E-MU 0404 usb 2.0 and some "artifacts peaks" on left channel - Page 3 - diyAudio
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Old 28th October 2012, 04:31 AM   #21
sidiy is offline sidiy  Canada
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The THD plots...it goes to show where the next improvements should be concentrated, now that I learned my way inside . More on this later.

Well, happy soldering for now! If someone manages to duplicate these results it will be reassuring. Just let us know!
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File Type: jpg THD_192k.jpg (110.9 KB, 385 views)
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Old 28th October 2012, 01:43 PM   #22
sidiy is offline sidiy  Canada
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I forgot to post the results for dynamic range. Still some little gremlins bellow -132dB or so...at these levels it gets complicated, we need to consider shielding , I think.
There is also a 12k component that appeared on the right channel, or I'm seeing it only now because everything is cleaned around. (see it in the previous posts with SNR and THD too).

On the downside my mod degrades the crosstalk, it is now down 3-4dB at 20k (~ -84 dB absolute), because the new wiring hovers above the right channel over a length of 3/4 inch or so...I don't really mind.
But I had to inform you...
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File Type: jpg DR_192k.jpg (130.7 KB, 358 views)
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Old 28th October 2012, 02:05 PM   #23
qusp is offline qusp  Australia
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wow that was a really crappy routing job... I wouldnt do that on breadboard...
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Old 28th October 2012, 05:36 PM   #24
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Quote:
Originally Posted by sidiy View Post
The THD plots...it goes to show where the next improvements should be concentrated, now that I learned my way inside . More on this later.

Well, happy soldering for now! If someone manages to duplicate these results it will be reassuring. Just let us know!
E-MU 0404 is workhorse interface for me. I've always considered bang for the buck performance out of the box as superb. For acoustically derived signals the left channel interference never concerned me; however is limitation in using interface for assessing performance of other circuits.

Your analysis, and proof by modification appears excellent, and will make nice science when duplicated.

I've certainly enough experience to perform modifications as detailed here.

Before going under knife and iron a few questions:

What are values of R151 and R167? And removing their resistances doesn't impact performance, why?

How do you come up with degradation in crosstalk?

In OEM condition with -1dBFS 1kHz input on right channel, loop antenna of left input picks up:

(click to enlarge)
2 crosstalk signal 1kHz right.jpg



and with signal left, right is tight:

1 crosstalk signal 1kHz left.jpg

So here at 1kHz right channel picks up about 15dB less signal from right channel, than left channel picks up from right channel. Is this good assessment?

If in your mod, black wire additionally connected from R110 twisted onto wire up to R108, would this form shield/balance common mode signal for possible improvement?
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Old 28th October 2012, 11:58 PM   #25
sidiy is offline sidiy  Canada
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Hi,

Quote:
Originally Posted by Barleywater View Post

What are values of R151 and R167? And removing their resistances doesn't impact performance, why?

.................

If in your mod, black wire additionally connected from R110 twisted onto wire up to R108, would this form shield/balance common mode signal for possible improvement?
R151, R167 are zero ohm jumpers. There are also two of these for the right channel (R143, R147). They include these locations as a precaution in case there was ringing on the anti-glitch capacitor or to make an attenuation pad + 1st order LPF (when combined together with the resistive part of the ADC's input impedance). Apparently they decided that there was no need for these which served my purpose well
It is also a hint that they did not spent too much time in development, making a second run of the layout after the prototyping phase.

About the wires: I twisted them to ensure mechanical stability and minimal loop area. It looks like the black wire is coiled around the yellow, that is because the yellow is stiffer. About the segment of yellow wire that runs alone...keep it short and running close to the board - there shouldn't be any problems there.

About the whole crosstalk issue, let me run a test first, my external cables are kinda creepy...(pieces joined togheter)
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Last edited by sidiy; 29th October 2012 at 12:06 AM.
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Old 29th October 2012, 12:10 AM   #26
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Zero ohm jumpers obviously not an issue.

Any precautionary pointers on opening the case and getting to the target?

Regards,

Andrew
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Old 29th October 2012, 02:30 AM   #27
sidiy is offline sidiy  Canada
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As I remember:
The chassis separates in two; do this first. You can pull out the knobs later. Careful with the ground lift switches as you slide the two parts.
You don't need to pull out the knob for Direct Monitor level. The other 4 are a ...ch! Lift them slowly with a small screwdriver.
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Old 29th October 2012, 12:18 PM   #28
lemon is offline lemon  Greece
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sidiy, your solution duplicated with success!
Very nice work, very nice procedure!
Bravo!
Now the left channel is better from right.

- What about with earthquake in Canada? It was 7.7 (Richter scale)
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Old 29th October 2012, 12:32 PM   #29
iko is offline iko  Canada
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Argh! you guys, now I thought I was done taking my 0404 apart!

sidiy, well done!

Earthquake? That didn't do anything, but we're expecting some sort of bad storm coming to the Eastern coast.
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Old 29th October 2012, 01:08 PM   #30
lemon is offline lemon  Greece
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The left channel working very well. Many thanks to sidiy.

THD 0.00092%, THD+N ... 0.0015% (HeadPhone loopback, 24bit/48KHz sampling).

Ikoflexer for us (Greek) the 7.7 is a major earthquake with a lot of damage and lost in human beings, except if the center of earthquake done in the sea (with deep level).

You are afraid for tsunami, if I understood well!
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