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

A Neumann 103, that's a very specific use case lol 😀

Even the best measurement mics are at least a order of magnitude higher in distortion.
If it's so tricky to maintain the performance all because of the implementation of phantom power, I personally would either make it as something that can be bypassed, or just as a separate unit.
 
This week got some toys from Cosmos.

IMG_0592.jpeg


IMG_0593.jpeg


IMG_0594.jpeg


Below the results from a loop DAC to ADC test in ARTA.

IMG_0595.jpeg


And in REW

IMG_0596.jpeg


With Calibration

IMG_0597.jpeg


There are little differences between Arta and REW.
Is this the best I can expect?
 
BTW, REW has a wonderful new feature "Crosscorrelation" to compensate for the ADC's noise. Even without APU, only with ADC, I see THD+N -125.7db for 9039S, and DR 130db(A). Your result isn't bad too, -2.6dbfs means that at 0dbfs you'll see the THD+N something around -120db stero, or -122db mono.
PS: I gonna make a donation for the REW right now!
 
Is this the best I can expect?

Hahahaha! I know what you're asking, but look at those results! Even three years ago, imagine getting close to this, especially for the price.

Which reminds me... When will the Cosmos DAC be available? 🙂 Separate balanced and unbalanced outputs with small termination resistors so that you can't have an accident on a lab bench with a short circuit. Maybe, just maybe, USB isolation or just a separate DC power supply input.
 
Oke I used the tweak file. For results see the pictures, only third harmonic was lowered. Second harmonic was already optimal.
Tried also lower clock speed.

Starting point

REW DAC-APU-ADC.jpg


With the tweak app

DAC-APU-ADC with tweak.jpg


With Correction in REW.

DAC-APU-ADC with tweak and corr.jpg


I still do not know what the spikes in the 17k region are.
But this is a goodstart for my future measurements. Thanks IVX.