AR-3 crossover wiring

[zcon67]

Hi all,

I have learned alot here in AR land, still along way to go. Thanks to all for the info.

I just started this AR-3 project and have the wiring pictorial from the library. Some one has been in these before and

jumped the pots, different amounts of rockwool, etc.

The crossovers have only one choke, for the woof. No number. There is no 6mfd cap. I would like to pull the wax block

6&24 mfd caps. Questions: How to wire those 6&24 caps? Should there be another choke and what value? Should I install

the 6mfd cap as the drawing shows?

These have cast woofs, and only one has a serial #. It is C 55420.

Thanks, PeteZ

[JKent]

Hi all,

I have learned alot here in AR land, still along way to go. Thanks to all for the info.

I just started this AR-3 project and have the wiring pictorial from the library. Some one has been in these before and

jumped the pots, different amounts of rockwool, etc.

The crossovers have only one choke, for the woof. No number. There is no 6mfd cap. I would like to pull the wax block

6&24 mfd caps. Questions: How to wire those 6&24 caps? Should there be another choke and what value? Should I install

the 6mfd cap as the drawing shows?

These have cast woofs, and only one has a serial #. It is C 55420.

Thanks, PeteZ

Have you downloaded the excellent new booklet on restoring the AR-3a? Unfortunately, it is buried 'way down in the AR section of the Library, so here is the link:

http://www.classicspeakerpages.net/_Media/...the-ar-3a-2.pdf

I am not familiar with the AR-3, so wait for John or Roy or one of the other experts to reply, but based on my restoration of the 2ax, I think I can answer 2 of your questions: First--get rid of the rock wool and replace it with fiberglass (read the booklet referenced above--it will explain). Second--you may not have to pull the caps. If they are dual-value caps like in the 2ax, just cut the leads, leave them in place, and replace them with 2 separate good-quality caps of the correct value. I'll attach a couple of pics to illustrate. One shows the inside of an AR4x with the old cap left in plce. The other is a 2ax with the old cap removed. The Zen caps are no longer available. Carli and Solen from Madisound are popular, as are Dayton from PartsExpress. But the selection of capacitor brand seems to be a religion, with zealots on every side Again--read the booklet. It is unbelievable comprehensive and clear, and it was compiled by some true experts from this forum.

Good luck.

Kent

[zcon67]

Have you downloaded the excellent new booklet on restoring the AR-3a? Unfortunately, it is buried 'way down in the AR section of the Library, so here is the link:

http://www.classicspeakerpages.net/_Media/...the-ar-3a-2.pdf

I am not familiar with the AR-3, so wait for John or Roy or one of the other experts to reply, but based on my restoration of the 2ax, I think I can answer 2 of your questions: First--get rid of the rock wool and replace it with fiberglass (read the booklet referenced above--it will explain). Second--you may not have to pull the caps. If they are dual-value caps like in the 2ax, just cut the leads, leave them in place, and replace them with 2 separate good-quality caps of the correct value. I'll attach a couple of pics to illustrate. One shows the inside of an AR4x with the old cap left in plce. The other is a 2ax with the old cap removed. The Zen caps are no longer available. Carli and Solen from Madisound are popular, as are Dayton from PartsExpress. But the selection of capacitor brand seems to be a religion, with zealots on every side Again--read the booklet. It is unbelievable comprehensive and clear, and it was compiled by some true experts from this forum.

Good luck.

Kent

Thanks Kent for the pictures, they did help. I already have the booklet saved, it's a dandy and many thanks to those involved with that. I searched this forum for days finding info to redo my other speakers.

I have used Solen caps before and was pleased but it seemed to take along time for them to mellow. Do you use them?

Thanks again, PeteZ

[johnieo]

Hi all,

I just started this AR-3 project and have the wiring pictorial from the library. Some one has been in these before and

jumped the pots, different amounts of rockwool, etc.

The crossovers have only one choke, for the woof. No number. There is no 6mfd cap. I would like to pull the wax block

6&24 mfd caps. Questions: How to wire those 6&24 caps? Should there be another choke and what value? Should I install

the 6mfd cap as the drawing shows?

These have cast woofs, and only one has a serial #. It is C 55420.

Thanks, PeteZ

Pete: Let's make sure we are on the same wavelength. You have AR-3 correct? not AR-3a? If so there were two crossover circuits. The original AR-3 had one inductor in the woofer circuit labeled "143 Turns" (0.4 mH) that is not the AR #7 coil. The #7 is 1.88 mH. That circuit used a only 24 uF midrange cap and a only 6 uF tweeter cap. If polypropylene caps are in your cabinets, you might try adding about a half Ohm in series with each to replicate the original capacitor's characteristic. In 1974 near the end of production, I am told that AR ran out of the original midrange and used a variant of the AR-3a midrange. That required a crossover change. which is illustrated in the modified drawing in the archives. I believe C was increased and a second coil was added. These two AR-3 midrange drivers are illustrated in the appendix of the AR-3a restore manual- they were put there to help in identification specifically because eBay purchases often have swapped drivers. The early AR-3 would have the midrange numbered A.9 in the appendix, whereas the later AR-3 (after 1974) would have the special midrange numbered A.10 in that appendix. If you check to see which mid you have, you will know what crossover circuit to use.

You are dealing with the two problems common to many AR speakers: design changes in mid-production, and buying used equipment that may have been incorrectly altered by a prior owner. Taken together, they make strong coffee a prerequisite to understanding. So go make coffee :-)

Cheers,

John

[zcon67]

Pete: Let's make sure we are on the same wavelength. You have AR-3 correct? not AR-3a? If so there were two crossover circuits. The original AR-3 had one inductor in the woofer circuit labeled "143 Turns" (0.4 mH) that is not the AR #7 coil. The #7 is 1.88 mH. That circuit used a only 24 uF midrange cap and a only 6 uF tweeter cap. If polypropylene caps are in your cabinets, you might try adding about a half Ohm in series with each to replicate the original capacitor's characteristic. In 1974 near the end of production, I am told that AR ran out of the original midrange and used a variant of the AR-3a midrange. That required a crossover change. which is illustrated in the modified drawing in the archives. I believe C was increased and a second coil was added. These two AR-3 midrange drivers are illustrated in the appendix of the AR-3a restore manual- they were put there to help in identification specifically because eBay purchases often have swapped drivers. The early AR-3 would have the midrange numbered A.9 in the appendix, whereas the later AR-3 (after 1974) would have the special midrange numbered A.10 in that appendix. If you check to see which mid you have, you will know what crossover circuit to use.

You are dealing with the two problems common to many AR speakers: design changes in mid-production, and buying used equipment that may have been incorrectly altered by a prior owner. Taken together, they make strong coffee a prerequisite to understanding. So go make coffee :-)

Cheers,

John

Hi John,

I believe these are the original drivers and the caps have not been replaced. The woof is the A1 and the mid is the A9. Only one inductor on the woof and missing the 6uf cap. There are two diagrams in the library both it seems have these in the circuit. The one with the notes was hard for me to read so I printed the other. Do I just leave out those loops?

I need another sip of coffee!

Thanks, Pete

[johnieo]

Hi John,

There are two diagrams in the library both it seems have these in the circuit. The one with the notes was hard for me to read so I printed the other. Do I just leave out those loops?

I need another sip of coffee!

Thanks, Pete

Pete:

It is my understanding that the circuit diagram containing the hand-written notes is a difficult-to-read sketch of how to modify the AR-3 crossover to accommodate the "special" midange made after '74. If this is not correct, Tom Tyson or someone else can correct.

Cheers, and good luck. ps: you might well want to change those very old caps, but if you do use polypro please add some series R as noted earlier.

John

[RoyC]

Pete,

I agree with John. The Library schematics are confusing. Your crossover is likely the earliest version, before the addition of the inductor or the 6uf cap. I saw one last year just as you describe.

I also agree that the caps should be replaced. The caps in my specimens were way off.

Are the serial number labels still attached to the back of the cabinets?

Roy

[Diamonds&Rust]

I have used Solen caps before and was pleased but it seemed to take along time for them to mellow. Do you use them?

You are the third or fourth person to notice this. I was able to get them a great deal mellower by using a .22uF by-pass capacitor (which I only did in desperation). They immediately lost 95% of their offensiveness. Two years (and many hundreds of hours of play) later they no longer have that nastiness to them at all. In fact, they sound just great.

Although others have reported having no trouble at all with them, I will never use them again on a midrange or tweeter and I will never use them anywhere without a by-pass capacitor.

This is just an opinion based on a very limited number of experiences - so take this for what it is worth (maybe nothing) - but for the tweeter capacitor I would use a poly paralleled with a much smaller film-and-foil. There is no reason to spend mega-dollars on caps for an AR-3 tweeter, but for good results spend the extra $3.00 for by-pass caps OR just use new non-polar electrolytics. Either way I'm guessing you should be happy. I do not like poly-only on AR tweeters and film and foil by itself is much more expensive and only marginally different; leaning toward a "brittle" sound.

Is that my imagination? Probably. But for $3.00 or so it can be my imagination and I'm going to do it to keep my anxiety closet's door shut.

However, I will tell you that I would quickly bow to Roy's opinion. He has a great deal more experience than I do. I trust his ear for "good" as much or more than I would measurements with lab gear, and I have *never* re-capped a crossover using *that* specific tweeter. I think you might run that tweeter into trouble if you don't feed it just right.

[zcon67]

You are the third or fourth person to notice this. I was able to get them a great deal mellower by using a .22uF by-pass capacitor (which I only did in desperation). They immediately lost 95% of their offensiveness. Two years (and many hundreds of hours of play) later they no longer have that nastiness to them at all. In fact, they sound just great.

Although others have reported having no trouble at all with them, I will never use them again on a midrange or tweeter and I will never use them anywhere without a by-pass capacitor.

This is just an opinion based on a very limited number of experiences - so take this for what it is worth (maybe nothing) - but for the tweeter capacitor I would use a poly paralleled with a much smaller film-and-foil. There is no reason to spend mega-dollars on caps for an AR-3 tweeter, but for good results spend the extra $3.00 for by-pass caps OR just use new non-polar electrolytics. Either way I'm guessing you should be happy. I do not like poly-only on AR tweeters and film and foil by itself is much more expensive and only marginally different; leaning toward a "brittle" sound.

Is that my imagination? Probably. But for $3.00 or so it can be my imagination and I'm going to do it to keep my anxiety closet's door shut.

However, I will tell you that I would quickly bow to Roy's opinion. He has a great deal more experience than I do. I trust his ear for "good" as much or more than I would measurements with lab gear, and I have *never* re-capped a crossover using *that* specific tweeter. I think you might run that tweeter into trouble if you don't feed it just right.

Hi John, Roy, and Bret.

Thanks for responding. As you can tell I am electronically challenged but doing the best I can.

These speakers are made the same in every way so I will assume they have always been a pair. Only one serial # is attached: #c 55420. From searching for numbers I think they might be from 1964 or 5. Neither inductor is labled and only one dbl wax cap is labled: 6 & 24 mfd. I will assume the other has the same value. One leed on a mid was broken about midway and someone tried to twist it together which, of course didn't work. I have soldered another but from reading here these are the aluminium. I will read that section again to make sure I do that right.

On the good side the 4 pots were in respectable condition and cleaned up as suggested. Cabs not to bad for this age (kinda like me) and should look presentable. Grills were replaced w/ plastic frames and ugly cloth so will replace them.

I am planning on replacing those caps and relying on this forum for the best possible sollution without causing a frey.

Thanks again for your kind and speedy posts. PeteZ

[Diamonds&Rust]

Grills were replaced w/ plastic frames and ugly cloth so will replace them.

Be sure you aren't pitching-out the original grills and frame.

If the frame is little-bitty thin plastic, that might well be the original frames. If they aren't broken, it's a miracle. The ugly cloth wouldn't happen to be nylon, sort-of a nasty beige color, that feels like woven fishing-line? If all those things are true, congratulations! Well, sort-of congratulations, because now you have a dilemma.

I think all of us who have experienced the authentic, really old, grills would say they just don't stand-up, beauty-wise, to the later linen.

On the other hand, those old plastic-feeling grills are more rare; and not by a small margin.

So the dilemma is: Do I, A) keep the original grills on the speaker and know how really cool it is that I still have these, or replace them with something I'd rather look at?

I any event, if you have original grills and place any value (as a collector might) on authenticity and true "original condition," or feel like you may sell them to a collector one day, even if you can't stand to look at them, *keep* the original frames and grills in a box somewhere.

And if none of it is original, the choice becomes easier.

Bret

[zcon67]

Be sure you aren't pitching-out the original grills and frame.

If the frame is little-bitty thin plastic, that might well be the original frames. If they aren't broken, it's a miracle. The ugly cloth wouldn't happen to be nylon, sort-of a nasty beige color, that feels like woven fishing-line? If all those things are true, congratulations! Well, sort-of congratulations, because now you have a dilemma.

I think all of us who have experienced the authentic, really old, grills would say they just don't stand-up, beauty-wise, to the later linen.

On the other hand, those old plastic-feeling grills are more rare; and not by a small margin.

So the dilemma is: Do I, A) keep the original grills on the speaker and know how really cool it is that I still have these, or replace them with something I'd rather look at?

I any event, if you have original grills and place any value (as a collector might) on authenticity and true "original condition," or feel like you may sell them to a collector one day, even if you can't stand to look at them, *keep* the original frames and grills in a box somewhere.

And if none of it is original, the choice becomes easier.

Bret

Hi Bret,

Sorry these were not the original. They were probably broken when they were entered before. The frames were a kit you can snap together and the cloth bad shape and hot glued on. Not to keen. Oh well, if I can get these together and sounding good again I'll be happy. The cosmetics will come along sometime.

Thanks, PeteZ

[RoyC]

You are the third or fourth person to notice this. I was able to get them a great deal mellower by using a .22uF by-pass capacitor (which I only did in desperation). They immediately lost 95% of their offensiveness. Two years (and many hundreds of hours of play) later they no longer have that nastiness to them at all. In fact, they sound just great.

Although others have reported having no trouble at all with them, I will never use them again on a midrange or tweeter and I will never use them anywhere without a by-pass capacitor.

Although the capacitor conversation is always a dangerous one, Bret, John, and I do seem to agree on some things :-).

Rather small variations in series resistance, capacitance and, maybe, inductance can be audible depending on the listener and circumstances. My take is that most folks more or less get used to these variations over time (which can also be perceived as new caps "breaking in"). Many folks will not notice or care about such "differences", especially if they don't have a reason or the means to directly compare the results against the original version of the speaker system.

With that said, adding a small amount of series resistance, and a small parallel capacitor, seems to have a smoothing out effect on new film caps when they are being used to replace old electrolytics. The original capacitor, no doubt, had higher esr/series resistance, and probably higher capacitance as it drifts out of spec, resulting in a lowering of the crossover point (probably among other things). Adding some of both to the new cap may bring the sound closer to what the listener was used to with the old caps, or maybe even closer to the original design spec. That is not to mention the possible effect of differences in phase or inductance created by adding a resistor and another cap to the mix.

When replacing old electrolytic caps "as authentically" as possible, I personally prefer to stray slightly on the high side of the original value, (a .2 to .3 uf parallel cap is a good way to do that), and add a .3 +/- ohm resistor in series. I'm not as sold as the other guys on the overall sonic impact of doing this for anything but the tweeter circuit.

One thing I have NOT heard, generally speaking, is audible improvement as the price of the capacitor increases. Reasonably priced Solens, Parts Express Daytons, and Madisound surplus and Carli mylars all respond well, IMO, to the circuit modifications described above.

Roy

[Diamonds&Rust]

My take is that most folks more or less get used to these variations over time (which can also be perceived as new caps "breaking in").

Well, you and Carl and I may have to engage in a duel someday over this issue. These capacitors *change* over time. When you have multiple speaker sets (as you know) and multiple "systems" to listen to them on, and "reference" recordings, and a "reference" pair of speakers (unchanging) against-which to judge, then the capacitor's change is quite obvious.

But with differences in sources, amplification, and hearing, I doubt we will *ever* be able to quantify this by listening. <Where's Ken and all that expensive test gear when you need him?>

One thing I have NOT heard, generally speaking, is audible improvement as the price of the capacitor increases. Reasonably priced Solens, Parts Express Daytons, and Madisound surplus and Carli mylars all respond well, IMO, to the circuit modifications described above.

Haven't tried all those. I'll take your word for it. Don't you have the wherewithall to test for phase changes?

Bret

[RoyC]

Well, you and Carl and I may have to engage in a duel someday over this issue. These capacitors *change* over time.

Hey Bret,

Well, film caps are not likely to "change" as readily as electrolytics do (which is the main reason to use them), and we are typically talking about 30 to 40 year old drivers (and, at least in my case, ears that are even older). It is hard enough to find ANY two of these things that have remained unchanged, and that's not taking into account OTHER peoples's ears :-)!

As for having the wherewithall to measure phase, I have my hands full determining the phase of the moon !

...as I said, dangerous territory, and, assuming a cap of the appropriate value is utilized, not nearly as relevant to *most* people as literally every other concern of a typical restoration, including deteriorating drivers, corroded level controls, poor surround repair and treatments, and crappy replacement drivers.

Roy

[zcon67]

Hey Bret,

Well, film caps are not likely to "change" as readily as electrolytics do (which is the main reason to use them), and we are typically talking about 30 to 40 year old drivers (and, at least in my case, ears that are even older). It is hard enough to find ANY two of these things that have remained unchanged, and that's not taking into account OTHER peoples's ears :-)!

As for having the wherewithall to measure phase, I have my hands full determining the phase of the moon !

...as I said, dangerous territory, and, assuming a cap of the appropriate value is utilized, not nearly as relevant to *most* people as literally every other concern of a typical restoration, including deteriorating drivers, corroded level controls, poor surround repair and treatments, and crappy replacement drivers.

Roy

Hi all,

I have reread all these posts and will take your advice on the bypass caps and series R. I am compileing an order that should be ready soon. With the holidays approching we will see how much work gets done.

I think it's happy hour right now. Here's to you. Thanks, PeteZ