Description: Stereo tubed power amplifier with balanced inputs and 4, 8, and 16 ohm output transformer taps. Tube complement: 4 matched pairs of 6550C output tubes, 4 6H30 driver tubes. Maximum output power: 110Wpc continuous, 20Hz–20kHz at 1kHz with THD typically 0.3% at 110W, <0.03% at 1W; 120W at clipping (20.8dBW). Frequency response: 0.6Hz–90kHz, –3dB. Input sensitivity: 1.8V RMS balanced for rated output (24dB balanced gain into 8 ohms). Input impedance: 300k ohms balanced. Output polarity: non-inverting. Damping factor: approximately 12. Hum &…
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Sidebar 2: Associated Equipment
Analog Sources: VPI TNT IV turntable, Immedia RPM tonearm, Koetsu Urushi cartridge; Rega Planar 3 turntable, Syrinx PU-3 tonearm, Clearaudio Virtuoso Wood, Aurum Beta S cartridges.
Digital Sources: Lector CDP-7T, California Audio Labs Icon Mk.II Power Boss, Creek Destiny & CD53 Mk.II CD players; Pioneer DV-333 DVD player.
Preamplification: Vendetta Research SCP-2D phono stage; Audio Valve Eklipse, Audio Research Reference 3 line stages.
Power Amplifier: Audio Research VT100 Mk.II.
Integrated Amplifiers: Creek Destiny & Creek 5350SE.
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Sidebar 3: Measurements
Before performing any measurements on the Audio Research Reference 110 amplifier, I checked the bias of each pair of tubes, something made easy by the convenient probe sockets adjacent to the tubes on each of the circuit boards. All bias readings were within 1mV of the target 63mV, and the "Check" readings were all in the center of the specified range.
The specified input impedance is very high, at 300k ohms, and my estimate was in this region. (Measuring high input impedances is not very precise with our usual voltage-drop method, because of the very…
John Atkinson: Making It Live
The e-mail from Stereophile reviewer Bob Reina was straightforward: "I want to make a demo of my new jazz group. I plan to record the session in my living room by getting my old four-channel Teac 3440 out of mothballs and sticking one or two mikes on each instrument. I'd like your view on which mikes would be most appropriate for the four instruments . . . "
The e-mail from Stereophile reviewer Bob Reina was straightforward: "I want to make a demo of my new jazz group. I plan to record the session in my living room by getting my old four-channel Teac 3440 out of mothballs and sticking one or two mikes on each instrument. I'd like your view on which mikes would be most appropriate for the four instruments . . . "
After some thought, I got back to Bob with my ideas on miking and an offer to run tape for him. But what new group? Bob and I have been playing very occasional gigs in a jazz trio for the…
"Attention Screen is an attempt to do collectively in real time what a single composer does over a much longer period," explains Bob Reina. "To do that, we have to listen very carefully to what the other three guys are doing, and we have to react immediately to everything we hear to move the piece in a different direction. It's satisfying, but it's also a nerve-racking process."
In 1968, I ran into Steve Lacy on the street in Rome. I took out my pocket tape recorder and asked him to describe in 15 seconds the difference between composition and improvisation. He answered: "In 15 seconds,…
John Atkinson: Making It Different
If there is one aspect of modern rock recording techniques that tires me, it is the overuse of compressors and limiters. Not only are songs dynamically squashed to the point where they sound uniformly and fatiguingly loud throughout, even when played quietly, but the natural dynamics of the drum and bass guitar tracks, in particular, are reduced so that they are reproduced at an unrealistically uniform level.
If there is one aspect of modern rock recording techniques that tires me, it is the overuse of compressors and limiters. Not only are songs dynamically squashed to the point where they sound uniformly and fatiguingly loud throughout, even when played quietly, but the natural dynamics of the drum and bass guitar tracks, in particular, are reduced so that they are reproduced at an unrealistically uniform level.
The situation is similar in the frequency domain: modern rock recording techniques appear to demand that every instrument be…
Sidebar 1: The Music
Attention Screen Live at Merkin Hall Stereophile STPH018-2
Don Fiorino (guitar, lap steel, lotar, taro patch ukulele), Bob Reina (piano), Chris Jones (fretless electric bass guitar), Mark Flynn (drums)
Track Listing
[1] Mansour's Gift 9:52
[2] Fruit Forward 11:05
[3] Nell's Bells 10:35
[4] Bounced Again 10:56
[5] Blizzard Limbs 13:26
[6] Lap Dawg 10:52
Total Time: 66:50
All compositions by Attention Screen © 2007
CD Cover Image: Chris Jones
CD Booklet Design: Pip Tannenbaum
CD Booklet Photography…
Sidebar 2: Attention Screen: The Players
Attention Screen draws on four lifetimes' worth of jazz, classical, and rock vocabulary to create unique, spontaneous compositions that blend disparate acoustic and electronic textures.
Don Fiorino (guitar, lap steel, lotar, taro patch ukulele) Don's improvised guitar phrasings range from rock'n'roll and acoustic bottleneck blues and electric slide to Middle Eastern and Indian fusions and jazz. He plays a variety of instruments, including guitar, banjo, lap steel, ukulele, and Moroccan lotar. Don is also an accomplished painter;…
"A high-quality amplifier must be capable of passing rigid laboratory measurements, meet all listening requirements, and be simple and straightforward in design in the interest of minimizing performance degradation..."—Cdr. Charles W. Harrison Jr., Audio, January 1956 (footnote 1)
"It don't mean a thing if it ain't got that swing."—Duke Ellington
My mother was visiting. "What exactly is a preamplifier?" she asked. I explained, in some detail with helpful use of analogy (though the fact that we were in one of Santa Fe's many excellent restaurants meant that I had to…
In both its construction and its design, the No.23.5 is a thoroughly modern amplifier, engineered for excellent sonics and long-term reliability (though it is a little more complicated than Commander Harrison's definition).
Sound
The No.23.5 served as one of the workhorse amplifiers during my last six months' worth of equipment reviews. As seems to be the fate of review samples, however, the No.23.5 suffered a fault in one channel a few weeks after delivery. An increase in distortion at low levels turned out to be due to a loose washer lodging itself where it could do most damage,…