Threshold T-200 power amplifier Page 2

This was confirmed with some simple measurements: in the balanced mode, the voltage at the speaker terminals was down about 9dB at 25Hz compared to 1kHz; in the unbalanced mode, there was no significant difference. Checking with Tom Norton, who had already done the full set of measurements on another sample of the T-200, revealed the reason: in the balanced mode, the T-200 has a measured input impedance of under 1000 ohms—much lower than the typical 30–50k ohms—and the Sonic Frontiers SFL-2 was simply unable to drive such a low input impedance properly. (The T-200's unbalanced input impedance is 49.3k ohms.)

This is an incompatibility, not a defect or design error in either piece of equipment; preamps designed for a low-impedance load would work fine, and the SFL-2 has no trouble driving the more common high-impedance loads, including the T-200 in the balanced mode. However, it does mean that anyone who wants to use the T-200 in the balanced mode had better make sure that their preamp is comfortable with a low-impedance load (footnote 4).

Sound
Perhaps it's ironic, given the difficulty I had driving the T-200 in the balanced mode, but the best word I can think of to characterize the amplifier's performance is balanced. Through changes in associated equipment and in listening to a wide range of music, I was continually struck by the T-200's ability to present music in a coherent, everything-in- proper-proportion manner. This is not to imply that the amp sounded bland or uninvolving—when the recording itself was exciting, the T-200 allowed all the excitement to come through, neither sharpening nor softening timbres or dynamic contrasts.

Midrange neutrality, as judged by the lack of coloration in the reproduction of voices, was excellent. This was especially true when I was using the Dunlavy SC-IVs, which are themselves sufficiently neutral and transparent that they do very little to obscure any problems that may exist upstream. Sylvia McNair's soprano on Sure Thing: The Jerome Kern Songbook (Philips 442 129-2)—one of my 1995 "Records To Die For" picks (Vol.18 No.2)—had a creamy smoothness and a rounded presence that was reminiscent of the real thing.

Spatial and timbral definition were superb, so it was easy to follow the interplay between voice, piano, and double-bass in "Till the Clouds Roll By." The Bryston 7Bs (used in the high-current parallel mode) had a specificity of imaging that matched that of the Threshold, but on this recording, the 7Bs evinced a slight electronic edge that made the voice sound less real, more canned. The Krell KSA-100S had the same sort of "rounded" midrange quality as the Threshold T-200, but I found its dynamics somewhat lackluster in comparison. The T-200 also had better subjective bass extension and drive than the KSA-100S, very nearly matching the Bryston 7Bs in this area. (I have yet to hear an amplifier in my system whose bass performance surpasses that of the Bryston 7B.)

Another of the T-200's major strengths was its reproduction of the treble range. Again, the word that occurred to me in this context was "balance." I want an amplifier to deliver highs that are clean, crisp, smooth, detailed, and extended, but without sounding etched, hard, or clinical. It's not an easy feat, and designers sometimes compensate for the tendency of solid-state equipment to veer toward the hard side by deliberately softening the sound, losing some transparency in the process.

The T-200 managed this delicate balancing act exceedingly well: it sounded smooth, transparent, and extended on top, without sounding in any way hard or "ruthlessly revealing" (footnote 5). Clarity Recordings' recent release of chamber music by Schubert (Trio for Piano, Violin, and Violoncello in E-flat, Op.100; Sonatina in g, Op.134; CCD-1007) illustrated this nicely. In the past, I've felt that some of Clarity's classical releases have not featured musicianship of the highest caliber (their Petrushka comes to mind); but I have nothing but admiration for this recording, which features masterful performances by Edward Auer, Arturo Delmoni, and Nathaniel Rosen. [Me too.—Ed.]

Played through the Threshold T-200 and Dunlavy SC-IVs, each instrument retained its distinctive timbre and maintained its position in space, and there was a good sense of hall ambience. Arturo Delmoni's violin had that characteristic sweetness and suppleness familiar to those of us who've heard him play at various Stereophile Hi-Fi Shows. Rosen's cello had warmth and body, and Auer's piano rang out with bell-like clarity in the upper octaves.

I'm no headbanger, but I do think that some kinds of music have to be played loud in order to be effective; one of my favorite test pieces of this type is Mickey Hart's Planet Drum (Rykodisc RCD-10206). This recording—analog-mastered, but none the worse for it—has startlingly realistic drum sounds and some serious low bass. I played "Temple Caves" at increasing levels until my ears were crying "Uncle," without a hint of protest from the amp or the speakers. (Don't try this at home, kids!) At spl levels measuring above 100dB (Radio Shack spl meter, fast response, C-weighting), the higher power available from the Bryston 7Bs and the Carver Lightstar Reference did demonstrate the benefits of sheer muscle, sounding dynamically more effortless. Audiophiles with large listening rooms and/or insensitive speakers (the Dunlavy SC-IV has 91dB sensitivity), as well as those who routinely listen at high levels, may find that the Threshold T-200 doesn't have quite enough power for their purposes; they would be better off with these other amps—or a pair of bridged Threshold T-200s.

Conclusion
Given the right associated components, the Threshold T-200 can be the centerpiece of an audio system which offers tonal neutrality, precise imaging, and lively dynamics. It gives subjectively equal weight to bass, midrange, and treble, with a high degree of transparency throughout the entire range. Its presentation is neither forward nor laid-back. Although the T-200 is outpointed in certain respects by competing products (eg, the Bryston 7Bs have even greater authority in the bass), the T-200's carefully balanced array of virtues is such that, in my opinion, it crosses the, well, threshold, to Class A.



Footnote 4: The other amplifiers that I'm familiar with that feature a low-input impedance are the ones from the Jeff Rowland Design Group, but the latest versions of these amps have a switch that allows selection of low or high input impedance. Threshold might consider a similar scheme to ensure broader compatibility.

Footnote 5: If Lewis Lipnick, who coined this expression, had copyrighted it and charged $5 every time a Stereophile writer used it, he'd have enough money for a new contrabassoon by now.

COMPANY INFO
Threshold Audio, Inc.
PO Box 41736
Houston, Texas 77241
(713) 466-1411
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Bogolu Haranath's picture

"Stasis" ........... Code 64 :-) ..........

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