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@@ -581,3 +581,52 @@ A68: The old MOD/AJZ was not entirely deleted from the disk. It is still Power it up and ...voila... Rockbox is there! (Thanks to Olivier Rafidison for this info) + +Q69: What kind of mic can I connect to my AJBR? +A69: There are several types of microphones. + Dynamic: The one that's available from archos is a dynamic one. + Their output level is high enough so that they don't need an + amplifier (that's the reason why the archos mic is of + this type - it's cheap). + - cheap + - no good sound quality of cheap dynamic mics (good enough for + speech) + - no amplifier needed + Backplate Condenser: These are the professional mics. They need phantom + power (48V) for charging the condenser. + They also need an amplifier, because their output level is low. + - good sound quality + - need phantom power (48V) + - need amplifier + - expensive + Electret Condenser: These capsules are cheap and result in a good recording + quality. They don't need phantom power voltage. They need power + for the FET (field effect transistor) that's inside. If you have + such a mic with a battery in it, it is mostly because of the FET + power, not because of an amplification circuit inside the mic. + These mics are in all the consumer products like mobile phones, + PC headsets and so on. + - cheap (2 EUR for a capsule) + - good sound quality + - need amplifier + - need power for the FET (1,5 - 15V) + recommendation for do-it-yourselfers: Use electret condenser mic capsules, + solder an amplifier for them which both amplifies the output level + and feeds the power needed for the FET to the capsule. + The one on http://www.geocities.com/ferocious_1999/md/micpreamp2.html + was soldered and tested by Uwe Freese, and it works. + There are some others available from www.elv.de and other sellers. + recommendation for others: Buy some mic + preamp combination which can be + plugged into a line in of any amplifier. Maybe such a commercially + available combination needs a power supply and doesn't work with + batteries. Some are very expensive. (If you know a cheap solution + with an electret condenser mic + preamp, please tell us!) + what does not work: Don't use an amplifier thing that can be simply connected + between some mic cable. Maybe it sounds as if it could work, but + I doesn't. If the piece of (expensive) electronic doesn't have a + power source and your mic doen't either, it does not work! + A PC sound card or md player has usually a power output (same pin + where the sound goes through, dc value) for feeding the FET of + an electret condenser capsule (see above) (and this power could + also used to feed a mic amplifier), but the archos hasn't + (it's a line in and no mic in!).
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