AR-3a Recap

[vinylviola]

Could anyone point the way to a thread on a 3a recap? Search here on AK won't allow a search with any sort of combination of "AR-3, 3a" etc. so I'm having trouble locating the cap values and recommended parts. Would the AK favs Dayton/Jantzen work fine in these speakers?

Thanks in advance...

 

[winters860]

Cap values: 150, 50, and 6uF. Daytons or Jantzens will be fine.

Full schematics and a lot of other good resources are available here:

The Classic Speaker Pages' Restoring The AR-3a

FWIW, the CSP brain trust recommends using a small resistor in series with modern poly caps to mimic the higher ESR of the original capacitors. Even I think that's a little anal.

 

[vinylviola]

Is there any voltage rating to consider with the caps?

 

[winters860]

My memory fails me in whether the original caps were rated for 50V or 100V, but anything exceeding 100V will be fine.

 

[vinylviola]

Thankyakindly....

 

[vinylviola]

Would a total of 2 or more of these 100 + 50 uf work in tandem?

Also, would it be recommended to mix the one available 1% cap (6 uf) with the 5% ones?

 

[vinylviola]

Sorry, here's the link:

http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-447

 

[winters860]

No problem with mixing 1% and 5% - the original caps had a 10% tolerance anyway. No problem using a 100 and a 50uf (or a 75 and a 75 for that matter) in parallel to get 150uF.

 

[vinylviola]

Wow, these are a bit more expensive than I thought! Initial cost (without S&H) is over $100!

 

[winters860]

Yep - if you're trying to cheap up, you could use non-polar electrolytics for the 150uf woofer caps,

 

[Urizen]

Yep - if you're trying to cheap up, you could use non-polar electrolytics for the 150uf woofer caps,

Expensive film caps on the bass sections of crossovers are a waste of money, IMO.

Good advice!:thmbsp:

 

[Zilch]

There IS a rationale.

At least bypass them, Theta 0.01 uF.

 

[MikeCh]

There IS a rationale.

At least bypass them, Theta 0.01 uF.

Zilch, are you saying that it's common to bypass the low frequency woofer capacitors with the Theta 0.01 uF if NPE's are being used for that portion of the crossover? I usually hear of people using bypass caps in the high frequency portion of crossover networks, so is it done in the low frequency sections too?