Hello,

I came across the following problem which I would like to solve with your
help. My brand new iRiver iFP899 provides a stereo line-in jack for
connection to any kind of source providing line-in level for direct
encoding. It can also be used as external mic input via settings in the menu
of the player.
I guess the jack input features so-called "plug-in power" which means that a
few volts of bias on the mic input is injected, which can power some small
consumer-type electret mics that don't have their own battery (although most
do have batteries anyway). I measured the input and it provides about 3.15V
(DC unloaded) for bias voltage. Funny enough, the bias voltage does not
dissappear when I switch to "line-in" mode from "external mic" mode.
Now I want to connect my hifi mixer to the device to record old vinyl
records, CDs, whole real-time mixes etc. As soon as I plug the device into
the mixer line-out output the VU meters overflow, i.e. they show full
amplitude. I guess that is due to the "wrong direction" current travelling
INTO but not OUT OF the mixer because of the bias voltage on the wire. What
tricks can I use to couple the device to my mixer so the iRiver line-input
DC bias does not reach the external source and does not affect it?

Many thanks in advance and best regards

Quinn

Quinn asked:

What tricks can I use to couple the
device to my mixer so the iRiver
line-input DC bias does not reach the
external source and does not affect it?

Get a male and female plug and wire a capacitor in series with the "hot"
lead between them. Insert this in between the two devices. I would
suggest about a .1 mFD cap.


---MIKE---
In the White Mountains of New Hampshire
(44=B0 15' N - Elevation 1580')