Anybody swap the chip in their rat, or clone ? I've hear a little about it, but nowhere near the buzz as chip swap in the screamer or even the tim. If anybody has experimented with the rat chip, I'd sure be interested in the 411.
The LM308 is generally considered to be the reason the Rat sounds so good. The newer ones come with a different chip so most people swap to the LM308. I have a Rat that looks like this: It came with another chip, I forgot the number but I have never heard of it before and I've swapped a lot of chips in my Timmy, Silver Kiss, etc. It sounded pretty good with the crappy chip in it, but it sounded much better with the 308. If anyone is doing any chip swapping in the Rat, it's to get rid of the cheap, crappy chip and put the LM308 in there like it should be.
Technically the LM308 is a less quality chip compared the the more quiet TL071. LM308 has a certain sound, but at the cost of noise. The TL071 that I use in my modded RAT, sounds good to me tonally with reduced noise.
The LM08 is externally compensated unlike the TL071. That means it needs an external capacitor to create the special "slew rate" distortion that gives the rat its special sound. But Guess what? The TL070 is ALSO externally compensated so it can be configured to prduce the same special sound the LM308 does. AND its a MUCH better sounding and MUCH lower noise chip than the LM308. As it happens Small Bear electronics carries the TL070. Swap the chip and swap the original 47pf compensation cap for 180 pf. If thats a bit too smooth lower values like 150 or even 120 pf caps will make it brighter.
I like fr8_trane's RAT. I have the Keeley. I can't say which I like more, actually. . . they are two different pedals in some ways, especially in volume. They both have great low end and excellent high-gain drive. He likes a smoother distortion, usually, whereas I like mine to be hairy in a fuzz-like way. Actually, the RAT killed my jones for fuzz, as I found fuzzes to be too finicky with other pedals. One day, however, I'm going to make him provide a socket for swapping chips so I can fiddle a bit that way. . . that would be at the limits of my ability to mod pedals
My rat has more mods than just the chip swap. It also has a bit more bass and is WAAAY less noisey than the Keely. Part of that is the chip swap part of it is extra filtering. Anyway, the TL070 is best chip if you want to cop the 308 tone with less noise and a bit smoother texture. If you remove the comp cap you can use just about any single chip like the tl071. They will all sound different but you might like one over the others
308's come as metal can versions, which tend to be less reliable, but if you get the lucky chip, it'll sound amazing
I have several dip-8 LM308s... they are not hard to find... I believe Small Bear has them. TL070... good call as a more exacting alternative to the LM308. I personally like the sound of the TL071 and they are readily available at Mouser.
Fr8, if I put a TL070 in place with the same value cap as LM308, what happens ? Does it feed back or sound less than good ? Interesting you say its smoother, I certainly have no reason to doubt that. Do you have any rat TL070clips ? Ever try NE5534 ? I like the LM308, but am always on the quest for better sounding, better feeling and responding overdrives, as an alternative to cranking tube amps way up .
I have a brown rabbit that I recently changed chips. I like both chips, but for a fuzzier sound I kept the LM308 (vintage one from my understanding). I think the pedal isn't really amp like. It sounds like a Rat. It has amp like qualities but nothing like say my old Bogner. A big part part of getting a great sound from these pedals is cranking the amp. I have a pretty loud amp so by the time I go to 3 or 4 it's plenty loud. The change in sound however was not a huge difference to the common ear. I noticed it because I am being picky with my sound. I still am looking for the high gain amp sound from a pedal. In the mean time I am super happy with my set up.
On one of the past threads on Rat mods,some guy did extensive chip swapping and the best(according to him) was a OA81 with half of an AC125.I have'nt got around to trying it myself though.
The Rat is one of the few pedals where switching out the opamp will make a noticeable difference in the sound... I like the NE5534 if only for the lower noise that it provides, and crisper sound. regards, Jack
The stock 47pf cap would probably make the TL070 sound incredibly bright and might even cause it to oscillate/squeal. I never tried the NE5534 just the TL070 because it is so similar to the 308 with less noise. If you search diystomboxes.com for rat, tl070, lm308, compensation cap, etc. You will find more info concerning the rat than you would ever want to know. BTW my mods are all based on the AMZ-FX Rat booklet he sells for $7. You can make your rat smoother, less noisey, and add more bass by swapping a few parts as per the instructions. The Amz mods do reduce the overall output volume though. Unity gain is 2:00 now where before it was 11:00.
