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.
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:
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:
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:
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:
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:
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):
IMD performance is excellent and is basically noise limited except mid level range:
Edit: forgot to post this:
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.
-----------
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/
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:
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:
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:
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:
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:
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):
IMD performance is excellent and is basically noise limited except mid level range:
Edit: forgot to post this:
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.
-----------
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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