Peavey Valvex

Paul White tries out Peavey's new rackmount mixer to find out if the tubes really make a difference...

The concept behind the Peavey Valvex is simple — so simple, in fact, that had this been a solid‑state mixer, most of you would probably have dismissed it as being too basic to be taken seriously. Occupying a modest 1U of rack space, and using just four 12AX7 tubes, the mains‑powered Valvex provides control over just gain and pan, plus a single post‑fade Aux Send. There's no EQ at all, and the only routing facility is a mute switch for each channel, which kills the Aux Send as well as the channel signal. In order to conserve panel space, the Aux and Pan controls share a dual‑concentric pot.

The Master section is equally straightforward, with separate Master Level controls for the left and right outputs, and a further two Level controls for the left and right Aux Returns. All the audio connections are provided on unbalanced jacks, and to maintain compatibility with as many input sources as possible, the input impedance of all the channels, including the Aux Returns, is around 1MΩ. In practical terms, this means that the mixer will accept all conventional line‑level sources, such as electronic instruments, tape and disc players, and so on, but also electric guitars, basses and even high‑impedance microphones.

Despite being a tube product, the level of hiss and hum is comparable with that of a solid‑state product, and, on paper, comes in at better than 85dB below the nominal signal level over a 20Hz to 20kHz range. The output impedance isn't specified accurately, but it is implied that any load placed on the output should have a 47kΩ impedance or higher (47kΩ is the usual professional line input impedance, but some less professional products have input impedances as low as 10kΩ, in which case the output signal level may be compromised slightly).

The Acid Test

Obviously, nobody is going to spend serious money on such a basic mixer unless it sounds pretty good, so it seemed logical to try it out with as many sources as possible. Compared directly with a well‑known, high‑quality solid state mixer, using CD source material, it was immediately evident that the Valvex had a 'sound'. Most people associate tubes with warmth, and nobody could accuse the Valvex of sounding cold. What you notice most is the top end, which sounds subtly bright and open — the nearest thing I can compare it to is a hint of enhancer. This doesn't surprise me, as enhancers work by adding harmonically related distortion to the top end of the processed signal by means of cunningly‑designed solid‑state circuitry, and tubes do more or less the same thing without being asked (unless you apply bags of negative feedback to linearise the response). In the case of this design, the tubes are run with a full HT voltage of something like 280V (according to my ageing meter), and there's no solid‑state circuitry in the signal path at all. Subjectively, the result of the tube circuitry is to make the sound more involving, more detailed and more transparent, but at the same time, it still sounds natural.

Tested with clean electric guitar, the result was less dramatic, and, to be honest, there was little to choose between the Valvex and a good DI box. However, synth sounds benefit from the Valvex sound, especially those with complex harmonic structures.

So, who will find the Valvex most useful? Well, if you're into quality multitrack recording, and, like me, you tend to avoid using EQ, then you might want to mix the outputs from your 8‑track, or even selected outputs from a larger machine using the Valvex. Alternatively, in a mainly MIDI studio, the Valvex could be used to enhance selected keyboard sounds and vocals. Direct outputs fitted to the six channels would have allowed the mixer to double as a multi‑channel DI box, so I feel there's a missed opportunity there, but in all other respects, the box performs admirably, and does exactly what it sets out to do.