Aurorasound SP-03H Step Up Transformer




I had this review written four months ago but I was procrastinating on submitting it, and I’m glad I did. While it was positive from the get go – and is even more so now – the original version read something like: “The Aurorasound SP-03H moving coil step-up transformer sounds great. It sounds really great. It sounds really, really great… but the damned thing just won’t stop humming!”

It took a while to solve the problem, but once I figured out what I had done wrong with its setup (careful cable choices are a must), I could simply and unreservedly report that this thing sounds great. No humming.

Now that I’ve given away my conclusion from this review, I’d still encourage you to read the additional 3000 words anyway.

An Embarrassment Of Phono Equipment

No question. 2017 was chock full of LP adventures. This assessment of the Aurorasound SP-03H moving coil step-up transformer is the fourth piece of phono-playback related equipment I’ve reviewed this year. The other three being two full phonostages plus my own Audio-Technica OC/9-III cartridge. Both of the phonostages were German-made but at disparate price points: one for the everyman and one definitely not for the everyman (though outstanding) and had enough features to control the space shuttle. The AT cartridge is, of course, the product of a venerable Japanese firm.

Aurorasound, also hails from Japan, albeit from a boutique manufacturer (boutique at least compared to AT’s wide and deep product lineup). The SP-03H brings a more refined, craftsman’s aesthetic and sensibility to the table, in addition to its fine sound, as I’ll discuss shortly.

Not every piece of equipment I worked with this year was new. In addition to doing reviews I also undertook a complete nut and bolt disassembly and restoration of an American made Rek-O-Kut T12h idler wheel broadcast turntable, which is now somewhere between sixty and seventy years old. Believe me: they don’t build them like this anymore. Every piece is cast aluminum with precisely drilled machine threads; the Elinco motor, which also has a cast aluminum case, is the size of a coffee can; the main bearing shaft is ¾” in diameter! All screwed back together it runs beautifully and will ultimately be the centerpiece of an improved monaural rig once I’ve finished the plinth, displacing my aged and battered Tech 12 Mark I.

Two tonearms also made their way into the house: a fifty-something year old Calrad SV-16 unipivot, an improved Japanese copy of a Gray Research 108; and a new magnesium unipivot from (of all places) the Ukraine, courtesy of Serge Karmadon, who appears to have started out performing restoration work before first developing his own clone of the aforementioned Gray 108, and then designing his own arm, which is what I have on hand. I’ve not heard either of these in action yet (pending the completion of the Rek-O-kut), but I’ve been staring at them on the sideboard for a couple of months while I’ve been working on the turntable and I’m excited about hearing them. And speaking of monaural playback, there’s that fancy Miyajima mono cartridge I just couldn’t leave behind at Capital Audiofest.

Now that I take stock of it, we’re busting at the seams with analog gear and I’ve rarely had as much fun with this hobby. I almost haven’t had time to listen to it all. I do have an actual job you know.

Systemic Change – State of The Art c. 1998

Tweekgeek2017.gifIt has been suggested that audiophiles are chronic late adopters of new technologies. A lot of us are still listening to LPs played through vacuum tubes, both of which were the ne plus ultra of musical reproduction in 1953, so there’s obviously some merit to that argument. Nevertheless, change can be good. To wit, a recent component swap brings my system contemporary with the death of Princess Diana, state-of-the-art circa 1998. We’re living on the edge here in Pittsburgh.

After some deliberation I swapped out my trusty Emotive Audio Poeta linestage in favor of the preamp that was designed and voiced with my Cary V12r power amplifier, the Cary SLP-98P. This particular unit has all of the Upscale Audio F1 modifications included. Most importantly it has an excellent moving magnet phonostage built in. The “98” designation, by the way, refers to the year it was introduced to the market.

Having added a second turntable for monaural playback, it’s just simpler to have at least one built-in phonostage (one less piece of equipment cluttering things up, one less set of cables to buy, etc.). Also, there really is something to the idea of system synergy between components that were designed together. As much as I loved the Poeta, and I would still highly recommend it, the SLP-98 is a better match with my amp.

I’ve put the SLP-98’s built-in phonostage to good use with my grungy Tech-12 and Ortofon 2M mono cartridge, which is musical if a little coarse compared to a good MC. This phonostage was no afterthought and is excellent in its own right. With my moving magnet cartridge, it’s been at least as good as any of the other phonostages that came through here, and in one case it embarrassed a pricey contender. Its obvious quality makes it useful as a baseline for comparisons with other equipment, and with two turntables in my system it eliminates the need for having either two separate phonostages or for having to find a phonostage with two inputs.  In general, the SLP-98 is a very fine sounding preamplifier, particularly with its matched components. Three cheers for 1998!


Tying it Back To The Review


Aside from the built in convenience, the MM phonostage pays another significant dividend. Rather than having to deploy a full stand-alone p-stage in order to use a low-output moving coil cartridge, a step up transformer (Herein after referred to as SUT) can simply be placed between the turntable and MM input on the preamp to provide enough gain to run moving coil cartridges, and in most circumstances do so for significantly less scratch than a high-quality stand-alone phonostage.

Functioning passively, all any SUT does is use a pair of transformers to boost voltage from a low output moving coil cartridge – in the case of my Audio-Technica OC9/III it’s about 0.4Mv – into a signal strong enough to be heard by a lower gain MM phonostage. The phonostage in my Cary SLP-98P has 43 dBs of gain, and the Aurorasound creates an additional 24, for a total of 67 dBs. That’s plenty of pickup for the OC/9 cartridge.

SUT’s offer one other potential advantage: As a passive devise they have no power source of their own, so theoretically they should be unsusceptible to AC line noise and therefore be very quiet. Unfortunately, based on my recent experience, and a good bit of reading up, SUTs also seem to be subject to a certain level of ground-loop hum and other artifacts if not carefully set up.

The only downside of SUTs is that there are also no fine adjustments for cartridge loading, but if the components are properly matched, the sounds meets with your approval, and you’re not a degenerate knob and switch twiddler you should be ok. After all, does anyone really enjoy messing around with banks of miniscule DIP switches? Of course not.


So, About The Aurorasound SP-03H Step Up Transformer

Tektonad.gifThe Aurorasound SP-03H, which costs $1,990, is about as simple as a piece of hi-fi equipment can get. Built around a pair of Lundahl transformers, it’s got two sets of inputs (one RCA and one XLR) and a single pair of RCA output jacks. It also has a finger nut to attach a ground wire. As a passive devise there is no additional power source, no on/off switch, no adjustments whatsoever, no power cords, and – blessedly – no goddamned IEC jacks: two in, two out, and the ground. That’s it.

All of these features are fitted to a brushed stainless steel top panel. The sides are finished in satiny rounded-over slabs of real black walnut with flawlessly mitered corners. Visually it manages to simultaneously look like a serious bit of tech while also creating the appearance of being carefully hand crafted. It was definitely assembled by someone who was paying close attention to what he or she was doing, and while it’s small and unobtrusive it’s also quite becoming.

Inside the guts are stuffed tight with natural cotton for damping. It weighs a grand total of six pounds and at about six inches squared it doesn’t take up much shelf space. Thirty seconds to hook it up and you’re playing music.


As I alluded to earlier, the SP-03H is – apparently like a fair number of SUTs – susceptible to negative electronic interactions with other components and cables. Alfred Kainz, the importer at High-End Electronics warned me not to place it near other transformers – say those in a pre or power amp – so I did a little re-arranging to make sure it was as far away from those units as I could get it given the cables I had at hand. I also spent a good bit of time ensuring that any cables connected to the SUT were not crossing the cables of any other sources, power cables, or each other. Using zip ties to hold all of the wires away from one another, the whole thing looks a bit ridiculous, but none of the cables are touching each other

Despite these efforts I did encounter some modest hum. I switched to more highly shielded cables, moved ground wires around, took the ground wires off altogether, re-arranged my power supplies, took out the sub-woofer, and a few other tweaks, but I could not eliminate it. With no signal playing the hum was audible from my chair, but just barely, and really couldn’t be detected once the music was flowing. This was frustrating, first because this is a fairly pricey piece of gear and it’s clearly not supposed to hum, and second because even with the low-level hum it was clear that the Aurosound SP-03H offered some fantastic sonic qualities.

Of course, since this SUT is a completely passive device I suspected user error, but for a couple of months as I wrote my original review, no matter what I tried, I could not eliminate the noise.

Then in early November I found myself at Capital Audiofest where I had the opportunity to discuss the hum issue with a few of the vinyl-centric vendors and they all said basically the same thing: an even more highly shielded cable between the SUT and phonostage would solve the problem. Somewhat conveniently each of them claimed – of course – that their cable would be the solution. It should come as no surprise that they were all anxious to sling cables at prices that ranged from merely outrageous to breathtakingly astronomical, but one fellow also let slip that AudioQuest cables tend to be well shielded for this particular purpose. As it happened, I have a couple of sets of AQ interconnects at home already, which also happened to be the only cables I hadn’t tried with the SP-03H, so instead of blowing scarce bread on another set of cables I resolved to try my own wires first.

Now these are not high-end AQ cables; they’re probably almost twenty years old (I think they were Copperheads. They’re green). But lo and behold, that guy was right. Installing the AQ cables between the SUT and the phono input on the Cary preamp absolutely did the trick. Whatever those cables are shielded with fixed the problem. The hum was vanquished and I am finally able to tell all of you what a fine sounding piece of equipment the Aurorasound SP-03H is with no reservation whatsoever. I knew it had to be user error.

By the way, the money that I didn’t spend on those stratospheric cables went into a far more interesting Miyajima monaural cartridge that I’ll talk about in a future review.

On To The Music

With that all sorted out I set about evaluating the SP-03H with some great music. By now I’ve listened to dozens of records through it, but here are three that stood out.

Headin.jpgMusic Matters’ 45 RPM pressing of Horace Parlan’s Heading South is as good a recording of a piano as Rudy Van Gelder ever did during the golden age of Blue Note Records. That piano still suffers from a bit of the instrumental shrinkage and pinpointing that was the byproduct of RVG’s close miking technique, but the sound is large and fully weighted, big, warm and harmonically rich. There’s even a little bit (and I mean a very little bit) of resonant air around the piano; a true rarity among RVG recordings.

Heading South is essentially a blues album, but oh, what blues! Parlan shows himself again and again as a sophisticated, thoughtful pianist, whether he’s showing off his dexterous fingerings, or blocking chords ala Red Garland, there isn’t a distasteful note on this album. Following George Tucker’s bowed bass intro on “Summertime,” from Porgy and Bess, Parlan’s lyrical, delicate touch brings some youthful jump to the performance. His playing is light-hearted and uplifting compared to the dirge-like way this tune often performed.

Through the SP-03H the overall sound has exceptional transparency, clarity and detail. It certainly isn’t adding or subtracting anything to the signal. Al Harewood’s ride cymbal positively shimmers like hot oil in a pan on the greasy Low Down. Treble extension is exemplary: smooth, detailed, and never harsh, as natural sounding a piano recording as ever recorded in Englewood Cliffs. Brilliant!

the three front web.jpgThe Japanese East Wind label’s direct-to-disc classic The Three, featuring Joe Sample on piano, Ray Brown on Bass and Shelly Manne on drums is an audiophile warhorse if ever there was one, but not without good reason. This was one of the first jazz albums I bought when I started collecting records again a decade ago (in the good old days when NM copies could be had for a fiver) and I’ve fairly worn this copy out, but even with a little surface noise the basics of this record are phenomenal. Manne’s hardest strikes on his trap have snap and great jump factor. The bass retains woody resonance all the way down, and the piano is by turns delicate and powerful.

Already an exceptionally transparent recording, the SP-03H made it even more so, doing exactly what we all hope every new component will do: give us more musical details per groove than we had before in a completely natural, compelling fashion.

With this SUT installed I’ve been favoring a lot of piano records. There’s a natural wholeness to the big keys that, with my system at least, conveys weight, scale, and dynamism properly. Delicate passages twinkle and shimmer and then change on a dime when full power is called for. The SP-03H makes the rest of my kit sound good!

gratefuldead.jpgA more recent acquisition is the Mobile Fidelity 45 rpm pressing of The Grateful Dead’s Workingman’s Dead, a record I’ve probably owned in one form or another – including cassette – since the early 1980s. This MoFi version is a long way away from the scruffy copy I had in eighth grade, that’s for sure. The soundstage is huge, in the way that 45 rpm pressings of LPs can do so well, and there are details like wood blocks and finger cymbals that I’d only ever heard as taps and jingles without actually being able to hear what was being tapped or jingled. It may not have translated to the original pressings, but Workingman’s Dead was a really well recorded album. This album is a lot of acoustic instruments supporting vocal harmonies and is possibly the Dead’s most folk inspired studio record. Half of these songs – Dire Wolf for example – could have been out-takes from an Alan Lomax field recording. The SP-03H takes all of those details and passes them unmolested straight into the phonostage in my preamp without loosing a thing. In thirty-five years of listening to it I’ve never heard Workingman’s Dead sound better.

This would be a good time to point out a specific truth about SUTs. They’re only ever going to be as good as the phonostage they’re plugged into. In my system the SP-03H handily vindicated my decision to add the Cary with it’s built in MM section by proving that that the Cary was fully capable of amplifying whatever came out of the SUT and making sure it still sounded great! It had sounded really good on it’s own amplifying the signal from my MM Ortofon 2M mono, but the Ortofon, while a decent basic cartridge, is not in the same league with a good moving coil; it simply can’t reproduce the same level of detail or refinement. You can’t have it all for $350 after all. Running the Audio-Technica OC/9-III – a far more sophisticated cartridge, if still not horribly expensive – into the same phonostage through the Aurorasound SP-03H made the whole thing really sing. I had some really expensive stand-alone phonostages in here this year and this setup – the Aurorasound SP-03H though the Cary SLP-98P – sounds as good as any of them.

On most records played through the SP-03H acoustic basses are deep and woody; massed strings are extended and never strident; and the midrange is as natural, liquid and fully realized as I’ve heard in my system. Truly, this diminutive little box is an impressive sounding piece of gear.

Picking Nits

So-far, so-good, right? Well I did find one sonic nit to pick but it’s one that has more to do with revealing the qualities of various recordings than anything inherently wrong with SP-03H.  As already stated, this SUT is highly transparent to the source, and in my system that meant – as it should – that I was hearing more of everything that’s on my records.

With twenty-four vacuum tubes in my amplification chain the SP-03H did something I didn’t think was even possible: it revealed some records that I’ve listened to for years with no complaint as being a little dry. This presented itself as truncated resonances: the wood of a bass was a little less woody than optimal, for example, or strings that sounded a bit hard. I didn’t yank any records of the table and smash them against the wall in disgust, but it was definitely audible, and something I’d rarely experienced in my system except on the very worst recordings.

An example would be something like Keith Jarrett’s Standards Live. It’s a crystalline recording (you can hear every one of Keith’s over-wrought vocalizations) but the piano sounds a bit metallic and sterile (at least to my ears) especially compared to a record like Duke’s Big Four, where the piano sounds so natural and weighty. Standards Live is still a great, well-recorded album, but the SP-03H is revealing enough to really point out those little nuances, and flaws.

I guess you could sum this issue up as doing something better than it was done before, but ironically achieving a lesser result, if only on a few recordings. On the other hand, with the SP-03H in place the truly great recordings – like all those mentioned elsewhere in this review – shone brighter than they ever had. Life is too short to listen to crappy records anyway.

The other thing that strikes me is that for a piece of gear using off-the-shelf transformers, in this case from Lundahl, $1,990 seems like a lot of money. After all, the internal wiring of an SUT is quite simple. Yes there’s a cost to build refined aesthetically pleasing casework, but I’m going to go out on a limb here and guess that this is a $1,500 box around $500 transformers. But in today’s hi-fi world that’s certainly not unique to this piece of equipment, and you could certainly spend a lot more money on an SUT or phonostage if you really wanted to.

Wrapping It All Up

I’m obviously impressed with what the Aurorasound SP-03H offered in my system: transparent dynamic sound, with that elusive midrange liquidity that we all seem to cherish. Sitting here listening to a humble mid 80s OJC copy of Sonny Rollins and the Contemporary Leaders I’m struck by how realistic the horn sounds, front and center between my speakers. It’s the kind of aural experience that audiophiles thrive on, the reproduction of a live performance over the simple reproduction of sound through some cheap mediocre devise. Go Sonny, Go!

This is the first SUT I’ve listened to in my system, so I obviously don’t have any comparative frame of reference to other units offering similar function, but that hasn’t stopped me from being able to hear really significant improvements in LP playback in my system. I can, and I did. The SP-03H may be a simple passive devise, but it allowed me to run a LOMC cartridge through the MM phonostage in my pre-amp with sophisticated aplomb: a first rate sounding piece of equipment.

Here’s how much I like the SP-03H in my system. After a good year of favoring vintage monaural records for their often more unified sound (at least over early stereo recordings), I’m going through my albums row by row, pulling our stereo records (some of which I haven’t listened to in years) just to see if the next one sounds as good as the last one and for the most part they do (crappy recordings will always sound crappy no matter what you play them through). My stereo SOTA is spinning hard while my monaural Tech-12 is sitting cold and idle, at least for a little while. The Aurorasound SP-03H moving coil step up transformer has been a truly profound improvement in my analog chain, one that I’m enjoying immensely.

Of course that Rek-O-Kut T12h, Karmadon arm and Miyajima monaural cartridge are waiting in the wings, so who knows what 2018 will bring. But for now, I’m just enjoying the music.


greg simmons 


Aurorasound SP-03H Price: $1,990.00

Input: Rhodium plated RCA or XLR input

Output: Rhodium plated RCA

Construction: Stainless steel and walnut

Transformers: Lundahl with amorphous cobalt core and oxide free copper wire

Cartridge Impedance (High): 15 – 100 Ohm

Output load impedance: MM input, 47 kOhm

Frequency Response: 10 Hz – 100 kHz +/- 1dB

Gain: 24 dB

Size: 183 x 175 x 75 cm

Weight: 1.6 kg 

US Importer: Alfred Kainz

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