Tag Archive | Modding

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..:

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TTSH, Gate Booster mod

If you’re all new into how analog synthesizers can be controlled, you may first want to take a look at this Wiki article on CV/Gate for some jargon busting. Other than that, let’s dive right in.

Among the first electronics mod I wanted to add to my TTSH was the Gate Booster. To fully open the ADSR envelope generator of TTSH a +10VDC gate needs to be applied, thus in it’s stock config the envelope can’t be fired properly by using eg. any external gear that outputs a +5V gate. Add to the common CV/Gate specs, the TTSH envelope generator also needs a trigger signal (very short pulse) to work properly. This can be used to restart the envelope without disabling gate signal.

So what the Gate Booster does is, it converts low voltage level gate signals to higher voltage and generates the trigger signal from the gate input. The particular circuit board I bought for myself is this modified version (sold by Oshpark) with a socket for a Midimplant MIDI-to-CV/Gate converter board. Having MIDI (keyboard) input just made so much more sense than eg. building a CV keyboard like the Arp 3620.

Gate Booster board all populated.

Gate Booster board all populated..

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TTSH, speaker baffle mod

This was a quick “let’s see what happens” kind of mod for my TTSH.

In their stock config, the TTSH loudspeakers are supposed to be fastened to the circuit board, which is then fastened to the front plate. Handy approach eg. for having the electronics as a entirely separate, single ‘module’ for servicing etc. But problem with this is that it leaves a ~12mm gap between the driver and the front panel. Read More…

Odyssey, triumph over sliders

\:D/ Fatality, Arto, Win \:D/

That was of course pronounced with a Mortal Kombat-ish voice and hopefully in 8-bit sample depth ;). Yeah! I’ve been working on the sliders some hours every week and after about a month the “slider cleanup chores” are over! With a bit of practice (and once I built up the routine of cleaning a slider), it’d take me maybe something like 15-20 mins to clean up and assemble a single slider.

Repaired sliders on board B.

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Odyssey, VCF replacement

Came across ARP Tech’s Dual VCF module earlier this week and was instantly inspired. Whilst later Odyssey’s (models II & III) come with a 24dB/oct low pass filter (model 4075), the Whiteface is equipped with a 12dB/oct model (4023). Despite the latter is generally considered more musical, having a steeper cutoff slope naturally produces more classical “synth” (resonant?) sounds. Moreover, as ARP Tech’s module has both, having them both in a single synth would kick ass.. To say the least ;). So today, I decided to etch a PCB for the module!

Dual VCF board with few IC sockets installed

Luckily enough, the Odyssey service manual does provide instructions to upgrade model I synths for the 4075 module so installing the completed board should be a walk in the park. But first, I need to order some parts.

Not that there’s anything wrong with the filter module on my Odyssey, far from it. The dual cutoff mode just outweights maintaining the original parts at this very moment! Promise I’ll make the installation reversable ;)