New Prima Luna Amp In Distress / Me Too

For the record, pencil tapping did not work with this case. Just a bad tempermental tube. Thanks all. Case closed.
- Mario

thanks for the reponse,,I ended up with a 3 month old prima one ,and I like it very much over my previous 25 watt tube intergarted ,,but I was wondering about tubes,,I am sure this thing can sound better then eh 12 ax7 in the front,,I had telefunken 12 ax7 and when i plopped that tube into the mix i found a more musical sound,that is in my previous amp,,,so I spoke to kevin,,he said give it a while with stock tubes but he likes ge 12ax7 long plate tubes with mullards el34's,,anybody out there let me know what you tried,,

Vm8444, I've already mentioned the tubes I prefer in the One...nuff said. However, if you do some checking I think you will discover that the SED EL34's are a Mullard copy and the EI's are a Tele copy. These are inexpensive new production tubes and I recommend them highly for what they are, without regard to the Prologue One. But, if you've got the money to spare, that NOS recommended to you might float your boat as well or better.

thanks newbee,,loving my prima one,,currently still using stock tubes ,,but I am getting the itch to roll,,maybe the cv4004 mullards,,and maybe slvania 12ax7 ,,then we'll see about output tubes later ,,thanks bro.
v

It’s been a few months since the original faulty tube has been swapped out with a replacement KT-88 sent by Upscale Audio. Things sailed along smoothly until last week when another stock KT-88 tubes began popping and demonstrating the same problems.
After checking with Kevin at U.A., he suspected it might be vashode powder. On close examination, this turned out not to be the case (at least, as far as I can tell).
At any rate, since this latest intermittent failure began in the same socket as the first one, I’ve decided to replace the entire power set to rule out any “hot seat” factor that might be emanating from the amp while it’s still under warranty. I’m going with Valve Art Kt-100s which are a rugged Chinese copy of the old Genolux design KT-88.

Whether this ends up to be just an unlucky set of stock tubes or a problem with the Luna, I’ve come around to thinking that this may be the challenge that one sometimes has shoulder in tube audio.

It should be noted that Kevin reports that, outside of a few PL Kt-88s demonstrating a similar problem with Vashode powder (none in the PL-EL-34s), the Prima Luna Amps are demonstrably good builds with few problems. In fact, I’m not in a panic about all this – learned a lot about this amp through troubleshooting – learned also that when it’s on song, it’s absolutely warm and lush and competes with the best of ‘em.