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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
dekay's avatar
dekay
2,959 posts
 
Nice (inexpensive if purchased on Ebay) Mullard Blackburn 12au7's are the late 60's/early 70's which often have Amperex Orange Globe labels.

Can't access my tube cabinet right now, but the pair I'm currently running have GF2/B1K1 etched codes (early 70's).

They sound more like an Amperex Holland 12au7 than a typical/earlier Blackburn 12au7.

5-6 years ago you could buy NOS 5 counts on Ebay for $20, or so, as most thought them to be Richardson relabel's and/or fakes (the auctions did not mention the etched codes)

I thought they were of either RFT or Japanese manufacture, due to the sloped getter and dark flashing, only to find them to have Blackburn codes.

The Holland Orange Globe 12au7's of the same time period would be another good/inexpensive bet.

Look for TV-7 readings of over 100, per section, for an as new tube (my sealed units were typically between 105 & 110).
pubul57 OP
3,712 posts
 
Is Blackburn the factory of choice for Mullard 12au7s?
tvad
9,467 posts
 
Is Blackburn the factory of choice for Mullard 12au7s?
Pubul57 (System | Threads | Answers)
Blackburn is the factory of choice for all Mullard tubes, IMO.
pubul57 OP
3,712 posts
 
Any experience with mullardtubes.com? I've seen them advertise here recently, but I've not heard them mentioned by any users, yet.
trelja
3,215 posts
 
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.
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