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E1DA Cosmos ADC

pkane, I have no ADI2 and can't confirm that. APx555b IMDvs level plot looks like that
SMPTE-Ratio.jpg
 
pkane, I just downloaded the Multitone to test IMD but can't see an adequate result yet, only -.25db when AP2700 shows -108db. THD+N AP2700 also shows quite different -6db from your result. Also, I think a bad idea to send 0dbfs volume command every time Multitone started. Cosmos ADC always switches on the MONO after that. BTW, AP2700 input level is -8.36dbfs but Multitone shows -6.7db.
2021-12-26_11-04-26.jpg
 
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IVX said:
pkane, I just downloaded the Multitone to test IMD but can't see an adequate result yet, only -.25db when AP2700 shows -108db. THD+N AP2700 also shows quite different -3.4db from your result. Also, I think a bad idea to send 0dbfs volume command every time Multitone started. Cosmos ADC always switches on the MONO after that. BTW, AP2700 input level is -8.36dbfs but Multitone shows -6.7db.View attachment 174640
Click to expand...

Just change gain from 0dB to something smaller. You can type in the number if it’s not in the drop down list.
 
THD+N 6db mismatch at 1kHz -116db. BTW, REW seems adjusted only for 1k THD+N and >1k or <1k THD+N are also wrong, at 100Hz AP2700 6-7db better! I gonna test Arta at 100Hz and 6kHz.
PS: no, regarding REW it was my mistake because FFT was 64k and spectral leakage made 100Hz THD+N so bad. At 6kHz REW shows 1db less THD+N vs AP2700, similar to Arta.
 
Last edited:
IVX said:
THD+N 6db mismatch at 1kHz -116db. BTW, REW seems adjusted only for 1k THD+N and >1k or <1k THD+N are also wrong, at 100Hz AP2700 6-7db better! I gonna test Arta at 100Hz and 6kHz.
PS: no, regarding REW it was my mistake because FFT was 64k and spectral leakage made 100Hz THD+N so bad. At 6kHz REW shows 1db less THD+N vs AP2700, similar to Arta.
Click to expand...
Hmm, not sure why you're getting a 6dB difference.

Here's the same signal being processed by REW and by Multitone. The differences appear to be within a fraction of a dB:

1640490132026.png


1640490207116.png



Now at 100Hz:
1640490340630.png



1640490368070.png
 
IVX said:
I have changed the "Gain" to -60db and next -120db, the Windows Volume slider anyway jumping to the 0dbfs every Multitone start.
Click to expand...

I see what you’re saying. The gain in Multitone is set by changing the amplitude of the generated signal, not by setting the system volume. Let me see if there’s something I can do to keep it from changing system volume to 0dBFS.
 
dac : spartan cue 48khz/s, trs 4v out
adc : cosmos adc 192khz/s, xlr 4.5v in

111.jpg
CUE performance was not the best, but there was no hump.

Oh, sorry.
Please hold for a moment. I found something a little different.
 
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Spartan cue is audiointerface.
cue out 48khz/s -> cue in 48khz/s.
cue out 48khz/s -> cosmos in 48khz/s
Even if I try again a few times, there are some hump. All settings are the same.
222.jpg
 
IVX said:
I have changed the "Gain" to -60db and next -120db, the Windows Volume slider anyway jumping to the 0dbfs every Multitone start.
Click to expand...
Hi Ivan,

Can you please test to see if this is fixed in Multitone v1.0.13? I found one place where the system volume was being set to 100% and removed it. If you start Multitone, it'll prompt you to update to the latest version or you can download the update from here: https://distortaudio.org/multitone.html#download-multitone
 
MC_RME said:
I don't see why you want to go back, the firmware seems stable and improved. It would be interesting though to hear which DC values are measured now 'in the field'. I gave my numbers already.
Click to expand...
A bit late to the party, but here's mine:
1640644905554.png

Around -56dB before FW upgrade and -95dB after.
pkane said:
Is there an AP IMD sweep for Cosmos ADC available? SMPTE 60Hz/7kHz 4:1?

I've done one using RME ADI-2 Pro FS as the source using my Multitone app and it shows a bit of the infamous IMD hump. Would like to confirm if this is the case with a better source:

View attachment 174631
Click to expand...
This is with Topping E50 as source (balanced, left channel only, E1DA Cosmos ADC stereo mode and 4,5V sensitivity):
1640645063447.png
 
IVX said:
View attachment 175038
Click to expand...

I see. Can you please try measuring using the Multitone-generated sine wave, instead? It's not at exactly the same frequency as the signal generated by the AP. This is in order to put it in the middle of an FFT bin. When calculating TD+N, the notch filter assumes that the frequency is at the same bin that was generated by Multitone, but in your test, it's not.

EDIT: Thinking about it, I'll add another test signal option, "External" to allow for external signal generators. This will help when using AP or REW or other external generators for testing.
 
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pkane said:
Is there an AP IMD sweep for Cosmos ADC available? SMPTE 60Hz/7kHz 4:1?

I've done one using RME ADI-2 Pro FS as the source using my Multitone app and it shows a bit of the infamous IMD hump. Would like to confirm if this is the case with a better source:

View attachment 174631
Click to expand...

I thought the infamous IMD hump was only exhibited by ESS DAC chips. Assuming your RME is an older unit like mine, it uses the AK4493 chip.
 
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