I regret that, to some, I came off as arrogant or condescending. It’s not that I have a golden ear; rather, I’ve had sufficient experience with the particular performers and compositions in the recordings used at…
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When I reread my February “As We See It,” Music? Or Sound?, my first thoughts about a piece I had written a while ago were: (1) I wish I’d devoted less space to telling the story and more to expanding upon my thesis; and (2) I’m afraid that my motivation will be misconstrued. Indeed, the flurry of furious comments makes clear that I failed to make the best case for my argument.
I walked into BSG's room at the Newport Beach Show in June 2012 unsure of what I was going to hear. I was well aware of this new company's qøl Signal Completion Stage ($3995), but didn't know if it was a genuine step forward in audio reproduction, or just another example of the hokum found on the fringes of our hobby. I took my listening seat, and BSG's CEO Larry Kay, cofounder and erstwhile publisher of Fi magazine, performed A/B comparisons with the qøl's processing in and out of circuit.
Fascinating.
As I wrote in my show report, the difference between bypass and process was…
The BSG patents suggest that no equalization is used, but if qøl is a variant on the shuffler, multiplying the Difference signal by the Golden Ratio will widen the stage of the resultant stereo signal at all frequencies, as well as give a small increase in volume. And because the Difference signal carries information that is uncorrelated between the original channels, BSG's qøl process will increase the audibility of things like ambience and reverberation.
The Signal Completion Stage
The Signal Completion Stage is impressively well made, considering it's the first product from a…
Sidebar 1: Specifications
Description: Remote-controlled, solid-state signal processor with four analog inputs (duplicated on balanced XLR jacks and unbalanced RCA jacks). Analog outputs: 2 pairs balanced on XLRs, 2 pairs unbalanced on RCAs. Frequency response: 10Hz–50kHz, ±0.25dB. THD+noise: 0.001% (6V balanced input at 1kHz, 20Hz–20kHz). Maximum input levels: 10V balanced, 5V single-ended. Maximum output levels: 10V balanced, 5V single-ended. Input impedances: 20k ohms balanced, 10k ohms single-ended. Output impedances: 50 ohms balanced, 10 ohms single-ended. Signal/noise: >106dB,…
Sidebar 2: Associated Equipment
Analog Sources: Linn Sondek LP12 turntable with Lingo power supply, Linn Ekos tonearm, Linn Arkiv B phono cartridge.
Digital Sources: Ayre Acoustics C-5xeMP universal player; Apple 2.7GHz i7 Mac mini laptop running OS10.7.5, iTunes 10, Pure Music 1.86; Ayre Acoustics QA-9 USB A/D converter; Metric Halo MIO2882+2D digital processor.
Preamplification: Liberty B2B-1 phono preamplifier, Classé CP-800.
Power Amplifiers: Classé CT-M600, Lamm M1.2 Reference (both monoblocks).
Loudspeakers: KEF LS50, Vandersteen Treo.
Cables: Digital: DH Labs…
Sidebar 3: Measurements
I measured the BSG qøl Signal Completion Stage with Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It"). The BSG was non-inverting from all inputs to all outputs, in both active and bypass modes, with the XLR jacks wired with pin 2 positive. The input impedance was usefully higher than specified, at 18k ohms single-ended and 41k ohms balanced. The balanced output impedance was to specification, at 53 ohms at all audio frequencies, while the unbalanced output impedance was much lower,…
What better way to celebrate the expiration of a noncompetition clause than to debut a product that has no competition? That's what Dan D'Agostino appears to have done with his Momentum monoblock amplifier ($55,000/pair)—his first new product since leaving Krell, the company he cofounded more than 30 years ago.
First shown a year and a half after the split, the Momentum has created something of a sensation in the audio world, due in equal parts to D'Agostino's long history of innovation in the design of high-performance audio circuitry and the amplifier's stunning looks. Visually, the…
I've heard very fine amplifiers that produced more bass weight, and brighter and sharper high-frequency transients, than the D'Agostinos. I've heard amplifiers that were more billowy in the lower mids, and drier and more reserved in the upper mids. I've heard some that were more polite, some that were more brash. I've heard amplifiers with faster attack and more generous sustain. All of these are noticeable qualities that, once you hear them, you always hear, like it or not—or you work around them with associated gear.
After spending a great deal of time listening to the Momentums, I…
Sidebar 1: Specifications
Description: Solid-state monoblock power amplifier. Inputs: 1 balanced (XLR). Output power: 300W into 8 ohms, 600W into 4 ohms, 1200W into 2 ohms (all equivalent to 24.8dBW). Voltage gain, input impedance, output impedance: all not specified. Frequency response: 1Hz–200kHz, –1dB; 20Hz–20kHz, ±0.1dB. THD (300W at 8 ohms): 0.1% at 1kHz. Signal/noise: 105dB, unweighted (no reference given).
Dimensions: 12.5" (317.5mm) W by 5" (127mm) H by 21" (533.4mm) D. Weight: 95 lbs (43kg).
Serial numbers of units reviewed: 0265, 0266.
Price: $55,000/pair.…
Sidebar 3: Measurements
To measure the Dan D'Agostino Momentum amplifier, I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It"). Before I test an amplifier, my usual procedure is to run it at one-third power into 8 ohms for an hour. With a conventional amplifier using a class-A/B output stage, this level results in the maximum heat dissipation in the output devices. Unfortunately, after running at this level for 50 minutes, serial no.0265 turned itself off, with its heatsinks way too hot to keep my hand…