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What amp to pair with a McIntosh C40?

Onebean

Onebean

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In a previous thread I asked for recommendations for a McIntosh preamp. With your guidance, I have basically settled on trying a C40 (when I find one for sale). Now the question becomes, what amp to pair with it. MC7300 seems to be the mate to the C40. I'm also looking at MC7270.

What's the difference between the MC7270 and the MC7300? Which one pairs best with the C40 both visually and sonically? Are there any issues with either of these amps I should be aware of? I'm not limiting myself to these 2, it's just where I've landed after lots of reading here, and the Steve Hoffman forum. Are there other amps with relative price points I should be considering?

Specifically on the MC7270 and MC7300, is there 2 versions of widths? I have read comments about a narrow face, but I don't know what that means.

My current speakers are ADS L-910, and Bozak Grand Symphony (waiting for refurbish). I'm mainly a rock / Blues listener, with some Country, Soul, and Jazz mixed in. Will the MC7270 or MC7300 have good synergy with my speakers?
 
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I used my C40 with a MC452 until I got the C48..........you can use the C40 with anything really, but the MC7300 would be period correct I believe...
 
MC7270 is a half glass faceplate which matches the C31/C35/C37. MC7300 is full class and the match to the C40.

But wait, there's more ... enter @CruzBay to tell you about autoformer updates.
 
Imho you pair an amp with the speakers, not the pre. There should not be any reason just about any Mac amp would be fine with the C40.

Jblnut
 
When McIntosh introduced their first SS amp the Mc2505 they matched the width of their previous top flight preamp the c22 at 16 inches.

This stayed as their standard width until the MC7300 when in the middle of the production run, new management decided to expand the width of the new preamps and so Mac made the last of the MC7300 with wider glass but still the same chassis width.

The MC300 was the first amp built from the begining with the new width and would be period correct choice for a C40.
 
@c_dk thank you for the clarification on width.

@CruzBay thank you for the attached brochures. Is it possible to sonically distinguish the MC7300 from the MC7270 in a blind test? They look very similar in specs. Are the meters larger on the MC7300?

@jblnut I agree the speaker amp pairing is very important. Do you think the MC7300 and MC7270 pair well with my ADS and Bozak?
 
Well Twii is a confirmed Bozak guy and he believes any autoformer Mac amp is a mismatch for vintage Bozaks.......

The different primary winding and transitor loading of the MC7300 and later amps does change the current multiplication factor of the later amps for 4 ohm loads and lower.
 
@CruzBay thank you for the attached brochures. Is it possible to sonically distinguish the MC7300 from the MC7270 in a blind test? They look very similar in specs. Are the meters larger on the MC7300?


They sounded similar, with an edge going to the '7300. The point (at the time) was that the MC-7300 would hammer any reactive load with its current reserve, where other amplifiers (non-Mcintosh) would simply blow up.

Most other Mcintosh autoformer amps could drive the load, but you'd need to use lower Ohmage taps if the Sentry Monitor circuit started getting mad. Using a lower tap also lowers your available wattage for the load average.
The MC-7300 wouldn't need that.

In all honesty, the amps sounded similar, but we never had any speakers that presented that type of load. The XRT-22's we used have 28 drivers and are so well designed that my Marantz 8B could drive them.

Oh, and about your speakers, Mcintosh autoformer amps like most speaker just fine, and will last a good long time. I'd like to see what Chris @c_dk has to say about the capacitor's condition in the '7270, it could be close to refresh time. (edit- I've never heard a pair of Bozak's, so Twii would be the guy to ask, his depth in this business dwarf's mine.)

Mike
 
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I recall Dave O'Brien mentioning a system he had the occasion of servicing consisting of a pair of Concert Grands powered by an MX112/MC2105 combination owned by NBC anchorman Hugh Downs.

Also in the book, there was reference to a pair of MC60s also being used with a pair of CGs in a system owned by American composer Jay Livingston IIRC.

If an MC2105 (or MC60) was good enough with the CGs for men for whom money was no object, it seems unlikely an MC7270 or MC7300 would put up much of a fuss with the same speaker.
 
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Many Mac Amps would look and work fine amongst the C-40, if you wish "keeping it in the family".

Consider power and muscle as factors just in case you get a future hankering to buy some power hungry speakers.
Amps like the MC-352, MC-402, MC-501, MC-302, those all should be quite adequate. I wouldn't be too concerned with era correct. Any mac Amp would work fine, MC-2301, MC-601's MC-602, up and up, the largest major issues would be how deep are your pockets, and how strong is your back?
 
markd51 said:
The largest major issues would be how deep are your pockets, and how strong is your back?
Click to expand...

Don't forget rack size. Most of those newer amps won't fit in my rack. I'm maxed out just under 9" tall. Now, if the right deal came along, the rack issue could be overcome. :biggrin:
 
The axial west German caps used in the Mc2205 family which seem in good Teutonic fashion to fail at 20 years and a day to get the amp owner's attention, are not used in the Mc2255 or later amps so the electrolytics do not just fail but slowly just fade......so after a recap owners have made the call about improved detail and sound clarity, since the amp continues to work.

I am sure the Mc7270 will be coming due in the next few years but I have not seen one yet for anything but the bias transitor issue, same as the Mc2255.

I don't nessesarily understand Twii's issue with many of the autoformer amps, but he has stated his opinion often and so it is what it is.

It is interesting to notice Sid and his fellow engineers choice of the primary loading options they chose over the years with different amps.

In a phone conversation back when the MC2255 was very new he was adimant about his choosen primary load.....?dare I say proud, of the choice which ment that under almost all speaker loads the autoformer was a voltage multiplying device since few speakers would present a under 3 ohm load.

If you study the MC7300 schematic the primary load is now near 6 ohms, which means that it becomes a current multiplier for more speaker loads.....

In any case because of the autoformer itself it will not satisfy those that worship at the altar of the advertising spec " dampening factor" even though any good Physicist or Mathematician can show how with real speaker varibles plugged in factors above 40 or 50 don't mean much. And Sidney was both.
 
@c_dk I'm glad you mentioned the dampening factor. I was wondering if the autoformer had an effect on that specification. Although I don't "worship at the alter" of dampening factor, I look at that spec as an indication of the amps ability to control the woofer. Maybe I'm misleading myself with that specification. I always found it odd that PA amps have dampening factors higher than 1000, but don't sound significantly different than a hifi amp with a dampening factor of 100.
 
Can you imagine being a fly on the wall listening to a conversation between Coderman and Dr. Toole.....MIT vs. University of London

Like I said advertising minutia.
 
c_dk said:
Can you imagine being a fly on the wall listening to a conversation between Coderman and Dr. Toole.....MIT vs. University of London

Like I said advertising minutia.
Click to expand...
Chris - you gotta' figure that 90% of high end audio is bought on slick ad copy and ten cent sentences with $50 words exchanged by over zealous enthusiasts. I used to bring customers into engineering at Rockford and they would debate with the very engineers that designed the products they were mis-using. That amp should make more power when I run it at 1 Ohm in mono!
 
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