MC352 questions

Eharbur

New Member
After a long search, I finally found a MC352 that suited me. It sounds great, but I have a couple of questions.

The on/off switch rotates clockwise 3 or 4 positions past on position. The amp is off in these positions. Is this normal? One of the positions makes a "mechanical" sound that sounds as if the knob is moving something almost like a linkage.

The meters don't read the same when the preamp is on mono. if the left one is reading 3.5 watts, the right one is well over toward 35 watts. Is this normal? Can it be corrected?

I'm using Altec 604's, which are pretty efficient - 101 db, I believe. I'm using the 8 ohm taps. Under very enthusiastic listening conditions, the meters will bounce up pretty close to the 350 watt level. This doesn't seem right.

The amp was supposed to have been checked out by a certified Mac repair guy, but the seller has yet to produce the paperwork. Would the meter problems have been identified or corrected during a normal service? Are they even problems?

Thanks,

Ed
 
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According to the MC-352 Owner's Manual, the Power control has 3 settings (reading left to right):

OFF -> Remote -> ON

The Remote setting allows the amp to be powered up by a suitable preamp that uses a Remote signal cable. See the rear of the MC-352 for where that plugs in. Wiring diagrams are shown in the Owner's Manual for how this is connected.

Also, you will likely need to refer to the Owner's Manual to ensure that you have the proper switches on the rear of the amp set for stereo operation. There are switches that put it Mono operation and select different input connectors.

Once those items are set up properly, then re-visit the metering discrepancy. Use a signal generator - a good one is the interstation hiss from an FM tuner. Set the preamp to stereo and then use the FM tuner to see if the meters stay close to each other with the input levels on the amp turned all the way up.

Cheers,

David
 
I can't help you with technical details but it doesn't sound good.

First thing - the meters read Watts not amps.

There are only three positions on the power control as the dshoaf notes. If it goes past ON there is a problem. There should be NO sounds other than a faint click. There should be no 'pops' through your speakers either.

Also, if you are hitting 350W on the meters into speakers that sensitive, you are rocking things and I mean ear splitting \ above concert levels \ PAIN. However, there is nothing wrong with the amp hitting dynamic peaks of 350W if the music calls for it and you are being 'enthusiastic' ;)

I have never ran mine in mono mode so can't help you with what the meters do in that case.

Your right to be suspicious. GREAT AMP
 
After a long search, I finally found a MC352 that suited me. It sounds great, but I have a couple of questions.

The on/off switch rotates clockwise 3 or 4 positions past on position. The amp is off in these positions. Is this normal? One of the positions makes a "mechanical" sound that sounds as if the knob is moving something almost like a linkage.

The meters don't read the same when the preamp is on mono. if the left one is reading 3.5 watts, the right one is well over toward 35 watts. Is this normal? Can it be corrected?

I'm using Altec 604's, which are pretty efficient - 101 db, I believe. I'm using the 8 ohm taps. Under very enthusiastic listening conditions, the meters will bounce up pretty close to the 350 watt level. This doesn't seem right.

The amp was supposed to have been checked out by a certified Mac repair guy, but the seller has yet to produce the paperwork. Would the meter problems have been identified or corrected during a normal service? Are they even problems?

Thanks,

Ed

The power switch has three positions, OFF/REMOTE/ON, if it is moving past these positions there is a problem with the switch.
Are you sure its not just that the key way indicator on the actual knob is just not lined up to the text on the faceplate?
Or does the switch actually moving more than three positions?

Have you checked the amplifier is not switched to mono mode....
Are you using the XLR inputs or the RCA inputs, do you have the input switch in the appropriate position?
Have you tried swapping the inputs (left to right and right to left) to the MC352 to establish if the pre-amp is putting out the same level from both channels?
If you swap the inputs and the problem moves to the other channel, then the preamp is at fault....
If the problem stays the same then its the MC352.
Does it sound like the level between Left and Right is balanced regardless of what the meters say?

101db efficient speakers and you are peaking at 350watts?? Are you kidding, thats close to breaking windows or blowing your speakers up....:yikes:

How loud is it? have you got a decibel meter?

I have seen this comment many times, and it seems that it is always inevitable that the amp has not been properly checked...
Amp has been checked by certified McIntosh service tech yeah right!!!

Yes, if there was an issue with the amplifier it should have been identified and/or repaired during a service/repair....
 
After a long search, I finally found a MC352 that suited me. It sounds great, but I have a couple of questions.

The on/off switch rotates clockwise 3 or 4 positions past on position. The amp is off in these positions. Is this normal? One of the positions makes a "mechanical" sound that sounds as if the knob is moving something almost like a linkage.

The meters don't read the same when the preamp is on mono. if the left one is reading 3.5 watts, the right one is well over toward 35 watts. Is this normal? Can it be corrected?



Thanks,

Ed

The power switch should only have 3 positions OFF/Remote/ON. It sounds like you have a bad power switch that needs to be checked out.

Regarding the meters being different I think this may be a common problem with the MC352. I recently moved to a new residence and boxed the amp in its original box for the move and carefully had it moved to the new residence. After setting it back up the meter for the left channel is now showing about 10dB higher than the right channel. I have determined by troubleshooting the problem is the meter.

I think your best bet would be to get your amp checked out by a real qualified McIntosh service technician.
 
Definitely sounds like some things are not right with that amp. Perhaps it took an impact during shipment at some point.
 
Good points, all.

The off/remote/on knob works fine but definitely has 5 detents past the off/remote/on positions. I guess someone replaced the original 3 position with an 8 position rotary switch.

The switches on the back are both in the correct position. I tried switching the XLR cables right to left with no result. Then I tried the interstation hiss and the meters read virtually the same, which makes no sense to me at all.

I'll admit, the music was pretty loud. It was a live recording of a bass "oriented" passage where the drummer and the percussionist where trying to shake the building - a mid-size civic center, and as I recall (I was there when it was originally recorded) they did a fine job of it. Not a crazy amount of mids and highs, but a whole lot of sound. Good fun!
I'll also admit that a couple of diaphragms gave their all for rock and roll….

I guess the amp goes back to the seller (a dealer) or off to reputable Mac dealer, after paying for which, it wasn't such a great deal after all. Guess there is a lesson there. Still, the amp sounds great.

Thanks,

Ed
 
I'm not convinced there is anything wrong with the amplifier other than the unusual power switch. Who knows the story with that ...

Test tones and pink noise are great tools to set levels and check for proper functionality.
 
It sure sounds great; noticeably better than the MC7270 that I bought last year from a REAL reputable dealer, but then again, having never heard another MC352, I'm not sure what it should be capable of, or, for that matter, if I could tell the difference.

Is it possible to adjust the meters?
 
Most McIntosh amplifiers have two adjustments for the meters:

Adjust for meters at rest (no signal).
Adjust for meters at full power.

Those adjustments are easily made by a competent McIntosh technician.
 
Yeah,
Maybe work with the dealer as you said meters are equal on noise signal.
Not sure about the switch but you could replace that with original, dealer might pick up the tab.
352 is a great amp I'd like to to get one to replace my 2205.
Good luck.
 
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