Brauner Valvet

Dual-pattern Tube Capacitor Mic

Published in SOS March 2004
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Reviews : Microphone

Photos: Mark Ewing

I first came across the Brauner microphone marque about seven years ago. Dirk Brauner's company designed and built specialist valve-based audio equipment, as well as servicing a wide range of vintage pro-audio gear. However, Dirk's interest in microphones eventually lead to the production of the renowned VM1 valve microphone, and the range has subsequently been expanded to include several derivatives and variations — all but one employing valve-based head amps.

The model reviewed here — the Valvet — is closely related to the original VM1, but looks superficially identical to the only solid state model — the Phantom I reviewed back in SOS September 2002. The two mics borrow styling cues from the classic Neumann U47, and they both deliver a sound quality to match.

All of the Brauner microphones can be considered 'premium products' in terms of both their mechanical/sonic quality and UK price. However, more efficient production techniques have allowed the cost of the Valvet (and the Phantom, for that matter) to be reduced significantly in comparison with the original VM1. Although still hand assembled, the Valvet and Phantom mics use an internal circuit board rather than point-to-point wiring, and a Lundahl transformer instead of the bespoke twin-core design employed in the VM1.

The Valvet is shipped in a small metal case with strong plastic corners. This is lined with a dense foam to support the microphone (in its suspension cradle) and the power supply when in transit or storage. The cable and handbook are secreted behind a panel in the lid. The satin-nickel microphone body measures about 160mm in length, and its cylindrical body (which is as heavy as it looks!) is 50mm in diameter.

An eight-pin Tuchel (screw-locked DIN plug) connector is located in the base of the microphone to link with the supplied power and control unit via a bespoke low-capacitance cable roughly eight metres long. The Brauner logo, model name and serial number (615 for the review mic) are etched on the front of the body. The large one-inch capsule (the same as that employed in all the other models) is clearly visible behind the double-layer wire-mesh grille enclosing the top third of the mic.

The impedance converter circuitry is variously described in Brauner's literature as employing either a selected EF86 or EF732 valve. Both are pentodes and are used in an ultra-linear Class-A circuit configuration — a design that uses no overall negative feedback. Essentially, the output of the capsule is connected directly to the valve grid, and the valve's output signal drives the output Lundahl transformer.

For reference, the original VM1 used a Telefunken EF806 pentode, which is functionally equivalent to the EF86, but the latest literature suggests the EF732 is now used. This particular valve was one of the last to be designed, and is engineered to be soldered directly into a circuit, rather than plugged into a socket base — thus improving reliability significantly.

The front panel of the Valvet's power supply includes switches for phase inversion, polar pattern (cardioid or omni) and power, the latter with status LED. The front panel of the Valvet's power supply includes switches for phase inversion, polar pattern (cardioid or omni) and power, the latter with status LED. The front panel of the Valvet's power supply includes switches for phase inversion, polar pattern (cardioid or omni) and power, the latter with status LED.

Whereas the Phantom was equipped with toggle switches on the mic body itself, the Valvet is controlled from its power supply. The original VM1 had a continuously variable polar pattern and the Phantom had three switchable patterns (omni, cardioid and figure of eight), but the Valvet's power supply enables only two patterns to be selected via a front-panel toggle switch: omnidirectional and cardioid. A second toggle provides polarity inversion, and a third switch turns the power supply on and off (with an associated blue LED). The 10dB pre-attenuator included on the VM1 and Phantom is absent, but the healthy maximum SPL figure of 142dB for a very modest 0.3 percent distortion (the same as the Phantom) really obviates the need in most practical circumstances.

The rear panel of the compact power unit, which measures 51 x 115 x 200mm (hwd), carries an eight-pin Tuchel screw-lock female connector, a three-pin male XLR for the audio output, and an IEC mains inlet with integral fuse holder. The mains voltage is determined at the factory, with 230V or 115V versions shipped to the appropriate parts of the world.

A three-position toggle switch near the XLR output provides various earthing strategies. The 'H' position is a hard ground, connecting the XLR's pin one to the chassis earth. The 'L' position is a conventional earth-lift mode, allowing pin one to float completely isolated from the chassis. The third position, marked 'S', is a 'soft earth lift' which couples pin one to the chassis earth through a 0.1µF capacitor, providing a low-impedance path for audio, but very high DC resistance. The VM1 power supply is equipped with the same comprehensive earthing options, which really cater for all eventualities.

The supplied suspension cradle comprises pairs of 'C'-shaped metal brackets connected with metal rods. The inner cradle, which supports the microphone, is suspended from the outer cradle using six rubber 'O'-rings, and the arms have been designed to extend fractionally beyond the middle of the microphone's circumference. The ends of the rubber isolation rings looped around the connecting rods thus provide the required resilience to locate the microphone firmly and securely.

The outer cradle carries the stand adaptor, and a fairly long plastic lever arm makes it easy to adjust the mic's angle. This lever arm also doubles as a handy hook to loop the cable over to provide some mechanical decoupling — a useful facility, given the relative inflexibility of this particular multicore cable. A 3/8-inch thread adaptor is supplied for the 5/8-inch US-standard socket. This shockmount design is simple but ingenious, elegant, and absolutely typical of Brauner's engineering excellence.

The Valvet's technical specifications are very good for a valve microphone — as you would expect. The microphone's self noise is given as 11dBA which is only 2dB noisier than the far more expensive VM1. The mic's sensitivity is a generous 28mV/Pa and the frequency response extends between 20Hz and 28kHz — although no limits are given. It is interesting to note that the bandwidth of the impedance converter circuitry is given as 10Hz-150kHz.

Valve microphones require a little time to warm up, but I found the Valvet sounded pretty good within just a few minutes. Unlike many of the lower-priced valve mics, this one doesn't scream 'tube!' at you. Its thermionic character is subtle to the point of transparency, much like the classic high-end Neumanns. However, the Valvet shares the larger-than-life Brauner sound character — it may be physically smaller than the VM1, but it gives little away in sound quality. There is a full, rich sound at the bottom end, coupled to a clear, detailed top end — but there is no hint of peakiness or presence boosts. The sound is crisp and detailed, in the same way as a well-focused black and white photograph can be — the information is all there, and presented in a very natural way.

This mic has a fairly pronounced proximity effect when in cardioid mode — just like its siblings — and this needs to be taken into account when close-miking sources, to avoid an unnaturally heavy sound. As a matter of habit I always placed a pop shield in front of the Valvet, although a brief test suggested that the naked mic was not particularly prone to wind blasting. However, there were some very big 'thumps' when changing polar pattern, so it would be wise to close the fader for thirty seconds or so before auditioning the mic after changing pattern. The frequency responses of all large-diaphragm mics tend to vary considerably with the angle of incidence, but the Valvet exhibited a fairly smooth and progressive change, with negligible coloration over a typical range of working angles.

This is a lovely general-purpose microphone and, with specially matched stereo pairs being available, I can imagine it being used in spaced pairs and in Decca Tree configurations for classical recordings. Equally, the mic works very well for close-miking, and I found it especially revealing on percussive sources such as pianos, acoustic guitars, and both tuned and untuned conventional percussion.

The Valvet also performs admirably when tracking vocals. The mic captures every subtle nuance of the singer's voice — whether male or female — without the unnatural emphasis on the sibilance region that tends to afflict so many mics these days. Interestingly, though, during the extended period I have enjoyed with this mic its inherently detailed nature sometimes led to it being rejected in favour of an obviously less accurate mic. For example, there have been occasions where some vocalists (and one instrumentalist too) clearly benefited from a more flattering mic — one where a coloured and, dare I say, slightly 'veiled' sound delivered a more palatable rendition. This is not a criticism of the Valvet in any way — if the performer can deliver the musical goods this mic will capture them in perfect detail. But a less-than-perfect source will be revealed in all honesty, and that may not be what you really want!

The Valvet provides much of the exemplary performance of the high-end VM1 flagship valve mic at a far more accessible UK price, while retaining the top-notch hand-built engineering associated with the Brauner marque. If considering the purchase of a serious valve mic, it would be foolish not to audition the Valvet, which, in my opinion, compares very favourably with all of the obvious competition, regardless of price.