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

ProtoTypo PT2 – GRAM

One of the first modules I bought for this Eurorack 84HP utility skiff I’m putting together I was putting together to go with my TTSH, was a DIY kit of Ljunggren Audio‘s Roll Your Own (RYO) Penta sequencer. Upon building it I was delighted to notice that the PCB had marked solder locations on it, from which individual step gate output signals and a hold input (to pause the sequencer) can be sourced. Very modding friendly, just how I like it!

And that’s how Ljunggren Audio meant it too; they host a Penta modification page and also the Penta product thread at Muffwiggler forum has user ‘Stabilt’ (whom I assume to be among people behind RYO) suggesting a basic combined gate output circuit. I decided to use these two sources as a starting point for a gate output expander of my own, aka ProtoTypo PT2.

Basic gate output circuit by Stabilt @ Muffwiggler

If you’re looking for download links to pdf schematics, they’re at the end of this post. Let’s try it this way for a change, because why not ;)

TTSH, VCO sync mod

Heyyy I’m once again catching up my TTSH build documentation with yet another modification. Yayyyy!

This mod is based on Altitude909’s add-on board, which adds a Arp Odyssey style hard sync between oscillators. The build has been well-documented in this thread @ Muffwiggler, so please check there if you’re planning to add one to your TTSH (Hi Vlado!). I did a slightly alternate version for myself and on this post we’ll look at that instead! But first, here’s a video by Stephen Drake on what hard synced oscillators sound..: