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In the Forum: Analog Playback
In the Thread: 7788 tube mic pre design
Post Subject: More WhinePosted by hagtech on: 1/13/2008
I guess I need to try out some more samples. Only have a few here. And only one has a long time constant 5kHz ring. Heaters are 6.2Vdc with 20mVrms sinewave ripple at 120Hz. Fed from schottky - L - C. Other side of heater is grounded. Operating points are low, with only 80V on plate, at maybe 13mA. Sort of in a bind here if the 7788 doesn't work. I'm re-using a low voltage B+ supply (only +105V) from another project. With a choke on plate or CCS (line level output) I still get enough headroom.
Maybe I could use some step-up tranny. Although they would be dangerously near the power supply chokes. It's a small box.
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