2. amps-preamps
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Preamp for Aesthetix / Atma-sphere

Hi

I have the Aesthetix Io Eclipse with volume and dual power supplies, Atma-sphere MA-1 monoblocs (140 watts) and Audiokinesis Dream Maker (93 db sensitive) speakers. These are great components. My question is about system synergy, how to make them play together.

I have been running the Io direct to my amps since I first bought the Mk2 version back in 2004. At the time, I had a Krell FPB600, and in that context, it was a blessing, and a great step up from the Krell KAV 250p preamp. I'll never forget my first impression with the Io - it was like going from the wooded hills up into the mountains. There was no going back.

With volume, the Io functions as a preamp. It looks like a preamp. Someone here on A-gon said going direct is best - which I interpreted as: it IS a preamp! So I thought, OK I have a combined phono and preamp - problem fixed. But it wasn't.

From recent testing I have finally become convinced that the Io does benefit from a separarate preamp. Even if clarity and detail is better going direct from the Io to the amps, the punch and "here-ness" of the music is clearly better with a preamp in the chain, at least in my system.

Trouble is, which preamp? I am testing a small solid state Musical Innovation preamp, which helps with the punch but veils the music. An optimal solution might be the Aesthetix Callisto, preferably with dual power - but I don't have the space, and I already have a lot of tubes and tube heat. I have space for one or possibly two boxes.

From what I have heard so far, a solid state might do the job well (in my tube-rich context), however it should not impart any s-state artifacts or reduce the resolution from the Io Eclipse.

The ideal would be to test a few tube and s-state preamps, and then decide. However, this is difficult where I live, so advice is welcome.

My question relates to my own setup of course, but is relevant for everyone with a top phono stage on the one hand and amps on the other. What is best in the middle?

From recent testing I have learned that problems that I thought were related to the speakers, the phono pre, the pickup and so on, were in fact related to the preamp issue. For example, the Dream Makers straight from the Io may sound a bit lazy and washed out in the bass, very clear in mid and treble but not fully embodied. Plugging in the solid state pre, the situation becomes dramatically different, now the speakers are driving, propulsive. Very enjoyable, but some detail is lost and some transistor things added that I don't want.

So I am looking for a solution with most of the plusses, and not much of the minuses. The preamp must be fully balanced with XLR in / out.
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Ag insider logo xs@2xo_holter
atmasphere's avatar
atmasphere
11,849 posts
 
Not sure, is the RCA 12bh7 tube equal to other 12au7 variants, regarding gain?

The gain, or mu, is the same however the 12BH7 is based on the 6SN7 tooling. If you examine the 12AU7 you will see that it is a 6SN7 plate structure that has been sawed in half. The 12BH7 is the whole thing and IME a better sounding tube.

The filament specs are double that of the 12AU7- you might want to check with Einstein before using the tube in your preamp.
audiolabyrinth's avatar
audiolabyrinth
4,555 posts
 
Thankyou O_holter, great post, this will be interesting to see if the Telefunken's are as good as the Hytron tube, @ Atmasphere, wow!, you are saying that we may or may not can use a 12BH7 tube in place of the 12au7 tube, I believe that was information was of grave importance!, thanks, welcome back to the thread.
Ag insider logo xs@2x
o_holter OP
977 posts
 
Thanks Audiolabyrinth, I agree. Atmasphere, grateful for your warning note, I am checking with Einstein. Jafox noted earlier in the thread that the 12BH7 may work fine even if the specs are not quite right, but he does not say that he tried it in the Einstein.
audioquest4life
772 posts
 
Not sure if you heard about the German brand Octave. I had the HP500 SE for a while than sold that and purchased the Octave Jubilee preamp. Before I purchased the Octave Jubilee, I tested the Einstein preamp. Though it was good, and bass was articulate, I feel the Octave Jubilee is better due to its ability to create uncanny realism with music. I use a pair of Mcintosh MC2301 300 watt tube amps with the Jubilee. Previously, I had Octave MRE 130's which I used with all three preamps. The Einstein was better than the HP500 SE, however not the Jubilee.
Good luck
Audioquest4life
Ag insider logo xs@2x
o_holter OP
977 posts
 
Two days ago I got the RCA 12BH7A black plates. Wow! Best so far. The sound stage is larger, more bass especially. This really engages the room, I can hear it from the next room (kitchen) too. I’ve never heard Pink Floyd: Pulse (the LP box) this good, with such a great “being there” factor. Or the (incredibly ambitious) first Ambrosia LP. "Nice, nice, very nice" - indeed!

I have checked with Einstein, will I be OK using a 12bh7 in the 12au7 position, but the answer wasn’t quite clear, so I’ve asked again. However I hear nothing wrong and the trafo temperature seems about the same.

So for now, using Io Eclipse as source and the pair of Siemens Halske 6922s in the phono inputs of the Einstein, the RCA 12BH7A moves to the top of my list, even better than the CBS Hytron. Both of these sound better in the 12au7 position than the Telefunken (needs more break-in) and the stock Sylvania green label 5963. So thanks to Jafox (and Atmasphere) for bringing the 12bh7 into the discussion. The gain seems to be about the same, with the RCA / CBS / Tele / Sylvania I have tried (no change of the volume control) - but the music *feels* larger and more present with the RCA.

An interesting effect of this discussion is that I have stopped worrying about (1) was it the right preamp and (2) is it too solid-state sounding. Instead I am enjoying it a lot - the tube investigation is exciting. This preamp really changes personality, so when people write, “I heard the Tube but preferred preamp X”, I am wondering what tubes were in the Einstein.

Audioquest4life – I would love to hear an Octave Jubilee one day. I have read many of your comments, very helpful and informative, in this forum. Are you still using the Io Signature as input to your preamp?
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