MC transformers - what do they sound like?

Thom. thaqnks for that, The Bent audio Mu transformers appeals to me as it is easy to change the loading and seems to have a good reputation.

What is the difference between changing the load on a MC transformer compared to changing the loads on an active gain stage. Most active gain stages have several impedance loading options these days.

there still seems to be no consensus on whether a MC transformer adds bass or takes it away.

My only expereince with MC transformers was with the Manley Steelhead and the transformers sounded a little more dynamics in the bass compared to the straight gain - sound wise not my cup of tea, a little hi fi sounding

Rwwear, I think you will find that ARC have dereleased their ref phono stage and replaced it with the PH7 phono. get / tube like the PH5 but souped up to the max.

the transformers sounded a little more dynamics in the bass

I think you'll find this is due to better loading -- rather than a characteristic of trannies at large.
What a well implemented tranny should offer is a little bit of extra signal purity...
Makris explains all of this above.
You can also consult Stevens & Billington's (S&B)site (link above, FLemke) for some implementation info.
Finally, experience I've with S&B trannies is very encouraging. I believe Bent uses these for their products.

When I had MC pickups I initially used a Signet transformer that was almost the size of a beer can, which I gather is larger than most. I was very skeptical about the merits of a transformer, and it was only after I abandoned it and went on to active MC preamps that I realized how good the transformer was.

This is probably an area where generalities are inapropriate. Results will be highly dependent on which transformer and which pickup is involved, and which preamp you compare it with.

Thom,

Brilliant post. Thank you very much for saving me alot of typing!

The Bent stepups are indeed excellent, though as Thom implied there is no one "best" trannie. Adjusting the reflected impedance on the secondary side (very easy with the Bent's) is vitally important, but even then you have the issue of the primary side impedance interacting with the cartridge. I suppose this is why (IME) some trannies work better than others with a particular cartridge even after reflected impedance is optimized.

As Thom also implied, using trannies well involves a lot of work. LOMC's are extremely sensitive to reflected secondary side impedance. Those who claim trannies have non-flat frequency response simply haven't done the necessary work.

We spent dozens of hours swapping cheap resistors. Finding the optimum value for a cartridge almost always requires doubling up resistors on each trannie. (This allows much finer gradation of resistance values.) Having done all that, we then spent hundreds of dollars on multiple sets of high quality resistors. I'll discuss those results in another post if anyone cares. The results with every cartridge were always an even frequency balance.

At ultimate performance levels, however, it is now my belief that a properly implemented gain stage will outplay any trannie. A transformer must, by its nature, diminish amplitudes and smooth waveforms. The effect in a good trannie may be very slight, but it cannot be eliminated. This means a diminishment of dynamics and a rounding of notes (bloat, in plain language). My new preamp/phono stage is built as Hi5harry described, FET followed by RIAA circuit followed by tubes. It easily outplays the Bent's and every other tranny I've heard. I have a friend who owns nearly 20 different stepups. He's used some of them for over 30 years. Once he got his new preamp (same as mine) they all went into the closet.

Beating the Bent's and Cotters takes a large outlay however. If you aren't able to spend $6K+ on a privately built preamp or $10K+ on a commercial one, the trannie route will often do a better job, provided you're willing to do the work.

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