io micpre #4

ioaudio · Nov 15, 2005

finally finished...
circuit is close to micpre1, but with added feedback control and without the bypassing cap on the cathode of the ef 86.
some minor value changes, schematic will follow soon.
still have to do the labeling, suggestions welcome.

Flatpicker · Nov 15, 2005

Sweet! :thumb:

northsiderap · Nov 15, 2005

Looking at that thing just stoned me.

Send some waves through it and lay it on us via MP3.

Is that an old reel-to-reel box?

Viitalahde · Nov 16, 2005

Very sweet looking box. Like all of yours! :thumb:

ioaudio · Nov 16, 2005

thanks for the kind words. yes, its a reel-to-reel box, i used the psu
transformer and the housing. still have to find a solution for the labeling...

toffifee · Nov 16, 2005

Ui! :thumb:

ioaudio · Nov 16, 2005

edit: sw1 adds much more than 6dB...

psu:
unregulated ht, 270 vac secondary goes to
4x1n007---470µ---10k---470µ---10k---100µ----ecc81---22k---100µ---100k--ef86
the 100k is already in the schematic above.

heaters go
6,3 vac ---4x1n007----6300µ----1R-----6300µ-----1R------4700µ---heaters

phantom power is taken from bo hansen.

io micpre #4

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