Odd problem! Any experts?

[Tim F]

Hi all, this is one for the experts. Not sure if there are any on here but can’t hurt to ask…

I have v140 monoblocks with a Ref 6 pre. I have a bizarre issue and wondered if you’d seen it before. I hope my explanation will make sense. I’m in the uk and have had this amp looked at twice now, by the main arc repairer in the uk and another hifi shop who are well respected.

One of the monoblocks is really noisy whilst playing music and when not. It is whining and cracking very loudly at a constant volume. This happens when the preamp is on and not muted. It happens when cold and warm. If the pre is muted it doesn’t make any noise at all. If I switch preamp channels around it always happens only on the same monoblock. I have changed all valves over between monos and same problem with that amp. Amp is biasing correctly. Preamp has new valves in. So now onto the odd behaviour, this is only happening when in conjunction with my ref 6. I have another old pre and there is no noise with this. So it seems to be a combined issue.

I hope that makes sense! It’s as if the ref 6 is passing noise down and only one amp can’t deal with it.

Any thoughts?

 

[Addicted to hifi]

I wish I could help and hopefully someone here will.cheers

 

[RogerD]

Hmm ,
Have you tried just using one monoblock and switching between the left and right Ref6 outputs? Try to isolate the problem....
Otherwise it could be a bad capacitor,resistor In the signal.path
Just a guess
Good luck

 

[Tim F]

Turned out to be a single component with solder failing in one power amp and was easily fixed. Also the main valve had failed in the preamp.

 

[Nemal1]

Glad your problem was identified and resolved. Both amps and line stage are excellent