Hey guys, I have isolated a slight hum from my new MC462 when no music is playing. I've connected it to my preamp using balanced cables. Is this normal? If it's a problem with the amp itself, I obviously would want to replace it ASAP. Sounds great when playing music. Any advice would be appreciated, thanks.
Hum is not audible through speakers, and doesn’t fluctuate through changes in volume? Does it go away when unplugging preamp? Shouldn’t be ground loop if balanced cables but maybe an impedance imbalance… Could be something loosened during shipping.
I have a 452. I would not consider that hum normal. Can you try an outlet on a different breaker? I'm assuming you've got it plugged directly into the wall?
I've tried different outlets, same issue. If I disconnect the cables from preamp and turn on, I get an unpleasant noise. I'm starting to think that I need a replacement.
What about the location of the unit, is it close to other electrical equipment inc audio. Transformers can induce noise, move it to another place. Also, I would disconnect the cables in the amp side not on the preamp as the cable could be the culprit.
Based on the specs you shouldn’t have any audible hum coming through your speakers. At most, only a slight hiss with high sensitivity speakers. Disconnect the cables between the preamp and amp (make sure the amp is off when doing this). If the hum can still be heard through the speakers when it’s powered back up then it’s time to send it in for an evaluation.
To clarify, the hum is not coming from the speakers, it's coming from the amp itself. It is isolated away from other pieces. I'll have to try different cables.
If it wasn’t doing this prior then it’s one of three possible issues: the transformer has come loose from the chassis, it needs repaired/replaced, or you are now getting some DC offset on your incoming power. You can try a DC blocker. An effective and affordable DC blocker is the AVA Humdinger: HumDinger DC Line Blocker All of the incoming power for my audio components is routed through a couple of Humdingers to minimize stress on the transformers. Probably wouldn’t hurt to have one in your system regardless, considering how common an issue DC offset is these days. They’re the one type of power “conditioner” that actually function as advertised. Good luck and please keep us updated on the resolution. If you’re like me then you despise noisy gear. It irks me that these days one can get a completely silent AVR from Best Buy for $200, yet many expensive audiophile amps are noise factories (Mac is one of the exceptions though and normally very quiet).
If you're using balanced cables, make sure the switch is set to balanced at the rear of the amp. I have MC501 Monos and when using balanced cables, I inadvertently had the switch set to unbalanced resulting in a audible hum.
Thanks all. I disconnected everything except the power cord, tried different outlets, and I still get the hum. Talked to McIntosh Tech, and he told me that there really shouldn't be an audible hum, but some units may be slightly noisier than others. Because this is so new, they told me that they could replace it for me. I think I'm going to go that route for peace of mind. Thanks again!
