path: root/docs
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authorUwe Freese <>2002-12-10 23:54:22 +0000
committerUwe Freese <>2002-12-10 23:54:22 +0000
commite229ca4d111e1308dc8ccd6320c0c9b8ed252226 (patch)
treede14b38f067f3953b87805e4f9fff6d0e4120849 /docs
parentc9743e2c18b2c39cd8de9a3db909e129df4d904d (diff)
added q+a about mics. Feel free to correct my bad english or other things.
git-svn-id: svn:// a1c6a512-1295-4272-9138-f99709370657
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diff --git a/docs/FAQ b/docs/FAQ
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--- a/docs/FAQ
+++ b/docs/FAQ
@@ -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
+ was soldered and tested by Uwe Freese, and it works.
+ There are some others available from 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!). \ No newline at end of file