DOD FX56B Super American Metal - any ideas for mods?

[LonePhantom]

Hey all, I got a DOD FX56B from an old school friend today, and I thought I would see if I could find any ideas for modifying it. I did a search and found a number of threads regarding a schematic, but all links were broken.

Does anybody have any ideas for modifications to the FX56B, or at least the schematic and a bit of an explanation of whats going on with the pedal?

Any help is greatly appreciated.

Cheers

[LonePhantom]

Also does anyone have any info on replacing the old 1/8" DC jack with a Boss style one? Do I just attach the yellow wire to the tip, and red to sleeve on the Boss style?

Cheers

[WGTP]

It appears that Dod made several pedals with the same basic layout, but changed the EQ by moding the values in the gyrators.  I had one I was messing with that I ultimately screwed up the traces on.  Anyway, I was trying to reduce the mids. 

http://www.freeinfosociety.com/electronics/schemview.php?id=2294

[LonePhantom]

Thanks. Looking at the schematic, are the pair of 1N34A germanium diodes the pair on the output side of the IC, and the trio of 1N4148 on the input side feeding to the distortion knob? Does that sound right?

Which parts were you playing around with to change the tone of the pedal?

Cheers

[ddpawel]

Ho Ho Ho.
Here comes Santa with bunch of mods.

-disconnect 0.015 near U2B and connect second 100k HIGH potentiometer from pin2 to pin3 of U2A
-disconnect 0.15 near U3A and connect 100k LOW potentiometer from pin2 to pin3 of U2A
-change 3.3k resistors near all gyrators to 1k resistor + 10 potentiometer - variable gyrator frequencies
-rotary switch changing diodes (all types possible)
-change 220k resistor near U1A to 22k + 500k Log pot - additional GAIN pot
-connect switch disabling 1N34A diodes (which make crossover distortion), or change to 1N695 less crossover, 1N4148 for more cross, remember more crossover (higher diode Forward Voltage VF) means in this effect lower volume
-change 47nf cap going to pin2 of U1A - more low and mud 100nF, more highs 22nF

Or mz favourite - changing all 1N4148 diodes to 1N4007, and opamps to CA3240E will give you nice stoner rock sound!)

Want more mods?

[LonePhantom]

Ho Ho Ho.
Here comes Santa with bunch of mods.

-disconnect 0.015 near U2B and connect second 100k HIGH potentiometer from pin2 to pin3 of U2A
-disconnect 0.15 near U3A and connect 100k LOW potentiometer from pin2 to pin3 of U2A
-change 3.3k resistors near all gyrators to 1k resistor + 10 potentiometer - variable gyrator frequencies
-rotary switch changing diodes (all types possible)
-change 220k resistor near U1A to 22k + 500k Log pot - additional GAIN pot
-connect switch disabling 1N34A diodes (which make crossover distortion), or change to 1N695 less crossover, 1N4148 for more cross, remember more crossover (higher diode Forward Voltage VF) means in this effect lower volume
-change 47nf cap going to pin2 of U1A - more low and mud 100nF, more highs 22nF

Or mz favourite - changing all 1N4148 diodes to 1N4007, and opamps to CA3240E will give you nice stoner rock sound!)

Want more mods?

Thanks for all that.

Are gyrators and transistors similar looking things? I haven't got the pedal in front of me right now.

What do the first two mods you listed do, and what do you mean by low and high potentiometer?

I'd love to get this sounding like some decent amp distortion with balanced mids, not too shrieky highs, and tight bass, and not so fizzy.

thanks heaps for the ideas. I look forward to playing with this over the Christmas break.

[ddpawel]

You can compare http://www.muzique.com/lab/gyrator.htm to http://www.freeinfosociety.com/electronics/schematics/audio/pictures/dodfx56.jpg
Now You will clearly see where gyrators are.

When You look at the schematics You will see three op-amp gyrators (opamp U2B, U3B, U3A). From U2B there  is a wire to 0.015uF capacitor and then to potentiometer (100k resistance marked as "HI"). You can do three separate controls: HI, Hi-second and LOW (this is in FX56B but not in FX56) by providing three potentiometers from 0.015, 0.01 and 0.15 capacitors the same way as one in the schematics.

[LonePhantom]

Ah so it's a bunch of components that creates a gyrator? Thanks for the info, I'll check it out and hae a look over the schematic tonight hopefully.

[draculax]

Ho Ho Ho.
Here comes Santa with bunch of mods.
...

Or mz favourite - changing all 1N4148 diodes to 1N4007, and opamps to CA3240E will give you nice stoner rock sound!)

Want more mods?

Hi.

Sorry if my question seems stupid, but, is it possible to mix differents opamps witout any trouble? I'v found 2 CA3240 (not E by the way) And I was wondering if i could mix it with one of the originals opamps?

Thanx.

[runmikeyrun]

if you google a chip's datasheet it will give you the pinout.  If the pinouts are the same, along with operating voltage, you can interchange them.

These are supposed to be amazing for bass guitar, let me know if you want to trade it for something... send me a PM and we'll talk.
.

[Rick899]

DDPAWEL:

I don't mean to hijack this thread but I have a  DOD FX 57 Hard Rock Distortion and a DOD FX55B Supra Distortion.  Do you have any mods for those?

[the3secondrule]

These are supposed to be amazing for bass guitar, let me know if you want to trade it for something... send me a PM and we'll talk.
.

I just got one - i'm gonna check it out on bass at band practise, and if i'm not into it, I'd possibly be keen to trade...

I'm in new zealand, just BTW

[runmikeyrun]

well the shipping might be more than it is to pick one up at guitar center or on ebay for $30... Plus I don't have much to trade right now, just a tremolo (in a VERY nice John Lyons wooden enclosure), an Atari Punk Simulator, and a valvecaster with an annoying hum (might be the wall wart though).

[the3secondrule]

well the shipping might be more than it is to pick one up at guitar center or on ebay for $30... Plus I don't have much to trade right now, just a tremolo (in a VERY nice John Lyons wooden enclosure), an Atari Punk Simulator, and a valvecaster with an annoying hum (might be the wall wart though).

Fair enough - actually, I've had a look under the hood, and compared it side by side with my boss hm2, and the fx56b is pretty damn close (and the only differences might be due to differing pot tapers - ie I can get the same sounds, just at different settings)
so this one is a keeper, for me...

[runmikeyrun]

well the shipping might be more than it is to pick one up at guitar center or on ebay for $30... Plus I don't have much to trade right now, just a tremolo (in a VERY nice John Lyons wooden enclosure), an Atari Punk Simulator, and a valvecaster with an annoying hum (might be the wall wart though).

Fair enough - actually, I've had a look under the hood, and compared it side by side with my boss hm2, and the fx56b is pretty damn close (and the only differences might be due to differing pot tapers - ie I can get the same sounds, just at different settings)
so this one is a keeper, for me...

no prob, I'll pick one up here cheap while they're still a secret!  lol.  Enjoy!

[runmikeyrun]

so i've got one of these on the way... finally... anyone have any new or different information about these?  A schematic perhaps?