The Mighty 250!
This build is based on the 1977 gray DOD 250. It uses the LM741 op amp. As with my Aion Boss OD-1 build, this one went smoothly, except that I installed the 4.7 uf electrolytic cap in C5 incorrectly and it didn’t work at first. Once I got it oriented correctly, it fired up perfectly. Be mindful that there are three solder pads for C5 and you need to make sure you use the correct ones and have the polarity right if using an electrolytic cap there. The three toggle switches are board-mounted while the pots are off board. I used a BB-sized enclosure so that I could include a battery and have the ¼ inch jacks and DC jack all mounted on the back.
The clipping switch toggles from stock to a Bluesbreaker stacked diode configuration with the diodes lifted in the center. Stock has more gain and less volume while the stacked arrangement is the opposite. So far, I prefer stock, but like that I have the extra option. The softness trimmer is awesome for fine tuning purposes since this circuit can get pretty bright with the gain knob at or near maximum. I’m still experimenting with the comp and treble switches. They do give you some different tones and textures.
Even without the added toggle switches, this is still a very versatile circuit, especially given it only has two controls. It can be used as a booster all the way up to heavy Randy Rhodes style distortion. That said, why not build it with the switches? The pads are already included on the PCB. Thanks to Kevin for the very well documented and easy to follow project instructions.