OmniDrive Build Report

[auden100]

Started this build a couple months back. My first pedal. Made for my bass player friend. He said he liked knobs, and as this was gift, I put in as many as I could fit into the design.

Original Schematic - http://www.geofex.com/PCB_layouts/Layouts/omnidrv.pdf

Mods:
- Doubled caps used for tone shaping to apply to bass guitar frequencies.
- Used AMZ's BMP Tone-Body control (AMZ Presence Contro - http://www.muzique.com/lab/tone3.html)
- Made the LP filter section adjustable with a 500KB dual pot replacing R6 and R7.
- Used a 2p3t switch to make the LP apply to either the clean, dirty, or both signals.
- Inserted a 6-way diode selector switch.
- Second footswitch for octave bypass.
- extra 150pF cap parallel to Gain to roll off some fizzy highs.
- 500K pot replacement for Blend, as I wanted a full pass from one to the other, and the 50K wasn't doing it. A 500K was probably overkill, but that's what I had.







Controls -
Top Row - Tone, Volume, Blend.
Middle Row - Mode, Diode Select, LP Mode, Treble Boost.
Bottom Row - Body, Gain, LP Filter
One extra switch next to AC jack to switch the gain settings.

The power jack in the back doesn't seem to hold the cord too well. Also, the Gain knob didn't specify logorithmic or linear, so I tried linear. Turned out to be the wrong choice. Really should've used a log pot here. Ended up having to add an extra switch on the back that puts in a parallel resistor just so I had some easily accessible lighter overdrive. I also had a little trouble with a couple wires being too close and causing noise. Easily fixed though.

All in all, I really like the sound and range of this pedal. Not the perfect OD, but the ability to shape the tone both before and after the gain stage really has a nice effect on its sound.

Thanks to the many members of this forum for answering my noob questions, and providing ideas. My bass player friend is grateful as well.

[Paul Marossy]

Nice work. I've wanted to build one of those when I first started building stuff a long time ago, but I never did.

[dmc777]

Wow! That's your first build? My first build, besides mods, is a true bypass blender pedal and I still can't get it to work! Is this pedal more of and Od or distortion?

[Paul Marossy]

Is this pedal more of and Od or distortion?

Check out this page here: http://www.hollis.co.uk/john/circuits.html

From that page:

"OmniDrive
This is a versatile distortion pedal. Think of it as analogue modelling, using analogue circuitry to model a wide range of analogue distortion devices. It includes the main elements found in the majority of distortion boxes. The unit comprises four sections:

1. A pre-amplifier with switchable treble boost.
2. A switchable low pass filter.
3. A switchable full wave rectifier for octave-up effects.
4. A clipping stage with variable gain and two clipping modes.

These stages are combined with level and tone controls to allow emulation of most of the multi-stage overdrive and fuzz units. The rotary controls are drive, tone, blend and volume. The switches are treble boost, low-pass filter, octave up and distortion mode. I have also added an optional scoop switch to the tone control circuit. This cuts the mid-range and should be popular with death metal noise vandals."

[deadastronaut]

i would love to hear this..i etched a board for it long ago but went down the dr boogie route....

...but would like to hear it in action...any clips?

[auden100]

Thanks, folks. 

I've really enjoyed the sound of it so far. It is pretty versatile, just as described. Many settings are uninspiring, but being able to adjust the EQ before the gain stage as well as after imho is the handiest method by which it produces usable tones.

I'll post some clips if I can. I gave it as a gift, so my access is relatively limited.

Should have mentioned this before, but I also included the suggestions by Mark on how to boost the Octave effect. He mentioned here: http://www.diystompboxes.com/smfforum/index.php?topic=42755.0
Those really helped out.

I had read a couple of places, as well, that there wasn't much difference between the Mode settings for the diodes. IIRC I found this to be somewhat dependent on which diodes I was using.

[Taylor]

That's very impressive for a first build. Excellent job. May I ask, why the on/off washer thing on one switch but not the other?

[auden100]

Thanks, Taylor. I guess I just wanted to highlight the fact that the blue side is the entire effect bypass, while the orange side just affects the octave connection within in the effect. Not that it's necessary, but I had that little piece and thought it looked cool. A little asymmetry never did anyone harm.

[karter2000]

Started this build a couple months back. My first pedal. Made for my bass player friend. He said he liked knobs, and as this was gift, I put in as many as I could fit into the design.

Original Schematic - http://www.geofex.com/PCB_layouts/Layouts/omnidrv.pdf

Mods:
- Doubled caps used for tone shaping to apply to bass guitar frequencies.
- Used AMZ's BMP Tone-Body control (AMZ Presence Contro - http://www.muzique.com/lab/tone3.html)
- Made the LP filter section adjustable with a 500KB dual pot replacing R6 and R7.
- Used a 2p3t switch to make the LP apply to either the clean, dirty, or both signals.
- Inserted a 6-way diode selector switch.
- Second footswitch for octave bypass.
- extra 150pF cap parallel to Gain to roll off some fizzy highs.
- 500K pot replacement for Blend, as I wanted a full pass from one to the other, and the 50K wasn't doing it. A 500K was probably overkill, but that's what I had.

Sorry for the zombie thread bump, but I just built an OmniDrive, and I'd like to apply the bass changes you made.  My questions are:

1. What values/what caps did you change for use with bass guitar?
2. How did you wire the 2p3t switch for the LP filter?

Thanks!