Left Channel Out Primaluna Dialogue Premium

Hey folks.  So I turned on the stereo last night ready to listen to some tunes when it was clear there was no volume at all coming from the left speaker.  Right channel sounds just fine.  I did some speaker/cable/source switching and swapping and determined it was the integrated amp.  It’s a Primaluna Dialogue Premium which is the predecessor to the EVO 300.

I swapped out all the tubes, still nothing.  Did some research and stumbled on some info regarding the fuse.  I can replace that today but if it was the main fuse, wouldn't both channels be out?  

I came across a similar thread on here from @whacky who mentioned a left and right channel fuse.

”There are separate fuses for the right and left channel. Not just the main fuse. they are contained on inside a small fuse holder on the left and right side after you open up the underneath.”

Problem is, I can’t seem to locate an internal left or right fuse.  Nor can I locate any kind of PL schematic that shows where this fuse might be.  I have a message into Upscale and maybe they can point me in the right direction but I thought I would reach out to all the fine folks here for some assistance. 

Any other thoughts as to what the problem might be?  If it is a left channel fuse, where is that guy located?  Thanks for your help!


I'm sure you're right.  I just thought someone out there might have a potentially quick solution for me.

I will never agree with @aniwolfe on this one as I have gotten lots of wrong answers from the supposed experts. Sure ask them, but be prepared to go "hummm".  But maybe they will have a good answer.

This amp doesn't have a tube rectifier, which could be a suspect.  I'll link a photo of the insides.  I don't see any internal fuses or obvious suspects. 

Hopefully Upscale will say, "sure, this happens all the time and it is the ______."


FWIW, IME, you have a power tube failure which has tripped your fuse (?) in the bias circuit. I,'m not sure what the 'fusing' is for your unit. I have two PL's, one with a fuse and another with a circuit breaker type which supposedly just needs to reset itself. Mine with the 'curcuit' breaker type' has failed twice and needed to be repaired by a tech. Upscale can either fix (depending where you bought it) or recommend a repair agency for you. Good luck.

Thank you all for the pointers.  I've been emailing back and forth with Upscale.  They've been very responsive and hopefully we find the solution.  I'll report back once the problem has been fixed.

We just fixed and upgraded a Prima integrated amp a month ago.

I can fix/repair or upgrade if you want.

We are in New Jersey.

I can also put you in touch with the guy who we did it for.

I believe he found me with a post on Agon.

PM me if you want






i’ve had exactly same issues like you with the Primaluna Evo 400 preamp before. I did swap tubes and change the cables but it didn’t work. And you know what, I’m thinking about may be there is issue with the tubes, and I waited until late night , I turn off the light and turn on the Evo 400 and I spotted one of the 12AU7 is die on one of the tiny diodes. And I just ordered one 12AU7 to replace and the problem is solved . Hope this helps. Sorry for my English. ;))

@bryannguyen It might be one of the 12AU7 tubes.  I’m hoping that’s the case but I’ll take a closer look at everything tomorrow night.

@bigkidz I sent you a pm


I would think you need to turn amp upside down and remove some screws and check the fuses that protects the circuit in case of a tube failure. I don’t have a Primaluna but would think all tube integrated amps may be similar. 

I have a Conrad Johnson cav45 S2 and had same exact thing happen. I watched one of the left power tubes red plate and left channel went out. Right channel never skipped a beat and kept on playing. 

I called Conrad Johnson next day and explained what happened. They told me to replace fuses with very specific fuse and there is nothing to worry about. I told him it was a shame I lost one of my 1960’s Mullard fx2. His reply was tubes red plate sometimes and take out fuses just plug the fx2 back in. I was very skeptical about my tube. I ordered about 10 fuses. When fuses came in I plugged in fuses and tube that red plated and it’s been running no issue for almost a year. Good luck I’m sure you will have it up and running very soon.


If you have “spare” or extra 12AU7 tubes, try to spot which of the left three 12AU7 tubes is not lit up and replace that (power off and after 5 minutes of course).  If you don’t have spares, I would swap the left 3 12AU7s with the right.  Taking note if numbered 1-6 from left to right, swap 1 and 6, 2 and 5, 3 and 4.   See if now the Right channel doesn’t work.  Like what BrianNguyen said, turn off all the lights and see which tube isn’t lit up on the left side.   Good luck brother.  I have the same exact PL Dialogue Premium and love my amp.   

@paulcreed unfortunately this model only has one main fuse so I can think that’s the problem.  

@pangeek thank you for the good wishes and yes, it’s an amazing amp!  I really love it!  Sad it might be out of commission for a short time but hopefully not long.  I will try your suggestion later tonight when I’m home again.  I do have four spare 12AU7 tubes so maybe I can narrow down the issue with them.


I've owned the PL HP for 6 years. 

Channel went out and it was an auto bias board. It's one of the suspects that will make a channel go out.

Take it to an authorized tech. Mine fortunately happened to during warranty period.

@tablejockey good to know!  Hope it's something that's easily and quickly fixed.  I'd hate to be without it for an extended period of time.

Switch left and right speaker wires. If the problem persists, then get your LEFT ear checked :)

@pangeek thanks for checking in!  So I sent the PL to Peter Rippa, aka @bigkidz to Vu Jade Audio in NJ.  It was nothing catastrophic.  I think it was a bad relay but I’ll wave my HIPPA rights and invite Peter to describe the diagnosis more accurately if he would like. 

I would imagine I’ll have it back sometime next week.

@paulietunes  The relays seemed to be working fine but the wiring was not able to transmit the signal.  BTW I just finished the unit upgrades last night.  Sounds really nice so far.  I will let it place to make sure everything is fine and then let you know.  Maybe I'll keep it for a while and enjoy it!


Haha!  As much as I'm looking forward to getting it back, you should enjoy it for a bit!  So happy to hear it's in great shape now and thank you so much for your great service, Peter!

That is amazing news.  And great idea to throw in some upgrades.  Wish you were near us too.  SF Bay Area.  Lol 

I'm all about any upgrades especially if it's in for service anyways.  I really love that amp.

Thanks Peter.  I will when I’m ready as well.  Totally satisfied with my PL Dialogue Premium for now.  Cheers

Just to provide an update.....I received my Primaluna Premium Integrated back last week from Peter at Vu Jade Audio in NJ.  Amp is working perfectly and Peter @bigkidz was a pleasure to work with.  Feel free to reach out to him for any repairs or upgrades.