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Cap ESR? Or just measure dB loss at speaker terminal?


efzauner

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Lots of recommendations to replace 20 year old crossover caps because of both drifting capacitance and increased ESR.   I can measure capacitance easily. ESR is more difficult.  

 

It is easy to measure the frequency response of the HP or Mid band pass section.  If I measure no loss or a fraction of a dB would this not indicate a low ESR?  

 

A 0.1 ohm ESR in series with an 8 ohm driver is only 0.1dB down.  Seems trivial to worry about?  

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" Seems trivial to worry about?   "

 

If you read the comments from the knowledgeable here (BEC, others), they point to an ESR of 0.5 as becoming audible.

 

As a voltage divider 0.5Ω in series with a 6Ω tweeter is about -0.3476dB

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I still don't quite understand why someone would not replace old capacitors, when new (very good) capacitors are so inexpensive and easy to replace?  I mean sure, you can spend bundles on some caps, but Dayton 1% Precision Audio Caps are terrific for the money....(and I'm not saying those are the only ones....)  Why wait for the old caps to degrade and fail?

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The old capacitors will eventually start leaking all over the board -- just bad news all the way around.

 

The later axial mylars sound horrible -- they should also be replaced (regardless of how they measure).

 

Using metalized polypropylenes will require knocking a little off of the midrange output (since the original capacitors were somewhat lossy).

 

The Dayton capacitors are a good value, but there are better options (right Jim).

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http://jupitercondenser.com/product/vt-round-aluminum-foil-wax-and-paper-capacitors/

 

http://jensencapacitors.com/products/speaker-capacitors/aluminium-foil---paper-in-oil---tinned-copper-leadout.aspx

 

https://www.v-cap.com/oil-capacitors.php

 

Some will tell you to not waste your money.  I'll tell you that it was not a waste of mine.  Depending on the setup, money might be better spent elsewhere first.

 

 

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10 minutes ago, muel said:

The Russian caps were great in the NBS preamp but it would have been hard to not hear the the difference between them and the Duelunds.  That said, if I were to do it again I would have gone with Jupiter.  Sorry that I digress... the OP was about speaker capacitors.   

33425252101_0730131368_k.jpg

 

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On 10/30/2017 at 7:02 PM, Deang said:

The old capacitors will eventually start leaking all over the board -- just bad news all the way around.

 

The later axial mylars sound horrible -- they should also be replaced (regardless of how they measure).

 

Using metalized polypropylenes will require knocking a little off of the midrange output (since the original capacitors were somewhat lossy).

 

The Dayton capacitors are a good value, but there are better options (right Jim).

I can understand electrolytics failing and leaking. But the KLFs have metal film in mid and high sections. What is the lifetime of these?  

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" What is the lifetime of these?   "

 

Indeterminate.

 

The leads on inexpensive film caps are just just smashed into the ends of the caps after coated with a tin paste.

 

Better caps have soldered leads, and they last longer.

 

The old oil-filled caps also fail over lead termination issues.

 

50 years ago, JBL used stacked-film caps with hand soldered teflon insulated copper wire leads, wax potted in sand-filled paper tubes. I have never seen one of those that has failed.

 

$_35.JPG

 

3112backgz4.jpg

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