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PRIMA LUNA DIALOGUE PREMIUM - 20 minutes and then loud pop and buzzing in 1 channel

Hopefully someone can help.

Amp is virtually new. The amp will operate wonderfully for 20 minutes and then a loud pop , and then buzzing from the right channel. I shut down the amp and then it repeats.  I switched some tubes and it is still there.  I switched the cables and know for sure it is only one channel, the right one. The buzzing does not increase with the volume increased. . 
It is the amp and not the Prima luna preamp.  Cables and connections are fine.   Pushing Focal Kanta No2's . 

Any help would be very much appreciated. I'd rather not send a 68 pound piece of equipment through the mail. 

Thanks lot - Craig 

128x128vespacraig1966
missioncoonery
1,215 posts
 
Sell it now,seems everyone else is?..So you suggest dumping it on someone else and taking a huge loss..stupid comment at best.Prima luna makes very good products,ive had several.
tablejockey
3,883 posts
 
"Sell it now. Seems everyone else is. You see how many are for sale?"

Listings on Agon,AA,USAudio-ZERO

Perhaps this poster is being facetious? I've used PL products for years without problems,along with many others
Hopefully, it is something simple. Doesn't look like the OP has completely eliminated a bad tube.
vespacraig1966's avatar
vespacraig1966 OP
8 posts
 
In response to tablejockey, regarding not switching out every tube: I have replaced all el34's with 4 brand new Tung-sol kt-150's.

I have taken each 12au7 from the left channel(which works fine) to the right problematic channel,  and the pop then buzzing continues. 

Does anyone suggest buying a 1/2 dozen brand new 12au7's?   
Please respond. Thanks Craig 
newbee
4,767 posts
 
Craig, It sounds like you have done enough to rule out a faulty tube as being the source of your problem. That said you are really going to have to have a tech diagnose and repair the problem. If you did not buy this from a dealer I doubt that Deal is going to repair it. He wouldn't work on one of my units which I bought second hand. He did, however, refer me to a tech in the LA area to whom I sent the unit and had it repaired promptly and at a fair price. These units should be easy service so if you have a tech in your area who knows tube amps you could probably have it done locally.
kalali's avatar
kalali
1,977 posts
 
This might be stating the obvious, but are you sure the amp is designed to work with KT150 tubes?  Either way, it might be worth trying it with the stock EL34 and see if the problem still exists.
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