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Acoustic Research ar5 rebuild questions/opinions


BigRiver

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Hi,

I just picked up a set of ar5's in decent shape for what I would consider an o.k price, not great and not too bad. I have three days to decide if I want to keep them, and they are going to need work, I just am not sure if this set is worth the expense.

One speaker works pretty well as in sounds is coming from all three drivers, the other side as very soft/muted sound coming from the high and mid. From initial research I assume this is a pot issue ( and that I should do the soak/clean/etc. that I have seen.  The other option I am seeing are to buy newly manufactured ones on that auction site made specifically for the ar's - but it's $120 for all 4 of them.  

It seems likely that these needs a recap since I have read that they can be pretty excellent, right now they just sound like cr@p.  I am having a bit of a hard time finding the 4uF - 24uF - and 72uF all in one place.  Found the 72uF at mouser but again $$$$ and the same with the 4uF from parts Xpress.

Does anyone have experience with these, have any advice or things to specifically look for, ideas on better pricing on the caps, etc?

Thanks,

Dan

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  • BigRiver changed the title to Acoustic Research ar5 rebuild questions/opinions

Hi Big River and welcome

Congrats on the AR-5s. They're great speakers. Be sure to download the AR-3a restoration guide--there are many similarities. http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

Those pots on ebay are apparently fine but, as you said, pricey. Use L-pads from Parts Express. PE will also have the caps. Mouser is a great source for all things electronic but not so good for speaker caps. For speakers the caps must be non-polarized. All film caps are but for electrolytics you have to specifically get NPE speaker caps. I'll take a look at PE and get back to you.

Kent

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Here are the L-pads. https://www.parts-express.com/speaker-l-pad-attenuator-15w-mono-3-8-shaft-8-ohm--260-248 Just be sure to ask us about the wiring if you go this route.

And while you're ordering from PE get some of this  https://www.parts-express.com/parts-express-speaker-gasketing-tape-1-8-x-3-8-x-50-ft-roll--260-540

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19 minutes ago, JKent said:

Here are the L-pads. https://www.parts-express.com/speaker-l-pad-attenuator-15w-mono-3-8-shaft-8-ohm--260-248 Just be sure to ask us about the wiring if you go this route.

And while you're ordering from PE get some of this  https://www.parts-express.com/parts-express-speaker-gasketing-tape-1-8-x-3-8-x-50-ft-roll--260-540

Wow JKent above and beyond!  Thank you so much for these recommendations, though I might just spring for the pots, haven't totally made up my mind on those.  

The 72uF's will save me a small stack alone as I was looking at these:  https://www.mouser.com/ProductDetail/505-DCP5-72-1100-10/

 

So I gather from the above that it is O.K. to use caps that are as close as possible to the original values but not necessarily exactly matching if it is difficult to match.

 

 

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Glad to help. As I said, Mouser is a very good source but not for speaker capacitors. Those 72uF WIMA caps from Mouser are expensive and huge. NPEs from PE will work fine for 2 or 3 or 4 decades.

I created a little firestorm in another thread by being too flippant about capacitor values. But yes--you can caps that are close. Most modern caps are almost spot on, even when rated +/- 5%. So it's fine to use a cap that's 5% or even a little more off the desired value. For your speakers, 25uF is a perfectly good substitute for 24uF. 75uF is fine for 72. I just rebuilt a crossover using 3.9uF for 4uF and 15uF for 16uF. No need to get all OCD about differences of 5% or less.

The pots are your call. They seem pretty solid and they are sealed (unlike the Ohmite pots I used in my 3a's) but I'll just say that virtually all the people on this forum have been won over by cheap L-pads. AR used L-pads in later versions of the AR-3a.

And there is a small chance that the issues with your speakers may be with the actual tweeters and mids, in which case you'll want to save some money to have Roy or Chris do rebuilds.

Kent

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6 minutes ago, JKent said:

Glad to help. As I said, Mouser is a very good source but not for speaker capacitors. Those 72uF WIMA caps from Mouser are expensive and huge. NPEs from PE will work fine for 2 or 3 or 4 decades.

I created a little firestorm in another thread by being too flippant about capacitor values. But yes--you can caps that are close. Most modern caps are almost spot on, even when rated +/- 5%. So it's fine to use a cap that's 5% or even a little more off the desired value. For your speakers, 25uF is a perfectly good substitute for 24uF. 75uF is fine for 72. I just rebuilt a crossover using 3.9uF for 4uF and 15uF for 16uF. No need to get all OCD about differences of 5% or less.

The pots are your call. They seem pretty solid and they are sealed (unlike the Ohmite pots I used in my 3a's) but I'll just say that virtually all the people on this forum have been won over by cheap L-pads. AR used L-pads in later versions of the AR-3a.

And there is a small chance that the issues with your speakers may be with the actual tweeters and mids, in which case you'll want to save some money to have Roy or Chris do rebuilds.

Kent

Ahh, that's a good point.  I have removed the tweeters and mids from the first and they are right around 6.5 ohms, though the mid jumped around a bit before settling at 6.3, which made me nervous, though now it seems to be a pretty solid reading.  Seeing that so many have used the L-pads, and given the cost difference, that just may be the way to go.

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HI guys. I recently picked up a set of AR5s in Hong Kong. I need to order caps for both speakers and have a guy who will help me replace them.  I found this thread which is great as I am a novice.  The caps above seem different from the ones in the AR3a guide. Did the AR5 have a different crossover?  If not too much trouble could you let me know exactly what to order (I have replacement pots already)? Keen to have these done right and keep them for another 50 years (hopefully I will live that long!).  Thank you in advance for any help

Would this work:

My desired outcome is to order the capacitors and gasking material for a local guy to help me do the work. Any thoughts on a specific shopping list would be very helpful as I am a total novice but love these speakers.  Really appreciate the help. Is this the correct order of parts:

https://www.parts-express.com/Dayton-Audio-DMPC-75-75uF-250V-Polypropylene-Capacitor-027-445?quantity=1  (x4)

https://www.parts-express.com/Dayton-Audio-DMPC-50-50uF-250V-Polypropylene-Capacitor-027-443?quantity=1 (x2)

https://www.parts-express.com/Dayton-Audio-DMPC-6.2-6.2uF-250V-Polypropylene-Capacitor-027-427?quantity=1 (x2)

https://www.parts-express.com/Speaker-Gasketing-Tape-1-8-x-3-8-x-50-ft.-Roll-260-540?quantity=1

Edited by Ecjenkins
added more info
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Does this order make sense for my AR5 restoration if you dont mind to help? The desired outcome is to order the capacitors and gasking material for a local guy to help me do the work. Any thoughts on a specific shopping list would be very helpful as I am a total novice but love these speakers.  Really appreciate the help. Is this the correct order of parts:

https://www.parts-express.com/Dayton-Audio-DMPC-75-75uF-250V-Polypropylene-Capacitor-027-445?quantity=1  (x4)

https://www.parts-express.com/Dayton-Audio-DMPC-50-50uF-250V-Polypropylene-Capacitor-027-443?quantity=1 (x2)

https://www.parts-express.com/Dayton-Audio-DMPC-6.2-6.2uF-250V-Polypropylene-Capacitor-027-427?quantity=1 (x2)

https://www.parts-express.com/Speaker-Gasketing-Tape-1-8-x-3-8-x-50-ft.-Roll-260-540?quantity=1

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2 hours ago, Ecjenkins said:

Does this order make sense for my AR5 restoration if you dont mind to help?

No.  Use this Jkent list from above in this thread.  You need a 4 a 24 and a 72 per cabinet.  You are unlikely to find those exact numbers unless you have original caps in your speakers.  If the original caps are Sprague Compulytic consider keeping,  if not Sprague then replace using the guidelines from Jkent below.image.png.0424bc3840561866a7f78d299a7cb7cc.png

 

On 1/9/2021 at 2:10 PM, JKent said:

Here are the L-pads. https://www.parts-express.com/speaker-l-pad-attenuator-15w-mono-3-8-shaft-8-ohm--260-248 Just be sure to ask us about the wiring if you go this route.

And while you're ordering from PE get some of this  https://www.parts-express.com/parts-express-speaker-gasketing-tape-1-8-x-3-8-x-50-ft-roll--260-540

 

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