The YBA's midrange was more laid-back than the Audio Research Classic 120's, though the Mark Levinson No.20.6 monoblock softened the mid-treble further. The YBA wasn't reticent in the high treble, though, once…
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Overall dynamics were punchy. Mahlerian climaxes were not reined in; Eddie Van Halen's essential guitar lines on Latoya's slightly-more-famous brother's "Beat It" raggedly ripped around the room. Even at high levels, the amplifier's sound didn't harden or become fatiguing. This amplifier has more power (la puissance, en français) than you'd expect from its modest physical size.
Sidebar 1: Specifications
Description: Dual-mono solid-state power amplifier. Maximum power output: 70W into 8 ohms (18.5dBW), 140W into 4 ohms (18.5dBW). Frequency response: 5Hz-80kHz, -3dB. Input sensitivity: 120mV RMS for 1W/8 ohms, 1.1V RMS for rated output. Input impedance: 27k ohms. Output impedance: 0.02 ohms (damping factor quoted as 400 at 100Hz). Risetime: 3µs at 10kHz. S/N Ratio: 100dB (reference and conditions not stated). Power consumption: 100VA idling, 1000VA at full power.
Dimensions: 16.9" (430mm) W by 13" (330mm) D by 3.75" (95mm) H. Weight: 26.4 lbs (12kg).
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Sidebar 2: System
Due to both mid-life confusion and a change in distributor during this review's preparation, I used the YBA 2 HC and its matching preamplifier, the YBA 2, for an uncommonly long period of time—over two years (footnote 1). Thus it was also used with all the loudspeakers I've reviewed in that period. However, I fondly remember the Epos ES11s, Magnepan MG2.6/Rs, Spendor S100s, Acoustic Energy AE1s, Thiel CS2 2s, Vandersteen 3s, PSB Stratus Minis, Mission Cyrus 753s, Martin-Logan Aeriuses, and Harbeth HL-P3s. The comments are an amalgam of the listening notes I took with…
Sidebar 3: Measurements
All measurements were made after the YBA 2 had been preconditioned by running it at one-third full power into 8 ohms for an hour, which thermally stresses the amplifier to the maximum. Its heatsinks were very hot at the end of this period. Interestingly, however, those who say that solid-state components need no warmup should note that the amplifier's THD+noise, initially 0.09% for 1W into 8 ohms, dropped by a factor of more than five—to 0.016%—by the end of this preconditioning period.
The YBA 2 HC's voltage gain measured 27.6dB into an 8 ohm load; its…
Given the YBA's rising distortion at high frequencies, I was concerned that it would generate intermodulation products when asked to put out high levels of high frequencies. This didn't turn out to be an issue into higher-impedance loads, as revealed by fig.8, which shows the audio-band spectrum of the amplifier's output when reproducing a 1:1 mix of 19 and 20kHz sinewaves at 40W into 8 ohms. Though the 18 and 21kHz sidebands lie at -57dB and -53dB, respectively, the audible 1kHz IM product (the difference tone) is 66dB down from the level of either fundamental. At high powers into 4 ohms (…
Jonathan Scull wrote a Followup on the YBA 2 HC in October 2000 (Vol.23 No.10):
I was on the phone with John Atkinson. He'd almost scratched a hole in his head trying to figure out how to do the Follow-Up of the YBA 2 before moving from Santa Fe to New York. I heard a flashbulb pop.
"Unless..." he said sweetly, "....you wanna do them, J-10!"
It's hard to describe the sound of the other shoe dropping, but I heard it.
"Uh...okay, JA!"
I had reviewed the YBA Signature 6 Chassis preamplifier and Passion 1000 monoblocks, so I was familiar with YBA's "house…
MACH 1 Acoustics? Cute name. Mach 1 is, of course, the speed of sound—the speed at which a loudspeaker's acoustic output is forever constrained to travel. Quite a fitting choice for Marc McCalmont, Marine and jet pilot turned speaker designer. Marc retired to Wilton, NH together with Melissa. (Oops, that should be MLSSA, the well-known acoustic analysis system—not Marc's girlfriend.)
MACH 1 started off by selling their DM-10 loudspeaker direct to the public with a 30-day return policy, but has now set up a small network of specialist retailers. The company has kept up its profile in the…
Sidebar 1: Specifications
Description: Three-way dynamic loudspeaker with sealed-box bass alignment. Drive-units: 1" concave ceramic-dome tweeter, 5.5" polypropylene-cone midrange driver, 10" woofer. Crossover frequencies & slopes: 250Hz, 3kHz, fourth-order Linkwitz-Riley filters. Frequency response: 30Hz-20kHz, ±3dB. Nominal impedance: 6 ohms. Sensitivity: 89dB/W/m. Recommended input power: 35-500W.
Dimensions: 13" W by 46" H by 16.5" D. Weight: 150 lbs each.
Serial numbers of samples tested: 107A/B.
Price: $10,995/pair (1994). Optional spiked, nonresonant platforms: $250/…
Sidebar 2: Measurements
The DM-10 Signature generally doesn't make too many demands on the amplifier. Its calculated B-weighted sensitivity was a little below specification but still average at 87dB/2.83V/m, while its impedance plot (fig.1), measured with the Audio Precision System One, didn't drop below 4 ohms, and with only minor-magnitude changes above the upper bass. This means that its sound won't change significantly with amplifiers featuring high output impedances. Phase-angle values, too, are generally small. Note, however, that in the midbass, a lowish magnitude is combined with…
Martin Colloms offered some thoughts in April 1994 (Vol.17 No.4):
In his review of the Mach 1 Acoustics DM-10 Signature loudspeaker (p.131), Dick Olsher correctly perceived somewhat limited low bass from the DM-10, despite a respectably low measured system resonance at 24Hz. With a modest bass Q factor, fair in-room bass should have been available down to 25Hz if the woofer excursion was up to it.
The reason for the discrepancy can in fact be seen in the individual response of the woofer and in the electrical signal actually driving the woofer motor coil, available thanks to the…