A Question About HUM

[GLM]

Greetings.

I asked this over on another audio forum and they kindly pointed me in this direction.

Hopefully this is the correct section for my particular query.

I am running a small home studio.

Mostly everything works fine, no issues.

However, I run a Warm Audio WA273EQ pre-amplifier on my main mix bus. The Carnhill transformers just love to let you know you have bad power.
I have a persistant 100hz hum. This only occurs with this pre-amp. The hum isnt always consistent in volume.
I have had the hum present at the different locations (bad luck with bad power/old buildings/circuits).
But I have also had the unit inspected and tested. No problems. And 2 x technicians have reported no hum in their 'clean' workbenches.

I have done the typical troubleshooting, including turning off all other power and plugging the WA273 in directly to the main socket and monitoring with headphones ... and still .. hum .. It has a ground lift, but this does not change anything.

I also have tried an IEC hum remover, which seems to have a slight improvement.

I live in Ireland in a semi-rural area. There are 2 small farms either side of me. I am pretty sure this is a general mains issue.
Longer term plan is to get a full re-wire and inspection, but not anytime soon unfortunately.

Can I simply purchase one of these and run my studio from this single socket? Is this going to give me any relief from the 100hz hum?

https://www.screwfix.ie/p/carroll-me...30v-blue/320hv

Or something like this? I know there are large/expensive PSUs you can get, with battery back up etc.
Would the above product be worth trying?

I am relatively competent with technology/gear/DIY, but power issues go beyond me.

I would really, really appreciate any clear guidance on this.

Thanks

 

[radardoug]

You dont give us any detail on what is feeding into this pre, Is it a mixer? If so, why?

 

[GLM]

You dont give us any detail on what is feeding into this pre, Is it a mixer? If so, why?

I use it both as a mic pre/DI and as an insert on my mix bus, but as noted in my post, even with the box is totally isolated, it still produces the 100hz him.

 

[dmp]

If you orient it in different orientations (rotate 90 deg in all three axis) does the hum change?

 

[radardoug]

What mix bus? If you dont tell us about your gear, how are we supposed to be able to solve your problem? We are not psychic.

 

[GLM]

If you orient it in different orientations (rotate 90 deg in all three axis) does the hum change?

Curious suggestion! I will try this out ASAP.

 

[GLM]

What mix bus? If you dont tell us about your gear, how are we supposed to be able to solve your problem? We are not psychic.

Im sorry, I dont understand the hostility? I mentioned above that the problem exists regardless of my practical use of the pre-amp. The hum is present when isolated from all other gear, and powered independently and without any local interference.

Hence, I assume this is a problem coming from my mains power. And thus, my question about using the power isolation unit as linked.

 

[radardoug]

You came on a forum to ask for help with your problem. But you dont give us enough information.
Apparently you took this peice of gear to a tech, and they said it was fine. So if it is fine, it is how you are connecting it to other gear.
But you wont tell us what other gear and how it is connected. So we cant help you. Do you think we magically know what gear you have?
I would love to be that clever!

 

[Walrus]

My understanding is that the unit outputing a hum, using headphones, when it is just plugged into the mains and NOT connected to anything else.

You say it is 100 Hz, have you actually measured this?
I would normally expect 50 Hz for radiated pickup.