Sorting out hum problem in system

[Audioholic]

Hi all.

I recently bought an Ayre preamplifer which I connect to a DAC and power amp. Although I can tell that the sound quality is great, there is a hum problem which it has exposed, which I believe is caused by the Dac which is actually a US model which I have plugged into a Tacima step down transformer.

Using my naim integrated amplifier I never had a problem with the hum, but with this preamp in place and the power amp switched on, even when the Bryston dac is connected to the step down transformer, and connected to a mains outlet which is switched off I can still hear the hum - it is not until I disconnect the dac completely that the problem goes away.

I just wondered, does anyone have any thoughts on how to fix this issue?

Many thanks

 

[MoJoe]

try using a ground loop isolator

 

[mmg]

It's probably not a ground loop, and I don't think the problem lies with the DAC either. The way you describe it, it sounds more like a "pin 1" problem with the Ayre pre-amp. What happens when you connect another source than the DAC to the pre-amp?

 

[Audioholic]

There is no hum when the dac is not connected and the preamp is connected in AV bypass mode to my Yamaha receiver.

 

[mmg]

There is no hum when the dac is not connected and the preamp is connected in AV bypass mode to my Yamaha receiver.

Not sure what you mean by that. Your current setup is:

Dac -> Ayre Pre-amp -> Power amp -> Speakers

right? This setup causes humming.

Your previous setup:

Dac -> Naim integrated -> Speakers

Didn't cause humming, right?

If you disconnect your DAC in your current setup, the humming is gone. This would make me think the problem is with the Ayre Pre-amp, which probably has a pin-1 problem. Check with the manufacturer and ask for a fix.

Here's some more info on how to troubleshoot systems: http://www.jensen-transformers.com/an/ts_guide.pdf