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E1DA Cosmos ADC

MCH

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And Darko's second favorite device discovered at the Munich High End was...... the Cosmos ADC????

min. 31 aprox



you don't read Darko, MHE and Cosmos ADC in the same sentence every day
 

Music1969

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This looks like a great buffer to use with Commos ADC with it's low input impedance

48kohm input impedance, 0.1 ohm output impedance

by the clever @tomchr here


Does this come in a boxed solution that doesn't need any DIY at all ?
 

LKA

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unclear for me
THD+N < -112 dB 2.0 Vrms
THD+N < -112 dB +27.5 dBu

Noise 20Hz-20kHz Unw 2.1µVrms; -113.5dBV
If gain is 1, noise level is quite high
 

Music1969

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Music1969, well, it looks unacceptable noisy yet -112db@2V.
I have no idea how it is possible to get such a noisy buffer(gain=0db!) with just Ok opamps(not to mention best-in-class opamps)..
It is true, it will limit measurements of many of the great DACs coming out now.

You want a buffer that has lower THD+N than Cosmos ADC.

So we wait for Cosmos Scaler - sigh
 

IVX

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The buffer needs only one opamp with gain=1. Even for 2 opamps to get a balanced in/out, I see no way to get the noise higher than one opamp's noise*2^.5.
The expected noise with low-noise opamps would be more than 10x times less, see the simulation below:

2023-06-06_21-19-00.jpg


PS: I did add some 10ohm resistors to both inputs for further OVP implementation(diodes to power rails or to the active clamp circuit). Also, need to add some 22pF or so caps to GND after these resistors to get a radio range LPF.
 

JensH

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It might be useful to add a resistor on each input to ground to allow use with an AC-coupled source.
 

LKA

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IVX, why is this buffer not included already in the Cosmos ADC itself ?
 

IVX

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1) the buffer with 1.7-10Vrms range requires +/-16Vdc rails, hence, 2-3 times higher USB current draw(a standard USB2 has 500mA limit).
2) how to implement AUX up to 43Vrms with moderate complications?
3) silicon prices are still bloody expensive, for instance, ADA4898-2 I bought for about $10/pcs.
4) The buffer will need some OVP, and this is not always trivial if you decided to keep ADC noise at the world record level.
5) nowadays, DACs have no problem being loaded with 1-2kohm.
 

IVX

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The new Cosmos ADCiso will contain footprints to DIY the input buffers. If someone is smart enough to solder a couple of opamps + resistors and caps(teal colored below), he'll get a perfectly buffered Cosmos ADCiso but lose AUX 43V + some risk to burn that buffer with ESD and so on ;)
2023-06-07_13-52-48.jpg

2023-06-07_13-52-10.jpg
 

JensH

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sure, and AC coupling caps too but that doesn't affect the noise performance of the simulation.
I am sure you are aware of it, but someone less experienced may forget it.
As you correctly point out, designing an input stage with very low noise and protection against high voltages is not trivial.
 

pma

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This device is excellent, but it needs educated, qualified operator. Which is good, excellent parameters at low cost, for dedicated users.
 

darmok

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Is the Cosmos ADC no longer in production or in a parts shortage situation? I tried to order one from HiFiGo, who said they had it in stock, but now they are saying that "the number of E1DA Cosmos ADC is limited" and will not be able to ship it. I see some on AliExpress but I'm not sure if those are for real or not.
 

IVX

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Is the Cosmos ADC no longer in production or in a parts shortage situation? I tried to order one from HiFiGo, who said they had it in stock, but now they are saying that "the number of E1DA Cosmos ADC is limited" and will not be able to ship it. I see some on AliExpress but I'm not sure if those are for real or not.
We are keeping our Aliexpress storage for the last 20pcs Cosmos ADC, and preparing for the production new version Cosmos ADCiso(isolated USB version).
BTW, we decided to produce Cosmos Scaler with the same prod.order, so, if anyone is waiting for that "buffer for Cosmos ADC", you are welcome to suggest me anything regarding the Scaler. Currently, there are 2 ch of instrumentation amp, the composite implemented, with variable gain 0..+26db. The gain is manually controllable by 16 log steps or by the autorange mode. The input impedance 200k/100k balanced/unbalanced, output impedance is 20ohm. 0db gain BW 5Hz..8MHz -3db, high-gain BW 5Hz..400kHz(I'd like to reduce to 50-100kHz to get immunity aginst of DAC's noise-shaper noise).
image.png



2023-06-14_09-12-08.jpg
 

morillon

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if one or two low level impedances such as 100/150 and 470ohm.. input impedance adjustment, could become a phono prepre for somes mc cartridges (
26 db which can sometimes be a sufficient gain with certain mc cartridges)

?
;-)
 
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IVX

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if one or two low level impedances such as 100/150 and 470ohm.. input impedance adjustment, could become a phono prepre for somes mc cartridges (
26 db which can sometimes be a sufficient gain with certain mc cartridges)

?
;-)
no, the gain is too low for MC, but 60db of Cosmos APU is fine.
 

morillon

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I'm not talking about prephono but about prepre for mc cartdrige that we use to raise the gain and adapt the impedance that we use in front of a riaa prephono for cartdrige mm..
the same use as a sut .... but active
often go from 26bd to 32/34db...
60db is often too tight with many cartrige mc
also requires a suitable input impedance
 
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