CADM179

by Andrew Thompson

History

One of the most significant indicators in the professional audio market of the early-to-mid 2000s was the rapid and dramatic fruition of what came to be known as the home and project studio revolution. This period saw new and previously marginal manufacturers find substantial success with disruptive new products, giving many more established names cause for urgent introspection and, ultimately, to thoroughly overhaul their own offerings.

Among those model stories of the former class is that of the Ohio-based brand CAD, which in the first half of the decade moved its manufacturing operation from the US to China. The company had been founded in 1988 as the pro audio division of Astatic Commercial Audio Products, a venerable 20^th-century firm that by that time was a manufacturer of address microphones for industry. CAD’s Equitek series of microphones had been popular foretokens of the low-cost insurgency to come, and their redesigned successors, the M177 and M179, would hew still closer to this model.

Response

Like the Equitek microphones, the M177 and M179 were large-diaphragm condensers. The M177 featured a single cardioid pattern and is no longer produced, but the M179 is multipattern, with omnidirectional, wide or sub-cardioid, cardioid, hypercardioid and bidirectional polar patterns obtainable via a continuously variable rotary control with a centre detent for the cardioid pattern; an unusual feature at the M179’s price point. The microphone is a functionally typical LDC, being a side-addressed “bottle” shape with controls on the address side of the body. The microphone is quite small, 178mm by 51mm, and its distinctively designed housing is constructed around a sturdy frame which supports the head amplifier circuit boards and the microphone capsule and is covered by front and rear metal side panels finished in grey urethane. Access to the interior of the housing is obtained via four screws on the rear panel.

The head amplifier circuit is a novel design using op-amps, which, users will be relieved to hear, are “laser-trimmed”. The capsule is apparently a custom K67-type centre-terminated design, made in China. Signal and +48V phantom power are carried via the standard 3-pin XLR connector. It should be noted that the microphone draws 0.8mA; a great deal of current for a condenser mic and users should check that their phantom power supply is adequately specified. A -20dB pad is included, along with a -6dB/oct high-pass filter at 100Hz, both of which are engaged via sliding switches on the front panel.

Sensitivity is rated at 16 mV/Pa, a slightly unusual medium position. Self-noise is a very respectable 11dB. With the pad engaged, the mic is rated to handle a maximum of 143 dB SPL.

Frequency plots for the M179’s three principal patterns claim an essentially flat response to frequencies all the way down to 10Hz, which is in itself remarkably low, and up to 3kHz – an impressive degree of linearity for any microphone, let alone one aimed at the budget-conscious recordist. An individual anechoic plot of one 2001 unit’s cardioid pattern bears this out in broad strokes, but shows a very gentle “V” pattern centred on 900Hz, where attenuation is in the order of -2.5 or -3dB, neutralising at 100Hz and 4kHz. Though the individual plot only shows frequencies above 20Hz, it does indeed indicate a more or less linear response to low frequencies in the cardioid pattern trending upward from zero at 100Hz to possibly +.75dB at 20Hz. The manufacturer’s generic graphs for the cardioid or omnidirectional patterns make no mention of this slight positivity, though a slight bass “hump” is expected in the bidirectional pattern, between 40Hz and 90Hz, peaking around +2dB at 55Hz.

All three patterns report some variation of two slight peaks in the presence region and a larger third in the high frequencies above 10kHz. In the cardioid pattern, the former deviates +2dB from zero at 3.5kHz and +3dB at 6.5kHz, the latter rising to about +5dB at 14kHz.

The two presence bumps are very slightly more dramatic in the bidirectional pattern, though still very modest at +3dB and +5dB, and occur slightly higher in the frequency spectrum at just below 4.5kHz and 7kHz. Response dips just into attenuation around 10kHz – at most -2dB – and the high-frequency boost around 15kHz is longer, flatter and more modest at only +3.5dB.

The omnidirectional pattern again features small presence peaks at 4.5kHz and 7kHz, but sensitivity does not decline to zero between them, and indeed response stays positive all the way up to 17-18kHz. The high-frequency peak is both lower in the spectrum and much more pronounced than in the other patterns, reaching +8dB at about 13.5kHz.

In all three patterns response falls off steeply after 15kHz, crossing zero into attenuation around 17kHz.

The cardioid pattern shows attenuation in the order of about -6dB at 90 degrees off-axis, -10dB at 120 degrees and in excess of -25dB at the rear, and claims consistency up to 1kHz. Above 5kHz the pattern becomes increasingly hypercardioid, losing integrity in the front lobe at 10kHz.

The figure-8 pattern is most sharply defined around 500Hz where attenuation is about -23.5dB at 90 degrees and -5dB at 60 and 120 degrees off-axis. Rear and front lobes are very slightly (around -2dB @60 and 120 degrees) impaired at 100Hz and 1kHz, with the null points at 90 degrees being some 5dB and 2.5dB less pronounced respectively. Off-axis sensitivity is enhanced in the presence region, similar to the pattern’s on-axis response, and though the null points are still well-defined at 90 degrees, access to them is correspondingly somewhat more restricted between 5kHz and 10kHz. At 15kHz the pattern is considerably narrowed, with attenuation reaching -5dB at around 35 degrees off-axis.

The omnidirectional pattern is consistent below 10kHz, above which it loses integrity at 90 degrees and trends toward a figure-8.

Uses

The M179 is a cost-effective performer in terms of on-axis fidelity, can handle very high sound pressure levels with the pad engaged, is robustly built and is physically quite small for its class; all of which should make it an attractive option on drums – indeed it is often cited as a favourite on toms, and sometimes bass drum. Some users may find the shape of the M179’s high-frequency enhancement less suitable than other microphones for vocals in the cardioid pattern, but sound should at least be natural and free of excess sibilance.

One clear advantage the M179 can lay claim to is its apparently extremely linear and extended bass response. Instruments that make fundamental use of the 20Hz-100Hz range inarguably stand to benefit, assuming the occasion suits a condenser design. Off-axis response is generally very consistent under 10kHz, so larger instruments and ensembles should be approachable with the M179 provided fidelity to HF harmonic content is not considered critical.

Andrew Thompson

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