Cosmos APU a notch+LNA $70 to outperform APx555b for $30,000

[1audio]

DiAna has an exceptional visualizing ability and can work with this hardware. The passive notch is any essential start but not enough on its own.

 

[Markw4]

Assuming that's referring to this DiAna: https://www.data-odyssey.nl/Diana.html

 

[1audio]

Yes Do check it out.

 

[IVX]

if anyone is interested in repeating. The inductors are SLF12575T-221M1R3-PF, caps GRM3195C1H473JA05, RESISTORS ARE Viking 0207 200ohm.

 

[GKTAUDIO]

Hello,

I am unable to get REW to recognize my Cosmos using the Comtrue ASIO device driver, only Java, and only as an input device with that driver.

I have also tried ASIO4ALL V2 and FlexASIO - none allow my Cosmos to work with my Windows 10 laptop.

I can get it to work on my Win 11 desktop computer with what I believe are the same drivers, but would prefer to use my laptop for measurements.

Can anyone help me with the proper installation in Win 10 so I can actually use this great DAC so it doesn't just get sold off or sit on a shelf?

Thank you.

 

[IVX]

GKTAUDIO, pls try to install the Comtrue driver, the product page is here https://e1dashz.wixsite.com/index/cosmos-adc

 

[GKTAUDIO]

Thank you, but as I said, I have the driver installed but it doesn't recognize the ADC. I reinstalled it after using the link you provided, but still it doesn't recognize the Cosmos.

 

[IVX]

pls try such settings.

 

[GKTAUDIO]

I have used the setting you provided and it appears to be working. Is it satisfactory to use the JAVA selection?
Thank you for your help!

 

[PMA]

Looks like Java with Wasapi Exclusive?

 

[IVX]

right, that's why EXCL.

 

[tombo56]

Is it satisfactory to use the JAVA selection?

Comparing ASIO and Java, I couldn’t find any advantage in using ASIO drivers so I’ve switched to Java drivers as an only choice. Cosmos ADC is recognized outright on Windows 10, Windows 11 and Linux and works flawlessly at any sampling rate.

 

[GKTAUDIO]

Thank you for those observations.

 

[capslock]

The device is quite simple and inexpensive, strange that's not on the market already. Especially inexpensive(~$70) would be a version without the case as a PCBA which any DIYer can adjust by 4pcs trim-pots(2pcs for the 1kHz Twin-T -30db or -40db, another pair for 10kHz -30db).

Maybe this is a dumb question, but why would you want to adjust to -30 dB vs. -40 dB or any precise attenuation? Wouldn't you want to go for the best achieveable suppression?

 

[IVX]

I found 30db is stable, easy to get with no parts preselection, and enough to get -150db resolution at the same time. You can try to readjust It from 30 to -70db but it will be not always possible without very well caps matching. Also, need to understand that the buffer and diff amp THD aren't zero.

 

[capslock]

Thanks, I understand. But why would one want to adjust to a specific attenuation? Does it make running analysis afterwards easier?

 

[Markw4]

But why would one want to adjust to a specific attenuation?

Usually there is no need for that, say, especially if using something like REW software which can compensate for whatever notch you have.

 

[gentlevoice]

Hi IVX ... hope you are fine where you may be ...

I have a question that I hope you can help with: In relation to the measurements bohrok2610 did in this thread:

https://www.diyaudio.com/community/threads/phase-noise-in-ds-dacs.387862/#post-7063038

Would it be possible to "relatively easily and non-destructively" modify your ADC and (upcoming?) DAC so that they use an external oscillator? Or maybe it is something you are considering implementing for a future version?

Personally, I would be interested in measuring close-in phase noise of DACs and, as I understand bohrok2610 in the above mentioned thread, being able to use the same clock (I would be interested in using one of Andrea Mori's oscillators, e.g. at 22 or 24 MHz, or a lower frequency) for both the ADC and the DAC would allow for seeing the skirts of DAC responses to an even higher degree.

Cheers, Jesper

 

[IVX]

gentlevoice, I think you can mod the existence model quite easily. Take off the original osc NZ2520SDA and mount another one on a small PCB.
However, bohrok2610 thread isn't about the clock source but the clock power rail 1/f noise.

 

[Markw4]

However, bohrok2610 thread isn't about the clock source but the clock power rail 1/f noise.

Its about both. The FFT spectral line noise skirts are a product of both clock close-in phase noise, and of Vref noise. However in the time domain one is timing errors, and the other is amplitude errors. On a FFT, both produce a spray of frequencies very close to the test tone frequency. For small errors of either type they may be considered more or less equally bad. IOW, a sample at the wrong time is roughly as bad as a sample of the wrong amplitude. However, IME they don't necessarily always sound the same perhaps due to differences in the exact frequencies and or their phases (of which phase is not shown in most typical audio FFTs).