# Multi Rat



## jimilee (Jan 8, 2022)

So, I came up with this. Any thoughts?


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## fig (Jan 8, 2022)

Nice clipping array! I'm still working on my breadboard version...I even thought about wiring an opamp selection between LM308 and OP07 (lots of jumpers....it's not pretty)


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## thesmokingman (Jan 8, 2022)

you'll want series resistance on the ruetz mod or you're going to have a bad time when the pot is 0R

remember that those resistors don't just form a second order filter, they also set gain ... you'll end up with something closer to the forbidden setting on the expandora if you keep it as-is which ... maybe you want but probably not


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## jimilee (Jan 8, 2022)

thesmokingman said:


> you'll want series resistance on the ruetz mod or you're going to have a bad time when the pot is 0R
> 
> remember that those resistors don't just form a second order filter, they also set gain ... you'll end up with something closer to the forbidden setting on the expandora if you keep it as-is which ... maybe you want but probably not


Thank you sir, you make a good point.


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## jimilee (Jan 8, 2022)

fig said:


> Nice clipping array! I'm still working on my breadboard version...I even thought about wiring an opamp selection between LM308 and OP07 (lots of jumpers....it's not pretty)


I bet not. Rats nest pretty quickly.


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## JamieJ (Jan 8, 2022)

This is awesome. I might give this a go when you get it verified. That hard clipping selection section looks cool to play around with.


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## jimilee (Jan 8, 2022)

JamieJ said:


> This is awesome. I might give this a go when you get it verified. That hard clipping selection section looks cool to play around with.


Sounds good. I don’t see it being a problem. I’m gonna order some boards and see how it sounds.


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## fig (Jan 8, 2022)

MOFSET+LED is one I have not tried.


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## jimilee (Jan 8, 2022)

fig said:


> MOFSET+LED is one I have not tried.


Read about it on diysb. If it sounds bad, I can always put a GE or something else. Really, we can put any diode anywhere in the selector path.


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## jimilee (Jan 8, 2022)

Ordered some through Elecrow, should be here 8-11 days it said. Normally, I use JLCPCB, but the slowest shipping is almost a month, but it's about half the price. I laid out a Hizumitas and ordered it too.


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## jimilee (Jan 9, 2022)

Not completely symmetrical, but not too bad either.


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## JamieJ (Jan 9, 2022)

Looks awesome @jimilee


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## temol (Jan 9, 2022)

Some of the tracks are very close to each other or to the solder pads. Is it auto-routed board?


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## Bricksnbeatles (Jan 9, 2022)

It looks awesome, but I’d personally do a 1p12t rotary, and add some additional clipping modes, just because excess is fun. Probably some schottky clipping, as well as assymetrical LED clipping, some other weirder option, and also no-clipping.


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## jimilee (Jan 9, 2022)

Bricksnbeatles said:


> It looks awesome, but I’d personally do a 1p12t rotary, and add some additional clipping modes, just because excess is fun. Probably some schottky clipping, as well as assymetrical LED clipping, some other weirder option, and also no-clipping.


I had a helluva time coming up with more than just five. Position 8 is no diode. Then either just the feedback loop or nothing but the opamp can be chosen. The roadkill rat has diodes in the feedback loop. I laid out one of those with hard clipping diode options also. It sounds killer IMHO.


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## Bricksnbeatles (Jan 9, 2022)

jimilee said:


> I had a helluva time coming up with more than just five. Position 8 is no diode. Then either just the feedback loop or nothing but the opamp can be chosen. The roadkill rat has diodes in the feedback loop. I laid out one of those with hard clipping diode options also. It sounds killer IMHO.


Oh, no doubt about it— 8 is more than enough! I just like overdoing things haha 

I’m not typically a rat fan, but I’m very much looking forward to seeing this in action!


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## music6000 (Jan 9, 2022)

fig said:


> MOFSET+LED is one I have not tried.


What about out of spec J201 & LED??????????????


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## jimilee (Jan 9, 2022)

There are more than enough slots to mix and match, you don't gotta follow the BOM, it's DIY!


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## jimilee (Jan 9, 2022)

Bricksnbeatles said:


> Oh, no doubt about it— 8 is more than enough! I just like overdoing things haha
> 
> I’m not typically a rat fan, but I’m very much looking forward to seeing this in action!


Me too, I was looking for one, but nobody makes one. The JHS thing is a multi, but not more than a couple of clipping options.


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## jimilee (Jan 9, 2022)

music6000 said:


> What about out of spec J201 & LED??????????????


LED and a Potato, I think sounds like an idea. Maybe a small Rusett.


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## jimilee (Feb 7, 2022)

It’s alive!!!! It’s very rat like, the fat potentiometer is an interesting change. It sounds good thick and juicy, and anywhere in between, or before I guess. The diodes in the feedback loop is even more crunchier, and the GEs, wow! I think I got every rat covered and maybe a few new ones. I just gotta wait for it to be above 55 outside to paint the damn thing.


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## Feral Feline (Feb 7, 2022)

fig said:


> Nice clipping array! I'm still working on my breadboard version...I even thought about wiring an opamp selection between LM308 and OP07 (lots of jumpers....it's not pretty)


There’s at least one guy I read about having switchable ICs in a Rat-build — upshot was the chip didn't matter, other mods did more to change the sound. 

Still, it’d be fun and useful to build a test-bench chip comparison doodad that you plug into the IC socket of whatever you’re working on for quicker A/B testing than manually swapping ICs while the memory of what the first IC sounded like fades from memory while getting the second IC set up.

Cannibalise an old computer-printer switcher for its multi-decade rotary… something like this:


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## fig (Feb 7, 2022)

Feral Feline said:


> Cannibalise an old computer-printer switcher for its multi-decade rotary… something like this:


The darned thing sounded so good with just a tin-can and some random Ge diodes, I decided to build the breadboarded one and build another on a proto-sled for further experiments. 

A rotary-array you say? Okay! I say


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## jimilee (Feb 7, 2022)

fig said:


> The darned thing sounded so good with just a tin-can and some random Ge diodes, I decided to build the breadboarded one and build another on a proto-sled for further experiments.
> 
> A rotary-array you say? Okay! I say


Well dammit, time to build a super ultra mega rat!


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## JamieJ (Feb 7, 2022)

Glad to hear it’s sounding good @jimilee - thanks to your inspiration I’ve got a PCB on the way with a 2P4T for soft clipping, hard clipping with LED or Si and an option for no clipping.


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## jimilee (Feb 7, 2022)

JamieJ said:


> Glad to hear it’s sounding good @jimilee - thanks to your inspiration I’ve got a PCB on the way with a 2P4T for soft clipping, hard clipping with LED or Si and an option for no clipping.


Nice, the Opamp clipping is really nice.


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## fig (Feb 7, 2022)

jimilee said:


> Nice, the Opamp clipping is really nice.


Haven't gotten there yet....great job sir!


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## jimilee (Feb 7, 2022)

fig said:


> Haven't gotten there yet....great job sir!


Thank you. Thanks to Elecrow, I got 9 more boards if anyone wants one. I did miss a spot, so you gotta run a jumper from the right side of r9 to ground. I’m gonna stick with JLCPCB.


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## princeofyams (Feb 7, 2022)

You are legally obligated to call it a 'Rat King.'


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## jimilee (Feb 7, 2022)

Already ahead of you! I haven't touched up the colors yet, but this is the layout.


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## princeofyams (Feb 7, 2022)

jimilee said:


> Already ahead of you! I haven't touched up the colors yet, but this is the layout.
> View attachment 22709


Hahaha! That's amazing. Exactly as it's meant to be, nice work, brother!


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## music6000 (Feb 8, 2022)

jimilee said:


> Already ahead of you! I haven't touched up the colors yet, but this is the layout.
> View attachment 22709


Here Ya Go! :


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## jimilee (Feb 8, 2022)

music6000 said:


> Here Ya Go! :
> View attachment 22770


Much likes. Very cool.


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## jimilee (Feb 8, 2022)

music6000 said:


> Here Ya Go! :
> View attachment 22770


Is this a mock-up and can you send me the top image file, that’s really cool, I’d like to use it.


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## music6000 (Feb 8, 2022)

jimilee said:


> Is this a mock-up and can you send me the top image file, that’s really cool, I’d like to use it.


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## jimilee (Feb 8, 2022)

music6000 said:


> View attachment 22775View attachment 22776





Awesome, thank you. It's supposed to be decently warm tomorrow, I'm hoping to get some painting done.


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## music6000 (Feb 9, 2022)

jimilee said:


> Awesome, thank you. It's supposed to be decently warm tomorrow, I'm hoping to get some painting done.


Updated Graphic with png picture for Photoshop!


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## music6000 (Feb 9, 2022)

jimilee said:


> Awesome, thank you. It's supposed to be decently warm tomorrow, I'm hoping to get some painting done.


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