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Plug Amp into Pre-Amp?

R

rickmoen

Member
I'm new to McIntosh gear, having just sold my NAD equipment. I now have an MC7200 amp and a C37 preamp is on the way. Really pleased with the MC7200! I've been reading the C37 user guide, and saw an electrical outlet on the back marked "Power Amp". The bar above these outlets says max of 1500 watts. So, I'm wondering if I can safely plug the MC7200 into the C37 and have them both go on and off together. My former NAD equipment guides warned against doing this, but it appears to me that it is OK with McIntosh. Just want confirm this with experienced users before I ruin anything. Thanks in advance for any advice offered.
 
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C37 has a built in power relay so the draw from the outlets is not running through a mechanical power switch. So long as the total demand at the bank is not greater that 1500W, I wouldn't hesitate taking advantage of the C37's convenience outlets.
 
Neither the McIntosh Compendium nor the RR site list AC power requirements for the MC7200. I did find a picture of the back of one on the Internet and the on the back panel above the power cord, power-requirement specs are listed as 120V and up to 12 Amps. That's roughly (depending on power factor) 1,440 Watts. That does not leave much margin to the 1,500-Watt rating of the C37 switched outlet but in theory it should work. I prefer to plug power amps directly into the wall outlet and that is what I would do. I would worry about current limiting (as during loud bass notes) of the AC power to the amp within the C37 (preamp) although my worries may be unfounded. Not that big a deal to throw 2 switches.

I guess you can try it both ways and if you detect no difference, use the preamp switch.
 
The [more powerful] MC7300 manual specs list the current demand from 0.6 - 12 amps (at full output) which translates to 72 watts (idle) to 1440 watts. Unless planning on running at full bore output continuously, there should be little cause for concern.

Knowing McIntosh penchant for conservatism in product specs, it wouldn't surprise me if a similar margin was built into the 1500 Watt "maximum" draw at the C37's convenience outlets either.
 
The C37 must have a serious power cord, of at least 12awg in size. If not, then I would pass on that.
 
I used the controlled power socket on my C_34 and C-29 to turn on a Mcintosh R612 power strip. You start using the sockets on the pre-amp and the contacts on the power control relay will start pitting making noise and will eventually fuse together. I have seen happen to not only me before I got the power strip that plugged directly into the wall but countless C-29, and C 30, 31,32,33,34,35,and 37 owners. Two 275's, a MC 60, witha Pioneer 750 electronic crossover with two thorens TT's and a MR-77 fused the C-29. When I went with Crown amps that required more power I got the Mcintosh power control strip. The main power came from a 20 amp wall plug, the control ac plug connected to one of the C-29's AC sockets only pulling 10 watts as I remember. It was labeled R612 Power controlled relay. It had 6 three prong 15 amp grounded AC sockets and a very short heavy heavy AC main power cord. In order for a 7200 to reach full capability at two ohms or lower it has to be plugged directly into a wall socket or one of these AC strips as It draws so much current.

Remember Pre-amp on first and off last. or Amp on last and off first, to protect your speakers.

You'll love your C-37 it was the best of the 16" wide pre-amps Mac ever made. If you get a more current preamp some day that uses a remote control with logic connections you can use a PC-4 remote controlled power box to turn off and on the 7200 and with an additional PC-4 for other additional power hungry components. A 7200 can put out close to 1500 watts across 2 ohms both channels operating simultaneously. 648 watts across 8 ohms both channels. and over 1000 watts both channels at 4 ohms. Its quite an amp. Its the first SS Mac power amp that really matched well with my woofers because of the high Damping Factor. It was designed to drive flat paneled speakers that required ridiculous amounts of power in the high frequencies where the impedance of the speakers approached 1 ohm.
 
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Yes, it's doable to use the outlet on your preamp. But, it's something that I personally discourage as there are better ways and practices.
 
A great big Thank You for the responses to my question! My C37 arrived today and I got it installed quickly. It fits on my shelf so much better than the MX-132 I was using as my pre-amp. The C37 sounds great! I did not plug the MC7200 into the preamp. The responses said that doing so should be just fine, but I'm just being overly cautious. I'll walk a few extra steps to turn the amp on and off. My upgrade bug should be satisfied for a long time now.
 
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