RAT and mods

[Renegadrian]

I'd like to build a RAT soon.
I see some info, Dano mightier mouse and the Ruetz mod.
So I'd like to take those ideas and change them a little.

* switch 1 - on-off-on - Si diodes- none - LEDs
A bit different from Dano idea...diodes switching and the no-diodes option.
How'd it sound with the diodes left off, in that middle position?! Shall I go with only a 2 pos. switch for the 2 different options above?!

* switch 2 (what I'd like to implement)
I understood that the RAT has those 2 RC filters (a cap and a res.) and the Ruetz mod implies cutting off one of them from the signal path, or install a switch to make one or both of these mods switchable for even more versatility.
My question on this one...Is it possible to have a 3 pos. switch to go filter a (47 ohm/2.2uf) - both (stock) - filter b (560 ohm/4.7uf)?
How should I wire a combination like this?!

[Electron Tornado]

I think you will get an increase in volume without the diodes there to clipthe signal. If you get any clipping it will be coming from the op amp.

For the  filter, you can get a 3 position switch where the switch action is On-On-On. Another thing to try is using a linear taper pot to sweep between the filters. The additional resistance from the pot that will result in different frequency response from the filters. But it will also make them variable, which might be interesting.

[reverbie]

I have tried modding both filters....cutting out the 560/4.7uf pair has less of an overall impact than the 47/2.2uf pair....basically the 560/4.7uf mod would be better served with a bass cut switch. Also I've seen guys splice in diodes to different parts of the circuit for distortion variety and also wire in a warp control with the clipping diodes with much effectiveness. Might be better place to implement a switch of some sort. You should really just etch out some of those mini diode boards that were floating around a while ago...there is a DIY board that has the rotary switch mounting right in the middle of the diode board...anyone have a link to that? There are also feedback loop mods out there somewhere that I saw on youtube that looked cool.

[andrew_k]

Dano's FKR offers the on-off-on diode switching you suggest. With no clipping and the LM308 IC, I find it to be a lofi boost with few redeeming attributes. Where the on-off-on clipping comes in handy is if you add clipping options to the op-amp's feedback loop. You can then have clipping near the output, clipping in the loop, neither, or both. Check out Dano's FKR doc's for the details.

Also, the symmetrical Si and LED clipping are the only clipping options I use on my FKR build. I don't think you'll miss leaving out the MOSFET+Ge clipping option.

[Electron Tornado]

I have tried modding both filters....cutting out the 560/4.7uf pair has less of an overall impact than the 47/2.2uf pair....basically the 560/4.7uf mod would be better served with a bass cut switch. Also I've seen guys splice in diodes to different parts of the circuit for distortion variety and also wire in a warp control with the clipping diodes with much effectiveness. Might be better place to implement a switch of some sort. You should really just etch out some of those mini diode boards that were floating around a while ago...there is a DIY board that has the rotary switch mounting right in the middle of the diode board...anyone have a link to that? There are also feedback loop mods out there somewhere that I saw on youtube that looked cool.

I'm working on a pedal in which I want to try various filters in that same position. Looking at the Rat schematic, I've wondered about the reasoning behind having two filters there.

Have you, or anyone else, tried any other filters there, either in the circuit together all the time, or selectable with a switch or a pot?

[Renegadrian]

Thx for the replies...After your posts, I think I'll be using just 2 on-on dpdt, 1 for LEDs/Si diodes and 1 for engage/disengage the 47 ohm/2.2uf RC filter...