Primaluna dialogue premium HP tube rolling suggestions to reduce brightness

part of the brightness in the PL Dialogue and HP are the use of the SCR coupling caps. If you swap those out for Jensen Copper foil, you will get a midrange to die for and a 3 dimensional and airy top end.

The first AU7 (center two tubes) will have the largest affect on sonics, so maybe start there first with some Mullards. The 2nd and 3rd position sockets will have a lesser effect on tonal balance. Perhaps as some others suggested, use some RCA clear tops (used by many organ mfgrs back in the day) in those other slots.

@johnss

I personally don’t want to mod my amp. Have you experimented with any fuses? I wonder if there is a fuse that would help with brightness?

There are so many things that can be altered outside of modding the amp.

meiatflask

Hi, to answer that properly without guesswork, I tried to find an impedance graph of your "proac tablette anniversary" speakers, but with no luck.
While they are factory rated at 8ohms there could be dip/s maybe to 4ohms maybe in the power regions, and the 4ohm tap from your amp then has a better damping factor (output impedance) to control them at that frequency.

Just go with the 4ohm tap in Triode mode, as this amp is questionable for capacitive stability in Ultra-linear mode. As Stereophile has stated, if you find you don't have enough power, look to either more efficient speakers or a bigger amp. Don't go wasting money on different tubes they will not fix the instability in Ultra-linear mode.  

Cheers George

I disagree

You got a $4500 amp. I say try a CV4003 Mullard or RCA, Raytheonl blackplate organ pull on the cheap.

The chinese 12au7 tubes are to draw attention at first with all the high freq detail, but they are fatiguing...especially the 2 middle ones.

Upscale audio offers a cryogenic treatment.  Any comments on how it will affect sound?