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E1DA Cosmos ADC

pma

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So thanks to E1DA Cosmos ADC, I was finally able to measure distortion of my class A amplifier. ADC in mono 2-channel mode. H2 and H3 of the amplifier are close to -130dBr.

PM-A4_E1DA2chan_1k_15W_4R.png
 

pma

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PMA, are you sure if your REW works in ASIO 32 bits? Looks noisy like 16bits.
Yes I am. Below see the ADC noise and D10s-E1DA loop noise. ADC flat 22kHz noise is -123dBFS. With 16dB resolution you are 20dB higher. Do not forget to count with FFT length and number of averages. I work with usable settings, not to wait 1 hour to get seemingly nice noise.
The last plot is amp measurement compared to DAC-ADC loop noise all in dBFS. Also please take into account that the amp multiplies DAC output noise (2uV) by its gain (26 dB here, 20x) to 40uV. 20log(Vout/Vnoise) makes the limit.
 

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pma

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Ivan, no protection in front of R1, R2? That might be dangerous (ESD, overvoltage), what do you think.
 

1231rq32r1qw32r

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@IVX - How do I get the ADC to work in stereo mode in MacOS?

edit: same way as in Windows. Reduce the mixer volume.
 

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mansr

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Why are you abusing the volume control like this? Can't you provide on/off toggles instead?
 
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mansr

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I was hoping for a slightly more elaborate answer. Is it a limitation of the USB interface chip?
 

Atanasi

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I was hoping for a slightly more elaborate answer. Is it a limitation of the USB interface chip?
USB mixer interface supports multiple on/off toggles, but I suppose Windows would not map those to any UI without a special driver. On Linux, the alsamixer tool allows toggling.
 

1231rq32r1qw32r

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Correct, but where is the center of Macos volume slider I'm not sure. It could be important for turning On the internal DSP of Cosmos ADC to RIAA EQ. I've prepared the new FW
with STEREO RIAA mode in the center(+/-10%) of the Windows slider.

This is as close to centre as MacOS allows
 

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Atanasi

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This is as close to centre as MacOS allows
This seems like the same volume curve as the Windows standard driver: 0.5 corresponds to -20 dB. USB mixer volumes are set internally in dBs, so it is the comparable number between systems.
 

pkane

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I don't know how I can add any physical button to the existing device. Also, I don't know how to add a software button to the windows driver, so I can only use a funky way to add a new control.

Couldn't you use the same mechanism used by the tweak app to communicate with the ADC in an app instead of the driver? Doesn't matter if this is added to the tweak app or becomes a separate, stand-alone app with only a button or two. This should give you plenty of room to add new EQ settings and any other features you might think of in the future :)
 

1231rq32r1qw32r

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Couldn't you use the same mechanism used by the tweak app to communicate with the ADC in an app instead of the driver? Doesn't matter if this is added to the tweak app or becomes a separate, stand-alone app with only a button or two. This should give you plenty of room to add new EQ settings and any other features you might think of in the future :)

No, I thought this volume thing was silly at first but now I understand that it allows it to work simply across all platforms. I do not want to drag out my old PC laptop to have to change settings.

The current system is not intuitive, but it works very well once the user understands it.

I think you underestimate the work involved in maintaining and supporting applications - especially for Windows, MacOS and Linux.
 

pkane

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No, I thought this volume thing was silly at first but now I understand that it allows it to work simply across all platforms. I do not want to drag out my old PC laptop to have to change settings.

The current system is not intuitive, but it works very well once the user understands it.

I think you underestimate the work involved in maintaining and supporting applications - especially for Windows, MacOS and Linux.

As someone who's created and published software for different platforms most of my life, I understand the maintenance aspect as well as the next guy. Heck, in fact this volume behavior by Cosmos ADC forced me to make changes to my own software! And you're talking about the work involved in maintaining applications! :)

I also use multiple platforms for audio and measurements, so understand the need for a cross-platform operation. What I find annoying is that I can't defeat the volume-control behavior of Cosmos ADC when I want to, and this often trips me up in my measurements. I'd much rather have a choice to turn this feature off and set one specific mode when I'm doing measurements, and another mode when I'm recording audio. At the moment, I have to be very careful to set the correct volume slider setting and this is made worse because I switch between multiple laptops, PCs and Mac computers and even different versions of Windows multiple times a day.

Here, I did it :)
1655466506766.png
 
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1231rq32r1qw32r

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As someone who's created and published software for different platforms most of my life, I understand the maintenance aspect as well as the next guy. Heck, in fact this volume behavior by Cosmos ADC forced me to make changes to my own software! And you're talking about the work involved in maintaining applications! :)

Exactly, so you'll see why one man, who designs the hardware and writes the current application, doesn't have time or the inclination to do more.

How about a suggestion - an addition to the current COSMO application that forces the unit to stay in a single mode regardless of volume? For example, 'Force Stereo' / 'Force Mono' / 'Volume Auto Select'?
 
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