monsieur yumels
Member
Hello!
After polishing and rinsing with isopropyl then grounding points of the metallic enclosure to avoid issues with ground loops I managed to do some more tests, now with balanced input into one channel using one of those Behringer kabeltester ct200, hence the square wave
I installed a trim poti instead of the 27k resistor before the audio VCA circuitry as Script suggested. And I am confused!
The two xlr inputs (+ and -) are 20mV ACrms and 140mv ACrms giving an output at debalancing stage of 120mVac rms.
With a 27k value before VCA circuitry, the output at pint 7 of NE5532 at audio output stage is 70mV AC rms
With 15 k value the same output goes to 120mVac rms.
Was not the purpose of chaging the 15k value to 27k to provide unity gain between input and output? What am i missing?
P.S- I have around 1mV between signal ground reference and earthing. Is this potentially going to cause problems?
Thanks for your comments!
After polishing and rinsing with isopropyl then grounding points of the metallic enclosure to avoid issues with ground loops I managed to do some more tests, now with balanced input into one channel using one of those Behringer kabeltester ct200, hence the square wave
I installed a trim poti instead of the 27k resistor before the audio VCA circuitry as Script suggested. And I am confused!
The two xlr inputs (+ and -) are 20mV ACrms and 140mv ACrms giving an output at debalancing stage of 120mVac rms.
With a 27k value before VCA circuitry, the output at pint 7 of NE5532 at audio output stage is 70mV AC rms
With 15 k value the same output goes to 120mVac rms.
Was not the purpose of chaging the 15k value to 27k to provide unity gain between input and output? What am i missing?
P.S- I have around 1mV between signal ground reference and earthing. Is this potentially going to cause problems?
Thanks for your comments!
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