E1DA Cosmos ADC

[LKA]

Now I have less than -120dB THD10k NICE, I'm happy

Viktor10k is quite noisy, output impedance 600R
Cosmos ADC input range 10Vrms, unbalanced mono

 

[staticV3]

@Abrise please use the default text color. I can't read anything:

 

[Abrise]

@Abrise please use the default text color. I can't read anything:
View attachment 289736

Sorry my preview was correct curiouly. I'll repost in a minute

 

[staticV3]

@Abrise

Progress

 

[Abrise]

@Abrise
View attachment 289737
Progress

Sorry again another 2mn more then this time

 

[Abrise]

I have been using the E1DA Cosmos for a few weeks now . Thanks to the measurements, I have already discarded to the recycle bin 2DACs and 1 amplifier . I also have had some good surprises when measuring old devices of mine. However being a non professionnal and considering the lack of extensive documentation, it has not been easy at all to get acquainted with this device. One have to read pages and pages of low SNR of forum posts.
Although all over I am very happy to have purchased this little tool , I want to share some of the difficuties I have met.

1- Grounding noise issues. This is not special to E1DA Cosmos but at the beginnig It was difficult to solve these problems. Now I always use an optical link from the battery powered laptop to the DAC which use a separate power, and the E1DA is powered by a power bank using a Y cable to the computer. I have studied the possibilty to buy an isolator but there is appparently no consensus on the right one to buy. Anyway it is certainly an interesting add-on for the Cosmos V2 that the designer is presently contemplating.

2-Mono vs Stereo . This also has been a terrible headache. When using the mono mode almost everything works straighfully. But when one try to use the stereo mode a lot of problem occur. In the main webpage it is clearly stated that Windows 10 doesn't need the driver but fortunately @staticV3 has written here "To change hardware volume via the Sound Control panel, this driver is required". . Also the same @staticV3 also kindfully recommended the use of Flexasio, Which I have done as ASIO4All is a nightmare. After having eventually and lately found these 2 statements and installing the driver and Flexasio together with its GUI, it's easier to use the Stereo mode. However I still cannot use Wasapi exclusive in REW, asio or not. Also now I can use RMAA in stereo using MME . I found it very useful for my comparisons it was not possible without the driver.

3-I am still comfused with the sensitivity settings. The sensitivities that I am finding are quite far from the official values. They are not the same in balanced or unbalanced mode.
But are they the same in mono and stereo mode ?
Here are the official values and what I have found

Sensitivity VRMS	VRMS measured
1.7	2,15
2.7	3,0
3.5	3.9
4.5
6.7	7,35
7.6	8,38
8.5
10

Are these variations normal ? What about mono, stereo, balanced, unbalanced, expected values ? Could we get them ?

 

[LKA]

How did you measure sensitivity ? The output impedance of a source counts a lot. I found the best way is to use a BNC T connector to calibrate the voltage levels (I use an unbalanced connection). In mono mode clipping occurs at -6dBFS, must take into account when calibrating in REW.

 

[Abrise]

Sorry again another 2mn more then this time

Hope it s readable by now I have removed all fomatting

 

[Abrise]

How did you measure sensitivity ? The output impedance of a source counts a lot. I found the best way is to use a BNC T connector to calibrate the voltage levels (I use an unbalanced connection). In mono mode clipping occurs at -6dBFS, must take into account when calibrating in REW.

I just put a value closed to 0dbfs at the input of the dac and I measure the ouput voltage with a voltmeter before connecting to E1DA. Then I put this value into REW arta window. There were no clipping

 

[LKA]

the voltage should be measured when the dac is connected to the cosmos adc

 

[Abrise]

the voltage should be measured when the dac is connected to the cosmos adc

Voltage output of a DAC shouldn't depend of the tool to measure it or to its load. It is not a power amplifier. Said differently if the Cosmos interfere with the voltage output of the DAC then we just don't know what we measure .

 

[staticV3]

But when one try to use the stereo mode a lot of problem occur

What kind of problems?

In the main webpage it is clearly stated that Windows 10 doesn't need the driver but fortunately @staticV3 has written here "To change hardware volume via the Sound Control panel, this driver is required"

To change the Cosmos ADC's mode via the sound control panel, you have to install the driver.
However, you can also use the Cosmos_Tweak utility to change modes, and that will work fine without installing a driver.

However I still cannot use Wasapi exclusive in REW, asio or not.

Please try using Java EXCL in REW. It's REW's native Wasapi Exclusive mode.

-I am still comfused with the sensitivity settings. The sensitivities that I am finding are quite far from the official values. They are not the same in balanced or unbalanced mode.
But are they the same in mono and stereo mode ?

The sensitivities are the same in Mono or Stereo, with a Bal or Unbal source.
They are the RMS voltage required at the ADC's input for -0.5dBFS output.

 

[LKA]

When the output impedance of the DAC is say 100R and you measure 1Vrms with no load, what voltage level does the Cosmos see after connecting the DAC ? (assuming 1.7V input range)
If you use 1Vrms as a calibration level (ADC), you will make a mistake.

 

[Abrise]

What kind of problems?

Ahahah you are right I should not express myself that way and go to the point. Unfortunately I didn't take enough note to report the issues scientifically .

To change the Cosmos ADC's mode via the sound control panel, you have to install the driver.
However, you can also use the Cosmos_Tweak utility to change modes, and that will work fine without installing a driver.

I also have used the tweak utility but each time I push the connect button it always report a mono mode whatever the sound control panel position is or its previous position was. So I had a tendency of distrusting it.
So one more question about the tweak utility. Does it systematically change the E1DA to mono mode when pushing the connect button? Or does it make the change only when you move the volume ?

Please try using Java EXCL in REW. It's REW's native Wasapi Exclusive mode.

Thanks I'll try later

The sensitivities are the same in Mono or Stereo, with a Bal or Unbal source.
They are the RMS voltage required at the ADC's input for -0.5dBFS output.

That is new information for me thank you. -0.5db is around 5.4%. Making the correction on my measurements I still have around 5% too much. I suppose it is then within the variability of manufacturing. I suppose that they are not calibrated in V. Or should I look for something else ?

 

[Abrise]

When the output impedance of the DAC is say 100R and you measure 1Vrms with no load, what voltage level does the Cosmos see after connecting the DAC ? (assuming 1.7V input range)

When I connect a Voltmeter I of course connect a load. Its high but its a load.

If you use 1Vrms as a calibration level (ADC), you will make a mistake.

Normally no. It should remain the same. The DAC will try to push more current to keep the 1V and some just cannot, that's why while pushing more current some DAC will enter into clipping. It has been reported so. Modern DAC will just keep their 1V properly.

 

[LKA]

So my Topping D10s is not a modern DAC. The open voltage is 1.0025 Vrms, when connected to the Cosmos ADC (stereo, unbalanced, range 1.7) the voltage drops to 0.9604 Vrms. I need a more modern DAC.

Assuming that the output impedance of D10s is 20R, it follows that Cosmos ADC input impedance is 460R in unbalanced mode (range 1.7V)

 

[staticV3]

So my Topping D10s is not a modern DAC. The open voltage is 1.0025 Vrms, when connected to the Cosmos ADC (stereo, unbalanced, range 1.7) the voltage drops to 0.9604 Vrms. I need a more modern DAC.

Assuming that the output impedance of D10s is 20R, it follows that Cosmos ADC input impedance is 460R in unbalanced mode (range 1.7V)

The math checks out:

 

[LKA]

yes, I know, the measurement and the datasheet agree

 

[Abrise]

So my Topping D10s is not a modern DAC. The open voltage is 1.0025 Vrms, when connected to the Cosmos ADC (stereo, unbalanced, range 1.7) the voltage drops to 0.9604 Vrms. I need a more modern DAC.

Assuming that the output impedance of D10s is 20R, it follows that Cosmos ADC input impedance is 460R in unbalanced mode (range 1.7V)

OK I understand what you mean now. Yes your DAC is a very good DAC and apparently it withstands the very low impedance input of the E1DA in its worse case by the way. But I was looking for much higher difference than the -0.4dB that you find and on much higher input impedance also where the effect you are talking will be devided by 5.

 

[LKA]

I was unable to switch to stereo mode with the Win10 default driver. It was always in mono mode. After installing this driver, switching between modes started working.

SXW_setup_WHQL_20210429.rar

drive.google.com

In Ubuntu 22.04, I didn't have to do anything, switching worked.

I use the java exclusive mode without any problems.

IMHO, linux is a better system for audio measurements than windoz, I use it more frequent.