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McIntosh C2700 (and C53) passthrough function

M

Mvp119

New Member
I am having an issue with my McIntosh C2700 preamplifier. I have recently integrated the C2700 into my home theater system using its passthrough function. However, I have encountered a discrepancy between the expected behavior and my actual experience.

According to the user manual and online forums, the passthrough function should operate regardless of the preamplifier's power state. However, in my setup, the C2700 must be powered on prior to the receiver for the passthrough to function correctly.

I have observed the following:
  • C2700 Off: When the C2700 is powered off, the receiver's 12V trigger activates it. Although the C2700 turns on and enters passthrough mode, audio signals do not pass through. (sometimes the meters move, which shows that the input signal is entering the C2700, but there is no output).
  • C2700 On: When the C2700 is powered on, the receiver's 12V trigger activates it. The C2700 switches to passthrough mode, and audio signals pass through as expected.
I have attempted to troubleshoot this issue by:
  • Replacing the C2700 with my C53 preamplifier. Functions the same way.
  • Using the C53's output trigger to activate the C2700's passthrough. (just to make sure there isn't an issue with the surround receiver 12v trigger).
  • Testing different inputs on the preamp. I am currently using the "Balanced 3" input for passthrough.
  • Switching the amplifier from "Main" to "Output 1".
I would appreciate any guidance or troubleshooting tips you can provide to resolve this issue.
 
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Do you get any sound if you run the AVR outputs to a non-passthrough input on the preamp, then manually select that input? Just thinking of verifying that the AVR output is working as expected.

FWIW, I use HT passthrough on my MA8950 and it works as expected (powers up with 12v trigger from AVR, selects passthrough, and produces sound). There is one time that I experienced a similar behavior to what you are describing, but it turned out to be user error. I had accidentally turned off 'output 1' somehow.

I have noticed that certain HT material (some TV channels for example) have very little audio in the main L/R channels which can make me wonder if the passthrough is working properly. I have found that the music channels are good ones to use to verify things, because they have two channel audio.
 
If you can sub the C53 for the C2700 and the PassThru works as expected on the C53, the C2700 requires service.
 
I have a C2300 operating with an MX120 and the passthru operates only when the preamp is on. In other words, when I use the C2300 for stereo listening it’s on and the MX120 is off however when I use my home theater they are both on. That may be the case with the C2700 as well regardless of what the manual says. I’d call McIntosh directly and I’m sure they’d help answer the question. Hope this helps.
 
frodaddi said:
Do you get any sound if you run the AVR outputs to a non-passthrough input on the preamp, then manually select that input? Just thinking of verifying that the AVR output is working as expected.
Click to expand...
Yes, the sound passes through other inputs. And passthrough works as well if the C2700 was powered up before the surround receiver.
 
damacman said:
If you can sub the C53 for the C2700 and the PassThru works as expected on the C53, the C2700 requires service.
Click to expand...
I tried swapping the C53 in and it works the same way as the C2700. Both need to be turned on before entering passthrough mode.

I figured, either both of these units are bad, or they need a firmware update, or something else is wrong with my setup. But I can't think of anything in my setup that was cause the issue.
 
The only other thing I can think of is the trigger cable? The Mc wants a 'stereo' type trigger cable whereas my AVR uses a 'mono' type cable. So in my case I used a mono cable with a mono / stereo adapter on the Mc trigger input. I suppose it's possible if you use a regular mono cable into the Mc something unexpected might happen?

I mean it doesn't seem obvious why that would result in what you are seeing but I guess it is possible? It sure seems unlikely that the 2700 and the 53 are both 'broken' in the same way...
 
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