First a background. I wanted to mic my actors for my film using a lav on each actor and some portable recorder. Some scenes had 5-6 people talking. I first started with iriver ifp recorder with the Giant Squid mics - about 35 bucks per setup. This gave me pre-amp noise as the iriver uses cheap pre-amps. It was recorded as 160kpbs mp3 mono 44.1khz sampling. Then I tried a bunch of used Sony Hi-MD recorders, about 50-75 each. These default to AGC, and I had to buy a MZ-RH1 (M200 actually) in order to transfer the recording using USB2.0 (the older Hi-MDs come with USB1.1). The pre-amps on the older NetMd and MD were crap. Now I have the Tascam DR-05, which fixes all the problems related to pre-amps and gives 96khz sampling. However, it is still too big to carry in a pocket.

I found that the biggest problem for human conversational voice is not sampling (44.1khz vs 48khz) or compression (PCM vs 160kbps mono mp3) but pre-amp noise. Resampling can be done easily via command-line using soX.

I also found the form factor of the iriver ifp series to be most convenient for micing actors.

So I looked around for circuits for a simple battery powered electret mono pre-amp for a iriver ifp. BTW the iriver was found to have very low distortion using the line-in setting. http://bartus.org/akustyk/ifp-899/index.html

I found these DIY battery powered mic pre-amp kits.

http://www.canakit.com/electret-microphone-pre-amp-kit-ck495-uk495.html - 11.95/-

http://www.quasarelectronics.com/preamps-mixers.htm#Mono-Preamplifiers-General-Purpose ~ 10/- each

http://www.vakits.com/product_info.php?cPath=43&products_id=260

Has anyone used these, any comments ?? BTW I am looking for something to be powered from a 9V or a AA battery, a portable device.