iPod Video (5.5) recording with MicroMemo

[MikeyP]

I've been testing out RockBox 3.6 recording using a Video iPod (5.5g) and an XtremeMac micromemo.

Line In:

Recording with the micromemo set to line in, and a line level source seems ok, gain controls and the volume control work, and recording quality is good.  I'm using the line input in RockBox.

Microphone In:

Recording with the micromemo set to line in doesn't seem to work correctly.  Although I get a recording, the volume is very low, and the recording gain adjustment doesn't seem to make any difference.  The recording is noisy, but that just seems to be poor S/N ratio, I don't think it's interference of any kind. I have tried microphone recording with the both the line and mic inputs in Rockbox, with no apparent difference.

The record meters seem to work correctly in all cases, but the signal is definitely lower when using the micromemo 'mic' setting.

Accessory power is turned on ; this is needed to properly bias the electret microphone, and is probably needed for other functions in the micromemo.

I'm still testing, but in the meantime, does anyone else have experience with recording on the micromemo ?

update:

I did some more mic testing, using a constant volume (loud) source, and a constant mic distance.

I recorded 6 tests, with the recording gain at 3db, 15db, and 32.2db, using both the mic and line recording inputs.  The six recordings are all audible, but have low volume. I can't notice any difference between them on playback. 

For reference, I tried the same recording scenario with the original iPod firmware, and the recording is heavily distorted (clipped ?).

This seems to imply the ipod firmware knows the micromemo is in 'mic' mode, and somehow compensates.

[soap]

Thanks for the excellent series of tests!

Do you have wiki access yet?  It would be great if you could add your findings to the IpodAccessories wiki page!

[MikeyP]

I updated IpodAccessories, there was a prior result in the retest table, that I left untouched.