The Evolution T6's A1 monoblock amplifier doesn't have enough heatsink area to enable it to run at high power for long periods of time. It shut itself down after driving 70W into 8 ohms for 15 minutes, the top of its chassis too hot to keep my hand on. The amp worked fine after cooling down, so owners should make sure they keep the A1 well ventilated. It ran warm during my auditioning but never shut down. The A1's input impedance was 14k ohms unbalanced and 26k ohms balanced, and it didn't invert signal polarity. The unbalanced voltage gain was…
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Sidebar 3: Amplifier/Subwoofer Measurements
Sidebar 4: Loudspeaker Measurements
My estimate of the M6 satellite's sensitivity was to specification at 86dB(B)/2.83V/m. Its impedance plot (fig.13) featured the single bass peak typical of a sealed-box design, this placed at 66Hz, suggesting modest LF extension. Other than minor excursions below 6 ohms in the upper bass and the middle of the midrange, the M6's impedance suggests it is an easy load for an amplifier to drive. The graph is also free of the small wrinkles that would suggest the presence of cabinet resonances. While an investigation of the panels' vibrational behavior…
Although I retain a firm hold on the established audio world, and recognize and value all that it has achieved, I feel inexorably driven to make some space in my life for single-ended amplifiers—more especially, those that eschew negative feedback (footnote 1). A classic if costly example of the art is the Cary CAD-805C, which, to my ears, has earned the right to teach audiophiles what negative feedback really sounds like, and what damage it can do to the musical message when poorly handled. This shouldn't be taken as an out-of-hand dismissal of those many great pieces of electronics and…
When you can hear the originally designed balance of your reference speaker shifted because of the interface with the test amplifier, then life becomes significantly more difficult. Even the Wilson WITT II, whose impedance variation with frequency is remarkably small, was influenced by the Bel Canto SET 80 on its 8 ohm setting. For the record, with the WITT II driven from the ST 80's 8 ohm output, the resulting sound was a little heavy in the midbass, thickened and rounded in the mids, dulled through the presence range, and then tipped-up and glazed in the upper treble. Vocals lost some…
Sidebar 1: Specifications
Description: Single-ended but balanced tube monoblock power amplifier. Output power: 70W into 8 ohms or 4 ohms (18.5dBW, 15.5dBW, respectively). Frequency response: 5Hz–35kHz, –3dB. S/N ratio: 100dB (A-weighted). Distortion: better than 0.05%, –66dB, at 1W (1kHz), predominantly second harmonic. Input impedance: 100k ohms. Input sensitivity: 2V for 30W output. Damping factor: 3 (8 ohms).
Dimensions: 19.5" W by 11" H by 15" D. Weight: 85 lbs.
Serial number of unit reviewed: Not noted.
Price: $6500/pair (1998); gold-plated trim rings, $500; protective tube…
Sidebar 1: Specifications
Specifications: Four-way, bi-wirable, floorstanding loudspeaker. Drive-units: 1", critically damped, dual-chamber metal-alloy dome tweeter with ferrofluid cooling; 4.5" midrange unit with patented, low-diffraction magnet, curvilinear polycone, and ferrofluid cooling; 8", long-throw woofer with curvilinear polycone; 1.5", two-layer voice-coil, and 40oz focused-gap magnet structure; 10" long-throw Acoustic Coupler (sub-bass driver) with dual spider, critically damped cone; 1.5", four-layer voice-coil on a ventilated aluminum former. Crossover frequencies: 35Hz,…
Specifications: Four-way, bi-wirable, floorstanding loudspeaker. Drive-units: 1", critically damped, dual-chamber metal-alloy dome tweeter with ferrofluid cooling; 4.5" midrange unit with patented, low-diffraction magnet, curvilinear polycone, and ferrofluid cooling; 8", long-throw woofer with curvilinear polycone; 1.5", two-layer voice-coil, and 40oz focused-gap magnet structure; 10" long-throw Acoustic Coupler (sub-bass driver) with dual spider, critically damped cone; 1.5", four-layer voice-coil on a ventilated aluminum former. Crossover frequencies: 35Hz,…
Sidebar 2: System
The Vandersteen was auditioned with a Krell KPS-20i CD player used as a transport and feeding a Mark Levinson No.35 D/A converter through a Kimber AGDL digital coaxial cable. TARA Labs Master RSC (unbalanced) connected the Levinson converter to a Rowland Consummate preamp. The primary power amplifier in the system was the Krell KSA-300S. Preamp-to-power-amp interconnects were Monster M1500s or AudioQuest Diamonds (both unbalanced). Loudspeaker cables were either a Monster M1.5 bi-wire or an AudioQuest Midnight/Sterling Hyperlitz bi-wire set (Midnight on the bass,…
The Vandersteen was auditioned with a Krell KPS-20i CD player used as a transport and feeding a Mark Levinson No.35 D/A converter through a Kimber AGDL digital coaxial cable. TARA Labs Master RSC (unbalanced) connected the Levinson converter to a Rowland Consummate preamp. The primary power amplifier in the system was the Krell KSA-300S. Preamp-to-power-amp interconnects were Monster M1500s or AudioQuest Diamonds (both unbalanced). Loudspeaker cables were either a Monster M1.5 bi-wire or an AudioQuest Midnight/Sterling Hyperlitz bi-wire set (Midnight on the bass,…
Sidebar 3: Measurements
JA measured the Vandersteen 3A and provided me with the results after I completed my listening tests and wrote up the results.
JA measured the Vandersteen 3A and provided me with the results after I completed my listening tests and wrote up the results.
The Vandersteen's sensitivity measured lower than specification at an estimated 85dB/W/m (B-weighted). Its impedance is shown in fig.1. The magnitude remains below 6 ohms for much of the range, and dips to a minimum of 2.8 ohms at 35Hz—this, I assume, the tuning of the active acoustic (bass) coupler. This is a moderately demanding load, though the phase angle is low, except in the low bass. The moderate changes due to the various…
The general trend of the midrange and tweeter response is quite linear, though some clearly visible response ripples—particularly from 1kHz to just above 2kHz—would appear to be due to reflections from the cabinet top and its support rods (footnote 2). The sharp peak at about 26kHz is the ultrasonic tweeter resonance.
Fig.3 shows the overall response of the Model 3A averaged across a 30 degree horizontal window (again, measured at 39" from the bottom of the cabinet, 50" away). The bass is down by 6dB at 23Hz, and very flat up to about 500Hz—both excellent results. There is a mild suckout…
The horizontal response family of the Vandersteen 3A, with any on-axis response deviations subtracted out so that the on-axis response appears as flat, is shown in fig.6. That response notch at just below 1kHz deepens at extreme off-axis angles. The overall dispersion through the midrange and top end—making allowances for the small ripples caused by cabinet reflections—is otherwise excellent. The vertical-response family (fig.7) indicates that listeners are better off slightly below the optimum axis than they are above it. Translated, that means that it would be better to err on the side of…