The hand-held vocal mic has traditionally been almost exclusively the province of moving-coil designs, for the condenser mic, with its fragile diaphragm and built-in electronics, has generally been considered to be insufficiently rugged to withstand the rigours and abuse of stage use. In recent years, however, manufacturers have successfully confronted this problem, and there are now an increasing number of models on the market which combine the condenser's inherent advantages of extended frequency response and high sensitivity, with rugged, roadworthy design and construction.

Design

The Milab BM73 is a cardioid, condenser mic, intended principally for hand-held vocal use, but suited also to a variety of instrumental applications, both on-stage and in the studio. The long tubular body of this model widens just below the head, and is capped by a tough, steel mesh, domed grille, utilising two layers of wire and an additional foam screen in the area directly on-axis with the diaphragm of the condenser capsule. The extremely heavy-duty construction should certainly ensure a robust reliability but it also results in quite a substantial weight for a hand-held mic, although the design is actually well balanced and feels comfortable enough in the hand.

A fully recessed slide-switch is featured, located near the top of the mic, which introduces a degree of low frequency roll-off into the response. The output from the built-in FET pre-amplifier is low impedance (200 ohms), and balanced, via the integral three-pin male XLR connector (wired Pin 2 'hot', Pin 3 'cold', Pin 1 ground). Being a conventional condenser model, as opposed to a permanently polarized, or 'electret' design, the BM73 requires an external 'phantom' DC voltage source (applied equally to Pins 2 and 3, with Pin 1 as power supply negative), both to polarize the capacitor element and to power the pre-amplifier, with any voltage between 24v and 54v being specified as acceptable for this nominally 48 volt design.

The very wide specified frequency range, of 30Hz to 20kHz, rises continually, but smoothly, over almost the whole extent of the response, only beginning to decline about 15kHz. Very close-up usage extensively modifies the low frequency response, providing the expected degree of bass boost due to proximity effect, but the switchable electronic high-pass filter facility offers a rather more subtle and satisfactory action than most on-board response shaping switches, seeming to provide a shelving action that retains a reasonably extended response whilst maintaining control of the boosted bottom-end.

Uniform Response

The uniformity of the polar response of this model is a particularly impressive aspect of its performance, resulting in very good feedback rejection in PA usage, as well as the minimal off-axis colouration needed for use in demanding recording applications. The precise cardioid pick-up pattern gives the tightly controlled directionality that is so critical for stage work, with excellent front/rear discrimination being displayed at all frequencies.

The smooth, extended top-end that one expects of a good condenser mic, gives an open, transparent quality to the sound that facilitates very natural vocal and speech reproduction with a suitable PA system, whilst the rising midrange response always ensures good articulation and sufficient presence to cut through in a mix. In a side-by-side comparison with a popular and respected moving-coil hand-held vocal mic, the BM73 sounded significantly cleaner, smoother, and more controlled and extended at both ends of the frequency scale.

The freedom from any unpleasant colourations that this model seems to display also makes it well suited to miking up many different instruments for sound reinforcement purposes. Frontline acoustic instruments, such as brass or reeds, will benefit particularly from the use of such a high quality mic in this situation, for the successful amplification of such sounds, with any degree of fidelity, depends on accurately picking up their complex and extensive harmonic structure. A combination of high sensitivity and good upper frequency response produced particularly pleasing results on saxophone - an instrument whose sound is frequently 'strangled' by the use of rather moderate moving-coil models on PA.

Uses

In recording applications, the BM73 again proved to be a usefully versatile performer. On the drum kit, a powerful close-miked tom-tom sound can be achieved without having to work too hard, either on the kit or at the mixing desk, and an excellent crisp, tight, snare drum sound is produced by the mic's tilted response, especially when assisted by some lower midrange cut on the EQ, somewhere around 300 to 600Hz. The top-end on this model could even be considered sufficiently smooth to facilitate drum kit overhead use in some circumstances, for it produced reasonably clean sounding cymbals and hi-hat, and certainly conveyed the incisive quality of the drums, with plenty of stick impact being audible.

The extensive tailored midrange and 'presence region' response of most microphones designed mainly for hand-held vocal use, will normally cause poor results when used for recording any wide-range acoustic source. However, the BM73 sounds much more like a dedicated studio mic in this respect, giving a pleasingly bright, and relatively uncoloured sound on acoustic guitar, and the top end of an acoustic piano - both instruments which readily reveal any significant amount of midrange colouration in a mic.

The BM73 is specified as able to withstand up to 144dB SPL, making this model suitable for close-miking the very high acoustic output of small brass instruments. Indeed, its overall response seems to be quite well suited to this application, for it produces a clean, detailed sound, without the hard or brittle quality that a condenser mic can sometimes produce with these instruments.

One would expect the BM73 to perform well in the recording of vocals, and it certainly does not disappoint in this department. Whereas many stage vocal mics have a tendency to impose their own particular character onto a source, this model to some extent offers the alternative of a greater degree of neutrality, which leaves the engineer more able to make his own decision as to the optimum response tailoring. The BM73 is always sufficiently bright to give good definition and clarity to speech and vocals, whilst avoiding both any tendency to emphasise sibilance (the sound of the consonants 's' and 'c') and the rather fatiguing quality of an authentic presence-boosted microphone.

Features

Although not necessary for stage use, I found it advisable to employ the supplied foam windshield for close-up vocal recording, to be certain of avoiding problems with 'popping' on explosive breath sounds. The on-board 100Hz roll-off switch was also used in this application, and proved entirely successful in counteracting proximity effect.

Handling and impact noise is kept to a minimum by a surprisingly simple, yet remarkably effective, shock-mount system, which decouples the condenser capsule from the microphone body using a ring of compliant rubber. The subjectively more annoying high frequency content of cable and handling noise is well down in level, whilst floor and stand rumble, and other low frequency effects, are similarly well controlled.

The BM73's high sensitivity (-46dB/Pa at 1kHz, ref 1V) results in a substantial output level, and in some of the tested close-miked applications it was certainly felt to be advantageous to protect the mic amplifier with the mixing desk's 20dB attenuation pad, both to ensure freedom from the possibility of overload, and to achieve a reasonable range of adjustment on the gain control. However, it's probably reasonable to assume that a mic of this quality is unlikely to be used with equipment that lacks this facility. As anticipated, output noise was sufficiently low to be considered negligible under all normal circumstances of use.

Despite a growing popularity, the currently available range of condenser mics suited to frontline stage use is still not all that extensive. However, Milab's BM73 displays most effectively the particular qualities that a good condenser design can offer in this field. For a mic designed primarily for hand-held use to also perform well in so many recording applications must surely be considered something of a bonus. However, the BM73 would indeed make a most useful general purpose studio mic, for use in close or medium range work. Whilst its characteristic sound is certainly bright, I did not feel that it was lacking in warmth with any of the tested sources, and the rising response is certainly useful in necessitating less EQ when a 'toppy' sound is required.

This Milab model is supplied with some useful accessories: a robust dual-thread stand adaptor, a foam popshield, and a good quality, generously long (10 metre) XLR(F) to XLR(M) balanced microphone cable. Unfortunately, a foam-lined cardboard box provides the only protection for transportation and storage, which is a little disappointing when considerably lesser quality models invariably seem to include a rigid protective case.

Conclusions

The BM73 is priced at £180 exc VAT, which seems fairly reasonable for a high quality condenser mic, and with the all-round capabilities of this model taken into account, I feel that it makes an attractive and competitively priced proposition.

Although Milab may currently be an unfamiliar name to some, they offer an interesting and varied microphone range, including a well-engineered 'PZM'/Boundary Principle mic (reviewed HSR November 83), and a particularly nice, variable polar pattern studio condenser, designated DC63, which I have previously encountered and found to be an excellent unit. The refined, versatile performance of the review model can therefore only enhance the reputation of Milab microphones in all fields of sound recording, broadcasting, and live sound reinforcement.

Further details from: AVM/Ferrograph Ltd., (Contact Details).