RAT op amp question

[radam84]

so Im thinking of building a vero board RAT(it'd be my first). I have essentially everything on hand 'cept the footswitch and op07,lm308, etc. I was looking at random crap Ive got kicking around and found an old MC33201, it has the same pinout as the lm308 and a fairly low slew rate (.5min, 1.0typ) however I dont understand much of what Im looking at on a datasheet. Is this old chip something that would work at all without changing anything else on the board layout? If it does work what would be the expected differences if any?

 

[spi]

Looks like it should work. You should use an IC socket. If it doesn't work out, you can audition other chips until you get one you like.

You wouldn't need the slew/compensation capacitor, but I would include it anyway, so if you were to later swap it with a lm308, it'd just work.

 

[radam84]

Looks like it should work. You should use an IC socket. If it doesn't work out, you can audition other chips until you get one you like.

You wouldn't need the slew/compensation capacitor, but I would include it anyway, so if you were to later swap it with a lm308, it'd just work.

Ok awesome guess that means Ill start throwing stuff together today... Still gotta order some jacks and footswitchs but at least I can begin and see what happens, thanks for the reply eh, cheers.

 

[hamerfan]

i use pin sockets for the comp cap. So i can swap it in when i use different opamps. Recently i like my rat pedal with a more cleanish NE5534 opamp. A rat is a quite flexible distortion with the NE5534 or a CA3130 and the hard clipping diodes off.

 

[Coda]

TL071 is fun in a Rat…

 

[radam84]

TL071 is fun in a Rat…

Ive heard this as well, but have also read that the lower slew rate of the lm308 is what gives the rat its "qualities" and iirc the tl071 is like 100 times higher slew rate. Honestly I dont know what that means but Im leaning towards as original as possible. I like the idea of it being able to do a slight boost and then go althe way into fuzz territory. What would the slew rate alter out of curiosity? Thanks for suggestion though.

Looked up the slew rates, 100 times was definitely incorrect but .3 compared to 13 seems like a large difference, maybe its not I really don't know lol.

 

[Coda]

Ive heard this as well, but have also read that the lower slew rate of the lm308 is what gives the rat its "qualities" and iirc the tl071 is like 100 times higher slew rate. Honestly I dont know what that means but Im leaning towards as original as possible. I like the idea of it being able to do a slight boost and then go althe way into fuzz territory. What would the slew rate alter out of curiosity? Thanks for suggestion though.

Looked up the slew rates, 100 times was definitely incorrect but .3 compared to 13 seems like a large difference, maybe its not I really don't know lol.

It’s more transparent sounding, to use an adjective that isn’t used enough now days…

 

[radam84]

Ok right on, cause I plan on the timmy as an overdrive. Thought a RAT/Timmy combination would give me almost everything I need, 'cept I plan to grab a rowin frenzy fuzz or build the wooly mammoth.... And then, my bases will be covered for sure lol.

 

[Feral Feline]

Socket the IC and the compensating cap — then you can audition all sorts of ICs, and even experiment with different values of the compensation cap.

It's great to try a completely stock Rat as a baseline, but if your ears like the TL071 or prefer the BJFE-ish tones of a CA3130 then so be it and damn originality & conformity!

 

[radam84]

Socket the IC and the compensating cap — then you can audition all sorts of ICs, and even experiment with different values of the compensation cap.

It's great to try a completely stock Rat as a baseline, but if your ears like the TL071 or prefer the BJFE-ish tones of a CA3130 then so be it and damn originality & conformity!

I grew up on punk rock and from demo videos Im thinking the stock rat sound is what Im looking for but that said, I do plan on doing exactly that and experimenting because, hell why not.

 

[Feral Feline]

Digging your avatar @radam84 !

 

[HamishR]

Well a true punk rock ethos would suggest that you simply use what is on hand. I like a Rat as much as the next guy but it doesn't have much low end grunt. That might work for you but I like to add some. I've built Rats with all sorts of different ICs and haven't noticed much difference. I really like my metal can LM308Ns because, well, they're metal can LM308Ns. Not because they sound inherently better but because metal can LM308N.

 

[radam84]

Digging your avatar @radam84 !

Ya like that eh, right on. Yea I wasn't gonna put it up until after building a RAT (first build) but figured screw it why not now lol. The RAT will be my first build either way.

 

[radam84]

Well a true punk rock ethos would suggest that you simply use what is on hand. I like a Rat as much as the next guy but it doesn't have much low end grunt. That might work for you but I like to add some. I've built Rats with all sorts of different ICs and haven't noticed much difference. I really like my metal can LM308Ns because, well, they're metal can LM308Ns. Not because they sound inherently better but because metal can LM308N.

I did find a site to buy some and was really thinking about it, but because Im essentially doing this to save a few bux Im going as cheap as possible for starters but I imagine Ill get the "virus" and start building bunches. So when the time comes Ill build something nice and fancy like lol.

 

[spi]

I did find a site to buy some and was really thinking about it, but because Im essentially doing this to save a few bux Im going as cheap as possible for starters but I imagine Ill get the "virus" and start building bunches. So when the time comes Ill build something nice and fancy like lol.

Careful where you buy it, lots of illegitimate ones out there. Check in here before you buy and folks will steer you right. I bought my lm308 can from ebay because the seller was vetted by others here.

 

[HamishR]

I got a bunch from Small Bear when they had them a little while ago. I'm not really a fan of the Rat (!) but seeing as BJF uses the Rat as a starting point for quite a few pedals I thought it worth investigating. What else am I gonna do with my time? I have ended up making pedals which suit friends better so they buy them off me. Win-win.

 

[radam84]

Careful where you buy it, lots of illegitimate ones out there. Check in here before you buy and folks will steer you right. I bought my lm308 can from ebay because the seller was vetted by others here.

so I thought I saw some NOS at electronic goldmine. Just looked again though and have a feeling I mistook a 309 voltage regulator for the metal can 308's I mentioned in my previous post, lol. Whoops.

 

[Feral Feline]

If you need more low end in your Rat, I recommend the GTranter mods.

 

[radam84]

If you need more low end in your Rat, I recommend the GTranter mods.

OK cool, Ill look into it, thanks eh.