I’ve only just tried my first proper Rat/Distortion for bass in the last year.
I’ve had a couple fuzz pedals (mainly a Pork & Pickle) but I can’t get over how fizzy the top end gets on most.
Snagged a Locust Star a while ago and I love it. I know I started with a good one, but I still want to try a couple more. Amp Grinder is at the top of that list.
What are your tone goals? I like grindy, heavy Rat tones that fit with various metal styles. I've had plenty of Rats the past few years, and here is an incredibly short breakdown:
Volt Thrower: My #1 - incredibly flexible, retains all the lows, cuts, nice and grindy. But can do pretty much anything. Takes time and patience to tweak. The dirt/grit is always present.
Locust Star: Incredibly close #2, and very similar for my needs. Easier to tweak, but slightly more treble bite, making it less smooth, and less desirable overall. Could very easily do almost identical tones to the VT - I'm splitting hairs, here. I ALWAYS run it at 18v as I prefer the headroom, which I find noticeable.
Tremond - Excellent and underrated. Always retains lows, and easiest to get lower gain tones from, as well as easiest to tweak - almost every setting is quite usable. I use this as a complementary Rat tone to the other two, but it's also excellent. The dirt/grit can blend in a bit more than the others.
Bass Mountain - The high gain counterpart to the Tremond. Same basic review as the Tremond, but use "higher gain" instead of "lower gain". Seems easier to get aggressive tones from, but tougher for lower gain tones.
Blower Box/Deluxe - Deluxe is the better option, no doubt. Both have a high end hiss that I dislike, so they didn't stay. Deluxe retains lows better and is more flexible. The dirt disappears in the mix, but leaves incredibly punchy bass that cuts. Perfect for faster riffs.
I’m not sure how useful my comparison will be.
I find the LS to sound good, but not great for what I want out of it (light grind, not too much drive). The control set makes it very flexible, but it’s the most un-rat like of the rat based circuits I’ve tried.
Others I’ve tried include the Blue Colander Tremond and Comodoro Rat Bass.
The Comodoro was my go to for a grindy tone until the Amp Grinder showed up. It just sounds a little more full and mean. The low passed clean blend is pretty much perfect. It lets you add back in any bottom end that you might be lacking depending on your level of gain. It really doesn’t sound anything like the LS.
The LS and Volt Thrower can do about any Rat tone, but take tweaking to get there. The Tremond is perfect for the low gain tones you mention.
I need to try an Amp Grinder one day.