Reamp problems - noise

[matt youwin]

So recently I've reamped some guitar parts for some projects I'm working on. The main problem I'm having is excessive noise/hum and some clicks/pops coming through when recording the reamped signal.

The noise/hum seems like a ground loop hum type of problem. It seems to change in intensity/frequency in relation to what the computer is doing - ie opening a session/processing something/pc under load = lots of noise, while there's less noise while idling. The most extreme example came when I opened one of the preferences menus in pro tools - mousing over the list of options ceased the noise almost completely, but the noise returns whenever you click anywhere else in the window. I've tried the ground 'lift' on my reamp box to no avail.

The clicks/pops I think may be unrelated (I haven't had a chance to test whether they were present when recording anything else. I have noticed some in the past but nowhere near as many as I noticed while reamping.) They seem like a 'glitch' in the signal, as if it was having trouble syncing or something.

Has anyone else had any similar problems? Any suggestions? I've tried a search but haven't had much luck.

My setup:

PC running Windows XP SP3, 4GB RAM, 3GHz dual core intel processor
M-Audio 1814 connected by Firewire (bus powered, though I do have an AC adapter I can use)
Presonus Digimax FS (using these pres to record, and also syncing to this via lightpipe)
Cuniberti reamp box (fed by output 3 on the M-Audio using a TRS/XLR3 adapter)
Peavey 5150 MkI + MkII

Any help would be appreciated.

 

[TheWinterSnow]

test the ground lift, should fix the ground coming from the computer, even though you have used it and it doesn't work, that's a huge sign that the switch isn't working or the polarity of the 1/4 jack on the interface is reversed. all the little digital noises that travel through the grounds will travel through audio devices like headphones or anything that has an output. the pops and clicks while you are playing audio is a sign that you have your buffer size set too low, or that you have bad asio drivers.

i did recently notice that some USB devices ground in opposite polarities and your basically adding negative to negative. i noticed this with my computer when some USB cables when being plugged in cause a huge spark. so you could have some bad ground loop withing your computer, try removing unneeded USB/Firewire cables, the raw basics for using your computer and recording. and make sure your reamp box isn't touching anything that the computer case is grounded to. if you are using a battery backup, unplug its USB connection to your computer, they are reversed.

also make sure that you are using TRS to XLR cables and not TS cables in between the interface and the reamp box, becasue that would defeat the grounds.

 

[matt youwin]

Sorry I should have been more specific, the reamp ground lift does work, and reduces some hum, but doesn't eliminate the problem noise I'm talking about.

Thanks for the tips though, lots to think about. I'll try the increasing the buffer, I think it was only set to 512. Will also look into the polarity on the interface output and the grounding on the PC.

Cheers

 

[Metaltastic]

It's a ground lift, just went through dealing with one myself when reamping (had both hum and hard drive noise), get an isolation transformer like this sucker, put it between your interface and your reamp box, and you'll be gold! Don't bother with all those annoying things like switching outlets, changing buffers, etc., it's just more hassle than it's worth when an iso transformer is a pretty cheap investment that will serve you well in many applications to come.

 

[2000ContourSVT]

Yeah that definitely sounds like ground loop hum to me. I don't have any ground loop troubles myself but I do run a Boss NS-2 after the reamp box to cut down on amp noise from the high level of volume. You might try that and see if that helps a little if you have some sort of noise suppressor already available.

 

[TheWinterSnow]

It's a ground lift, just went through dealing with one myself when reamping (had both hum and hard drive noise), get an isolation transformer like this sucker, put it between your interface and your reamp box, and you'll be gold! Don't bother with all those annoying things like switching outlets, changing buffers, etc., it's just more hassle than it's worth when an iso transformer is a pretty cheap investment that will serve you well in many applications to come.

i mentioned to change the buffers regarding the popping and clicking problem, which is a sign that their is too much strain on the PC and you need to up the buffering, a who different issue to the ground lift problem.

 

[Metaltastic]

Ah, my bad, I just skimmed over the responses

 

[TheWinterSnow]

and matt did you process what i said about using balanced cables, are you using instrument jacks from your interface or are the outputs XLR? i know off hand that if you are using an unbalanced cable into your box, that ground loop won't do much with cutting the noise becuase the ground is going to your cold (-) connection which could create the noise right there.

 

[matt youwin]

Cheers metaltasitc I'll look into an iso transformer

TWS - I'm coming straight out of my interface with a TRS-XLR3M adapter similar to this:

then an XLR cable to the reamp box so I don't think that's the problem, cheers though.

 

[TheWinterSnow]

Cheers metaltasitc I'll look into an iso transformer

TWS - I'm coming straight out of my interface with a TRS-XLR3M adapter similar to this:

then an XLR cable to the reamp box so I don't think that's the problem, cheers though.

i was just making sure you are using TRS and not TS, since you are using TRS then you have an effective ground.

look into that iso transformer that should be your best bet at separating your computers ground loop noise that is being sent through the cold terminal.

 

[MetalJonesy]

i had quite alot of hum when reamping, so i spent a few quid on the best behringer thing ive used, a HD400 hum destroyer, great for the money!

 

[TheWinterSnow]

I had about the same kind problem last week, if you can with xp, adjust your minimal processor state to something like 50% while reamping, ( I did it with vista and it worked for me), for me the hum was coming from my processor!

i had quite alot of hum when reamping, so i spent a few quid on the best behringer thing ive used, a HD400 hum destroyer, great for the money!

this kind of hum that you are all having is coming from a ground loop from the computer, they digital noise is coming from the 1's and 0's of the computer and the interface is converting that digital signal into sound that is leaving your interface. Since it is a ground situation an iso transformer or a noise reduction system will do if the ground lift on your DI does not work.

 

[somewonton]

I hear allot of suggestions. No conclusions. Beuller?