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

Well, it has been some time, and I have tried all sorts of 6SN7 and 12AU7 combinations to get the sound the suits me best using the MP3 and M60s. I have tried Sylvania and RCA GT, GTAs, and GTBs on the amp. The best combination for me was two RCA GTBs in the front and two Sylvania GTBs in the rear with GE 6AS7s from Roger Modjeski. In the preamp, the best sound for was the RCA Cleartops with RCA GT Greyglass, but frankly all the RCA variations sounded good to me and I preferred them to the Sylvnias in the preamp - that might have to do with the fact that I am using Merlin VSMs and the "warmth" of the RCAs just suits the speakers, especially the tweeter, better than the tipped Sylvanias. That being said the system sounded mighty good no matter what I put in there and I would say triode balance and quiet tubes are as, if not more, important, than the brand I chose. Once that is taken care of, the hairsplitting and preferences can take place. I think I'm set for now, but I do think I've got the Atma-sphere setup sounding as good as I can get it, BUT, tomorrow or the day after, I will receive the Amperex 12AU7s, we'll see how they do compared to the Cleartop I have in the MP3 and the RCA Blackplate 12au7s. Thanks for all the advice. I just wanted to add that in my search for tubes (for my Music Reference RM9SEs as well) that you can't do much better than working with Roger Modjeski, Andy at VTS, Brent Jesse, Jim McShane, and Jim Sutter. All fine gentleman, knowledgeable, an perhaps most importantly honest.

If there is no "danger" I will give them a try in the 12au7 slot. Thanks.

12BH7s have twice the filament current, but you should be able to run them. They are based on the 6SN7 geometry- I'd be interested in what you think.

Rodman99999, or anyone else, will the 12BH7 tube work in the MP3 as a replacment for the 12au7? Is that a safe replacement? Ralph?

Isn't it great having gear low enough in distortion that even single tube changes are made transparently obvious.

Now - if you have a phono section in your MP-3, just wait until you start rolling phono input load resistors. Thats as much fun and a lot less expensive. :-)

Tim

Well, it started with a question and now I have taken the plunge. I'll be using Mullard 12au7, RCA Blackplate 12au7, RCA Cleartop, RCA 5814, and Siemens 5814 and mixing and matching those with RCA 6SN7 GT Greyglass and Sylvania 6SN7GTA early on the MP-3 - all fun and games as I find the best combination for my ears. On the M-60s I will be using RCA 6SN7GTBs on the front tubes and Sylvania 6SN7 GTBs on the back tubes with GE 6AS7s matched by RAM Labs. Thanks for you comments and private e-mails. And by the way, the units sounded pretty darn good with the Chinese tubes the units came with.

In the MP-1, starting from the rear, the 1st two positions are wired differentially within a tube and the 2 tubes are then in parallel. This is the bottom of the cascode. The 3rd tube is the top of the cascode. So the 1st two make the most difference.

In the MP-3, the 1st tube from the rear is the bottom of the cascode differential, and the 2nd tube is the top.

Generally speaking the noise importance of the tubes decreases as the signal progresses from the rear to the front of the unit, but that is not to say that the final tube is not sensitive to noise.

Generally we advise people to stay away from NOS in the phono section because of tube aging. In this case, not the NOS tubes, but the OEM tube, which is Chinese. Unless those tubes are new, they will be noisier than they should, so often NOS tubes replace them, and then the preamp gets accused of being noisy when really what is happening is the NOS tubes, while being quieter than the OEM tube (which might have gone down hill its own self), are still not quiet *enough*.

That is not to say that you can't find NOS tubes that *are* quiet, but they are rare these days.

Jtimothya, great reading on that link. Thanks.

I haven't done much rolling with my MP-1, but I'm using a Raytheon 6SN7 in the forward position(differential amplifier where all LS gain is performed), a matched pair of 6SN7EH in the circlotron, and 6SN7EH in CCS. IMO the latest EH production sounds clear, extended, & musical. The front 6SN7 is a good place to experiment with NOS tonality. In the phono section Mullard 12AT7(selected for low noise by Jim Mcshane), improvement upon the stock Chinese tubes both in quietness & sonics. The first two 12AT7s in the phono section circuit are in parallel, forming together the top half of a cascode with the third tube. When rolling the phono stage, you would probably want to replace the first two 12AT7s with the same type of low-noise NOS tube.

I have Herbies on every tube for good measure. I did spring for the RCA GT (Grey Glass - 1940s)that are suppose to be very well matched and I'm keeping my fingers crossed, quiet. I think I'm going to stick with Sylvania early GTBs for the M-60s, though I might roll some GTs in putting them into the mix helps. Is everyone in agreement that GT/231s (assuming they are quiet and well matched sections) generally sound better than GTA/Bs?

I have an MP-1 which does not use the 12AU7 so I cannot compare the relative influence of those tubes with the 6SN7.

In the MP-3 I believe the two sections of each channel's 6SN7 are part of its circlotron output with each cathode in a tube handling one-half of the wave form. (Hopefully Ralph will correct if thats wrong. :-) Thus, it is v. important there be a decent match between the sections within that tube, and that the tube be quiet. As Tvad notes, 'quiet' is a critical attribute - moreso for the preamp than for the amps - so a dealer (such as AndyB at VTS and others) who will screen for noise may save you some money in the long run even if he charges a bit more for the tubes.

The brand/vintage of each channel's 6SN7 will have a real impact on the preamp's sonic character. Some contemporary tubes are 'not bad' - eg., I and others who've tried the Electro-Harmonix 6SN7 find it tends toward a timbre not far from a Sylvania GTB. However, quiet NOS versus a Chinese or Russian 6SN7 in that position, is, imo, not much of a contest and for me NOS are worth the extra rubles. While you can spend a lot of money on the more exotic 6SN7 varietals (bad boy chrome domes, round plate tung-sols,'W's, etc.) a couple nice Ken-Rad, Sylvania, Raytheon, or RCA GTs/VT-231s shouldn't break the bank - especially if you start with used tubes to learn your own sonic preferences. If you haven't seen the head-fi 6SN7 thread, you can read it here.

Fwiw, I've found Herbies tube dampers do their thing nicely on the line stage tubes as well as in the phono section. I use them on 6 out of the 10 6SN7s in the MP-1's line stage, and on 6 of the 8 12AT7s in the phono section. Best of luck tube rolling your new MP-3!

Tim

While I understand that to some extent, every tube matters, do the 6sn7s make as noticeable difference in the MP-3 compared with the 12au7s? That is, are these slots worth spending NOS money on?

On the M-60s, do the front and back 6sn7s (V1? V2?)get equal billing for NOS upgrades, or are the V1 spots more sensitive in terms of impacting the sound? Additionally, my understanding is that the V2s in the M-60s in the back have to be GTA/Bs to handle the voltage.

When does the bidding start on the Bad Boys?

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

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...

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).

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.

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.

Any experience with mullardtubes.com? I've seen them advertise here recently, but I've not heard them mentioned by any users, yet.

Is Blackburn the factory of choice for Mullard 12au7s?

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).

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.

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

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.

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.

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.

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.

My favorite is the 7316 sub for a 12AU7. I use them in my Jadis DA 60 but have rolled them into several different integrated amps with great outcomes. They are very good for upper end detail and have a soundstage that is unreal, in a good way. They are scarce and to my knowledge were only made around 1960 and only by Amperex Holland. The one caveat is that they can be very expensive these days. OTOH what good tube isn't? If you like the clarity of the Siemens for a strong clean signal try that other German tube Telefunken ECC82.
BTW as my old friend says quoting Kondo San nothing is unimportant. The 6SN7s do have an impact on the sound the Sylvania GTB IMHO are very nice somewhat warm tubes with a euphonic midrange. I won't write a novel about the available 6SN7s to try. They remain the only tube that is infinitely better as NOS or OS than anything new. Please note that I emphasize infinitely better. My own tube collection contains mainly older tubes. However new production has begun to climb up the lader as true NOS go extinct and pulls or throw away tubes are what appears to be what is being sold.