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Old 11th March 2011, 06:15 PM   #401
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Yeah, exactly what I did other times for similar problems ...

Do you know where buy it at better price?

Marco
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Old 11th March 2011, 06:24 PM   #402
claudio is offline claudio  Italy
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At the time I build the Jig, I found that connector in my town local store. I paid a couple of euro for a 2x50 pins.
Also some computer cables could be adapted, the ones used to connect Hard Disk, but lot of work is needed and I am not sure if it is worth.

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Old 11th March 2011, 06:36 PM   #403
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Yes, floppy disk cable and connector is 34 pins ...

I have also found ASSMANN A-BL254-DA-xxxD series.

Thanks for your advises.

Marco
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Old 11th March 2011, 06:49 PM   #404
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Just wondering ... (without re-reading this entire thread) ...: Has anyone tried to evaluate any of the standalone (non-PCI or PCIe) sound cards with the gadget?
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Old 1st April 2011, 11:51 AM   #405
AndrewL is offline AndrewL  United Kingdom
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There was some work on one of the EMU cards, there's a couple of threads on this forum about it.

I would love to hear some input on this subject, what is the best sound card?

I made some interesting findings last night that fit nicely with this question.

What I discovered was that there is a distinct difference between the sound card outputs when testing on monitor/loopback. I noticed this when generating a measurement baseline which I always do before hooking up the amp under test.

One output has more higher level harmonics on it.

I use a ESI PCI card, by its nature a PCi card is on a very small PCB, and all teh outputs are very close together.

I do wonder if there's some crosstalk? Will an external box do a better job as everything is less crammed in?

Now this difference doesn't bother me as I can only use one channel at a time for measurement but it is interesting none the less since it is the output channel farthest from the sound card's input channel that is markedly better and matches the images I posted earlier.

So, if you can imagine I am using sockets 1 and 4 on the card for in and out left to right, so red channel out and white channel in - this nets maximum physical separation and the best results.

Even better results by far, however, are with the sound cards generator turned off completely and using the generator signal from a distortion analyser.

At that point the FFT reads -115db/0.0002% THD @ 2v RMS, isn't that almost as good as 20K's worth of Audio Precision, at least on FFT terms?

I suspect, I am seeing crosstalk between the cards input and outputs.

Of course, could it be the generator in my analyser is just better than the one in sound card?

Andrew
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Old 1st April 2011, 12:25 PM   #406
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Quote:
Originally Posted by AndrewL View Post
Of course, could it be the generator in my analyser is just better than the one in sound card?

Andrew
In the little bit of time I have put in with measurements, I have found this to be the case. My Saffire was pretty bad, a lot of improvement with MAudio Profire 610, but still, the analog output needs to be turned down to a 'sweet spot' where is produces the least distortion.

My best results are coming from using SPDIF output to a Behringer DCX2496 transformer coupled output. The sound card inputs appear better than the outputs.
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Old 1st April 2011, 03:58 PM   #407
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Quote:
Originally Posted by AndrewL View Post
... I would love to hear some input on this subject, what is the best sound card? ...

What I discovered was that there is a distinct difference between the sound card outputs when testing on monitor/loopback. I noticed this when generating a measurement baseline which I always do before hooking up the amp under test.

One output has more higher level harmonics on it.

I use a ESI PCI card, by its nature a PCi card is on a very small PCB, and all teh outputs are very close together. ...
Guessing :

* Electronic and/or physical distance from output (L) verses output (R) from the PC's power supply are the same? Different?

* PCI Card ground plane orientation as shield from PC processor(s) noise for output (L) verses output (R) is the same? Different? (Or does the PCI Card even have a ground plane or other shielding?)

Quote:
... I do wonder if there's some crosstalk? Will an external box do a better job as everything is less crammed in?

Now this difference doesn't bother me as I can only use one channel at a time for measurement but it is interesting none the less since it is the output channel farthest from the sound card's input channel that is markedly better and matches the images I posted earlier.

So, if you can imagine I am using sockets 1 and 4 on the card for in and out left to right, so red channel out and white channel in - this nets maximum physical separation and the best results. ...
Ah Ha! ... Eureka ...

Quote:
... Even better results by far, however, are with the sound cards generator turned off completely and using the generator signal from a distortion analyzer. ...
Even more crosstalk potential if the onboard sig. generator outputs to all ports simultaneously ... The onboard sig. generator may not be very well thought out and an added nuisance. (Could it be defeated entirely, permanently? It may be adding stray capacitance, even when defeated.)

Quote:
At that point the FFT reads -115db/0.0002% THD @ 2v RMS, isn't that almost as good as 20K's worth of Audio Precision, at least on FFT terms?

I suspect, I am seeing crosstalk between the cards input and outputs.

Of course, could it be the generator in my analyser is just better than the one in sound card? ... Andrew
Mmmmm ... As for external sound cards, separation from the PC's switching supply is probably a significant plus, even if bus powered through a USB or FireWire connection. I can't find much online about Power Supply Rejection on stand alone sound cards (= PSRR at the chip level), but intuitively would imagine that it would be better on a longer cable than not ... and the inclusion of RF ferrite lugs might also be a plus.
Click the image to open in full size.

Last edited by FastEddy; 1st April 2011 at 04:02 PM.
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Old 19th April 2011, 12:47 AM   #408
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Default Please help - high distortion

I have the PMillet tester, an EMU 1212m card and a capable dual core machine running Windows 7 with 4GB RAM. I am running a licensed copy of AudioTester 3.0c. Left channel Input only - but some garbage is showing up in the right channel - no idea why. Everything LEFT is panned LEFT. I get no response in the RIGHT channel from PatchMix - yet it appears in AudioTester.

I cannot achieve low distortion < 0.6%! Not even through loopback. It just looks awful. I have played with the settings in PatchMix, followed various guides in this thread and on the web - and still no joy! Do you think I have a faulty card? Something else to try? If I turn off the Sound Generator, my noise floor is -130dB - just fine for me.

Also, I tried to do the calibration with a separate audio generator that can output +/-15V (pk-pk). However, when I try to use the PMillet tester, I can never achieve max input because it overloads the front end before I get to about 40% in Audiotester. I am forced to drive the 1212m directly using an unbalanced source, monitoring the RMS value on an HP 3400A. I am not confident that I am getting accurate calibration.

And one more thing...when I run THD power tests, I get two warnings about high levels (expected), but then nothing happens. The test does not start. What the heck is going on?

Please help soon, I have a customer waiting for his design and I can't give him accurate THD levels.

EDIT: I just unplugged everything from the soundcard and I get the same results. Someone please tell me - step by step - how to configure this stupid PatchMix so it works. I'm on a hard deadline!

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Last edited by EnvisionAudio; 19th April 2011 at 12:59 AM.
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Old 19th April 2011, 02:19 AM   #409
iko is online now iko  Canada
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Quote:
Originally Posted by AndrewL View Post
I would love to hear some input on this subject, what is the best sound card?
Andrew
This card is quite good, but you may have found the thread already:

DIY Analog-to-Digital Converter project.Audio measurements tool
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Old 19th April 2011, 02:37 AM   #410
SY is offline SY  United States
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I don't know PatchMix, but I do know that you've got a little crosstalk (really, it's not bad at all!) and that there's something interrupting the channel you're testing. What window/apodization are you using?

Just for grins, change the test frequency slightly. 998Hz, for example.
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