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A generator (Ri 200 Ohm, 1 kHz) is connected to ADCiso(Left) or ADCiso(Right) via XLR cable. The ADCiso is in Mono Mode. Measurements are made with REW (OS Ubuntu), voltage values are now normalised. Fact is that I recently entered that world of measuring devices, and that's how I got to read your blog. I'm into older vintage devices, you know these old gears that some audiophiles praise more than any new garbage cheap Chinese stuff :-) I wanted to test that myself, and it's amusing to measure 40 years old unserviced devices. Each ADC unit is individually calibrated at a particular level -.5dbfs, and 1kHz frequency. For the best precision of measurements, you also need to keep the input level close to that level. THD across the 0-30dbfs range will be within -120db=1PPM it is not bad but the best is -.5db and most of the samples have there .2PPM. The same regarding the frequency, Cosmos ADC calibrated at 1kHz because it is a standard THD+N test in the audio industry. If you need to measure 10kHz THD better to re-calibrate the ADC with a reference 10kHz sine source first(see above E1DA Cosmos Tweak app) or enjoy 1-1.5PPM of THD. And then, the RME is doing everything perfectly well. And, for most cases, at least as well as the E1DA ADC. Sometimes better. Ideally, multi-device support in REW with WASAPI and/or ASIO natively would be fantastic. I must say that despite the age of WaveSpectra, it's quite impressive how well it handles the hodgepodge of audio driver variants in Windows!
One other useful feature you'll notice is the availability of +48V phantom power for condenser microphone input. There's a warning icon to make sure it's turned off when a line level device is plugged in as the voltage may cause damage.As further warning, there's an orange LED inside the 3.5mm phono input that lights up with phantom power engaged. Make sure to wait for it to fade (about 10-15 seconds) to indicate the voltage has been discharged before plugging in something like a DAC. Yes, it's nice to be able to use the ASIO drivers. With the latest REW, I have been able to use the Cosmos ADC with ASIO as well which is convenient without going the route of ASIO4All or FlexASIO (which still work when I need to use them since Cosmos ADC ASIO is input-only). The third one is a very specialized lens, but gives you results impossible to achieve with the others.A high level specialist may spend some time building a set of test scripts (that's what Amir did, I think), and then a set of less specialized technicians may run the script for QA 24/7, with 100% reproducibility (within a tolerance), in different facilities accross the world. As you can see by comparing the 2 measurements above (the second, with 122dB SINAD, being done with the E1DA ADC), this may limit the output level of the DAC. This is usually done by taking into account the width of the FFT window that is used to compute the levels for each frequency. While I've labelled this article an "EARLY LOOK" since I'm using a pre-production unit, I hope the discussions here provide more than enough information to understand how this works and will get you well on your way with using the device. Customers are to bear the consequences and fees incurred, if the parcel was undelivered due to any of the following situation:
Accidents, abuse, misuse, improper installation, problems with electrical power, acts of third parties. Shorting the two grounds together doesn't seem to measure any different from an open circuit (not pictured). Perhaps this changes when connected to an actual input with actual current (not tested). From that perspective the Cosmos ADC is not an ideal choice for this use-case, as you need an additional box to make it work well. Adding the second may bring you significant additional money, if you're into studio or wedding photography. I have to apologize for my non-native English, and non-literary style. I just want shortly and not too boring to describe what I know about that ADC.
That's my retail Topping D90SE DAC at 4V (not even the higher 5V setting, or approaching the Cosmos ADC's XLR 10V upper limit), -1.9dBFS level (not even ideal -0.5dBFS), no 1kHz analogue notch filter for more precise examination of the harmonic residual (ie. no APU), captured unweighted comparing "stereo" and "mono" modes. In stereo mode, this is already showing THD+N of better than -119dB! In mono mode, both channels have THD+N better than -121dB, minimum "skirting" only below -140dB, harmonic distortion peaks less than -130dB. If you're wondering about the E1DA name, as explained by Ivan, it comes from the pronunciation of "Ivan" as sounding like "E1" in Russian as opposed to the Americanized "Eye-Ven". "DA" as in "dah" ("да", "yes") - so it means "Ivan Yes".] Compared to the typical Audio Precision graphs you see online (like ASR) which often measures at 44.1kHz, I like going the "hi-res" route and will usually show my FFTs based on a 96kHz signal. I'll usually show near infra/ultrasound on the FFT as well (down to 15Hz and up to 30kHz) just in case folks have massive subs and even super-tweeters ;-).
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