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Ypsilon Aelius monoblock power amplifier Measurements

Sidebar 3: Measurements

Before performing any measurements, I ran one of the Ypsilon Aelius amplifiers (serial no.31) for an hour at one-third its specified maximum power of 67W into 8 ohms, thermally the worst case for an amplifier with a class-B output stage. At the end of that period, the heatsinks were moderately hot at 44.2°C (111.5°F), while the chassis was cooler at 40°C (103.9°F).

I then measured the amplifier, using Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It"). I first performed a…

Pass Laboratories XP-30 line preamplifier

It was the strangest thing. In the fall of 2008 I was comparing Ayre Acoustics' then-new KX-R line preamplifier with no preamplifier at all—I was feeding the power amplifier directly with the output of the Logitech Transporter D/A processor. (Levels were matched for the comparisons, of course, made possible by the fact that the Transporter has a digital-domain volume control.) Being a rational being, I knew that the active circuitry of a preamplifier, as well as the extra socketry and cables, would be less transparent to the audio signal than a single piece of wire. I wanted to determine by…

Pass Laboratories XP-30 line preamplifier Page 2

The volume control, also carried on a small daughterboard, is based on a Muses NJU72320 integrated circuit. Although I am an unrecovered collector of datasheets, this chip was new to me; I asked Wayne Colburn about it. "It is part of the NJR Muses line from an in-house audiophile in Japan. They use copper lead frames and laser-trim the part. The designer of these parts came from Japan and gave samples to Nelson and myself to try and they ended up in the XP-30. I run the NJU72320 on ±15 volts so it has a large overload margin. I really like this part as it has no op-amps in it—I only used the…

Pass Laboratories XP-30 line preamplifier Specifications

Sidebar 1: Specifications

Description: Remote-controlled, three-chassis line preamplifier. Analog inputs: 6 balanced, 6 unbalanced, plus Tape Input. Analog outputs: 2 pairs (1 variable-level, Master; 1 fixed-level, Slave) balanced on XLRs; 2 pairs (Maater, Slave) unbalanced on RCAs. Gain range: –90dB to +10dB in 99 steps of 1dB. Frequency response: 2Hz–60kHz, –3dB. Signal/noise: >110dB ref. 5V. Channel separation: 100dB at 1kHz, ref. 1V. CMRR: 60dB at 1kHz. Input impedance: 42k ohms, balanced. Output impedance: 120 ohms, single-ended; 120 ohms, balanced. Power consumption: 45W.
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Pass Laboratories XP-30 line preamplifier Associated Equipment

Sidebar 2: Associated Equipment

Analog Sources: Linn Sondek LP12 turntable with Lingo power supply, Linn Ekos tonearm, Linn Arkiv B phono cartridge.
Digital Sources: Ayre Acoustics C-5xeMP universal player; Apple 2.7GHz i7 Mac mini laptop running OS10.7.5, iTunes 10, Pure Music 1.86; Shuttle PC with Lynx AES16 soundcard & dual-core AMD Athlon processor running Windows 7, Foobar 2000, Adobe Audition 3.0; dCS Debussy, Mark Levinson No.30.6, Arcam FMJ D33, Logitech Transporter D/A converters; Ayre Acoustics QA-9 USB A/D converter; Halide USB-S/PDIF converter; Mirage MMS-5A media…

Pass Laboratories XP-30 line preamplifier Measurements

Sidebar 3: Measurements

I measured the Pass Laboratories XP-30's electrical performance with Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It"). The maximum gain for both balanced input/balanced output and single-ended input/single-ended output, with the volume control set to "99," was slightly less than the specified 10dB, at 9.45dB. The volume control operated in accurate 1dB steps, meaning that the unity-gain setting was "89." The balanced input impedance was slightly but inconsequentially lower than…

Gibson To Buy Majority Stake in TEAC

It was announced Friday March 29 that guitar manufacturer Gibson was to buy a majority stake in Japanese company TEAC, which manufactures audio components sold under the TEAC, Tascam, and Esoteric brandnames. From the press release: "Gibson has entered into an agreement, signed today, with Phoenix Capital in which two investment funds operated by Phoenix Capital have agreed to sell to Gibson all the shares they own in TEAC Corporation, or 157,447,000 shares, (54.4% of the issued and outstanding shares), at a price agreed between the parties of 31 JPY per share. . ."

This is equivalent to…

Schiit BiFrost USB and Modi DACs Sweepstakes

According to the company:

Bifrost:
Bifrost is the world's most affordable fully upgradable DAC, featuring 32-bit D/A conversion, a fully discrete analog section, and a sophisticated bit-perfect clock management system, together with one of the most advanced asynchronous USB 2.0 input sections available, as well as SPDIF coaxial and optical inputs, all with 24/192 capability.

  Fully Upgradable: The Future-Proof DAC Worried about rapidly-changing USB input…

Franco Serblin

Photo of Franco Serblin courtesy of José Victor Henriques of HiFi Club Portugal
We are saddened to learn that Franco Serblin, founder of Italian loudspeaker manufacturer Sonus Faber, passed away on Easter Sunday, March 31, at 73. Larry Greenhill interviewed Franco Serblin in June 1992 for Stereophile. We will add more details as they become available.

John Marks Teaches ORTF

In a recent Stereophile.com news item, John Marks informed readers about free online music production classes now offered from the esteemed Berklee College of Music. Seems like JM himself is taking up this opportunity. In this video assigment, JM shares his explanation of the ORTF microphone placement technique for stereo recording.

Don't be deceived by this simple mic set-up! You don't need six plus microphones in order to record a full band or orchestra with realism and space. Rather, the ORTF method, devised at the Office de Radiodiffusion Télévision Française at Radio France…