What is this NOISE?!

[Hegs]

Arrggh.. Every time I plug my condenser (studio projects b1) into my Alseis i/o2 it erratically gives me these weird background noises (as well as clicks, pops, cutouts). The problem is exacerbated ten fold if I move the mic while it is on, even a very slight tremble. It also exhibits these problems when I use the mic with my Yamaha aw16g workstation.

The wierd thing is I have another SP B1, and it does the same thing. Iv also tried diffferent leads, problem still exists. If i use a sm57, no problem. wtf!

Iv uploaded a sample of this noise, the mic just lying stationary on my bed. Notice at about 7 seconds there is a sound that resembles a stomach rumbling...its very erratic but there have been times when this noise gets reaally loud and drawn out.

any help much appreciated, im totally mystified!!


NOISE:
http://rapidshare.com/files/399976915/noise_.mp3.html

 

[dastrick]

Strange. I have an SP B1 and it works great.




Maybe aliens are living in your microphones???

 

[RAMI]

Sounds like a bad cable.

 

[dastrick]

Sounds like a bad cable.

That's what I thought at first, but he said that he's tried different cables with the same result. And also said that his SM57 doesn't do it.

Maybe it's something fishy with the phantom power? Do you have another condenser mic to try?

 

[RAMI]

That's what I thought at first, but he said that he's tried different cables with the same result.

You're right, I missed that.

Iv also tried diffferent leads, problem still exists.

My next guess is something to do with the phantom power. Is it battery powered phantom power?

 

[Chili]

I don't know what the stomach rumbling noise is, but the rest of the clip kind of sounds normal. A noisy room, air flowing, muffled by being on the bed. Condensor mics are much more susceptible to room noise than dynamics.

Can you post a clip of you moving the mic? Maybe there's some loose shielding inside the casing.

 

[Hegs]

thx for responses so far.. the phantom power is supplied via usb from my laptop. I did buy the Alesis from the USA and Im in Australia so I dont know if some sort of voltage issue may be present. (I know u guys use 120v we use 240V) but because its coming from usb as opposed to mains power this seems irrelevant.

unfortunately i dont have another condensor to try.. it just seems wierd that BOTH sp1s do this.. I dont think i ever used to have this problem. that background noise is not just ambience, there is low frequency noise going on there, which becomes particularly apparent after compression..

 

[Chili]

Ah, USB, that might be the problem there. Two things come to mind; 1) Your USB port is not supplying enough current to power the interface and mic properly. This is the most likely cause, or 2) there is noise coming off the USB buss and not filtered good enough before going to the phantom power source. If you can hear more noise when your hard drive is active, then this would be the case.

Can you use a separate power source for your interface?

btw, The fact that it is particularly apparent when you compress your audio is just the nature of compressing audio. It will raise the noise floor.

good luck,

 

[dastrick]

I'm with Chili. It's probably the USB. Try using the same setup on a different computer.

 

[theycallmebrown]

i agree that it is the usb. also, tell us more about your setup. do you have an external hard drive plugged in to usb as well? each usb hub shares power, if you are needing to supply power to anything else along with the mic both will be under powered and you run the risk of damaging both and the usb port. i work at a computer repair shop and i see it all the time.
if it is a laptop its hit or miss, but generally on a desktop any usb ports next to each other share power, and usb ports above each other have separate power sources... try moving things around on the machine.

 

[Hegs]

ahhh yes i think u may be onto it..

i have noticed that the problem seems to rarely occur when i start a fresh project, with just my interface plugged in.
The problem seems to escalate once i plug my midi into a usb port and start adding tracks and vst plugins. I can buy a power supply for my midi keyboard, but the alesis can ONLY run off usb. Is it possible to buy extrnally powered usb slots (which would then have to feed back into my laptops usb slots i suppose), and could this help?