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Krell amps and Tube Preamps - enemies?

Wow! I never realized how difficult it would be to add tubes with a KRELL amp. I'm no engineer, and, I don't pretend to be into the "technical" side of the audio world. So I'll try to explain.

It seems that tube Preamps create DC. I've been told that DC will dammage my Krell amp (FPB400cx), and possibly my speakers(Tyler Acoustics Linbrook Sig, System 1 piece). UNLESS, I open the amp up and do something to the "jumpers on the digital board" . This puts some protection into the signal path. The Bad thing is, I'm told, - it also colors or degrades the audible signal coming thru the speakers. So, if I want to use my SS set up, say for SACD or DVD-V/DVD-A, I would have to open the amp up again and reverse the proceedure. This would remove the "blockage" in the signal path. :-( This of course, would have to be re-done when I want to go back to the tube setup. WHAT A PAIN!

Needless to say, this has thrown the proverbial 'wet blanket' on my tube enthusiasm. Is this problem common to ALL SS amps? Or is it just a KRELL thing?

Any thoughts would be helpful.
(This is part of a thread i started on the speaker threads, but i thought i might have more luck here on the "amp' Threads)
Thanks
oldpet
sogood51
2,157 posts
 
You can always check your pre-amp for DC leak. I use an tubed pre with my Krell and read the same thing you did about the internal tweak..I didn't bother with it and have no problems at all.

Krell Ksa-250
Krell Kav-500

There was a thread about BAT pre-amp's and Krells, you should do a search for this one.

Dave
elb's avatar
elb
100 posts
 
Call up Krell and ask them.
rwwear
2,868 posts
 
Tube preamps can have DC leakage that's why they sometimes use coupling capacitors. And since Krell amps have no capacitors in the signal path, they can shut down when fed a signal that has DC present. This also occures with McCormick amps. I once worked at a store that sold BAT and McCormick and everytime we hooked a BAT preamp to a McCormick amp, the amp would shut down. The jumper inside the amp inserts a capacitor in the signal path with Krell. I used to use a Counterpoint SA-3 with my Krell and never had a problem without using the jumper.
drrdiamond
671 posts
 
I bought a "pre-owned" Krell FPB300 that had been used with a tube amp without doing any internal alterations.

It had to go back to the factory for repairs. Luckily, it was close enough to being in warrantee that Krell didn't charge me.

Richard
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