And the more time I spend making real music, the less I'm impressed with home…
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It's always good to have a reference. No matter the endeavor, references help guide us and set standards for all we do. For many hours of every day, I'm lucky to enjoy the reference of live, unamplified music. Right now, I average over 20 hours a week of rehearsals and performances of various ensembles, and four to five hours of listening to recorded music on my hi-fi. Clearly, for me, my musical reference is not the sound of my audio system, but the sound of live music created in various venues and acoustics.
I first listened to the Ref150 with its stock power cord plugged straight into the wall, then into a Shunyata Research Hydra 8 power conditioner. The ARC sounded significantly more dynamic and open plugged into the wall; the Hydra 8 obscured the amp's drive and punch in a very obvious way. I then replaced the Ref150's stock cord with a 20A cord used in-house by ARC and designed by Sain Line Systems, the maker of most of my cables. The Sain cord was a definite step up in every way, reducing the grain structure of the sound, extending and sweetening the treble, fleshing out the midrange, and…
Sidebar 1: Specifications
Description: Tubed stereo power amplifier. Tube complement: eight KT120 (matched pairs, output), four 6H30 (driver). Input: Balanced, pin 2+ (IEC-268). Output taps: 16, 8, 4 ohms. Power output: 150Wpc (21.75dBW) continuous, 20Hz–20kHz into matched load. Approximate actual power available at clipping: 160W. Power bandwidth: 5Hz–80kHz, –3dB. Frequency response: 0.5Hz–120kHz, –3dB at 1W. THD at 1kHz: typically 0.6% at 150W, <0.03% at 1W. Input sensitivity: 2.0V RMS for rated output, Voltage gain: 24dB into 8 ohms. Input impedance: 300k ohms, balanced. Output…
Sidebar 2: Associated Equipment
Analog Sources: Clearaudio Concept turntable, tonearm, and moving-magnet cartridge; Clearaudio Ovation turntable, Clearaudio Talisman V2 cartridge.
Digital Sources: Benchmark DAC1 HDR, Bel Canto DAC 3.5VB Mk.II D/A converters; Bel Canto CD 2 CD player; Bel Canto VB-1 power supply; Sony Vaio laptop computer.
Preamplification: Clearaudio Nano & Basic+ phono stages.
Power Amplifiers: Rogue Audio M-180, Simaudio Moon Evolution 880M (both monoblocks).
Loudspeakers: Revel Performa F30, Mårten Django.
Cables: Digital: Stereovox HDVX…
Sidebar 3: Measurements
I measured the Audio Research Reference 150 using Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com). Before performing any measurements, I installed a new set of tubes, both the 6H30 small-signal tubes and the four matched pairs of KT120 output tubes. The instructions in the manual for setting the bias current for each pair were clear: With zero input signal, each main tube was set to a voltage drop of 65mV DC, measured at its test points, with the slave tube running between 57 and…
The phenomenon of the "singing flame" has been known since the 19th century. Place electrodes either side of a flame and, if you apply a high enough audio-modulated voltage to those electrodes, the ionized particles in the flame will cause it to emit sound. (Search YouTube for "singing flame" and you'll find many examples.) This principle was developed into a practical loudspeaker in 1946 by a French inventor, Siegfried Klein, who confined an RF-modulated arc to a small quartz tube, coupled it to a horn, and called the resulting speaker the Ionophone. An intense radio-frequency electrical…
But when I raised the volume to get appropriate visceral satisfaction from the kick drum in Cornelius's "Fit Song" (ALAC rip from Sensuous: la musique de 21° siècle, CD, Warner Japan EVE016), the upper midrange was pushed too forward in the mix. I tried adjusting the level of the tweeter with the jumper, which can be set to "+1dB," "0," "–1dB," or "–2dB"; while the last setting tamed the lower treble, it rendered the top two octaves a little too mellow. I settled on "–1dB" as the best compromise, though the 5.1 still sounded too forward in the low treble.
My Lamm M1.2 Reference…
Sidebar 1: Specifications
Description: Three-way, floorstanding, reflex-loaded dynamic loudspeaker. Drive-units: horn-loaded 0.3" (8mm) Corona plasma tweeter; 4" (155mm) polypropylene-cone midrange unit; two 8.7" coated, glass-fiber/fabric cone woofers. Crossover frequencies: 200Hz, 2.5kHz. Frequency response: 32Hz–150kHz, ±3dB. Impedance: 4 ohms nominal, 3.2 ohms minimum. Sensitivity: 91dB/2.83V/m. Maximum level: 112dB/m. Operating supply voltages: 110–120 or 220–240V AC.
Dimensions: 40.9" (1019mm) H by 10.1" (128mm) W by 19.3" (490mm) D. Weight: 167.5 lbs (76.1kg) net.
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Sidebar 2: Associated Equipment
Digital Sources: Ayre Acoustics C-5xeMP & DX-5 universal players; Apple G4 Mac mini running OS10.5.8, iTunes 10, Pure Music 1.83; Shuttle PC with Lynx AES16 soundcard & dual-core AMD Athlon processor running Windows 7, Foobar 2000, Adobe Audition 3.0; dCS Debussy, Logitech Transporter, Mark Levinson No.30.6 D/A converters; Empirical Audio Off-Ramp4 USB-S/PDIF converter; Ayre Acoustics QA-9 A/D converter for vinyl rips.
Preamplifiers: Classé CP-800, Ayre Acoustics K-5xeMP.
Power Amplifiers: Classé CT-M600, Lamm M1.2 Reference, MBL Reference…
Sidebar 3: Measurements
I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Lansche 5.1's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield and spatially averaged room responses. The Lansche is specified as having a voltage sensitivity of 91dB/2.83V/m; my estimate on the tweeter axis was 90.5dB(B), which is both within experimental error of the specification and usefully higher than average.
Fig.1 shows the Lansche 5.1's electrical impedance phase angle, following the modification to the crossover. The impedance is…