"Bret Ludwig" wrote in message
oups.com...
Trevor Wilson wrote:
"Adam" wrote in message
oups.com...
Hi Everyone,
I was just wondering what people's opinions were on the famous (or
infamous?) McIntosh autoformers, i.e., whether you think they are
useful, how they change the sound you hear, et cetera. I've heard some
people say they like the sound of the MC7200, for example, which is a
direct-coupled amp without autoformers.
**Solid state amps do not require autoformers. Adding them is pretty much
like a backyard mechanic bolting a fifth wheel to a Porsche and expecting
better performance. Autoformers can ONLY damage performance of an amp.
They
cannot help in any way.
I have a Mac 2300, Mac 2200 (both have autoformers), and a Mac 2002 (no
autoformers), but have not yet done side-by-side comparisons. It
probably would be most interesting (and fair) to compare the 2200 and
2002, since they have the same rated power, but differ mainly in the
presence/absence of autoformers (2200 has 'em, 2002 doesn't...cue
music..."Almond Joy's got nuts, Mounds don't!")
**It would be fair, IF both amps used otherwise identical topology and
power
supply capacity. The only difference being the autoformers. If there are
other differences, then all bets are off.
Trevor is a bit of a nutter with a fixation against Mc's autoformers.
**A "nutter"? Ok, smartarse: YOU provide some hard facts on why YOU think
that the addition of autoformers to an already decent amplifier can possibly
improve the amp's performance. I'll wait.
This is well documented.
**Nope. What is documented is this: Bret Ludwig has a preference for
autoformer equipped amps, but cannot say why. Bret Ludwig has NEVER
performed a blind test between two, otherwise identical amps. One autoformer
equipped and one not. IOW: He has no science, no facts and no logic.
McIntosh SS amps with autoformers are reasonably well designed and
built amplifiers designed with the autoformer as integral to the unit.
**Not quite. McIntosh could have released the amps without autoformers, with
minor modifications and a substantial price reduction (and a performance
improvement).
They work well, but like most Mc products are overpriced.
Advantages to the autoformer include DC offset protection and an
ability to present an optimized load to the amplifier whether the
speaker impedance is 4, 8 or 16 ohms.
**Er, nonsense. DC offset protection can be simply effected by the addition
of around US$10.00 worth of parts. As for optimum load condictions, this is
where the wheels fall off whatever passes for technical ability. The OPTIMUM
output impedance of an amplifier is ZERO Ohms. The addition of an autoformer
will ALWAYS raise the output impedance. Always. Moreover, if an amplifier
designer wants to build an amp which can cope with 4, 8 or 16 Ohms, he can
just add more output devices. Output devices are MUCH less expensive than
iron and copper. Even better, when manufacturers do so, the amplifier has
the ability to deliver more power, as the impedance falls. Not so with the
incredibly outdated autoformer system. A system which dated from a time when
output transistors were exp[ensive and silicon was expensive. Thsoe
conditions have now reversed, so buying an autoformer equiopped McIntosh
makes about as much sense as buying a Model T Ford, in preference to a (say)
Mustang. Some people LIKE driving Model T Fords. That's their choice, of
course. There are few logical reasons to suggest that their choice is
anything but an abberation. Same deal with autoformer equipped Macs.
Disadvantages are cost and weight, and the ability of non-transformer
coupled amps to meet even better THD specs. All solid state Mc amps
except the very first models have THD specs well into the
don't-give-a-**** catregory.
**You've neglected the other disadvantages: That of output impedance and the
ability of the ap to act as a pure Voltage source.
Many good solid state amplifiers had transformers including the
legendary Altecs.
**Sure. That was when silicon was expensive and iron and copper was cheap.
Now, the situation is reversed.
--
Trevor Wilson
www.rageaudio.com.au
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