El Gato TS - Design Question

[karbomusic]

Should I/can I remove the components circled in blue since I'm not using any BJTs? Or any other components that are not needed or for that matter. Leaving them is fine since I've already built two of these on vero, they work perfectly, and love them so I don't want the sound to change. I'm working on a PCB so any type noob review would probably be good about right now if anyone cares to look. I'm obviously not an EE and basically tweaked/designed different TS type bits and pieces and put them together. Just looking for a sanity check before I go further. The tone/clipping IC is a TLC2272 FYI but I didn't seem to have that part in my library.



One of the existing vero builds:

[Keppy]

Yes, in theory you can remove all those plus R4, R6, R18, R19, R20, and R21. The output of each opamp stage will be biased properly for the next stage, and none of those RC combinations appear to have any filtering function in the audible range.

R5 is actually pulling down the bias voltage of your gain stage, by about 9%. I doubt this has any audible effect, but it's actually working against you.

R18 effectively doesn't do anything, since it's in parallel with the much lower resistance of the volume pot. Same with R4, as it's in parallel with R6.

Everything else is just decoupling stages and re-biasing, which the opamps don't really need.

One potential issue: Sometimes voltage offsets at the output of opamps are large enough to cause misbiasing down the line. That's only happened to me with multiple high gain stages, though, so you should be good. You might put a meter on the input and output of your gain stage when set to max gain, though, just to make sure the offset isn't anything terrible.

Also, it appears to me that IC3 isn't really needed. With the components you're removing, it's just adding opamp stages directly to the outputs of other opamp stages.

You could also place the blend pot directly on the opamp outputs and use a single output cap, though this puts you at risk for a crackly blend pot if the opamps have slightly different DC output levels.

In theory, none of this changes the sound at all.

[petemoore]

 Leaving them in there is fine, and 'love the sound' pretty much requires a solid 'no answer.
Changing the value can be easy by paralleling 'stuff', leave resistor or capacitor lead above to hook 'piggyback' parts to, or series /insert/ by standing a part up, soldering both ends, cut the long lead [epoxy standing resistor / / to create connect-insert points, helps glue or reinforce to keep them in position.
 Cut a testclip lead// in half, and /insert/ 1 big pot there, use same with small value pot if needed etc., stuff the test-pots threads into cardboard or tighten to a panel to keep them still. makes it easy to drop/adjust value of resistors, allowing to start with large, soldered in value, taper with pot, put a fixed resistor [close to the pots measured value] where the pot was.
 I did this to voice and set gain etc. on a number of boards I built. I like to add series cap to input because it's very easy, effective and can be bypassed with a SPST.

[karbomusic]

Thanks guys. I basically replaced the original in/out buffers with op amps, then turned the input buffer into a splitter and the output buffer into a blender to service the clean boost running parallel. I'd like to keep those buffer sections but will probably bypass the other extra parts in one of my existing builds just to be sure. If that works out, I'll remove them from the schematic since it is verified of sorts.

[Keppy]

That's a great plan. Like Pete says, if you like the sound there's no reason to change it, except that fewer parts usually makes the layout easier. Good luck!