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Yesterday, before Barbirolli's Mahler, I played my favorite Jethro Tull album, Stand Up (Island ILPS 9103), partly to enjoy the music, partly to compare that newly acquired (first pressing!) UK copy with my tried-and-true US copy (Reprise 6360). The GrooveMaster II was notable for presenting Ian Anderson's voice as tonally uncolored and spatially present as does my more expensive EMT 997 tonearm, and for being no less effective at allowing the recording's more percussive sounds—Clive Bunker's bongos and the note attacks of Anderson's balalaika in "Fat Man"—to stand proud of the mix. And,…
"How natural the sound," wrote Jonathan Scull in March 1994, in his Follow-Up on the original Jadis JA 200 monoblock amplifier, which then cost $18,990/pair. "How easy it was to follow the musical line and fall into the music. How deep, controlled, tight, and satisfying the bass. How magnifique the midrange—the traditional strength of the Jadis presentation. How full and satisfying the lower midrange. How open, airy, how right the highs—not at all hard, but very extended and natural. How involving their presentation. How full, how harmonically correct, how wonderfully compelling. How magical…
Although Monsieur Scull went to great lengths to position the JA 200s' amplifier and power-supply chassis some distance apart and at right angles to each other, M. Calmettes had no such concerns. We simply placed the pairs of enclosures side by side, a few feet apart: Each channel's power supply sat on the floor, supported by Grand Prix Apex feet, with its corresponding mono amplifier resting 4" above it, on a Grand Prix Monaco stand. A 15-amp Nordost Odin 2 power cord fed each power supply, and Odin 2 speaker cables were attached to one of the two sets of binding posts on amp's rear.
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Sidebar 1: Specifications
Description: Tubed, push-pull monoblock power amplifier with separate power supply. Inputs: can be ordered unbalanced (RCA) or balanced (XLR). Tube complement: ten 6CA7, KT88, KT120, or KT150 (choice of matched tubes on request, requires internal modification at factory); one 12AU7 (ECC82); one 12AX7 (ECC83) in driver stage. Outputs: 2 pairs binding posts in parallel to permit biwiring. Output power: 170W at 1kHz, 3% THD. Output impedance: 4–8 ohms, set at factory, adjustable by internal coupling from 1 to 16 ohms. Input impedance: >100k ohms. Bandwidth: 20Hz…
Sidebar 2: Associated Equipment
Digital Sources: dCS Paganini SACD/CD transport & Network Bridge & Scarlatti clock & Vivaldi DAC, Apple iPad Pro.
Power Amplifiers: Pass Laboratories XA200.8 monoblocks.
Loudspeakers: Wilson Audio Specialties Alexia.
Cables: Digital: AudioQuest Diamond (FireWire, Ethernet), Nordost Odin 1 & Odin 2, Wireworld Platinum Starlight Cat8 (Ethernet). Interconnect, Speaker, AC: Nordost Odin 2.
Accessories: Grand Prix Monaco rack & amp stands, 1.5" Formula platforms, Apex feet; Nordost QB8, QX4, QK1, QV2 power accessories; Isotek…
Sidebar 3: Measurements
I measured the Jadis JA200 Mk.II with my Audio Precision SYS2722 system (see the January 2008 As We See It"). One point to note is that with 10 KT150 tubes packed closely together on the amplifier chassis, the JA200 Mk.II gets very hot. After a couple of hours, the temperature of the top panel by the output transformer was 169°F (76.2°C)!
The voltage gain into 8 ohms was 30.5dB, and the Jadis preserved absolute polarity (ie, was non-inverting). The input impedance was very high, at >500k ohms at low and middle frequencies, and still 300k ohms at the top…
The XA25 stereo amplifier is the latest addition to Pass Laboratories' XA series of amplifiers and, at $4900, the lowest priced. It weighs only 45 lbs, has single-ended inputs only, and outputs 25Wpc into 8 ohms, 50Wpc into 4 ohms, or 100Wpc (!) into 2 ohms. According the XA25's well-written owner's manual, it will deliver 50W peaks into 2, 4, or 8 ohms—in class-A.
As Nelson Pass, founder of Pass Labs and the XA25's designer, writes in that manual: "The signal path from input to output has been simplified to fewer components. Degeneration, 'the other form of feedback' has been eliminated…
The ancient poetry of El Din's singing is driven and supported by playing of the oud, and the first thing I noticed was how full and authentically wooden his instrument sounded. The second thing I noticed was how the XA25 revealed the vibrations in the spaces between the oud's string courses, sound holes, and soundboard. I could sense the XA25 reproducing a boiling, stream-like continuum of acoustic energy.
This is what high-quality audio is supposed to do: make the energy coming out of the speakers resemble the energy that went into the microphones, so that wooden instruments sound…
Sidebar 1: Specifications
Description: Stereo power amplifier using JFETs and MOSFETs. Inputs: 1 pair single-ended (RCA). Outputs: stereo pair of Furutech binding posts. Power output: 25Wpc into 8 ohms (14dBW), 50Wpc into 4 ohms (14dBW). Peak current: 10A (200W peak into 2 ohms). Bandwidth: DC to –2dB at 100kHz. Input impedance: 47k ohms. Voltage gain: 20dB. Distortion: 0.1% at 25W, 8 ohms, 1kHz. Noise: <50µV output, unweighted, 20Hz–20kHz. Damping factor: 500. Slew rate: 100V/µs. Idle power draw: 2.0 amps at 120VAC (240W).
Dimensions: 17" (430mm) W by 6" (150mm) H by 17.3" (…
Sidebar 2: Associated Equipment
Analog Sources: AMG Giro G9, MoFi Electronics Ultradeck turntables/tonearms; AMG Teatro, EMT TSD 75, Hana EL, Koetsu Rosewood Standard, MoFi Electronics MasterTracker cartridges.
Digital Sources: Mytek HiFi Manhattan II, Schiit Audio Yggdrasil DACs; Integra DPS-7.2 DVD player (used as CD transport).
Preamplification: Auditorium 23, Bob's Devices CineMag 1131, Dynavector SUP-200, Lounge Audio Copla JFET-MC step-devices; Lounge Audio LCR Mk.III RIAA, Parasound Halo JC 3+, Tavish Design Adagio phono preamplifiers; Linear Tube Audio microZOTL2.0, Pass…