An Analog Twist: Bob’s Devices 1131 Step Up Transformer Review

CT6A6049 Bob's Devices is a small operation run by one Bob Sattin, the man in the white lab coat with the words "Hear the Magic" embroidered in big red letters on the back. Maybe you've seen him at a local audio show? Bob makes and sells a variety of things on his website, but the thing you probably know him for are his little step-up transformers (SUT). Stereophile's Art Dudley wrote about Bob's SUTs a little while back, and was thoroughly pleased with the results -- the top-of-the-line model, featuring Cinemag 1131 transformers, is currently a Stereophile Class B ("borderline Class A") product, beaten out only by the legendary and 5x more expensive Auditorium SUT. More praise for the diminutive $1,195 SUT came from 10Audio, where it was given their highest award. This is some heady stuff. So, when the opportunity to try one out at chez moi came along at this year's Capital Audiofest, I tried not to drool too much on Bob -- and, with the unit in hand, I bolted before he could change his mind.


A quick step back. For those of you wondering what the hell a SUT actually is or does, let’s refer to Stereophile’s Art Dudley, audio wizard, for some guidance:

“A step-up transformer is a passive gain stage that works by swapping the high current and low voltage of a moving-coil phono cartridge for the high voltage and low current required by a phono preamplifier.”

I see you nodding, sagely. Yes, that makes sense. It begs the question of why you’d need to call attention to this aspect of a phono preamp design, so let’s just say this for that: there is more than one way to skin a cat. Which is still gross to say, in case you were wondering. What I mean is, when you need to boost a micro-volt signal to something your amplifier will be able to handle, you’ve got a problem to deal with. A big one. Huge one, actually. And that’s noise.

grinch-noise1This is that “free lunch” problem. Any noise that comes in early in an amplification chain tends to stay late and stink up the joint. There are a lot of ingenious ways of dealing with noise, and quite frankly, this is where all the innovation happens. It’s also why SUTs are interesting — they offer a way of boosting signal (of “stepping it up”) … without adding much in the way of noise. With an SUT, your phono preamplifier, then, can run at a much lower level of gain (assuming it has a moving-magnet/MM input) with an attendant lower noise. This has some obvious benefits, but one of the less obvious ones, at least according to Mr Dudley is this:

Virtually every MC cartridge I’ve tried has sounded better —more dramatic, more impactful, more nuanced, more colorful —when loaded with a step-up transformer, compared with being used to drive an active phono preamp alone.

Well, alrighty then. I’m going to take this at face value and use it as the justification that it is — an excuse to play with more gear. I mean, Art likes it, why not give it a shot? So, I did.


The Cinemag 1131 is a tiny thing. It’s about the size of a deck of cards. Well, two of them, sitting on top of each other. The one I have here has a black, glossy body, with a pair of silvery bead-blasted caps. There’s inputs, outputs (both RCA on this one, but you can get them with XLR ins/outs), a pair of switches and a grounding post. One toggle switch selects the gain ratios; you have a choice of 1:20 (26dB of gain) and 1:40 (32dB of gain). The other is a ground lift. And that’s about it. Remember, it’s fully passive, so there’s no power cord or wall-wart socket or whatever. The whole thing is not heavy — your audiophile-grade interconnects will likely lift it off the platform it’s sitting on if they’re not properly suspended. You’re going to need an extra set of interconnects (preferably shielded), of course, so don’t forget to factor that into whatever evil equation you’ve got going in your head.

My reference phono preamp is the TW Acustic Raven, made by Thöress; it’s a tube-design and it’s also MC-only. Which makes using an external SUT impossible. Happily, I had a phono preamp on hand to fiddle with — that is, one that was configurable for MM and MC. I figured, I’d run my sweet little Ortofon Windfeld (.25mV) into the MC input and then again, into the MM input fronted by the 1131. The only major difference between them, then, would be the extra cable and whatever was in the circuitry of the different paths in the phono preamp.

Pardon me while I wave my hands airily here, but it’s worth a word about the phono pre in question, the Phono-2-SB from LKV Research. This phono preamplifier is a two-box, solid-state, Class-A, zero-feedback design. It’s dual-mono end to end, and can accept both balanced and SE inputs and outputs. Or any combo of the two! I used it, here, single-ended to single-ended. Internal rocker switches let you set three levels of gain with input impedances set via jumpers, ranging from 50 ohms up to 47k. Very flexible!


Bob comes to town

One of the things I noticed, pretty much right away, was that the presentation was simply fuller. Part of this appeared to be something like a shift in the tonal center of gravity directly into meaty. With a 1:20 winding, I was able to nail the Windfeld right into the MM sweet spot (which is 5mV) for use with the 2-SB. This added 26dB of gain to the input of the 2-SB, who’s lowest gain setting was a 34dB, which gave me a combined 60dB, and All Was Right With The World.

I have to say that the 2-SB, by itself, sounds pretty wonderful — again, the full write up is forthcoming, so, consider this a teaser. The sound of the 2-SB, run directly in with the highest gain setting available (59dB, with the special-order “high-gain” version which adds 6dB to the base gain numbers), was very good — linear across the band, with no “smoothing” or noticeable grain. The best part was the absolute silence that this phono pre presented as a backdrop to the music. This is where you can insert all your favorite cliches that include the phrase “inky black”. Overall, the 2-SB seems to fall just to the warm-side of sonic neutrality with superior dynamics and detail retrieval. It is, in a word, excellent.

With the 1131 inline, none of that was tossed out the window. The 2-SB was still the 2-SB. But the sound of the overall presentation did change. Not enormously. Not “night and day”. It didn’t suddenly become a tubed phono pre, but it might have taken a step in that direction. Again, not huge. But … interesting. And yes, me likey.

I’ve been playing the latest from Nine Inch Nails, Yello and Depeche Mode, and the bass reach, tone, and overall speed of this combo is perhaps the best I’ve heard in this system from a vinyl front end. Again, a lot of this is a direct result of the 2-SB’s natural charms. The difference? Warmth. It might be that the 1131, with the extra link and extra cable, were just a hair noisier than the straight-through (not altogether surprising), but even so, what the 1131 seemed to do was hang more meat on the bones. Again, not a lot. But enough that it was noticeable, and the timbre of instruments sitting in the mid-range seemed more spot-on. Less “correct” and more “right”, if you will. 

Moving back up to my reference vinyl rig for a moment, I’ll confess that the bass is a bit loose with my Thöress inline, but I know it’s there and who cares, I like it. But when I compared it with the solid-state 2-SB phono, the difference in the down-low was stark. In fact, with the 1131 fronting the 2-SB, the bass was crushingly good. Again, the tone was fleshier. Definitely meaty meater-stein. Meat meat meat. Whew! I’m gonna have to go fire up the smoker after writing this all out. Anyway, with the 1131, there was also more bounce, more organic life to the music. Everything was better. Again, not a lot, but I heard the difference — and I preferred it. The only area I felt might have taken a step back was on the top end. A little sparkle, a little detail, seemed to be the trade-off here. If you “hear” my mental shrug here, there’s a reason — it wasn’t much. And, quite frankly, I suspect that this will vary cartridge to cartridge.

So, if I had to analogize … the 1131 was like … using Ghirardelli dark chocolate chips instead of Hershey’s Dark Chocolate in icing a devil’s food cake. Both work great, but the Ghirardelli dark chocolate chips are just subtly deeper in flavor.

Hmm. Is that too much?

How about this — it was like honey on a ham. I was really digging the 2-SB as it was, and with the 1131 SUT inline, the sound I was getting out of my whole vinyl front end was a salad of superlatives — with a side of bacon. I wallowed. Like bacon. I mean, like a pig. Wallowing. I like bacon. Or something. Salad of superlatives!

Whatever you do, you’ll need to be careful with cables, of course. I tried out some unshielded cables coming off the VPI Scout 1.1 turntable into the 1131 with another set from the 1131 into my phono pre, and the noise was unacceptable (see — who says “cables don’t matter”?). Bob sells some very nice silver cables for $795/pair that would do the overachiever a treat — I had a pair on trial, and they silenced the gremlins quite effectively, while still bringing forward all the audio goodies. I used this pair of cables for the rest of the listening trials.


SUT-ing your MC

I can’t speak to Art Dudley’s experiences with SUTs, nor to his wild enthusiasm for SUTs over other designs, but my fly-by with the Bob’s Devices unit does speak toward the possibilities of the approach. If you have a persnickety predilection for a warmer, fuller sound, I think a call to Bob might be in order.

The caveats here are the typical ones. This unit isn’t exactly a no-brainer upgrade, given the price. Quite frankly, most of us are sporting phono preamps (assuming we still have them) that fall below the asking price of this SUT, which would make this a non-starter of an upgrade — even if that price isn’t all that unusual or exorbitant for a pair of hand-wound high-quality transformers. When you start climbing the hill of audiophile pricing, you’ll have to wonder whether or not it’ll simply be easier and more cost-effective to simply buy a better phono preamp than invest in an external SUT and an extra set of cables. I can’t speak to that. But I will say that I personally prefer the sound of MC cartridges generally (there are exceptions, of course, including some truly superlative work from Soundsmith), and given that, I’m willing to trust Art and extrapolate that MC carts might sound better when run into a SUT instead of into a higher-gain MC input on a phono preamp. Maybe — stranger things have been known to happen, but no, I haven’t tried them all, so I can’t tell you anything with any level of definititudiness. But were I a betting man, and I had me a system I already liked, and my phono pre didn’t have an SUT and did have an MC as well as an MM input, then I’d be trying out the Bob’s Devices 1131. Quite a conditional there, but if that’s you, you should check it out. And if it is you, you know you will because as an audiophile, it’s pretty much a requirement that you tweak until your ears fall off.

All told, I think this is a really neat investment. Can’t recommend it unequivocally, given the narrow use-case, but I can and will say that I’m a fan and that I really like what it does with my MC cartridge.




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