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Don't get me wrong—the Levinson doesn't offer a flattened mid-fi stage. The horns on J. Gordon Holt's Praeludium recording on the original Stereophile Test CD are still set well back in the image, as indeed they should be. But it is possible that the No.23.5's somewhat more vivid balance overemphasizes recorded detail to the detriment of its depth presentation. Whether it is more or less accurate in this behavior is hard to determine with an electronic recording. However, those who desire the deepest of all possible soundstages should mate the 23.5 with loudspeakers that already excel in…
Sidebar 1: Specifications
Description: Solid-state stereo power amplifier. Rated power output: 200Wpc continuous into 8 ohms (23dBW) with less than 0.1% THD, 400Wpc continuous into 4 ohms (23dBW) with less than 0.2% THD, both from 20Hz–20kHz, both channels driven. Damping factor: greater than 600 at 50Hz, 8 ohms (equivalent to an output impedance of 0.013 ohms). Frequency response: 4Hz–140kHz, —dB. Input impedance: 50k ohms shunted by 1.5nF. Voltage gain: 26dB (load not defined). Input sensitivity: 141mV for 1W output.
Dimensions: 19" (483mm) W by 8.25" (210mm) H by 15.7" (399mm) D.…
Sidebar 2: Review System Context
Loudspeakers used during the evaluation of these amplifiers were mainly the Wilson WATTs and Puppies and KEF R107s, though Avalon Eclipses, Acoustat Spectra 1100s, MB Quart 490s, and Epos ES11s also made appearances. Front-end components consisted of a Linn Sondek/Lingo/Ekos/Troika setup sitting on an ArchiDee table to play LPs, a Revox PR99 to play 15ips master tapes, and, at various times, a Meridian 208 CD player, the Stax DAC-X1t and VTL Reference D/A processors driven by Meridian 602 and Wadia WT-3200 transports, or the Krell MD-1/SBP-64X combination…
Sidebar 3: Measurements
One of the things that distinguishes expensive power amplifiers from the rest is that they rarely break or shut down on the test bench, even when driving 2 ohm loads at high levels at high frequencies. Such was the case with the No.23.5, which proved a powerhouse. With one channel driven, it comfortably exceeded its 23dBW power specification, the 1% distortion point being reached at 305W into 8 ohms (24.8dBW), 505W into 4 ohms (24dBW), and 750W into 2 ohms (22.7dBW), this behavior shown graphically in fig.1. With both channels driven, these figures dropped…
Brian Tucker, the US Quad importer, introduced me to the Woodside MA50 tube amplifiers and their manufacturer, John Widgery, during the 1992 Summer CES. Tucker's combination of Woodside MA50 tube amplifiers and Quad ESL-63 USA Monitors sounded unusually neutral, dynamic, and detailed. This was good news; back in 1987, Dick Olsher (Vol.10 No.6, pp.104–5) was unable to recommend an earlier Woodside-manufactured amplifier, the Radford STA 25 Renaissance. Brian mentioned that the MA50's design is a much-improved version of that earlier Radford model. Time for another review.
Some history…
Unscrewing four Phillips-head fasteners allows the cover to be lifted. From the front, the toroidal AC transformer and printed circuit board (pcb) are positioned at chassis right, while the output tubes and large E-I audio output transformer are on the left. Both transformers employ solder tags, rather than flying leads. This means Woodside can choose better wire; in this case, silver. The tube sockets are not attached to the circuit board. This prevents tube-generated heat from aging the solid-state components, but point-to-point wiring is needed to connect the pcb with the tube sockets.…
Sidebar 1: Specifications
Description: Tubed monoblock amplifier using four EL34 tubes in the output stage. Rated output power: 50W minimum continuous sinewave power into 8 ohms at 1kHz (17dBW), with no more than 0.2% THD; 75W minimum continuous sinewave power into 4 ohms at 1kHz (15.75dBW), with no more than 0.2% THD. Dynamic headroom: 1.6dB. Peak output current: 15A. Frequency range: 8Hz–56kHz. Input impedance: 100k ohms. Sensitivity: 750mV (equivalent to a voltage gain of 28.5dB). Slew rate: 15V/µs. Power consumption: not given.
Dimensions: 9" (220mm) H by 16.8" (420mm) W by 10.8…
Sidebar 2: System & Setup
My listening room measures 26' long, 13' wide, with a 12' semi-cathedral ceiling. An 8' high by 4' wide doorway at the back of the room opens into a kitchen, adding an additional 25' by 15' area. I also used a second listening room, 17' by 10', to audition the MA50s.
I compared the Woodsides with a Mark Levinson No.27.5. Additional gain-matched listening tests were conducted with a Krell KSA-250. Because its power ratings are twice that of the Woodsides, sonic comparisons with the Mark Levinson focused on low-frequency extension, imaging, soundstage…
Sidebar 3: Measurements
The Woodside MA50's chassis was hot over the output tubes following the 60-minute, 1/3-power preconditioning, but no more so than the typical tube amplifier. Its input impedance measured just over 92k ohms, its voltage gain into 8 ohms, 29.7dB. The Woodside is non-inverting; a positive-going input results in a positive-going output. S/N ratio measured an excellent 110dB (unweighted, 22Hz–22kHz referenced to 1W output into 8 ohms). The amplifier's DC offset was unmeasurable, as is almost always the case with transformer-coupled designs.
The Woodside's output…
I had been sent a sample of the Woodside SC26 tube preamplifier during my June 1994 review of Woodside's MA50 monoblock amplifier (Vol.17 No.6). Although I used a number of preamplifiers during that review, I was most impressed with the MA50s' spacious, three-dimensional soundstage when driven by the SC26. At the time, I had an impression that the SC26's sonics combined a midrange richness with a good dynamic range. Although I had to return the Woodside MA50s to the importer after I reviewed them, I continued listening to the SC26.
Description
The SC26 looks functional and slim. The…