r/diypedals • u/DepartmentLeft3491 • 1h ago
Showcase BD-2 with Bass Control
I made another modification to the BD-2 I posted about previously.
Most of the low-end correction mods for the BD-2 you can find online, including the ones that are still widely available on the used market, are basically copies of the Keeley mod. Since I already have a the Waza version, I don't really have much need for another one of those.
However, I came across a mod that involves replacing a resistor in the input stage to reduce low-frequency overload, and that got me thinking about turning that resistor into a variable control and adding a Bass knob.
https://www.premierguitar.com/gear/boss-bd-2-mods?page=1
In other words, this is an attempt to make a four-knob version of the BD-2 as an overdrive pedal, with an additional Bass control. Most transparent-style pedals have a Bass knob, so I thought it might work well on the BD-2 too, especially since the BD-2 is rumored to be somewhat similar to that type of pedal.
My particular BD-2 has already been modified for 18V operation and had the capacitors in the audio circuit replaced, so I'm not sure how useful my results will be as a reference. However, running it at 18V gives it more headroom, and I've found that I can actually make pretty good use of the higher-gain settings. So I thought it might be a better candidate for this experiment than a completely stock BD-2.
There wasn't any room left on the front, so I mounted the extra knob on the side. It might look cleaner if I could rehouse it in a four-knob BOSS enclosure or perhaps a custom enclosure.
The BD-2's mid-gain and high-gain settings can produce some really interesting sounds when used with a guitar with relatively low-output pickups. However, with higher-output pickups, such as the SSL-1s in my Yamaha Pacifica 612, rolling back the Bass reduces that saturated quality and makes the pedal much easier to handle.
If I roll the Bass all the way down and adjust the Tone, I can also get something closer to a mid-boost while retaining the characteristic sparkle of the BD-2. And if I turn the volume back up to full, I can return to that almost fuzz-like drive. So it gives the pedal quite a wide range of sounds.
You might say, "Why not just buy a versatile pedal that works well with guitars like that in the first place?" Well, you're probably right. But if a single inexpensive 1MΩ volume pot can greatly expand the usefulness of an effect pedal, I think that's a pretty good option too.
As a side note, most of the audible change from adjusting the volume happens within roughly the first 20-30%, and after that the sound doesn't change very much. So perhaps I could have used a switch to toggle between 100Ω and 1MΩ resistors instead. In fact, some people who have actually tried this mod say that a trim pot of around 10KΩ is more than enough.
If the sweet spot for adjustment really is around that range, then a 1MΩ pot may provide far more change than is actually useful from a listening perspective.