Specifications:

 
Device purpose: Ultra-low THD+N variable gain buffer for Cosmos ADC
 
Materials: Sandblasted/black anodized aluminum/laser mark/OPA1612+OPA1656 composite,Viking resistors,Murata, Samsung C0G caps, Taiwanese connectors/relays
 
Dimensions: PCBA 90x50x29mm104x61x39mm
 
Weight: PCBA 40g / 160g

 
Power: USB-C +5V rail, <500mA current

 
Input:
2 channels balanced 200/100kOhm bal/unbal
3.5mm jack up to 20/10Vrms bal/unbal
If only the left input is plugged, the signal is routed to the right channel as well, to implement MONO mode for Cosmos ADC. Cosmos APU's short cables are suitable for Scaler as well. 


Output: 

2 channels balanced 20/10hm bal/unbal
3.5mm jack up to 20/10Vrms bal/unbal
Cosmos APU's short cables are suitable for Scaler as well.
 

Variable gain table:   
in db 0, 7, 10.7, 13.38, 15.788, 17.38, 18.673, 19.844, 21.08, 21.98, 22.764, 23.513, 24.336, 24.965, 25.527, 26.078
16 positions controllable by the knob, in the "Auto" position Scaler works like a ultrafast autoranger(100mS) with the left channel target 4.5Vrms.
The right channel output voltage is ignored. 20Hz-20kHz is the valid frequency range for autoranger.
 

Frequency Response: 
.2Hz-570kHz @ 26db gain +.5/-3db, .2Hz-7..11MHz @ 0db gain 10MHz area depends on a cable(Scaler's output is stable up to 7m of mic cable) capacitance
 
Residual Noise:   

250nVrms(A) @ 26db gain typical 
 

Distortions:

The only indirect measurement method is available at such a low level due to a huge loop gain OPA1612+OPA1656 composite(170db@1kHz/130db@10kHz)
Something like 100x times less than Cosmos ADC or H3 -175db@1kHz at 0db gain
 

Crosstalk:

L->R -133db, R->L -158db@1kHz unused input is shorted @0db gain 

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