E1DA Cosmos ADC teardown

[TNT]

Better if the designer could explain whats the problem with the Commons ADC... but he doesn't seem to think its of any use so not so inclined to discuss the matter as it turns out... maybe a few has some need that he don't have...

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[pkane]

Better if the designer could explain whats the problem with the Commons ADC... but he doesn't seem to think its of any use so not so inclined to discuss the matter as it turns out... maybe a few has some need that he don't have...

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When I first reported this to @IVX, he thought the issue might be insufficient power due to Intona consuming some of the USB-limited current for its own, internal purposes, dropping the voltage or not providing enough current to fully power Cosmos ADC. It would seem that the extra USB power supply in HS01 should solve this if that's the issue, but it doesn't.

 

[TNT]

I externally fed the Cosmos via the cheap isolator trying to get it working - so no, not that. The power feed worked because the Cosmos started up with just the board and a bank.

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[thanospl]

Hello, sorry to ask. is that ADC work with MacOS? Can record directly on any application? Thanks in advance

 

[TNT]

Yes it works.

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[thanospl]

Thanks a lot

 

[IVX]

Sorry for the slightly Offtopic but I can't resist Actually, it was measured with Cosmos ADC+APU.
The THD+N performance Cosmos DAC proto V1.4 [email protected] 0dbfs 9.7Vrms balanced output. Different MCLK settings show the compromises between noise and harmonics distribution, pretty much the same as for ES9038 - lower MCLK = cleaner harmonics but higher noise. The dynamic range is 136.7db(A), crosstalk -144db@1kHz. This is purely DAC output, no LPF is involved, just ES9039Pro + one composite opamp for the left, and another one for the right channel.

 

[trl]

-128dB...-130dB THD+N? Is this stunning result or what? Where did you got the sinewave files to play it, please?

Is the Cosmos DAC will appear on the market and at what approx. price, please?

 

[IVX]

Hmm, what kinda file, as you can see this is a plain REW GEN.

 

[Music1969]

This is purely DAC output, no LPF is involved

When you incorporate LPF, can you do linear sweep from 0 to 22.05 kHz and show wideband plot ? Like 1MHz ?

Also - Cosmos DAC chip is running in synchronous or async mode ?

Two separate clocks in synchronous for 44.1k and 48k base rates?

And will you support 1.5MHz PCM input ? For those doing digital filtering in software

 

[IVX]

I'm thinking, should I add the LPFs there if ES9038Pro looks so clean already? THD+N -130db and THD -144db look like it's Ok without LPF, and cheaper.
It is async mode with a single clock, 768K is the max sample rate. Also, I can add the USB ISO the same as for a new Cosmos ADC ISO with a separated USB DATA connector(fixable by a screw) and USB Power connector. However, all these things affect the BOM cost.

 

[Music1969]

I'm thinking, should I add the LPFs there if ES9038Pro looks so clean already?

Need to see what is happening past 30kHz to determine if clean?

Do you have equipment that can show up to 1MHz ? With linear sweep 0-22.05kHz ?

 

[IVX]

Need to see what is happening past 30kHz to determine if clean?

Do you have equipment that can show up to 1MHz ? With linear sweep 0-22.05kHz ?

I guess you misunderstood about the LPF I mentioned. The LPF in the I/V stage is in action(at Fs/2), but the initial idea of Cosmos DAC was to use additional LPF at 1kHz to wipe out the residual noise and harmonics to use as low-distortion sine gen.

 

[Music1969]

I guess you misunderstood about the LPF I mentioned. The LPF in the I/V stage is in action(at Fs/2), but the initial idea of Cosmos DAC was to use additional LPF at 1kHz to wipe out the residual noise and harmonics to use as low-distortion sine gen.

Ah yes.

Doesn't look like LPF at 1kHz is required.

But if you can do wideband linear sweep later and share, that would be cool !

 

[trl]

Hmm, what kinda file, as you can see this is a plain REW GEN.

Thanks! What about the other question from the end, please?

 

[IVX]

Thanks! What about the other question from the end, please?

Do you mean cost? I have to decide if I need here USB ISO(ISOUSB211 I can buy today for $20 as an example), and 1/10Khz LPFs.
PS: a couple of days ago I got msg from our discord user with the wish list for $500 budget:

FYI, I would happily pay 500 USD for:

- Cosmos DAC
- Stable reference voltage for the DAC
- Cosmos ADC
- 1 usb interface with the same clock
- XLR+BNC+BANANA interface, audio-precision style
- Input protection with a high impedance on the ADC
- Ranging
So I guess the only Cosmos DAC should be no more than $100 or so

 

[miero]

How about isolating the I2S bus? That could be cheaper than isolating the USB, but it adds a separate power requirement for the "clean" side.

 

[IVX]

Cosmos line uses 90x50x1mm PCB.

 

[Atanasi]

So I guess the only Cosmos DAC should be no more than $100 or so

From the European perspective, it is easier if an item's price is at most 150 EUR, not including taxes or shipping.
In this case, the sale can take advantage of Import OSS, which means that import taxes are prepaid and the customer doesn't have to make a customs declaration.

 

[Music1969]

Cosmos line uses 90x50x1mm PCB.

Scaler is coming first right?