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

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.

That is odd. The protection was - particularly in earlier models - too
severe. However it really *should* protect the output devices. Were some
small signal devices earlier in the amp also damaged? If so, it may be that
this lead to a failure that the protection system isn't designed to deal
with.

Slainte,

Jim

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