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E1DA Cosmos ADC

IVX

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Well, finally I got working Cosmos ADC with internal DSP and RIAA EQ implemented for all Fs from 44.1 to 384. A pair of Cosmos APU was used as a dual-mono phono preamp +34db gain with no analog RIAA, which was applied in Cosmos ADC digitally. The video is a comparison of LP vs CD sound, recorded this way.
The formal specs of such combo:
THD+N@5mV-40ohm(AP output) -81db
2022-04-30_11-44-28.jpg

About the real SNR i.e. MM cartridge AT3600L connected to Cosmos APU with 1.2m RCA cable, stylus on the air, the turntable is On and the platter is spinning, the record is normalized to 0dbfs, the SNR for that conditions is 85db(A).
2022-04-30_13-25-22.jpg
looks like 91db(A) but my very loud DJ LP has peaks up to -6dc, hence, 91-6=85db(A).
FFT has some spurs at 15 and 17kHz, they are floating and sometimes completely disappear. I guess this is an electro-car charger in the garage under my apartment.

 

AllanDavidson

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100%! If 20+ years musicians are happy with such an archaic ADC like CS5381(Lynx hilo) why do they need something else?

Most guitar recordings have all the signal being processed/toned in the analog chain before the ADC (usually a mic in front of a tube amp).

I'm doing it all digital, recording the passive guitars straight to the ADC and shaping the tone on the computer, so I need the most Signal-to-Noise ratio that I can get.

I just need to know at what point the hardware is beyond my needs.

Thank you
 

dominikz

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Most guitar recordings have all the signal being processed/toned in the analog chain before the ADC (usually a mic in front of a tube amp).

I'm doing it all digital, recording the passive guitars straight to the ADC and shaping the tone on the computer, so I need the most Signal-to-Noise ratio that I can get.

I just need to know at what point the hardware is beyond my needs.

Thank you
To record guitars with passive pickups well (i.e. high and complex output impedance) you will need an interface with a very high impedance input - this is commonly marked as 'Instrument' or 'HiZ' inputs on professional audio interfaces.
Alternatively you could use a DI box to interface a high-impedance passive pickup to a low-impedance ADC input (such as the ones on Cosmos ADC).

Connecting a passive guitar pickup directly to the Cosmos ADC (i.e. without a DI box in between) will likely result in significant low-passing of the guitar signal, which will be an audible degradation of the signal - regardless of otherwise perfect AD conversion.
This would not happen with a pro audio interface with a HiZ input.
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.

As far as pure audio performance specs are concerned, electric guitar is a very band-passed and relatively low-dynamic range instrument so most ADCs will be able to capture it cleanly - the Cosmos ADC is definitely an overkill for this; though I do appreciate the viewpoint of "better safe than sorry" :)

In summary almost any solid pro audio interface with a HiZ input will be OK to directly record electric guitar into - though I'd suggest interfaces with good SW support and low-latency drivers. Thus far my favorite manufacturer is RME, due to amazing SW support, good audio performance and rock-solid drivers.

BTW I measured audio performance of a lot of pro guitar gear, and I can tell you that in many cases you can be happy when SINAD reaches 60dB - no where close to the stellar 120dB of the Cosmos ADC. Still such gear is used on stages and studios around the world and no one is complaining. :)
 

AllanDavidson

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BTW I measured audio performance of a lot of pro guitar gear, and I can tell you that in many cases you can be happy when SINAD reaches 60dB - no where close to the stellar 120dB of the Cosmos ADC. Still such gear is used on stages and studios around the world and no one is complaining. :)

Ah yes, the world of Guitar, where the experts have lost half their hearing at this point.
 

audiofun

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Cosmos ADC can get a surprising upgrade 50pcs independent biquads for all supported sampling frequencies.
i.e. 25 universal 2nd order stereo filter cells. 25 parametric EQ for example, or RIAA+20Hz_SUBSONIC+23 parametrics and so on.
yeah the es9822's Audio Signal Processors are super, super powerful.
Wondering why they are not included in their recent DAC products.
 

CedarX

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Cosmos ADC can get a surprising upgrade 50pcs independent biquads for all supported sampling frequencies.
i.e. 25 universal 2nd order stereo filter cells. 25 parametric EQ for example, or RIAA+20Hz_SUBSONIC+23 parametrics and so on.
I still don’t get the benefits of a DSP on an ADC… There are plenty of options on the digital side —whether it’s dedicated DSP or PC software—so what scenario ESS was targeting when they decided to include DSP features in their ES9822/42 ADC?
And yes, a DAC with integrated DSP appears a lot more useful (e.g. E1DA PowerDac). Why isn’t it more common? Chip design constraint?
 

staticV3

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On-device DSP can be useful for realtime applications, like EQing a microphone for voice calls
 
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CedarX

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On-device DSP can ve useful for realtime applications, like EQing a microphone for voice calls
Good point, I didn’t think about that use case. Any actual device using ES9822/42 you know about?
 

pos

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the preliminary specs of Cosmos APU are ready, please take a look and suggest any add/changes/questions?
So hyped to see it now has an integrated phantom power!

Do not turn On that power without a mic connected, that may damage the device tied to the APU's preamp input! Please wait for at least 10s after the phantom power is Off, to safely plug/unplug anything to the Preamp input.
Is there a risk for the mic or APU if the mic is plug/unplug while the phantom power is on?


Regarding the bandwidth, it is specified as "10Hz-1MHz+ -3db@60db gain, 10Hz-5MHz+ -3db@34db gain"
What about the actual audio range (20-20k, or maybe 10-40k) ?
 

IVX

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pos, the problem is that device trying to be(but not pretend!) phono-preamp at the same time ;) Phono-preamps have to keep standard input impedance 47kOhm and 100pF, so the LNA IC has a very high cut frequency and the resulting BW is wide as well.
Regarding mics, I believe they are designed to be powered by 48+/-4V 6800ohm and have to be safe.
 

IVX

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BTW, I prepared the plot about the 48V power noise:
LNA_48V_noise.PNG

The gain of Cosmos APU preamp is +60db(1000x times), hence the scale units are nVrms(A). After the APU unit turns On, you can see 5s of settling,
from 6s the input noise reaches 130nV, about 9s 48V power was turned On, and after 1s reached 142nS. Hence, APU's phantom power adds just 12nV to the preamp noise, that's a nearly ideal result as I think ;)
The test was performed with a shorted preamp's inputs(In+ to In-) and biased to the GND by 2x6.8kOhm resistor as a dummy condenser mic.
PS: and the spectrum 20Hz-130kHz of the same test, units need to divide by 1000 as well, so uV becomes nV. This is a good illustration to killing the myth that SMPS is always dirty ;) Cosmos APU contains no linear voltage regulators at all, only SMPS with Fswitching > 1MHz.
LNA_48V_noise_FFT.PNG
 
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IVX

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L7 made some Cosmos APU tests.
 

Hemi-Demon

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and if someone did not understand, APU + almost any ADC(probably your laptop audio does) outperforms AP SYS2 or APx555 if APU + a decent ADC ;) DR, SNR, THD, or THD+N @1k or 10k.

What is the difference between Bundle 1, 2, 3 and 4?
 
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