Gerald, you wrote,
>I am curious how the signal is being routed with the different jacks
>on audio recorders and players. The mic jack of a recorder will
>send the signal to some sort of an amplifier I suppose.
Right, it's a specialized type of amplifier called a mike preamp.
>If you plug
>into the line-in jack would the signal be routed differently?
Always. Usually the line-in signal is substiuted for the output of
the mike preamp. With a mike input, the output of the mike preamp
goes to the volume control. With a line input, the input signal goes
directly to the volume control.
Some cheap equipment just uses a pad to lower the level of a line
level signal and puts it through the mike preamp. Pros hate that,
every stage of electronics adds something (noise, distortion) that
you don't want.
>What
>levels of sound would the respective jacks handle?
We talk about electrical signal levels, not sound levels. Sound
levels happen in air, before the microphone.
A mike input is a few millivolts, a few thousandths of Volt, AC. A
line input is around one Volt. The name "line" comes from telephone
line, in radio. A radio station would have to deal with mikes in the
studio, and signals on telephone lines from the network or remote
crews.
>Will the
>headphone jack have a level of signal that would compare with line-
>out?
Headphone output levels are similar to line levels and the phones out
can be used as a line out in a pinch. But the headphone output is
designed to drive a low-impedance load, phones are typically 40 ohms.
A line output is designed to drive medium to high impedance loads,
600 ohms and above.
>Are they routed the same?
No, the headphone output will have a little power amplifier to drive
the phones, a few milliwatts.
>Speaker jacks have probably been
>amplified to a stronger level.
That's right, speaker outputs are intended to drive very low
impedance loads, like 8 ohms. That takes a lot of current, and their
power output capability is measured in tens or hundreds of watts.
-Dan Dugan
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