> Any chance of getting the old one archived out there? I didn't look too > terribly hard in the FTP server for it... But it would be nice to be > able to compare and see how the enhanced mic audio and what not are done > as the series 1uF caps from W9AC are still in place...
Brett, On Rev. D of the Main DSP Board, mic coupling cap C28 was increased from 0.1 uF to 1 uF. On the alternate mic path, R24 and R26 were scaled from 1K to 10K while keeping C36/C37 at 1 uF. A 10x scaling increase in series resistance has the same net effect on the low-frequency turnover point as does a 10x increase in series capacitance. Line In was affected the same way with an increase at R18/R20 from 1K to 10K while keeping 1uF of series capacitance. The 10K + 1uF combination is good for keeping circuit Z and low-end audio response reasonable while minimizing SMT parts size and cost. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
