To get a handle on the YBA 1 Alpha HC's performance in comparative terms, I spent a lot of time switching back and forth between it and the Jeff Rowland Design Group Model 2. In many ways, these amps are natural peers/competitors. They have similar power ratings (Rowland, 75Wpc; YBA, 85Wpc); they're in roughly the same price range (Rowland, $5800; YBA, $7000); they're both small but heavy; and both represent their designers' at-times-fanatical pursuit of the twin goals of accuracy and musicality. The Rowland Model 2 is firmly…
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RD returned to the Model 2 in June 1996 (Vol.19 No.6):
RD added the BPS-2 battery power supply in July 1997 (Vol.20 No.7)
Like many audiophiles, I've been impressed with the effectiveness of dedicated AC lines and line conditioners. Although power supplies in audio equipment are supposed to provide isolation from the various sorts of interference (EMI and RFI) that may be present on AC, cleaner AC power usually translates to cleaner sound. If reducing EMI/RFI from the power source is worthwhile, it follows that eliminating it should be even better (footnote 1). This is the promise of battery power: by having a source of pure DC, you are, in…
Sidebar 3: 1997 Review System
Analog Source: Fully updated Linn LP12 turntable, Ittok tonearm, AudioQuest AQ-7000nsx cartridge.
Digital Sources: PS Audio Lambda II and Sonic Frontiers SFT-1 transports, Audio Alchemy DTI•Pro32, Sonic Frontiers SFD-2 Mk.II digital processor, Illuminati D-60/Orchid digital links; Sonic Frontiers SFCD-1 CD player.
Preamplifiers: Convergent Audio Technology SL-1 Mk.II, Balanced Audio Technology VK-5i, Jeff Rowland Design Group Synergy.
Loudspeakers: Dunlavy Audio Laboratories SC-IV, Vienna Acoustics Mozart.
Interconnects, speaker cables, power…
Sidebar 4: 1997 Measurements
All measurements on the Rowland Model 2 were made with the amplifier in its high-impedance input setting at a gain of 26dB, unless otherwise noted. All of the measurements were, of course, balanced. And all of the measurements, again except as noted, were made with the battery functioning normally (battery connected to the line for constant recharge, amp operating off the battery).
Following its 1/3-power, one-hour preconditioning test, the Model 2's heatsinks were very warm but not hot. The Rowland Model 2's input impedance measured 44k ohms (720…
Sidebar 5: Specifications
Description: Solid-state stereo power amplifier. Power output: 75W into 8 ohms (18.75dBW), 150W into 4 ohms (18.75dBW). Power bandwidth: 0.5Hz-160kHz -3dB. THD+noise: <0.05% at rated power. Damping factor: >100, 20Hz-20kHz, 8 ohms, equivalent to an output impedance of less than 0.08 ohms. Output current: 20A continuous, 35A peak. Overall gain and sensitivity: 26dB or 32dB; 141mV or 72mV (1W, 8 ohms). Input impedance: 36k ohms or 600 ohms. Common-mode rejection ratio: >60dB, 20Hz-20kHz. Power consumption: 25W standby; 225W idle; 400W maximum.
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Everyone's going crazy for single-ended power amplifiers. What's the big deal? What is it about these relatively low-powered contraptions that could make everybody so nutso? And has Pass Labs' Nelson Pass completely lost his marbles, selling a 30Wpc amplifier for a price that can buy a high-quality 200Wpc amp? Isn't that 200W amp seven times as loud—and seven times as good—as a 30W amp?
First of all, while a 200W amplifier is 8dB more powerful than one rated at 30W, that 8dB sounds only about twice as loud to the human ear, not the seven times you'd expect. For an amplifier to play music…
The Aleph 3's is of modest weight compared to other high-end amps. Also, its relatively compact dimensions facilitate placement within the room. It's necessary to give it plenty of space for ventilation, though. Pass recommends 6" of space on all sides and top. The amp's constant 250W heat output feels like a lot in the summer, but it isn't enough to require extra air conditioning. (For comparison, that's only about a third of the heat output of an old Krell KSA-250.)
All external connectors are located on a cramped panel at the rear, between two heatsink fins. This maximizes the…
Snooping around the lovely interior, I unfortunately noticed a large number of anorexic solder joints on the component side of the glass-epoxy circuit boards. The pcb holes in this amp are plated-through, so these poor-looking connections did not actually manage to cause any problems. Call me crazy, but I want to see nothing but perfect-looking, plump'n'healthy solder joints in a product of this quality.
What listening indeed
The Aleph 3 takes at least an hour to warm up to its final operating state. Both measured distortion and noise are higher when it is cold. Still, the amp…
There is no comparison
I did listening comparisons with my home-built pair of Zen monoblocks. The Zen is also a Nelson Pass design, published in The Audio Amateur in issues 2 and 3 of 1994. It is also a Nelson Pass design, though it was conceived more as a curiosity than as a finished commercial product. The Zen is the only amp in the world with fewer gain stages than the Aleph 3—just a single MOSFET.
I did listening comparisons with my home-built pair of Zen monoblocks. The Zen is also a Nelson Pass design, published in The Audio Amateur in issues 2 and 3 of 1994. It is also a Nelson Pass design, though it was conceived more as a curiosity than as a finished commercial product. The Zen is the only amp in the world with fewer gain stages than the Aleph 3—just a single MOSFET.
To cut to the chase, the Aleph 3 sounded better. There was a definite family resemblance between the two—that friendly coherence that all good single-ended amps seem to convey—but the…
"Desperation is the Mother of Invention." Isn't that how the proverb goes? Certainly it applied ten years ago in the case of the Philips engineers working on the development of the Compact Disc system. Given a specification that had included a 14-bit data word length, they had duly developed a 14-bit DAC chip, the TDA1540, only then to be informed that the CD standard decided upon after Sony joined forces with the Dutch company would involve 16-bit data words. (Thank goodness!)
Philips having already committed the 14-bit design to silicon, they would not have a 16-bit DAC ready in time…