another question--2n4250/electrolytic caps

[Patric D'Eimon]

Another question about the same preamps. There is 47mfd/10v cap just before
the 2n4250 and a 4.7mfd/25v electrolytic cap just after the transistor both
of them in the signal path. Can I replace these with higher quality
components? Polypropolene, mylar, ceramic? Thanks for your help. Patric

[Peter Larsen]

Patric D'Eimon wrote:
>
> Another question about the same preamps. There is 47mfd/10v cap just before
> the 2n4250 and a 4.7mfd/25v electrolytic cap just after the transistor both
> of them in the signal path. Can I replace these with higher quality
> components? Polypropolene, mylar, ceramic? Thanks for your help. Patric

Replacement is hardly relevant if they are OK and if there is a dc
voltage across them larger than the signal peak to peak voltage, adding
a small bypass something may or may not be. Electrolytic coupling caps
are a potential worry if they do *not* have a suitable voltage drop in
the proper direction to keep them biased, that is the problem with split
supply designs. The cheapest remedy is to use two caps in series and
apply an offset-voltage to the midpoint.


Kind regards

Peter Larsen

--
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* My site is at: http://www.muyiovatki.dk *
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[Justin Ulysses Morse]

Patric D'Eimon > wrote:

> Another question about the same preamps. There is 47mfd/10v cap just before
> the 2n4250 and a 4.7mfd/25v electrolytic cap just after the transistor both
> of them in the signal path. Can I replace these with higher quality
> components? Polypropolene, mylar, ceramic? Thanks for your help. Patric


I have some 47mfd film capacitors here, and they're about the size of a
D-cell battery. Odds of one fitting onto your circuitboard in the
space available seem slim. a 4.7mfd cap will be smaller, but still
probably larger than the space available. If the circuit is very old,
you might benefit from replacing these caps with new electrolytic caps
because you can get more capacitance into a smaller space than you used
to, and the quality will be higher.

ulysses

[Stephen Sank]

If those lytic caps are original, they are certainly too old to be anywhere near their intended
performance. I'd suggest replacement with low-esr Nichicon lytics, and, for maximum sonic
performance, parallel as large a polystyrene or polypropylene film cap as will physically fit
the space.
Oh, and I concur on the 2SA970 recommendation, with the heavier version 2SA965 an excellent
choice as well.

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"Patric D'Eimon" > wrote in message ...
> Another question about the same preamps. There is 47mfd/10v cap just before
> the 2n4250 and a 4.7mfd/25v electrolytic cap just after the transistor both
> of them in the signal path. Can I replace these with higher quality
> components? Polypropolene, mylar, ceramic? Thanks for your help. Patric
>

[Patric D'Eimon]

with unquestioned accuracy of thought, Justin Ulysses Morse replied:

> Patric D'Eimon > wrote:
>
>> Another question about the same preamps. There is 47mfd/10v cap just before
>> the 2n4250 and a 4.7mfd/25v electrolytic cap just after the transistor both
>> of them in the signal path. Can I replace these with higher quality
>> components? Polypropolene, mylar, ceramic? Thanks for your help. Patric
>
>
> I have some 47mfd film capacitors here, and they're about the size of a
> D-cell battery. Odds of one fitting onto your circuitboard in the
> space available seem slim. a 4.7mfd cap will be smaller, but still
> probably larger than the space available. If the circuit is very old,
> you might benefit from replacing these caps with new electrolytic caps
> because you can get more capacitance into a smaller space than you used
> to, and the quality will be higher.
>
> ulysses
Thanks, Patric