My DIY distorsion

[Basstyra]

So, I had time to finish this !!


Pics :






Schematic :


So, there are 2 circuits in there.

*First, a clean boost, gain from unity to 10dB. It's the pot "Boost".

*Secondly, an OD stage. With hard clipping (1n4148 diodes). Switchable with the "OD/clean" switch. Controls : Gain, Volume. And "high cut" filter to reduce the treble gain.

So it can be used in clean boost, OD, or combining the two, to get a pretty harsh distorsion.

There are no filters except the "high cut" cap. So it's transparent, and allow, at low gain, some really, really great OD sounds.

The bad side is that it can quickly become unmusical.


Soundclip :
I used 2 basses, my Vigier Arpege and my girl's Fender Aerodyne.

I run bass => Potentia => Hartke B600 amp (60w) (Line Out) => PC. On the amp, the egaliser is almost neutral, I don't use the preamp on the Vigier, only the passive tone. 2 pickups, at a time I switch on bridge pickup alone.

First, Vigier alone. Without, and with trebles (tone control on the bass). Then, clean boost at unity gain, then boost. Pretty clean, isn't it ? The slight OD here is my PC soundcard who have hard times... If there is hiss, it's more the PC than the pedal, on the amp it's quite silent.
=> http://perso.wanadoo.fr/jumping-jack/autre/potentia/potentia01.mp3

Then, OD. I progressively higher the gain. Trebles cut on the bass. I switch "High Cut" at 1 minute 28,the change is obvious. At the end, max gain on OD + boost in front of that. There it goes really dirty...
=> http://perso.wanadoo.fr/jumping-jack/autre/potentia/potentia02.mp3

Then, with trebles on on the bass. If the trebles pass throught, it's du to the conception of the pedal, it's not a clean loop in parallel. I love that sound. Near 50 seconds, I really, really, really love.... At 54 seconds, I switch "High Cut", and run the gain higher. Savage....
=> http://perso.wanadoo.fr/jumping-jack/autre/potentia/potentia03.mp3

Then, with Fender Aerodyne.
Alone. Then clean boost (The same for the OD, it's my soundcard). Then overdrive. At 53 seconds, I'm on bridge pickup. At 1 minute 10 I switch "High Cut".

The Aerodyne is smoother, so the sound is less savage. I can control it better.
=> http://perso.wanadoo.fr/jumping-jack/autre/potentia/potentia04.mp3

To remember : it's transparent. So you have to control what you put in. At high gain, the trebles become horrible, beware... The "High Cut" switch allow to control that. In fact, I love the OD (low gain) sound without this filter, and in disto (high gain) with it. This OD tone is the one I have been searching for a long time... Precise, it beats all the guitars/basses OD I tested. Really all. The disto sound is less good, though. Harsch, a egaliser put after would be appreciated.

The most important thing may be that it's really dynamic. If you miss a note, it won't do it for you. You have to watch carrefully what you play, how you sound. This pedal definitively don't play for you, you have to make it sound. A compressor in front could help, but I prefer this sound straight.

It was a really good time, I learned tons of things... And having my own pedal on my pedalboard is just... just fantastic ! :hyper:

[Basstyra]

I'm a dumb...

Someone on talkbass noticed my last cap provided a cut off frequency at 159Hz with the volume pot. I tested with a larger cap, and yeah... the sound is really better.

I heating my iron to correct it...  :oops:  How could I forget about that...

So, the final schematic is that :

[Basstyra]

Eh !
It's been a while since I went here... I have kinda been confused by the change, and well, you know, time, girlfriend, work.... 

Anyway, I worked today. Here is the layout :



And here is how I set the circuit in the enclosure (by the way, I moved to Hammond enclosure, way better than many others....) :





I'll be back soon for my current project, a digitally-controled analog tremolo !

[Transmogrifox]

Thanks !  

What are the two 1k resistors for ?

This does relate to why your design sounds the way it does.  The input 1k resistor probably doesn't provide any audible effect.  (RE: Marty's Mr. Drive).  The purpose usually is to use the input parasitic capacitance in conjunction with the 1k resistor to create a low-pass roll-off to reject radio frequency noise.  AM radio in your distortion pedal can be very annoying.

The output 1k resistor is to limit the sink and source current through the diodes when they clip.  As you have your circuit, the distortion you hear is not as much a direct effect from the diodes clamping voltage as it is that the op amp is internally going into current-limit mode (a built-in protection to keep it from burning up in a short-circuit or low impedance output configuration such as you have).

If you put a resistor in to limit the current, you would probably hear a pretty big difference in the tone--but your battery would last longer

[Basstyra]

That makes sense. I'll try it one day.