high pitch noise, possibly to do with static?

  • Thread starter Thread starter Turphy
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Turphy

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Hello. I'm having problems with high pitched noise whilst recording guitar tracks on my pc. When I record I use a Marshall g80r amp plugged into my m-audio fast track box plugged into the computer but the noise comes out louder than the music. It appears to be a problem with the amp as I've noticed that if I play straight through the m-audio box without the amp, the noise goes away. Also, the noise happens even when the amp isn't turned on but stops when unplugged, so is this something to do with the electric current interfering with the sound?
Any advice welcome but I'm hoping this problem can be solved without spending any money.
Thanks, Chris
ps. I record on audacity, dunno if that makes any difference
 
Sounds like a ground-loop issue or similar.

Need a bit more info...

Can you explain exactly how you 'plugging the amp in' (i.e. exactly what cables - balanced TRS 1/4" jack, TS jack, etc? - going from which outputs to which inputs, preamp settings on the M-audio, etc), and is there any reason why you can't just mic the amp? (which would probably get a better sound anyway) :)
 
altitude909 said:
definitely a ground loop. Just buy something like this:

http://www.zzounds.com/a--2676837/item--EBTHE2PKG
Click to expand...

...or try and work out a way to sort out the ground loop, rather than spending more money on what can best be described as 'slightly botched' solutions :)

Is the amp plugged into a different power outlet to the computer? Have you tried plugging the amp, computer and interface all into the same power outlet using a power strip?

Are you using a laptop? Have you tried running the laptop off batteries rather than plugged in (laptop power supplies are notorious for causing these problems).

Basically, more info is required...
 
Hi, sorry for slowness, I didn't think anybody had replied. The set up I'm trying to use is basically my electric guitar plugged into the 'input' of the amp via a normal guitar cable (sorry, I don't know its specifics, it's just an average lead i think); another cable connects the 'line out' to the guitar input on the back of the M-audio box and a usb connects that to my harddrive. I have my pc, its screen, the speakers and the amp all connected to one power strip plugged into the wall. With this set up both the music I'm recording and interference come out very quietly (even with the amp volume turned up to something ridiculous) with the music slightly louder. I have also tried using the 'speaker output' on the back of the amp, instead of the line out. In this instance the recording is alot louder but the interference almost drowns out the music. I have tried moving the amp further away, plugging it into a different wall socket and using a different amp (a small practice amp using the head phone socket as the line out), all to no avail. Anyway, I hopes this helps clarify things a bit, I can't really afford to take Altitude909s advice. Thanks again. Chris
 
Turphy said:
I have also tried using the 'speaker output' on the back of the amp, instead of the line out.
Click to expand...

:eek:


Seriously, you didn't actually do this did you?

Ah well, you might've got away with it...



Anyway, first of all, a line-output of an amp/head is generally not the best way to record guitar. Most of an amp's tone comes from the combination of the amp and speaker, but taking a line out bypasses all of this. This is why mic'ing an amp is the most common way of recording electric guitar, as it captures the tone of the amp as you hear it in the room - the mic itself and positioning also contribute a huge amount to the recorded tone. If you do record direct from a head, I would recommend using cab+mic impulses on the computer to emulate the effect of it running through a mic'ed up cab.

So I would recommend looking into recording the amp with mics, but for now lets go back to the basics...

Firstly, the 'guitar input' on the interface is most probably a high-impedance input designed for having guitars plugged straight into it, but you're feeding it with a line-level low-impedance signal. This is not going to be helping you... try plugging into a line input instead (or some interfaces can toggle the same input between hi-z and low-z).

Secondly, is it possible you had the input gain on the interface set really low - so low the signal dropped into the noise-floor - then when you added gain on the computer you dragged the noise up with it? Similarly, did you have the line-output level of the amp set really low (i.e. if it is actually a headphone output with a volume control - sorry but I'm not familiar with this amp) then had to use excessive amounts on gain on the interface to bring the levels up.

Basically, what does your gain structure look like? Are you familiar with good practices and such when it comes to gain structure?
 
Thanks for all the advice, looks like I've got some learning to do when it comes to making proper use of my amp. After my last post I tried just cranking everything up on it (unplugging the speaker from the head so I didn't blow my ears off) and it seemed to drown out most of the interference. This probably isn't too good for the equipment though so I think I'll invest in a mic on my next pay day. Thanks again.:)
 
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