Larry Greenhill

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Larry Greenhill Thomas J. Norton Posted: Sep 02, 2010 Published: Oct 02, 1984 0 comments
James Bongiorno, the engineer behind the Sumo Andromeda, has enjoyed a long and colorful career as an audio amplifier designer. He has cast himself at times as an enfant terrible, exploding at audio critics and running scandalous advertisements (footnote 1). His best-known amplifier is the Ampzilla, produced by Great American Sound, but he also designed the Dyna 400. Currently Jim is living on a boat and serving as part-time consultant to the Sumo Company.
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Larry Greenhill Posted: Aug 20, 2008 0 comments
With the popularity of home-theater systems, subwoofers have proliferated. Because multichannel AV receivers are designed to provide a properly filtered, line-level subwoofer, or low-frequency effects (LFE) signal, many subs no longer come with built-in high- and low-pass filters for insertion into two-channel audio systems. However, the PB13-Ultra subwoofer from SV Sound does include these, which is what piqued my interest in it. After Ed Mullen, SV Sound's director of sales, assured me that the PB13-Ultra was capable of reproducing solid 20Hz organ-pedal notes in my listening room, I asked for one to review.
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Larry Greenhill Posted: Jan 12, 2008 0 comments
"We don't have a price yet, because the TAD Compact Reference One Monitor loudspeaker is a prototype," stated Andrew Jones, lead engineer for loudspeakers at TAD Laboratories, Inc., shown here in John Atkinson's photo. "I can say that it will be somewhere between zero dollars and $60,000, the cost of a pair of our full-sized TAD Reference One speakers."
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Larry Greenhill Posted: Jan 14, 2013 3 comments
I ran into Dan D'Agostino, in the hallway of the Venetian. He was hurrying off to a meeting, but had a moment to mention that his amplifiers were being used in live exhibits in several rooms, including YG and Light Harmonic DaVinci, among others. I asked if there was anything new at the show, and he smiled and mentioned the new Momentum preamplifier. I found the D'Agostino room and his partner Petra, showed me the preamplifier, which was on passive display.
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Larry Greenhill Posted: Jan 13, 2010 1 comments
John Devore was using this diminutive integrated amplifier, the German-manufactured Acoustic Plan Mag Amp, to drive his new high-sensitivity loudspeakers. According to Jonathan Halpern, the US importer, the Mag Amp uses a tubed voltage-gain stage and an output stage comprised of two small transformers with dual primaries. He described it as the "world's first switching integrated amplifier, and added that it was designed by Lars Lundahl in the 1960s. The 19 kg stereo chassis offers 15Wpc into 8 ohms and will cost $18,500. It played both a 1980s recording of Ella Fitzgerald and one of Stravinsky's Pulcinella Suite with great dynamics, speed, and detail. This is the kind of odd and fascinating gem one can uncover at the end of a day when one is too tired to rush out of an exhibit room, and instead collapses on the couch to listen.
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Larry Greenhill Posted: Jan 16, 2012 0 comments
Harman Specialty Audio introduced the new Revel Performa 3 series of loudspeakers at the 2012 CES. Kevin Voecks, lead audio engineer in the design, was delighted at the increased performance of Performa 3 series, including the $4500/pair, three-way, F208 full-range floorstander and the $1750/pair M106 two-way bookshelf. The F208 replaces the more expensive, $7500 F32 Performa in the previous series.
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Larry Greenhill Posted: Jan 12, 2008 0 comments
"The technology to create a full, wireless, 5.1 channel audio system simply wasn't available before, "said Mike Gough, B&W's Senior Project Manager on the Liberty System, "so we waited until it was possible to do it right." The Liberty employs a proprietary, robust wireless protocol with channel switching capabilities—called dynamic channel selection—to avoid interference from existing WiFi networks. Its wireless transmitter broadcasts 8 separate channels, allowing for full 5.1 in one room, and a stereo setup in a second room. Alternatively, the Liberty can support 4 separate stereo zones throughout the house.
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Larry Greenhill Posted: Jan 12, 2008 0 comments
"The technology to create a full, wireless, 5.1 channel audio system simply wasn't available before, "said Mike Gough, B&W's Senior Project Manager on the Liberty System, "so we waited until it was possible to do it right." The Liberty employs a proprietary, robust wireless protocol with channel switching capabilities—called dynamic channel selection—to avoid interference from existing WiFi networks. Its wireless transmitter broadcasts 8 separate channels, allowing for full 5.1 in one room, and a stereo setup in a second room. Alternatively, the Liberty can support 4 separate stereo zones throughout the house.
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Larry Greenhill Posted: Jan 13, 2012 0 comments
Each Xs channel has two chassis, one for the power supply and the other for signal amplification. The amplifier acts as a voltage source, and is rated at 300W into 8 ohms, 600W into 4 ohms, and 1200W into 2 ohms. It is biased to ensure make certain that the amplifier remains in class-A mode into all loads. Each channel has 122 output devices with a total rating of 10kW, and the extensive heatsinking allows the Xs 300 to deliver 2kW into a load "all day long." Though the Xs 300 stack was a silent exhibit, the company was using the more modest $65,000/pair Xs 150s to drive the Pass Lab RM2 loudspeakers, which showed a wide dynamic range and outstanding detailing.
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Larry Greenhill Posted: Jan 16, 2012 0 comments
Ron Sutherland of Sutherland Engineering taught me all I need to know about Nixie tubes at CES. Used as the main visual display device used in his Reference N-1 preamplifier and in his Destination Line-Stage preamplifier's control unit shown in the photo, the Nixie tube was invented in 1955 as the first electronic display tool for reading out the numbers 0–9. The Nixie's designers fashioned a wire mesh into 9 layers, each layer in the shape of a number, resulting in a tidy small stack. This tiny wire stack was inserted into a small glass envelope, filled with neon gas, and then sealed. When any of the separate metal layers was charged with 175 volts, the neon gas around the wire ionized, and lit up. When plugged into a circuit board, the tube would read out the numbers, with each number appearing at a different depth. Paul was fascinated with the retro look of this type of readout, so he has installed it in his $15,000, three-chassis Destination line stage, and into his new $10,000 reference N-1 preamplifier.

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