ProtoTypo PT5 – BUD666

While working on my ProtoTypo PT3 build I came to realize that actually just about any piece of Behringer audio gear would likely make a pretty neat candidate for hacking. I suppose that Behringer brands mostly as sort of entry-level hardware for the budget conscious. That is, anyone looking to get into audio production will often choose the least expensive entry point and grow up from there.

This reflects on Behringer resale value too, as people looking to “step up” want to off-load their (older generation) hardware to a market that’s constantly flooded by Behringer with the next generation gear (often carrying similar price tag with older gen). Why this is great for hacking is, it puts a ton of ‘source materials’ up for grabs at a very low price. Hacking a second-hand Behringer, say, to even see if it works usually doesn’t set you back much.. Even if you end up destroying the device in the process. Just remember to sort & recycle proper!

Take something like the 5€ DJ mixer (VMX100) that I hacked PT3 from: You’d be happy to get even half of new knobs for the same price (VMX100 has 13), add to that everything else like jacks, PSU etc! Looking at it from the electronics side, say, a basic opamp summing mixer is a basic opamp summing mixer regardless of whether it rolls off a Behringer or Focusrite production line. Using a basic functional block like this in a some other context then simply boils down to identifying it with the help of schematics or a some reverse-engineering.

Anyway TL;DR, I’m almost getting carried away so let’s cut to the chase!

Some months ago I spotted this second-hand Behringer HM300 guitar distortion pedal selling for 15€. I couldn’t help thinking “Well that’s a bargain, wonder if this would make a neat Eurorack module?”, and bought the pedal just to have a look. And so we end up with this build post!

I give you ProtoTypo PT5 aka BUD666 aka BUdget Distortion 666 :D

Why the 666? Well although I didn’t end up adding any extra features to the electronics, I still figured my hack has to be at least 2.22 times better than HM300!

ProtoTypo PT4 – Pairs

While working on my Monster Base (eurorack) case the thought occurred that maybe it would be nice to have some buses to route signals internally from one end of the case to the other, instead of running long patch cables (which can get messy in no time). And that’s this build, the ProtoTypo PT4 (models A and B) in all it’s simplicity.

For the panel artwork, the boring version would’ve been to use matching numbers on both panels. However I like my modular setup colorful, so I finished up the build with a twist on the Find The Pair / Memory game. Each of the bus pairs have similar images to label them:

PT4a panels

Eurorack Monster Base, design

Shortly after completing my TTSH build I started longing for some added functionality, as in having more function modules to patch sounds with. I then got into eurorack modular synthesizers, cobbled together a small desktop case (photo below) to house some modules in, and ran out of space shortly after. I have heard this is a very common story among modular synthesizer hobbyists ;)..

Oh well, looks like I’m about to design & build a bigger eurorack case!!

My first 3U 84hp eurorack skiff..

TTSH, miscellaneous mods

I started putting together a build post about the electronics side of my TTSH, but there really isn’t actually much to write about that. It’s a kit, and they just work straight-out-the-box when you learn even the details before starting and keep soldering sessions at reasonable lengths (don’t rush the build!).

That said, building mine was probably the first time ever in the ~20 years of electronics hobbies, that I managed to install a resistor of wrong value, in this case to VCO2 triangle-to-sine wave shaper circuit.. Live and learn; had some D’OH moments doing a part-by-part trace of the entire circuit :)

Anyway I thought I’d bundle some of the simple mods under this post. All these three were suggested by user Nordcore in the various TTSH build threads the Muffwiggler forum.

TTSH, spring reverb mods

Alritey let’s continue details of my TTSH with two spring reverb modifications. If you’re looking for other build / modification posts on the project, please visit the main page right here.

Opamp Upgrade

This modification is done to improve the noise floor of spring reverb, by upgrading the opamp in the output amplifier circuit (recovery amp). The mod was suggested by user Nordcore at Muffwiggler forum and looks like this:

TTSH reverb driver mod schematic by Nordcore.

I sort of failed with adding this mod in that I didn’t bother taking before and after audio recordings: So it’s rather impossible to say how much the noise floor was effectively reduced. On my TTSH the circuit was noisy before and is noisy after.. Yet I’d still say it’s better.

On to the build..:

The reverb driver circuit in its stock config