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Audio research and krell

So here goes I have a arc ref 5se and I am using a krell Kas 300s and recently I noticed the krell was making some noise when powered off so I made some calls to krell and found out that the older krell amps are not recommended to be used with tubes I have never heard this .so has anyone here heard this .second  question if that's the case what should I move to for a new amp I like the krell sound. Speakers are revel salon 1 transparent cables

tunawishing
erik_squires
16,041 posts
 

AFAIK, Krell is DC coupled. If your preamp puts out any DC at all it can cause a problem. The solution is really simple, put a cap in series. 2 to 4uF should do.  Get as fancy as you'd like. :)

sbank's avatar
sbank
3,378 posts
 

I run a BAT VK51SE into a Krell FPB-300 for years and have never had an issue. FWIW, the Krell outperforms my previously owned Lamm hybrid monoblocks, especially in the bass performance feeding low efficiency, hard-to-drive  electrostatics.  Cheers,

Spencer

unsound
7,329 posts
 

Some Krell amps actually had an internal jumper to add a capacitor to the circuit when using tube pres to avoid DC issues.

sbank's avatar
sbank
3,378 posts
 

@unsound You're correct. The FBP-300 has this. I forgot to mention that. Good callout! Cheers,

Spencer

invalid
1,180 posts
 

I believe krell added that jumper during the production of the ksa 250, because a certain model BAT preamp was causing DC issues, not all BAT models were a problem just one model if I remember right.

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