Until now, musicians wanting to add that distinctive valve sound to their recordings have had to beg, borrow, or steal to do it. At a mere £149, ART's new tube mic preamp looks set to change all that. Paul White checks it out.
Ahead of us we see the promise of an all‑digital future based on angular bits of silicon, DSP effects and tapeless recording, and yet a backward glance reveals the gentle curves of valves, their seductive glow beckoning us to sample their esoteric charms. Certainly the market in vintage, redesigned, refurbished, relaunched, repackaged and rediscovered valve gear is flourishing, but the cost is often unsettlingly high when compared to its solid‑state equivalent. It therefore comes as a pleasant surprise to find ART building a low‑cost valve mic preamp aimed at the home recording market.
Naturally, before trying out the preamp, the first step was to prise off the lid and take a look inside. As expected, the valve (in this case a 12AX7/ECC83 dual triode) is accompanied by a significant amount of solid circuitry, including a dual op‑amp and a handful of transistors, so I suspect that a low noise, solid‑state front end is being fed through a valve buffer stage biased to add a noticeable dose of valve coloration. This is fair enough, as it's not easy getting an all‑valve front end to run very quietly, even when you have a lot more money than this to throw at the design.
In common with a lot of budget valve equipment, the usual '250V DC plus' lethal high tension power supply has been replaced by a much lower voltage system, which does affect the valve's overload characteristics, as well as reducing the overall headroom, but if done properly, this approach can yield very pleasing results. In fact, the power comes from an external 9V AC supply, but I assume a voltage multiplier is being used somewhere, otherwise the maximum possible DC supply would be around 25 Volts, and the 48V phantom power switch on the front panel proclaims that this clearly isn't the case.
The tiny case for this preamp is based on the metalwork ART use for their budget MR1 reverb (reviewed in SOS February '95). There's just one input and one output channel, but these are paralleled on both balanced XLRs and TRS jacks, so you have a choice of what type of connector to use.
The usual mic preamp controls are provided, including input and output gain, but rather than provide the usual 60dB range of gain followed by a 20dB pad, the labels imply 40dB of gain with a switchable 20dB boost. Obviously, this amounts to the same thing insofar as the user is concerned, so I can't really see the reason for this break in tradition.
The other conventional control is a phase invert button, and aside from the dual‑colour LED which doubles as a power‑on indicator and a clip warning, that's pretty much what you get. A couple of slots in the top of the box provide a reassuring view of the glowing valve, and the steel case itself is finished in a robust black powder coating, which also helps radiate the heat generated by the valve heaters.
During my tests, the Tube MP turned out to be as quiet and vice‑free as an all solid‑state preamp. To test the noise, I put a large‑diaphragm capacitor mic at the end of a very long lead, turned up the gain, and monitored the result over headphones to prevent feedback. Though some noise was obviously evident at full gain (some of it attributable to the mic's own electronics) I could also hear the ticking of clocks from all over the house and the gurgle from the freezer's cooling system in the adjacent kitchen. Unless you're into recording things like mating woodlice, I don't feel that noise is going to be a major problem with this preamp, though to put it into perspective, most properly‑designed console mic amps facing this test would perform similarly.
Where the differences start to show is in the tonality. Tube circuits tend to introduce quite measurable amounts of even‑harmonic distortion, and this has the dual effect of adding definition to the top end, and thickening the bass. It's a well‑known fact amongst home music system designers that a little deliberate low‑frequency distortion makes the bass sound louder and punchier, but valves do it so nicely!
With very respectable capacitor mics coming right down in price, you can now get a sound at source that rivals that available from top‑end professional equipment. And with the addition of this very affordable tube preamp, you can go one step further and create your own valve mic sound, or plug in a regular DI box and 'tubify' it.
So, the good news is that the Tube MP works as specified and sounds nicely warm into the bargain, but as you know, I'm also paid to point out what I feel may be weaknesses in the products I review. The external power supply is obviously a nasty thing to have to live with, but I also feel that a high‑impedance DI input would have been easy to include for those wanting to DI guitars, basses, and brittle‑sounding synths. Those minor criticisms aside, ART's little preamp really works (especially on vocals), so if you only need to record one mic at a time and you really want to have your share of that tube magic, this has to be the most cost‑effective way of getting it.
- Respectable audio spec.
- Real tube flavouring.
- External PSU.
- A high‑impedance DI input would have been useful.
A welcome product that puts the valve sound within reach of virtually everyone.