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Old 22nd December 2012, 04:26 PM   #61
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I changed the HEF4517 for a CPLD (XC9572XL) to split the i2s into left and right now 96K is not a problem but for 192k the frames need to be 32f or data input in the simultaneous format, I have seen some reports of the latter being superior but I need to figure out how to best invert the msb in a serial data stream before I'll attempt it.

I have also tested an amanero async usb to i2s module in the converter with Jtest (using arta to generate the testfile) and attached here are the measurements,

I also tried the amanero with an improved low noise regulator (simple LTC6655 + pass transistor)
Attached Images
File Type: jpg DSC_0500m.jpg (249.6 KB, 311 views)
File Type: jpg DSC_0505m.jpg (109.8 KB, 296 views)
File Type: png amanero_44k1_org.png (95.2 KB, 290 views)
File Type: png amanero_44k1_LTC6655.png (69.4 KB, 278 views)
File Type: png cd_Spdif_cs8412.png (73.9 KB, 266 views)
File Type: png cd_noisefloor.png (72.4 KB, 88 views)
File Type: png noisefloor usb connected.png (67.4 KB, 73 views)
File Type: png noisefloor usb not connected.png (67.3 KB, 72 views)
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Old 23rd December 2012, 09:20 AM   #62
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Here are a pair of extra measurements, apears as the noisefloor I see is what I get when the amanero is actively recieving a data stream.
Attached Images
File Type: png amanero_44_1k_org_0dbFS.png (94.9 KB, 66 views)
File Type: png noisefloor usb connected_but signal is off.png (63.4 KB, 61 views)
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Old 23rd December 2012, 09:51 AM   #63
regal is offline regal  United States
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What soundcard are you using? Those are impressive measurements!
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Old 23rd December 2012, 09:59 AM   #64
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They were taken with a juli@.
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Old 11th May 2013, 09:46 AM   #65
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I did some mods to the amanero module I improved the decoupling by adding some 10uf/0603/6.3V in parallel with the original 100nF caps this extends the flatness of the decoupling impedance without to much effort. (see attached LT simulation based on models from muratas simsurfing web resource) notice the scales !

I also did a couple of slight trace cut jobs to separate the 3.3V plane between the atmel and the xilinx cpld. Im feeding the usb inteface backwards through the 3.3V ports by TL431 based shunt regulators as Im using it as a replacement for a CS8412.

Also I found why the noisefloor was degraded when fed through the amanero I had to export the Jtest signal as a .wav file from arta and play it back through foobar with wasapi plug in.

Then the noisefloor drops see attached image for jtest result.
Attached Images
File Type: png LTC.png (26.9 KB, 33 views)
File Type: jpg amanero_mod.jpg (503.7 KB, 56 views)
File Type: png amanero_44_1K_mod_WASAPI.png (37.3 KB, 59 views)
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