Line-level input on PPCs.

Iain Campbell (iain@dcs.gla.ac.uk)
Sat, 29 Oct 1994 14:29:34 -0400


The sound input socket on a PPC machine definitely expects a "line-level" input.

Using a normal 3.5mm stereo plug, you can give your PPC a line-level input
and it'll be happy. eg from a radio, CD player, video player, etc

A normal mike (or one of the old Macintosh mikes), on it's own, will NOT work.

A device, like some tape recorders, that accepts a normal mike and then
offers a line output, is necessary to use a normal microphone.

The Apple "PlainTalk" microphone is special in that it has a preamplifier
inside the case. That amplifier gets its power via the extra long 3.5mm
jack plug that it has. That extra long bit reaches inside the PPC case and
picks up power from a special contact.

The power contact being deeper in the socket prevents power from being sent
out to audio devices via a normal length 3.5mm plug. The power would
interfere with the incoming signal and possibly damage the external audio
equipment.

The bummer is that you can't make yourself an extension lead for your
PlainTalk mike. (ie those extra long plugs and sockets are not available).

Cheers,

Iain.

____________________________________________________________________________
Iain Campbell email: iain@dcs.gla.ac.uk
Computing Science talk: iain@mull.dcs.gla.ac.uk
University of Glasgow tel: +44 141 339 8855 ext.6292
Glasgow G12 8QQ fax: +44 141 330 4913
SCOTLAND web: http://www.dcs.gla.ac.uk/~iain
____________________________________________________________________________