The BPM Studio Technik TB-94 is the latest in a wave of heavy-duty valve mics that don't cost a king's ransom. Steven Streeter finds that its talents are concentrated in a particular field of instrument recording...

Those of us fortunate enough to have access to a quality microphone often take for granted just how painless and stress free this solitary device can make one's life behind the console. A touch of compression, some proximity filtering, and away you go.

Over the years, high quality electric condenser mics such as the Neumann U87 have become immensely popular with professional studios, being cheaper, generally more reliable and (in a technical sense at least) offering better performance than their valve counterparts.

While nobody would deny the limitations imposed on valve transducers by the laws of physics, few who have heard an old Telefunken, for example, could fail to be impressed by their beguiling, inherently smooth tone, particularly in the midband.

Background

BPM Studio Technik are a company based in West Berlin, and are a relative newcomer to the British consumer, bringing their range of mics to our shores through Small World Distribution.

Weighing in at around £1200 is the TB-94, a valve mic that comes complete with a substantial flight case, shockproof mount, power supply and all relevant leads, to get you up and running the minute you get home.

Once out of the case, the first thing I noticed was the rather inferior rubber bands used on the cradle mount to suspend the main body. I feared the worst when setting up, and was vindicated in my apprehension when, lo and behold... it snapped upon removal of the mic. This kind of flimsy mount suspension is clearly not acceptable on a mic at this price, and I sincerely hope BPM Studio Technik will take steps to address the problem.

Cradle aside, the overall build quality is impressive. I suppose if you're going to cut costs anywhere, the mount is the least likely to have an adverse effect on sound quality. There are two switches on the substantial body; the first is a three position switch which actuates a -10dB pad and high pass filter, while the second switches between cardioid and omni-directional modes.

"The manufacturers claim that plenty of low noise gain is available, and you had better believe it!"

After warming up the valves for a few hours, I proceeded with a few basic tests to establish any serious flaws in frequency response.

No major abnormalities reared their heads, and the mic produced reasonable LF extension, albeit with a mild peak around 250Hz that produced a slight boom, particularly noticeable with male vocals. The only other minor hiccup was a rising response - above 2kHz, not drastic, but enough to hint at a bright, slightly forward overall presentation.

Bench tests

How would all this stack up when subjecting the TB-94 to a typical day's use? The first thing to hit you is its sheer loudness. The manufacturers claim that plenty of low noise gain is available, and you had better believe it. Fed straight into the mic amp of a DDA DCM232 desk alongside a U87 and U47, it attained a significantly higher output (by some 5dB) than both Neumanns, although the noise floor even at unity gain with the U87 was a little higher.

I had suspected that due to the rising response above 2kHz, the TB-94 would be sympathetic to acoustic guitars, and so it proved, with the first obstacle thrown at it being a Gibson 7200. Gibson 7200s are intrinsically rich in tone, but have a recessed top end by some standards. However the Studio Technik's HF response brought out the sparkle, and gave the transient attack of the steel strings more impact than the comparatively dull U87. Ultimately this was at the expense of midband detail, the bass-heavy Gibson needing a tad more LF roll-off on the TB94 than the Neumann to prevent the sound becoming a touch muddy.

So, the thumbs up on acoustic guitars, but how would it fare against the Neumanns on vocals?

This proved to be something of a stumbling block for the TB-94. While achieving results comfortably above average, the real problem was the rising HF response, producing an annoying sibilance that made de-essing essential with the particular vocalist I was using. I would find this feature irritating to live with, to say the least. Aside from this, the Studio Technik turned in a fine performance, giving good projection and detail, while rejecting all but the gale force 'pops'.

"...it's worth a place in any studio's mic drawer for the spectacular results achieved with acoustic guitars"

In contrast to the TB-94, the U87 had no such problems with sibilance. While sounding comparatively dull, there was still an abundance of articulate treble detail and midrange clarity which ultimately gave it the edge on this occasion.

So to the piano, in this case a Yamaha grand. Once again, the valve mic stamped its strong sonic character all over the instrument, giving the grand a bright, well focused sound with the upper register sounding crisp and clean with an impressive sense of scale and dynamics.

Verdict

On the whole, the Studio Technik TB-94 showed itself to be a mixed bag. It didn't conform to typical valve mic values, in that its strength doesn't reside in an ability to produce exquisitely detailed or transparent midband. At the same time it sounded almost un-valve-like, with its pronounced treble and fairly deep bass.

Certainly in this case, its 'tailored' frequency response proved to be rather more subjective than Neumann mics, which gave consistent results throughout. Considering the price, it is not a mic that I would consider a great allrounder, but it's worth a place in any studio's mic drawer for the spectacular results achieved with acoustic guitars, and to a lesser extent pianos.

I also suspect that equally successful results could be achieved with woodwind and strings, although I had neither the time nor a handy string quartet to experiment.

At £1250 the TB-94 is not cheap, but considering the studio where I work recently sold a pair of thirty year-old Telefunken valve mics, in less than perfect nick, for nigh on £4000, it's not that excessive either. It certainly didn't disgrace itself in the tried and tested company of the comparatively priced Neumanns.

If you're in the market for a quality condenser mic, and have a grand burning a large hole in your pocket, you could do worse than invest in a BPM Studio Technik TB-94. I would, however, advocate careful auditioning before taking the plunge. Just make sure you have a plentiful supply of rubber bands for that dreadful mount...