ProtoTypo PT3a – BUM

Time for the next ProtoTypo build! This is a quick one I’ve been working on during the past week, and for a change I thought I’ll just get the build documentation out of the way while I’m in the zone (noooot!).

It’s a Behringer VMX 100 Dj Mixer. Photo by internet.

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..:

LED mods for Arp 1601 clone

Still time for a quick one before it’s ‘BYE BYE 2016’! :)

While building my TTSH I also got myself a DIY kit of a Arp 1601 sequencer clone. The build itself was so straightforward that I didn’t see the point in blogging the details. However I made some LED mods to it and thought maybe this would be of interest to owners of this device. So if you ended up here looking to change the color of LEDs on your Arp 1601 clone, look no further! If you’re in a hurry, check the summary section at the end of this post.

While you can also find my posts related to the mod at Muffwiggler (Muff) forum, I thought my blog here is a more compact way to present the information. For one, since forum threads at Muff are created by product / project, there’s a number of discussions going on at the same time (esp. if a DIY build). So a thread can become convoluted. Second, threads which span years (or multiple production runs of a kit) can become l-o-n-g, adding to the ‘needle in a haystack’ effect. Third, if you’re not logged in the board system won’t show post attachments or the like. So it can be quite the dig looking for information you need.

But don’t get me wrong, I love the Muffwiggler board and a lot of highly skilled people dwell there. It’s just that often the format isn’t good for finding information that you need instantly.

Well maybe my ramblings aren’t either, but let’s not follow that tangent! :D

My finished 1601 build

ProtoTypo PT1 – WOTI

Yay it’s a firstie, my soft landing to the world of Eurorack: A DIY version of Xaoc Devices‘ POTI expander for Batumi (a quad LFO module). “What is ProtoTypo?” you might wonder? Then check my previous post.

The Build

Simple one yeah: three toggle switches mounted on a 3HP euro panel and connected to a 6-pin ribbon cable. Haven’t done anything this straightforward in ages, but still it’s a good crash course into eurorack mechanical specs and the like. As for Poti, there’s a good set of pictures of it at the Schneidersladen webshop, from which it’s easy to interpret wire connections.

Heatshrink stress relief for the cable solder joint

Here’s a good generic build tip: As switches are connected to Batumi using flat cable (see photo below), it’s very much recommended to add some heat shrink tubing to cover solder joints. This is because flat cable is thin and flexible, and soldering any of its wires creates a sharp stiff-to-flexible transition point. If the cable is moved or flexed repeatedly then the wires will easily break off at this spot. So adding heat shrink over the joint will distribute the weight of cable to a wider area and thus lessen the risk of broken wires.

Cabling overview

…and how it connects to Batumi.

I have quite a neat leftover piece of this 4cm thick oak kitchen tabletop (from Ikea), so I figured I might just as well use some for building Euro panels. After all 4cm = 8HP (in Euro spec 1HP = 5.08mm / 1/5″) so it’s a perfect match size-wise. Once the oak is cut to 4HP slices 2mm thick, it’s very easy to trim down to required width. Simply running a sharp carpet knife along a ruler repeatedly will eventually create a straight groove deep enough to slice the thin wood panel in half. Minimal sanding required, yay \o/

So with panel cut & drilled, I treated it with white wood stain and then designed and printed a panel decal to a leftover Lazertran sheet (from my x0xb0x build btw!).

Now I have no clue if ‘Poti’ means anything, but I’m a big fan of abbreviations so I chose to call this build ‘WOTI’. That’s short for Wooden Output Toggle Interface. You know, oak panel and all! ;)

The finished module, fancy innit?!

So there it is, ProtoTypo PT1. Of course I added it to Modulargrid.net too :). You can download the panel decal here for your own build. Poti manual is available from Xaoc Devices’ website.

The design of this module could be squeezed to 2HP too, provided that the switches were of sub-miniature type and/or oriented vertically. However I wanted a design to match Poti, so it was 3HP for me.

That’s that. Next up a ProtoTypo build with even some electronics in it!