The signal is fed to the positive inputs of the balanced differential stages. Feedback from the amplifier outputs is applied to the inputs, and the differential amplifiers drive a balanced Darlington-connected…
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How low can you go? "Output distortion is so low," claims McIntosh, "it defies measurement, even with the finest distortion analyzers. At mid-frequencies, 8 ohm load, the distortion meter reads the residual distortion of the test oscillator (0.0002%) with or without the MC1201 in the circuit. This means the amplifier distortion is lower than the analyzer is capable of measuring."
Setup
It's funny—sometimes I can drop a component into the system and reach almost immediate sonic harmony. Most of the time, the process is more laborious. I keep three or four preamps around here, several amps and digital front-ends, several families of cables, all of which I've used over the past few years, and the sound of each is a familiar treat. I have a good instinct for what'll work and what won't. In general, I don't feed a high-output-impedance preamplifier (Balanced Audio Technology, Conrad-Johnson) into low-impedance amplifier inputs (Linn, McIntosh). When a component is…
It's funny—sometimes I can drop a component into the system and reach almost immediate sonic harmony. Most of the time, the process is more laborious. I keep three or four preamps around here, several amps and digital front-ends, several families of cables, all of which I've used over the past few years, and the sound of each is a familiar treat. I have a good instinct for what'll work and what won't. In general, I don't feed a high-output-impedance preamplifier (Balanced Audio Technology, Conrad-Johnson) into low-impedance amplifier inputs (Linn, McIntosh). When a component is…
For instant sonic bliss, turn to track 5 of Modern Jazz Quartet (EastWest Japan AMCY1165). That's Jerome Kern's "Yesterdays," followed immediately by "Bags' Groove," another on my all-time hit parade. As Bags beat his vibes, I tapped: "It's thrilling to get this close to the music, to cozy up and feel without effort the 'vision' of the composer or performer playing out before me. That's certainly one of the privileges of being an audiophile, no? I think if more people realized how effectively audiophiles escape by 'levitating into the audiophile zone,' the High End would succeed more widely…
Sidebar 1: Specifications
Description: Solid-state monoblock power amplifier with output load impedance terminals for 8, 4, and 2 ohms. Output power: 1200W into 8, 4, or 2 ohms (30.8dBW, 27.8dBW, 24.8dBW, respectively), minimum sinewave continuous average power output rated 20Hz-20kHz. Output RMS voltage: 98V across 8 ohms, 69.3V across 4 ohms, 49V across 2 ohms. THD: 0.005% maximum from 250mW to rated power output. Intermodulation distortion: SMPTE 0.005% maximum if instantaneous peak power output does not exceed twice the output power rating. Dynamic headroom: 2.1dB. Frequency…
Sidebar 2: Associated Equipment
Analog source: Forsell Air Force One turntable, van den Hul Grasshopper Gold cartridge.
Digital source: Linn CD12, dCS 972 and Purcell D/D converters, Elgar Plus D/A processor.
Preamplifiers: Balanced Audio Technology VK-50SE, Mark Levinson No.32 Reference, Conrad-Johnson 16LS.
Power amplifiers: Krell FPB 350MC and Linn Klimax Solo 500 monoblocks, Forsell Statement.
Loudspeakers: JMlab Utopia.
Cables: Digital: XLO The Limited, RCA and AES/EBU. Interconnects: Cardas Golden Reference, TARA The One, Synergistic Research Designer's Reference…
Sidebar 3: Measurements
My usual practice is to subject amplifiers to a one-hour preconditioning period at 1/3 power. In the case of the humongous McIntosh MC1201, that meant 400W into 8 ohms from its 8 ohm output transformer tap. (One-third power is chosen because this maximally thermally stresses an amplifier with a class-B output stage.) To my surprise, the MC1201 shut down after 40 minutes or so, its heatsinks too hot to touch. This happened again during the testing. Each time, the MC1201 could be reset once it had cooled down, but this suggests that the amplifier is not recommended…
Note the rise in distortion in the mid-treble with our simulated speaker load, which suggests that the big McIntosh is uncomfortable with loads possessing moderately high phase angles. (Fig.4, taken from the 8 ohm tap, is the worst-case example.) However, this may well be of academic interest, given the amplifier's enormous power reserve and the fact that the distortion content is almost entirely third-harmonic (figs.5 and 6). Note, by the way, the enormous power levels at which these two graphs were taken; this was necessary to raise the harmonic distortion out of the amplifier's very low…
Figs.8, 9, and 10 show the monster McIntosh's THD+noise percentage plotted against output power for the 8, 4, and 2 ohm taps, respectively. (The discontinuities in the curves are due, I imagine, to the Power Guard circuit.) Again it can be seen that the MC1201 performs best when the load is approximately the same as the Autoformer tap, in which case the McIntosh easily exceeds its specified output power (footnote 1).
Fig.8 McIntosh MC1201, 8 ohm tap, distortion (%) vs continuous output power into (from bottom to top at 10W): 8 ohms, 4 ohms, and 2 ohms.
Fig.9…
Sidebar 4: Manufacturer's Comment
Editor: The following bullets are comments on the technical section of the review, starting at the beginning of the "Measurements" section.
• The output stage is listed as class-B. It is actually a class-A/B output stage.
• A comment about the 40-minute operation at 1/3 power: This is done to keep the top cover of the amplifier from exceeding 65 degrees C, which is a requirement for CE certification. The unit is designed using parts that are safely operated at 80 degrees C and higher. Allowing the unit to shut down at 65 degrees C is…
I've always wanted to review one of Madrigal's Mark Levinson products, and finally my prayers have been answered. The chosen victim? The No.32 Reference preamplifier. Note that "Reference" moniker. The No.32 is the first Mark Levinson preamplifier to carry such appellation. They're not kidding.
Power supply matters
When phono was the primary source and all circuits were single-ended, a separate power supply was the most obvious characteristic of a high-end preamplifier design. Even today, many low-gain line stages use an external power supply, despite the fact that, as Madrigal…