Getting clean output from USB soundcard and/or laptop: my experiences
Nov 10, 2008 at 4:05 PM Thread Starter Post #1 of 7

phalanger

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I haven't been reading along these boards much lately so it's possible that the information in this post is common knowledge to everyone here, in that case, just ignore and/or delete the post and excuse me please
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This is about how i got 100% noisefree audio output from laptop through my E-MU 0404 USB soundcard.

Lately I've been doing some home recording and noticed that even though under normal circumstances the sound was just fine, but when not playing any music and the amp volume on full, I got audible static, clearly produced by the laptop (lcd screen, harddrive). After looking around some I found the suggestion of *not* using the notebooks powersupply plugs grounding. In other words convert the 3 prong connector to a nongrounded 2 prong one.
The result of this was very good, the display and harddrive feedback were gone, 95% of the noise was. But when turning the amp to 80% or more volume, there was still a soft high frequency noise. Nothing you'd ever encounter in real use but when i know its there it bugs me.

So what i did next was remove/isolate the grounding wire from the usb cable between the notebook and the E-MU. This alone did no good, but then i also shielded the metal outside of the usb connector (on emu's end), using tape. After both the grounding wire and the metal casing to the plug were isolated, the noise was fully gone.
The audio from the pc is now dead quiet wether the volume is on 0% or 100% on the amplifier. More quiet than the output of my cd player, which creates a soft noise at full volume, possibly due to the long and cheap cable i use for the cd player atm versus the short, fancy high end interconnect the emu has.

Like I said, I don't know if this information is useful to anyone here, but since it wouldve saved me some pondering and trial and error, I figured I'd just post it and may or may not be of use to someone.

Cheers, phalanger
 
Nov 10, 2008 at 11:35 PM Post #2 of 7

blynch1

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I'm thinking about getting a 0404 so I may need to do this mod soon. If you had pictures showing which contact you removed and where you taped that would be helpful.

Besides this power problem, do you have any complaints with the 0404 as a dac?
 
Nov 11, 2008 at 5:24 PM Post #3 of 7

phalanger

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The ground pin is the one on the bottom left, on the EMU's end of the usb cable. the other contact point is just the metal/gold outside of the usb plug. I used 'painter's tape' to cover them both. You could cut the black wire to achieve the same but cutting open usb2 cables is not such a great idea.

You could probably isolate off the + power pin aswell but that wasn't neccesary for me. The 0404 doesnt use power from the usb cable at all, has its own power adapter. One would expect the grounding wires to not be hooked up to anything cause it only uses the data line from usb, but for some reason it does make its way into the e-mu circuitry.

And no, no complaints about the 0404 at all otherwise. It has a very good DAC onboard and a pristine sound. I A/B'd it with my philips bitstream cd player and it atleast equals it as a source, probably beating it. also has a good quality phones-out, output for L&R comes from 2 mono outputs for better separation (can be used as balanced output also).
Good Hi-Z inputs for guitars/microphones etc. And being external helps for SQ. It's very good value for the price.
 
Nov 15, 2008 at 1:03 AM Post #4 of 7

blynch1

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Got my 0404 today, tried to tape off those grounds but it did not work. When I tape off the outside of the usb plug on the emu's end the computer no longer detects it. I could cover up pin 4 but that made no detectable difference. I guess it is no big deal, as the static is heard only with the volume up essentially all the way with no sound playing.
 
Nov 16, 2008 at 1:26 AM Post #5 of 7

phalanger

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Strange. Are you sure your tape covering didnt shield off too much or made the connector go in such a way it fails to make another contact point? It was a bit messing around for me, have to use pretty thin tape or the usb cable fit will be too tight.
You should also be able to do it on the computer-end of the cable ofcourse but soundcard's end is preferable for purist reasons :p

But yeah the actual level of the noise it picks up over the usb is fairly low and not noticable at all in normal use. I've had the e-mu for months and didnt realize it until last week, when optimizing my setup for some recording stuff. But you did experience the same noise then, when volume of amp full up? Noise influenced by components of the computer?
It's a little flaw on the otherwise awesome 0404 imo, because as my shielding proves its clearly not neccesary. Ive had no issues of the unit not being recognized or fallouts or any other problems.

So it depends on how 'anal' you are about clean signals I suppose. it's indeed not of the magnitute to be noticable when listening to music.
I hope you're thoroughly enjoying your new purchase meanwhile? It's one of the most satisfying purchases I've made in a while, the DAC and ADC are just excellent, upto 192k 24bit, seperated optionally balanced outputs, digital i/o, MIDI and 2 very nice multiuse Neutrik jacks for mics, guitars but also line-in (i didnt realize this last option until recently
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Combine that with a very decent builtin headphone amp, direct monitor, external from pc and powersupply, and you have yourself a pretty unbeatable deal for the price imo
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(and i dont get paid to say that, i wish :p)
 
Nov 16, 2008 at 6:14 AM Post #6 of 7

blynch1

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I swear I was hearing the noise at full volume, but I just checked now and there is nothing-so I guess I don't need extra shielding.

I'm pretty happy with the emu. The headphone jack is quite good and is definately acceptable till I get a dedicated amp. I went from getting terrible listening fatigue with the SR225s and the x-fi sound card to little to no listening fatigue now. I'm guessing a cleaner sound has everything to do with that.

However, these drivers are killing me in Vista. I hope they release some proper drivers someday. The sound will just randomly cut off now and then.

For music listening is it best to set it to 16bit 44100Hz in the windows digital output options?
 
Nov 16, 2008 at 10:51 AM Post #7 of 7

phalanger

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Just set output to whatever your source material is. So for music that came from CD, yeah 16bit 44k1. Resampling is only useful if the DAC has to resample it to 48khz orso (emu wont have to) and/or the soundcard has such lousy conversion that you want to do it with software (not the case either)
 

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