Optimizing the Prima Luna Premium Integrated amp


Having had the Prima Luna Premium Integrated for about 7 months now its been one of my goals to retire the CJ PV10A I had been using for pre amp. However from the start the preamp section of the Prima Luna never seemed to measure up to the CJ in deep bass. Recently however I decided it was time to retube the 12AU7's in the CJ, sticking with trusted NOS Mullard CV4003's. Now having 2 pairs of Mullards to play with I was able to do some comparison swapping in the Prima Luna. Lo and behold, putting the Mullards in the rear 12AU7 sockets of the Prima Luna brought the low bass up to where it should be and differences become trivial swapping a variety of 12AU7's between the CJ and the front sockets of the Prima Luna

Mullard NOS CV4003 highly recommended for the back 12AU7 sockets of the Prima Luna Premium integrated. Not so recommended for both socket pairs as the combination becomes too forward in the bass. Funkwerkes 12AU7 and Prima Luna 12AU7 are in use now while I seek a quicker more neutral tube than the Mullard for the front pair.
davide256

Showing 9 responses by davide256

Prima Luna USA posted recently that they now support KT-120 in all their line. I got mine yesterday, the first 2 hours of break in were rocky with distortion and threw 1 bad tube fault but after that they opened up and roared. They (a) remedy the PL's lack of lower bass and bass slam (b)have more percieved dynamic range and openness. I have no desire at this point to put the KT-88's back in.
so after 10 days of loving the KT-120's my pre and driver complement of tubes has been turned totally upside down. The Amperex 12AT7's are out because of audible gain distortion, all NOS Mullard CV4004's now. I've rolled the KT-88's back in a couple of times but they sound so emasculated in the bass by comparison that I'm back to the KT-120's in short order
for the Premium integrated the manufacturer tube configuration is all 12AU7's. I have swapped in some Amperex 12AT7's and Jan Phillips 12AX7WA's, in both cases
the Mullard 12AU7's were better in the front sockets. Toying with shelling out for some Seimens Nickel plate 12AU7/ECC82's.
I've continued tinkering and over the last few months of tube rolling repeated, varied A/B comparison has led me to 1 inescapable conclusion.
In the PL Premium Integrated while the GL KT-88's are wonderful tubes with tighter control than the stock PL EL-34's at the frequency extremes, they fail on voices in the crucial mid range, with a dry papery affect. This is not a judgement on the GL KT-88's as I suspect in a different amp the issue would not exist, only a conclusion that in the PL Premium Integrated they aren't the best choice.
Additionally after rolling various 12AU7's in the front sockets (Mullards, Siemens, GL, Groovetube, EH) and then trying other 12Axx varieties its become crystal clear that 12AU7's are not the best sonic choice for the front sockets. No matter what 12AU7 I rolled for the front sockets, the pre sounded compressed and sleepy compared to the CJ PV10A pre feeding the HT input. Rolling in 12AT7's gave immediate improvement in dynamics and "liveliness". Using 12AX7 was similiar but more prone to distort

Where I now get best sound is
Front pre sockets - Amperex 12AT7 (orange world logo)
rear pre sockets - Siemens ECC83 (12AU7)
power tubes - stock PL EL-34

The PL power tubes are not my final destination as they don't have the control of the KT-88's and combined with the NOS Mullard 12AU7's showed distortion artifacts which the Siemens did not.
What this configuration does well is create a lush detailed mid range, good mid bass, and a high frequency end where percussion has both hardness (blocks) and sheen (cymbals). Sound decay is good, not chopped off as it was with 12AU7's.
What this lacks is deep bass control and good "black space" around instruments. All of which I think will be improved with better EL-34's
On the fence at this point for future upgrade between between the SED Winged C EL-34's and NOS Siemens EL-34's.
I may dabble with them at some point but the combination of the Amperex AT7's with the EL34's was like when you turn a knob and it clicks into place.... so many things were suddenly right I didn't feel a need to do more than fine tune the back 12AU7 choice for cleanest sound. I am hoping that when I upgrade the EL34's that the Mullards work well again as they were superb with the KT-88's.
so just an update on current tube rolling. The KT-120's continue to sing...just plain better than the cryo GL-KT-88's all around in the amp. And tube distortion in the pre section is more mercilessly exposed. I've acquired some ribbed plate Telefunken 12AU7's for the back pre sockets, cleaner, better bass, more detail that the Siemens I was using. Flipped my entire inventory of 12AU7's through front sockets again with the Teles in back... 12AU7's just sound wrong in the front sockets, low level details fuzzy, more distortion. Had settled on some Mullard 6201's (12AT7) in front, after putting Telefunken in the back sockets they were still detailed but too bright and I isolated them as a source of low level tube distortion. The Amperex world globe 12AT7's are now back in as more musical but their bass waffles, highs are a little rolled. Likely to pop for Tele or better Amperex tubes in the next 30 days.
At this point with the Teles in I have achieved my goal of retiring the CJ PV10A pre and using the PL pre section
Alright, if you have this amp, listen up. Running NOS (1960's)Siemens 12at7 tubes with triple mica in the front sockets and Telefunken 12Au7's in the back sockets is a match made in heaven. Gobs of low level detail, no tube distortion, no edginess and superb low bass tone colors. The CJ PV-10A is completely retired now, sounds veiled compared to the PL integrated with this tube configuration and Rel cap upgrades. Nice to be finally satisfied and ready to focus on other system areas.
Back to this thread after a while. In the past year I have made the following changes

1) the front 0.22UF caps are now clarity CAP MR's
2) the follower 0.1UF caps are Rel CU caps with 0.01 TFT vCAP bypass caps
3) the power tube 0.22UF caps remain Rel theta's because of space limitations but bypassed with Rel Teflon 0.022UF caps

As these changes were made it became clear that the 12AT7's did add distortion, I now run Telefunken 12AU7's for all pre-sockets.

This is detailed, airy but it does not match the CJ for lower midrange weight, had similar criticism when I had Rel 0.22 teflons in the front sockets before the MR's. I have ordered some VCap CU's to replace the Clarity MR's as these are reported to shift balance to improve lower mid range, will report back in a few weeks after they are installed and have some hours on them.
The VCap CU's have been installed now about 5 days and I have about 20 hours on them. This is a very different experience than other capacitors, gobs of impressive but natural background detail. Oddly they seem to require more power for same volume levels but I have seen this before where old gear was masking signal, emphasizing loudest instrument and new gear in showing more detail, and correct harmonic overtones is consuming power across more spectrum. Very pleased, the CJ PV10A pre can no longer compete, sounds colored in comparison. WIll have to be patient as all I read about others use of VCap states 100 hrs as minimum break in time.