On 14 Jun 2004 18:09:01 GMT, ohawker (Andy
Evans) wrote:

Are you telling me that your designs are so incompetent that (blah blah).

I repeat exactly what I said before. Give me a selection of valve circuits that
you have personally designed, with detailed construction notes showing that
changing componants had no effect on he sound.

See below:
What I propose is that you give me a selection of your own valve amplifier
circuit designs with your detailed construction notes which prove that
substituting componants has no effect on the sound. In return I will give you a
selection of my own valve amplifier circuit designs with my detailed
construction notes on the diverse effects of substituting componants. You are
welcome to breadboard my circuits with the relevant parts to check whether your
own ears confirm the effects I have found. That sounds reasonable doesn't it?
Let's put this to the test.







=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

My valve design - years ago now - was concerned with a discipline
vastly more demanding than audio; measurement. I designed equipment
for measuring labs, including the National Physical Laboratory. I can
assure you that although I selected components, the parameters were
all to do with reliability and stability; I never found any that would
alter performance by their substitution. That was because I designed
circuits properly, making sure that stability and performance did not
hang on some unpredictable parameter in a component. It isn;t the
easiest way to do it, but it is the right way. If you are seriously
suggesting that your amplifiers perform differently with carbon
resistors than with metal ones, despite the values being the same,
then you are doing something wrong.

Probably Jim has it right when he suggests the problem may be marginal
stability which is causing the amplifier to oscillate with the changed
parasitics of one component type. That would be a logical assumption
based on your evidence. But all that points to is incompetence of
design, not some mystical property of components (hint - they don't
have any!).

d
Pearce Consulting
http://www.pearce.uk.com