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E1DA Cosmos ADCiso Review

Rate this ADC:

  • 1. Poor (headless panther)

    Votes: 3 2.1%
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    Votes: 1 0.7%
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    Votes: 126 86.9%

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amirm

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This is a review and detailed measurements of the E1DAC Cosmos ADCiso specialized Analog to Digital Converter (ADC). The grade "B" was kindly purchased by a member and costs US $179.
Cosmost ADCiso Analog to Digital Converter Review.jpg

As you see, you have dual balanced inputs. Back side has two USB-C inputs: one for power and one for computer interface. The former is isolated and hence the "iso" in the name. I powered the unit using a Samsung phone charger I had on hand.

Bottom of the unit has a large set of DIP switches. These set the maximum input voltage as to optimize the dynamic range of the ADC. As shipped, it defaults to 4.5 volt max which is good but input impedance is very low at 1.7 k Ohm. You can go up to 10 volt input but even then, input range only rises to 3.5 k Ohm. As a reference, RME ADI-2 Pro input impedance is 18 k Ohm with higher max input voltage. My Audio Precision default impedance is 200 k Ohm.

Lower input impedance lowers the input noise which I suspect why it is selected to be so low. If the source you are measuring has constant output impedance then the impact is just a reduction in measured voltage. Otherwise, you will modify the source frequency response. If you don't understand what I just wrote, you probably should not try to measure anything with it. :)

Let's measure and compare the performance of ADCiso to that of my Audio Precision APx555 analyzer and a few professional interfaces.

E1DA Cosmos ADCiso Measurements
I started with the default configuration of 4.5v range at 1.7 kohm input impedance:
Cosmost ADCiso Analog to Digital Converter Measurements.png

This is excellent performance. Worst case distortion is at -135 dB which way below threshold of hearing. This would be good for measuring amplifiers with it.

Here is how the SINAD compares to professional audio interfaces:
Best ADC Interface Review 20224.png


Again, keep in mind that input impedance of the ADCiso is much lower so you can't substitute it in all cases.

As a way of reference, here is Audio Precision APx555:
Audio Precision APx555 Loopback Measurements.png


The high performance analyzer turns on a secondary ADC which just measures the main tone and then subtracts it out from the signal. That way, the primary ADC is just measuring the noise/harmonic distortion which is at far too low level of level to cause any non-linearities. As a result, you basically have no distortion in the analyzer as you can see in the FFT.

You can see the impact of range/impedance switching in our dynamic range test:
Cosmost ADCiso Analog to Digital Converter Dynamic Range Measurements.png

So you better know the output level of your source device and reduce the ADCiso's range to just be above it. APx555 analyzer attempts to justify its 100 times higher price with this level of performance:

Audio Precision APx555 Loopback dynamic range Measurements.png

:)

Note again that AP's measurement is with 200K Ohm input impedance with automatic maximum input voltage of 160 volts

Frequency response is quite extended and flat at 192 kHz (some ADCs aren't):
Cosmost ADCiso Analog to Digital Converter frequency response Measurements.png


IMD performance is excellent and is basically noise limited except mid level range:
Cosmost ADCiso Analog to Digital Converter IMD Measurements.png


Edit: forgot to post this:
Cosmost ADCiso Analog to Digital Converter THD+N vs Frequency Measurements.png


The dashed lines are with 4.5 volt range.

Conclusions
The Cosmos ADCiso aims to deliver extremely good performance in specialized application of measurements and not needing high input impedance. It nicely succeeds there and delivers it at such a bargain price. You do need to understand its limitations if you are going to use it for measurements so please don't jump in with both feet without learning about that. :) An amplifier for example can easily blow up its input stage without a scaler to bring its level down (on top of needing a dummy load).

Note also that you need suitable software to go with it. You can get some work done with free software but the pretty graphs above come at high licensing costs from Audio Precision.

I am going to recommend E1DA Cosmos ADCiso.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
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Thanks... But I don't understand what is it! Is it an ADC for digital measurments only or is there any way to use some output for audio usage?
I mean they’re more for inputs.. So digitising vinyls or record audio if the latency isn’t bad.
 
Thanks... But I don't understand what is it! Is it an ADC for digital measurments only or is there any way to use some output for audio usage?
Not your fault. :) It can be used as an ADC. You just have to be mindful of the fact that it puts a heavier load on the source device than a standard audio interface. For many sources feeding it, this should be OK. But not guaranteed.

The low input impedance was a decision made to make the ADC better for audio measurements.

Net, net, it is an ADC/audio interface but with some footnotes.
 
Same question.

Can I plug an analog only mic preamp into this to connect it to my PC to get better conversion than my audio interface?
Most likely you can. You may lose some of the gain of the mic pre if its output impedance is high.
 
The grade "B" was kindly purchased by a member and costs US $179.
Thanks to the member that sent this in and for your testing Amir.

Just a small error in the thread title I thought I'd mention (not that it matters much), it's E1DA Cosmos ADCiso, rather than E1DAC. :)

Specs;
SNR and DR
Grade A: 128-129dB(A)
Grade B: 126-128dB(A)
Measured in MONO mode; SNR/DR in STEREO mode is 3dB lower; Measured at 32/48 AP2700Specifications
Dimensions
104x61x39mm (PCBA: 90x50x29mm)
Weight
157g (PCBA: 34g)
Power
USB-C +5V rail, <250mA current/separated for ADCiso
Input
USB bridge Comtrue CT7601CR(ADCiso CT7601PR with native 768K) Custom FW
XLR L/R (FDA) up to 10Vrms
AUX 2.5mm Jack up to 43Vrms
Output
USB-C, PCM up to 32b/768kHz/ADCiso has that connector isolated with 8pF
Latency
5mS@192k ASIO4ALL REW (Measured as a physical delay/2 from ADC input to the 9038D output)
Frequency Response
0.8Hz-320kHz @ 32b/768kHz -3dB
THD+N and THD
THD+N@[email protected] SR48kHz BW 20-20kHz: 0.00007%
SINAD: >123dB typical for Grade A, 122dB Grade B
THD@[email protected] BW 22-22kHz: <0.00003% (0.3-0.2PPM)
Typical for 32b/48kHz all harmonics level: -135 to -145dB
Crosstalk
< -140dB @ 1kHz / ADCiso
<-153dB if not used inputs are shorted


JSmith
 
Same question.

Can I plug an analog only mic preamp into this to connect it to my PC to get better conversion than my audio interface?
There's not much of a gain to be able to make a mic to actually, work. Here's a teardown of its older brother, to better understand what's inside.

Still, you can anytime use Cosmos ADC with Cosmos APU in front and use recording software's digital volume control to get the proper input volume needed. Still, not having a standard volume control knob might make such a combo valuable only for some pro folks needing to squeeze out the best THD+N out of their audio studios, while most others would prefer a regular studio interface.
 
Hi Amir, I believe this should be moved to the audio interface section of the forum, not DAC. Also the brand should be E1DA not E1DAC
 
Same question.

Can I plug an analog only mic preamp into this to connect it to my PC to get better conversion than my audio interface?
Hi
If your mic preamp has an output impedance low enough, that should work.

Note though that high end analog mic preamps usually have an output level that may reach more than this ADC will accept, even on max 10V range.
(A Neve or a Millennia, as an example, may push up to 28dBu on the output before distortion.
So you'll loose part of their potential dynamic range.)

That may not be the case for lower end mic preamps, but, in that case, the limiting factor is probably not your interface's ADC.
A Topping E2x2 or a higher end interface with mic preamps will probably give you better results than this one, with much more flexibility, for most practical cases.
 
E1DA Cosmos ADCiso Measurements
I started with the default configuration of 4.5v range at 1.7 ohm input impedance:
@amirm
Thanks for measuring this one

For measurements, you'll use it in "mono" mode, by sending the same signal to both inputs.
This mode is switched on by the Windows volume control.
LEDs are then lit in a different color.

How did you measure it ?

Given the difference between channels in your measurements, it's quite possible you measured it in mono mode.
The score should then be the left channel only (which is the average of both inputs, for approx 3dB better noise).

Note that if you split the signal to measure to send it to both ADC inputs, you have an even lower input impedance to load your DAC or measured device !
 
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How did you measure it ?
I measured it by just plugging it in. The thing came with no documentation. :( And my googling didn't get me anywhere either.
 
"MONO/STEREO modes are switchable by the UAC2 volume commands, for example, if your Windows volume slider position is less than 50%(0 to 49%) the device works as 2 channel ADC, if more than 50% it is a MONO ADC with summed Left+Right inputs mapped on the Left channel(Right input is always mapped to the Right channel). In the MONO mode, both channels need to be tied together L+ to R+, L- to R-."

"LEDs on the front panel work as a "Signal" indication - green if the STEREO mode and the input > -30dbfs, or blue in the MONO mode."


I know: it's a bit... geeky

In E1DA's Discord channel, quite some people get confused with that as well.


Note that you don't need to re-measure:
Left channel result is (most probably) mono performance, while right channel gives you the stereo performance.

You may just want to record both values separately in the SINAD chart.
 
Last edited:
Hi
If your mic preamp has an output impedance low enough, that should work.

Note though that high end analog mic preamps usually have an output level that may reach more than this ADC will accept, even on max 10V range.
(A Neve or a Millennia, as an example, may push up to 28dBu on the output before distortion.
So you'll loose part of their potential dynamic range.)

That may not be the case for lower end mic preamps, but, in that case, the limiting factor is probably not your interface's ADC.
A Topping E2x2 or a higher end interface with mic preamps will probably give you better results than this one, with much more flexibility, for most practical cases.
I just had a question about dynamic range on mic preamps. Does bigger output dbu translate into bigger dynamic range? Thanks.
 
@amirm > nice to see this measurement ) Thanks.

I really invite everyone to read this little guide about this Cosmos ADC
How to measure amplifiers with Cosmos ADC

Keep in mind you will need a Low Pass Filter (LPF) to measure properly a Class D amp.
You can also ask @oal about his Self-made Low-pass filter (LPF)

Example of Sylph Audio D100 TPA325X. accurate measurements with Cosmos ADC :


1714108587975.png
 
Amazingly performing little cheap device. If I were only into measuring..
 
I love these gems! $180, gets casually compared to an APx555 analyzer and goes to the top of the chart. Incredible!
 
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