Latest project USB/MIC/LINE preamp/mixer.

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Latest project USB/MIC/LINE preamp/mixer.

Postby nigelwright7557 on Sat Oct 08, 2016 11:42 pm

Nearly completed my latest project.
I use a USB DAC module to get stereo USB.
The other input can be from a MIC, guitar or line.
It uses two 12au7 valves.
Image
nigelwright7557
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Re: Latest project USB/MIC/LINE preamp/mixer.

Postby nigelwright7557 on Thu Oct 20, 2016 9:05 pm

It uses two transformers back to back.
The first transformer drops 240VAC to 12VAC for the heaters.
The 12VAC goes into a 18VAC winding and is transformed up to 160VAC.
The 160VAC is rectified to give the valves B+.
The mic input uses one triode to amplify the signal by about 51 times.
The USB input is mixed with output of mic channel into another triode.
So USB gets amplified 15 times and mic gets amplified 225 times.
nigelwright7557
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Posts: 22
Joined: Sat Jan 14, 2012 11:04 pm


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