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

I haven't tried many 6SN7. Presently, I have RCA 6SN7GT grey glass from Andy Bowman in the front positions, and stock Chinese 6SN7 in the remaining positions.

All my 12AT7 in the phono are still stock Chinese, but I have a pair of Mullards on the way to try in the rear position.

If you desire a warmer sound from the MP-3, I'd suggest trying some Mullard 12AU7. It won't be mushy, bloated or ripe. If they perform in the MP-3 as they have in my other components, then the effect will be like a spring warming.

Thanks Tvad. I'm going to give the Mullards a try (either CV4003 or 12au7).

some of the great 12au7s i've found are the cbs/hytron 5814wa, rca 5814 triple mica blackplate, rca command 5814a triple mica blackplate,raytheon 5814 blackplates triple mica,brimar 13d5, raytheon 12au7 blackplates.

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).

Is Blackburn the factory of choice for Mullard 12au7s?