SoulSonicFX - Stage Overdrive - The Klon Killer!

soulsonic · Post by **soulsonic** » 11 Apr 2015, 19:56

Check it out... here is an overdrive I designed a few years ago. The intention was to come up with a thing that could function like the Klon, but sound much better (in my opinion). I built one of these for an old friend who has been gigging with it regularly for awhile now, and he loves it. Says that on top of being an excellent overdrive, it has the best sounding buffered out he's ever heard...
I'm probably going to start selling these things soon, but I thought I would share it here first.

With the Drive control set to minimum, it should be completely clean with a good amount of volume boost on tap. As you turn it up it gets distorted as you'd expect. The asymmetrical diodes give it a nice character. The Tone control is a simple treble cut kind of thing...nothing fancier is really necessary for this. The Fat switch gives a deeper low-end.
Might be a good idea to build it with a second footswitch to control the Boost function - that's something my friend suggested, and I agree...the ones I will sell will probably be done that way.

The bipolar supply gives the buffer alot of headroom, so you shouldn't have to worry about any boost pedals you might have in front of it causing it to distort when in bypass (unless maybe you have something crazy like the Titan boost...). I personally prefer to use the TC1044 for my charge pump chip - they don't seem to die nearly as easily as the MAX1044s, and the price is reasonable. All the values for components are common and easy to find... the 50k C taper for the Drive control is maybe a little oddball, but everyplace that sells pedal components seems to have that value, so you should have no trouble getting it from wherever.

Please try this out if you were disappointed by the Klon - I really think this is a much better sounding circuit and it's much easier to build. It also has much lower noise than that stupid ol' Klon circuit. I will draw a pcb layout when I have time... but in the meantime, please feel free to draw whatever layouts you want.

Intripped · Post by **Intripped** » 11 Apr 2015, 20:53

... Nooooooooooooooooo!
I thought i was finished with ODs
But with this presentation how could i not give it a try?
Well, THANK YOU!

soulsonic · Post by **soulsonic** » 12 Apr 2015, 00:16

Thanks guys! I hope some people try this one out. It shows how good sounding a simple circuit can sound.

tictac · Post by **tictac** » 12 Apr 2015, 02:00

Thanks for sharing!

I too was underwhelmed but the Klon circuit and have built a half a dozen or so different O.D. pedal that haven't been that satisfying either.....

Looking forward to trying something new...

About that tone control, so is it really wired correctly? The .22 cap is always bleeding signal to ground. Isn't that going to bleed away the high freq's?

Maybe that's the point, just checking.......

TT

soulsonic · Post by **soulsonic** » 12 Apr 2015, 05:10

tictac wrote: About that tone control, so is it really wired correctly? The .22 cap is always bleeding signal to ground. Isn't that going to bleed away the high freq's?

The value is only .022uF.... 22nF. The way this is wired, when treble is fully clockwise, it is a low-pass filter with a cutoff at about 7,2KHz...which is high enough that you're not really hearing much of a cut of the guitar's treble, since the amp's speakers aren't really reproducing anything above that anyway. When turned fully down, the cutoff is around 650Hz...enough that you hear the highs noticeably cut, but still not a steep filter at all. So yes, there is some filtering always going on that diminish the extreme high frequencies a bit, but it's very mild and pretty much just in the range of being able to tame the highs a bit if it sounds too shrill with your particular amp.

Groovenut · Post by **Groovenut** » 12 Apr 2015, 06:55

Hi Martin, great looking circuit! Any reason you chose the NE5534 over say a jfet or bjt input buffer? If space is no issue, I agree whats one more DIP8. Just curious if it was a tone thing or a drive thing. Also have you encountered any issues with the output being phase inverted from the input? Looks like at min gain you still have about 5x clean boost at the output which is plenty for drive purposes and no worries about clipping the final amplifier stage at the rails. Thanks so much for the contribution!

soulsonic · Post by **soulsonic** » 12 Apr 2015, 15:55

Groovenut wrote:Hi Martin, great looking circuit! Any reason you chose the NE5534 over say a jfet or bjt input buffer? If space is no issue, I agree whats one more DIP8. Just curious if it was a tone thing or a drive thing. Also have you encountered any issues with the output being phase inverted from the input? Looks like at min gain you still have about 5x clean boost at the output which is plenty for drive purposes and no worries about clipping the final amplifier stage at the rails. Thanks so much for the contribution!

I chose to use an opamp for the input buffer because of its ability to drive long cables and low-impedance loads better than just a single transistor - pretty much for the intention of giving an excellent buffered bypass. I chose the NE5534 after auditioning several different opamps and listening carefully to how much noise they produced in headphones - got the best noise performance with the 5534 (not surprisingly). I didn't try any crazy hi-fi opamps like the AD797, because there's really no point in using a $9 opamp for the input buffer in an OD, even though it might have a tiny bit lower noise.

I chose the LM833 just because it sounds nice in some other things, like the Crunchbox, so I tried it here and it sounded good.

My friend hasn't reported any issue regarding the polarity of the output. It's one of those things that doesn't even really come up unless you try running it in parallel with something. If that's a potential issue for you, I don't see why you couldn't just tack an inverting stage onto the output to flip it. You could use an NE5532 dual for the buffer opamp and use the second half for the output inverter. But, you'd also be adding to the noise by doing that - though not necessarily by alot. Also, if you're doing this with a separate parallel blender circuit, you could include the polarity reversing as part of that. There is at least one DIY blender I know of that includes that already.

Mbas974 · Post by **Mbas974** » 12 Apr 2015, 21:56

I believe the sound of a pedal is a combination of several things...
can you tell us something more on capacitor types that you used in your build ?

C8 C9 C10 are bipolar ?
C4 C7 are WIMA ?
and the rest SMF (except the ones in 1044 network) ?

tx

soulsonic · Post by **soulsonic** » 12 Apr 2015, 22:05

In my original build, C3 and C2 were metal film 5mm "box" caps. The other 1uF and 10uF were bipolar electrolytics. C4&7 are small ceramics...nicer C0G type ones. You could use polystyrene if you want to be fancy...

tictac · Post by **tictac** » 12 Apr 2015, 23:36

...The value is only .022uF.... 22nF......

Oh.... Duh! Sorry I was thinking it said 0.22uF!

Gotta look a little closer dude.....

Yea, that would actually round out the tone in a beneficial way....

Thanks for explaining

TT

brejna · Post by **brejna** » 13 Apr 2015, 12:54

Here is layout I did today and it can fit 1590B enclosure. Enjoy

soulsonic · Post by **soulsonic** » 13 Apr 2015, 13:42

Looks good!
One little thing I noticed, R11 should be 10k, not 1k

brejna · Post by **brejna** » 13 Apr 2015, 13:54

Here are docs with revisited BOM

roseblood11 · Post by **roseblood11** » 13 Apr 2015, 20:09

Looks good! I think I'll try this with an NE5532, with the second opamp used as a summing amp at the output, to mix clean and overdriven sounds.

Frank_NH · Post by **Frank_NH** » 13 Apr 2015, 20:36

Looks great. Any sound samples??

soulsonic · Post by **soulsonic** » 13 Apr 2015, 22:00

roseblood11 wrote:Looks good! I think I'll try this with an NE5532, with the second opamp used as a summing amp at the output, to mix clean and overdriven sounds.

OK, but be sure they are in phase with each other.

Frank_NH wrote:Looks great. Any sound samples??

I will ask my friend if he has any recordings of it. I don't have one of these in my possession anymore. I let him "borrow" it to "try" and he never gave it back...

Groovenut · Post by **Groovenut** » 14 Apr 2015, 16:18

So this is passing freqs above about 25Hz through the clipping diodes stage. Do you find the bass gets fuzzy? Granted the clipping doesnt happen until very late in the drive control sweep and because of the Vf there isn't a ton of clipping happening even at max (without the boost of course), but I was just curious as I haven't built it yet. Another alteration possiblilty would be to put a linear 10k pot in place of R11 as a Bass control. I have a 1590A layout I'm working on that I'll post when it's finished.

soulsonic · Post by **soulsonic** » 14 Apr 2015, 21:05

I didn't notice the bass being fuzzy at all. When the Boost is engaged, the cutoff is over 100Hz when the Drive control is at max.

jalmonsalmon · Post by **jalmonsalmon** » 15 Apr 2015, 16:01

I am kind of stuck on how to wire this one up.
Is the buffered bypass wired like a klone?

Groovenut · Post by **Groovenut** » 15 Apr 2015, 18:04

There are a few ways but I think the intended method via the schematic is to use one half of a DPDT as the switch shown on the schematic, and the other half to activate the LED. No need for the 68k bypass resistors that the Klon has though. I wired mine to also mute the output of the circuit in bypass as to avoid any bleedthrough of the OD circuit.