proco rat mods

[deadbeatriot]

more specifically, does anyone know how big a difference the original lm308 ic makes? or how dramatic the reutz rat mod is?

[bubstance]

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[cloudscapes]

switching the diode pair to different types of diodes is a mroe meaningful mod, IMO. you can swap em out for leds too, and neither of them have to be the same type.

changing the input cap for darker/brighter sound.

I AB'd an original PROCO (m308) with my diy that uses a common 071 and honestly the difference wasn't mind-blowing. the diode mod in the original made more of a change.

[deadbeatriot]

thanks fellas. i want to sorta make it more overdrivey and less harsh, but maybe not permanently? i was thinking about doing a sort of combo opamp switch/ switchable reutz deal. unfortunately, i don't know anything about different opamps and wouldn't really know where to start. i might do the socket thing, but then i wouldn't know what to do with the chips that don't make the cut...

[dune2k]

Use them in your next project.
The Ruetz mod is really nice, changing the clipping diodes not so, kinda depends on what you put in. LEDs clip a little later but sound somewhat like normal silicon diodes, especially on higher gain settings.
Different OpAmps sound different! Although there's not a big difference you can clearely hear a difference between say a 741 (BJT Input) or an 071 (FET Input).
You could easily make the Rutze mod switchable too, you just have to lift one side of the 47R resistor out of the circuit (preferably the one connected to the opamp).

[Gilmourish]

a DIY thread without Scruffie? what is going on?!

[Scruffie]

a DIY thread without Scruffie? what is going on?!

Here I am haha, nah I figured these guys had covered most of the good stuff so I passed it up, plus i've been out drinkin' beers in the sun

Although... removing the Diodes entirely should make it less harsh and more overdrivey as then only the OpAmp is doing the clipping, be prepared for a large volume boost though.

Plus this link - http://www.beavisaudio.com/Projects/FKR ... rMouse.gif

[dune2k]

a DIY thread without Scruffie? what is going on?!

Here I am haha, nah I figured these guys had covered most of the good stuff so I passed it up, plus i've been out drinkin' beers in the sun

Although... removing the Diodes entirely should make it less harsh and more overdrivey as then only the OpAmp is doing the clipping, be prepared for a large volume boost though.

Plus this link - http://www.beavisaudio.com/Projects/FKR ... rMouse.gif

To me it sounds a lot harsher with the diodes removed...sounds nice in a way though.

[Scruffie]

a DIY thread without Scruffie? what is going on?!

Here I am haha, nah I figured these guys had covered most of the good stuff so I passed it up, plus i've been out drinkin' beers in the sun

Although... removing the Diodes entirely should make it less harsh and more overdrivey as then only the OpAmp is doing the clipping, be prepared for a large volume boost though.

Plus this link - http://www.beavisaudio.com/Projects/FKR ... rMouse.gif

To me it sounds a lot harsher with the diodes removed...sounds nice in a way though.

I always thought that too, but I figured it was just my ears as most people disagreed that this would happen... and I see the point, I think it could be the increase in volume that leads to a perception in gain and rolling it back may make it smoother, not hard to try really though and put back if it isn't to taste, that's what modding's all about!

[nbabmf]

I'm building a Rat right now with some variations on the Beavis FKR theme. I'll post the rundown when I'm done.

[deadbeatriot]

hmm. when i'm taking the resistor out for the reutz mod, can i just pull the thing out, or just take out one side, or what? i'm not too experienced with these things...

[Scruffie]

hmm. when i'm taking the resistor out for the reutz mod, can i just pull the thing out, or just take out one side, or what? i'm not too experienced with these things...

Take it out, if you connect to one side and connect to that what you'll have is that the pot wont go lower than the stock value, which you can do if you want.

Just wire it as shown here without the resistor in http://www.beavisaudio.com/Projects/FKR ... rMouse.gif

[dune2k]

Although... removing the Diodes entirely should make it less harsh and more overdrivey as then only the OpAmp is doing the clipping, be prepared for a large volume boost though.

Plus this link - http://www.beavisaudio.com/Projects/FKR ... rMouse.gif

To me it sounds a lot harsher with the diodes removed...sounds nice in a way though.

I always thought that too, but I figured it was just my ears as most people disagreed that this would happen... and I see the point, I think it could be the increase in volume that leads to a perception in gain and rolling it back may make it smoother, not hard to try really though and put back if it isn't to taste, that's what modding's all about!

Since I play bass my amp(s) are clean. So you could definitely tell the difference. Clipping OpAmps are usually a lot harsher than clipping diodes.
Maybe there's also a difference because most guitarists use tube amps which compress the signal...dunno. Anyway, it's a nice & easy mod to try out.

Re: Ruetz Mod: You can just clip one side of and solder it to a switch (SPST will do) and solder the other side to the board. Now you have it switchable. Or as scruffie said you can install a "lube"-control just like in the FKR.

Re: MOSFET Clippers: Don't try to get the IRF510s (If you got a cheap soure they are fine though.). They are hard to get and BS170s or 2n7000s are just fine too.