Obsidian Fuzz MKIII - RimRock Effects

Comfort Player

Gold Supporting Member
At last I am happy to introduce the Obsidian Fuzz MKIII from RimRock Effects. A small footprint NOS OC75 Black Glass fuzz for the masses.

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The Obsidian Fuzz is constructed from modern audio grade components and paired with legendary NOS Mullard Black Glass OC75 Transistors to deliver tone reminiscent of numerous members of the rock and roll hall of fame. The Obsidian started with the design idea of delivering a MKIII fuzz in a smaller package that could take advantage of modern power supplies, with "the" transistors, all at an affordable price. Measuring in at only 4.3" x 2.34" x 1.06" the Obsidian preserves precious board space, works with modern power supplies and utilizes true bypass switching so your tone is unaffected when not engaged.

Make no mistake, if you are looking for that Sola Sound MKIII sound without taking out a second mortgage give the Obsidian Fuzz a try.


Another basic clip from me and me son... I am not a recording studio, sorry. We stuck a mic in front of a Fender Blues Jr to see how it would mic.



Señor Member
Silver Supporting Member
I would've liked to spend more time with the Obsidian this weekend, but this head cold got the best of me!

In short, I really dig it. It's extremely versatile, and it can get nasty. I rarely use fuzz traditionally (vintage fuzz, anyway).. By that, I mean that I like to put buffers in front and/or rarely use them as standalone dirt. Plus, all of my distortion and fuzz runs in front of and through the Mythical Overdrive so I can use the MO's Tone knob as an EQ/filter for my overall tone.

BUT! Back to the fuzz.. The Obsidian isn't a clean up fuzz. You can change the dynamics by rolling off your guitar's Volume knob, sure- but it's full on nasty. And like the MO, it's meant to be played into a cranked amp. Otherwise, you won't likely hear the best is has to offer.

Inside, there are 2 trimpots: one controls the bias for Q1/Q2, the other sets the bias for Q3. I would highly recommend marking the set points before tweaking- mostly because I feel they're set perfectly by Ken before shipping. But I do understand that temperature can throw that off a little!

I like the Q1/Q2 trimmer right where Ken set it. Too far clockwise, and the fuzz gets choked & crackly. The Q3 trimmer can also choke the fuzz tone a bit, but it mostly just cuts the sustain or adds to the "openness" of the fuzz.

The Tone and Fuzz knobs are interactive too, so there are plenty of great sounds to be found. I really, really dug it with my tweed Champ clone and NOS Blues Jr.

Two thumbs way up, Ken!
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. . . . Plus, all of my distortion and fuzz runs in front of and through the Mythical Overdrive so I can use the MO's Tone knob as an EQ/filter for my overall tone. . . . .

That's an interesting arrangement, I've placed the MO at the beginning of my signal chain and it's always on using it to shape the guitar sound as it drives other pedals. Placing pedals before the MO is great idea for it will help shape the final tone into the amp. I'll have to try that tonight.

snow and steel

Silver Supporting Member
So mine arrived and I've been playing with it quite a bit.... oh man... I swear ALL the fuzz tones are here!

So I put the fuzz on full and the volume at about 75% and starting toying with the tone knob. With the tone knob way to the bass side [say three o'clock o'clock] its damn near a big muff, but with a bit more mids [and that's a good thing]. Gilmour tones are relatively easy to pull off here. Comfortably numb solo - easy! With the tone knob way to the treble side [nine o'clock] it almost sounds like AM transistor radio fuzz [ which is a really cool effect for some songs/things]. Cant get no satisfaction - Easy! And of course for those byrds/page tones I was after; I like it slightly to the treble side [eleven o'clock-ish] and it gives a TON of those awesome early byrds tones and jimmy page fuzz tones I was after. Heart full of soul - EASY! Just a touch more back [noon on the tone dial] and you have instant "Cherub Rock" by smashing pumpkins - easy! Now leave that tone knob where its at, put the volume on full and the fuzz all the way to the left - Foxy Lady!

I'm literally STUNNED at how many great tones there are in this box. I'm not a fuzz fan - never really used it before this box, but I can foresee me using it a LOT in the coming months! SO much fun!

Can't believe people aren't buying these faster than they can be made!

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