E1DA Cosmos ADC

[IVX]

Thanks for the answer... so if Wolf BP filtered the ADC output signal, he would have gotten the above result, correct?

Rather like this:

A linearity test is an archaic way to test ADC, maybe for 8-12bits is ok, .5db corresponds 5% of THD. THD vs level sweep is much more sensitive. Linearity+N has no sense to me.

 

[IVX]

Excuse my language barrier...
I just wanted to be sure that the differences were so small, It wasn't due to a very low number of harmonics being considered in the THD measurement (I believe it's generally considered up to h9).

(But also, only displaying h2 isn't very useful... you need at least up to h5 or h7... even and odd harmonics.)
;-)
(Maybe observing the chemical capacitors bypassed by an small MKP or better yet a styroflex or Teflon would be funny.)

I think the mentioned low.freq effect is shown here https://www.audiosciencereview.com/forum/index.php?threads/smsl-do300-dac-review.43780/post-1915440
Suppose it was an unbalanced connection, a balanced one has H3 -110db i.e. no effect. Anyway, 9822, and 9823 also have some hump of THD at < 100 Hz and 0dbfs. My test was performed at -6dbfs level to see -120db of THD, -.5dbfs test shows -110db of THD.

 

[IVX]

I found strange peaks on the FFT, around 1kHz +/-50Hz. Sometimes it is fairly low -160db or so, another time getting up to -150db. I place the ADC and DAC at another angle, and see some changes. So, I guess it is 50Hz products from the AC mains.

 

[megapro17]

The soldering service queue is 2 weeks.

Any progress?

 

[IVX]

I sent parts for soldering. Probably next week DM will be available.

 

[dgo42]

Sorry if my question is not new. Where will be DM version available to order? In DD-Audio Store?

 

[dgo42]

DM's frontend looks like this:

What Opamp you use? Does you take a look at ADA4945-1? It has output clamp possibility as ADC driver.

 

[dgo42]

@IVX I have Cosmos ADC iso since maybe two years. But after I think overvoltage glitch on the left channel I have now strengt behavior. Left channel has huge DC offset about +0.5V, but seems to work, on the right channel - no signal as expected. If I connect signal to the right channel - right channel works as desired, left channel shows always same signal but -6dB from the right. Maybe has you some idea what can be broken? It will be bad if ADC...

 

[staticV3]

If I connect signal to the right channel - right channel works as desired, left channel shows always same signal but -6dB from the right.

Sounds like your Cosmos is in Mono mode:


You can change modes via Cosmos Tweak utility (Windows only) and via UAC2 hardware volume level (OS agnostic).

Edit:
The clipping LED on the face plate also reports modes:
Blue=Mono, Green=Stereo.

 

[IVX]

@IVX I have Cosmos ADC iso since maybe two years. But after I think overvoltage glitch on the left channel I have now strengt behavior. Left channel has huge DC offset about +0.5V, but seems to work, on the right channel - no signal as expected. If I connect signal to the right channel - right channel works as desired, left channel shows always same signal but -6dB from the right. Maybe has you some idea what can be broken? It will be bad if ADC...

I think Static is right, MONO/STEREO mode was switched. However, if you really see DC over there, I suspect the input aluminum capacitor (220u/16V) has some leakage. It's not a big deal to replace.