MC phono stage without transformer?

Clio,

I believe Dave Slagle is supplying the new magnetics for the Bent. I've been using Dave's autoformer volume controls for a while now, and they are extremely good.

-Richard

Rccc,

I don't get how it is best to avoid load resistors but apparently ok to use a zobel that adds both resistance and capacitance? Seems counter-intuitive to me. Or, are we talking about the pre-amp side?

As Atmasphere pointed out, there are certain inherent limitations of transformers. But, that is true of ANY means used to amply the signal of a low output MC cartridge. If an additional active stage is needed, that too, has its problems. Unlike a transformer, any active stage will increase noise. It is easier to control noise with solid state devices, but, solid state has a particular sonic signature that some may prefer to avoid.

My own preference is for tube-based phono stages. However, that usually means an extra stage of amplification over an MM phonostage or the use of a transformer. Part of the problem with transformers is that they need to be carefully matched to the particular cartridge to work their best.

The other "problem" is that really good transformers are NOT CHEAP. I've heard great sound from Audionote (uk) and Kondo stages that had breathtakingly expensive transformers in them. I heard homemade units with the Audionote transformers that were also terrific. Another transformer that sounded good to me is the Jensen. My own phono stage (Viva Fono) has a transformer in it, but I don't recall its provenance.

Palasr,

The Slagle autoformers are being used for the TVC.

A post from John on his Audio Circle forum regarding the step-up transformers:

"Finally I have a new transformer I am happy with. It's a unit wound by Magnequest that we worked on together over a good part of the past year. We tried quite a few options and this one really stood out from the rest and it felt good to land on something like that! Just now getting the shielding can's on order and arranging a production run with Magnequest so it'll be the end of June or so before I get the stuff needed to make the first production run.

Pricing should be the same as before - or very close. The 1:10 / 1:20 gain switch will be standard now."

He had a couple at VSAC so he is probably very close to full production.

Ralph is absolutely correct in that transformers have their problems. Designing one that gracefully hides their limitations is quite the challenge, with some of the main contenders being Lundahl, Bent (Slagle), Jensen, Tribute, Audio Note, et. al.

Now, designing a phono stage capable of accepting a .25mv cartridge and producing musical output is not a trivial affair either, and Atmasphere, Nick Doshi, and Essential are some of the main contenders in this arena.

I've heard entrants from both camps produce very musical results.

A while ago, I did a bypass test with a pair of Lundahl step-ups (LL 9206) into my full-function Quicksilver preamp. The Quicksilver is MM-only capable with total gain (including line stage) being 58 dB. The good news is that it is extremely quiet, and the gain structure of the rest of my system permits me to get reasonable volume when fed by my Dynavector XV-1s.

Running the Lundahl, there was the slightest bit of audible smearing, but all in all, it was remarkably close to running straight in to the Quicksilver which is a very revealing phono/pre.

Some MC capable phono stages have separate MM inputs. You would be advised to try this test yourself if you have access to one. Run a step-up into the MM stage and compare it against running straight into the MC stage.

For the price of the Lundahal (while not perfect, it is faithful to the music), you'll learn quite a bit about what may or may not work in your system context.

Also note that Jim Hagerman makes a solid-state head amp, which I believe is called the Piccolo. It's another option for those with MM-only phono stages. I've yet to try one, so I can't comment on it.

The problem you will face is in auditioning in your current system context. You may well find yourself preferring one architecture over the other, only to discover later (with an equipment swap), that your results change 180 degrees. This isn't the first time you've heard this, but in the case of analog, the number of variables you're dealing with make the analysis exponentially more difficult to sort through.

Cheers,
Thom @ Galibier