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moresound
Loud Sun Studios
He is just a blow hard.
He is just a blow hard.
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zan1976
New member
just posted a sample of the noise, perhaps you can identify it
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funkyto
New member
I think that it could be ground loop, try with another usb cable, one with ferrite bead, also if you can try with another computer if the noise will be the same.
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danbortz
New member
ground loop maybe
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ecc83
Well-known member
I have tried a attach a RighMark analyser spectrum of that noise but I cannot seem to get it to work.
The spectrum is however very odd. It is a near classical 6dB per octave low pass filter (HF cut) starting at a low frequency of 100Hz and falling to -60dB at 10kHz, There is also a big peak at 50Hz some 40dB above 100Hz! This 50Hz peak indicates to me either some serious magnetic coupling, power supply hum would be 100Hz, or most likely a hum loop.
Dave.
The spectrum is however very odd. It is a near classical 6dB per octave low pass filter (HF cut) starting at a low frequency of 100Hz and falling to -60dB at 10kHz, There is also a big peak at 50Hz some 40dB above 100Hz! This 50Hz peak indicates to me either some serious magnetic coupling, power supply hum would be 100Hz, or most likely a hum loop.
Dave.
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zan1976
New member
Yes I am, do you think I need external pre-amp? The sound card already has mic pre-amps.
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danbortz
New member
Probably a real stupid question...but are you using the phantom power switch? Last time I had this issue it was cured with an external pre-amp but I can't see why you would need one. Good luck
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ecc83
Well-known member
No, you should not need a pre amp. Instead buy a $20 digital multimeter and measure the phantom power!
Dave.
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danbortz
New member
Wouldn't think so...the unit should have pre capability or it would be a stupid design. Just sounds like more of a signal problem.
PRHunt
I void warranties
OP,
I suggest turning OFF all lights with dimmers.
With the sound clip attached earlier, was that with the mic plugged in?
As mentioned earlier, to assess noise inherent to a preamp or interface, you need to have the input closed (terminated).
By the way, is your local mains power supply at 50 or 60 Hz?
I suggest turning OFF all lights with dimmers.
With the sound clip attached earlier, was that with the mic plugged in?
As mentioned earlier, to assess noise inherent to a preamp or interface, you need to have the input closed (terminated).
By the way, is your local mains power supply at 50 or 60 Hz?
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zan1976
New member
Yeah, the mic was plugged in, here's one with the mic disconnected (can't hear much though).
Local mains power here in Greece is 50 Hz
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rhp
New member
please delete
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ecc83
Well-known member
True but the AI could be faulty or the XLR lead and +48 might not be reaching the mic.
Dave.
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ecc83
Well-known member
bouldersoundguy
Well-known member
The slope is nothing unusual. The 50Hz and the various harmonic products certainly look like line noise.
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ecc83
Well-known member
Why do you say the slope is not unusual please?
I have just run white noise(16bit .wav) thru RMA and got a dead flat 20Hz to 20kHz response.
The harmonics are weird, they are not 50Hz resultants.
I could not post an attachment of the flat noise this time even on my HP i3 w7/64. IE9 laptop which worked for the OP's noise albeit I got a huge picture when in other forums you get a discrete box at the bottom to open, sometimes a thumbnail. And why must you drag and drop? Easier to cut and paste for me especially from a stick in a laptop.
I have another lapotop with Firefox on it I shall give that a do!
Dave.
bouldersoundguy
Well-known member
Try pink noise or music. Pink slopes down pretty steadily and music often peaks around 100 or so depending on the style.
There seem to be response spikes at odd multiples of 50Hz: 250, 350, 450, 550, 750 and 950. Maybe I'm misinterpreting the graph.
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ecc83
Well-known member
Err? Pink noise falls at 3dB per octave (why it is not possible to generate it easily). I took the sample to be system noise and thus fairly "white" (my 2496 is). It IS common to see "one upon F " noise with a rising LF response but that only starts at about 100-200Hz, classic "transistor" noise.
You would expect 50Hz harmonics to land bang on 150,200,300 and so on...
Still! This all does not help the poor OP! I would like to track down that huge 50Hz peak?
Dave.
bouldersoundguy
Well-known member
There's not any real audio in that sample? I suppose I should have listened.
Well, I just generated a 50Hz sine and applied a distortion effect resulting in peaks at 150, 250, 350 and so on, sloping downward toward the HF. That seems a pretty good match for some aspects of the noise.
Well, I just generated a 50Hz sine and applied a distortion effect resulting in peaks at 150, 250, 350 and so on, sloping downward toward the HF. That seems a pretty good match for some aspects of the noise.