Upcoming AR3a project

[fran604g]

Your tweeter pot is correct, and your mid pot is not typical. It is unfortunate we used that confusing photo in the restoration guide.

Do you have the original brown control knobs? If so, don't worry about the difference. Adjust them accordingly and nobody but you will know.

There is obviously a reason you have an "old" indentation in the appropriate location.

Roy

Hi Roy,

I just re-read the recent threads and noticed I missed your question, sorry. The knobs on both units are black, the shafts are red on the pots in SN 3A-04125 and black in SN 45696, is it possible that the original mid range pots had the locating tabs on the other side of the pot? Do you know of any pictures showing pots that are different than mine. Not a big deal, I'm just very curious now about these 3a's that I have and would like to discover any historical evidence pertinent to them.

Thanks, Fran

[RoyC]

Hi Roy,

I just re-read the recent threads and noticed I missed your question, sorry. The knobs on both units are black, the shafts are red on the pots in SN 3A-04125 and black in SN 45696, is it possible that the original mid range pots had the locating tabs on the other side of the pot? Do you know of any pictures showing pots that are different than mine. Not a big deal, I'm just very curious now about these 3a's that I have and would like to discover any historical evidence pertinent to them.

Thanks, Fran

Hey Fran,

The knobs were usually a very dark brown...whatever, glad you have them.

The pot tabs of the AR models of the 3a era did not vary. I have only seen differences in the shaft material and wipers. Your serial numbers would have had the pots installed in the conventional way. I have been inside too many 3a cabinets to believe otherwise. Your "old" indentation is the clue to the way they "should" have been originally manufactured.

Btw, your 3a-04125 specimen would have originally been equipped with a cloth surround woofer. Unless someone switched it out along the way, that cabinet has the smaller #7 (1.88mh) inductor in the crossover. The #9 (2.85mh) inductor should be used with the foam surround woofer....and, yes, there is an audible difference. This is a bigger issue from a practical and historical perspective than the pot tabs.

Roy

[fran604g]

Hey Fran,

The knobs were usually a very dark brown...whatever, glad you have them.

The pot tabs of the AR models of the 3a era did not vary. I have only seen differences in the shaft material and wipers. Your serial numbers would have had the pots installed in the conventional way. I have been inside too many 3a cabinets to believe otherwise. Your "old" indentation is the clue to the way they "should" have been originally manufactured.

Btw, your 3a-04125 specimen would have originally been equipped with a cloth surround woofer. Unless someone switched it out along the way, that cabinet has the smaller #7 (1.88mh) inductor in the crossover. The #9 (2.85mh) inductor should be used with the foam surround woofer....and, yes, there is an audible difference. This is a bigger issue from a practical and historical perspective than the pot tabs.

Roy

That's interesting, maybe whoever swapped the tweet and mid drivers changed woofers, too. Do you know how much of a frequency change the inductor would make? I have no way of measuring the speakers. I did notice a difference between the 2, but it was the high and mid freq. that sounded more attenuated in the other one. I don't notice a difference with the bass between them.

[RoyC]

That's interesting, maybe whoever swapped the tweet and mid drivers changed woofers, too. Do you know how much of a frequency change the inductor would make? I have no way of measuring the speakers. I did notice a difference between the 2, but it was the high and mid freq. that sounded more attenuated in the other one. I don't notice a difference with the bass between them.

The woofer in the cabinet with the earlier #7 coil will extend further into the midrange frequencies. The cloth surround woofer did this better than the foam surround version, and is more versatile. It does well with either coil, but the foam surround woofer exhibits some midrange issues with the smaller coil. Your cabinet # 04125 has the 1967 to 1969 crossover discussed above.

Roy

[fran604g]

The woofer in the cabinet with the #7 coil will extend further into the mudrange frequencies. The cloth surround woofer did this better than the foam surround version, and is more versatile. The cloth surround woofer does well with either coil, but the foam surround woofer exhibits some midrange issues with the earlier, smaller coil. Your cabinet # 04125 has the 1967 to 1969 crossover discussed above.

Roy

Thanks, Roy, that explains why it sounded a little brighter to me than the other one.

I looked at my photos and the cab # 45696 has a #9, #3A-04125 doesn't have any marking on it. How can you tell if it is a #7?

[RoyC]

Thanks, Roy, that explains why it sounded a little brighter to me than the other one.

I looked at my photos and the cab # 45696 has a #9, #3A-04125 doesn't have any marking on it. How can you tell if it is a #7?

The best way to determine the inductor value is with an LCR meter. The #9 inductor will measure around 2.85mh. Alternatively, if the diameter and depth of the wire spool of the known #9 coil is the same as the unmarked one, the unmarked one is probably a #9 coil as well. The #7 spool of wire is slightly smaller.

From here it looks like your unmarked coil may be a #9. If it is, I believe 04125 was repaired early in the game at the factory or an authorized repair shop. It would explain your early foam surround woofer as well as the skewed pot re-installation.

Roy

[fran604g]

Thanks again, Roy, that's very encouraging for me to hear!

I was just reading up on measuring mH and that's something I am not currently able to do. At some point I will take physical measurements and see if I can get a buddy of mine to measure it for me.

[JKent]

The woofer in the cabinet with the earlier #7 coil will extend further into the midrange frequencies. The cloth surround woofer did this better than the foam surround version, and is more versatile. It does well with either coil, but the foam surround woofer exhibits some midrange issues with the smaller coil. Your cabinet # 04125 has the 1967 to 1969 crossover discussed above.

Roy

Interesting info Roy. So when I converted my AR-3 to 3a, I used the #9 coil even though the speakers have the AR-3 cloth surround woofers. Is that OK or would the #7 be better? As you know, I'm using AR-11 mids.

Kent

[RoyC]

Interesting info Roy. So when I converted my AR-3 to 3a, I used the #9 coil even though the speakers have the AR-3 cloth surround woofers. Is that OK or would the #7 be better? As you know, I'm using AR-11 mids.

Kent

Hi Kent,

The cloth surround woofer is OK with either coil. The primary issue is the response of the foam surround woofer at higher frequencies. The #9 coil rolls it off sooner to minimize this.

Roy

[fran604g]

So I guess that I'm done with my new latest favorite speakers! SN 45696 looks like new, SN 3A-04125 is not quite as nice, but still very, very nice.

A couple of pictures of my cleaned and oiled (finished for now ) AR3a's.

A very sincere "THANK YOU" to everyone that helped me get to the conclusion of a great project.

[fran604g]

BTW: After ~30 hrs. play time, they've really opened up. Both are very well balanced in the bass, mids and highs, now. The pot settings are very close for each speaker.

My preference is with both the mid and high pots slightly increased from the white dot settings, probably because I am used to listening to my 604's which sound a bit more extended in the high and mid frequencies than the 3a's.

[fran604g]

Another update:

My listening experience with my 3a's is really coming into focus now.

The soundstage is very wide and tall. The speakers disappear with Dire Straits, "Brothers in Arms" on vinyl (Warner Bros. 1-25264) and "Dire Straits" on CD (Warner Remasters, Produced by Muff Winwwod, 9 47769-2)

I think the highs are stunning, accurate and smooth. Cymbals sound like cymbals, with no sibilance to my ears. The mid range is smooth and accurate with both female and male vocals being extremely lifelike, not quite as accurate as my 604's, with just a touch of warmth.

The bass, as anyone that's heard 3a's will tell you, is strong, authoritative, tight and deep, with no flabbiness whatsoever.

They are also very revealing, with crappy recordings being instantly recognizable, not unlike my 604's in that regard.

In the "sweet spot," the stereo imaging and separation is superb. Even when I'm sitting slightly off center in a chair, I can pick up on the separation with distinct left and right channels, the way it was recorded/mixed. Whereas my 604's can be a bit narrow in this regard.

Off axis listening is particularly notable. When listening from an adjacent room, the depth and clarity is remarkable. Although there is no "stereo" effect, obviously, I am drawn in to the incredible soundstage.

The 604's are better at reproducing much louder sounds (they're listed in Altec Lansing's Brochure at 100 dB SPL sensitivity) for "whole house" off axis far-field listening, whereas my 3a's, because of the slightly warmer mid range, are my new choice for near-field listening...at least for now.

[xmas111]

Glad your happy with your 3a's!

I truly enjoy mine. Can't wait to finish my second pair and give them a try stacked.

They are great speakers that should give you many years of listening pleasure.

BTW, you did an excellent restoration on them.. you should be very proud.

John

[fran604g]

Thanks John, I am very proud of the work, but much happier with the sound

I would LOVE to be able to stack a pair! That would be incredible. I stacked a pair of OLA's with KLH 6's on top, vertically, with the tweets in the middle. They blew me away! I can't imagine what the 3a's stacked would be like. Or your LST's for that matter.

Maybe I'll get lucky

[fran604g]

Hiya folks,

 

It's been about 6-1/2 years since I last visited this thread, but the pots I resurrected in the fall of 2012 have been giving me fits for about 6 months or so, so I need to get inside the cabinets again. This time I'm replacing them all with new ones from "captainfantastic07" on eBay. I placed the order yesterday, so over the upcoming days or weeks, I'll once again photo-document my experience here.

I'll keep the original pots with my AR3a's for posterity.

I also fixed those pesky broken linked photos from my earliest posts in this thread.

Cheers!

Fran

[JKent]

7 minutes ago, fran604g said:

This time I'm replacing them all with new ones from "captainfantastic07" on eBay.

Interesting. We'll want to know how those work out. They certainly look nice on the outside but looks like the innerds (i.e. the working parts) are salvaged from old A-P pots. And I'm skeptical about his scary "never use L-pads" story. Ebay seller Vintage-AR has been selling L-pads as pot replacements for years and has never had a problem.

Good luck and keep us posted.

-Kent

[fran604g]

1 hour ago, JKent said:

Interesting. We'll want to know how those work out. They certainly look nice on the outside but looks like the innerds (i.e. the working parts) are salvaged from old A-P pots. And I'm skeptical about his scary "never use L-pads" story. Ebay seller Vintage-AR has been selling L-pads as pot replacements for years and has never had a problem.

Good luck and keep us posted.

-Kent

Thank you, Kent. I'll be sure to post my results. There doesn't seem to be much info on the innernut regarding these replacement pots, so it's bit of a gamble for me (and not a cheap one), but I just don't like the idea of using L-pads if I can do something more "historically correct". Once I open up the cabinets, I need to check the impedance of the tweet I earlier resoldered - the foam is crumbling pretty significantly at one location, so I'm thinking of sending it off to Chris. I think we can guess at what under the dome must look like after 50 years. 

I will keep these running for as long as I can, I'm still quite enamored with my 3a's! 

Fran

[JKent]

15 minutes ago, fran604g said:

so I'm thinking of sending it off to Chris.

From what I've heard, that's a good idea if you want "historically correct". Best bet is probably to send BOTH to Chris because I'm sure the rebuilt one will be quite different from the other half-century-old one. Just my 2 cents....

Kent

[fran604g]

2 minutes ago, JKent said:

From what I've heard, that's a good idea if you want "historically correct". Best bet is probably to send BOTH to Chris because I'm sure the rebuilt one will be quite different from the other half-century-old one. Just my 2 cents....

Kent

Point taken. It would probably be foolish for me to do otherwise. 

 

Fran

[ra.ra]

1 hour ago, fran604g said:

There doesn't seem to be much info on the innernut regarding these replacement pots...

I'm pretty sure they've been purchased and installed and blessed in this forum not long ago. Perhaps someone with experience will chime in.

[fran604g]

19 hours ago, ra.ra said:

I'm pretty sure they've been purchased and installed and blessed in this forum not long ago. Perhaps someone with experience will chime in.

I found a few posts here and at AK (iirc), but nothing definitive about their performance, and of course there's nothing long-term established yet.

I have to believe that if they're exact electrical duplicates of the originals, they must deliver the same results. It's worth noting I didn't find anything negative - no pun intended.

[ra.ra]

2 hours ago, fran604g said:

....but nothing definitive about their performance, and of course there's nothing long-term established yet.

Yeah, I think you're right - - - there has probably been very little feedback on performance thus far, and certainly nothing long-term. These pots appear to have a very robust build quality.......but yes, they are expen$ive.

[lARrybody]

On 3/14/2019 at 10:44 AM, ra.ra said:

These pots appear to have a very robust build quality.......but yes, they are expen$ive.

Not as expensive as the Ohmite RHS15RE potentometers, and they are self contained. No need for a enclosure. I see they are now $5.00 more than when I purchased them last year. 

[fran604g]

2 minutes ago, lARrybody said:

Not as expensive as the Ohmite RHS15RE potentometers, and they are self contained. No need for a enclosure. I see they are now $5.00 more than when I purchased them last year. 

How do you like them?

[lARrybody]

I used a set of four on some AR5's that had been redone 2 years ago with L-pads on the tweeters and Ohmites on the midranges. Like Ra.Ra. stated the build quality is fantastic. My testing with a ohmmeter  shows that the range is spot on and smooth. They are a little bit stiffer than the RHS15RE and don't  have the flat shaft end, but these differences turned out to be of no consequence . I wish I had opened one up and looked inside, but it is like  the old adage "if it's not broke".  I have a set of super nice early 3a's to do this summer and I am debating getting another set or using a set of Ohmites I have stashed away.  To me (my opinion) L-pads are not appropriate and rebuilt original Aetna-Pollak pots are just asking for future problems. 

I wish I knew where Captain Fantastic sourced these potentometers.  I will give them two thumbs up.