strange noise

[aviator]

hey guys
im getting a strange noise while recording on my laptop hp 8540w
im using zoom g2.1u (usb connection)
even if the sound level on zoom is on min, i still get this noise
i also tryed to work on batteries, but notings changed
tnx for your help

noise.mp3

(78.31 KiB) Downloaded 617 times

[bgravato]

If you connect your headphones to the g2.1u's headphones output do you hear that noise too?

[billw58]

If you do a Plot Spectrum on the sample you can see that there is 1000Hz and all its harmonics (up to 10 kHz). Do you get this noise when the Zoom is not connected? Do you have any other USB audio devices you can connect and do a test recording? This could be a limitation of the USB connection on your laptop.

Strangely, there is also a large component with a fundamental of about 5.5 Hz in the form of a triangle wave. It would be nice to track down where that is coming from as well.

-- Bill

[bgravato]

Strangely, there is also a large component with a fundamental of about 5.5 Hz in the form of a triangle wave. It would be nice to track down where that is coming from as well.

A couple of months ago I monitored (on an oscilloscope) the signals on the usb ports of my macbookpro and I think I saw that kind of triangle wave on one of them. I don't remember what frequency, but it was hight frequency. There's a lot of high frequency noise on the usb ports of computers... But the signal coming from the external usb devices is digital so it shouldn't matter, unless there isn't proper filtering on the usb device and some of that noise is going on a feeback loop through the usb cable...

[aviator]

If you connect your headphones to the g2.1u's headphones output do you hear that noise too?

no i don't hear that nose on on the headphones

If you do a Plot Spectrum on the sample you can see that there is 1000Hz and all its harmonics (up to 10 kHz). Do you get this noise when the Zoom is not connected? Do you have any other USB audio devices you can connect and do a test recording? This could be a limitation of the USB connection on your laptop.

when the zoom is not connected there is no noise, so when i use laptop mic, the sound is clean
sorry i don't have any other usb mic to test, but i think there is not a problem in zoom, but in laptop
when i was recording using zoom on the PC there was no noise
maybe is has to do something with CPU

[billw58]

Do you have access to a USB hub? Normally we don't recommend using one, as they sometimes (often?) cause more problems than they solve - the hub can introduce time delays which then cause dropouts in the sound.

In this case it might be worth trying a USB hub that has its own power supply (rather than relying on the USB port in the computer to power the Zoom mic).

-- Bill

[bgravato]

Could be too much noise from the usb 5V that is not being properly filtered by the device.

Can you power the device from an external power supply?

[aviator]

i have powered zoom from external power suppy but there are still no changes
only possible solution yet is to remove noise with noise reduction tool
i record with nero sound editor
here is the result:

test.mp3

(464.67 KiB) Downloaded 418 times

[steve]

My (fairly confident) suspicion is that the noise is generated by the Zoom G2. The type of noise sounds fairly typical (though rather too loud) of the type of noise generated by digital signal processors. When listening through headphones, or connecting to an amp, there will be analogue filtering to remove sub-sonic (very low) frequencies and high frequency digital noise, but when connected via USB this analogue filtering is not present, so it gets recorded. On many effects pedals setting the input gain quite high and then adjusting the output level down will minimise the noise level. Any remaining noise can then usually be dealt with effectively with either a noise gate or noise removal. I believe that the G2 has a built in noise gate which may (depending on design) solve the issue without the need for additional post-recording processing.

[aviator]

i still blame hp laptop, because my friend has also tried to record something on macbook pro and there was no noise...