开云体育

Thanks for your reply, yes at the time I write this letter, I also found, that the big elco capacitor Vcc filter is mandatory. I also experiment that one 1000uF is needed. My AF amp is LM386, gain was 200 alias 46dB, the preamp was simulated around 40dB if correct.
My amp still not enough level, except use 2 preamp.

But fortunately I found 60dB preamp after long search in google.? See techlib.com

Thanks
INDRA