Gruntbox - a tentative bass fuzz

Mark Hammer · February 20, 2009, 06:30:46 PM

I wish I could tell you. The prototype is in the hands of a guy who just moved to Israel, and I don't have any drawings other than what is posted. The tone pot was linear, and the two other pots were log. Sorry.

bytedog · October 01, 2009, 04:45:37 AM

Vero or PCB anyone?

mr.adambeck · October 01, 2009, 01:15:37 PM

Any sound-clips of this one? The bassist in my band/my fiance, is always looking for good bass pedals!

spaceace76 · February 13, 2010, 01:03:24 PM

what opamp is used in the gruntbox? haven't seen it mentioned anywhere

geertjacobs · February 14, 2010, 04:53:18 AM

From post #1:

QuoteThe quad op-amp (LM324/TL074 pinout shown) is used entirely in inverting mode.

spaceace76 · February 14, 2010, 06:19:13 AM

ah of course, right in front of me the whole time! now that you've pointed it out though, it's impossible to miss. thanks!

mothercruncher · May 28, 2011, 05:01:45 AM

Hi all,

Has this, rather excellent sounding, project withered on the vine now?
Having begun to play bass recently, I'm a bit fed up of adapting pedals I've built to also work on bass and think the little fella deserves something specific

Did anyone ever make up a vero layout for this?

johnk · July 23, 2013, 03:09:28 PM

being a bass player since 1967 and liking the concept of this circuit, I drew up a vero of it and built it last night. it works as specified, and I sincerely mean no offense, but it's just not what I look for in a bass fuzz at all.
the (fizzy) fuzz is completely separate from the clean signal and there's no 'cohesiveness' between the fuzz and clean tones whatsoever (I guess that was the intention). the clean tone control does almost nothing (probably could use a larger cap value).
personally, I think it would be a lot better if the amount/gain of distortion was adjustable, possibly had its own tone control, and had a fuller range to it. the pre-set amount of fuzz just sits on top of the clean signal and all you get to do is blend it in.
if anyone would like a copy of my vero for it, just ask and i'll post it.

Mark Hammer · July 23, 2013, 03:28:42 PM

Absolutely no offense taken. It was an experiment, and I fully understand that it is easier to arrive at a mutually agreed-upon list of toppings for a single extra-large pizza for 12 than it is to arrive at a distortion that makes even a quarter of potential users happy. Personally, I think the drawing is actually better than the tone, and the only reason people keep attempting it is because there just aren't that many distortions out there that declare themselves explicitly for bass.

hack away, and if there are elemtns you want to custom tailor, feel free to pop me a note and we'll conspire.

Bill Mountain · July 23, 2013, 04:04:59 PM

Quote from: johnk on July 23, 2013, 03:09:28 PM
being a bass player since 1967 and liking the concept of this circuit, I drew up a vero of it and built it last night. it works as specified, and I sincerely mean no offense, but it's just not what I look for in a bass fuzz at all.
the (fizzy) fuzz is completely separate from the clean signal and there's no 'cohesiveness' between the fuzz and clean tones whatsoever (I guess that was the intention). the clean tone control does almost nothing (probably could use a larger cap value).
personally, I think it would be a lot better if the amount/gain of distortion was adjustable, possibly had its own tone control, and had a fuller range to it. the pre-set amount of fuzz just sits on top of the clean signal and all you get to do is blend it in.
if anyone would like a copy of my vero for it, just ask and i'll post it.

Great to see you here John. This is FatherofFires from talkbass.

And for those who don't know. This guy is a building machine:

http://johnkvintageguitars.homestead.com/Overdrive-Pedals.html

And a huge inspiration.

bluebunny · July 23, 2013, 04:37:18 PM

Quote from: Bill Mountain on July 23, 2013, 04:04:59 PM
Great to see you here John. This is FatherofFires from talkbass.

And for those who don't know. This guy is a building machine:

Wow!

Welcome, John!

johnk · July 23, 2013, 05:23:46 PM

thanks guys.
and thanks Mark for posting the schematic.
I'll probably experiment with the circuit to see if I can get it where I want it, but I need to finish up a couple other pedals soon.
IMO, it definitely has potential.

Mark Hammer · July 23, 2013, 06:22:26 PM

Quote from: johnk on July 23, 2013, 05:23:46 PM
thanks guys.
and thanks Mark for posting the schematic.
I'll probably experiment with the circuit to see if I can get it where I want it, but I need to finish up a couple other pedals soon.
IMO, it definitely has potential.

Did you mean "a couple" or a couple dozen?

ashcat_lt · July 23, 2013, 11:47:09 PM

My experience with a pedal very similar to this is that it really benefits from compression on the clean side. The distorted side has no dynamics whatsoever, and that's why it seems to ride on top of the clean tone. I put an effects loop going into each side, but we've ended up just sticking the comp in front of the pedal itself. Subtly different effect from in the loop, but it works better for our situation.

Then it can take some fiddling. I had to do some silly things to balance the gain, voice the distortion, voice the LPF on the clean side, and get the blend pot to offer a useable sweep.

I agree that it would be more flexible with more knobs, but there are a lot of good tones in mine, from a subtle "bass expansion" type thing that adds just enough first octave to help the bass translate on small, bass-deficient systems, to a pretty nasty buzz saw thing. I had Les Claypool's bi-amped system in mind when I built it, and there's definitely a little bit of Pork Soda in those two knobs.

I guess I'm not trying to hijack this thread, just trying to defend the basic premise. It can work. I don't have a schematic to show you. It's three buffers (one with a little gain), a wide open Rat, and a whole bunch of half-assed, dimly remembered hacks dreamed up in simulation and then "perfected" on the breadboard. If I had it to do again I might try to put a compressor inside the thing, but I highly recommend the loops. Put a wah on the distorted side, or a phaser, maybe a delay...

Edit - rather than double post, since there have been no replies.

Reading that other thread re: adding dynamics I had the idea that we could maybe do the opposite of what I suggested above and add some expansion to the distorted side so that it follows the clean a little better. But then, if you just used a more "transparent" circuit for the distortion...

Honestly, though, if you're actually looking for ultimate flexibility you'd be better off just building a Buff N Blend or other splitter/mixer/looper thing. That's really all this thing is.

carlosjofernandez · January 20, 2016, 11:56:33 PM

Hi !, I have built this fuzz and have made a PCB. This pedal sounds nice and smooth, ideal for funky bassists. The tone control makes almost nothing, nevertheless that is ok.
Here you are: https://mega.nz/#!TYBGXBga!gwbFQNR6FDhhkYmFqI5b3ZUrqnNIa83l3eeQS__-_3A

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Gruntbox - a tentative bass fuzz