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,…
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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.
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…
Sidebar 2: Measurements
Fig.1 shows the plot of impedance with frequency for the Thiel CS1.2. It agrees with the appropriate specified impedance in the review heading, but it is noteworthy how little change there is for each speaker. Obvious features can be distinguished, such as the port tuning, but I would conjecture that Jim Thiel has used some form of conjugate load system in his crossover designs to give such a flat curve with frequency. (This is where elements are added to the crossover to compensate for phase and impedance changes to result in a simple resistive load.) I would…
Sam Tellig wrote about the Thiel CS1.2 in June 1989 (Vol.12 No.6):
At $1090/pair these speakers have a lot going for them. They look great—elegant styling, impeccable cabinet finish. (The speaker terminals under the cabinet are a pain in the ass if you like to experiment with changing cables, though. You have to pick up the speaker, turn it on its side to switch cables. With this arrangement, though, you can hide some cables under the carpet, and bring them up under the speakers through a little hole in the rug. "Look, dear, no cables!")
When I first got the Thiels, I was…
John Atkinson wrote about the Thiel CS1.2 in November 1989 (Vol.12 No.11):
You will probably remember from October's "Recommended Components" that there was disagreement in Stereophile's ranks over the merits of the smallest in Thiel's range of three loudspeakers, the CS1.2. Larry Archibald had been mightily impressed with the sound of this $1090/pair floorstanding speaker last January, feeling that it "images extremely well, has a more extended...and more natural high end [than the similarly priced Spica Angelus]...plays reasonably loud easily, has satisfying low-end extension, and…
Sidebar: November 1989 Measurements:
Before listening to each pair, I ran a series of measurements on all four speakers to see if there was any obvious reason for the conflict of opinion. Fig.1 shows the spatially averaged in-room response of Larry's pair, a curve that correlates quite well with the subjective tonal balance. Though a slightly overdamped alignment leads to the response starting to roll off below 80Hz, it still features useful bass output down to 42Hz, the frequency of the bottom E string of the double bass and bass guitar. While the '1.2 does not compete with the Waveform…