M&K V-125 Subwoofer Review

Although Miller & Kreisel (M&K) manufactures a full line of loudspeaker systems, the company is perhaps best known for its powered subwoofers. One of the newest among them is the V-125.

The V-125 is relatively large and heavy compared with some of the other subwoofers we have tested recently. Its nominally 12-inch driver (the actual effective cone diameter is about 101/2 inches) faces forward behind a removable black cloth grille that covers the entire front of the all-black cabinet. Unlike many other subwoofers, the V-125 is magnetically shielded, enabling it to be used close to a video monitor or TV set. The fully sealed enclosure also contains an amplifier rated at 125 watts output.

In addition to a large heat sink for the internal amplifier, the V-125’s back panel is well populated with connection terminals and controls. This is an unusually versatile powered subwoofer, with RCA-jack inputs for line-level signals from a preamplifier or an A/V receiver’s subwoofer output, as well as spring-clip wire connectors for the right- and left-channel speaker output signals of a power amplifier or receiver and similar connectors for outputs to a pair of satellite (main) speakers.

Among the controls on the back panel is a toggle switch that reverses the phase of the subwoofer output relative to the main program signal. The manual discusses the procedures for setting this switch, which must be done after the system is set up and operating. There is also a knob that smoothly varies the subwoofer’s low-pass filter cutoff frequency between 50 and 125 Hz (with approximate calibrations at 50, 60, 75, 100, and 125 Hz). Another knob adjusts the subwoofer’s level to blend properly with the output of the main speakers.

A handy feature, whose use is optional, is a built-in high-pass filter, accessible only through the speaker-level inputs, which excludes program content below about 80 Hz from the main speakers. M&K suggests experimenting with this operating mode, since its effect on the sound quality is related to the bass capabilities and impedance characteristics of the main speakers.

The V-125 has no power switch (although a small red LED on the rear indicates that it is turned on), and M&K recommends that it be left powered continuously. The heat sink becomes only slightly warm in extended operation, and the only clue to the amplifier’s continuous power drain is its 2-ampere slow-blow power-line fuse. Presumably the standby power consumption is small enough to have a negligible effect on your electric bill. The V-125 comes, by the way, with one of the most complete subwoofer installation and operation manuals we have seen.

We plotted the V-125’s frequency response with close microphone spacing, resulting in an essentially anechoic measurement. A family of curves was generated, one for each of the calibrated low-pass cutoff frequencies, on a single graph. The maximum output occurred at about 60 Hz, sloping down at about 6 dB per octave from there to our lower measurement limit of 20 Hz. At the highest setting of the frequency control (125 Hz), the output was flat within 6 dB from 28 to 125 Hz. The crossover slope, at frequencies above about 100 Hz, was approximately 36 dB per octave. That’s an exceptionally steep cutoff, which should aid appreciably in making the subwoofer nonlocalizable by ear.

We measured the distortion of the V-125 with its level set to give a 100-Hz sound-pressure level (SPL) of 90 dB at a distance of 1 meter. The distortion was a minimum of 0.35 percent at 70 Hz and remained less than 1 percent from 50 Hz to well beyond the top crossover frequency of 125 Hz. At lower frequencies the distortion (principally odd harmonic) rose to about 10 percent at 25 Hz. Atypically, there was no obvious waveform clipping from amplifier overload, presumably forestalled by M&K’s Active Headrqom Maximizer circuit.

As the crossover control was turned down, the output remained constant below 40 Hz, while the higher frequencies were smoothly attenuated above the selected cutoff frequency. The difference between the two lowest curves (cutoff at 50 and 60 Hz, respectively) was negligible.

We operated the M&K V-125 with a pair of small speakers whose low-frequency response was adequate down to about 80 Hz, so we used that approximate setting of the crossover control. The V-125’s control flexibility simplifies its adjustment, although we did not experiment extensively with positioning and polarity switching.

That flexibility makes the M&K V-125 well suited to use in a wide variety of installations. Although its low-frequency “reach” was not quite as deep as that of some subwoofers we have used, its output was audibly strong and clean down to 30 Hz and still useful into the 20’s. And few other subwoofers can match its ease of installation, setup, and operation. It is a very appealing choice for anyone seeking the powerful rumble of a high-performance subwoofer at a reasonable price.

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