Krell FPB400cx coupling capacitors question

I wouldn't use the coupling caps unless your tube pres have a problem.

many tube pre amps will pass DC your best bet is to call Krell to get the facts.

I have ARC Ref 3. I have once called Krell and they told me that it is OK to run ARC gear without the caps.

Most modern tubed preamps catch the DC at the output and will not give you any problems with your amp. I have used 3-4 tubed preamps and not had any problems with my amps. It should be easy to find out the amount of DC at the output of the pre and check with Krell.

I have a FPB700cx and used several tube preamps with it. If you're nervous, check the DC output of your preamp with a good (Fluke) multimeter.

How much DC volts should I expect to see? Could you let me know the reading value of MIN and MAX? Thanks

There is no minimum-the lower the better. My Bat preamp measured 0.002 Vdc and I haven't had any problems. I would guess anything below 0.01 or so would be fine but I'm not an expert. I talked to Krell about this and they were totally non committal.

Have anyone have any experience upgrading the Krell input coupling caps ? Can you share your experience ?

take the cover off the pre-amp, look at all the out-put tubes only, if they have coupling caps, one to two next to the out-put tubes, you will be fine, these coupling caps are designed just for DC out-put, as a matter of fact, if your pre-amp has the coupling caps on the out-put tubes, you will have no dc reading what so ever, then you can use your Krell with no issues, it is impossible for Dc to pass with DC coupling caps on the out-put tubes, how do I know?, I use a tube/solid state hybred cd-player directly to my krell 700cx amp, my player has two DC coupling caps on each out-put tube, blows the doors of most pre-amps performance running direct like this!