MC transformers - what do they sound like?

Hi Doug,

I would categorize the S&B in the very, very good category, but not in the world-class range of component. It continues to be my humble opinion that an extreme solution, whether it be a step-up or an active stage will be satisfying to the music lover.

Coming out of an after hours session at the Rocky Mountain Audiofest this October, the seeds of some very cool development in MC step-ups were planted. I have NO COMMERCIAL INTEREST in this project, but check out Dave Slagle's Intact Audio site (the forum) for ongoing discussions about what Dave is developing (http://www.intactaudio.com/).

In that Saturday night session, the likes of Frank Schröder, John Atwood (Artemis Labs), Dave, and others got together to play with step-ups.

Dave's first attempt nudged into second place behind Frank's unobtanium step-ups. For this experiment, Dave reached into his parts bag and pressed into service an autoformer volume control. In other words, it was an adhoc attempt, done on the fly, and not in the least sense of the word, a mature design.

In recent months, the boys in Fort Collins have been playing with dedicated MC step-up designs from Dave. These are the "boys from Colorado" referenced in various threads on Dave's forum. They have been playing with dedicated designs - trannies that surpass Frank's on a range of cartridges from Myabis to a Lyra Olympos.

There are some characteristics of step-ups which might be beneficial to musical reproduction.

One of them which comes to mind is bandwidth limitation. Note that trannies like the Jensens go out to 100KHz, so I'm not talking about premature HF roll-off. I suspect that some of that "juicy" sound inherent in good iron has to do with the filtration of RF Interference. This is speculation on my part.

Secondly, consider the moving coil cartridge. It's a motor assembly. The better cartridges have a reduced winding count (and the resultant output voltage) in order to minimize moving mass. Given a compatible transformer, what better way to effect gain than to "restore" some of the windings, but outside the cartridge so moving tip mass remains optimized ?

Thirdly, bass response is a function of the inductance of the trannie. It's definitely another one of those matching issues we've discussed.

Once again, it's my contention that there are multiple ways of solving a problem effectively, and the above thoughts are most definitely slanted toward my bias - in favor of trannies. I have no doubts that an extreme approach to active gain can also accomplish these ends.

Certainly, we're in agreement, that at real-world prices, MC step-ups rule.

Cheers,
Thom @ Galibier

Audio Note KSL-spx, - their step up Transformer - did anyone try it?

I can't compete on the technical descriptions, which are helpful by the way. In fact I have just changed from a good SS conventional phono stage, the Clearaudio reference, to a K&K phonostage. The lateral is a JFet/tube hybrid with Lundahl transformers. In the past I have tried Tom Evans and Trichord stages too. The K&K is head and shoulders above the rest, more detail, much more dynamic, much quieter, no better imaging, but every other parameter is better. Is that because transformers are intinsically better than active gain stages? I am sure it is because in this case, the K&K is a better thought out design.
At the risk of being obvious, are'nt you dealing with a set of compromises particular in good as opposed to the best gear. For most of us buying the good, it may not matter if the phonostage is active or with transformers, or the amp is SS or tubed, what matters is the skill of the design, which in turn depends on the balance of compromises made. There are still compromises with the "ultimate", design, such as the boulder. Perhaps its more interesting to discuss which way you would design the best stage you could build, at any cost, would that be active or transformer based? I don;t know the answer.

This is a very interesting thread. David12, you are right on the money. While for certain goals or design criteria, a certain design approach (step up vs gain) may be superior, its highly unlikely that any individual design does not involve compromise. Picking one design approach vs another is the easy part, based on your design criteria; effective implementation is the hard part if cost is a factor. I am looking forward to continued discussion on this, but mostly, I would love to hear a demonstration. One additional thought or question I would throw in the mix is this- are there certain upstream or downstream choices that affect the step up vs gain stage decision, all other factors being equal? I have no idea and look forward to comments from others.

>> I am looking forward to continued discussion on this, but mostly, I would love to hear a demonstration.

Open invitation to one and all! Hear it live! Bent Audio Mu's vs. one "no holds barred" FET gain stage.

Of course I defer to Thom's experience with better SUT's. If he'll ship me one we'll include them in the shootout and report. ;-)

I've also heard Frank Schroeder's unobtanium SUT's. They were certainly very good, but some other parts of the system were insufficiently transparent for me to note specific differences between them and the Bents.

>> ... are there certain upstream or downstream choices that affect the step up vs gain stage decision, all other factors being equal?

Great question. One thing that comes to mind is frequently balance. If a system or room happens to be tilted up or down at either end, it might be possible to compensate with SUT's by adjusting reflected impedance. I would never recommend such a "band-aid" approach, but it might work for someone who doesn't have the time, interest or resources to solve the problem directly.