[MLUG] Re: I am famous! Audio question.

["Christian M. Cepel" <EMAIL:PROTECTED>]

Since this this topic is dealing with people knowing what they are doing 
with audio, I thought I'd pose a question that's bothering me.

I pulled a nice sony portable stereo apart last night and tried to 
solder two RCA jack leads to the same place on the circuit board that 
the tape 'read' head wires are soldered to.

I'm tired of using a 'car tape adapter' when I want to hook a metronome 
to it for the bagpipe band (it's gotta be LOUD), or when I want to amp 
my mp3 player.

I anticipated that line level for the tape read head would be much lower 
than line level out of my standard 'headphone' devices, and that I'd 
need to turn those sources down to not send too hot a signal which would 
be distorted by the amp circuit.

What I did NOT anticipate was that the audio would be horrible, with 
tremendous distortion (even though it was turned so as to be barely 
audible), and nasty full-spectrum noise.

I had rather hoped to add Aux inputs in this way to my other portable 
stereo equipment as well, but this is quite a bump in the road.

My question is this... What is the difference between the AC signal 
coming from the read head and the AC signal coming from the headphone 
jacks of my equipment?  My first guess is impedance, and that the 
distortion and noise are reflections and such, but I've no real 
knowledge to pursue this guess.  I've been able to find NOTHING online 
about the particulars for both standard headphone level signals and 
magnetic tape read heads.  Does anyone know.

A second cause just occurred to me... that perhaps I would need to add a 
diode between the board and the read head to prevent the input signal 
from entering the 'read head' circuit.

Anybody have any idea how to make this work?

Many thanks for any help.

Mike Miller wrote:
> We wouldn't want you to miss out on Mark Rages' 15 minutes of fame:
>
>
> On Wed, 26 Oct 2005, Mark Rages wrote:
>
> > They put my project on hackaday.com:
> >
> > http://www.hackaday.com/entry/1234000037064924
> >
> > But they got my name wrong.  So much for my 15 minutes o' fame.  It's 
> > fixed now.
>
>
>
> You should be famous for your google map hack.  That was awesome!
>
> Mike
>
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--
  //Christian

Christian Marcus Cepel            | And the wrens have returned &
EMAIL:PROTECTED icq:12384980  | are nesting; In the hollow of
371 Crown Point, Columbia, MO     | that oak where his heart once
65203-2202 573.999.2370           | had been; And he lifts up his
Computer Support Specialist, Sr.  | arms in a blessing; For being
University of Missouri - Columbia | born again.    --Rich Mullins

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