I've built a Rat clone, and it's definitely on the grungy side of things as the gain goes up.
I've had a number of different Rats and Rat-a-likes over the years, and they've all had their own thing going on.
The first Rat 2 I had was quite grungy and boxy sounding with the gain over 1/4. This clone I've made is is about the same. Once the gain's up towards half, you can run the filter at 0 - wide open - and it's not particularly harsh.
I had a '90s US rat with the lm308 which was a lot brighter - you had to run the filter up around 3/4. But consequently, if you wanted to turn the gain up you could roll the filter back and get some clarity/ articulation at higher gain. Wish I hadn't sold that one! And I had a big box rat in 2010 for a while, it had bigger lows and didn't feel as compressed.
People say there's nothing in the OP07 vs LM308, but it's such a simple circuit, so where are the differences, if not the chip?
My clone has the "Ruez" mod on a pot, I set it by ear then measured the pot, and I picked... 50 ohms (stock is 47).
Comments
It all adds up
I have a 2002-ish early MIC Rat2 with slightly shitty pots and no LM308N and a blue switch, and a Fuzzdog with decent pots and the "right" chip, and a cloned JHS All American. Of those I prefer the Rat2. The Fuzzdog is really really great in a gritty snarly sort of way, but I find the Rat2 is a bit more chuggy and sits in a mix better. I'm willing to bet it's as much down to component tolerances as it is the chip.
The All American is interesting, but I haven't spent enough time with it lately to remember a detailed opinion.
Do they still make them? How does a company like Mooer get enough to make their Black Secret (which I also thought sounded on the grungy side of things)? If they are legit, do they make them like they used to?
By which I mean, the heart of the circuit involves running an op amp into overdrive - sure, most of the distortion is coming from the diode clipping that follows, but it obviously matters what the op amp feeding that it putting out. Are all LM308s made equal, in regards to what they do when they're distorting?
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The rest is down to the surrounding circuitry, especially the tone filtering (both at the filter control and the preset bass cuts), but the circuit is so sensitive that even the type and quality of the components, especially the pots, seems to matter - this is the big difference between the US and Chinese ones, not the IC.
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