Integrated Amp Reviews

"We deal only in analog designs," Zurowski explained, "and the MD 208 features the three-stage front-end with special resonators that we use in our more expensive tuners. The difference is that in our standalone tuners there's an audio section handling the pure output stage: a significant audio section and a bigger one throughout. Now we take the signal right off our RF board and feed it down into the SimAudio preamp and power-amp section of the MD 208.

"The resonators are what set the front-end up. That's where it all starts, and we tune those stages for minimum distortion, plus optimum tone, resolution, selectivity, and sensitivity at three frequencies: 92.1, 100.1, and 107.3MHz...so what happens is the tuner has a very flat response across the whole frequency of FM. Many tuners will tune very well at 100MHz, but when you get down into the college stations and the art classical stations, down around 91.1 and 88.7, they've lost their range. And if a tuner isn't tuned properly for minimum distortion and maximum performance, it'll sound pretty thin.

"It's a very small increment. It's incredible, when we tune them, how a little adjustment makes such a difference with the band. But we manage to get things operating in a frequency range from 10Hz to 70.5kHz, so we give a full spectrum. This is a very sensitive, wide-open tuner. Some tuners put the emphasis on greater selectivity, but you end up with a much thinner sound; you lose the resolution, the transparency, and the definition that you get from real music—you lose the realism of the music."

Speaking on behalf of the MD 208's preamp and power stages, Simaudio's Vince Stables pointed to vacuum-pressure impregnation of its transformers as a source of the MD 208's stability. "You have a lot less eddy-current electromagnetic losses from the transformer, which results in a much quieter performance and a better regulation factor from the transformer standpoint. So you don't have filter caps and other things that will actually remove noises from the transformer and the power-supply section—there're no filter caps that will touch the signal path inside of this preamp or amplifier stage. And it employs a no-overall-feedback design, so you're handling sonic transients in real time rather than having to compensate for the backlash from the speaker. So it allows for more natural timbral accuracy...there's a single stage of feedback at the output stage of only about 6dB.

"Sim also uses 4oz copper tracings on the PC board. (Most people usually use a 2oz pure copper tracing.) It adds more gauge to the actual PC board so you can pass better dynamics through. It also has an extremely reliable volume attenuation. So it uses a fiber-optic encoder rather than a motorized potentiometer. That goes to a microprocessor that's shunted; it's basically a microprocessor with the ladder of resistors. And that shunts it off the ground plate. So at any given moment you have only a single level of resistance on the ground plate that controls volume. It makes for a very short, sweet attenuation or a volume attenuation path. And it's not very colored in terms of where you're at; all it does is add resistance to the negative point. It doesn't really depend on where your volume is set to get that sweet spot from a preamplifier, so your timbres don't shift that much as you increase or decrease volume."

Sound quality
Given the northern orientation of my listening room, my proximity to the George Washington Bridge, the iron and steel frames of the prewar buildings in my immediate neighborhood, the line-of-sight characteristics of your basic FM signal, and my apartment not allowing a proper FM antenna to be erected, I was unable to perform as thorough evaluation of the MD 208's FM tuner section as I would have liked. Looking at the MD 208's multipath meter, it was clear why my overall FM reception is horrific beyond belief, and why it's so difficult for me to pull in even the strongest local stations. Have you ever tried pointing the remote of your CD or TV at the wall opposite the unit and gotten a reflected signal that activates your source's electronic eye just as well as a direct shot? Well, that's analogous to what I experience with FM: all manner of indirect signals bounce around and vie for the main focus, so that most stations are afflicted with ghosting and all manner of grunge.

So for judging such basic attributes as stereo separation and selectivity and signal/noise ratio, I must defer to suburban guru and hardcore FM aficionado Larry Greenhill, who will offer his take on the MD 208's FM package in an upcoming issue.

As for the MD 208's integrated amplifier section, I'd never experienced a component that was so dependent on a long burn-in. People who hear the receiver in a dealer's showroom and who bring it home without a clear understanding of what is involved in its transformation from ice-cold solid-state chrysalis to fully formed musical butterfly will be disappointed. The MD 208's manual suggests that a solid 48 hours of continuous operation are necessary for the FM section to break in, but I recommend at least a month of that for the amp, and especially the preamp, to really get in sync, open up, and show their true colors. Until then, the MD 208's sound was so discombobulated that I was tempted to pack it up and ship it back.