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Circuitbenders Forum => Circuitbending discussion => Effects Units => Topic started by: selfpreservation on November 16, 2011, 10:22:03 AM

Title: stacking switched op amps
Post by: selfpreservation on November 16, 2011, 10:22:03 AM

hi i have a ratt pedal and i would like to install 2 op amps and switch betwen  them

can  i simply piggy back them on top of each other and bent the v+ and v-legs of both up and fit a dual pole switch between them to switch the power rails between the chips when  i want to use either chip

Title: Re: stacking switched op amps
Post by: Circuitbenders on November 16, 2011, 12:29:38 PM

Thats an interesting question. I'm not that familiar with the RAT circuit but i think what i'd try would be to keep both opamps powered and rather than switching the power, just switch either the the input or output, or both, from one chip to the other.

Effectively you'd be isolating each opamp from the signal chain as you switch between them. I suspect that switching the power would cause a speaker popping amount of switching noise.

Have a look at the section headed 'switching and stacking' here http://www.beavisaudio.com/projects/ScreamerLab/ (http://www.beavisaudio.com/projects/ScreamerLab/) .What they seem to be doing is just stacking the opamps and then switching the outputs from one chip to the other.

Let me know how you get on with this.

Title: Re: stacking switched op amps
Post by: selfpreservation on November 16, 2011, 01:25:24 PM

ah just switch the i/o that makes a lot more sense  :-[ ill give it a go

Title: Re: stacking switched op amps
Post by: tbone on November 16, 2011, 07:15:50 PM

If you're modding a RAT pedal have you tried the ruetz mod?
Very simple and very useful!

Title: Re: stacking switched op amps
Post by: selfpreservation on November 18, 2011, 08:21:28 AM

Quote from: tbone on November 16, 2011, 07:15:50 PM

If you're modding a RAT pedal have you tried the ruetz mod?
Very simple and very useful!

I've seen that I'll probably do that too and make it on off on switchable open on  one side and with a pot on the other
I'll probably do the other germanium and MOSFET mods too and make them all switchable I haven't started yet I'm waiting on opamps on a slow boat from china  ,it sounds ok I don't know what it's like on guitars but it's a bit wooly on synths I find so I'm hoping the mods are gonna make it rock but I like my mods to be able to return to factory mode so best of both worlds
I have an Arion overdrive pedal from the eighties OD1 I think it is and it sounds absolutely awesome whould have thought a cheap pedal could sound so cool if you can get one you should especially if you got a TB