Here’s a bass drum module I’ve been working on.
I wanted to make the best bass drum that I could fit on a stripboard and came up with this module. It’s based on Thomas Henry’s Bass++, with a bunch of improvements to allow for more control of the shape and tone.
The linked article has a demo video, schematic and stripboard layout.
Wow, impressive sounds out of that module! Really cool what you have done with relatively few components, which are also very standard components.
I am definately considering building this! It would be a great replacement for a simple 808 kick module I currently have in my case, which has limited modulation possibilities.
BTW: why did you install several transistors and resistors in sockets, as can be seen in the pictures?
Thanks! 
why did you install several transistors and resistors in sockets, as can be seen in the pictures?
The pair of transistors I put in sockets should be matched for the sake of temperature stability. Initially when I was building the module I just put in 2 random ones, and once I verified that everything was working I replaced them with a matched(-ish) pair. The resistor and capacitor are socketed because I needed to do a little bit of tweaking to find the most optimal values after building the module.
Interesting. I’ve had the Bass++ on my “do someday” list for a long time, though with mods. Including the separate envelopes for pitch and amplitude* and a minimalist wave shape control, as discussed in this thread.
I hadn’t considered exponential CV for the VCO and am not sure how useful I would find it.
I would likewise omit the master volume — an output attenuator, not something I generally want. I’d probably keep the shell volume and impact tone controls. Of course, I build Kosmo and have lots of real estate for knobs. And on PCB, so the constraints of stripboard aren’t relevant to me.
* By the way, the Barton Analog Drum (which I’ve built) has some distinct resemblances to the Bass++; it does lack the impact component and some of the controls, but it uses two envelopes.
I really dig the sound of this. Great job.
The exponential CV makes it possible to play basslines with the kick when the decay time is turned up. Also the exponential response makes the pitch envelope sound sharper.
In my breadboard prototype I felt that the impact tone control didn’t really do that much (It’s just a tiny square click that it’s shaping after all) so I got rid of it for panel space. I did also experiment with a different transient circuit with a bit of noise (link below), but didn’t really like how it sounded in the context of a kick.
I just noticed I had accidentally moved the “Board 1 bottom side” in the original stripboard layout causing the cuts to be misaligned.
This mistake has now been fixed (along with some other improvements to make the layout easier to read) and the layout in the post has been updated.