How much of a capacitor upgrade do AR-3a's need?

[jonwb]

Hi... I have a pair of 1969 AR-3a's given to me by a friend. I've restored the cabinets, cleaned the original potentiometers and have had the tweeters restored. They're now beautiful and playable. Honestly, I don't know too much about AR's history but I know these were considered good speakers back in the day, and they'll probably become my last living room speaker using my Adcom or Denon amps.

I'd like to upgrade the original electrolytic capacitors. (6uf & 50uf film, and a 150uf non-polar electrolytic). I'm good with the wiring layout but I just don't know what brand to buy. The Reddit groups seem to swear by Dayton for quality & cost, but I feel these might deserve something a little better. Your thoughts?

 

[TurtlePaul]

It doesn’t matter. Any poly film caps like the Daytons will be fine. There is no audible difference. The reason to upgrade old electrolytic caps is because their capacitance value drops as they age. People have measured the frequency response and distortion of various non-electrolytic caps and an audible difference is just not there.

 

[MAB]

Hi... I have a pair of 1969 AR-3a's given to me by a friend. I've restored the cabinets, cleaned the original potentiometers and have had the tweeters restored. They're now beautiful and playable. Honestly, I don't know too much about AR's history but I know these were considered good speakers back in the day, and they'll probably become my last living room speaker using my Adcom or Denon amps.

I'd like to upgrade the original electrolytic capacitors. (6uf & 50uf film, and a 150uf non-polar electrolytic). I'm good with the wiring layout but I just don't know what brand to buy. The Reddit groups seem to swear by Dayton for quality & cost, but I feel these might deserve something a little better. Your thoughts?

The Dayton will be great. They will perform as any other reasonable metal film speaker capacitor. Hovland, Solen, Auricap, Jantzen, etc.

The replacements will likely have different series resistance than the originals, which may or may not be audibly different if a comparison were to be made.
For the 150 uF, three 50uF in parallel will be equivalent if reasonably priced 150uF caps aren't available.
Good luck!

 

[jonwb]

Sorry for the late reply. Went in for emergency surgery and just got back from rehab...

I appreciate the information. I've done a bit more research. I can get Dayton 50uf and 150uf polys pretty inexpensively at PE. However, some would suggest that getting an updated 6uf capacitor for the high end is best? Maybe a ClarityCap or Mundorf? Would anyone agree?

 

[SIY]

Maybe a ClarityCap or Mundorf? Would anyone agree?

They'll work, but I'd be more inclined to use something more industrial like Wima, Vishay, Panasonic...

 

[a4eaudio]

My budget capacitors or usually Dayton and Audyn Q4. Check out Jule Fidelity / JF Components for some really nice budget stuff - a company started last year or so by a former DIYer.

My "high end" capacitors are Clarity Cap and Jantzen Standard-Z which are not very "high end" for those who like to spend a lot of money on capacitors.

 

[SIY]

My budget capacitors or usually Dayton and Audyn Q4. Check out Jule Fidelity / JF Components for some really nice budget stuff - a company started last year or so by a former DIYer.

My "high end" capacitors are Clarity Cap and Jantzen Standard-Z which are not very "high end" for those who like to spend a lot of money on capacitors.

An industrial-grade cap (like the kind you buy at DigiKey or Mouser or Newark) will be more likely to have tighter winding and higher reliability than limited production stuff made manually or on small machines. And avoid PTFE/Teflon at all costs!

 

[jonwb]

My "high end" capacitors are Clarity Cap and Jantzen Standard-Z which are not very "high end" for those who like to spend a lot of money on capacitors.

Yeah, chose the wrong wording there

 

[jonwb]

Madisound sells a ClarityCap PX 6uf 250v cap... https://www.madisoundspeakerstore.com/px-cap-250vdc/claritycap-6.0-mfd-px-range-polypropylene-caps/

This would be a drop-in for the AR-3a 6uf hi-range capacitor. I'm wondering if anyone has used this as an option?

 

[MAB]

Sorry for the late reply. Went in for emergency surgery and just got back from rehab...

Welcome back. Hope you are getting well.

I appreciate the information. I've done a bit more research. I can get Dayton 50uf and 150uf polys pretty inexpensively at PE. However, some would suggest that getting an updated 6uf capacitor for the high end is best? Maybe a ClarityCap or Mundorf? Would anyone agree?

If the Dayton are easy to source, get them. I have a large collection of their caps, they are fine.
I would avoid the Mundorf and ClarityCap. They are not best for tweeter filters or anything else.

The best upgrade you could get is a DATS from Dayton. It will allow you to actually measure the caps in your speakers, see if they have actually gone bad or drifted out of spec, and if you even need to replace them. Also will help you debunk the supposed superiority of fancy-caps.

 

[a4eaudio]

I am not a promoter of more expensive caps. IF I upgraded my caps on a tweeter, the most expensive I would go is likely the Clarity Cap below. But I wouldn't normally buy that.

ClarityCap 6.2 mfd CSA CopperConnect Poly Cap 250V

ClarityCap 6.2 mfd CSA CopperConnect Poly Cap 250V

www.madisoundspeakerstore.com

 

[SIY]

Industrial quality caps in those values are about 10-15% of that price and likely of far better quality.

"Audiophile" is a sucker's game.

 

[jonwb]

Welcome back. Hope you are getting well.

Hey thanks... fun getting older

If the Dayton are easy to source, get them. I have a large collection of their caps, they are fine.
I would avoid the Mundorf and ClarityCap. They are not best for tweeter filters or anything else.

The best upgrade you could get is a DATS from Dayton. It will allow you to actually measure the caps in your speakers, see if they have actually gone bad or drifted out of spec, and if you even need to replace them. Also will help you debunk the supposed superiority of fancy-caps.

Ok, well honestly the DATS unit is a bit costly right now. Keep in mind these are 55 yr-old speakers. If I cut the wires and the uf specs are wildly off, can I assume the ESR will be inflated too?

 

[jonwb]

Industrial quality caps in those values are about 10-15% of that price and likely of far better quality.

"Audiophile" is a sucker's game.

Thanks SIY... are you a proponent of polypropylene film capacitors or would you just stick with NPE caps? I have no problem using Panasonic, Vishay or Nichicon as long as I can find the correct uf specs and they're in stock.

 

[MAB]

Hey thanks... fun getting older

Ok, well honestly the DATS unit is a bit costly right now. Keep in mind these are 55 yr-old speakers. If I cut the wires and the uf specs are wildly off, can I assume the ESR will be inflated too?

Yes. Understand the expense isn’t necessary for you to move forward.
No harm in replacing the caps outright with new. May not make one iota of difference. But hard to actually mess up most passive crossover filters. Common mistake is to swap out an iron core inductor with an air core fancy inductor in a notch filter application: these notches are sensitive to the resistance change! Just one example, probably doesn’t apply to your project.

 

[Bruce Morgen]

If you're already planning to replace those old caps and aren't concerned with "vintage" authenticity, you might want to consider making a substantive change to the crossover circuit, e.g. something like what's discussed this DIYaudio thread: AR3a "improved" - It works!

 

[SIY]

Thanks SIY... are you a proponent of polypropylene film capacitors or would you just stick with NPE caps? I have no problem using Panasonic, Vishay or Nichicon as long as I can find the correct uf specs and they're in stock.

I would use the type that were part of the original design. I've had experiences where changing to a film cap made no discernable difference and experience where the sound was negatively affected. For a new design, I use electrolytics for places where large values are required and the ESR is not important (e.g., a Zobel across a woofer), polypropylene film everywhere else.

Fortunately, modern electrolytics have much better lifetimes than the vintage ones.

 

[Bruce Morgen]

Fortunately, modern electrolytics have much better lifetimes that the vintage ones.

Especially in passive speaker applications, where they're not exposed to anything in the way of heat or significant voltage spikes.

 

[restorer-john]

I understand you've likely spent considerable time and effort already restoring the cabinets (they look great) and you want to do the same for the crossovers. Take note of SIY's comments, they are right on the money.

 

[jonwb]

I would use the type that were part of the original design. I've had experiences where changing to a film cap made no discernable difference and experience where the sound was negatively affected. For a new design, I use electrolytics for places where large values are required and the ESR is not important (e.g., a Zobel across a woofer), polypropylene film everywhere else.

Fortunately, modern electrolytics have much better lifetimes than the vintage ones.

Ok thanks... So what I'm hearing is that you'd suggest non-polar electrolytics for the 50uf and 150uf caps, and a film cap for the 6uf tweeter?