MC352 into varying-load speaker?

Yes, all autoformer McIntoshes use bifilar winding (trifilar on some amps). McIntosh patented it in 1947 for their "unity-coupled" circuit, originally for tube amps of course but then they applied it to solid state in the early 60s and have ever since. I have performance data for a MC2255 and the bandwidth is nearly as wide as today's models.

I have tried Mc amps with autoformers and without, concluding that there is actually little sonic difference between them (when comparing appropriate models). The autoformer mainly acts as a stabilizer, as you said. I currently use a direct-coupled McIntosh amp myself. I like them either way. Arthur

The MC352 is a stereo amp which has two 225 watt amplifiers per channel that are fully balanced through the output Autoformer.The two amps in each channel are floated above chassis ground. The autoformer is a transformer with a coil of wire that ends in a ground point. The two amps feeding the autoformer produce one half of the sine wave each and are combined in the autoformer. The amps crossover point will float to maintain balance and if one of the amps is shorted out the other amp will complete the sine wave at its 225 watts. This design is called Quad balanced by McIntosh and will result in a signal to noise ratio of over 124 dB. This design of course uses common mode rejection.
Like a direct coupled amp the MC352 will double power if say a 2 ohm load is put on the four ohm tap. Heat and current draw will also go up. Unlike a direct coupled amp the MC352 will not halve power as the impedance is increased. With the MC you get all the power you pay for regardless of the speaker used.
The output autoformer allows the amp section to be designed for maximum linearity and efficiency which may result in say an impedance of 2.37 ohms. Since there are not a lot of 2.37 ohm speakers the autoformer is then taped to yield the 2,4, and 8 ohm point. This results in an increase in power over compromised direct coupled designs.
The autoformer has a greater bandwidth and power capability than the amp section which drives it. The MC will put out rated power to 100 KHz and swing high output current. The autoformer is an audio 'transmission' to match the amp to a variety of loads. In no way is a properly designed and built autoformer a 'buffer'.
ron-C

Appreciate all your inputs and thanks to Ron for joining in. I have a related question, that of Damping Factor for this amp, which seems fairly low at 40... what is your take on this? My present amp, 200 w into 8 and 400 into 4, boasts a DF of 400 and demonstrates that by exceptional basss control.

If I am on the wrong track please correct me... as stated above, I am interested in this amp but do not have the tech knowhow, hence the questions.

Dampening factor, slew rate, phase shift, and many other parameters are often mentioned as the key to great amplifier sound. You can find amps that excel in any one of these specs or not and the amp is still regarded as sounding good. The MC352 will put out over 400 watts which is enough for most speakers and may be to much for some. I suggest you try the amp with your speakers and to see if you are satisfied.

Ron-C

MC352 driving my Aerial 10T's sounds sweet. The 10T's are less efficient than the Usher's. The large-ish woofer requires an amp with some power and control. The MC352 sounds great with either Verve's Ella Fitzgerald re-releases, or hammering out some electric rock.

At absurd listening levels, the 10T's can suck the 352 dry. The fact that the 352 runs clean all the way into clipping, is a major compliment to its design and implementation. I do lust after the new 500W mono's though.....

I have heard "better" amps, but no where near this price range.