Will try to keep it brief.
Guitar/amp plugged in downstairs.
Volume on guitar up. Guitar just resting against the couch.
No hum.
Turn on computer upstairs.
Lots of electric hum and buzz from amp downstairs.
Bring computer downstairs.
Set computer up next to amp. Different socket, mind.
Turn on computer. No or negligible hum.
Tried three different sockets upstairs. Same deal. Hum from amp downstairs.
Is there some kind of ground lift or something I can use on my computer or something? I’m open to trying anything at this point. It’s a 27” iMac. Never had such issues with my Mac Mini that preceded it.
I’m thinking the actual Earth on the house, or at least the upstairs ring main needs looking at?
It’s PISSING ME OFF!!!
If I try to record guitar upstairs in the same room as the computer, if I position it just so, the hum largely disappears.
Which is what I don’t understand. The hum is largely position dependent.
I also noticed this downstairs. If I moved the guitar, the hum would get louder and quieter. Even though the computer is upstairs.
No buzz at all when computer is off and no buzz when I set the computer up downstairs (and it’s turned on) right next to the amp/guitar in close proximity.
I don’t understand this at all and it’s severely hacking me off!!!!
Comments
I’m so bored I might as well be listening to Pink Floyd
I’m so bored I might as well be listening to Pink Floyd
If the Mac is downstairs next to the amp and guitar, there isn’t a problem.
I have trouble in my house when my tumble dryer is on.
I’m so bored I might as well be listening to Pink Floyd
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
*Ground hum* is a specific type of hum (and it always is *hum*, not buzz), which is caused by a ground loop between two pieces of equipment. And you're correct, it is constant regardless of guitar orientation because it's not picked up by the pickups.
What you have sounds like the radiated electromagnetic noise from a switch-mode power supply. It is directional, so the orientation of the guitar pickups relative to the source matters.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
I have gleaned some more info.
I have tried another three sockets.
Here is the setup: Amp plugged in, turned on, guitar connected with one cable, guitar volume up. Guitar on a stand. This is upstairs.
If I attach the Mac power cable to a socket in the same room as the amp power socket, I get some short pulses of buzz through the amp. This is without the Mac being powered on. The pulses last approx 0.25s I would think. They seem random.
When powering on the Mac (every other piece of studio gear unplugged) the buzz is hideous.
Tried on the same 4 gang as the amp. Same result. Hideous buzz.
If I run an extension from downstairs and power the Mac like that, there is no buzz, and the noise that is already being produced by the amp does not change.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
It's a Victorian house and the wiring must be a complete hotchpotch.
I'll call an electrician today.
My parents had a Victorian house. One day my mum complained that she thought she got a slight electrical tingle from the washing machine, so my dad went to investigate. Sure enough, it was apparently live. He traced it back to the distribution box and found an earth wire was hanging just below the terminal block. Thinking it hadn't been secured properly and had popped out, he undid the terminal screw and poked it back in.
There was a large blue flash and everything in the house went out.
The ring main earth had been disconnected because it - and everything plugged into it, including the (luckily white-painted) washing machine casing - was live. After a huge amount of work to isolate exactly where the fault was by disconnecting the incoming and outgoing cables in each power socket in the whole downstairs of the house, we found the cause... a nail had been driven through a cable and bridged the live and earth. The "electrician" who discovered that it couldn't be powered up without blowing the fuse (pre-RCD) had "fixed" the problem by disconnecting the earth.
Done in the 1980s, not the 1880s .
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Due to the age they're probably loose anyway. AC does this over years, as it cycles up 180 back to 0 the - 180. Unlike DC which is smooth man.
Edited Disclaimer if you aren't comfortable doing this don't.