Planning a RAT...
- Thread starter Big Monk
- Start date
Harry Klippton
Well-known member
Why not start with the basics? Get a proco. They're cheap and readily available. Then you know what you're starting with before you try to squeeze the kitchen sink in there.
Big Monk
Well-known member
No Kitchen Sink. Straight up RAT. Just wondering which version or component values people have found works the best.
I know you said @thewintersoldier built one for you. Anything special about that one?
fig
Village Idiot
Do you mean other than @thewintersoldier built it?
Coda
Well-known member
I built one based on the original specs (LM308). It’s decent. However, I built it with the intention of swapping IC’s out…which I did. I tried several. They all basically sound the same. I think I actually preferred the part that is stock nowadays (OP07?), but put the LM308 back in because I wanted to see if it would spout magic. It hasn’t. I regret not socketing the LED’s l, though…
thesmokingman
Paid Hater
if you go the mod route, plan ahead and buy three replacement pots from smallbear and a 3n3 film cap along with your mojonium op amp of choice (lm108/208/308)
benny_profane
Well-known member
If you take a look at that sheet, there really isn't a lot of variance apart from clipping diodes, inversion of the TONE/FILTER wiring, those necessitated by choice of IC, bypass switching systems, coupling caps without appreciable changes in frequency response, and a pull-down resistor at the input. (Certainly not the wide variance seen with the BMP.)
In terms of mods, the Ruetz mod ("sweep" on the Aion board) or @Chuck D. Bones' CONTOUR control are useful and can be taken out of the circuit entirely. Clipping options are an obvious choice: I prefer 2x1 Si diodes (e.g., 1n4148 or 1n914), but usually include 1x1 LEDs (Turbo) and 1x1 Si (stock) as well with an On-Off-On toggle.
The 'White Face' small box Rat gets a lot of attention on the internet. It's the V2 FILTER control circuit. That being said, most Rat versions are the same circuit in different housings or aesthetics and claims about sonic differences are specious. The real change comes with the introduction of the OP07 chip (see below).
The Rat is definitely my favorite distortion. Stock, it's got a ton of options and is very versatile, but it can be easily modded to adjust things as necessary. It has a usable range from OD to distortion to fuzz [1] and it stacks well with (octave) fuzzes, ODs, and boosts. Frankly, I'm surprised I don't see more boards with two Rats on them. I don't really think it's terribly productive to argue about IC choice here [2], but I would encourage you to try different chips out and see what you like. The FILTER control can be narrowed to have more precision if you find that there's only a window that works for you.
It's a simple circuit and easy to bread board. I'd suggest building one stock and modding another one out. For inspiration beyond clipping and typical tone mods, the VFE Alpha Dog is a more ambitious take on a modded Rat.
1. There are a lot of varieties of 'fuzz'. It gets fuzzy at full-bore. We don't need to have an inquisition here.
2. There are a lot of questionable devices being sold as 'LM308' chips and not a lot of control over test methodology. Some unscrupulous stateside resellers purchase bulk eBay listings and pass them off as authentic. Are they? Who knows. SBE and other sellers with good reputations can be trusted, but there is a lot of uncertainty in the market.
In terms of mods, the Ruetz mod ("sweep" on the Aion board) or @Chuck D. Bones' CONTOUR control are useful and can be taken out of the circuit entirely. Clipping options are an obvious choice: I prefer 2x1 Si diodes (e.g., 1n4148 or 1n914), but usually include 1x1 LEDs (Turbo) and 1x1 Si (stock) as well with an On-Off-On toggle.
The 'White Face' small box Rat gets a lot of attention on the internet. It's the V2 FILTER control circuit. That being said, most Rat versions are the same circuit in different housings or aesthetics and claims about sonic differences are specious. The real change comes with the introduction of the OP07 chip (see below).
The Rat is definitely my favorite distortion. Stock, it's got a ton of options and is very versatile, but it can be easily modded to adjust things as necessary. It has a usable range from OD to distortion to fuzz [1] and it stacks well with (octave) fuzzes, ODs, and boosts. Frankly, I'm surprised I don't see more boards with two Rats on them. I don't really think it's terribly productive to argue about IC choice here [2], but I would encourage you to try different chips out and see what you like. The FILTER control can be narrowed to have more precision if you find that there's only a window that works for you.
It's a simple circuit and easy to bread board. I'd suggest building one stock and modding another one out. For inspiration beyond clipping and typical tone mods, the VFE Alpha Dog is a more ambitious take on a modded Rat.
1. There are a lot of varieties of 'fuzz'. It gets fuzzy at full-bore. We don't need to have an inquisition here.
2. There are a lot of questionable devices being sold as 'LM308' chips and not a lot of control over test methodology. Some unscrupulous stateside resellers purchase bulk eBay listings and pass them off as authentic. Are they? Who knows. SBE and other sellers with good reputations can be trusted, but there is a lot of uncertainty in the market.
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benny_profane
Well-known member
I haven't played one, but take a look at the schematics. Beyond the same FILTER control (with a value change) and hard clipping after the gain stage, there are a lot of differences. Though many of the differences are fulfilling the same functions as the corresponding Rat circuit blocks, the increased voltage, buffered bypass scheme, two-stage gain block, and JFET IC op amps used throughout make it a pretty different circuit. It certainly wears its inspiration on its sleeve, but I don't think I'd call it a 'Rat'.
Matmosphere
Well-known member
It's really all about the diodes. I have owned a couple Rats, my old bandmate had a Turbo Rat, and I've built a few as well. The diodes make a much bigger difference than using the modern op-amp vs a lm308. If I were going to build one again I'd do the standard clipping diodes and red LEDs on a switch.
The stock Rat is pretty great. The Turbo Rate (which is identical other than red leds for clipping) is a monstrous high gain beast of greatness that is loud AF. Both are worth having.
If I recall properly the You Dirty Rat is the same as the original but with no clipping diodes, just op-amp clipping. It's okay, but I don't like it as much. The nice thing is that if you use a three way switch instead of a two way you can have leds, the regular diodes, and no diodes without much trouble.
On top of that the Ruetz mod is also worth trying. I have made Madbean's Slow Loris. It that incorporates both a clipping switch and the Ruetz mod. I made a Runt as well, that one is a solid little board, dead stock rat, if you are a glutton for punishment and really want a 1590a Rat.
I'll leave you with this partia schematic for a Rat I believe to be from the development stage. (sorry if I already shared this here, I don't remember)
The stock Rat is pretty great. The Turbo Rate (which is identical other than red leds for clipping) is a monstrous high gain beast of greatness that is loud AF. Both are worth having.
If I recall properly the You Dirty Rat is the same as the original but with no clipping diodes, just op-amp clipping. It's okay, but I don't like it as much. The nice thing is that if you use a three way switch instead of a two way you can have leds, the regular diodes, and no diodes without much trouble.
On top of that the Ruetz mod is also worth trying. I have made Madbean's Slow Loris. It that incorporates both a clipping switch and the Ruetz mod. I made a Runt as well, that one is a solid little board, dead stock rat, if you are a glutton for punishment and really want a 1590a Rat.
I'll leave you with this partia schematic for a Rat I believe to be from the development stage. (sorry if I already shared this here, I don't remember)
Attachments
benny_profane
Well-known member
The You Dirty Rat uses antiparallel germanium diodes.
Edit: @mdc is correct below. New production uses BAT-41 diodes instead of the Ge used initially.
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Matmosphere
Well-known member
Couldn't remember, I know I don't like the germanium sound in there. Not terrible, just not very Rat.
mdc
Well-known member
AFAIK, The Dirty Rat hasn't used Ge diodes for years. It uses BAT41s or BAT46s with similar Vf ratings and (surprise) no one can tell the difference.
I love Rats a *lot* but I also kinda feel like the attempts to improve them are sorta missing the beauty of the pedal. It's just sort of a perfect thing as it is. Also, I honestly don't think the Rat2 and the Turbo Rat sound too different from one another, the Turbo Rat just has a lot more output volume. The Rat was my main (only!) pedal for years when I was touring in bands, and I switched to the Turbo eventually as it basically gave me the same sound with a bit of a volume boost.
I love Rats a *lot* but I also kinda feel like the attempts to improve them are sorta missing the beauty of the pedal. It's just sort of a perfect thing as it is. Also, I honestly don't think the Rat2 and the Turbo Rat sound too different from one another, the Turbo Rat just has a lot more output volume. The Rat was my main (only!) pedal for years when I was touring in bands, and I switched to the Turbo eventually as it basically gave me the same sound with a bit of a volume boost.
benny_profane
Well-known member
You're right about the BAT-41 diodes. I edited my post above.
I tend to agree with you about modding the circuit (beyond clipping diodes). Any mod I like to do with a Rat should be able to be taken out and the circuit returned to stock. Pedals like the VFE Alpha Dog are completely different circuits—that's not an appraisal or valuing of them, it's just that they aren't Rats.
I disagree w/r/t LEDs. You do get a volume boost when switching to LEDs from 1n4148/1n914, but you also gain an amount of headroom. If you normalize the volume between a Rat with LEDs and one with Si diodes, the LED-clipper will have less compression and more headroom/nuance comparatively.
benny_profane
Well-known member
Oh, the horse is out of the barn. If you want a straight-forward stock three knob Rat, you already have your answer. I'm taking advantage of the opportunity to talk about a Rat beyond nonsense about the IC. In a sea of fuzz, tube screamers, and the LM308, this is a rare opportunity.
Edit: To your original question: I would say build it.
Big Monk
Well-known member
I edited my post above to include a clipping switch because that seams useful as well.
benny_profane
Well-known member
SPDT On-Off-On: LEDs always in circuit (Turbo), symmetrical Si 1n4148 or 1n914 (Stock), and WILDCARD (I like asymmetrical Si).
