[95bcwh]

All,
  When I plug my amp and my preamp into the same circuit, my amp hums.. I thought it's the ground loop issue so I use a cheater plug on my preamp but my amp still hums. I also have a Running Springs Haley with 3 isolated duplex, and when I plug and amp and preamp onto each isolated receptacle, my amp still hums.

The only way to correct it is to have my amp and preamp on two different circuits.

I wonder what can cause this?

Thanks for your comment.

Barry

[Stu Pitt]

Maybe they're too close together?  Can you move the amp further away and see what happens?  If you move it as far as possible and it diminishes somewhat, this may be the reason why.  You could then get a longer interconnect.

Are your power cords close to your interconnects?  If they are, seperate them or cross them at a 90 degree angle.

Then again, if its the amp itself and the hum isn't coming from the speakers these may not be the issue.

[95bcwh]

Oh no..sorry..I should be more explicit..the hum is in the amp..I can't hear it on the speaker..

[ckoffend]

What kind of amp is it?  There are some amplifiers I know of that have transformers that over time can develop a low level, but audible buzz or hum.  Typically, there is little that can be done about this short of replacing the transformer/power supply.  From what I understand, there normally is not an audible inpact to the performance of the amp.  Frequently, it is only the owner of the equipment who ever notices it anyway, sort of like when you paint your own walls you forever notice every little blemish that all your guests would never see.

How loud is the hum?  What kind/model of amp?  Is it tubed?

[95bcwh]

Moscode 401HR... The hum is very low level...ok...sorry..maybe I should call it a "buzz", a transformer "buzz". It's audible when no music is playing.

It's probably not transformer defect.. because as I said when I plug the preamp into a different circuit, the hum's gone!

[NewBuyer]

...It's probably not transformer defect.. because as I said when I plug the preamp into a different circuit, the hum's gone!

Does this same-circuit hum happen when the interconnects are removed?

[ctviggen]

That's my question, too.

[anthony a.]

yup. could be intereference from interconnects or even one component may not be completely shielded and causes the tranny to hum.  i had that happen once to me when a certain component was sitting too close to another.  turns out that neither component had a stainless steel "shielded" case, so hum was evident.  also had seakers cables hum when placed too close to a component/power cable.  could be many things, i would try removing all cables first or moving them around to see if the hum increases or decreases.

[95bcwh]

I found the answer!! It's not the interconnect. It's the power supply of my preamp!

I replace the power supply and the hum is gone! It must be that some DC leaked out of the power supply of the preamp and got into the circuit which caused the transformer buzz!

Strange..but that's the way it is...

[TomS]

What pre?

[95bcwh]

Sorry can't disclose the name because doing so will risk me being banned from this site!!

Suffice to say that the power supply of my preamp is a modified version, and it's actually the modder who suggested to me to take out that power supply and replace it with the stock one to see if it makes any difference.

The modder has told me to send back the power supply for him to fix because it has life time warranty.. 

What pre?

[lonewolfny42]

Sorry can't disclose the name because doing so will risk me being banned from this site!!

What pre?

Too late....its in your signature.....

[TomS]

duh, for some reason I was thinking that was the amp    Never mind.