byoc wrote:
There is a low pass filter. Several of them. It should sound like an analog delay even though it is digital. So I'm not sure if what you are experiencing is normal and you just don't like it, or if there is actually something wrong.
You can try swapping the PT2399 chips around. Sometimes that helps.
If it is rolling off too much of your high frequency, my first guess would be that you have a component value or two mixed up in the low pass filter section. I didn't notice anything out of place in your pics, but I also can't verify the capacitor values, and some of the resistors are hiding behind other components. So double check component values. Especially look for 100k resistors in place of 10k resistors. Sometimes it's hard to tell the orange and red bands apart.
I just tried swapping the chips and the same. It sounds like there is a LPF at around 200hz. Next step to spend the time to double checking each of the resistors. Thanks!!!