October 31st, 2009

BYOC Overdrive 2

Here you can see the labeling explaining the toggle-switch settings. (click to enlarge)

Clones dream of electric overdrive.

This last week I’ve been busy building a brand new, dual boost/overdrive pedal for myself (as well as another pedal for a friend, which I may post about in the near future).  After fiddling around with modifying the DOD 250, I wanted to build an overdrive more from the ground up.

The DOD 250 was fun while it lasted, but it lacked the versatility I needed and didn’t push my Valve Jr quite the way I wanted it to. On top of that, it had been a while since I picked up the soldering iron. The results can be seen to the right.

The Build Your Own Clone (or BYOC for brevity’s sake) Overdrive 2 is an extremely versatile piece of gear. Not only is it a 2-in-1 Boost/Overdrive (both independently switchable), but because the pedal arrives un-assembled, you have the option of building it to several different specs. For instance, you could build the boost as mosfet transistor-based and the overdrive to classic 808 values, or the boost to the standard specs and the overdrive to mosfet. You also have the ability to modify each stage of the circuit, including the input/output buffers and clipping stage.

For further tweaking, the components used for clipping are selectable using an on-off-on toggle-switch (pairs of either silicon 1N914, mosfet transistors, or a diode lift). Three EQ options (full, normal or fat) are available as well.

I built the boost side using the mosfet option, and the overdrive to standard but with mosfet clipping. I’m currently auditioning the included Burr Brown opamp, but may swap it out for one of the other two supplied with the kit. The advantage of building a mosfet boost with the standard overdrive (and standard opamp), is that there is the option to run the pedal at 18v. This will give the signal more headroom, thereby allowing a richer and more driven effect to pass through.

So many wonderful knobs. (click to enlarge)

I have also wired the stomp switches so that the boost is first in the chain, feeding into the overdrive. Instead of simply making the overdrive louder when engaged, as is its original function, it now pushes a hotter signal through the drive, making for more clipping and a little bit meaner of a sound when I need it (as well as the volume increase). I had initially planned to make the order of the two sides of the pedal switchable via a toggle switch, but two things happened. One, I realized as I was building the pedal that I would almost exclusively (about 97% of the time, say) use the boost in front of the drive and two, I got lazy.

I’m particularly proud of the enclosure. I haven’t attempted etching a box since the EA tremolo I built over two years ago. I used the laser photo-paper method that can be found on several DIY sites, with Ferric Chloride as the etchant. I then painted in the details with model paint, giving it a light sanding after to bring the aluminum back out. I wasn’t too happy with the smaller details (such as the toggle-switch labels), so I picked up an old-school punch-labeler (which are surprisingly hard to find- tip: Michael’s) to add the final touches. With the knurled aluminum knobs from Smallbear, I think the aesthetic of the pedal really came together.

This pedal has become the cornerstone of my dirt section, and cannot wait to stack it with some other distortion. This afternoon I’m going to try a ProCo Rat after it in the effects chain to see how it modifies grittier distortion. I’m also curious to see how the DOD 250 performs both before and after it. Depending on the outcome, the 250 might stay on the board after all. Dirt is one of trickiest effects to nail down to taste, which may explain the plethora of available options on the market today (distortion being a fairly basic circuit to replicate might also be a contributing factor). The only thing to do is experiment.

Do yourself a favor and pick up a kit from the guys at Build Your Own Clone. Not only is it a great way to pass an afternoon or two, but when you’re done you’ll have one of the best overdrives on the market today. With a boost to boot.

by Preston | Posted in DIY | 2 Comments » | Tags: , ,


September 24th, 2009

VIDEO: DOD 250 w/ some bitchin’ mods

After making the 250 true bypass, I went ahead and did a few fidelity mods:

  1. I removed the stock 4558 dual op amp, which sounds like ass, and replaced it with a 1458. The 1458 is essential a dual version of the 741 op amp, which was the chip in the original 250 ODs.
  2. I removed the stock clipping diodes (I forget what they were) and replaced them with:
    • two 1N914 switching diodes
    • two 1N4004 rectifier diodes
    • no diodes

    All of which I put on a SPDT on-off-on switch. I forget which on-side is which pair of diodes, but the middle (off) is the no-diode setting.

So without further ado, here is the demo:

by Preston | Posted in DIY, PEDALS, VIDEO | No Comments » | Tags: , , , , ,


September 13th, 2009

DOD 250 Yellow Reissue Mods

This is the proper wiring for making the 250 a true bypass pedal. Note the wiring going into the pin connector.

Click to enlarge.

I bought the notoriously bland, famously on-the-edge-of-being-a-great-overdrive DOD 250 on the cheap recently. I picked it up with the sole intention of modding the circuitry. There are some great mods out there:

For instance, Analog Man has a page up giving a brief explanation of the circuit, and the differences between the reissue and the original pedal. It’s a good place to start for modding this pedal.

Also, a quick Google search will turn up half a dozen or so forum threads like this one, detailing people’s trial and errors with parts replacement.

I decided to start with true bypass.

One of my favorite things about this pedal is the use of a pin connector to easily separate the PCB from the actual hardware in the pedal. It’s a feature that will make it a hundred times easier to modify and test the circuit on a trial/error sort of basis. One snap of the connectors and I’ve got the circuit in my signal chain. An easy separation and I’ve got a stand-alone PCB to play with on the bench. Cool.

The signal path coming from/going to the white, female side of the connector is as follows:

From left to right, looking down on the opened enclosure.

Black: – output from circuit, coming from the second pin of the level pot.
White – ground
Green – positive
Grey -  output

A quick diagram to show the wiring from the pin connector to the jacks & switch: Read the rest of this entry »

by Preston | Posted in DIY, PEDALS | No Comments » | Tags: , , , ,















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