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E1DA Cosmos ADCiso Review

Rate this ADC:

  • 1. Poor (headless panther)

    Votes: 3 2.2%
  • 2. Not terrible (postman panther)

    Votes: 1 0.7%
  • 3. Fine (happy panther)

    Votes: 13 9.5%
  • 4. Great (golfing panther)

    Votes: 120 87.6%

  • Total voters
    137
OP
amirm

amirm

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But how much is the input impedance? How low is low?
Depends on what you want to measure. For accurately measuring the voltage, you would need to have far higher input impedance than this device provides. At 200 Kohm for balanced, the AP is good enough in this regard. 1.7K at 4.5volt on this device would be problematic. But if you don't care about absolute voltage levels, then it becomes that of the loading that it presents to the source device and if that creates distortion that otherwise would not be there if you used a preamp in your system with higher impedance.
 
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amirm

amirm

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Re: russian forums. It is true that what Ivan wrote wasn't very respectful, but reading too much into it is a mistake. Things routinely said over there would be considered rude, toxic and plainly unacceptable on majority of english-speaking forums. People can talk like that to each other for years and consider each other buddies and friends. It is a much much more direct and confrontational culture, and border between banter and insult is not where you assume it is. Keep that in mind if you ever want to google translate something from russian forums and social media. Especially technology related.
I am good at factoring out cross-cultural issues. This is not that. You don't even see Ivan using this defense. Let's look at what he writes:

"Amir who -he sent Cosmos ADC grade B for testing, I myself would never have given him anything for review. It’s just that he’s a completely wild teapot, one word - manager/blogger))

And here, without delving into it, he gave 4V to the ADC (set to 4.5), that is, almost 2 dB without loading it to full scale and gave the result measured by the space of his AR generator - 120db. The ADC was in mono and the right channel came out -117, of course, he averaged it into the table, getting -119dB. That's a deer.."


You think there is a translation error when he calls me "manager/blogger?" You think I am a manager/blogger?

Then there is the technical bit. He claims that I should have tested it at 4.5 volts input even though vast majority of DACs I test stop at 4.0 volts and a few go up to 4.2. Is he imagining that you can force the DAC you are measuring to output more voltage as to make this ADC happier? Or that it would be fair to test his ADC at 4.5 volts while testing all others at 4 volts?

On that "mono" thing, why in the bloody hell does he not provide that simple documentation in the box? This is not a $5 item. Instead of spending money on that ugly wooden box that it came in, print a sheet or two of paper explaining odd and highly unique aspects of a product like this.

And what the hell he expects me to do when left and right channels produce different results? I average them because that is the only fair thing I can do as many devices generate differing responses in each channel.

He goes on:

"Well, I don’t feel sorry for the 1.5 dB lost by him, just measure an underfed ADC, just because “4V input is Amir’s measurement standard,” how’s that? What if they sent him an ADC switched to 10V, or 1.7V? It’s like writing reviews of light bulbs, ONLY 24V, 12 volt ones burn out in the first seconds, the output is unreliable, and 230V ones don’t light up at all - faulty? )) He is 100.00% a non-technical person and has no reason to be offended by this."

I am 100% non-technical person? You think that is a cultural thing among Russians?

And he thinks a difference of 1.5 dB would have made an impact on my review which was universally positive? The offense comes from someone lacking so much in common sense and social aptitude to write insulting comments about me here and there over that, when the argument itself is faulty.

Earlier he said that he was all positive on Archimago. Yet this is what he writes about him:

"Take Archimago, this is definitely a technician, moreover, corrosive, but also careful. He wrote to me, having received the 9039S for testing, saying yes, without load everything is the same, THD+N is -126dB, cool, but on the 16th it’s not even close to -124dB, can you explain?"

That sure as heck doesn't sound like a praise to me even if the "corrosive" translation is wrong.

"Yes, it’s me who kicks Amir every time)) He’s an illiterate little bast, and now he writes, they say, I gave this Ivan the best recommendations, but contrary to common sense, he dunks me in calla lilies every time."

You think this can be explained by cultural differences? Or translation? I gave him an incredibly positive review while holding back everything I know about him and this is what he posts?

No. This is a person who has no common sense. He is constantly insulting both here and elsewhere. About me and others. Here is the manual of his again:

"Anyone has "am I boomer?" psychological complex, who feels the LED blinking is too much 1960th style, please request in our discord channel for the Boomer_free Firmware with no LED flashing + how2reflash instructions - you are welcome "

If you want him to improve at all, please, please don't make excuses for him. He will continue to be the way he is. He needs to start respecting other people's knowledge. He needs to be more professional. He needs to be more cordial. He needs to know his place and level of expertise. And he won't if you try to explain away conduct that even when on topic is completely improper. The racist remarks are just on top of that.
 

pma

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Low input impedance of the E1DA Cosmos ADC is a non-issue only when measuring power amps and headphone amps. For all and any link level preamp measurements it both reduced output voltage and increases high order crossover distortion. It is the fact. The device is not universal, it needs a high impedance, low noise, low distortion buffer.
 

AudioJester

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@amirm , digging deep in the mud only attracts the trolls into the forum.

Are you actually going to call out Ivan on his behaviour?
Or do you think Iam a troll and calling out Ivans's behaviour is digging in the mud?

@amirm - you asked for opinions before. I say ban him and move on, Iam sure you have better things to do.
He has his own discord for technical discussions on his products, does not need to happen on ASR.
 

restorer-john

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"he’s a completely wild teapot"

Yeah Amir, you're such a wild teapot...

1714348255125.png
 

undeakyetonde

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I am good at factoring out cross-cultural issues. This is not that. You don't even see Ivan using this defense. Let's look at what he writes:

Hello Mr Amir, thanks for taking time to write a thorough reply

I think auto-translating what is written there and trying to view it through lens of ASR conduct standards is a bit misguided.

I would like to assure you that it reads different in context of a russian-speaking tech forum, kind of like over-exaggerated banter. Locker room macho talk, if you wish. Overly toxic and obnoxious. You yourself quoted a couple of examples. But, even if you take the exaggeration into account, the disrespect is still very much there. I too would be upset if somebody said these things about me behind my back. You are pretty unhappy about this and, understandably, don't want to see Ivan in this community (ASR). But I think there is room for dialogue between you, and reconciliation. In my experience, a good thing is just to meet up, to have a zoom/teams call (or whatever), and talk. A lot of the internet toxicity and pretense vanishes when you actually see the person :) Maybe you and Ivan could consider such a meeting.

I really hope Ivan can learn something from this conflict, and I also hope the whole situation is not too disheartening for you.

Re: automatic translations - they are literal and that's enough for the most part, missing some slang words and sometimes not matching the tone.
But this one I can't leave behind
Earlier he said that he was all positive on Archimago. Yet this is what he writes about him:

"Take Archimago, this is definitely a technician, moreover, corrosive, but also careful. He wrote to me, having received the 9039S for testing, saying yes, without load everything is the same, THD+N is -126dB, cool, but on the 16th it’s not even close to -124dB, can you explain?"

That sure as heck doesn't sound like a praise to me even if the "corrosive" translation is wrong.
The word is въедливый. Literal meaning is corrosive, but in this context it is a metaphor for something like being thorough, meticulous, willing to go deep, etc. Very much a praise. In the whole paragraph I can easily read the implication that he was impressed and satisfied by Archimago's technical knowledge.

(edited to shorten up the response)
 
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Watire

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But how much is the input impedance? How low is low?
Common cassette tape decks provided between 30K to 100K ohms of input impedance, some reel to reel had 50K ohms. Integrated amplifiers had 25-50 K ohms impedance for line inputs when they were popular. The higher setting of Cosmos is 13,6K ohms and it starts at 640 ohms.
 

Roland301

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I am curious, can AP perform "high performance sine generator" -> "ADC analyzer" loopback to make it more "apples to apples" with this device that doesn't have notch filter built in?
 

KSTR

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I am curious, can AP perform "high performance sine generator" -> "ADC analyzer" loopback to make it more "apples to apples" with this device that doesn't have notch filter built in?
That's a very good question... and it could well be the results are slightly worse as the ADCs they use (AKM AK5394A, discontinued) are spec'd a bit worse than the ES9822pro.
 

capslock

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That's a very good question... and it could well be the results are slightly worse as the ADCs they use (AKM AK5394A, discontinued) are spec'd a bit worse than the ES9822pro.
I am not even sure I understand the question :)

The picture Amir showed was "high performance analog sine generator" --> "ADC analyzer in high performance mode". So Roland suggests to do the same thing with the regular ADC analyzer - correct?

Do we understand how the sine generator achieves - 155 dB HD3 and <= 160 dB for everything else?

Do we understand how the ADC high performance mode works? I have a blurry picture from Amir's explanation, maybe I got it wrong: one ADC measures the signal, the fundamental is extracted digitally, synthetically generated by a DAC, and a diff amp subtracts this artificial fundamental from the original signal and the difference signal is fed to another ADC? So this is kind of a digital notch. Correct?

As for the AK5394A, I remember seeing that it is incredibly good for HD, and that it doesn't have the low noise shaping corner of most modern ADCs. Whether it is as good as the ES9822pro on very low harmonics, I'd like to see. I have some hope that it will be better on IMD.
 

KSTR

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The picture Amir showed was "high performance analog sine generator" --> "ADC analyzer in high performance mode". So Roland suggests to do the same thing with the regular ADC analyzer - correct?
Just without any trickery, i.e. no notch. Straight ADC performace as is.
 

KSTR

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So this is kind of a digital notch. Correct?
No, notch is analog.
The second ADC measures the pre-notch signal and that is blended in (bandpassed to keep its distortion out) to visually show the total signal.
 

pma

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Input impedance impact

As an example, I measured Marantz SA7001 in CD mode, direct to Cosmos ADC vs. the same with inserted buffer (100kohm/50ohm 1:1).
With this player, the main difference is in voltage drop (1.963V/1.573V). THD+N (SINAD) improved of some 2dB with the buffer. H2 is lower of 6dB with the buffer, quite considerable difference. H4 is improved of 3dB. Both due to lighter load of the SA7001 output stage with the buffer.

Marantz_Cosmos_direct40.png Marantz_Cosmos_buffer40.png
 

pma

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The other point that needs to be understood is an input impedance in the Cosmos mono mode when measuring a component with single-ended RCA output.

E1DA_input_impedance.png


Though the impedance specified is 1kohm for 2.7V input range, it is valid only in case of balanced input of 1 channel in the stereo mode (R1 + R2 = 1kohm). In the mono mode, L and R inputs go parallel, reducing input balanced impedance to 500 ohm, but this goes again to half, 250 ohm, if we measure any single ended output device, because -In branch (R2, R4) is effectively shorted and we have R1//R3 as a result, thus 250 ohm only. Thus the voltage difference in my previous post. So, be very careful, comparing Cosmos ADC and APxxx distortion test results and level measurements when link level sources have been measured.
------------------------------
I know that Ivan @IVX declares a bit higher value of input impedance in the single-ended mode. I was curious and made measurements of the input impedance. In the single ended mode, 1 channel, I got 673 ohm for the left and 605.5 ohm for the right channel. In the single ended mono mode it makes 318.75 ohm, which is a bit more than 250 ohm estimated above. By simulating with OPA1632, I get 666 ohm in the single ended 1 channel mode and 333 ohm in the mono mode. This is pretty close to the measured values. I am curious if @IVX has anything to add ;).


SE mode:
1714413306768.png
 
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amirm

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Just without any trickery, i.e. no notch. Straight ADC performace as is.
Audio Precision is not selling an ADC. It is selling a measurement system with all of its features built-in. Members like to generate results that are comparable to mine. Since I use high performance sine analyzer, then they need to know if they can get there with this box as is.
 
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