Cary Audio Design CAD-805 monoblock power amplifier Page 4
Even off the 4-ohm taps, the bass lacked impact and a convincing foundation. Taj Mahal's "John Henry's Fiddle" (string bass) on "Texas Woman Blues" (from Recycling the Blues & Other Related Stuff, Columbia 31605), while sounding full enough through the upper bass, sounded murky, lacking definition in the midbass. That impedance magnitude below 70Hz is a killer for a single-ended amp. The Legacy's current-drive demands proved too much for the 805.
I did experiment with the feedback control, which turned out to be rather instructive. Increasing feedback improved the resolution of transient detail, which I felt was being obscured, as if a thick glaze was overlaying the soundstage. The sense of speed and directness also improved, at the cost of some lushness. About 5dB proved right to my ears.
Both the magnitude of harmonic distortion and the output impedance are reduced with increased feedback. If you desire a softer, less distinct presentation, then no feedback is what the doctor ordered. On the other hand, increased purity and directness with a small level of feedback appeals to me as a more realistic balance between music's hard and soft textural qualities.
Driving the Legacy with the much more expensive and higher-powered Jadis JA 200 monoblocks drove home the 805's limitations. The Legacy's upper octaves opened up significantly, while treble transients sounded faster. Bass control improved dramatically; bass lines were tighter and much easier to resolve. Soundstage transparency also improved, all the hall's recesses lighting up. What was missing, however, was that beguiling lushness, that romantic touch that allowed the 805 to speak more effectively to the heart.
It's a given that any small power amp will be routinely driven into clipping. The 805's ability to clip gracefully and recover quickly, without harshness, was very evident with this speaker. There was none of the pronounced ringing and oscillation that often plague push-pull designs. The 805's ability to move from soft to loud was quite impressive. Only when attempting to scale the dynamic range from loud to very loud did it run out of steam, especially with speakers whose sensitivities were at the lower range of acceptability. After all, there's a limit to what 25W can do. Compression was subtle, not gross and harsh like a rubber band stretched beyond its elastic limit.
Solo Electronics H500: This high-sensitivity (96dB/W/m), $2480/pair loudspeaker features a 2" titanium-diaphragm compression driver loaded by a wooden exponential horn. The horn driver is crossed over at 1kHz to a pair of 8" poly-coned woofers. A titanium metal-dome tweeter is used to fill in the extreme treble above 12kHz. This visually attractive three-way caught my attention at the 1993 Winter CES, when it sounded very listenable indeed. The nominal impedance is 6 ohms, which, together with its sensitivity spec, makes the Solo H500 quite attractive for single-ended applications. Matching Sound Anchors stands, which elevate the enclosure to the proper listening height, are available.
Critical listening in the reference room showed the H500 to be grossly colored in the midrange. (I experienced a similar frustration with the PAS Studio Monitor that I reviewed a year ago (footnote 5).) Considering that the speaker was designed by audiophiles, I'd hoped for more. My measurements noted problems in the integration of the horn and woofers. The horn's cutoff frequency simply isn't low enough, resulting in a discontinuity at the crossover point. The upper mids feature far too many resonances to make this loudspeaker a serious tool for evaluating associated equipment. Dynamic headroom was great, but the voicing was too far off-base for me to pursue the Solo experience.
Audio Artistry Mozart: This $2495/pair two-way design features three Vifa drivers: two woofers flanking an aluminum-dome tweeter, à la Joe d'Appolito. A product of computer-aided design, the Mozart lived up to its namesake in the sense of evincing a classic tonal balance. Although bass extension is flat to only about 50Hz in-room, the lower mids and upper bass are full, and the midbass is well-defined, lending a convincing foundation to jazz and classical music. The Mozart's ability to preserve the rhythmic drive and pacing of live music is outstanding. The treble is equalized to be flat on-axis—a refreshing change from the rising high end of which so many designers are enamored. I took an instant liking to this speaker.
The Mozart also measures very well, which implies that its drivers integrate smoothly. Designer Marshall Kay took a calculated risk by crossing the tweeter over at 1.8kHz—rather low by metal-dome standards. His tests have shown that this particular tweeter can handle a lot of power around the crossover point with little distortion. As a result, the Mozart is blessed with excellent dispersion through the critical midrange. Its ability to suspend a wide, spacious soundstage in the front third of my Reference Room is quite remarkable. The sensitivity is about 91dB/W/m and the nominal impedance is around 6 ohms, without any impedance dips below 4 ohms. I'm told that CAD's single-ended amps were used as part of the design process to refine the speaker's voicing. This I could readily believe after my first listen to the Mozart with the 805.
Footnote 5: Vol.16 No.1, January 1993, p.183.—John Atkinson