The key to producing the SPM 650's output power—130Wpc into 8 ohms, 170Wpc into 4 ohms, and 200Wpc into 2 ohms—is Chord's replacement of the usual heavy, bulky power transformers and energy-storing capacitor banks with a compact, lightweight, high-…
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High-tech, compact, and lightweight, Chord's entry-level SPM 650 power amplifier ($4995) promises robust power output, low distortion and noise, flat and ultra-wideband frequency response, and bulletproof reliability—all in what seems an impossibly small package measuring 16.4" wide by 3.4" high by 13.8" deep and weighing only 22 lbs.
Avoiding metal-to-metal contact with the amplifier in attaching TARA's Omega 2 speaker cables, with their large-diameter termination connectors, also proved extremely tricky. Though it was the barrel of the connector and not the conductor that came close to touching the amplifier chassis, I used strips of plastic as insulators rather than risk a short circuit. Admittedly, TARA's connectors are much larger than most, but the tight spacing on the Chord's rear panel will present problems for many other audiophile speaker cables.
Sir Speedy
Do you like fast, tight, effervescent sound?…
Sidebar 1: Specifications
Description: Solid-state power amplifier with switching power supply and linear output stage. Maximum output power: 130Wpc into 8 ohms (21.1dBW) at 0.05% distortion, 170Wpc into 4 ohms (19.3dBW), 200Wpc into 2 ohms (17dBW). Dynamic headroom: 200Wpc RMS into 8 ohms, 360Wpc RMS into 4 ohms. Frequency response into 8 ohms: 0.2Hz–46kHz, –1dB; 0.1Hz–77kHz, –3dB. Voltage gain: 30dB. Signal/noise: better than –103dB, A-weighted, ref. 2/3 power. Output impedance: 0.02 ohm. Output inductance: 2.6mH. Stability: unconditional.
Dimensions: 16.4" (420mm) W by 3.4" (88mm)…
Sidebar 2: Associated Equipment
Analog Sources: Continuum Audio Labs Caliburn turntable with Cobra tonearm & Castellon stand; VPI SuperScoutmaster Reference Rim Drive turntable; Graham Phantom tonearm; Lyra Titan i, Koetsu Coralstone Platinum mono, Shelter 7000 cartridges.
Digital Sources: Musical Fidelity kW DM25 CD transport & DAC, Cary Audio Design CD 306 Professional Version SACD player, BPT-modified Alesis Masterlink hard-disk recorder, Sooloos music server.
Preamplification: Audia Flight Phono, Manley Steelhead phono preamplifiers; darTZeel NHB-18NS preamplifier.
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Sidebar 3: Measurements
To examine the measured behavior of the Chord SPM 650, I primarily used Stereophile's loaner sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com); for some tests, I also used my vintage Audio Precision System One Dual Domain.
My first test of an amplifier is to run it for 60 minutes at one-third its specified power into 8 ohms, which is thermally the worst case for an amplifier with a class-B or -AB output stage. However, the Chord's thermal sensor shut the amplifier down after just six minutes…
When I taught a recording engineering program at a California college, one of my first responsibilities to new students was to clarify for them what recording engineering was really about. Many of them entered the program with the impression that recording was nonstop glamor, with a significant part of the job devoted to partying with their favorite rock bands. It was my job to tell them the bad news: Recording was more about lying on your back underneath a recording console on a dirty studio floor with hot solder dripping on your face.
So it is with reviewing high-end audio products.…
Phono Accessories & Record Cleaners
AcousTech The Big Record Brush: $31.95
This large-handled brush has soft bristles of both natural hairs and conductive synthetic fibers, and makes dusting LPs nearly foolproof. The 5.5"-wide bristle area easily spans the width of any LP's grooved area. Version with ground wire ($46.95) does "a pretty effective job of dissipating static electricity," Mikey said. (Vol.31 No.9)
Acoustic Revive RL-30 Mk.3 record demagnetizer: $2350
The RL-30 Mk.3 removed the high-frequency glaze from harsh-sounding LPs to make a believer out of Mikey. "I…
Power-Line Accessories
Acrolink 6N-NCT 30A Isolation Transformer: $27,500
The expensive dual-transformer 6N-NCT effectively isolates components from the outside world and can also isolate one component from another, allowing users to plug in both analog and digital devices. Adding the 6N-NCT to his suburban system, MF heard a "somewhat deeper, richer, and more solid" sound. A more profound difference might be heard in an urban apartment complex. (Vol.29 No.6)
APC AV S15: $1499 w/battery backup
The S15 is a comprehensive power source, conditioner, and controller that…
Beginning with this issue, Stereophile readers will notice that more of the subjective equipment reviews are augmented with technical reports describing certain aspects of the component's measured performance. Although test data have lately been increasingly included in reviews, Stereophile has recently made a major commitment to providing readers with relevant measurements of products under review. We have just finished building an audio test laboratory featuring the Audio Precision System One, a sophisticated, computer-based audio test measurement system.
"Measurements?", I can hear…
I've been enthusiastically tracking the development of Bel Canto's class-D amplifiers, from their original TriPath-based models to their more recent designs based on Bang & Olufsen's ICEpower modules. With each step, Bel Canto has improved their amps' sound quality and reliability.
Still, two characteristics remained that might be problematic for some listeners. First, the dullness of the upper midrange and lower treble, which I find common in many switching amps, was so reduced in the original Ref1000 monoblock power amp that it was a problem with only a few recordings and/…