PedalPCB Gnat mod - "The Dizzy Elk"

peccary

Well-known member
First off: all credit for this goes to @music6000 , @thewintersoldier and everyone else who contributed to this build. You can see the original discussion here. All I did was follow their advice.

This mod allows you to use the Gnat Fuzz PCB to create an NPN Elka Dizzy Tone.

I wanted to share it here because it is a pretty simple mod to do with an existing PedalPCB board and because I didn't want to put this in the build reports because it isn't complete yet, but it does work! Credit to Music6000 for the build guide:

dizzy elk.jpg

After building the board I then took TheWinterSoldier's advice regarding gain and leakage:

The tonebender mk3 and all variants (buzzaround and dizzy tone) form a darlington pair in Q1 and Q2. You want lower gain and leakage. Something in the 50s and 60s gain wise and leakage under 100. The two multiply their gain and slam Q3 where the magic happens. Look for something between 70-110 hfe and leaks at least 150-200u. The leakage will help it bias properly.

I am using MP38A transistors for this. For Q1 I used 58 hFE and .097 leak. Q2 70 hFE and .125 leak. Q3 100 hFE and .172 leak (measured on a Peak DCA75). I didn't have any lower hFE with lower leakage for Q2 or else I would have tried those. I'm using an 1N34A diode, but plan on trying it out with some others that I have (GY 102 and D9V) to see how they sound, but I will have to wait until tomorrow until I can experiment more.

A quick gut shot. Watch out for flying saucers!

guts.jpg

Here is a sound clip. This is playing bass. I'm sorry for the terrible playing and recording, but my daughter was here watching Sesame Street. The kiddo gets really upset when I play bass/guitar and she can't strum on the strings so I was having to make faces at her to keep her from getting wild. I'm also sorry that you've gotta stare at the back of my fat calf lol.

I am pretty stoked with how this sounds already, though I definitely want to experiment some more. I am not really finding anything that it is lacking. It is mean and aggressive and nasty and spitty and I really love it. I think that a little more grind in the mids would be good, but I am using flatwounds here, so I think that a string change would would do more to change the tone in that direction.

https://photos.app.goo.gl/FLvCc1DtvUuDhRTJA
 
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Hell yeah brother! Good job. Wait till you hear it on guitar. Going into a marshall type amp it is nasty in the best kind of way. Love everything about it! Can't wait to see what you do with the enclosure.

Thanks man! And thank you for helping to pop my germanium fuzz cherry. The only other fuzz I've really used for any amount of time is the Woolly Mammoth clone I built nearly 10 years ago. It's kind of flat sounding to me, and the bass just falls out and I'd be getting lost in the cymbals. with it.

I am really surprised at how well the bass is preserved, I thought for sure that I would have to put a blend on the final version, but I don't think I'm going to. It's got a lot of chunk to it, and it gets this weird, slow "warble" kind of sound at some settings when sustaining a note that is kind of addictive. I only got to play with it for about an hour today, but tomorrow I will have a lot more time. I might even have to hook up the Mesa 400+ to see if I can't shake the house down with it.

I can see how you can become addicted to them, now.
 
The buzzaround is a variation of the tonebender mkIII and the dizzy to e is a variant of the buzzaround, so they are all pretty much the same circuit with value changes.
I recall reading that there was rumor that the Buzzaround was designed by Gary Hurst, but there are very few sources available to clarify the sorry. I got into the Buzzaround because of Robert Fripp. I wonder if he still has his 2 originals?…
 
Awesome job everyone! Clip sounds killer!! Reading the description before listening I was also expecting like you were that some bass would get lost - hell I’ve made pedals that loose some bottom end just on a guitar tuned a step and a half down. Adding to the wishlist!

Welcome to the cult of fuzz. No one but us will understand having 20 different fuzz pedals and going “no, no, they’re actually all very, very different”
 
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vero-p2p does a fantastic job of cataloguing all of the circuit variations of the extended tone bender family if you're curious


There are similar generic schematics and component spreadsheets for MKIIs MKIIIs etc etc.
 
Just a little update: I didn't have the time today that I expected, so my time in playing with subbing parts out was pretty limited. I was able to swap out a few different diodes though, with interesting results. The diode here plays a pretty large role in how this circuit sounds, moreso than I assumed it would, they all kind of brought a different character to the sound.

The diode I was using for the recording above was a 1N34A with a .348 VF. You can hear it above, but it is pretty aggressive sounding and has a good amount of gating, what I'd call spitty, and I really dig it. Overall I was happy with this sound, but wanted to try some others.

Next up was a GY102 with .217VF. This was my least favorite diode as it kind of neutered the pedal. I didn't play with it for very long but it pretty much dialed everything back. Not great.

And the one that I've left in for now is a D9V with a VF of .518. This seemed to heft up the sound a bit, actually. Everything got a bit more rounded out and the gating was not as severe. I really liked the way it sounded, but I also really liked the way that the 1N34A sounded and it will be very hard to choose. It might be cool to add a switch to go back and forth... who knows....?
 
Are those what I sent? :oops:
Yeah, they are. I had a bag of 10 of them and they all tested in the low 3's for VF, I pulled one out and brought it inside and tested at .217 so I assumed it's one of the ones you sent, since I didn't test them when I got them originally. But who knows, maybe I tested the ones I had after they'd been sitting in the sun all day or something.

Now that I've got a surplus of them they've been finding their way in to outgoing packages :)
 
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My apologies Joe. You'll soon have an assortment to try. I was going to go through some anyway to try out My Fluke and Chuck's test explanation.
No worries, it's not like I gave you any options when you asked! And just a warning, if you randomly send something to me I'm going to have reciprocate!

And the diodes will find their ways in to other projects, I'm sure. They just didn't happen to work great for this purpose. It is also possible they just had a bad connection, maybe. Those sockets are more or less useless after they've had components pulled out of them 3 or 4 times.
 
I went through a couple of D9Vs today and settled on one with a Vf of .456. The 1N34As were a bit too choppy for me and were cutting off the sustain, especially in the Famous Fender Dead Spot (TM).

In the video above you can hear the gating happening quite a lot towards the end of the video, though it is happening throughout as well.

This video below you can hear how the hard gating has backed way off and things flow through a bit more organically and there's no real note chopping happening, which I prefer on bass.

Just for reference, both of these videos were taken with an 04 Fender P bass with Lindy Fralin pickups and TI Jazz Flats.

https://photos.app.goo.gl/CJYuXHqjRckLuybS8
 
With that diode, it's all about the leakage. The circuit uses the diode's leakage to compensate for Q3's leakage. Check Q3's collector voltage with each diode. I don't have a magic number for collector voltage, but you know it when you hear it.
 
With that diode, it's all about the leakage. The circuit uses the diode's leakage to compensate for Q3's leakage. Check Q3's collector voltage with each diode. I don't have a magic number for collector voltage, but you know it when you hear it.
Thanks, Chuck, I'll check that out. It'll be good to know what I'm looking at and how to repeat it as well.
 
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