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lemon 23rd October 2012 04:52 PM

E-MU 0404 usb 2.0 and some "artifacts peaks" on left channel
1 Attachment(s)
I hope so to submit to the right discussion.

I use the emu like a measurement tool for measure dac's, amps e.t.c

I have a problem with the noise on left channel of my emu 0404.
There are always some "artifacts of peaks" at 8KHz, 10KHz, 12KHz and so on.
The right channel is without problem.

Because my english is not good, I have attached an ARTA noise measuring capture with external loopback (analogue line out -> line in), but the same happens and without any connection, only FFT record of noise.

I have seen the same behaviour and to another used emu 0404 usb at the same left channel with the same peaks!

Any suggestion what is the reason?

iko 24th October 2012 01:17 AM

1 Attachment(s)
Here, my usb 0404, so you don't feel so bad. :)

sidiy 24th October 2012 03:52 AM

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Same here. I get the same no matter what sample rate I choose (multiple of 44.1k or 48k).

...and not my only issue: has anyone managed to make it work with Windows7?

lemon 24th October 2012 09:34 AM

Yes, it works fine with Win7 on my laptop (beta driver for 32bit OS).

I see that there is the same behaviour and yours emu on the left channel.
But why only on the left channel and not to right?

There is must an explanation about this and must be a solution for this. A new one emu has no any problem to the left channel.

It has the same behaviour with all sampling rates, with 16/24bit resolution.

I have changed the last capacitors on the left input but with no success.

iko 24th October 2012 12:42 PM

Mine works with Win 7. I forget where I got the driver, might be the beta.

sidiy 24th October 2012 09:50 PM

Maybe it is a layout issue like some USB related traces close/under the left channel circuitry. I'll never know unless I open it....!

My W7 did not like the beta driver, but that was ~1 year ago so I should try again...

lemon 25th October 2012 09:14 AM

What are you meaning with: "it is a layout issue like some USB related traces"?

sidiy 25th October 2012 09:02 PM

It is just a hunch....Since the two audio clocks don't seem to be responsible for those bins (each is turned off when the other is used) there are two suspects left:
1.a USB controller (something with a 12MHz crystal)
2. (less likely) a DC-DC converter used to boost/make a negative rail for the analog supply

One of these is close to the left channel circuits managing to radiate some noise into them.
I always wanted to open it and see exactly what it is used inside, altough I'm pretty sure that everything is crammed on a multilayer board and identifying the cause will be next to impossible....:mad:

ScreamingLordByron 26th October 2012 07:40 AM

Maybe try a powered hub? A lot of EMU0204 don't have this problem.

qusp 26th October 2012 06:42 PM

sidiy, I agree with your deductions, it seems it cannot be audio related or it would be shifting with the frequency/bitrate. I actually think 2 is quite likely as well, but riding on the USB. another option is the MCU, which may also be running on a 12MHz crystal

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