# Muroidea (RAT)- LM308 vs. ???



## bakewelder (Mar 8, 2021)

I put a CA3130EZ in my Muroidea build and its noisy. However, i am on the fence with what should be considered acceptable noise since I don't have an original  RATto A/B with. Any thoughts on switching to OP07 or other?


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## Danbieranowski (Mar 8, 2021)

bakewelder said:


> I put a CA301EZ in my Muroidea build and its noisy. However, i am on the fence with what should be considered acceptable noise since I don't have an original  RATto A/B with. Any thoughts on switching to OP07 or other?


Supposedly OP07 is what the production run Rats use now. I've used both and liked both.


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## Barry (Mar 8, 2021)

I got a stash of 308's so I'm good


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## Chuck D. Bones (Mar 9, 2021)

WTF is a CA301EZ?  If you mean CA3130, I use them in my Mojito pedals and there's no noise problem.  Maybe you got a bad one.  OP07 is a good option.  You can also try other single opamps like LM301, TL071, LF351 or (barf) LM741.


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## bakewelder (Mar 9, 2021)

Chuck D. Bones said:


> WTF is a CA301EZ?  If you mean CA3130, I use them in my Mojito pedals and there's no noise problem.  Maybe you got a bad one.  OP07 is a good option.  You can also try other single opamps like LM301, TL071, LF351 or (barf) LM741.


Typo. I corrected it in original post. I will give an OP07 a try. Thanks, as always!


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## spi (Mar 9, 2021)

Chuck D. Bones said:


> (barf) LM741


lol, is your barf comment in reference to use in a rat, or in general?

I used a LM741 in my dod 250.  Is there a better one I should consider for that circuit?


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## Chuck D. Bones (Mar 9, 2021)

Ha ha ha, in general.  LM741 is the Budweiser of opamps IMHO.  It was _the_ opamp to use back in the day, mainly because they were cheap and the good ones weren't invented yet. If you're going for total vintage, use a 741. Other opamps are lower noise and may or may not sound better in a DOD250 or MXR Distortion+.

Like Steve at Small Bear says:


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## benny_profane (Mar 9, 2021)

Chuck D. Bones said:


> Ha ha ha, in general.  LM741 is the Budweiser of opamps IMHO.  It was _the_ opamp to use back in the day, mainly because they were cheap and the good ones weren't invented yet. If you're going for total vintage, use a 741. Other opamps are lower noise and may or may not sound better in a DOD250 or MXR Distortion+.
> 
> Like Steve at Small Bear says:
> 
> View attachment 10254


I mean, he's not wrong. That picture will never not be funny.


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## manfesto (Mar 9, 2021)

Chuck D. Bones said:


> Ha ha ha, in general.  LM741 is the Budweiser of opamps IMHO.  It was _the_ opamp to use back in the day, mainly because they were cheap and the good ones weren't invented yet. If you're going for total vintage, use a 741. Other opamps are lower noise and may or may not sound better in a DOD250 or MXR Distortion+.
> 
> Like Steve at Small Bear says:
> 
> View attachment 10254


EHX is using the LM741 in their Flatiron Fuzz RAT clone.

because sometimes you don’t want fidelity!


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## Barry (Mar 9, 2021)

Chuck D. Bones said:


> WTF is a CA301EZ?  If you mean CA3130, I use them in my Mojito pedals and there's no noise problem.  Maybe you got a bad one.  OP07 is a good option.  You can also try other single opamps like LM301, TL071, LF351 or (barf) LM741.


I think somebody's been doing their taxes


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## dmnCrawler (Mar 9, 2021)

I did a thing with the Wampler if it helps.


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## mdc (Mar 9, 2021)

At the electronics store I go to sometimes in a pinch, they have a bin full of LM308Ns for $9/ea and a bin of LM208Ns for $1.50/ea. I always find that funny. 
Just because I was curious and because I socketed the opamp when I built a muroidea, I grabbed a few of each of the common choices (308, 208, OP07, CA3130, maybe one other I can't remember?) and honestly couldn't tell any real difference between any of them. I think the individual opamp has a lot less to do with how that circuit sounds than the fact that it's just "an opamp" in that circuit.


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## ANGRY_SWEDE (Mar 10, 2021)

bakewelder said:


> I put a CA3130EZ in my Muroidea build and its noisy. However, i am on the fence with what should be considered acceptable noise since I don't have an original  RATto A/B with. Any thoughts on switching to OP07 or other?


OP07 sounds great. It is a direct replacement for the LM308.


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## Barry (Mar 10, 2021)

mdc said:


> At the electronics store I go to sometimes in a pinch, they have a bin full of LM308Ns for $9/ea and a bin of LM208Ns for $1.50/ea. I always find that funny.
> Just because I was curious and because I socketed the opamp when I built a muroidea, I grabbed a few of each of the common choices (308, 208, OP07, CA3130, maybe one other I can't remember?) and honestly couldn't tell any real difference between any of them. I think the individual opamp has a lot less to do with how that circuit sounds than the fact that it's just "an opamp" in that circuit.


I think a lot of the Mojo in the Unicorn parts is listener bias, and I've seen studies have verified that


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## ANGRY_SWEDE (Mar 12, 2021)

Barry said:


> I think a lot of the Mojo in the Unicorn parts is listener bias, and I've seen studies have verified that


Totally agree. You hear what you want to hear. Better to look at the data if you want real answers.


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## Chuck D. Bones (Mar 13, 2021)

dmnCrawler said:


> I did a thing with the Wampler if it helps.


What exactly do you mean by pairing channels?  I see only one socket on the board.


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## dmnCrawler (Mar 13, 2021)

Chuck D. Bones said:


> What exactly do you mean by pairing channels?  I see only one socket on the board.


I recorded the looper audio through the Torpedo CAB into Reaper. I had a track for each of the ICs. I then lined them up, cut them up and mixed them in Premier Pro. No post processing on anything other than adding the Toontrack drummer and all 6 Rat tracks at the beginning and end of the video.

A9   - TL071
A10 - LM741
A11 - LM741 Metal Can
A12 - NE5534
A13 - LM308
A14 - OPA134

I should have said mixing the tracks not pairing channels. I was thinking of the channels I had paired up in Premier Pro.

 I am always happy to take suggestions on what people would like to see and hot to make myself better understood.


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## onemhz (Mar 14, 2021)

I finally got my order from Tayda and started as soon as I could get to my soldering station. But... somehow the 30pf caps are not in my order - I marked them off on the sheet meaning I put them in my cart!! Anyway - Can I just jumper the pads for the 30pf cap since I’m using an OP07 instead of the LM308? Trying to find an alternative to paying for shipping again and waiting... again.


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## Chuck D. Bones (Mar 14, 2021)

NO!!!
No jumper.  Leave the place for the 30pF cap empty when using OP07.  
OP07 does not need the 30pF cap.  It doesn't do any harm to install it, but it doesn't do any good either.


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## onemhz (Mar 14, 2021)

Ok. Leaving it out is even easier!! I read somewhere else it would probably have no effect but it wasn’t clear it could be omitted completely. Still learning about these circuits so I keep making bad assumptions that a missing component means a broken circuit. Did the same with the indicator LED on another board.
Thanks!


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## Kroars (Apr 7, 2021)

bakewelder said:


> I put a CA3130EZ in my Muroidea build and its noisy. However, i am on the fence with what should be considered acceptable noise since I don't have an original  RATto A/B with. Any thoughts on switching to OP07 or other?


Just in case, here’s a link to genuine National Semiconductor LM308’s for under $4 on sale right now:









						IC LM308N - Original Rat Chip for our best RATT Deluxe PCB - GuitarPCB
					

LM308N - Original Rat Chip for our best RATT Deluxe PCB




					guitarpcb.com


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