After playing around with this for a while I find reducing the gain on the input stage seems to get rid of the harsh noise from a hot input. Not sure if this will work for every circumstance, but it did work for my guitar.
To make up for the reduced output I modified the output buffer. This also made for a better effect in my opinion. I feel the trem sounds better when unity gains falls in the middle of the trem sweep.
Here’s a few notes. Part numbers follow the original schematic from Stompboxology.
R14 was 470K. Make this 309K (or there about). Lowers the input gain
and clears up a lot of nasty distortion that shows up when the input
R16 was 3K3. Just remove this, or replace it with something really
large ~1M. This increases the gain at the output. Which makes up for
the gain lost by the first change and gives it a little extra gain for
a better tremolo effect.
R25 was 25K. Make this 100K. This decreases the lower end of the rate.
I like the slow tremolo sound. I’d almost like to make this a little
larger. But it might require a weird size pot 120K, 150K, 200K etc.
You can fiddle with C15 also, but this tinkers with the fast rate
which I like.
I had an idea to build another with a switchable rate cap for super
fast audio rate modulation and regular low frequency modulation. The
HF modulation might give a weird sort of “ring moddy” tone.