search
The only reason for testing the SK-5A with an actual cartridge source was to determine how the unit handles the spurious material unique to disc reproduction: the ultrasonic pulses stemming from slight (or less than slight) groove mistracking. In this area, the SK-5A acquitted itself superbly, adding no perceptible roughening or exaggeration of the pulses. The preamp's front end is, by the way, extraordinarily quiet. With my Ortofon cartridge, however, whose 0.05mV output is by far the lowest of any MC, hum was barely audible at normal, moderately high listening levels, but the hiss level…
Sidebar 1: Review System
For testing the SK-5A, I used what has been my reference system for the past six months or so: an Ortofon MC-2000 cartridge (with and without its own step-up transformer), the Well-Tempered Arm, the SOTA Star Sapphire turntable, Sony's 650 and 703 CD player/converter combo, an Audio Research SP-11 preamp, a pair of the mono Threshold SA-1 power amplifiers, and a pair of Sound Lab A-3 full-range electrostatic speakers.—J. Gordon Holt
Sidebar 2: Specifications
Description: Solid-state stereo preamplifier. Inputs: Phono, Line, Aux, Tape. Controls: Source, Mode (Tape Monitor, Tape Source, Mono), Balance, Volume, Phase (Invert, Mute, Normal). Gain: Phono 22–34dB; Line 14–20dB. Bandwidth: MC phono 1Hz–150kHz; MM phono and Line inputs, 0.5Hz–250kHz. Output impedance: 300 ohms.
Dimensions: 19" W by 2.5" H by 12.5" D. Weight: 12 lbs.
Price: $3250 (1987); no longer available (2007). Approximate number of dealers: undisclosed.
Manufacturer: Klyne Audio Arts, Olympia, WA 98501. Tel: (360) 273-8477. Fax: (360) 273-6991…
This product is a pre-trol. What, you may well ask, is a "pre-trol?" Well, Threshold Corp. calls its FET-10 a preamplifier, but it isn't, really. In fact, it isn't an It at all; it's a Them. Only half of Them is a preamp, and you can buy each half separately. If that sounds a little confusing, maybe it's because some of the old, familiar language of audio is starting to lose its relevance.
Once upon a time, in the dark ages before magnetic pickup cartridges, that part of an audio system that controlled everything—input switching, volume, bass and treble—was called the control section.…
Since the Klyne report is slated to appear in the same issue as this review, I refer you to that for a discussion of how I feel about cartridge matching. But it's been a while since I explained my feelings about bypass testing of preamps.
Listening
It is much easier to assess the accuracy of a preamplifier than it is to evaluate a power amp. As I mention in my report on the Mirror Image 1.1S power amp (also in this issue), the problem with a power amplifier is that you can't listen to it without using a loudspeaker. And since you can't listen to a loudspeaker without an amplifier,…
JGH returned to the Threshold FET-10 in January 1988 (Vol.11 No.1):
The more I listen to this two-piece RIAA preamp/line controller, the more convinced I am that it is a, if not the, state-of-the-art preamplifier. It is, at least, the most nearly perfect such device I have tested, or read about elsewhere. In fact, since it arrived here, Dick Olsher and I have come to trust its accuracy so much that we had endless squabbles about who would get to use it when for testing other components. Neither of us felt we could do without it. We finally ended up ordering a second one—one of the very…
Sidebar: Specifications
Description: Dedicated line-level and phono preamplifier units. FET 10/H: Line-level control center. Inputs: Analog Disc (Phono to you, fella!), Auxiliary, FM/AM Tuner, CD Player, Video Audio, 2 Tape Monitors. Outputs: 2 Tape Record, Main to power amp. Controls: Source, Mode (Stereo, Reverse, Invert, Mono), Signal Distribution (Monitor Tape 1 or 2, Copy 1 to 2, Copy 2 to 1), Volume, Balance. Voltage gain: 20dB max. Frequency response: 1.5Hz–150kHz +0, –3dB. Max output: 20V. THD: 0.01% at 1V out. Output impedance: 100 ohms. FET 10/P: Phono preamplifier/RIAA…
Thiel Audio, headed up by Jim Thiel (President and chief designer) and Kathy Gornik (Marketing Director), sets itself apart from other speaker manufacturers not only by making what I feel to be almost uniformly excellent products, but also by serving as a kind of hallmark for the good dealer: Although not all good dealers sell Thiel, just about every Thiel dealer is a good one. This comes about because, in spite of just about uniformly positive reviews and excellent customer relations, Thiel (primarily in the person of Ms. Gornik) has insisted on limited distribution through retailers they…
One of the advances claimed by Thiel in the '1.2 comes from a redesign of the woofer to include a copper ring around the pole-piece, a practice Thiel originally used for the '3.5 woofer. This is said to maintain stability in the flux of the permanent magnet which is a part of all moving-coil drivers. This flux density has a tendency to "sag" in response to the work needed to move the woofer cone, and the copper ring—through a complicated electromagnetic interaction I couldn't quite understand and certainly can't verify—compensates for this sag. Impressively flat resulting flux-density…
Sidebar 1: Phase Coherence
Phase coherence is a subject every bit as complex as loudspeaker waveform radiation. Purists such as Thiel maintain that their 6dB/octave slopes are the only way to truly maintain phase coherence; John Bau of Spica can show you on his Tecron analyzer that the Bessel 4th-order low-pass filter he uses to cross his tweeter down to the woofer on his TC-50 and Angelus, when used with the particular drivers he chooses, is also phase coherent.
Not mentioned by any of these designers, but surely important, is that the loudspeaker radiation is phase coherent and…