E1DA Cosmos ADCiso Review

[Rja4000]

I just had a question about dynamic range on mic preamps. Does bigger output dbu translate into bigger dynamic range? Thanks.

That's out of topic here.
Short answer is: in general yes, at low gain/high input level.

 

[SuicideSquid]

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.

Thank you! That's exactly the answer I was looking for.

 

[dominikz]

Thanks for the great (as always) review @amirm!

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.

It is perhaps worth noting that with the dip switches set for max input level (i.e. 10V for XLR) the 2,5mm AUX input supports up to 43Vrms input, with 13.6kΩ input impedance. This is useful for power amp measurements (so you can theoretically measure up to ~460Wrms at 4Ω).
Adding an E1DA Scaler makes the ADC even more useful for measurements, IMHO, as it gives you limited auto-ranging, mono-mode support without a special Y cable, and a much higher input impedance.

 

[VintageFlanker]

Thanks @amirm

I had the regular Cosmos ADC Grade B, and recently got a Cosmos ADCiso Grade 0. The ADCiso is always battery powered when running my measurements.

As pointed out by @Rja4000, when used in Mono Mode, I should be quite a more capable performer. I can measure 123dB+ SINAD (5V Out, 4.5Vrms In, Mono Mode for each channel) out of my reference tone generator, the S.M.S.L DO300 :

But the reviewed sample is Grade B, I had to pay twice as much to get a Grade 0. Still, even in Stereo Mode, this mismatch between both channels is kind of weird :

I have not experienced this, with none of my two samples.

I didn't check IMD SMPTE VS Level yet with my new ADCiso, but my former ADC had a bit of hump by its own. But that issue seems to be mostly fixed, according to your review.

Perhaps you should state in the review's title that this is an ADC (I mean, I'm not sure that everybody get this by the product's name alone. )

I measured it by just plugging it in. The thing came with no documentation.

...You don't say...

 

[welwynnick]

Many thanks Amir.
You must be a mind reader. This month I decided to buy a Topping D50 III, Revel F206 and E1DA ADCiso, and you happened to post tests of each of them a few days later.
Stock of ADCiso has been short this year, and perhaps there will be a run on them again.

This is a great review of a product from our own member, @IVX. Thank you, @amirm! Those interested in the Cosmos family of products can find them here. Almost forgot, big discussion over here on the E1DA ADC and other Cosmos line products.

There's another ASR thread here about using it as an audio analyser:

Master thread on building an affordable and high performing audio analyzer utilizing the E1DA Cosmos ADCiso (crowd sourced)

[Admin/Moderator - If there are any changes you would like to see, please let me know.] [Last Updated (mm/dd/yyyy): 2/23/2024] [Iteration of this post: 2] Hi All, If you are a regular ASR member, you will notice that many members here uses the E1DA Cosmos ADCiso as part of a high precision...

www.audiosciencereview.com

Anyone considering the E1DA ADC might also consider the QuantAsylum QA403 Audio Analyzer

QA403 Audio Analyzer

29-Mar-2024: The QA403 is back in stock and orders can be placed, but fulfilling orders may take up to 5-10 days. Elektor and Saelig should have stock next week. 26-Feb-2024: The QA403 is sold out until the end of March. We'll resume orders in the middle middle of March once the delivery date...

quantasylum.com

 

[welwynnick]

Adding an E1DA Scaler makes the ADC even more useful for measurements, IMHO, as it gives you limited auto-ranging, mono-mode support without a special Y cable, and a much higher input impedance.

Thanks. How does the scaler affect the SINAD?

Does anyone know how the E1DA APU improves the SINAD that you can measure?

 

[GXAlan]

I measured it by just plugging it in. The thing came with no documentation. And my googling didn't get me anywhere either.

In Windows, you can set the input volume below or above 50%. Above 50% it’s mono. Below 50% it’s stereo.

 

[Groom]

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.

With the new version, is there a finally a mac software similar to windows, to select the filter curves?

An alternative version with spdif-in would be fantastic...

 

[VintageFlanker]

How does the scaler affect the SINAD?

Since you may get a signal closer to full scale with most DUTs (as Cosmos inputs are fixed), it could affect DR, and as such, SINAD. For instance, there :

WiiM Pro Plus - Review & Measurements (Streamer)

He does not have an external DAC. So I will go with your suggestion. I don't remember the outlets with those all-in-one Focal Bird systems. Kind of like the KLH's of the 00's. Thanks for the feedback! Well, I do have another question for ASR members. Is there a path to play select internet...

www.audiosciencereview.com

Does anyone know how the E1DA APU improves the SINAD that you can measure?

It also does, but you need a proper calibration for it.

 

[IamJF]

E1DA Cosmos ADCiso Measurements
I started with the default configuration of 4.5v range at 1.7 ohm input impedance:

You forgott a "k" there

It seems it's built like a microphone preamp, these have low input impedances. Phantom power would be nice in that case.
In the circuit the over all impedance counts (normally dominated from the low source impedance), low input impedance only helps with high input currents of the preamp/first transistor stage. Not sure if this is really needed here?

AND - the unbalance between the 2 channels is alarming - the rest measures really nice!

 

[KSTR]

the unbalance between the 2 channels is alarming

There is no unbalancing, it is a result from the used setup for the ADC. With its volume control at max the left output channel is the average of left and right input channel and right output channel is the right input channel.
That's where the 3dB better noise values of the left channel comes from, but actually it's the same as the right channel (give or take a fraction of a dB).

 

[KSTR]

An alternative version with spdif-in would be fantastic...

With the latest firmware it provides an SPDIF source signal at an internal pin... you "only" need to make your own little PCB and fit the output circuitry of SPDIF and/or TOSLINK there.

 

[welwynnick]

Since you may get a signal closer to full scale with most DUTs (as Cosmos inputs are fixed), it may affect DR, an as such, SINAD. For instance, there :

WiiM Pro Plus - Review & Measurements (Streamer)

He does not have an external DAC. So I will go with your suggestion. I don't remember the outlets with those all-in-one Focal Bird systems. Kind of like the KLH's of the 00's. Thanks for the feedback! Well, I do have another question for ASR members. Is there a path to play select internet...

www.audiosciencereview.com

Many thanks. So it fills in the gaps between the ADC's input levels, so you're always using the full DR?

Doesn't the scaler also get round the issue of the low input impedance of the ADC (for $129) ?

 

[August]

The unbalanced left and right channels may be caused by the mono mode of the adc being enabled.Volume over 50% on windows will enable mono mode.

 

[daniboun]

I love these gems! $180, gets casually compared to an APx555 analyzer and goes to the top of the chart. Incredible!

$180 + self made LPF filter = $240 if you intend to use it as a multipurpose analyzer

 

[SSS]

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.
View attachment 365913
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 ohm input impedance:
View attachment 365914
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:
View attachment 365921

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:
View attachment 365916

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:
View attachment 365917
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:

View attachment 365918


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):
View attachment 365919

IMD performance is excellent and is basically noise limited except mid level range:
View attachment 365920

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.

-----------
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/

Tried to buy one. Not available. Contacting the developer page eMail address gave no reply. What I saw is that the input impedance is pretty low for some measurements like preamps and specific tube preamps.

 

[staticV3]

Does anyone know how the E1DA APU improves the SINAD that you can measure?

It's a Notch filter. Same concept as the APx555.

At the ADC input you reduce the amplitude of the main tone so that the ADC has an easier time measuring distortion.

You then reverse the notch filter with a digital correction and run your SINAD calculation on the resulting FFT.

For reference, an ADCiso alone maxes out at about 124.5dB SINAD while the APU extends that to about 131dB. No special software is required, just REW.

 

[dominikz]

No special software is required, just REW.

But it should perhaps be noted that Cosmos ADC+REW measurements with an external notch filter are not automated - there is (an additional) learning curve.

 

[welwynnick]

But it should perhaps be noted that Cosmos ADC+REW measurements with an external notch filter are not automated - there is (an additional) learning curve.

Do you mean that the measurements aren't automated WHEN THE NOTCH FILTER IS USED?

 

[welwynnick]

Tried to buy one. Not available. Contacting the developer page eMail address gave no reply. What I saw is that the input impedance is pretty low for some measurements like preamps and specific tube preamps.

Grades 0, A and B are available on the Aliexpress store:

https://www.aliexpress.us/item/1005003391728199.html?pdp_npi=4%40dis%21GBP%21%EF%BF%A1252.11%21%EF%BF%A1252.11%21%21%21306.18%21306.18%21%402103854017141254719864751e7c50%2112000034959488902%21sh%21GB%21913365820%21&spm=a2g0o.store_pc_allItems_or_groupList.new_all_items_2007523643497.1005003391728199&gatewayAdapt=glo2usa

I believe the scaler has a high input impedance, for a few dollars more...