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Re: How to lower CD Player output level ?

Posted by Glenn2 on May 2, 2002 at 05:18:40:
You would measure the values in that way yes, but your configuration has the wiper connected to the op amp output not R617.
The circuit would be:
--OP-AMP-----RA------R617----HDAM----
....................................|
....................................|
..................................RB
....................................|
....................................|
.............................GROUND
Don't forget, with the pot turned right up, RA would disappear and RB would be 50k so without R617 you would have the HDAM directly coupled to the op-amp, but yes, once you have the final resistors in place RA would be more than 470 ohms anyway so you could dispense with R617 and this would be handy for mounting RA. If leaving as a pot (as Bobwire did) best leave R617 in.
As for whether it is best to have the divider on the CDP output or op-amp output, Bobwire has his head screwed on so I wouldn't argue. I guess this config keeps the output impedance nice and low as you're not messing with the output of the HDAM, but maybe someone else could say if it would affect S/N ratio.
Glenn.