Relay supply question

[steve_p]

Hi All,
I have a quick question about a relay supply.

I have my 124 assembled and am getting some hum on the OD channel.

I seem to remember reading here that some rectifier arrangements could possibly produce more hum than others.

I attached a schematic showing two possible ways of wiring the rectifier.
I currently have mine setup with the bridge and the CT capped off. Would it be possible that the other style shown in the schematic could produce less hum? I haven't experimented yet, but I was just looking to get a general consensus before I go off on a wild goose chase.

Thanks,
Steve

[markusw]

Did you check if the OD also hums with an external clean relay power supply? e.g. a battery? or if you replace the relay with jumpers?

Regards,

Markus

[Structo]

The OD channel is going to have more noise due to the higher gain.

Try this, when in OD stand about at least eight feet away from the amp with your back to the amp.
Now rotate your body and guitar and you should be able to find a spot where the noise is very low.
The guitar and amp react to each other from EMI.

If you are playing single coils then this will be worse.

Make sure you wire your relay power supply and specifically the grounds exactly like #124 for lowest noise.
For instance, the ground for the footswitch jack should go back around the chassis perimeter to the ground by the voltage regulator.

For what it's worth I also use a full wave bridge rectifier on my relay power supply.

[glasman]

Hi All,
I have a quick question about a relay supply.

I have my 124 assembled and am getting some hum on the OD channel.

I seem to remember reading here that some rectifier arrangements could possibly produce more hum than others.

I attached a schematic showing two possible ways of wiring the rectifier.
I currently have mine setup with the bridge and the CT capped off. Would it be possible that the other style shown in the schematic could produce less hum? I haven't experimented yet, but I was just looking to get a general consensus before I go off on a wild goose chase.

Thanks,
Steve

Both of the circuits you posted produce a 120Hz ripple and have similar current capability. the advantage of the bridge is the lower PIV requirement for the diodes. If you are sure it is the relay supply. Stiiffen the supply a bit with bigger C fats after the rectifier.

As far as hum. I have never heard it from the relay supply. Are you hearing 60hz or120 (about C on the low E string). Usually hum is assoicated with a bad ground or location of the ground (VERY important).