Townshend Audio Allegri Autotransformer Preamplifier

This is one of those reviews that was a long time coming. Not long after I reviewed the excellent Music First Audio passive magnetic preamplifier, I got a call from Townshend Audio asking (somewhat arrogantly, I thought at the time) if I’d care to ‘have a go on’ the same technology ‘done right’. The Allegri preamplifier is the result. Well, it’s not really a preamplifier; like the MFA Baby Reference before it, it lacks the gain stages that most people use to define a preamp.

The Townshend Allegri is actually classed as an ‘Autotransformer Preamplifier’; an autotransformer is materially different from a standard transformer (which has entirely separate windings between input and output) in that it takes a single winding with 24 discrete output taps. This means there is always an electrical connection between input and output, and as a consequence means the Allegri is intrinsically impedance matched between source and power amp, and signal attenuation properties of traditional ‘pot in a box’ passives are entirely averted. 

Those who judge their preamplifiers by weight and component count alone are duty-bound to be disappointed by the Allegri, however. It’s not a big box, and opening it up shows what’s mostly inside is air. There’s a terminal block PCB at one end, with separate left and right channel attenuator blocks and a source selector/muting PCB at the other. Between these is a bus cable. The fact that there isn’t a lot more you could put in a passive ‘autoformer’ circuit that wasn’t there for effect isn’t going to win many arguments here. I suspect neither is the point that many of the individual components (especially the dozens of metres of Townshend’s proprietary ‘Fractal-Wire’ and the extremely thin metal laminations that go into the autoformers) are custom made at great expense. For that group, the Allegri is simply a no-no.

In fact, you could argue the autoformers in the Allegri are designed as the right size for audio purposes. There’s a Goldilocks point here; use too large an autoformer and you have a power transformer, but use too small a unit and you have a filter. This might not sit comfortably with those who want an amplifier to be big and heavy, because the net result is an audio-frequency autoformer that is not much bigger than a couple of beer bottle-tops stacked together. But, other audio enthusiasts are more enlightened, and are prepared to listen to how something sounds over the sound of argument.

And it’s here where there was a bit of a revelation for me. Actually, make that two revelations; one sonic, the other philosophical. The navel gazing one was a mechanical understanding of the preamplifier. We sometimes think of it as the control room of the audio system, allocating the correct source to be output, and controlling the amount of gain fed to the power amplifier. That’s right by function, but wrong by execution. Instead, think of a preamplifier as the gearbox of the system, matching the drive of the source with the demands of the power amp. Suddenly, I began to get why there are so few good preamps and just a lot of OK preamps; too many focus on the controller aspect of the device, but forget that it has to dynamically balance the output of the source and the input of the power amplifier, while stepping the output drive up or down according to the conditions imposed by the driver, er, listener. It’s a gross oversimplification neatly skipping over engine size, tuning, bodyshell, suspension, brakes, handling, and practically everything else, but the difference between an air-cooled flat four in the back of an early Porsche 912 and an air-cooled flat four in the back of a VW Beetle was magnified by the gearboxes of both. One was precise, with close ratios, and put as much power as possible to the wheels at any time, and the other was a VW Beetle. The same thing, for surprisingly similar reasons (but without the cogs) applies to the preamplifier.

The big revelation though was the sound quality. It was the sound of nothing getting in the way. And the important part of that was within a few bars, you realised that practically all the products you’ve heard that make that claim (and the products about which you have made that claim) are the sound of ‘almost’ nothing. There is nothing here; it’s like direct injecting the sound of your CD player or DAC into your amplifier, only without the brief shriek of loudspeaker cones dying.

In some ways, the Allegri works backwards to most preamplifiers. Whereas in most preamplifiers, the sweet spot (where it sounds at its best) is somewhere in the middle of its volume track, the Allegri works to a pure inverse-square transformer function, where you get four times the drive if you halve the voltage, this is a preamplifier that actually gets better at low listening levels, thanks to improved low impedance. This doesn’t mean it sounds bad at higher listening levels, just that it extends its performance down into low-level listening, which is the place where most preamplifiers stumble.

How this all manifests in sound is the very model of ‘unforced’ presentation. The odd part is you end up defining the Allegri by the limitations of other products. Put simply, it makes them sound arch. Obviously, given the lack of active electronics, it has a silent background, but you realise how silent by listening to other preamps and saying the word ‘uncanny’ about the Allegri. Stereo separation is first rate, and doesn’t fall into the trap of imposing its own sense of image size to the sound; what’s on the disc is what gets out of the loudspeakers. If it’s a wall of sound recording, it will sound like a wall of sound. If it’s a carefully preserved recording of an unamplified instrument in a live space, that’s what you get. If you move from disc to disc, you hear the change in recording environments, but this isn’t the kind of device that draws your attention to that sound, thus giving you a dose of audiophilia nervosa. You just sit and listen to your music, enrapt.

The closest the Allegri gets to imposing any kind of character on the sound is still omission not commission. There’s a refinement that stays the right side of sweetness that can be heard on some of the very best active gain stages. This is extremely nuanced, and I’m struggling to define this, because it’s so rare and the Allegri gets so close, but where the Allegri presents the music intact, a handful of really top-notch preamplifiers have an ability to bring out the sense of musical intent behind the recording. ‘Sweetness’ is about as near as I can get here, but this is wrong. It’s not ‘sweetness’, because those rivals are not sweet sounding (and the Allegri is not acerbic by contrast). This is the kind of thing that really doesn’t translate in print, because the vocabulary doesn’t doesn’t reach to the desired level of subtlety and you end up writing more pretentious-sounding purple prose than usual in an industry that is well versed in pretence. But, if you put this against the very best (and the nearest ‘very best’ in price terms is probably the Berning preamp), and you’ll hear in that very best something no more natural, but possibly a little more inviting. 

OK, so there are limits imposed by the Allegri itself. The selection of cables, sources, and power amp becomes more important; especially the cable, as you could think of the Allegri as a few dozen extra metres of cable between source and amplifier. This selection process is not the usual passive requirement of having the shortest possible cables to prevent losses, however. The choices of device and cable are not necessarily limited or governed by the preamplifier (as they might have been with conventional passive controllers), but they are influenced by the nature of the design. If you have a source component with atypically low output voltage or impedance, or a power amplifier with atypically high input impedance, an active preamplifier is going to sound more dynamic. You can run very long lengths of interconnect with the Allegri, although I’d avoid extremely capacitive cables. However, the words ‘atypically’ and ‘extremely’ are pivotal here; the kind of equipment that would unseat the Allegri is the kind of equipment that would be hard to match into any system. And when it comes to cable, it’s hard not to consider Townshend’s Allegri without considering lengths of the excellent Fractal Wire on the outside to match that on the inside.

Highly recommended? Hell, things like the Townshend Allegri don’t come along that often. If you like music, you will like the Allegri. It’s that simple.

Technical Specifications

Type: Autotransformer line preamplifier.

Analogue inputs: Six pairs of single-ended inputs (via RCA jacks).

Analogue outputs: Two pairs of single-ended outputs (via RCA jacks.

Frequency Response: 8Hz-100kHz ±0.1dB.

Maximum signal level: 4V RMS (8Hz); 10V RMS (20Hz)

Maximum DC offset: 5mV (for undistorted 8Hz)

Impedance: Load dependant

Dimensions (HxWxD): 45x127x305mm

Weight: 1.5kg

Price: £1,895

Manufactured by: Townshend Audio

URL: www.townshendaudio.com

Tel: +44(0) 208 979 2155