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?
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?
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.
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.
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.
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.
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.
What impedance do the caps see? Do you really need 10uF? measure the -3db point at each stage that uses coupling caps and see if you can get smaller values to do the job (I bet you can). You may find that even a single 1 or 2uF cap still gives you a -3db point below 10Hz.
As far as whether it is audible or not, I would replace them. Having lived through the capacitor revolution in the late 70's, I have never trusted a polorized cap since.
As far as whether it is audible or not, I would replace them. Having lived through the capacitor revolution in the late 70's, I have never trusted a polorized cap since.
Hi Bill,
I echo the suggestion to // back to back electro with a film cap. eg.22uF+22uF//1uF film. 25v to 50v should be ok and still not too big. I have used poly carbonate to good effect & the uncased stacked film are very small. Oh, btw check the frequency that a 1uF manages say 100Hz @-3db then effectively the film covers the range 200Hz to 20kHz and higher and the electro only fills in the bass.
I echo the suggestion to // back to back electro with a film cap. eg.22uF+22uF//1uF film. 25v to 50v should be ok and still not too big. I have used poly carbonate to good effect & the uncased stacked film are very small. Oh, btw check the frequency that a 1uF manages say 100Hz @-3db then effectively the film covers the range 200Hz to 20kHz and higher and the electro only fills in the bass.
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