Recommended 12au7/5814s for Atma-sphere MP-3


I'm told these are the tubes that make the most difference in the MP-3; I have Sylvania 6sn7GTBs for those tubes in the unit. I think that how a tube sounds has a lot to do with the circuit that it is in, so I would like to hear from those that have rolled the 12au7 tubes in this particular unit; although I also welcome general comments on the 12au7/5814 breed. I have RCA Clear Tops, Siemens 5814s, RCA Black Plate 5814s, RFT 12au7, and RT 5814s, and Tungsol 5814s - I haven't started rolling yet; I have the Siemens in the unit and it seems to be very clear and spacious, but I'd like to know what other flavors I can expect with some alternatives. Thank you.
pubul57
In my Jadis DA60's 12AU7 positions, I'm running the Mullard Blackburn 12AU7/ECC82. The best sound I have gotten so far, but I still think I can do better.

Other tubes tried were Brimar 12BH7 and Sylvania Triple Mica Grey Plate 5814. The Brimars, which some folks swear by as a 12AU7 replacement were pretty bad, lack of deep bass extension, boomy mid/upper bass, not the greatest mids, and overall fuzzy and unfocused sound. I had some people over one day, and was tearing the rest of my hair out trying to figure out what was wrong with my sound, as it was just all wrong. Later that night, when everyone left, I put the Mullards back in, and everything returned to what it should be. Perhaps they are superior in many an application, but not this one.

The Sylvanias were a lot better than that, though still not on the same level as the Mullards.

None of the current production tubes (JJ, EH, Ei) I tried much impressed me.

I have some Amperex 7316/ECC186 (both halo and D getter), which are supposedly the Holy Grail in this regard, but have yet to try them.
IMO the best overall value for the MP-3's line section is the RCA clear top.

Priced NIB at $50-$70 per pair, it's tough to find a 12AU7 with a better QPR given the escalating prices of the highly prized Mullard, Amperex, etc.

As always YMMV.
I popped in the Clear tops last night and love them (in this unit), I just bought another pair and Mullard 12au7s from the Blackburn factory - I should be set. I also bought some RCA 6sn7GT - grey glass from the 1940s for the MP-3. Thank you all for your advice. I could not be happier with my Atma-sphere pre and amp; an incredible combination with Merlin speakers (and others I'm sure).
Bill, thanks for jogging my memory - a friend gave me a few of RCA 12AU7 Clear Tops a few years ago to try in this amp, telling me how great they were, and I completely forgot about them. I'll need to give them a shot...
Joe,
Thanks. In response to your first post, earlier this year I purchased 2 pair of the Amperex 7316/ECC186; one pair halo and one pair D getter.

First of all, I didn't need them. My tube inventory has reached a ridiculous number, probably close to 1,000, most of which will never be used. I plan on selling many of these within the next 2 years in order to be at a "manageable" level. Thank goodness most of them were purchased prior to the current "run" on NOS and at really stupid prices e.g. 6922 Bugle Boys for $15/pair and Sylvania 6SN7 Bad Boys for $20/quad etc. Of course this was back in the 70's and 80's.

Secondly, the Amperex tubes are great, perhaps the best iteration of the 12AU7 I've heard. If money isn't important it probably doesn't get any better. However, having heard them in a number of amps and preamps, I would not spend that much money again. There are other 12AU7 that perform admirably for much less.

YMMV