The Response Two is one easy speaker for an amplifier to drive, as can be seen from its plot of impedance magnitude and phase (fig.1), which only drops below 8 ohms in the lower midrange. The double hump in the bass is typical of a reflex design, the saddle between the two peaks indicating the port tuning of 47Hz. That the lower peak has a smaller magnitude than the upper one ties in with the rather overdamped alignment. This is due in part to the array of drinking straws in the port, something that has been a feature of Tyler-designed loudspeakers for well over…

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California Audio Labs is a child of the digital age. Originally, they made a noise by offering modified CD players with tube output stages, a practice for which I found no intellectual justification. On the other hand, the results were successful, even if (probably) due to the CAL units' softening of the harshness of early digital sound.
As digital reproduction has matured, CAL (no relation to me) has consistently offered a wide array of well-received digital products, culminating in the CL-10 (Stereophile, Vol.19 No.11) and CL-15 (Vol.21 No.11) CD…
Description: Digital/analog converter with 24-bit/96kHz DACs, 8x-oversampling digital filter, and direct-coupled tube output. Digital inputs: S/PDIF on TosLink and RCA. Frequency response: 5Hz-22kHz, ±0.5 dB. Signal/Noise Ratio: 105dB (A-weighted). Total Harmonic Distortion: less than 0.005%. Maximum output voltage: 2.0V RMS. Output impedance: 2k ohms. Minimum load requirement: 10k ohms. Power Consumption: 18W.
Dimensions: 8.5" W by 4" H by 12.5" D. Weight: 10 lbs.
Serial number of unit reviewed: 22020.
Price: $750 (2000); no longer available (2004).…
Digital sources: Meridian 508.24 CD transport, Meridian 800 DVD/CD transport; Mark Levinson No.360 D/A processor.
Preamplifier: Sonic Frontiers Line-3.
Power amplifiers: McCormack DNA-1 (with Rev.A modifications), Sonic Frontiers Power-2, Power-3.
Loudspeakers: PSB Stratus Gold-i, Revel Ultima Studio, OLS Kharma Ceramique 2.
Cables: Speaker: Straight Wire Maestro II (with PSBs), Harmonic Technology Pro-9 biwire (with Revels), AudioQuest Granite (with OLS Kharmas). S/PDIF digital: Apogee Wyde-Eye, Illuminations D-60. Interconnects, DAC…
The maximum output level of the California Audio Labs Sigma II was 1.92V, a hair under the CD standard's 2V, and it didn't invert polarity. The source impedance was much lower than specified, at a low 24 ohms across the band, but the processor still wasn't happy driving low impedances. The bottoms of the sinewave clipped at -17dBFS into the admittedly punishing 600-ohm load. I wouldn't recommend using the Sigma with a preamp offering less than a 10k ohm load. In addition, when I played the low-frequency raised-cosine signal that I use to diagnose signal polarity…
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M•A M034A (CD only). Todd Garfinkle, prod…
Still, while the Stingray's…
Description: Vacuum-tube integrated amplifier with ultralinear, push-pull output stage. Tube complement, per channel: four EL84s, one 6414, one 12AT7. Line inputs: CD, Video, Tuner, Aux (Record Out, Subwoofer Out available on request). Power output: 50Wpc, optimized for 5 ohm nominal load (15dBW); 25W triode configuration available on request. Damping factor: 10 (equivalent to a source impedance of 0.5 ohms with a 5 ohm load). Bandwidth: 15Hz-40kHz (no limits given). THD at 5W: 0.25%. S/N ratio: 87dB (A-weighted).
Dimensions: 19" W by 6.5" H by 15" D.…
Analog sources: Rega Planar 3, Dual CS 5000 turntables; Grado Reference Master, Ortofon X5-MC cartridges; Audio Refinement AM/FM tuner.
Digital sources: California Audio Labs CL-20 DVD player, Delta CD transport; Audio Refinement CD player, California Audio Labs Alpha 24/96 tube DAC.
Preamplification: E.A.R. 834P tube phono preamp.
Loudspeakers: Celestion A3, Joseph RM22si, Soliloquy 5, PSB Alpha, Cabasse Aria (by Zalytron Industries, designed by Joe D'Appolito).
Cables: Interconnects: Synergistic Research Designer's Reference2 Master Coupler,…