On Tue, Feb 5, 2013 at 4:07 PM, Dwayne Reid wrote: > The only reason that the series 1k resistor is impacting your output > level is because you are using a load with too low impedance. I'm > guessing that you are probably trying to drive headphones directly. Yep! Though I've pretty much decided that isn't the correct choice (see bel= ow). > If so, there is a couple of things that you can try. > > First, eliminate the low-pass filter. You don't need it if you are > feeding headphones. I would still have some value of series resistor > but you should be able to start with 22R and go from there. Interesting, I will have to try that. > Second, if the chip doesn't have enough current to drive the > headphones to the desired level, you will need to add a small power > amplifier. You *will* need the LPF if you are driving a power amp > from that chip, just to ensure that ultrasonic noise components don't > cause problems in the amp chip. I have decided that an outboard headphone amp is just a good idea. I've done a bit of research, and the chip I'm looking at has an input impedance of ~14.4K typical. I had grabbed a small headphone amp that I already have to do some experimenting with, but wasn't impressed at the results. I just had a look, its input impedance is 600 Ohms. I'll play a bit more with component values and see what happens. At the moment I'm getting quite a bit of noise from the chip. I'm trying to figure out if it's creeping in due to the breadboard I'm using, or do to crosstalk inside the chip itself. If so, I might have to look for something a bit more direct to get rid of the noise. Thanks! Josh --=20 A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .