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AA Crossover refresh?


alzinski

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Hello Everyone, My name is Albert and I stumbled upon this wonderful forum looking for information on my crossover networks in my La Scala speakers. There is a lot of information on here, almost too much to go through. I wanted to say hello and introduce myself to all of you and maybe ask a few questions.

 

Here is my main question. What type of capacitor is in the stock AA speaker? They say Aerovox and to me they look like oil filled capacitors. Is the dielectric paper? Do these go bad with age? I measure them in regard to capacitance and they seem fine. There doesn't seem to be a consensus on what the best replacement type. Does anybody have any recources on the old capacitors? I specifically would like to know what ESR they would be originally and see how close these are to those numbers. If they have increased in ESR then I would like to find an replacement as close to the original as possible.

 

Thank you

 

Albert

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Hi djk,

 

What is the target ESR for the stock capacitors?  Some people tell me to put the highest quality caps in which would most likely be polypropylene but I would think they are so different from the original caps it will change the sound? I am assuming the original caps new would have a higher ESR compared to a modern polypropylene cap.  This is what led me to join here as this is a very specific question and other forums didn't know the answer. There must be a guru that was around when these caps came out and roughly knows the ESR.

 

I guess I should just start by measuring the stock caps ESR and go from there, but that won't tell me much unless I know what the value was back when they were new. They sound great to me, I am just curious if they could be better to these old ears.

 

Thank you.

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Lowest ESR is not the path to best sound. Bright, thin, and an ear piercing presentation that is more painful than anything else. 

 

Use Jensen paper in oil or Jupiter wax paper and foil for best results. This will get you closest to the original stock sound. 

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FWIW I like the inexpensive Russian MBGO caps  (see E-bay listings from Bulgaria) - have them battery biased in one AA-type,   WIMA DC-Link might be good value - low ESR- might sound harsh with some amps (?) They come in 10uF and 2uF and reasonable price at Mouser.  Drlowmu says use the 4-lead variety and apparently mixes other type for "voicing".   My cheap ESR meter (which should give more consistent and accurate readings with 2mm-4mm adapters and better leads) reads some "Vloss" for the paper dielectric caps, but usually reasonable ESR despite decades old/.  Those red-cheap Chinese "Audiophiler" caps seem to have very low ESR.

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Deang seems to be in the camp of low esr is not a good replacement, I tend to agree. I looked up the capacitors referenced, wow! I have to be honest I will not spend >$100 per cap. I can't even find any technical literature on them.

 

Russian Surplus PIO is a good option that I am willing to try. Battery bias? Anyone care to explain why changing where the zero crossing will help. I read some tests on this years ago after hearing JBL uses batteries in their crossovers.  I can see maybe with an aluminum electrolytic cap, the DC will keep it 'formed'.

 

I am on the road traveling so I will measure the ESR of the stock caps as soon as time permits.

 

Thank you all for your responses.

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you can get a 10uF MBGO for less than $2 sans shipping and similar price for 2uF..  I first saw/heard  MBGO in some Baltek 90 decades ago.   Great sounding caps.  I have KBG 2uF in my Heresy pair and those are sweet but with foil plates, more expensive.   

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  • 1 month later...

" I thought the whole reason you changed them was due to age. "

 

The Russian caps are hermetically sealed, the oil caps used by Klipsch after the early '70s were not. Lead failure due to ESR on non-hermetic caps is the issue, age, per se, is not.

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I don't know if Bob Crites still has the oil caps like I got from him years ago. But why not just use his preference and be done with it . I have never seen as Bob also says the original test out to the right cap values.

Also a few have said we should use klipsch only products in our speakers . So call them up and ask how much to rebuild your 36 year old crossovers.....

  I would just call Bob up and tell him what you want to do or have him do it for you. He is a very good person to deal with and has helped many here including me.

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It would be something different to try and not really out a lot of money. The (4) 2uf caps are easy enough but they won't have a 13uf for mids. Guess I could get 2 more 2uf's, (2) 10uf's and maybe a pair of 1uf's and tinker with their values once tied together. Not much money. Can always go back to my Solen caps with minimal effort. I'm open to trying new things for the low cost of admission.

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3 hours ago, ricktate said:

I don't know if Bob Crites still has the oil caps like I got from him years ago. But why not just use his preference and be done with it.

 

Because 1) the GE motor runs that he liked and measured to his desired standard are no longer available, and 2) there are other capacitors that sound subjectively better.

 

 

Quote

... Bob also says the original test out to the right cap values.

 

Not really true. Capacitance might be close, but the ESR typically measures very bad. When a capacitor measures more like a resistor than a capacitor - it's time for the trash can. 

 

 

Quote

A few have said we should use Klipsch only products in our speakers. So call them up and ask how much to rebuild your 36 year old crossovers...

 

Yeah, good luck with that. 

 

 

Quote

I would just call Bob up and tell him what you want to do or have him do it for you. He is a very good person to deal with and has helped many here including me.

 

+1 ... but ... I just read your PM. 

 

I would convert them to Type A networks. All you would need is two 12s and two 2s or 2.2s. 12uF is perfectly fine. PM me your budget, and I'll step you through this. 

 

People. Don't forget - if you're strapped for cash - please pursue battery biased (charge coupled) crossovers. You can use Daytons or Bennics and they sound great. 

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