Here comes detractor #1 Rob. I'm not a big fan of SUTs. I paid a small fortune to Michael Elliot to install a pair in my Counterpoint SA-5.1 that was heavily modified by Michael. I wanted to replace my Counterpoint SA-2 pre-preamp because even though I loved the sound of it, it was pure tube and noisy as a consequence. When I got my SA-5.1 back with the SUTs in it and played music, I freaked out because I did not like the changes they had wrought. They sucked the life out of my LPs. I had to send my SA-5.1 back to Michael and have him remove the SUTs.
Back in the days when I was a young man and was still visible to young women (once you reach a certain age, you become invisible to women who are younger than you and if you don't understand that yet, you will), I had a Denon MC cartridge that came with it's own SUT and I used it for a couple of years. I remember it being on the bright side of life, but it was the best I could afford at the time.
If you look at the FR of SUTs, you can see they are not flat. Some are better than others though like all things in life. Some SUTs have a tendency to ring at high frequencies which you may or may not hear as added brightness. The bottom line is there is no free lunch. Yes, transformers will step your voltage from your MC cartridge and they will do it very quietly. Does it have the 'life' of active gain though? Those who love passive devices will say yes.
For those who love tubes (and shame on you if you don't), the best of both worlds is to have a phono stage that uses JFETs as the first stage which then drives the tube stage. The JFET lifts/amplifies the signal out of the tube's noise floor before it reaches the tube stage. So now you can have a very low noise floor and still maintain tubes in your phono stage. That's where I will be heading back to. For the here and now I'm using a Krell KPE Reference phono stage which is of course pure SS and designed only for MC cartridges. And yes, it sounds damn good and it is quiet.
Mark my friend...and we're still friends:hey: we'll have to agree to dissagre. You can't base an opinion on one bad experience (Mike Elliot) unless you can tell me you tried literally dozens of phono front ends with SUTs. I haven't tried dozens but I've had a half dozen SUTs in my system over the last two years, all matched up with tube stages. In the same period i had several near-reference level SS phono stages incl your beloved Krell KPE, none of them even the Klyne I just sold brought the music to life in the same manner as SUT equipped tube stages have.
SUT's have the further advantage of being inherently balanced, I have a 5-pin XLR at my preamp's input that keeps the signal balanced from the headshell leads direct to the first tube stage - and its as quiet as the quietest SS phonostage ive owned (Whest PS.30R) As for FR curves, ringing etc, i can promise you I don't hear such things and relates to a miss-match of some sort, besides its of little to no consequence when its the SQ that matters most. lets face it, if measurements were all that mattered neither of us would be listening to tubes or analog.:bonkers: Just for kicks i've attached few pics from my a'gon ads, all these SS devices cant be good for the signal. My present phono stage has a xmfr, two tubes and maybe 20 other components per channel, max. how many does the Krell use, a hundred plus?
Paul-To answer your question about losing any of the tube magic by using JFETs in the front end, the answer is....yes and no. How's that for a simple answer? Seriously, I just don't think you can get away with running low output MC cartridges with a pure tube phono preamp unless you are willing to put up with a bunch of noise. I used to tolerate all kinds of noise and shrugged it off when I was younger but those days are gone. Now days I view noise as the devil that must be exorcised from your system. Anyone who was at RMAF this year and visited the Jeff Joseph room where he was demonstrating using vinyl with a VPI preamp that had a pure tube phono stage with lots of gain (I believe it was the TL5.5 Series II with 66dB of gain) heard what I heard, and that was lots of tube noise. It was so loud the guy in front of me asked Jeff if that was the preamp or the air conditioner making all of that racket. Jeff replied "both," and proceeded to turn off the air conditioner. It didn't matter though, the noise from the phono stage was still quite obvious and oppressive (to me).
It's just my opinion that if you want to use a LOMC cartridge and you don't like the sound of tube noise riding on your signal as you are trying to listen, you are better off going with a hybrid phono stage that uses JFETs and tubes like ARC and Doshi do as well as the Manley Chinook. I will also be reviewing the Hagerman Audio Labs Trumpet Reference phono stage and it too uses JFETs in the first stage. The Trumpet Reference was on display downstairs at RMAF in the room that sold LPs and I was mightily impressed when I saw the innards. This is one beautifully built preamp that uses premium parts. It has 4 big chokes in the power supply and a big, beefy power transformer. I'm stoked to hear this phono preamp in my system.
Rob-I wrote a response to you and somehow it disappeared. I think I became "unlogged in" and my post vanished in the bit bucket. You are absolutely correct that I don't have tons of experience listening to SUTs and people need to keep that in mind. I do have the latest Atma-Sphere MP-3 preamp winging my way for review and it does have SUTs in the phono stage. I'm anxious to hear it and it will give me another reference point.
if you can bypass the SUTs in the MP-3 and borrow a SS head amp like the hagerman, or better yet something like the Klyne SK2, I would be interested in your observations. My pre has separate phono inputs and the ability to bypass the internal SUT and try other SUTs or a head amp.
I've built preamps with both JFET and transformer step up and the consensus seems to be JFET (or high gain circuitry) for solid state and SUT for tube gear. The SUT is considerably quieter when used with tubes than an active SS gain stage and the synergy seems to be better. I use Lundahl transformers as a rule. These seem to have the best bandwidth and are very smooth through the audible range.
which Lundhal?