Roy Harris -- I have been looking for a tube preamp since I noticed recently that my main and back-up preamps were experiencing electrical difficulty. Consequently, I auditioned a number of preamps in my own stereo system, at CES 2007 and at the homes of members of a local audio club. I owned a Mac C22 preamp many years ago and was curious about the performance of its latest incarnation, the C220. As a result of my brief exposure to the C220, I can assert, with confidence, that this preamp is not your father’s Mac preamp, unless of course, he owns one.
Tube Compliment: 2-12ax7, line, and 2-12ax7, phono. Power Supply: Laminated steel R-core. Resistors: 1 percent metal film. Capacitors: Wima polyester in signal path for use in tone control circuit. Design Goal: Neutrality, i.e., input=output. Volume Control: Digital, controlled manually or via hand held remote. Line stage has 15 db of gain. The display will show a number between 0 and 100. Readings from 0 to 69 attenuate gain. 70 db is unity gain. Readings from 71 to 100 increase gain. A reading of 50 is equivalent to a position of 12:00 on an analog volume control. Tone Control: treble and bass may be attenuated or raised, maximum 12 db. at 10000 Hz, each hour signifies about 2.4 db-peak or dip. At 7:00, 10000 Hz is down about 12 db, while at 5:00, 10000 Hz is up about 12 db. At 20 Hz, each hour represents about 2.4 db of gain. At 7:00, bass is down about 12 db, while at 5:00, bass is up about 12 db. When looking at the treble adjustment curve, one observes a frequency of about 1400 Hz as up or down 2 db. When examining the bass adjustment curve the 2 db point is around 300 Hz. Both bass and treble curves are non-linear.
This preamp was different than other preamps I have auditioned in my stereo system, in that it seemed to exhibit less “color” or sonic signature. It was difficult to detect flaws or deviations from neutrality. During the review, I varied other components in the chain, including amplifier, cables, CD players and accessories. The effect of each change was more readily apparent and differences in the sound of components were discerned in a very short period of time. This observation embodies the essence of the preamp. Any other statements about frequency response, soundstage, dynamics and other “audiophile” terms are unnecessary.
Here is some evidence to support my position: Holly Cole’s rendition of “I Can See Clearly Now”, from DON’T SMOKE IN BED, Alert Z2 81020, exposes the effect of close-miking, namely the presence of sibilance. Depending upon the combination of CD player, interconnect and line cord selected, sibilance was either exaggerated or natural sounding. Pete Christleib’s tenor sax solo on “Deacon Blues”, from Steely Dan, AJA, MCAD 27314, either over-emphasized the upper midrange/lower treble, sounding more like an alto, or sounded more timbrally correct, depending upon associated component choices.
TWO OF A KIND, MHS 5162443, is a collaboration between Bob James and Earl Klugh. On track 3, “Sandstorm”, Klugh plays a nylon string acoustic guitar. As I alternated several components in the stereo system, I observed a change in the spectral balance. In some cases there was not proper emphasis upon the lower midrange. In such cases, the timbre was inaccurate. The strings sounded thin and steel-like, while at other times, there was a better proportion of the body of the instrument to the strings. “So What”, from KIND OF BLUE CK 64935, exhibits tape hiss. Depending upon other components in the system, the tape hiss (noise) relative to signal either increased or decreased. Other examples can be provided to reinforce the central theme of the review, namely that this preamp reveals the sonic signature of other components to a greater extent than I have previously experienced. However, additional data is not needed. One must hear to believe.
While it seemed that this preamp exhibited less distortion than many other components I have heard, no component is perfect. A viable company selling a product at a price point [USD$3,300.00], at a specific profit margin, has implicit cost constraints for the parts selected during manufacture. The imperfection that is built into the creation of the product can be observed if sufficient time is taken during the audition process. I believe there are two very minor deficits from neutrality, namely minimal frequency response errors, typical of modern tube designs. However, they were barely noticed and, in any case, unobjectionable, given the context of listening to music in the home, where one does not expect perfection. The regions of the frequency range where I noticed the slight deviations from flat frequency response include a boost in the upper midrange/lower treble and an attenuation in the upper/bass/lower midrange. In spite of the two aforementioned deficits, this preamp is a very useful component for a reviewer, as it offers an opportunity to observe quickly and efficiently, the impact of changes in components upon the sound of a stereo system.
Further information: McIntosh Laboratory