Spaced Omnis & the Curtain of Sound
If directional information can be represented by interchannel time delays, then would it be possible to abandon Blumlein's "amplitude for phase difference" substitution outlined last month and concentrate on the time delay information? About the time that Blumlein was experimenting with his crossed figure-of-eights in 1931, the Bell Telephone Labs in the USA derived from experimental binaural work the "curtain of sound" concept (fig.7). The overall wavefront emanating from the orchestra is sampled at a large number of coplanar points. The signals…
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An Audio Obstacle Course: The Shure Trackability Test Record
Shure Bros. TTR-101.
Shure Bros. TTR-101.
Shure's new "Supertrack" V-15 Type II pickup was designed as an answer to all those high-powered discs whose excessive modulations make them shatter all over the place on lesser pickups, But just in case anyone didn't happen to own any of these difficult discs, Shure decided to issue one of these, too. The result is a collection of some of the meanest modulations ever gathered together in one place.
Each "test" is a series of four short musical excerpts, recorded at progressively higher levels…
When it comes to amplifiers, ya gotcher tubes, yer solid-states, and yer hybrids. Although amplifier manufacturers would have you believe otherwise, the majority of designs within each category are variations on a few fairly-well-known themes. Everyone agrees that the power supply is extremely important. Most designers try to obtain the amplifier's desired frequency response and distortion characteristics with a minimum of negative feedback. It's also agreed—at least among designers of solid-state amps—that the ability to drive a variety of speakers, including those that present a low-…
I was ready for some serious listening. I went through the usual test pieces (Chesky, Reference Recordings, etc.), and also listened to some "ordinary" records that I just happened to feel like playing. The sound was impressively neutral, the amp doing little to call attention to itself—which is just what you want it to do. With the Lightstar in the system, I was content to listen to the music, and felt little urge to switch over to one of the other amps I had on hand (all of them more expensive). This, too, is a sign that an amplifier is doing something right.
Dynamics and a sense of…
Sidebar 1: Carver the Man & Carver the Company
For the benefit of those Stereophile readers who aren't fully up on industry scuttlebutt, here's the real scoop (or at least as much as I know) about Carver the Man and Carver the Corporation: Bob Carver founded Carver Corporation in the early 1980s and was its CEO for a number of years, eventually taking the company public. About two years ago, he left the Corporation on a year-long sabbatical, and ended up resigning in March 1994. There were suits and countersuits about financial matters, non-competition clauses, and patent rights.…
Manufacturer's Comment, March 1995
Editor: In spring of this year I wrote you to answer many questions which had been posed to us about the departure of Robert Carver from Carver Corporation, and the subsequent legal disputes that occurred. I am pleased to inform you that these disputes have now been settled, and in a manner that is very satisfactory to the company. The essential elements were reported in a letter to our shareholders as follows:
1) Both parties have mutually released any and all claims brought against the other party in the lawsuit.
2) Beginning in 1995…
Sidebar 2: Carver Research Lightstar Reference: Design
The Carver Lightstar Reference is a power amplifier whose ratings suggest that it is an ideal voltage source—meaning that its rated power doubles with each halving of load impedance (300W into 8 ohms, 600W into 4 ohms, 1200W into 2 ohms). That's difficult to accomplish with conventional power transistors, which operate safely only within a restricted range of voltage/current combinations. (The graph of this range is called the transistor's safe operating area.) Many amplifiers deal with this limitation by using several transistors…
Sidebar 3: Review System
Analog sources were the Linn Sondek LP12 with all the accoutrements (Lingo, Cirkus, QR/DNM Design 330 Mk.II Ringmat), Linn Ittok, and AudioQuest AQ7000nsx. Digital sources were PS Audio's Lambda transport, Sonic Frontiers' UltraJitterbug, PS Audio's UltraLink II, and Sonic Frontiers' SFD-2. The preamp used was mostly a Sonic Frontiers SFL-2, with some use also made of a Convergent Audio Technology SL-1 Signature. Reference power amplifiers were the Bryston 7B monoblocks, Krell KSA-100S, and Threshold T-200.
Interconnects, digital links (AES/EBU), and…
Sidebar 3: Measurements
A full set of measurements of the Carver Lightstar was made in its unbalanced mode, with selected measurements repeated for the balanced configuration. Unless otherwise noted, the results below are for unbalanced operation. Also, all measurements (except for the gain check) were made with the normal gain setting.
Following the 1/3-power, one-hour preconditioning test, the Lightstar's heatsink/chassis was too hot to touch comfortably for more than a few seconds.
The Lightstar is non-inverting in the unbalanced mode. Balanced, pin 2 is configured as…
Sidebar 4: Specifications
Description: Solid-state stereo power amplifier. Power output: 300W into 8 ohms (24.8dBW), 600W into 4 ohms (24.8dBW), 1200W into 2 ohms (24.8dBW). Frequency response: 20Hz–20kHz ±0.5dB. Full power bandwidth: 10Hz–20kHz. Channel separation: >60dB at 1kHz. Output impedance: ±0.04 ohms. Damping factor: >200, equivalent to an output impedance of less than 0.04 ohms. THD: <0.2%. Signal/noise ratio: low gain, 107dB; high gain, 98dB (A-weighted, referenced to rated power); low gain, 82dB; high gain, 73dB (A-weighted, referenced to 1W). Slew rate: >50V/µs.…