Listening #154

To paraphrase the playwright Alan Bennett: When I started Listener magazine, my idea was to create a small, anarchist journal. But people wouldn't obey the rules.

In 2003, when I began writing for Stereophile, I felt very much at home. John Atkinson had one set of rules (footnote 1) to ring us in, us being the codependent communities of audio reviewers and audio manufacturers. Martinet that I am, I layered atop those policies a few rules of my own, to govern interactions with members of the industry. More recently, I began to observe an additional practice—I wouldn't quite call it a policy—meant to prevent mismatches, missteps, misunderstandings, and hard feelings all around: When someone offers me a product of a sort for which I have a consistent and automatic dislike, I tell them so. I say, politely, that I'm disinclined to borrow and write about the thing, because I suspect it will mesh with neither my system nor my tastes.

Even then, the supplier may persist. Recently, I was approached by the genial Harry O'Sullivan, of the Bespoke Audio Company (footnote 2): a designer and maker of evidently high-quality passive preamplifiers (footnote 3). O'Sullivan, whom I'd met in Munich, at the 2014 High End show, hoped I might review one of his products. Yet my prior experiences with passive preamps—which, by definition, lack active electronics, and thus confer on the input signal no voltage gain whatsoever—had left me underwhelmed: Although the best such products bring to the sound of a sympathetic system an extra measure of transparency, they have also seemed to leach from my recordings a measure of musical drive. The latter being more important to me than the former, passive preamps are rare visitors to my home.

My interest was piqued by transformers
Harry O'Sullivan and his business partner, Lucy Gastall, have owned and operated the Bespoke Audio Company since 2013. O'Sullivan also runs a small recording studio, and plays guitar in a couple of different bands; Gastall collects antiques, competes in a rally-prepped 1959 Austin A35, and works part-time at a haberdashery. Both cut their teeth working at Music First Audio, in East Sussex, England: also a manufacturer of passive preamplifiers, also a staunch believer in the suitability, to their products, of hand-wound transformers. In MFA's view, the use of a transformer with multiple output taps is the best non-active approach to signal attenuation, because it offers the opportunity for impedance matching and is far less likely than a resistor or potentiometer to add noise or coloration. Further, because it comprises separate primary and secondary coils, a multi-tapped transformer offers noise rejection as well as the ability to isolate a circuit from ground—this in contrast to an autoformer, which is a single, continuous coil.

Because O'Sullivan used to work in sound reinforcement, he knows a thing or two about impedance matching and noise rejection and the appropriateness of transformers to those tasks. Because Gastall used to make transformers for MFA, she knows a thing or two about what technical qualities separate the good 'uns from the bad 'uns. So when it came time for them to leave MFA, each independently of the other, they met up and began tossing around ideas for a company that would design and manufacturer fuel-injection systems for light-duty agricultural tillers.

Just kidding: O'Sullivan and Gastall decided to start making their own transformer-based passive preamplifiers. Theirs is an original idea—a genuinely bespoke passive preamplifier, the connections and cosmetics and other elements of which are selected by the hobbyist for whom it is made—and, as I can now attest, theirs is a well-made product, perhaps peerlessly so in its category.

The Bespoke Audio preamplifier ($12,000 in its most basic form, with price subject to currency-exchange rates) measures 12" wide by 4.5" high by 13.5" deep, and weighs a chunkarific 31 lbs. Its beautifully machined aluminum alloy casework is available in natural (silver), black nickel, or champagne gold finishes; those options also apply to the preamp's removable top plate, which the user can also have made from burr veneer, clear Perspex acrylic—indeed, the entire case can be made of Perspex, if one desires—or quilted ostrich leather (footnote 4).

Other elements that can be finished to the buyer's liking include a pair of decorative metal rings set into the top plate, corresponding with the positions of the two cylindrical transformer covers within; those transformer covers themselves (which, should the buyer choose the Perspex lid, will be eminently visible); decorative rings around the front-mounted volume and source-selection control knobs; and the knobs themselves. Many of those elements can also be engraved. Consider the ring around the source-selection knob: In the preamp's default form, the names of the sources engraved thereon are "One, Two, Three..."; they can also be made to read "CD, Tuner, Phono Preamp..." or "Good, Better, Best..." or "Flopsy, Mopsy, Cotton-tail...," the limits to one's choices being merely orthographic.

Common to all Bespoke preamps are a six-position source-selection switch and a stepped volume control, the 67.5dB range of the latter divided into 46 discrete positions. The volume control is motorized, for operation via a somewhat smaller-than-average remote handset, built into an alloy case. (Remote control requires use of an outboard power supply—a wall wart—included in the price.) The preamp's rear panel can be equipped with jacks for one to six inputs, and with one or two outputs; those jacks can be RCAs or XLRs—because the Bespoke Audio preamplifier uses transformers, it can easily convert signals from single-ended to balanced, and vice versa—in any combination the buyer wishes. Tucked away on the bottom plate is a miniature toggle switch that allows the user to lift the audio circuitry above the chassis ground.

A review sample was sent
My review loaner stopped here on its way to Koby Koranteng, of the New Jersey shop HiFi Logic: Rather than assigning a US distributor, Bespoke Audio intends to establish a number of retailers where prospective customers can hear and see the product prior to ordering from the factory—and HiFi Logic is the first of these. Freed from its sturdy, foam-lined flight case, the Bespoke preamplifier appeared impenetrable, as if its heavy enclosure were held together with magnets or some high-tech adhesive. Still, out of curiosities professional and personal, I wanted to have a look inside, so I asked Harry O'Sullivan how to go about it. Easily done: "We wanted the lid to be removable because we wanted the internal appearance to reflect what we hope is a beautiful exterior—an idea we got from beautiful watches."

O'Sullivan explained that, during the week before a Bespoke preamp is dispatched, he mails to the new owner the "key" to a single, large-headed bolt at the center of the bottom plate. In typical Bespoke fashion, the bolt is finished in the same color chosen for the preamp's accent rings, and the key is engraved with the customer's name—"as a sneak preview, to whet the appetite," in the words of O'Sullivan, who conceded that a large, flat-bladed screwdriver works just as well. I was impressed that this 3.5"-long, rubber-gasketed bolt, which fastens to a tapped opening on the inner surface of the precisely machined top plate, was beautifully finished, spotlessly clean, and fit with a degree of precision that could only be termed luxurious. A luxurious bolt, I tell you!

That wasn't the only thing that impressed me about the Bespoke, whose build quality is unsurpassed in my experience of all things audio. The case's panels are held together with stainless-steel machine screws and interior corner braces, the panels machined in such a way that the braces are nearly invisible. Machined into the inner surface of the bottom plate—the preamp's floor, so to speak—are two curved recesses designed to accommodate the bundles of wires that exit the bottoms of the shielded transformer cases, those cases themselves machined with Bespoke's unambiguously classy logo.

Footnote 1: This in contrast to those magazines whose reviewing policies appear limited to "Obtain signed advertising contract before committing review to print." Click here for a complete list of our rules.

Footnote 2: The Bespoke Audio Company, Hastings, England, UK. Tel: (44) (0)1424-756471. Web:

Footnote 3: Allow me to pause and acknowledge the distress felt by those who object, on technical grounds, to the term passive preamplifier. But because we assume the term to be well understood by 99% of our readers, I will carry on.

Footnote 4: I made up the one about quilted ostrich, though I'm sure O'Sullivan and Gastall would do it for you if you really wanted it.


doak's picture

Built my 1st resistive passive in 1985 and have used, primarily, no-gain controls of various types since then. It's been transformer/autoformer/magnetic controllers for the last 15+ years.

Not nearly every system is a good candidate for a passive controller. It is best that the system is constructed bottom up and top down to make best use of and accommodate the passive controller. This is very important and cannot be overstated. Will not go into detail here, but each component choice plays its part.

Also, I must add: IMO there is no reason any passive controller should cost $12K+. I expect the performance of the item under review can be equaled by units readily available for 10% of its price - if one can forgo the jewelry aspect of one's purchase.

adrianwu's picture

I played around with magnetic volume controls about 15 years ago, first with the Sowter units, and then with Stevens and Billington. The problem is to do with impedance, as the input and output impedance changes whenever the turns ratio changes. That means the frequency response might change as one listens using different volume levels. This is more of a problem if one is using it to drive transistor equipments, which typically have lower input impedance. The lack of drive Art refers to could also be due to losses that occur (hysteresis loss, wire resistance etc.) in the transformer. These problems are inherent to the transformer design and really could not be totally resolved. If one can get away from the purist ideology and build a buffer stage behind the transformer (for example, a cathode follower), this would solve some of these problems as it would present the load with a low fixed output impedance, and the source would see a reasonably high input impedance even when one is listening to a higher volume (lower signal attenuation). In fact, most line-level preamps have very little gain and is essentially a volume control followed by a buffer. I don't see any advantage in using transformers over a stepped attenuator approach using a ladder resistor network.

Pryso's picture

Art, interesting review, as always. Years ago an audio buddy built a few passive boxes to experiment with resistance values in the volume pot. Once he found which worked best in his system he gave me the (unneeded) 50K unit. I found that simple (2 inputs, switch, volume pot, 1 pair outputs) passive did in fact provide very good clarity and definition, but lacked in dynamics and musical drive. Since then it has been useful as a tool to judge the degree of "colorations" imposted by any active preamps/line stages I've auditioned.

However I have a broader question on your review. If, at the time it was written, there was only one US dealer where the BAC unit could be auditioned, how did that meet the rules you referenced in your introduction for a minimum of five US dealers for review publication?