Waveform Research Mach 17 loudspeaker Reference system
Listening tests were carried out in my main listening area—a spacious, 5500ft3 room with an effective length of 51', a width of 13', and a height of 12', in a wood-frame house with only moderate masonry infill. The room has only one area rug, making it a live listening environment, while its generous length supports low bass, with reinforcement from the side and back walls. Previous reviews describe this large room's construction, exact dimensions, contents, listening positions, rugs, windows, reverberant character, and bass modes (see March 1992, Vol.15 No.3, p.181).
The system was controlled from a Krell KBL preamplifier (now discontinued). Not having a pair of Bryston 5B-STs available, I used two different combinations of solid-state stereo amplifiers for this review. Two Bryston 3B-STs stereo amplifiers (treble and midrange) were used with a pair of Bryston 7B-STs (for the woofer drivers). This amplifier trio provided six channels, each rated at 2V sensitivity, to reach maximum output. My other combination retained the 7B-STs (requiring 2V for full balanced output) for the woofers, but substituted two slightly more sensitive Mark Levinson stereo amplifiers (1.4V required for full output) for the two Bryston 3B-STs: a No.27 (now discontinued) for the treble and a No.331 for the midrange. To promote better matching of gain between the 7B-ST and the Levinson amplifiers, I advanced the electronic crossover's bass-level control to +2dB.
The comparison loudspeaker system was the Snell Type A Reference system using single-ended cables. The Snell's huge subwoofers permitted me to establish a bass "reference" in the listening room.
Use of the Mach 17 loudspeaker meant switching to balanced connections. For this purpose, connections were made with XLR-tipped balanced cables made by Krell (Cogelco Yellow), Bryston, and Madrigal. Bi-wired OCOS speaker cables from Sumiko were used for the midrange section, Mark Levinson speaker cable for the midrange, and Monster speaker cable for the Mach 17's subwoofers.
Other associated equipment included a Day Sequerra FM Reference tuner, a Rotel RHT-10 FM tuner, and a Linn Sondek LP12/Lingo turntable, Ittok arm, and a Spectral moving-coil cartridge. CDs were played on a Krell MD-1 turntable, which drove an Audio Alchemy DTI jitter attenuator using a 75 ohm Silver Starlight digital coaxial cable. This unit fed either an Adcom GDA-700 D/A processor or an Audio Alchemy DDE v3.0 HDCD D/A processor over its I2S bus. This converter was fitted with an RW-1 Remote Wand One.—Larry Greenhill