Technology Showcase: Hanging Microphones
Jan 1, 2007 12:00 PM, By Bruce Borgerson
New suspended systems pick up better overhead sound.
Riddle: It's a piece of audio gear that everybody looks up to, yet it doesn't get much respect. What is it?
The answer, of course, is the “lowly” hanging microphone. Tucked up and away out of the spotlight and rarely touched, it tends to be forgotten. But this very isolation makes it particularly important to select the proper hanging microphone for the job.
To begin with, hanging microphones usually are the most difficult to either relocate or reorient. Often the hanging location is predetermined by a combination of aesthetics and application requirements. Essentially, it has to go where it has to go, within limits, and the microphone sensitivity, noise, and pickup pattern have to fit the given situation. Even simply re-aiming a hanging microphone can involve hazardous ladder duty.
Secondly, hanging microphones are almost always the most distant microphones from the sound source. Excellent sensitivity is paramount, therefore, as are low noise, flat frequency response, and a uniform pickup pattern.
Specific requirements will vary with the application. In this survey, we will be looking at microphones designed primarily for sound reinforcement in permanent installations. Miking the choir in a house of worship is by far the most common use, though other common uses are in theatrical productions, and in some concert applications for choirs or instrumental ensembles.
QUALIFICATIONS FOR ENTRY
The focus here is on overhead mono pickup from a defined area. Special suspended stereo microphone systems and techniques used primarily for broadcast or orchestral recording (X-Y, M-S, ORTF) are not included in the primary listings. To qualify for inclusion here, the microphone system must:
Be relatively small (around 0.5in. in diameter and, for cardioids, less than 2in. long)
Employ a highly sensitive electret condenser capsule
Have a long (20ft. minimum), thin cable for connecting the hanging capsule to a separate powering/preamp module, either in-line or wall/ceiling-mounted
Provide some method for aiming the capsule on the vertical axis while suspended.
Some microphones that could be used in the same applications but fall outside these restrictions are noted as “honorable mentions” at the end of the text.
The following text and charts are split into two sections with fuzzy boundaries: one for fixed capsule microphones, and another for modular systems. As a general rule (though there are exceptions), the modular systems offer higher performance, more options for preamp module placement (in-line or wall-ceiling plate), and a choice of colors.
All dedicated, one-piece systems have a cardioid pattern, while most modular systems offer hypercardioid and highly directional capsules variously known as supercardioid, line cardioid, or by some proprietary designation. For the sake of uniformity, these are called “line cardioid” or LC in the accompanying tables. Most modular systems also offer omni capsules, though their use in hanging applications is limited. Depending on how the manufacturer structures its ordering (“complete mic” or “à la carte”), an omni capsule may be a standard option or available only on special order.
SPECIALISTS AND GENERALISTS
The suppliers listed below also fall into two general categories: microphone specialists, and full-line companies that also market a broad range of other audio equipment. In the latter case, two or more companies may source their hanging microphones from the same OEM manufacturer, thus accounting for some striking similarities in both appearance and performance. And, finally, a caveat on specifications given here: All figures are as published by the manufacturers, but not all measurement standards and references are fully documented — particularly in regard to some models from the “full line” suppliers. Direct comparisons could be misleading: Skepticism and further investigation are advisable if specifications seem too good to be true for the price point. And, as noted above, flatness of the frequency response and uniformity of the pickup pattern are critical factors, and therefore invite close examination of the relevant curves and plots, when available. MSRPs are rounded to the nearest dollar, and most specifications to the nearest tenth of a unit.
For the sake of uniformity, sensitivity is given as mV/Pa; those microphones listing only the negative dB value (same reference level) were converted using the handy online tool at www.sengpielaudio.com. Maximum SPL values for all models surveyed fall between 120dB and 140dB SPL for 1 percent THD, which is sufficient for most common applications.
MODULAR HANGING SYSTEMS
Modular hanging systems allow more flexibility in selecting and changing pickup patterns by replacing the screw-in capsules. Although cardioid capsules are preferred for most installed applications, a narrower hypercardioid or line cardioid allows “spotlighting” portions of the stage or fudging on the sacred “3 to 1” rule if use of more microphones is desired.
The keystone element in the modular hanging microphone system from AKG of Austria is the HM 1000 hanging module ($225). Available in matte gray or white finishes, the HM 1000 mates with a selection of interchangeable cardioid (CK 31), omnidirectional (CK 32), hypercardioid (CK 33), and line cardioid (CK 80) capsules. The standard version comes with a 33ft. cable, with an alternate version (HM 10020) providing a 66ft. cable. Both mate via a mini-XLR connector and AKG's in-line DPA (Discreet Power Adapter), which accepts 9V to 52V phantom powering. A unique LED ring on the hanging module indicates that power is present, while a jumper inside the power module at the other end selects a low-frequency rolloff at 250Hz (-10dB at 50Hz). A flexible wire clip allows positioning at the desired angle.
Audio-Technica (A-T) of Japan takes the “Have it your way” approach to modular hanging microphones with two complete lines: the diminutive UniPoint models and the even smaller Engineered Sound series. Both lines are available in black or white and with powering modules as either in-line modules (XLR connector) or for wall/ceiling mount with screw terminals.
A-T's popular UniPoint series has been upgraded recently with a proprietary shielding system for greater RFI rejection. A switchable 18dB/octave rolloff filter cuts rumble below 80Hz. MSRPs for a complete UniPoint system start at $240 for the cardioid version (either color) with either the plate-mount or in-line module. Higher prices apply to the line cardioid capsule version with the same powering ($270), and to versions offering either battery or phantom powering ($290 to $320). Complete microphone systems are offered only with cardioid or line cardioid capsules; hypercardioid and omni capsules may be ordered separately. Attached cables are 25ft. long, and a nifty stand-mount holder with cord tube is included.
A-T's miniature ES series has a cardioid capsule less than 1in. long and 1/3in. in diameter, and even the 90-degree MicroLine in-line cardioid capsule is a mere 5.6in. long. Low-frequency rolloff is 12dB/octave at 80Hz, and the attached thin cable is 50ft. long. Complete microphone MSRPs start at $285 for cardioid with wall/ceiling plate mount and top out at $325 for the line cardioid with in-line module. Battery powering is not available in this series, and omni capsules are available only by separate special order.
The Audix ADX-40 series offers complete cardioid, hypercardioid packages in either black or white non-reflective finishes. The standard 30ft. cable connects through a mini-XLR to the standard in-line phantom powering module. (An optional module allows battery powering and includes a rolloff filter.) The complete cardioid microphone package with windscreen and wire hanger carries an MSRP of $249 in black, with white slightly higher. An omni capsule is available on special order.
Sennheiser adopts the “fully modular” approach to its hanging microphones, applying it to the ordering process as well. The basic system starts with the capsule suspension device, the MZH30 ($22), and the MZC30 in-line power module with 0.04in. Kevlar-reinforced cable (29.5ft.) with integrated preamp ($219). From there, the user can select an ME 34 cardioid, ME 35 super-cardioid, or ME 36 line cardioid capsule to realize the desired pickup characteristics. Performance is excellent, with low noise and flat, uniform response curves. However, the only available color is matte black.
Shure takes a different twist — literally — on the hanging concept by using an integral 4in. gooseneck (rather than an external clip) for positioning capsules in its MX202 Microflex line. Available with a choice of cardioid, supercardioid, or omni capsules, the MX202 connects to either an in-line or box plate power module through a 30ft. cable. MSRP for the complete system is $284 for the cardioid and $294 for the supercardioid. Shure does not stock an MX202 omni system, though an omni capsule is available on special order.
The microphones in the following section are all-in-the-box, one-order solutions. With noted exceptions, all employ a cardioid capsule and offer only an in-line power module. AKG's offering in the single-unit category is the CHM 21, a “Euro-styled” model equipped with a spring-steel hanging clip and a 33ft. cord that connects to the powering module. The finish is a discreet charcoal gray, and a battery power supply is available optionally.
Avlex offers both cardioid (HM-81) and hypercardioid (HM-85) hanging microphones, though the hypercardioid (Avlex's term) appears more like what is termed here as a line cardioid. White or black models are available, as well as either in-line or wall plate powering modules. The cardioid version is available with 30ft. or 60ft. cables; the hypercardioid offers a 30ft. cable only.
CAD Professional Microphones and Astatic are two sister companies under the umbrella of Ohio-based Omnitronix, and the company's two divisions offer two hanging microphones with striking similarities. Available in black or white, both the Astatic 900 and the CAD CM100 have a cardioid capsule mounted on a thin gooseneck. The 30ft. cable terminates in a mini-XLR for connection to the power module. Immediately behind the capsule is a 0.22in. hole to accommodate monofilament line for precise capsule positioning. Specifications for the two models are close, but not identical, which could be due to measurement discrepancies or slight variations in capsule design.
Crown's entry is the supercardioid-only CM-30, which is available in black or white. The CM-30 designation applies to the wall/ceiling-plate version, while the otherwise identical CM-31 offers an in-line phantom powering module.
Electro-Voice has two offerings that, despite occupying the same general turf, display significant differences. The RE90H is slightly larger and has a distinctive jet engine pod shape to it. Self-noise is good, and it has one of the highest sensitivity ratings of the lot, though the maximum SPL rating of 120dB is at the lower edge of the group. The trimmer and squared-off RE92, in contrast, handles up to 135dB but with lower sensitivity; it also claims a more extended high-end response. Both are available with black or white finishes and a 25ft. cable connecting to the in-line electronics module.
Originally known as a wireless mic specialist, Nady Systems has branched out to become a supplier across virtually every category of audio equipment. The company leverages tendencies toward “value engineering” with attractive pricing, and the sub-$100 OHCM-200 is no exception. All the essentials are there, and published specifications are creditable. However, noise and maximum SPL figures are not given, the attached cable is only 20ft. long, and only black finish is available.
The Samson CM12C is an installation product from another broad-range supplier. The published specifications for this microphone do include good noise and maximum SPL (136dB) ratings, and the cord is 30ft. long. A multi-stage windscreen is included, but again, only a black finish is offered.
Shure's EZO Easyflex eschews the gooseneck approach of the MX202 in favor of the more familiar flexible wire hanging apparatus. Both noise and sensitivity figures are good for the price point, and the polar pattern exhibits excellent uniformity. Frequency response exhibits a rising characteristic to bring out the upper registers between 5kHz and 10kHz.
Wrapping up the group, and displaying all the familiar characteristics, is the MCHM-300 from Speco Technologies. Frequency response and sensitivity are good, but noise specifications and polar patterns are not published on the data sheet. Only a black version is shown.
Several microphones fell just outside the technical boundaries of the survey, but are nevertheless commonly used in hanging applications — worship choirs in particular.
First are several “micro” microphones that are integral units, with the powering/preamp electronics in the same body as the capsule. Audio-Technica's popular PRO 45 cardioid (black or white) is a prime example, with a total length of 2.24in. and the 0.5in. diameter essentially the same as the “regular” group. A permanently attached 25ft. cable terminates in a full-sized XLR-M connector. The sensitivity (14.1 mV, re 1V/1 Pa) and signal-to-noise (66dB) are quite good considering the attractive MSRP of $135.
Also in this category are the Micros from Audix. The M1244 cardioid ($379) and hypercardioid ($399) are a mere 1.7in. long and less than 0.5in. in diameter, connecting to the outside world through supplied cables with a mini-XLR at one end and a full-sized version at the other. The novel cable hanger is clear plastic with an adjustment screw for desired tilt angle.
Beyerdyamic's MCE 530 ($219) crosses over the borderline here — it does incorporate a standard XLR connector, thus necessitating a diameter of over 3/4in. However, it earns mention because the 3.9in. carbon-fiber reinforced-resin casing limits weight to 1.3oz. The flat frequency response and uniform polar pattern could make the slightly more obtrusive appearance worthwhile.
When the microphones need to largely disappear, the hanging versions of Countryman Associates' micro-miniature Isomax 2 are worthy of consideration. Available in black or white and cardioid or omni, the Isomax offers a wide frequency response and good maximum SPL handling, though sensitivity is on the low side. The capsule connects to the powering module through a 50ft. cable designed to maintain orientation with temperature changes. An integral wire stiffener allows capsule positioning.
PUSHING THE ENVELOPE
Finally, to take the category into the upper limits of performance (and budget), we have the KM 100 series of microphones from Neumann. The company does not actively market these as hanging microphones for the applications discussed here, but that doesn't mean they won't work — and work exceedingly well. One Texas-based consultant who works with musically demanding churches likes to specify the KM 145 ($1,200) and KM 150 ($1,400) capsules. Rather than limiting placement to single microphones according to the standard “3 to 1” rule, he often mikes choirs using broadcast-oriented stereo coincident methods.
True, the precise mounting methods needed to place a pair of Neumann capsules at just the right orientation may be somewhat less than discreet. But certainly these would be hanging microphones that everybody could look up to — and respect.
For More Information
Bruce Borgerson is a technical writer, consultant, and neophyte digital content producer based in Ashland, Ore.
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