What are you driving with this? If the load is a relatively high impedance
(20k or higher, I see two 1k resistors in series on each output), the
series resistance should have minimal effect.

Do you really need an LPF there? If not, you can save some parts and
possibly drop the resistor values.

One concern, if your load is a low impedance, is what the chip can drive.
It may not be able to source or sink enough current for a low impedance
load.

Finally, be careful about capacitive loads on op amps. The capacity along
with the output resistance will cause a phase delay in the output, which
is then additional phase delay in the feedback, which can make the circuit
unstable.

Good luck!

Harold



> I'm sorry for the barrage of posts. Can you tell I finally got a day
> to start thinking about my project again?
>
> My current project involves some analog signals, which is not my area
> of expertise.
>
> The circuit I'm loosely basing my design on is here:
>
> http://www.cpeproto.com/mixer_sch.pdf
>
> If you take a look at it, you'll see that on the outputs he's got a 1K
> resistor and a .01uF in an RC filter. According to the math I did,
> that results in a low pass filter of just under 16KHz.
>
> I did a bit of prototyping, and that 1K resistor is really impacting
> the audio level that the circuit is capable of putting out. Based on
> more math, if I increase the capacitor to 1uF, then the required
> resistor goes down to under 10 Ohms.
>
> So the question is...what am I trading off for doing this? I'm
> guessing the original author made his choices for a reason, I just
> don't know what it would be.
>
> Thank you!
>
> Josh
> --
> A common mistake that people make when trying to design something
> completely foolproof is to underestimate the ingenuity of complete
> fools.
>         -Douglas Adams
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>


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