Calling all krell knowledgable persons

[Jbl4345fan]

Hello all I bought back in September of last year a krell fpb-300. I was told all caps and transformer was replace by krell. I didn't connect the amp until I bought my luxman c-1000 three months ago. Well I bought a audio research sp3-a1 today was sounding pretty good. I was on the phone and I believe I heard 3 pops and the amp cut off. Anyone ever heard of not using a tube amp with krell fpb-300 power amp. All opinions are welcome. I need HELP!!!

 

[Nyjblbob]

Actually an SP3A pre is just what a High Quality Krell amp needs to add some life into it
I use one as a daily driver
I’m sure there’s something else going on with that amp

 

[GordonW]

The only possible problem, could be if a coupling cap failed in the preamp, and is allowing DC voltage to be imposed on the output. Solid-state amps definitely do NOT like DC fed into them...

Regards,
Gordon.

 

[gadget73]

this does use output coupling caps for DC blocking, so thats a fair guess. I believe they are all film caps in stock form but its old enough that one could have failed.

 

[Jbl4345fan]

The only possible problem, could be if a coupling cap failed in the preamp, and is allowing DC voltage to be imposed on the output. Solid-state amps definitely do NOT like DC fed into them...

Regards,
Gordon.

Thanks. A friend of mine said the same thing. Going over his house Saturday morning to find out

 

[Jbl4345fan]

Thanks. A friend of mine said the same thing. Going over his house Saturday morning to find out

I did notice the amp running hotter than normal once I did connect the tube preamp.
I love the sound of this audio research sp3-a1 but it's lacking a little in the bass department .

 

[gadget73]

that might be something more about the input impedance of the Krell. The caps at the output and the load impedance of the amp form a high pass filter. Too low of an impedance at the amp and it starts cutting out the bottom of the audio signal. Maybe you could increase the value of the caps in the preamp, but it only has so much ability to drive a load.

 

[Jbl4345fan]

The only possible problem, could be if a coupling cap failed in the preamp, and is allowing DC voltage to be imposed on the output. Solid-state amps definitely do NOT like DC fed into them...

Regards,
Gordon.

My friend checked out my audio research sp3-a1 no dc leakage. Every cap has been replaced.

 

[birdman99]

I know this is an old thread but Krell has this in fpb owners manual. [ page 9 ]

Excessive DC level in a signal can damage amplifiers, speakers, or both. To combat this potential problem, the Full Power Balanced amplifiers include internal jumpers that insert coupling capacitors into the signal path. These capacitors should be engaged when using a tube preamplifier with a Full Power Balanced amplifier. If not utilized, KRELL reserves the right to refuse warranty service due to DC related damage. Please contact your KRELL dealer for assistance.