Boss SD-1 to Tubescreamer

[tman]

Hey I have just been looking at the schematics on the web of the tubescreamer. The one difference I have noticed is that from the clipping diodes and the inverting input on the opamp is that the .047 cap and 4K7 resistor goes through a 100K resistor back into the inverting input also it is tied to 4.5v

However on the Tubescreamer this just goes to ground what is the better option ?

[cd]

Hey I have just been looking at the schematics on the web of the tubescreamer. The one difference I have noticed is that from the clipping diodes and the inverting input on the opamp is that the .047 cap and 4K7 resistor goes through a 100K resistor back into the inverting input also it is tied to 4.5v

However on the Tubescreamer this just goes to ground what is the better option ?

On the TS-9 there should be a 10k resistor.  Either way it should make no difference sonically.

[tman]

What do you think will help my sd-1 sound a bit fatter it sounds quite thin sounding.

[cd]

What do you think will help my sd-1 sound a bit fatter it sounds quite thin sounding.

1) read "Technology of the Tube Screamer" at www.geofex.com, it has everything you need to know there, or
2) change the input cap to .1uf from .022uf
3) change cap in feedback loop to .1uf from .047uf (the one connected to the 4.7k resistor)

Experiment with different cap values, once you increase the bass you'll probably find the distortion is muddy.  That's just how the circuit is.