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California Audio Labs Sigma D/A processor

Originally published October 1, 1992

Though their first CD player featured a vacuum-tube output stage, California Audio Labs is recently known for making good-sounding, moderately priced solid-state CD players, like the Icon Mk.II that Jack English reviewed in July 1992 (Vol.15 No.7). The Sigma, a $695 tubed D/A converter, furthers their reputation in both areas.

The Sigma is a straightforward product: no front-panel switches, buttons, or controls. A single LED on the 8¾"-wide front panel indicates that the unit is locked to a digital source. The rear panel has a pair of RCA…

California Audio Labs Sigma D/A processor Associated Equipment

Sidebar 1: Associated Equipment

My reference playback system has remained nearly constant for the past year, providing a stable platform on which to audition and compare digital processors. I auditioned the four processors reviewed in this issue under identical conditions and at matched levels. Additionally, the reference playback system has remained nearly constant for the past year, providing a stable platform on which to audition and compare digital processors. The converters under review fed an Audio Research LS2 line-stage preamplifier, which in turn drove a Mark Levinson No.23.5…

California Audio Labs Sigma D/A processor Measurements

Sidebar 2: Measurements

The Sigma had a rather high output voltage of 3.5V, nearly 5dB higher than the standard 2V output. Output impedance was very high for a 1992 product, measuring nearly 2k ohms at 20Hz, this dropping to just under 1.5k ohms at 20kHz (footnote 1). It was difficult to get an exact measurement of the output voltage into 600 ohms or lower, it dropping as the output stage became current-limited. I noticed on the oscilloscope connected to the Audio Precision System One's monitor output that the waveform was severely clipped when the Sigma attempted to drive a 600 ohm load…

California Audio Labs Sigma D/A processor Specifications

Sidebar 3: Specifications

Description: 1-bit D/A converter with tubed output stage. Tube complement: one 12AX7. Inputs: one coaxial (RCA jack), one optical (TosLink jack). Outputs: unbalanced on RCA jacks.
Dimensions: 8¾" (222mm) W × 4" (102mm) H × 12¾" (324mm) D.
Price: $695 (1992); no longer available (2020). Approximate number of dealers: 96.
Manufacturer: California Audio Labs, Huntington Beach, CA 92647 (1992); Blue Lake, CA 95525 (2000); company no longer in existence (2020).

Looking Back at Fleetwood Mac

I've just recently finished reading guitarist/vocalist Walter Lure's autobiography, To Hell and Back. Walter has a great story about his days in Johnny Thunders's Heartbreakers and his own Waldos. Until he died in late August, you could still hear him playing with the Waldos and running periodic tributes to Johnny. But he also took some space to write about his first band, a hard-rock dance band called Bloodbath that pounded the risers in the North Bronx at the dawn of the 1970s. I had the extreme pleasure of being the vocalist and master of revels in this two-guitar maelstrom. We covered…

AudioQuest Niagara 3000 AC power conditioner

It stands to reason that any audiophile system would benefit from improved AC power. The rooms in most older homes are equipped with a single duplex receptacle on each wall, maybe two per wall in homes employing more modern construction practices. Behind the wall you're likely to find standard 14-gauge Romex, passing through via receptacles that typically sell for about a buck each. The electrical work meets local code, but audiophiles aren't involved in setting local electrical codes.

Another, newer problem is the proliferation of cheap electronic devices. Computers, computer components…

AudioQuest Niagara 3000 AC power conditioner Page 2

The unit has seven rear-panel AC receptacles. Receptacles 1 and 2 are the High Current/Low-Z receptacles intended for power amplifiers; they employ AQ's Transient Power Correction. The remaining five receptacles, for sources, employ AQ's Level-X Linear Noise-Dissipation System; all five source receptacles are isolated from the two high-current receptacles and are broken into two banks, 3–5 and 6–7, which are also isolated from each other. These receptacles are principally intended for connection of source equipment; the manual offers some connection guidelines, but also recommends…

AudioQuest Niagara 3000 AC power conditioner Specifications

Sidebar 1: Specifications

Description: AC powerline conditioner with seven receptacles.
Dimensions: 17.5" (445mm) W × 3.45" (88mm) H × 15.2" (386mm) D. Weight: 24.9lb (11.3kg) net, 33lb (15kg) shipping.
Price: $2995. Approximate number of dealers: 191.
Manufacturer: AudioQuest, 2621 White Rd., Irvine, CA 92614. Tel: (949) 790-6000. Web: audioquest.com.

AudioQuest Niagara 3000 AC power conditioner Associated Equipment

Sidebar 2: Associated Equipment

Analog sources: Pro-Ject Classic SB turntable with Hana SL moving-coil cartridge.
Digital sources: Yamaha BD-A1060 universal disc player; Euphony Audio Summus: Intel NUC-based music server/player/streamer running Roon/Qobuz.
Preamplifiers: PS Audio Stellar Gain Cell preamplifier/DAC; Musical Surroundings Phonomena II+ phono preamplifier with Musical Surroundings LPS.
Power amplifiers: PrimaLuna EVO 300 tube integrated; Bel Canto e1X stereo; Emotiva XPA-1L monoblocks.
Loudspeakers: Magnepan LRS fitted with Magna Riser custom stands; Zu Audio…

Bob Katz on Loudspeaker Isolation

(Photo by Mary Kent)

Of late, Stereophile has written a lot about vibration-isolating footers under loudspeakers. I have been listening to the Magico M-Pods (under the Magico M2 loudspeaker, which won our Loudspeaker of the Year Award for 2020, and which I'll review, in follow-up fashion, in an upcoming issue of this magazine). Following an impressive demo at a 2019 audio show, I also tried IsoAcoustic footers under the Revel Ultima Salon2 loudspeakers. Michael Fremer tried them under his Wilson Alexxes. We both reported positive results.

The idea of isolating loudspeaker…