Primaluna dialogue premium HP tube rolling suggestions to reduce brightness

Suggestions to call Upscale is a start.

Since Kevin is the distributor and offers tubes, he can suggest something that also won't break the bank. V11 &12 are the biggest influence other than the power tubes.

Perhaps some of the new production are good deals instead of pricier NOS?

I don’t believe output tube rolling is the answer to the OP’s problem, as the below will still be there and explain.

One must remember speaker and the speaker wire introduce not only a resistive load to the amp but a capacitive one as well. ESL’s even more so capacitive, so all amps theoretically should be unconditionally stable, eg no ringing whatever the load on bench square wave tests.

In Ultra linear mode this amp is a little unstable into 10khz 8ohm pure resistive loading, even without any speaker/wire capacitive loading which would exaggerate this ringing even more which may cause the brightness heard.
http://www.stereophile.com/images/214PLDPfig03.jpg

But in triode mode it seems to be a bit more stable, and should not sound as bright, but still we don’t get to see it with some capacitive loading just 8ohm pure resistive.
http://www.stereophile.com/images/214PLDPfig04.jpg

Even JA "Stereophile) who did the above measurements said this
" PrimaLuna DiaLogue Premium performs at its best with tubes operated in Triode mode."

One can clearly see in ultralinear mode the sharp rising frequency response after 20k this is the rigging seen on the 10khz square waves. "It a bit like an uncontrolled resonance peak of some metal dome tweeters" "brightness???"
http://www.stereophile.com/images/214PLDPfig01.jpg
It seems to me that in Ultralinear mode they’ve gone for too much bandwidth (70khz) at the sacrifice of stability.

But in triode mode all is far better behaved, with no peak after 20k.
http://www.stereophile.com/images/214PLDPfig02.jpg

If I owned this amp I would only use it in triode mode, and if that didn’t have enough power, I’d get another amp that was.


Cheers George

The stock Primaluna Preamp tubes in the 2 middle slots were way too bright for me. So if you want to go with new production tubes. I would suggest the reissue Mullard 12au7's. If you want to experiment with old American tubes. You might want to seek some Baldwin or Conn organ pulls for less than $30 a pair. Triode mode will help as suggested.

George HiFi-  since you seem to have a better understanding to the technical concepts, perhaps you can explain this to me. The amp has output terminals for 4, 8 and 16 ohms.  While my proacs are 8 ohm, when I run them using the 4 ohm terminals, they sound better - bigger soundstage, more air around the instruments.  If it matters in the equation, my set up requires me to run about 4 meters of speaker cable (I cant place the amp next to the speakers)- which I am using Kimber 8TC bi-wired.

Everyone Else - I have reached out to Kevin at Upscale about the V11&12 tubes and will see what he recommends. I will check out aniwolfe's source, too.  When you say the re-issue Mullards- are these the Russian made tubes? 

@meiatflask

Yes the Mullard reissues are Russian. Jared is usually my go to guy at Upscale when it comes to tube recommendations. Kevin can be difficult to get an good answer from. Just my personally experience.

Also I want to add. You shouldn't be forced to use only Triode mode with your amp. If so, then what's the point of owning it? I prefer to use UL most of the time.