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Back in March, I wrote a reviewlet of Channel Islands Audio's VHP•1 headphone amplifier for the Stereophile eNewsletter. (What—you aren't receiving that free download yet? Well, log on to www.stereophile.com and opt in.) The VHP•1 has continued to enchant me—reason enough to examine it in greater detail, I reckoned. But the real reason I returned to the VHP•1 ($349) is that CIA's Dusty Vawter recently sent me his new VAC•1 ($159), a replacement power supply for the VHP•1's stock wall-wart supply. Could a new power supply really offer a substantial improvement in performance?
This was no small improvement, but it wasn't the biggest change the VAC•1 wrought. That would be its increase in dynamic contrast. I don't mean that the VAC•1 allowed the VHP•1 to play any louder. It may have done, but that wasn't what had me mining my CD collection for lost gems. With the VAC•1 powering the amp, there was more contrast between music and silence: where there was music, it seemed as if there was more of the stuff it was made from; where there wasn't, there was more nothing.
Is that clear? No—but it wasn't clear to me at first, either. I initially thought about it in…
Sidebar 1: Specifications
VHP•1: headphone amplifier. THD+noise: 0.00014% (no reference level specified). Frequency range: 10Hz–100kHz.
Serial number of unit reviewed: HB7309.
Price: $349.
VAC•1: power supply. Input voltage: 115/230VAC. Output voltage: 14VAC at 1.44 amperes. Accessories: IEC AC cable, AC output cable.
Serial number of unit reviewed: AB3186.
Price: $159.
Both
Dimensions: Each: 4.40" (113mm) W by 2.65" (68mm) H by 4.40" (113mm) D.
Warranty: 1 year parts & labor.
Manufacturer: Channel Islands Audio, 567 W. Channel Islands Blvd., PMB 300…
Sidebar 2: Associated Equipment
Digital Sources: Musical Fidelity X-RayV3 CD player, X-DACV3 D/A converter, Apple iPod Mini.
Headphone Amplifiers: Musical Fidelity X-CanV3, Ray Samuels Audio Emmeline SR-71.
Headphones: AKG K-501, Etymotic ER-6S, Sennheiser HD-600 (with Stefan Audio Art Equinox cables) & HD-650.
Cables: Interconnect: Stereovox HDSE. AC: stock IEC cord from JA's wire trunk, Audience powerChord.—Wes Phillips
Sidebar 3: Measurements
I measured the Channel Islands VHP•1 using the VAC•1 AC power supply. The maximum voltage gain was 16.2dB or 5.9dB, depending on whether the front-panel gain button was pushed in or not. The VHP•1 preserved absolute polarity, and its input impedance was a fairly low 6.9k ohms across the audioband. Its output impedance was a low 11 ohms at all frequencies.
The frequency response was wide and flat, and just 0.2dB down at 200kHz (fig.1). The negligible infrasonic rolloff below 20Hz seen in this graph, which was taken into 150 ohms, disappeared when the…
Warning to Purists: Despite certain qualities about the ESL-63 speakers which you will probably like, Quad equipment is not designed primarily for audiophiles, but for serious-music (call that "classical") listeners who play records more for musical enjoyment than for the sound. Quad's loudspeakers do not reproduce very deep bass and will not play at aurally traumatizing volume levels, and Quad's preamplifier is compromised through the addition of tone controls and filters, all for the purpose of making old, mediocre, and/or worn recordings sound as listenable as possible.
The Acoustical…
Incidentally, Quad's instruction booklet for the 34 preamplifier makes a very good point about listening level, asserting that for a given recording there is only one correct volume setting. I agree generally, but with qualifications. The "correct" setting is where the perceived volume of the instruments "agrees" with their apparent distance from the listener, which makes perfect sense when the recording was done with "purist" microphone technique—two, or at most three, microphones for pickup of the entire group.
But many multimiked recordings produce an ambiguous perspective, where…
Follow-Up from November 1983 (Vol.6 No.5):
Our full report on the Quad ESL-63 electrostatic loudspeaker last month was inconclusive because (1) our first two samples of it broke down and started arcing, protection circuit or not, and (2) 1 had the feeling that there must be amplifiers which would them sound better than I had them sound to date.
Since then, we obtained two more of the speakers; here's what we found:
On most program material, the '63s would play cleanly at levels up to 98dB SPL, measured at 1 meter on-axis. Above that, one speaker's protection started…
Anthony H. Cordesman wrote about the Quad ESL-63 in December 1984 (Vol.7 No.7):
Calling these Quad ESL-63s "Improved" may be a bit misleading. The only significant change in the latest Quad is a pad built into the dust cover to damp vibration in the diaphragm and control a 60Hz resonance. This change begins with serial number 13,041, and is not retrofittable.
However, there have been enough significant changes in the ESL-63 since its introduction for us to view current production as a different product, thus justifying the appellation "Improved." These changes have been: the…
Sam Tellig wrote about the Quad ESL-63 in July 1985 (Vol.8 No.3):
"You sold your Quads!!!"
My son had just returned home from college.
I wondered myself whether I had done the right thing. Probably I'd done it as an audiophile version of the three-year itch more than anything else—always trying something new. (That's why I became a reviewer: to save myself from personal bankruptcy!)
Or did I have good reason to sell the Quads? I still don't know for certain, but my time without them has convinced me that, as superb as they are, the ESL-63s are still not perfect…