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there don't seem to be that many 6SN7 preamps, while many employ 12AX7's and 12AU7's. Why? Is it harder to come up with a good circuit for 6SN7's, more expensive to design/implement? Less good 6SN7's available than 12AX(AU)7's? AFAIK there are hardly any phono sections that use 6SN7's. How come?
IIRC the only 6SN7 pre I've heard was a Cary SLP 98. It sounded pretty good to me, but not radically better or much more "big toned" than 12AX(AU)7 based pre's I've heard. I only heard the Cary for a short time at a show, so my impressions of it are not based on long term auditioning.
So what's the deal? Do 6SN7's really inherently provide more fleshed out timbre than 12's?
Follow Ups:
I can confidently confirm the tone of the de Havilland Ultraverve 3. Kara loves the 6sn7 tube. Teh Ultraverve deserves all the praise it receives and more!!
Antique Sound Lab Flora-EX DTBest preamp I've ever heard/owned.
Autoformer front end/attenuator.
2 X 6SN7 constant current gain stage.
Edits: 11/01/14 11/01/14
Didn't have a big tone but was slightly lean and very fast.
All octals & 4-pins, all the time...happiness :-p
Jim J.
Edits: 10/31/14
Back in around 1990 I was looking to upgrade from my Croft Super Micro preamp, and KJ West One in London suggested the Super Micro A, which came in an identical box to all the other Croft preamps, but was a more sophisticated design, including better regulation and more linear circuits. It turned out that there were two very different versions of the SMA, with one having SRPP circuits using ECC83 and ECC82 valves, and the other based on a simpler topology but using the octal valves 6SL7 (one per channel in the phono stage) and 6SN7 (one in the line stage, shared between channels).
After audition I decided on the SRPP version, as I felt at the time it was the more neutral-sounding, but I did enjoy the octal preamp - it had a lovely bold and rich sound.
The only octals I have in my system now are the Sylvania 6SL7 and 6SN7 in my differential 300B amps.
Alex
nt
DeHavilland Ultraverve 3.
Observe, before you think. Think before you open your yap. Act on the basis of experience.
I said empty .
If you don't become the ocean, you'll be seasick every day.
—Leonard Cohen
I've just started listening to a full Atma-Sphere rig -- incredible :-)
Vbr,
Sam
Ditto here. Atma MP-1 and MA-1's sound more like music than anything I have yet heard.
Yes.In my experience both at home with Cary and Mapletree gear, plus what I heard at a one-time local Cary dealer, I agree that 6SN7 gear has "big tone." I recently finished a rebuild of my Dynaco PAS, which is running the original Telefunken 12AX7s and is very, very sweet but still does not have the tone richness that my 6SN7 gear has. I met Dennis Had a few years ago at a dealer event, and he said that is why he likes the 6SN7, and I believe Kara Chaffee of deHavilland feels the same way. I’ve found quite a bit of variation in rolling different 6SN7s in terms of top-to-bottom balance and other things, but they all have big tone.
Edits: 10/29/14 10/29/14
Try a Cary SLP-05 with good NOS tubes...Big Tone, plus extension at the frequency extremes.
The humble SLP-98 comes with Chinese tubes from the factory; perhaps that's how you heard it. But I used to have the direct-coupled F1 version of that, and with some NOS Sylvanias or Tung-Sol round plates, it was quite respectable.
"Your liver suffers dearly now for youthful magic moments...so rock on completely with some brand new components"
...the Cary SLP-05 that I once owned used several 6SN7 and was the best sounding tube linestage I ever had. It was 'tubey' w/o the tube drawbacks. In other words, it was hugely dynamic, not wimpy polite like some, not at all rolled off with excellent bandwidth up and down the range, and it was transparent as in 'clear'.
I messed around quite a bit with tube rolling the Aesthetix Calypso which is also a nice tube linestage but not in the same league as the Cary SLP-05. Also had a couple 6H30 based ARC which don't sound much like tube linestages to me, not by my taste anyway.
Yeah, don't think I've heard anything but good reports about the SLP-05. If it was either cheaper or included a phono stage I might already own one. But even getting one used at prices I've seen on A'gon plus the cost of buying a good new phono stage would be more than I'd like to spend.
Gotta hear it one of these days just for the hell of it.
Long answer is the why of it but it has to do with linearity and lower microphonics.
You can get good bandwidth too- 200KHz to 400KHz is not that hard!
Exactly what a friend who built tons of tube gear over about 4 decades told me when I asked about the 12 AX7 vs the 6SN7. It's the more linear tube and I recall one evening when he and David Berning told me that linearity was the one characteristic that most correlated to good reproduction.
The 12ax7 has a lot more gain than the 6sn7.
The 12au7 is similar to the 6sn7 but the 6sn7 is way more linear (produces less harmonic distortion).
The 6sl7 has only a little less gain than the 12ax7.
As a preamp tube the 12au7 might be OK because a preamp will not ask the tube to swing much plate voltage (harmonic distortion produced by a tube goes up as the plate voltage swing goes up).
As a driver tube (to drive the output tube(s)) the 6sn7 is much better than a 12au7 because at higher plate voltage swings that will be required of a driver stage tube.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I've read the same comments about 6SN7s being great sounding tubes, but I only have one point of comparison. I've had my Cary SLP 98P (with phono) for a number of years and really like the sound. When I bought it I compared it back and forth against a CJ similarly priced preamp at a dealer. The CJ model used 12AX7s and 12AU7, not the 6SN7. Obviously I liked the Cary better as did my wife. Jumping to some quality NOS tubes recently has made a nice difference. The phono stage does in fact use a 12AX7 and 12AU7 per channel. I have upgraded those tubes as well, also worth that cost.
The upscale Cary 05 model uses 4 6SN7s per channel and that is a stunning preamp, beyond my wallet.
I'm not sure what the design or cost differences between the 6SN7 and a 12AX7 might drive, but you are right. Cary is in a minority that uses and seems to like the 6SN7. The SLP 98 is now about 15 years and running as a product offering for Cary and seems to still be a design that isn't "broke".
It's all in the implementation of the tube in the circuit as to what it sounds like. Design it right and it will perform well, screw up the design and bad sound is the result. Why more manufacturers don't use the 6SN7 is their choice.
Manufacturers that do use it - Cary, Rogue, Atmasphere, myself, to name a few.
BTW - 6SN7 does not have enough gain for a phono stage. It's cousin the 6SL7 should be used.
Dan Santoni
The Mystere ca21 preamp uses that tube and it does have big tone.this is an outstanding piece
nt
Read some of the comments on this site There area few reviews out there as well. Or just let your ears be your guide.
I've only had two 6SN7 based preamplifiers in my system, one from Cary and one from Rogue. Both were sub $2k units and both had great midrange tone but were rolled off at either end of the frequency range and were muddy sounding. I've heard much better preamplifiers in that price range using small signal tubes of various types. I also heard more expensive 6SN7 units from these manufacturers in friends' showroom that were better but didn't really impress me. This all was several years ago however.
This doesn't mean, of course, that a better designed, probably more expensive 6SN7 unit would have these drawbacks. In particular, I'd like to hear Rogue's 99 Super Magnum pre that my friend Paul Mah owns and reviewed in Stereo Times.
Sounded pretty good, but IIRC I wouldn't say the tone/timbre was better than old CJ pre's like mine or the pv11/12 that use 12AX/AU7's.
Dunno what *Super* means, the one I heard was just Magnum.
I liked several of the CJ pre's I've owned and heard a lot. They did have great tone and a refinement beyond most other units I've heard. I probably shouldn't have sold the Premier 17LS I had.
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