Comparisons
First up to the plate was the TLC-1's obvious competitor: its passive ancestor, the Mod Squad Line Drive Deluxe—for quite a while my reference for preamplifier non-signature. To my surprise, the Line Drive was more colored than the TLC-1 in its passive mode, its midrange sounding somewhat "squawky" in comparison. It also sounded more veiled, with less top-octave air. Dynamics and bass performance were about the same, however. When I used the TLC-1's buffered outputs, the difference was larger. There was a slight loss in space and image palpability, but the sound otherwise…
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Sidebar 1: Specifications
Description: Solid-state, unity-gain stereo preamplifier with five line inputs and two tape loops. Measured frequency response: ±10Hz-200kHz, -0.25dB. Measured input sensitivity: 1.02V RMS for 1V output. Measured S/N ratio (unweighted ref. 1V output at 1kHz): 108/112dB (L/R). Input impedance: approximately 13k ohms. Output impedance: buffered, 250 ohms; passive, varies with volume-control setting; tape, 100 ohms. Maximum output: 12.5V RMS. Absolute polarity: non-inverting.
Dimensions: 19" (483mm) W by 11.75" (299mm) D by 2.625" (67mm) H. Shipping weight: 11…
Sidebar 2: System
The main comparison preamplifier was the Melos SHA-1 headphone amplifier used as a line-stage (footnote 1), while the Mod Squad Line Drive Deluxe and the Classé Six reviewed by Larry Greenhill in February (footnote 2) also saw some action. Power amplifiers included the YBA 2 HC, Mark Levinson No.20.6es, and Audio Research Classic 120s. Loudspeakers used during the review period included the B&W Silver Signatures, Velodyne DF-661s, and Green Mountain Diamantes.
Front-end components were a Linn Sondek LP12 (Cirkus/Trampolin/Lingo)/Ekos/Arkiv setup sitting on…
Sidebar 3: Measurements
The TLC-1's measured gain was actually a little less than unity, at -0.15dB. Its input impedance was a moderate 12.25k ohms with the volume control set to its maximum position, while the source impedance from the buffered outputs was a whisker under 70 ohms. The buffered tape outputs featured a 101 ohm impedance, while from the passive main outputs, the source impedance varied from 26 ohms with the volume control set at its maximum position, to around 1700 ohms with it set to 12:00 (when the gain is approximately -16dB). DC offsets were unmeasurable, and the TLC-1…
As you may have noticed, Stereophile's approach to equipment testing is quite different from that of "mainstream" audio publications. Instead of throwing a bunch of measurements at you, and telling you how we think components ought to sound because of those measurements, we test them as you would: by listening. But we have an extra problem: we have to convey to someone else—you—a feeling for what we hear from that component. It ain't always easy.
Many letters we receive express bewilderment and irritation with some of our terminology. This seems to imply that our equipment reports don't…
Most speakers don't come in heavy wooden crates—they come in cardboard cartons, two per box, light enough to be tucked under one arm and carried out to the car. Not so in HighEndLand, where the smallest minimonitor can test a healthy man's strength. There are plenty of good reasons for this cult of robustness, foremost among them structural stability and the suppression of resonances.
At 4½' tall and 154 lbs (70kg) each, PBN Audio's Montana EPS exemplifies extremism in the pursuit of solidity. Rap as hard as you will anywhere on the hexagonal cabinet—go ahead, bust your knuckles—…
But I'm too cautious to try something like this without setting it up on the test bench first—if you've ever accidentally smoked an amplifier by misconnecting its output, you'll know why. In biamping with two unlike amplifiers, you can't be sure that their outputs are in phase with each other, or if they "track" in a similar fashion—that is, produce equal output voltages for equal inputs. My test procedure was to put the AudioPrism and the Parasound HCA-1000A I intended to use side by side and feed them the same frequencies (from a Leader sinewave generator) while monitoring their outputs…
Sidebar 1: Specifications
Description: Three-way, reflex-loaded, floorstanding loudspeaker. Drive-units (all ScanSpeak): one 1" fabric-dome tweeter, two 4" Kevlar midrange cones, two 8" woofers. Crossover points: 300Hz, 3kHz. Crossover slopes: 24dB/octave. Frequency response: Not specified. Sensitivity: 92dB/2.83V/m. Impedance: 4 ohms (3–11 ohms).
Dimensions: 53.75" H by 14.25" W by 15" D. Weight: 154 lbs. (70kg) each.
Finishes: approximately 20 natural wood veneers; lacquer on special request.
Serial numbers of units reviewed: 97357, 97358, 970326, 970327.
Price: $7995/pair…
Sidebar 2: Associated Equipment
Analog source: Well Tempered Reference turntable with Sumiko SHO cartridge.
Digital sources: Melior by Museatex and PS Audio Lambda 2 CD transports; Randy Tomlinson–modified JVC XLZ-1010, Marantz CC-48, and Marantz CC-65SE CD players; Parasound D/AC-2000 and Theta DS Pro Basic III DACs; Genesis Digital Lens.
Preamplifiers: Threshold T-3i, Cary SLP 94P, Audio Research SP14, Parasound P/LD-2000, Creek OBH-12.
Power amplifiers: Threshold T-100 (as monoblocks), Parasound HCA-1000A, AudioPrism Debut Mk.II, Cary Audio 805c.
Cables: Nordost SPM,…
Sidebar 3: Measurements
The big Montana was among the more sensitive speakers I have measured, at an estimated 92.5dB(B)/2.83V/m. As BW found, it won't need many amplifier watts to play loud. However, the partnering amplifier needs to have good current capability, as the impedance (fig.1) drops to 3 ohms or below for much of the bass and midrange regions. Thankfully, the phase angle is low over most the audioband.
Fig.1 PBN Montana EPS, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)
Despite its large panels, the well-braced cabinet is…