On Fri, 21 Nov 2003 08:55:19 +0000 (GMT)
Jim Lesurf wrote:

Not clear what you are describing above. Are you saying that the *Quad
405* blew its output devices due to your injecting an input spike when
your'preamp' sic was switched on? Or are you saying the preamp
output devoices blew?

the 405.

Anyhow, this is the event that made me decide to mod the amp. the
current limiting on the 405 was too severe, which is what allowed
the o/p trannies to blow (before the fuses could save them).

Puzzled. The point of the current limiting is to ensure the output
devices*never* blow up. The severe limiting on early 405's gets in the
way of the music sometimes, but should avoid failures. Hence I am
puzzled by your last sentence above.

It appears to limit current just enough to prevent the fuses blowing but
not quite enough to save the transistors.

Im modding the amp (rebuilding the PCBs) such that:

Have you checked the stability margin? Reducing the overall gain and
changing various devices to different types may affect this.

No, not yet. I havent really had time for the project lately...

Jim... did you ever look at the schematic I sent you ?

I am afraid I haven't. :-/ Too many other things have been
distracting me over the summer - many of them unfortunate. Sorry about
this, but I had completely forgotten. Can you remind me of the details
by email?

Sure.

--
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Do not meddle in the affairs of Dragons, for you are tasty and good with
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