From: Paul Burridge
Subject: Re: Class B amplifiers: what are the large low-value resistors for?
X-Newsreader: Forte Agent 1.8/32.548
Date: Tue, 19 Nov 2002 09:15:05 +0000
NNTP-Posting-Date: Tue, 19 Nov 2002 10:43:51 GMT
Organization: Virgin Net Usenet Service
On 14 Nov 2002 17:14:24 -0800, email@example.com (N. Thornton) opined
>I'm thinking you're not using class B here :) More like AB, which is
>somewhat different. Class B would be simpler, and can in fact be made
>to work without any problematic level of crossover distortion.
It was *supposed* to be pure class B but for some reason it's
definitely well into the AB region. :-\
>If you're willing to use geranium output trs you can do a much simpler
>cct that's totally stable and sounds nice. I always do that for
>Use an LM324 opamp to drive 2 small 1 watt Ge output trs, no bias.
>Just connect the bases together and hook them straight to the LM324
>output. A few Rs for the opamp feedback, one output cap, and thats it!
>It only works with geraniums though: silicons give terrible crossover
>dist. And its runaway proof, despite the lack of any obvious runaway
Interesting. Yes, it hadn't occurred to me until you mentioned it that
the lower barrier height of germanium devices would better in respect
of the non-linearity of the crossover region.
"I was going to help him up, but then I thumped him."
Michael Head's plea in mitigation to Weybridge Magistrates, Sept. 1975