Re: Ipod to stereo amplifer: getting volume

In article <475009b0.1246905@xxxxxxxxxxxxxxxxxx>,
NoSpam@xxxxxxxxxxx says...
On Thu, 29 Nov 2007 08:55:27 -0800, Jitt <tser827@xxxxxxxxx> wrote:


My kids had Creative mp3 players that would not produce
sufficient sound volume when connected to "aux" inputs
directly. I made an adapter cable that loaded each headphone
output with a 33 ohm resistor; this gave useable volume.
A later Samsung unit did not have the problem.

OK, I just have to ask: How does loading with a 33 ohm resistor
*increase* the volume? Normally we would expect a load to only
*decrease* volume, since it becomes the bottom leg of a voltage
divider with the output impedance of the source the top leg.

Or is there some sort of automagical sensing in the output circuit,
that increases the level when it sees a low load impedance?
Seems possible, and maybe even logical, so the same connector
can serve as headphone and line out. But I haven't encountered
it before... it this common?

Best regards,


Bob Masta

DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!

I was thinking the current-oriented output was unable to
drive the relatively high impedance input; the 33 ohm load
allowed the output circuit to function, developing enough
signal voltage across the resistor to give useable volume.
.

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