Low Gain, neutral dist/OD

[Killthepopular]

I think What I'm hoping to find is a circuit that I can put in front of any clean pedal platform (clean amp, cab sim) and leave it on all the time, giving a little twist of the gain knob for more grit or zero grit. It doesn't have to be totally transparent, I just don't want it to cut loads of bass like so many dirt pedals seem designed to do. I mostly play on my own so I don't need the whole "cut through the mix" thing. My SD1 and DS1 sound good but they sound a bit thin. My Gypsy fuzz is pretty neutral but struggles to give me low gain (doesn't seem to clean up like fuzz faces do).
I want it to be pretty simple just because I'm a noob and want to try out a couple different circuits without buying loads of obscure parts.
So far the Dod 250 and the Red Llama look closest to what I want.

What about fuzz faces? Are those any good for what I'm looking for? I like their sound.

[Killthepopular]

I quite like Joe Davisson's EZ-250.  Only 15 parts (+ pots).  Links for: thread, schematic, my layout.

What's the advantage to using transistors instead of an opamp? More "Buttery"? Whatever that means...

[Mark Hammer]

A fellow brought over a Catalinbread Hyperpak for me to repair the other day.  It's a close relative of bother the Red Llama and Tube Sound Fuzz.  The drawing doesn't indicate, but the chip is a 4049UB.  As you can probably tell from the second stage feedback resistor, it's a little more intense than a Red Llama.  If it were mine, I'd drop R4 down from 1m.  VERY loud circuit, so you can afford to insert some form of passive tone control between the output and Volume pot.

I made myself an "Amber Alpaca" ( ), which is essentially a Red Llama/TSF, but with less gain.  The feedback resistor in stage 2 is 680k.  The feedback caps in each stage are 120pf, and the input caps for each stage are 100nf.  I also used a 1k current-limiting resistor for feeding the V+ pin on the chip.  At min gain it sounds very much like clean, but with a hint of coloration, and a little more lower-mids muscle.  Makes amp grind sound nice.

[Steben]

What about a FF with buffered input?

[Killthepopular]

What about a FF with buffered input?

What would the buffer do? Are fuzz faces a good choice for low gain stuff? I've never used one. Also I'm a bit wary of the whole transistor thing. Seems like FF designs tend to use weird transistors, especially germanium ones with the opposite power polarity, pnp I think they call it. I have seen ones that use 2n5088s though...

Fuzz faces have the lowest part count of any pedal I'm looking at and i love the sound. Guess I should definitely try it out.

[Fancy Lime]

One of the nice things about the Tube Sound Fuzz Family of Overdrives (there are a lot of variants, some quite a bit more complicated), is that you can easily get a wide range of sounds by changing just one or two parts. If you have a breadboard, you should breadboard this to make sure you can figure out your personal favorite configuration. If you don't have one, get one and then breadboard it. Seriously, this will be much more useful for finding your sound than anything we can tell you. But of course you need to know what components do what. So (I am referring to the part numbers in the Catalinbread schematic that Mark posted for convenience, the basic topology is the same for all of these circuits):

The thing consists of two CMOS inverter stages (the right-pointing triangles with the circle at the point). The first stage contains C1, R1, C2, R2, and the Gain pot. The second stage contains C4, C5, and R4. The Gain of each stage is defined by the ratio between the resistance in the feedback loop to the resistance in front of the stage. For the first stage that means (R2 + Gain pot)/R1. You can view capacitors as frequency dependent resistors to understand what they do in their respective positions. At high frequency, the resistance of a capacitor is low and at low frequency it is high. This phenomenon is called reactance (https://en.wikipedia.org/wiki/Electrical_reactance). That means that C1 is part of a high pass and C2 is part of a low pass for the first stage. C4 and C5 do the same for the second stage. The gain of the second stage is not very well defined because it relies on the output impedance of the first stage. You can reduce the second stage gain by adding a resistor in series just after C4. In fact, I like this type of circuit best with a gain of 1 on the second stage, so I would make that resistor the same value as R4 (and would make both 470k or so). I strongly suggest playing around with different values for the resistors and caps and see what happens. It's a lot of fun. I would start with the values for the Tube Sound Fuzz or the Red Llama and then change one part at a time. Make it ten times the value it was or a tenth and see what happens. When you get a feeling for cause and effect, you can slowly sneak toward your perfect setup.

BTW, you can use a CD4049 or a CD4069 chip for all of these with little difference. Use what is easier to get but beware that the size and pinout are different.

A Fuzz Face would be a bit of an odd choice for clean to slightly gritty stuff. The transition into clipping will be much harsher than with the CMOS designs and the clipping itself will be harder. Not saying that's a bad thing, I personally like it a lot. But from your description I would not expect that that is what you are looking for. But if you are starting to build pedals, you will find out soon enough that the answer to the question "should I build this one thing or that other thing?" is usually "I'll just build both!". So by all means: Try it out! For a first time FF build, I would go with a NPN design using 2N3904 or 2N2222 transistors. 2N5088 are much higher gain and therefore not exactly everybody's cup of tea in a FF.

Hope that helps,
Andy

[cab42]

What about the Barber LTD? David Barber shared  the schematic in this thread

https://www.diystompboxes.com/smfforum/index.php?topic=72917.0

I have it on my build list and I even think I ordered the parts at some point.

Anyway, I look forward to hear what you end up with.

[ElectricDruid]

what you describe is pretty much exactly Craig Anderton's Tube Sound Fuzz, aka the Way Huge Red Llama. Very natural and pleasing.

Yeah this looks like a really good suggestion. Lowest part count I've found so far, can do clean and  the tones sound good at low and high gain settings. And yeah, I'm no tube connoiseur but it sounds pretty tubey to me.
What's the sonic difference between those two versions of the same circuit?

Yeah, another +1 for TSF/Llama, an excellent idea. It's a good circuit to play with. Simple and lots of possibilities.

[GGBB]

Along the lines of the TSV - the "Jiggle" side of the Double-D from ROG.

[iainpunk]

this seems to be quite clean when turned down, but gets crisp and warm when pushed

Is it some sort of low gain fuzz?

not really a fuzz, more of an overdrive based on a design i found in an old text book from the tube era, it was designed to get maximum gain out of triodes, but jfet substitution works great

[Steben]

What about a FF with buffered input?

What would the buffer do? Are fuzz faces a good choice for low gain stuff? I've never used one. Also I'm a bit wary of the whole transistor thing. Seems like FF designs tend to use weird transistors, especially germanium ones with the opposite power polarity, pnp I think they call it. I have seen ones that use 2n5088s though...

Fuzz faces have the lowest part count of any pedal I'm looking at and i love the sound. Guess I should definitely try it out.

A buffer eliminates the treble cut off of a classic FF circuit just after a guitar. With a pot in series with the input you can g get real low gain settings. The typical wooly sound of a FF is very much linked to the treble cut.

https://www.youtube.com/watch?v=pkSAFNdcr2Q

This vid poster prefers the boost before the FF, because it sounds more transparent...

[Killthepopular]

The good ol' Electra distortion: http://fuzzcentral.ssguitar.com/schematics/electradistortion.gif
One of the most simple, yet amazingly good sounding little circuits. You might want to use two series pairs of Ge diodes instead of two singles and add a gain pot up front (wired like in the Jordan Bosstone: http://fuzzcentral.ssguitar.com/schematics/bosstoneschem.gif called "Attack" here). Or, simpler, just add a "softness" pot. See Arons mod tips: https://www.diystompboxes.com/cnews/mods.html #1 and #7, respectively. Still 10 parts or less.

I must have missed this post. I've looked into it. Found Joe Gore's premier guitar article about building a stompbox based around the electra. It sounds really good to me, like a less annoying version of the MXR Distortion +.

[Killthepopular]

I don't want to overload myself so I think I'll just go ahead with the following 3 circuits:
Dod 250. Red Llama. Electra Distortion.

I'll order the parts soon.

[Steben]

If you want simple, you could try Steby fuzz II:

https://www.diystompboxes.com/smfforum/index.php?topic=70765.0

You can even add diodes to ground as in an electra.

[roseblood11]

I don't want to overload myself so I think I'll just go ahead with the following 3 circuits:
Dod 250. Red Llama. Electra Distortion.

I'll order the parts soon.

From those three, the Llama might be the most neutral and natural sounding option. Instead of the DOD250, I'd suggest the Vox 1901, same circuit, but some different parts values. It needs a reverse logarithmic gain pot, just like the DOD - some layouts falsely show a log taper.

[Killthepopular]

Instead of the DOD250, I'd suggest the Vox 1901, same circuit, but some different parts values. It needs a reverse logarithmic gain pot, just like the DOD - some layouts falsely show a log taper.

This seems like a good shout. Similar to the DOD but warmer, deeper, less fizzy distortion, more saturated and tubey. I actually watched the JHS video on 70s opamp distortion pedals and thought the guyatone sounded better than the dod but it was a bit thin. Voicing is very different from the vox. Must be some part substitutions.
Hm, something about the vox reminds me of those old marshall pedals.



What the hell is 1u/16? Should i just regard that as 1uf?

What's the deal with d4, r7, d3? Is that bypass stuff? I can't see any of that on the tagboard effects layout. Presumably i skip that stuff if I'm gonna ultimately be making a generic true bypass pedal?

I'll probably use 1n34a for the diodes.

[Rob Strand]

This seems like a good shout. Similar to the DOD but warmer, deeper, less fizzy distortion, more saturated and tubey. I actually watched the JHS video on 70s opamp distortion pedals and thought the guyatone sounded better than the dod but it was a bit thin. Voicing is very different from the vox. Must be some part substitutions.
Hm, something about the vox reminds me of those old marshall pedals.

There's at least two versions of the DOD.  The earlier yellow ones (famous through Yngwie Malmsteen) have a 1nF input cap instead of a 10nF which is found in the grey ones.  That can thin-out the sound.  I don't mean the Yngwie Malmsteen pedal, as that is a re-issue of the yellow DOD overdrive.

At least one guyatone schematic I saw on line had a lot of errors (it should be the same as the VOX).

What the hell is 1u/16? Should i just regard that as 1uf?

1uF 16V

What's the deal with d4, r7, d3? Is that bypass stuff? I can't see any of that on the tagboard effects layout. Presumably i skip that stuff if I'm gonna ultimately be making a generic true bypass pedal?

It's just the LED circuit.  The zener makes the LED go out when the battery goes flat, a common trick.

FWIW,  for your pedal --> clean set-up I find all the MXR derivations a bit too harsh.   The pedals with the output filtering fair better.  TS9 is OK because it has the output filter but the midrange tone isn't as transparent as some like.  Some of the CMOS gate drives weren't bad.

[Killthepopular]

clean set-up I find all the MXR derivations a bit too harsh.   The pedals with the output filtering fair better. Some of the CMOS gate drives weren't bad.

So you think I would probably want to filter some of the high end on the electra and the vox? Are we talking like a fixed RC LPF in the 2-4k range or more like a passive tone control like on a rat? If i added something like that would I need to add some boost circuitry after it to restore any lost output level?

What's a CMOS gate drive? Do you mean like the red llama?

[cab42]

Instead of the DOD250, I'd suggest the Vox 1901, same circuit, but some different parts values. It needs a reverse logarithmic gain pot, just like the DOD - some layouts falsely show a log taper.

This seems like a good shout. Similar to the DOD but warmer, deeper, less fizzy distortion, more saturated and tubey. I actually watched the JHS video on 70s opamp distortion pedals and thought the guyatone sounded better than the dod but it was a bit thin. Voicing is very different from the vox. Must be some part substitutions.
Hm, something about the vox reminds me of those old marshall pedals.



What the hell is 1u/16? Should i just regard that as 1uf?

What's the deal with d4, r7, d3? Is that bypass stuff? I can't see any of that on the tagboard effects layout. Presumably i skip that stuff if I'm gonna ultimately be making a generic true bypass pedal?

I'll probably use 1n34a for the diodes.

I have a vero layout for that in the gallery.

https://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=3504&g2_serialNumber=3

It's for the Guyatone Zoom, but with a few different components it should work for the Vox.

[Killthepopular]

Is there a stripped down neutral sounding (not mid focussed) tube screamer based circuit schematic that I could check out?