Does power on guitar equipment affect audio input on PC and how?

Thread Starter

botchbud

Joined Jan 31, 2021
2
Hey
I've got this hunch of something that I've been trying to figure out for a long time. I know pretty much nothing about electronics btw

Alright. It's really been upsetting me. So i live in an apartment building , have a Windows 10 desktop PC with 3 audio inputs (two are internal, different cards, the 3rd is a usb audio interface). I've got some electric guitars. pedal. amp. and a recording device.

Alright, so this strange thing has been happening, and i really think it's related to power because i can't figure out what is going on. First, i was recording audio through input number 1. i was using either raw from the guitar or from guitar to amp to PC, can't remember. the cables that I use are either a 1/4 patchcord from guitar to amp and a 1/4 patchcord from headphones/output on amp to a 1/8th adaptor into the input on PC.

Either that or sometimes i use a 1/8th inch cable attached to a 1/4 adapter that goes into the amp , pedal, or the guitar.

it was working for a couple years, then the audio became distorted and then quieter and quieter, with a very slight fuzz over top indicating that the jack is still active, and then no audio. this happened on the first input, then the second. as far as i can remember i could get no device then to work on those inputs.

then i got the USB audio interface. just a simple one with speakers out and input in. so ive been using it for a month or more but i didnt use it very often. first i would just take things in off the recording device with it because i didnt wanna mess something up with my guitar, pedal, or amp. but then eventually i played my guitar through the pedal instead of the amp, thinking maybe it should be alright. i mean i NEVER had issues like this back in 2004 so i don't see why it should suddenly be a problem. However it now just stopped working from guitar to PC or from guitar to pedal to PC. I restarted pc did a full power down restarted pedal , same issue. the guitar works fine into the pedal and amp and into the recording device.

Also the recording device works fine into the computer right now. perfectly clear no issue.

do you think the cable im currently using that goes from the pedal or guitar into the PC for some reason can't handle something happening with power? it's almost like something is not equal between the devices. like why would it work with the recording device now but not from the guitar directly nor the pedal directly even though those work fine on their own? I seriously have no idea what's going on.

edit: forgot to mention there could be something wierd going on with the apartment's power because one time it fried/ messed up all my usb ports which now seem to work randomly on or off. i have no idea what that's all about but that was going on for a while and it happens every now and again

Moderator's note: Very lightly edited: Language.
 
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KeithWalker

Joined Jul 10, 2017
1,778
You probably have a grounding problem with the wiring to your AC outlets. Is your amplifier connected to a different outlet to the one your PC is connected to?
If you have a multimeter, set it to VAC and check if there is any AC voltage between the grounds on your amp an PC. If there is, connecting one to the other through your audio cables could damage the input circuits of your sound cards.
 

Thread Starter

botchbud

Joined Jan 31, 2021
2
You probably have a grounding problem with the wiring to your AC outlets. Is your amplifier connected to a different outlet to the one your PC is connected to?
If you have a multimeter, set it to VAC and check if there is any AC voltage between the grounds on your amp an PC. If there is, connecting one to the other through your audio cables could damage the input circuits of your sound cards.
Thanks for the tip. The amp and pedal are on the same outlet but the pc is on an entirely different outlet. Does it matter that they are running on the same fuse from the fuse box? this "corner" of the apartment all routes to 1 fuse in the fuse box here. WHen you say check the grounds with multimeter im assuming you're referring to the round part of the power plug on the devices?

The computer itself has 2 monitors running and they are plugged into the same outlet as the computer, would that have any negative effect?

At this moment I have a USB audio interface which is basically a small soundcard[fits in your palm] plugged into a usb port and it has a simple speaker out and mic in port. Right now the sound will not come through on the input at all from the guitar and from the pedal but it will come through perfectly when i use that exact same cable and adapter if i run it from the recording device machine.

Another related issue to grounding, I think. I get a lot of RADIO signal coming through on my guitar amplifier which can be pretty annoying. I'll hear random classical music or commercials playing through my amp. I think i heard this has something to do with grounding. Here is how my set up is:

an outlet on the right side is connected to my bass amp, and also 1 power bar, to which only the guitar pedal is plugged in right now. Some other things are plugged in but never powered on.

front side outlet is connected to power bar that has PC and monitors and speakers all plugged in and the router is also plugged in to the outlet there.

Both those outlets are running on the same fuse
 

Audioguru again

Joined Oct 21, 2019
3,171
1) Your pc has a very low level microphone input but the pedal or guitar has a very high level AUX output. Maybe the overload damaged the pc input. An old fashioned vacuum tube amplifier has an input that is not damaged by overload.
2) Audio cables are always shielded so that hum and radio stations are not picked up by ordinary unshielded wires.
 

KeithWalker

Joined Jul 10, 2017
1,778
It does not matter if the power for the two outlets are from the same breaker. That will not cause a problem unless you have faulty equipment. If the ground pins on the outlets are connected to different grounds, there could be a damaging voltage existing between them. If one or both of the outlets are not connected to ground, they can have a potential difference caused by static charge or power supply leakage big enough to cause damage on the sound card input.
 

BobTPH

Joined Jun 5, 2013
3,304
Are these mic inputs or line inputs on the PC? The fact that it works okay from the amp makes me think it is line,. In that case, the guitar output will be too low.

Bob
 

Wolframore

Joined Jan 21, 2019
2,273
There are all sorts of levels which have been confusing people since the beginning... instrument level, mic level, line level and even some of these are not the same for standard and pro audio gear. I suggest using a front end with a preamp for plugging into a computer and bypassing the PC sound cards, although they have gotten nicer, they are not generally designed for instruments.
 
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