Goodmorning BEN

22 Dec 02 17:47, Jasen Betts wrote to BEN RITCHEY:

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

 JB> 2W into 8 ohms is  4V (RMS)  (so about 12V  peak to peak)
 JB> so a 11:1 divider would be about right

Yes...if linelevel ws 1Vpp, but line level is roughly closer to 1Vrms...
so a 5 on 1 divider would be more appropriate.

Even if full volume would slightly distort it wouldn't blow up anything.
And believe me...you rather have the signal a bit too high than a bit too low.

OTOH...you could have two red LED's antiparallel between signal and ground
as inputprotectors/clip indicators. No need for it but it looks cool!! :-)

 JB> most line level inputs aren't too fussy about source impedance
 JB> (AFAIK)
 JB> so something like this should do it.

 JB>    input
 JB>        ----[7.5R 2W]---+
 JB>                        |
 JB>        +--[0.75R 1/4W]-+----- output
 JB>        |
 JB>    ----+-------
 JB>   ground

Better not take the impedance of the resistors this low....
There is no need to let them act as a dummyload (or your stereo must have a
tubeamp). It will only cost you more on components (although it definitely
keeps the noise down ;-)

Better to choose the values of the components somewhat higher...let's say a
hundered times higher at least.

Not too high because this will make you lose some High freq. due to cable
(interlink) capacitance....

 JB>  or if you want it variable something use a 1K pot (dual for sterio)
 JB>  and stick a 8.1 ohm resistor in parallel with the input.

Yes that is definitely a good idea...but leave the 8.1 ohm resistor out if
you don't have a tube-amp....for a tube amp the 8 ohm resistor is a MUST to
prevent the output transformer from blowing up.

Since I suspect a regular hybrid module or conventional transistor
end-stage, the 8 ohm resistor will not serve any purpose.

Greetz, Thom


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