tube pre amp and Krell FPB 600


Krell in its reference manual says : Tube pre amplifiers , by design, are capacitively coupled. For this reason, the benefit of a direct coupled amplifier can not be realized when used with a tube preamplifier. Additionally , many tube preamplifiers output a great deal of DC. This DC may exceed the servo of a FPB amplifier. Excessive DC level in a signal can damage amplifier , speakers , or both.
Can I use Air tight ATC 2 pre amp with Krell FPB 600 ?
Please advise.
Thanks
fpooyandeh

Showing 3 responses by atmasphere

^^Even if you have solid state you can get a thump. The reason you don't is your preamp has an automatic mute.

Many tube preamps do nowadays too.
The input of the Krell is direct-coupled (no coupling caps). This is why they are 'concerned'. However, the claim that tube preamps put out DC is ridiculous. They no more do that than solid state.
Salectric, Historically tube preamps have been in use with solid state amps for **decades**! Solid state amps by their very nature have to have a protection circuit, and there aren't any warmup thumps that a tube preamp can make that can damage the input of a transistor amp. The protection relay is there to protect the speaker, not the amp.

Ever tried turning on a solid state preamp after the amp is already on? They thump too!

Singling out a tube preamp when solid state preamps are just as guilty is ludicrous. Ct0517 got it right- **no matter what kind of preamp you have**, it gets turned on and stabilized first before you power up the amps.

I think you will find that all preamp manuals state something to this effect unless the preamp has a warmup mute feature.

That statement in their manuals is misinformation in a very pure and refined form.