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Analog_Fan

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Mar 22, 2022
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PC mixer.jpeg

hi there,
For experimenting i wanna build a PC powered audio mixer and sourcing the 12V power from the ATX psu in from the pc.

What's your thoughs about this schematic?
I have done in the past for CV mixing in the modular synthesizer and worked perfect, but AC coupling was not needed.
 
Powering audio devices from a desktop PC isnt a good idea at all , you'll almost certain have noise issues in the analog signal path .
A small standalone mixer with USB connection to the PC will do exactly what you want .
 
Powering audio devices from a desktop PC isnt a good idea at all , you'll almost certain have noise issues in the analog signal path .
A small standalone mixer with USB connection to the PC will do exactly what you want .

Well Thnx, i was thinking about adding a USB B connector, but i though the ATX psu would do the same job.
Should i opt for the USB B type connector?

USB_B.jpg
 
Check ebay for '

5V TO 12V -12V +12V Mini DC-DC converter board'​

for your experiment.
Agree with Tubetec - noise issues will need to be solved.

R

5V should be enough, splitting them, results in +2.5V/-2.5V witch leaves me about 1V headroom over line audio.
It works in phones, co players, etc.
 
?
USB 5V > tacked on converter board gives you +12 and -12 for your opamps.

The one I use has all the ins/outs in a row such that you can solder in a pin array and have it as a plug in on your pcb.


R
 
CD standard is 2V RMS maximum output, which is just a little more than +2.8V/-2.8V.


You made me scope the output of my pc.
I played a track on my pc on full loudness with the scope on 1V/div and i measured 2 V.p.p.
I have "faders" on the inputs it should work, it doesn't have to be a hi-end thing, but just a thing that allows me to hear audio experiments made by a MCU along the pc audio output.

 
the values where Falstad standard, the actual values of the resistor in the circuit is 10K, i only have 100K(A) dual gang pots.
In which case I would advise you to change all the resistor values to 100K. SInce this is a non-critical application a little extra noise will not be an issue.

Cheers

Ian
 
Powering audio devices from a desktop PC isnt a good idea at all , you'll almost certain have noise issues in the analog signal path .
A small standalone mixer with USB connection to the PC will do exactly what you want .


What if i put a 78L10 voltage regulator on the 12 V (Molex) connector?
Than use 100nF and 100uF capacitors after the voltage reg. to filter the noise from the ATX psu?
Would that work?
 
..10nF is too small for smoothing your virtual-ground reference - better make that at least 10uF..

Well, i saw Don Buchla do it on the Buchla 259 complex wave generator and copied the value from that "ever" since.
But many thnx for the suggestion.
 

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