OD308 and RAT stuff anyone?

I'm just curious if anybody has had any experience with Monte Allums OD308... I'm considering one based on the outstanding quality of the results I've gotten from some MODs I purchased from him. Sounds like it is somewhat similar to a RAT...

I'm also curious what people's experiences have been with RAT type pedals. What did you like about them, what did you no like, etc. I'd be running this with an OCD, Blues Driver, and TS9DX and am just looking for something "different" but useful. Any thoughts would be greatly appreciated.

Thanks!

No experience with Monte Allums' stuff (though I've heard many good things about him) so no help there...

While they're not quite the same, the OCD and RAT tend to cover the same sonic territory. If I were to use both in my chain, I'd make sure they were set up quite differently (I have a Cool Cat Drive, which is a clone of the OCD) so I'd have more colors on my sonic palette-think lighter blue, and darker blue, if you will...

Franc Robert

The Rat is a unique pedal, because the LM308N is a unique op amp chip.

...The 308 has absolutely terrible slew rate characteristics, which makes it horrible for hi fi applications. But it's the exact thing that makes it superior for a dirt pedal. When almost all other op amps "hit the rails," they just plain sound bad. This is why clipping diodes and other circuitry is necessary to harness and clamp the signal, in an attempt to keep the tones in accord.

Another "advantage" to the 308 is that it requires external compensation to keep it from oscillating or behaving in a way that defies it's basic function. Most other chips (4558, TL072, etc.) are internally compensated - they are stable and behave well, but you can't manually alter them. The Rat uses a 30pF cap to externally compensate the 308. But a few folks who've spent a great deal of time tuning the circuit have found that you can go as low as 7pF, and get even better perfomance. I actually "compromise" with a 10pF cap, as they are extremely common.

My personal thoughts on the Rat:

Likes -
Mean, gritty, immediately recognizable unique clipping characteristics - it can go tight, loose, fuzzy, and they all sound good for some crazy reason.

Killer midrange that you typically only hear from either certain guitars, certain amps, or certain speakers. Very rare to hear it from a pedal, especially one as old as the Rat.

It does really good OD as well, IMO, by simply cranking back the distortion.

The passive tone control does a great job of "not getting in the way" like it can with other pedals, even if it is a bit limited in what it can do.

The Rat is also a rare pedal that seems to work great with most amps, big or small, and at most volumes. It doesn't really seem to discriminate that much.

Dislikes -

The very charming and signature EQ characteristics can be stifling at times, because they aren't very flexible.

If you're used to dialing in one specific tone, the Rat may not do it for you. It may be a bit loose at your preferred amount of distortion.

While the filter control is very open and allows for a lot of dynamics, it doesn't have as strong of a comprehensive sweep as most other tone controls. But if you alter it, you tend to kill something that is magical about the trademark Rat sound, IMO.

If you use a bunch of different dirt pedals, the Rat may sound a bit overt in comparison, even at reduced drive levels. While many revel in this, there are quite a few that get driven away by it.

-----------

As far as tweaking the Rat, I've found it to be a bit counterintuitive. Tantalums sound great in it, and they sound like garbage in almost all other pedals, IMO. Not only that, but metal films sound rather bland, also IMO. And the stock silicon clipping diodes are perfect as is, IMO. Lots of folks replace them with everything under the sun, but ProCo got it right the first time. You can get some cool tones with the diodes pulled, but IMO that isn't the Rat's strong suit. It was made to distort, compress, snarl, bark, and just make a lovely mess of things. It was not a design that should have been cleaned up, IMO.

The Bixonic Expandora uses a battery of LM308N chips, and is an equally chaotic and unique sounding pedal.

I couldn't imagine the average person finding anything other than typically positive thoughts about the Allums pedal. The magic is in the chip, and he doesn't stray that far from the original formula.

The Rat is a unique pedal, because the LM308N is a unique op amp chip.

...The 308 has absolutely terrible slew rate characteristics, which makes it horrible for hi fi applications. But it's the exact thing that makes it superior for a dirt pedal. When almost all other op amps "hit the rails," they just plain sound bad. This is why clipping diodes and other circuitry is necessary to harness and clamp the signal, in an attempt to keep the tones in accord.

Another "advantage" to the 308 is that it requires external compensation to keep it from oscillating or behaving in a way that defies it's basic function. Most other chips (4558, TL072, etc.) are internally compensated - they are stable and behave well, but you can't manually alter them. The Rat uses a 30pF cap to externally compensate the 308. But a few folks who've spent a great deal of time tuning the circuit have found that you can go as low as 7pF, and get even better perfomance. I actually "compromise" with a 10pF cap, as they are extremely common.

My personal thoughts on the Rat:

Likes -
Mean, gritty, immediately recognizable unique clipping characteristics - it can go tight, loose, fuzzy, and they all sound good for some crazy reason.

Killer midrange that you typically only hear from either certain guitars, certain amps, or certain speakers. Very rare to hear it from a pedal, especially one as old as the Rat.

It does really good OD as well, IMO, by simply cranking back the distortion.

The passive tone control does a great job of "not getting in the way" like it can with other pedals, even if it is a bit limited in what it can do.

The Rat is also a rare pedal that seems to work great with most amps, big or small, and at most volumes. It doesn't really seem to discriminate that much.

Dislikes -

The very charming and signature EQ characteristics can be stifling at times, because they aren't very flexible.

If you're used to dialing in one specific tone, the Rat may not do it for you. It may be a bit loose at your preferred amount of distortion.

While the filter control is very open and allows for a lot of dynamics, it doesn't have as strong of a comprehensive sweep as most other tone controls. But if you alter it, you tend to kill something that is magical about the trademark Rat sound, IMO.

If you use a bunch of different dirt pedals, the Rat may sound a bit overt in comparison, even at reduced drive levels. While many revel in this, there are quite a few that get driven away by it.

-----------

As far as tweaking the Rat, I've found it to be a bit counterintuitive. Tantalums sound great in it, and they sound like garbage in almost all other pedals, IMO. Not only that, but metal films sound rather bland, also IMO. And the stock silicon clipping diodes are perfect as is, IMO. Lots of folks replace them with everything under the sun, but ProCo got it right the first time. You can get some cool tones with the diodes pulled, but IMO that isn't the Rat's strong suit. It was made to distort, compress, snarl, bark, and just make a lovely mess of things. It was not a design that should have been cleaned up, IMO.

The Bixonic Expandora uses a battery of LM308N chips, and is an equally chaotic and unique sounding pedal.

I couldn't imagine the average person finding anything other than typically positive thoughts about the Allums pedal. The magic is in the chip, and he doesn't stray that far from the original formula.


Amen I say to this. I have been a rat user ever since I began playing. The only part I don't agree with is that they got it right with silicon diodes. I like the tone of my germanium diodes better for the type of music I play. more "sag" (is that the right word?) than the tighter silicon. But they all sound great, even the LED driven turbo rat. they have their applications.

Wow, that is some terrific information everyone! Thank you so much for taking some time to lay it out there for me!

mmmmm I love my rat

I love the stock RAT, and I love my Monte Allum modded RAT even more. 11 gauge that's probably the best description of a RAT I've ever read.

mmmmm I love my rat

+1

Nothin' like 'em