A good morning to you BEN

On 21 Dec 02 17:05 you wrote something about *I/F*...

 BR> I have a Stereo Audio feed for 2 Watts {at} 8 Ohms (per channel) that I
 BR> need to convert to "Line" level (I'm assuming this is around 1 Vac
 BR> Peak-to-Peak at a much higher impedance) in order to pass the signal
 BR> through an Equalizer, then back thru a secondary Amplifier (probably
 BR> 5-10 Watts per channel, not built yet). Can this be done with a simple
 BR> Voltage Divider like dual Pots and would the pot(s) need to be
 BR> Audio-taper?

I assume that you are talking about a transistor or chip amplifier in the
Stereo Audio.
This is good because you don't have to connect a load to it.
2W{at}8ohm is 4Vrms....you can hook it up directly to your EQ input provided
that you don't turn the volume further up than halfway.

If you want to be sure you can make a voltage divider...
Keep in mind that the inputimpedance of the EQ is 50kOhm
The Stereo Audio has no output impedance...well it is less than 1 ohm anyway.

You don't have to do any impedance matching...only lower the voltage.

If you want to use a minimal number of parts...a single 100kOhm
trimpotmeter per channel will do the trick.. :-)

 BR> Are there any industry standard Audio Amp ICs that deliver approx.
 BR> 10W/RMS per channel I should use for the last stage? I have a couple
 BR> of National Stereo Amps (Lm4755) rated at 11W/channel with low
 BR> noise/distortion specs, I think.

Yes..lots of them...check out the TDA line from Philips.

 BR> I dismantled a very expensive TV to develop the Line-level outputs
 BR> but
 BR> could only work out speaker taps (no schematic :( they go for over
 BR> $50) and cannot risk/afford to cause any damage by playing around .
 BR> My old TV had Audio/Line-out taps that sounded incredible through the
 BR> Equalizer. :)

If you make speaker taps from a TV-set keep in mind that you need
audiotransformers to electrically isolate the line out from the
TV-circuits.

The voltages inside a TV set are lethal...therefor galvanic isolation is a must.

The other reason for galvanic isolation is to avoid a "hum" in
your system due to groundloops. (e.g.: antennabox -> TV -> stereo
-> radiotuner -> antennabox)

Good luck! :-)

Greetingzetcetera, Thom


... Het meeste wat ik inklop gebeurt zonder na te denken....[RM 1996]
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