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Old 1st March 2005, 06:34 PM   #1
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Default Pre-amp coupling caps

I've gotten this bee in my bonnet that replacing the 1ufd and 10ufd electrolytic coupling caps in a Nikko Beta 20 pre-amp will make it sound better.

The pre-amp is only 1RU and the board is rather crowded. I'd like to use film caps but unless I can find some miniature 50v axial units I guess I'm stuck with Black Gate NP electrolytics from Percy Audio.

Anybody know of a source for mini film units?

And, most importantly, is this going to be worth the trouble?
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Old 1st March 2005, 07:10 PM   #2
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How about tantalum caps, they can be pretty small relative to alu electros.
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Old 1st March 2005, 07:27 PM   #3
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Quote:
Originally posted by richie00boy
How about tantalum caps, they can be pretty small relative to alu electros.
All I have heard about tants has suggested to me that they would make lousy coupling caps, sounding worse than any other cap.

Although I did do a passive crossover with back to back tants about 30 years ago and they sounded alright to me.
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Old 1st March 2005, 07:43 PM   #4
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Try it and see? Or just leave the existing caps in and parallel them with nice caps of 1% of the big caps value.
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Old 2nd March 2005, 12:38 AM   #5
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Can I have some more input here, pleeeeze.

How come when I post a question everybody logs off?
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Old 2nd March 2005, 01:24 AM   #6
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Bill, what is the worst-case impedance of those awful electrolytics at audio frequencies? What's their load? What does the voltage divider equation say about their effect? (Tip o' the hat to Jim Bongiorno)

Now it's possible they've deteriorated over the years in which case some nice, new premium-grade Al electrolytics will sound fine in that circuit.
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Old 2nd March 2005, 02:43 AM   #7
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I wasn't think about their effects on response but about distortion.

Has there been any difinitive conclusion on this matter?
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Old 2nd March 2005, 02:59 AM   #8
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Well, think about it- from a theoretical point of view, the impedance of the cap can be 100% nonlinear, but if that impedance is 1/100,000th of the load, what's the source of distortion?

From a practical point of view, how many amps have electrolytic coupling caps outside the feedback loop yet show miniscule distortion? Plenty, and the Adcom 555 playing in my room at the moment is one of them.
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Old 2nd March 2005, 05:17 AM   #9
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Quote:
Originally posted by SY
Well, think about it- from a theoretical point of view, the impedance of the cap can be 100% nonlinear, but if that impedance is 1/100,000th of the load, what's the source of distortion?
Not to mention there's hardly any current through it to really work the dielectric. Now, motor start caps for example, those have some rough times.

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Old 2nd March 2005, 05:39 AM   #10
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Quote:
And, most importantly, is this going to be worth the trouble?

Bill

Only your ears can answer this question. Many like the BG-N and if they sounded good they would really be better than sliced bread - small, cheap, available. Sadly, they don't quite cut it for me.

You may find some polyprops meant for speaker crossovers to be relatively small (low voltage) but mounting won't be trivial.

How good is the Nikko? I suspect that the BG would be plenty good for it.
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