# Muroidea (ProCo Rat)



## MichaelW (Jul 19, 2022)

As hard as it may be to believe, I've never even played through a Rat let alone ever owned one. 

I know zilch about the ProCo Rat even though I remember seeing ads for them in Guitar Player Magazine when I was a kid.

But @thewintersoldier told me that I was missing a vital and major food group in dirt sounds, and since he's a healthcare professional I figured I'd better listen to him.

I actually got 2 Rat boards, when I was ordering my MBP compressor boards I decided on a whim to throw in the Runt board on my order without realizing it was a 1590A project. After mulling over whether I wanted to try to build a top mounted jack version on a 1590A I decided to build the Muroidea first. 

I definitely get why people love Rats. I don't know how close mine sounds to the ProCo variants but it sounds pretty awesome!
Super snarly and doubly snarly with the bridge P90 on my "90Caster" tele build. Yet it cleans up nice too, backing off on the volume knob or backing off the gain knob gives some nice mid-gain overdrive sounds. That's probably where I will mostly have mine, with the gain knob around 10 o'clock. 

I made a couple of substitutions. I couldn't find an LM308 anywhere, so subbed an OP07. I watched a couple of video's comparing the ProCo LM308 vs OP07 variants and any difference is pretty subtle. 

I also subbed an MMBFJ201 for the output buffer. I did not have a 2N5458 and my big pile of 2N5457's are all out of spec......sigh......

A bit of the usual "negotiation" with the electrolytic caps to fit this build into a 1590B. Glad to add this to my big pile of dirt.....pedals









P.S. I'm still a bit confused about the whole Star rating for the build section. Am I rating the project itself? My build performance? How the pedal performs?
Whatever....I'm giving it 5 Stars so @PedalPCB can earn his quarterly bonus.


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## spi (Jul 19, 2022)

MichaelW said:


> my big pile of 2N5457's are all out of spec


I've used an out of spec 2n5457 in a Rat and it worked fine.  It's a buffer here, and the requirements are more forgiving than other applications (hence you can use a 2n5458 or a j201, which are both "out of spec" from a 2n5457 in different directions).  Pop in one of your out spec ones--if it works you can save a good j201 for another project.


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## Dan0h (Jul 19, 2022)

Nice work! Your shrink wrapped Cap legs are a making me all tingly inside... 

And I agree, the Rat in my Parentheses build is amazing and hasn't left my board since I built it. Recently I have discovered that with a few tweaks of the knobs it can do pretty much all the sounds of many different Fuzz and dirt pedals saving a lot of space on the board and ridding all the duplicates. Chris is a huge Rat supporter and I can see why, the thing is just a do all be all beast. Enjoy your Rat adventures, they sound really epic with octaves. Just saying.


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## swelchy (Jul 20, 2022)

I'll send you a legit LM308.. I have a few in my stash that are the real deal so you can at least compare them.. I've built with both op07 and the 308 and I cant really tell the difference myself... but there is still always that mojo thing about certain parts when it comes to pedal building.


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## Dan0h (Jul 20, 2022)

Nice one @swelchy it may be unicorn magic but I noticed a difference when I swapped out my op with a legit 308. The way it distorts is different through the entire gain range. On mine it was a game changer. But I’ve had other pedals where the mojo part made no difference. Might be a combination of things.


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## jimilee (Jul 20, 2022)

OPO7 sounds good to me, cheaper too.


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## Harry Klippton (Jul 20, 2022)

If mojo parts excite you, or you think it sounds better, rock on. Whatever inspires you


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## MichaelW (Jul 21, 2022)

Thanks @swelchy! I do have a second Rat board to build. I might just stick that in a 1590B instead of 1590A.

Did my care package make it to you?


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## szukalski (Jul 21, 2022)

Even though I had a rat clone (Mooer Black Secret), the Parentheses opened my love. It's one of those pedals where you ask why you ever took it off the board.


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## szukalski (Jul 21, 2022)

thewintersoldier said:


> I sold it because the boost was useless IMO and worked with David on making this board a reality. He agreed it was a good idea.
> 
> 
> 
> ...


That's awesome! The boost on my Parentheses Mini is redundant. I was toying with the idea of modding the footswitch to the octave and having the boost either always on or off.

Now I have another one to add to the backlog!


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## Coda (Jul 21, 2022)

I built a Rat just to see what the fuss was about. I ended up using a 308, again, just to see what the fuss was about. There is a difference, but I don't think its a better/worse difference. It sounds a little more low-fi with the 308. OP07 is fine, and actually sounds a bit more natural to my ears. TL072 was good too...even though I didn't remove the compensation cap (TL072 has an internal compensation). I still prefer the DS-1, but then, I use distortion to drive a BMP...


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## MichaelW (Jul 21, 2022)

I've been playing around with the hitting the Rat with the MBP Oracle Compressor on my P90 neck pickup. Man, with the sustain and the quality of the drive I'm getting a real early Robert Fripp type sounds. Sustain without a Fernandez Sustainer. Very cool stuff.


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## swelchy (Jul 21, 2022)

MichaelW said:


> Thanks @swelchy! I do have a second Rat board to build. I might just stick that in a 1590B instead of 1590A.
> 
> Did my care package make it to you?


Not yet but if your return addy is on there I’ll send you a goody package right back your way or DM it to me?


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## MichaelW (Jul 21, 2022)

swelchy said:


> Not yet but if your return addy is on there I’ll send you a goody package right back your way or DM it to me?


Yah it's stamped with the official Wong Family Crest Give me a DM when the Ge's show up. I hope I put enough postage on it.


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## HamishR (Nov 3, 2022)

I built a Rat recently - used a bass pot which I think makes it even more useful. And I have a few metal can LM308Ns I got from Small Bear not too long ago so used one of those and yes, there definitely is a difference. I had used CA3130s before and they still sound good. But the LM308N is kinda fatter or something. Plus being a metal can IC it has major mojo points. I personally don't believe in mojo in pedals but I am fascinated that chips were once made in what looks like a Ge transistor shell!


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## JamieJ (Nov 3, 2022)

The ruetz mod is a must for me on a rat. It just takes a bit of that harsh mid range out that I don’t like. That’s what I did on my mischief machine build. With the knob all the way CCW it is great on bass and all the way CW it’s the normal rat. I have mine at about 9 o’clock.

Great work as always @MichaelW


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## Chuck D. Bones (Nov 3, 2022)

spi said:


> I've used an out of spec 2n5457 in a Rat and it worked fine.  It's a buffer here, and the requirements are more forgiving than other applications (hence you can use a 2n5458 or a j201, which are both "out of spec" from a 2n5457 in different directions).  Pop in one of your out spec ones--if it works you can save a good j201 for another project.


Agreed.  What we really want there is a JFET with a high Vp, like 3-5V if you have one.


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