Mach 1 Subwoofer.
Source: Manufacturer loan
Reviewer: James T. Frane
There was a time, not too long ago in my memory, when very few subwoofers were on the market. Of those, only a few had the advantage of being self-powered, with a built-in amplifier and electronic crossover. A built-in amp allows the designer to match amp to speaker and relieves the regular system amplifier from supplying the extra power needs of the subwoofer. Also, a powered subwoofer may let the user drive the main speakers with a lower powered (and usually less expensive) amplifier. The electronic crossover lets the user make adjustments to more closely match the sub with the main speakers. I recently had the opportunity to audition a powered sub from Mach 1 Acoustics, the manufacturer of my main speakers.
The Mach 1 Subwoofer, complete with built-in amp and electronic crossover, is 24.5" high x 18.5" wide x 17.125" deep. The enclosure is made of 1" thick MDF (medium density fiberboard), a material common in the loudspeaker industry, but thicker than the usual 0.75". The top, front, back, and bottom are finished with a knubby texture semi-gloss black with minute white flecks. The extra thickness of MDF, coupled with internal bracing and 0.75"-thick cherry veneer plywood panels over the sides, make for a rigid enclosure. It weighs in at 98 pounds by my scales. The rigidity demonstrates its value in clean bass. A 0.25" plate glass panel graces the top, both for decoration and protection.
The 150-watt solid-state amplifier/crossover unit is recessed into the back of the enclosure. Although the amp has a power switch, it is designed to be left in the on position, unless the system is not used for an extended period. An incoming signal turns on the amp, which turns off again after some period of signal absence. The amp's heat is dissipated by exposed heat sink fins. The heat sink fins and control knobs protrude about 1.125". Even on very warm days, the amp heat sink fins never became warmer than the ambient temperature. The subwoofer amp combines the left and right channel signals. A small red light indicates the amp is powered up with an incoming signal. The electronic crossover can vary the frequency from 40 Hz to 200 Hz. A phase switch permits selecting 0 degrees (in phase) or 180 degrees with relation to the main speakers. There is a crossover bypass switch for using the sub with a surround sound processor that has its own crossover. A volume control can be used for to match levels.
There are two ways to connect the subwoofer to the rest of the system: 1) from the preamp using interconnect cables and 2) from the system power amp using speaker cables. In the first configuration, the satellite speakers can be connected to the subwoofer output and are controlled by the electronic crossover. Alternatively, the satellites can be connected directly to the system amplifier and be run full-range.
In the second method, the satellite speakers are connected to the system amp, which is controlled by either direct connection to the preamp or to the subwoofer electronic crossover output jacks via another set of interconnect cables. In the latter configuration the system amp and the satellite speakers are regulated by the subwoofer crossover. In the former, the satellites are run full range. Mach 1 prefers long interconnect cables to long speaker cables because speaker cables are more susceptible to interference from AM pickup.
The enclosure interior is divided into a front ported section and a rear sealed section. The 10" woofer is mounted in the sealed section and fires into the ported section. The whole forms a bandpass enclosure with -3dB points at 20 Hz and 80 Hz. All of the sound emerges through a 0.75"-high port that is nearly as wide as the back baffle. The port extends 15" from the front section to near the top of the back baffle where all of the sound emerges. The subwoofer enclosure is supported on several of Mach 1's vibration absorbing feet mounted on the bottom of the enclosure at each corner.
Associated Equipment: For this review, my stereo system consisted of a Parasound HCA-1000A power amplifier controlled by a Carver CT-17 preamp-tuner used alternately with a SimAudio P3 preamplifier. Speakers are Mach 1 model M-Twos supported on a pair of NHT SW3 subwoofers run in dual mono and separately driven by an NHT SA-3 power amplifier with integral electronic crossover. The M-Twos were run full-range, and the NHT low-pass control was set to about 40 Hz. Interconnect cables were by Mach 1, Gotham, WireWorld, and Monster Cable, and speaker cables were Kimber 4PR alternated with Mach 1 cables to the Mach 1s and Original Monster Cable to the NHTs. Sources were a Sony CDP-XA20ES CD player, a Thorens TD320 Mark III turntable with Grado Prestige Red cartridge, and a Denon TU-767 AM-FM tuner.
Use and Listening: I set up the Mach 1 sub in my two-channel stereo music system close to the right M-Two satellite speaker to minimize the cable run from the preamp and power amp. The sub was about 3.5 feet in front of the front wall and was even with the fronts of the M-Two speakers. I used the sub with the signal coming from the preamp and at other times from the Parasound power amp. I noted no sonic differences between the two methods.
I used pink noise and my ADC SS-525X 2/ 3-octave spectrum analyzer with calibrated microphone to balance the sub output level with the M-Two main speakers. With a healthy 70 dB subwoofer output at 25 Hz, combined speaker response at 40 Hz was 72 dB and 70 dB through 250 Hz. Phase was set at zero (the sub and satellites in phase), and the sub crossover was set at about 70 Hz. These results demonstrate the flexibility of the sub's built-in electronic crossover to allow such close matching. The sound was smooth and seamless from 25 Hz up. The sub went lower than the 25 Hz limit of my measurement capability. There was no localization of the sub--in fact, if one didn't see it, the deep bass might have been coming from the relatively small M-Twos. The flat frequency response in the area where the sub and satellites blend improved the sense of realism. The sub made its presence known only when there was music content in the lower register. The electronic crossover kept the sub out of the range of voices. Overly resonant male voice is often a fault with an uneven match between sub and satellite and also with speakers having a bump in the response between 60 and 150 Hz. I used a wide variety of music, including male and female vocals, jazz, classical, and vintage rock, all with good results.
The next part of the listening process was to incorporate the Mach 1 sub into my modest home theater system. This system, set up in another room, comprises a Sherwood RV-1340R surround sound decoder-receiver driving a Cambridge SoundWorks Ensemble satellite-subwoofer system for the front speakers and two pair of Cambridge SoundWorks Ambiance rear speakers. The latter are wired in bipolar configuration with the null area toward the back of the listening area to ensure they cannot be readily localized. Cables are home-made twisted pair solid core to the front main speakers, Kimber to the subwoofers, and 12-gauge stranded to the rear speakers. I replaced the Ensemble subs with the Mach 1 sub, and WHAT A DIFFERENCE! The Ensemble subs work well, but because of their relatively small size (4.25" x 11.75" x 21"), are really more woofer than subwoofer. With programs having deep bass, the Mach I provided deeper and more prominent bass than the Ensemble. It was bass that blended well with the satellite speakers. The variability of the built-in electronic crossover once again permitted a good match. This is despite the very different size (smaller),and sensitivity (lower) of the Ensemble satellite speakers compared to the M-Twos. This sub went significantly deeper than the small Ensemble subwoofers, adding a solid foundation to the sound where the deep bass was present in the source. As with the two-channel system, bass showed up only in the lowest part of the frequency spectrum. The Mach 1 never affected the timbre of voices unless the crossover frequency was set too high. I neither measured nor detected any sonic anomalies with the Mach 1 subwoofer. When I held my hand at various spots on the enclosure while the sub was running, there was very little vibration, the sign of a sturdy and well-braced enclosure.
Conclusion: I have tried other subwoofers in my system. The Mach 1 blends better than some of the others have, and is as good as my NHT system, which is to say it works as I want it to. When bass was present it was clean and clear with no audible distortion. The flexibility of a variable electronic crossover can make a seamless blend with satellite speakers. A source of pink noise at each octave and a sound-level meter can make the speaker matching faster and possibly more accurate. The Mach 1 subwoofer amp has been chosen to interface well with the Mach 1 driver, as has the crossover, which may result in a better combination than is likely with separately purchased components. The connection options provide versatility. The Mach 1 subwoofer is well thought out and solidly constructed.
While not inexpensive, the Mach I is competitively priced with many powered subwoofers. If you are considering a powered subwoofer, the Mach 1 subwoofer has the power, flexibility, and deep bass output to be a Sensible choice. - JTF