MC3 step-up transformer

Listener, Summer 1998

Primary Colors
by Art Dudley

Here’s a list of everything that has broken around here in just the last couple of months: the cold-start valve on my car’s fuel injection system; the carburetor on our little gas-powered tiller; our VCR’s eject button (and with John Sayles, Henry Jaglom, and Jane Campion still making films, that could be its most important button of all); the water pump on our four-year-old GE Potscrubber 970 dishwasher; and my electric orbital sander. The refrigerator is starting to act up, too.

Now here’s a list of everything that can break in a moving-coil step-up transformer:

Note that this is under normal use. I suppose that if you throw a step-up transformer at a moving car, you might possibly break it. Otherwise, you’re safe.

I was about to say that a moving-coil transformer has no moving parts. But even the old-timers will tell you that that isn’t so - a point I’ll get to, but not right now.

First, the basics: If you want to listen to LP records, you need more than just a line-level preamplifier. If you’re running a moving-magnet phono cartridge-which has a lower output voltage than your CD player, tape machine, or tuner-you need at least 15 or 20 dB more gain to boost that cartridge’s output. Plus you need an equalization circuit to correct for the RIAA that’s imposed on all music recordings when they’re mastered for LP.

If you’re using a moving-coil cartridge, most of which have significantly lower voltage output than the average moving-magnet cartridge, you’ll need even more gain.

There are lots of ways to do all that. In the old days, when vinyl was king and I had all my hair, virtually every preamp or integrated amp on the market had phono inputs, with the necessary equalization and at least enough gain for moving-magnet cartridges. And throughout the 1980s, many such components boasted enough boost for moving-coils, too.

Nowadays, that isn’t so: You might have to contend with a preamp or integrated that has no phono provisions at all-and so you’re likely to want a single, simple box that provides both the EQ and all the extra gain you’ll need for any kind of cartridge: a phono preamplifier, aka pre-preamp.

Just as likely is this scenario: You already own or are about to buy a preamp or integrated amp that has phono inputs, with RIAA equalization and enough gain for moving-magnet cartridges - but not enough for moving-coils.

If that’s you, you can still buy a separate phono preamplifier if you want to, and hook it up to one of your line inputs. And if you choose to do so, there are lots of fine phono preamp choices out there - and a couple of superb ones, as well, like the Pass Aleph Ono and the Linn Linto.

But you have another choice as well: You can buy a product designed solely to boost your moving-coil cartridge’s output voltage for use by your existing phono inputs. And that can be done passively, with a moving-coil step-up transformer.

When we think of transformers in audio, we usually think of the big power transformers in our amplifiers - that or the output transformers in our tube amps, which are used to help high-voltage output tubes drive current-hungry loudspeakers. But transformers can be used for lots of other important jobs in audio, limited only by the designer's imagination and an observation of one simple rule:

A transformer can't just boost something. Rather, it can only take a ratio between two electrical characteristics in a circuit and invert it. And even then, there will be some losses, albeit extremely slight ones.

What I described two paragraphs ago is a fairly common thing: A transformer can begin with a relationship in which voltage is high but current is low, and invert it: At the other side, you will have lower voltage but higher current.

And to do this it needs only a magnetically permeable core (nickel is common, but there are lots of others) and some coils of wire-two coils in its most basic guise: the input, or primary coil, and the output, or secondary coil.

Now: What you have in the case of a moving-coil cartridge is a device with very low voltage output (I said that already, didn't I?) but surprisingly high current, by comparison. Moving-coil cartridges are in fact prodigious current sources for their size.

But we don't need that much current. What we do need, in order for a phono signal to be amplified and not be swamped by a component's residual hum, is voltage. A transformer can make this swap pretty well.

And an extremely good transformer can do this extremely well.

What makes one transformer better than another? You'll hear as many answers as there are transformer enthusiasts. But here are some obvious ones: Wire material. Wire size. Type of varnish or insulation on the wire. Turns ratio. The interleaving pattern of the wire. The core material. Core size. Core configuration.

The less obvious/more controversial characteristics include wire shape (what kind of die was it extruded or drawn through), chassis material, and the whole question of whether a transformer should be potted or not-which is to say, dipped in wax or epoxy or some such goo to prevent the coils of wire from vibrating.

Yes - vibrating. This really happens! The coils of wire in a transformer move, or at least they try to, just like an old-fashioned electrical buzzer. (A special note to you ladies: Depending on how you look at it, either a vibrator is a poorly made transformer, or a transformer is a very well made vibrator. Either way, perhaps this means you’re more of a techie than you thought you were.)

Step-up transformers add one requirement of their own to the mess: Given the delicacy of the signal they carry, they must incorporate some kind of shielding to prevent audible hum. The most common solution is to seal each individual transformer in a little metal can. (A stereo step-up transformer is actually two transformers, of course - one for each channel.) Some people take the idea further and insert mu-metal screens between some of the coil interleavings, then connect them to ground.

The theoretical advantages of a step-up transformer are many, the most obvious being the absence of active devices (tubes or transistors) and the associated parts needed for a working, linear gain circuit. All these things add distortion, ringing, and, depending on how they’re used, phase shift. Of course, a transformer can do all those bad things as well, but unless it’s very poorly designed or made, it will do so to a much lesser extent-owing as much to its simplicity as to anything else.

There’s another interesting difference in how a cartridge performs with a transformer: With a phono preamp, in order for the output of the cartridge to drive the gain stage, it must see an impedance that’s several times higher than the cartridge’s own internal impedance; without such a load, work can’t be done efficiently. With a transformer, the situation is different: Here, the cartridge wants a load that’s much closer to its own impedance.

In most step-tip transformers with multiple primaries, the coils are wound for different input impedances (the longer the coil, the higher the impedance), and these provide differing amounts of voltage gain, as well, with lower impedance primaries providing the most gain. This works out fine in most instances, because high-output moving-coil cartridges achieve their additional output with additional turns of coil wire, giving them a higher internal impedance-and making for a good match with the highest impedance inputs of such variable-input step-up transformers.

Is a transformer purer - and purer sounding? A lot of people think so. The signal is certainly traveling through fewer parts and in some instances less mass on its way from the record to your ears when you use a transformer instead of another gain stage or amplification device. Yes, it’s traveling through a fair amount of wire, but when said wire is configured as a transformer, the signal doesn’t quite "see" it the same way as when it’s laid out straight, with no flux lines cutting across it.

When might you want to consider a step-up transformer?

Over the past year that I’ve been playing with them, I’ve had very nice results using transformers in tube systems. When I use, say, Naim amplification (solid-state), I usually go back to their own very good Prefix phono preamplifier, straight into a line-level input - and that seems to complement the Naim strengths the best. The same may well be true of the other solid-state specialists who also know a thing or two about phonography - including Pass Labs, Exposure, and Linn.

But there’s something about the transformer approach that complements tubes in general, and the single-ended scene in particular. The best transformer match-ups I’ve had seem to let the music sing or flow a little bit better - and for the system as a whole to achieve that nice sense of breathing in-and-out that transistors, whatever their other strengths, tend to miss. Perhaps that’s because transformers let the user achieve a sort of symmetry: At each end of the chain is a moving-coil transducer, transformer-matched to a voltage amplifier.

In any event, I hope to work my way through all the serious step-up transformers I can find, one at a time. We’ll start with the very pretty E.A.R. transformer under review here, and work our way through various choices from Audio Note, Quicksilver, Immedia, and hopefully two or three others. (I know at least one transformer expert who’s considering entering the moving-coil step-up market, but who doesn’t want to go public quite yet; meantime, I’ll continue to push him in that direction.)

E.A.R. is a company founded by designer Tim de Paravicini in the 1970s. Tim, who rivals Arni Balgalvis and Jeff Rowland as one of the tallest men in hi-fi, is as well known for his professional recording work as for his home hi-fi products, recent examples of which have included some new ideas in single-ended amplification. A tube specialist, he has applied his genius - not too strong a word in his case, I think - to everything from studio tape recorders to a new loudspeaker design, and a careful look at the albums in your collection may well turn up his name amongst the liner-note credits more than once or twice. (The last time I saw Tim, he had just come from doing a bit of work at Paul McCartney’s place - so his credentials are certainly in order.)

The E.A.R. MC3, which Tim designed, does in fact contain two separate transformers, wound cylindrically and scaled in metal canisters. Each one has three primaries, providing input impedance choices of 4, 12, and 40 Ohms, and these are addressed by three separate pairs of gold-plated input jacks. Those three sets of inputs correspond with voltage gains of x30, x20, and x10, respectively, making the MC3 appropriate for use with an unusually wide range of cartridge outputs. The back panel features not one but two grounding posts, and these are isolated from the signal grounds with a pair of 10-Ohm resistors.

The chassis is chunky and very attractive. The parts (not much more than jacks, really) are fine, and build quality is good but not perfect (a couple of those solder joints look kind of gloopy to me). Silicone seal has been applied liberally around the transformers themselves, presumably for damping.

I used the MC3 with my regular Lyra Lydian cartridge, the internal impedance of which is 2 ohms, and the new Miyabi cartridge, whose coils measure 4 Ohms. In both cases, I did in fact have the best results going into the transformer’s lowest impedance/highest gain inputs. I sent the MC3s output to the phono inputs of my Fi preamplifier.

Among the first things I noticed about the MC3 is its very wide bandwidth, especially as compared with other transformers. (I have since learned that E.A.R. claims an effective bandwidth of over 10Hz to 100kHz, and based on what I’ve heard there’s no reason to doubt that.) Among other things, this manifests itself in a pretty, shining clarity on such things as massed violins and brass. Regardless of style or instrumentation, in fact, music making is very explicit through this transformer: All the details in the score and the nuances of playing arc easy to hear, understand, and enjoy - but then, nothing’s thrust out or spat at you.

The E.A.R. is also free of audible grain. Timbrally, there are no problem areas or isolated bits of coloration, although I can understand how its extreme clarity and cleanness would make it appear light overall in some systems-and so, in such instances, it would probably work especially well with richer, "plummier" sounding cartridges.

Examples? On The Byrds’ "You Don’t Miss Your Water," the MC3 has the effect of "illuminating" the recording: It’s not made bright, though you probably wouldn’t want it any brighter than this. Percussion is really snappy, full of properly timed attack transients, and cymbals have realistic decay and "swoosh." Everything here is clean, articulate, and, again, explicit.

And for me, engaging. Maybe not the ultimate musical magic, but very entertaining for hi-fi. On Led Zeppelin’s "Since I’ve Been Loving You," the MC3 again sounded remarkably clean, with every bit of detail and texture well lit. I thought it was very involving and moving, if not quite the best I’ve heard - though I bet I know at least five people who would find the E.A.R.’s presentation the most involving of all the transformers I’ve heard so far. But on Peter, Paul, and Mary’s "All My Trials," I did in fact think the E.A.R.’s performance was the best, and most moving, that I’ve heard. My pancreas liked it, too.) Sonically, this was a winner as well: transparent sound, an almost magical presence to the voices, and even good spatial detail and scale.

While I was in folkie mode, I decided to give the first Leonard Cohen album a spin. (I know some of the songs are pretentious as hell, but the ones that work, REALLY work, and I’m on my third LP copy since my high school days, when Bob Shedlock first turned me on to it.) On "So Long, Marianne," Lenny’s voice was, again, palpable and real. Same with the background singers: Voices have tremendous ease and presence through the MC3. The electric bass was agile, and when the brushed snare drum entered at the end of the fourth verse, it had impact and the right spatial perspective, too.

The MC3’s clarity also helps keep all this recording’s trebly instruments distinct from one another: Cohen’s nylon string guitar, the electric guitar, and the mandolin all have their own unique characters here, not to mention musical lines.

How does it stand overall? So far, the E.A.R. is one of five currently manufactured step-up transformers with which I’m familiar. I don’t think it’s quite the very best of the bunch, but it isn’t far from it. (Incidentally, this is one product category in which musical quality and price seem to track one another pretty closely-so far, at least.)

I’m impressed with the MC3, and from a musical point of view, I think it’s worth every penny of the price. Those of you who have tube-based systems and can afford it should pester your local dealer until he lets you take one home and try it out. (I mean, what’s it gonna do - break?) Given a good record collection and a superior m-c cartridge, there’s a chance you won’t send it back.

Quality: ****-I/4
Value: **

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