Channel unbalance with Primaluna Two

[Stahlhelm]

Hi,

I've just discovered a serious problem with my Prologue Two.
I have an analogue setup using a Rega Planar 3 as the source. I was testing my anti-skating setting on the tonearm with "Hi-Fi News Test LP" track no 6 (300 Hz signal at 12dB). I had a multimeter on each speaker's terminals. One the right channel I read 100 mV, on the other 80 mV (multimeters are Fluke, good brand, not a toy). I tried to work it out with the anti skating knob on the tonearm, but I couldn't.
I swapped over the speaker cables, and again the right channel was louder. That told me that something is wrong with the Prologue.
I also have a solid state amp, I swapped over: left channel 99 mV, right channel 100 mV.
Using the Prologue the difference between the two channels is big: 20%. I can hear that the soundstage is pushed out to the louder (right) speaker.
I swapped all of the tubes from left to right but the problem remained on the same channel.
I am really stucked here... Get new sets of tubes or return the amp for repair?
Does anybody knows the solution?

Thanks

 

[RobHolt]

If you've swapped the tubes over and the problem remains then you have an ampllifier fault and it should be returned/serviced.

Unless you are confident performing diagnostics of valve circuits I wouldn't attempt a DIY repair due to the high voltages flying around.

ZG needs its members