Re: Recommended capacitors for AF circuits

Ken Smith wrote:
In article <1145594802.304726.258110@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Glenn Gundlach <stratus46@xxxxxxxxx> wrote:
[....]

So a question comes up. If capacitors are bad, what is the minimum
number you can get away with in the signal path by direct coupling and
balanced supplies ?


The obvious answer is zero. This assumes that you can trim away the offset and it will stay trimmed away.
[...]

Is there a way to servo the audio to prevent offsets from 'stacking
up'?


Capacitors are not the only way to integrate.

In a lot of ways, inductors are worse than capacitors.

You could use an electric motor turning a pot but this is mechanically
big.

Electrochemical methods could be used but I suspect that they are worse than capacitors in nearly every way.

You could use a microcontroller and a 24 bit DAC. This actually sounds almost practical.


Or would that then get to the 'opamps are bad' too ?


A lot of op-amps are bad.



This application uses two LM1036s capacitively coupled to four LM386s. The speakers are WEATHERPROOF type, rated 25W each (they were the only ones I could find for the operating environment (camper); 1W per speaker is overkill here).

The goal was and is for minimal parts count, hence my choice of ICs. For my purposes hi-fi is not a requirement, as long as the sound is good, no hum, buzz, etc. Accurate reproduction is also not a must-have.

(Yeah, I know...I could buy a four-channel amp somewhere, but what's the point of an electronics hobby if I'm not going to build anything???)

Thomas

--

A thoughtful pause, then resumes the prince, "We must Learn from Yesterday, Live for Today, and look Forward to Tomorrow, for The Past be The Present, and No Less The Future."

.

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