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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
pubul57 OP
3,712 posts
 
The Mullard is the one obvious pair I do not currently own that I do want to try. Are they all the same (CV4003 and the 12Au7s), any good sources? Does seem like Andy at VTS carries them. I agree that the Amperex would be great to own, but the prices and scarcity makes give up on them. The Mullard's seem to be more accessible. If I could find some strong matched GTBs I would also give them a try, if they are warmer than the GTBs it might work well with the Siemens.
rodman99999
3,557 posts
 
You may find some of these observations useful:(http://home.comcast.net/~gillespie147/12AU7-Preamp.html)(http://home.att.net/~chimeraone/6sn7sound.html) I've tried the top 8 tubes on the Chimera list. The RCA, Raytheon and National Union VT-231's(all 40's, bottom getters) would definately please your aural tastebuds.
pubul57 OP
3,712 posts
 
What makes a bigger difference, the 12au7s in the MP-3, or the VT-231/6sn7s in V1 of the M-60s? That is, which would you after first? I also read somewhere that VT-231/GTs were prone to microphonics compared with the GTA/Bs.
tvad
9,467 posts
 
I also read somewhere that VT-231/GTs were prone to microphonics compared with the GTA/Bs.
Pubul57
That's certainly been true in my MP-1. I've tried two pairs of Tung Sol VT231 round plates and two pairs of Ken Rad VT231 black glass, and 5 out of the eight tubes have been microphonic in the front position of the MP-1.

When non-microphonic versions are discovered, they may offer excellent sound, but I'm quickly concluding that for me the hassle of finding them (not to mention their cost) is outweighing the slight benefits.
pubul57 OP
3,712 posts
 
So what 6sn7s have you settled on for the MP-1? I'm using the early production Sylvania GTBs - stick with this and focus on the 12au7s? - I'll be looking for some Mullards based on comments so far.
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