

Ljlagace@aol.com

[johnieo]

>3. is there any need to replace the capacitors? (just because

>they are quite old...)

In my opinion that depends on the kind of capacitors used in the AR-3 units you own. The early AR-3 s/n 11,xxx) used metal can, oil-filled for the 24-uF cap (20 in parallel with 4)--don't know what was used for the 6 uF. A later AR-3, s/n 68,xxx used an Industrial Condenser Corp. inpregnaged paper dual 24- and 6-uF. (I posted some data on older caps in a different thread, and have added here some dielectric absorption measurements for the heck of it.) It is hard to say what the as-manufactured ESR's were--that depends on the type of dielectric liquid.

If your speaker has the metal can, oil-filled units, I would not feel the need to run to the store and purchase replacements. However, if they contain impregated paper caps encapsulated in wax, then I would consider replacement a necessity. The dissipation factor (equiv. series resistance) can change with life (moisture in or liquid out). I was quite surprised by how stable the metal-encapsulated units have remained since manufacture. Not so with IDC wax-filled paper boxes!

The DF value affects the crossover charactersitic. Most likely, the DF's of new polypro metal-film caps will be a factor of a hundred less than any other replacement type; therefore these would alter crossover properties far more than would new paper, oil or non-polar electrolytic. I belive Tom Tyson stated elsewhere that the crossover in the AR-3 was a bit fussy and not something with which one should tamper.

Happy rebuilding!

[Guest Dodger]

hi all.

i just used a lot of contact spray on my old pots. after turning around the knobs maaaany times and letting dry out the solvant, the pots are working again!!!

thanks for the tip about that, this was much more hassle-free than opening the caskets.

greetings

dodger

[Guest Bret]

>If your speaker has the metal can, oil-filled units, I would not feel the need to run to the store and purchase replacements. However, if they contain impregated paper caps encapsulated in wax, then I would consider replacement a necessity. <

John, I'm really glad you are putting numbers to these measurements.

My experience with this pair of AR-90s is not exactly the same as with your 3a's.

In the 90s, one of the caps that seems to be going bad is an aluminum can. I don't have the part#, but it's an 80uF 100V can.

I'm beginning to think we ought to determine suitable replacements for every cap in every cabinet. I just don't know how we'd ever do that without the historical data we lack.

Bret

[johnieo]

>>If your speaker has the metal can, oil-filled units, I would

>My experience with this pair of AR-90s is not exactly the same

>as with your 3a's.

>>In the 90s, one of the caps that seems to be going bad is an

>aluminum can. I don't have the part#, but it's an 80uF 100V

>can.

Bret:

One issue is my sloopy definition of "metal can." I was refering to the steel cans used in oil-filled capacitors, not the aluminum cans for non-polar electrolytics. I apologize for being unclear.

This may also be confusing, since some may assume that all AR-3 used the same capacitor type. Not so.

It would seem that AR used oil-filled, steel-can-encapsulated capacitors in its early AR-3 speakers, then later changed to impregnated paper caps sealed in wax. AR-3a begin production using impregnated paper, wax-sealed caps and then later switched to non-polar electrolytics. It makes one think that technical specs other than the capacitance value were not considered when making purchasing decisions. Perhaps price was the issue? (One sees a long-term trend from oil-filled to paper to NPE.)

Since the original query related to the AR-3, I commented that if his units are early AR-3 production models containing the steel-encased capacitors, I would not consider replacement a high priority. However, if his units are later AR-3 models containing the wax-paper-encased units, then I would put replacement at the top of the list.

The steel cans seemed to be rather well sealed at the terminals, and allowed little leakage out or permeation in. The wax encased units will suffer from low-level, long term permeation through the wax and leakage where the wires exit. Dry NPE's can suffer long-term degradation by many mechanisms: slow water vapor influx at the insulator-can seal, low operating voltage (or long term storage) causing the aluminum anodic oxide to become thinner (C increase), and so on. Temperature increase due to heat generated by power dissipated in the ESR will also decrease lifetime. Many issues ... some of which may relate to the voltage-current conditions an NPE sees in a particular location in a particular crossover circuit. Modern plastic encapsulated polypropylene-film caps should be rather stable for the long term--stable material, good encapsulation. Hope this clarifies things a bit.

[Guest Bret]

>One issue is my sloopy definition of "metal can." I was refering to the steel cans used in oil-filled capacitors, not the aluminum cans for non-polar electrolytics. I apologize for being unclear.<

Nah, ain't your fault. Mine. I didn't realize there was a difference. I haven't been inside a 3a in so long I don't remember how long it's been.

Bret