Chasing 60 hz hum


I have an MC 7150 and an MC 7104 in my system, both plugged in to the same circuit on a power strip. The problem is that McIntosh went away from two prong and moved to 3 prong grounded wiring when the 7104 came along. I also moved from a C39 to an MX119 preamp, again the change from ungrounded to grounded. Having these units together on the same circuit produces a nice fat 60 Hz hum. To cure this, I used cheaters (3 to 2 adapters) on the 3 prong devices and this works.......mostly. Then, every few months the hum comes back and I go to the strip, wiggle one of the adapters a little bit and it stops....but this is a pretty goofy way to run an otherwise nice railroad....anyone got any ideas that are not radical (such as rewire the house!)
broimp

Showing 2 responses by joenies

Greetings,
I lot of people will say not to use a cheater plug, but it works. A lot of dealers use cheater plugs also due to AC hum.
Having an AC hum happens in a lot of systems.
I would suggest using the cheater plugs and maybe going with a Very Good power strip or possibly a PS Audio Ultimate Outlet, I have seen them listed here. I have used them for years in my system except on power amps. I did use them for awhile on my amps when I went with the cheater plugs with no ill effects.
After talking to my dealer I now just use the cheater plugs right into the outlet.
I had the same type of problem with AC hum, I totally disconnected the ground wires that comes from my breaker box and installed a real Isolated ground to my outlets. I ran a dedicated ground from the outlets to a water pipe in my house. I'm on a well system at my house and my well goes down 250ft. Could not ask for a better ground. Cleaned it up a lot but not totally, so I'm also using cheater plugs.
Getting rid of the hum using the cheater plugs made my amps sound Great. After talking to my audio dealer he suggested to get rid of the Hospital grade outlets that I have and go with the MIT outlets. Should get them soon. His opinion was Hospital grade outlets are not meant for audio, and I should get a nice improvement with a audio grade outlet.
If budget allows maybe a PS Audio re-generator or some other brand of power conditioner. I have read some very positive reviews of the MIT Stabilizer and the Audience ARP2-T.
I'm also purchasing a MIT Stabilizer for my front end equipment.
Hope my opinion might help you.
Joe Nies
Greetings,
In a lot of cases the 60Hz hum is not necessarily do to equipment miss wiring. It can be caused by a number of different problems.
In some cases it can be the wiring in your house. An example would be that when the Romex cable was installed and was clamped down to the J-Box the Hot, Neut. or Gnd wires could have crossed over each other at the clamp point. If this happens one of the wires could have compromised the insulation of the other wire and is causing a hum.
When I was doing a re-model of my kitchen I pinched the ground wire over the Hot wire (insulation broke on Hot lead), this in turn caused a direct short and the breaker did trip. If the wire just partially compromised the insulation this could cause a bleed through to the other wire.
A 60Hz HUM drives all us music listeners crazy.
To track down these type of problems will take a lot of time if you do the work yourself. To pay someone to do this would cost a lot of money.
I do plan to pull all my J-boxes (light fixtures & outlets) apart someday to see if this is one of the problems with the HUM.
Thanks for the advice about getting rid of the cheater plug and to just disconnect the ground wire.
I'm also purchasing a MIT conditioner for my front end equipment. I will eventually find were the HUM is coming from and fix it, it will just take time and effort.
Respectfully,
Joe Nies