Bob Carver

Robert W. (Bob) Carver is an American designer of audio equipment based in the Pacific Northwest.

Educated as a physicist and engineer, he found an interest in audio equipment at a very young age. He applied his talent to produce numerous innovative high fidelity designs since the 1970s. He is known for designing the Phase Linear 700, at 350 W per channel the most powerful consumer audio amplifier available in 1972. He went on to found the Carver Corporation in 1979 and Sunfire in 1994.

Innovative technologies

*Auto-correlator noise reduction (Phase Linear 1000)
*Sonic holography (Carver C-4000)
*Magnetic field coil power amplifier (Carver M-400)
*Transfer function modification (Carver M1.5t)
*Digital Time Lens (DTL) or "Soft eq"
*Asymmetrical charge coupled stereo detector (Carver TX-11 Tuner) — In 1982 Carver created a tuner whose FM stereo detector allowed noise-free reception of much weaker than normal signals. The AM tuner of the TX-11a and TX-11b versions employed a notch filter that demonstrated an AM broadcast can exceed the 15 kHz bandwidth of FM stations without objectionable interference.
*Phase Linear PL-700 (1972)
*Carver M-400 (1980)
*Carver Silver Nine and Silver Seven
*Carver Amazing Loudspeaker (1986) 60 inch full range ribbon plus four 12 inch woofers
*Sunfire Stereo Amplifier
*Sunfire True Subwoofer (1994) 2700 watts and two 8 inch woofers in an 11 inch cube

Amplifier modeling

Carver caused a stir in the industry in the mid-1980s when he challenged two high-end audio magazines to give him any audio amplifier at any price, and he’d duplicate its sound in one of his lower cost (and usually much more powerful) designs. Two magazines took him up on the challenge.

First, "The Audio Critic" chose a Mark Levinson ML-2 which Bob acoustically copied (transfer function duplication) and sold as his M1.5t amplifier (the “t” stood for transfer function modified).

In 1985, "Stereophile" magazine challenged Bob to copy a Conrad-Johnson Premier Five (the make and model was not named in the challenge but revealed later) amplifier at their offices in New Mexico within 48 hours. The Conrad Johnson amplifier was one of the most highly regarded amplifiers of its day, costing in excess of $12,000.

Of note that in both cases, the challenging amplifier could only be treated as a “black box” and could not even have its lid removed. Nevertheless, Bob, using null difference testing, successfully copied the sound of the target amplifier and won the challenge. The "Stereophile" employees failed to pass a single blind test with their own equipment, and in their own listening room. He marketed “t” versions of his amplifiers incorporating the sound of the Mark Levinson and Conrad Johnson designs which caused him some criticism by those who failed to understand the true nature of the challenge — that it was possible to duplicate an audio amplifier's sound in two completely dissimilar designs. In light of this criticism, Bob Carver went on to design the Silver Seven, the most expensive and esoteric conventional amplifier up to that time and duplicated its sound in his M 4.0t and later models which sold for some 1/40th the price (around $600-$1500).

This also started Carver's departure from the M-series amplifier to the more robust and current-pushing TFM series amplifiers. The TFM amplifiers were designed specifically to drive the demanding load of the Amazing ribbon loudspeakers. The apex of Carver's amplifier line was the Lightstar, which is now a collectors item.

Carver also later sued "Stereophile" magazine for their alleged bias against Carver products. ("Stereophile" had first filed suit against Mr. Carver for reprinting the magazine's copyright material without authorization.) The case was arbitrated with neither side awarded damages.

References

The information on Carver products comes from Carver product brochures and manuals. Carver's career has been extensively covered by audio industry magazines including "Stereophile", "Audio", "High Fidelity", and "Stereo Review"

External links

* [http://www.carveraudio.com/ Carver Audio Fan website]
* [http://www.sunfire.com/ Sunfire website]
* [http://www.carverusa.com/ Carver Audio website]

Patents

*US patent|3,727,148 "Amplifier with Protective Energy Limiter Circuit Components", filed January 1972, issued April 1973
*US patent|3,989,897 "Method and Apparatus for Reducing Noise Content in Audio Signals", filed October 1974, issued November 1976 (auto-correlator noise reduction)
*US patent|4,218,585 "Dimensional Sound Producing Apparatus and Method", filed April 1979, issued August 1980 (sonic holography)
*US patent|4,218,660 "Audio Amplifier and Method of Operating Same", filed November 1978, issued August 1980 (magnetic field coil power amplifier)
*US patent|4,309,570 "Dimensional Sound Recording and Apparatus and Method for Producing the Same", filed April 1979, issued January 1982
*US patent|4,415,768 "Tuning Apparatus and Method", filed May 1981, issued November 1983
*US patent|4,4450,95 "Audio Amplifier", filed February 1982, issued April 1984
*US patent|4,457,012 "FM Stereo Apparatus and Method", filed June 1982, issued June 1984 (asymmetrical charge coupled stereo detector)
*US patent|4,484,150 " High Efficiency, Light Weight Audio Amplifier and Power Supply", filed September 1982, issued November 1984
*US patent|4,586,002 " Audio Amplifying Apparatus and Method", filed June 1984, issued April 1986
*US patent|4,808,946 "Lightweight, High Power Audio Amplifier and Power Supply", filed December 1986, issued February 1989
*US patent|4,815,141 "Apparatus and Methods for Removing Unwanted Components from a Communications Signal", filed December 1986, issued March 1989
*US patent|5,748,753 "High Power Audio Subwoofer", filed January 1996, issued May 1998
*US patent|5,937,074 "High Back EMF, High Pressure Subwoofer", filed August 1997, issued August 1999
*US patent|6,166,605 "Integrated Audio Amplifier", filed September 1998, issued December 2000