First Test of Finished TTSH Board

Now that the complete board is done, I could perform a first test. This covers VCO 1, 2 and 3, VCF, ADSR, AR, VCA, noise and sample&hold. At first all seemed to be working, but then I noticed two defects:

• One of the VCOs generated a way too high frequency compared to the others.
• The fine tuning of VCO 3 didn't have any effect.

It turned out that I had two bad soldering points: The 680pF capacitor on one of the VCO boards was loose on one end. And, the same was true for the 3.3MΩ resistor connected to the fine tuning slider of VCO 3. Correctly soldering both points luckily fixed this.

Here are two pictures of the main board functioning:

Mounting the front panel already gives a good feeling of how the TTSH will be:

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TTSH Main Board Done

Finally the main board is ready. I have now installed all switches, sliders and jacks:

Before soldering everything I had mounted the front panel, to assure that everything was correctly aligned.

Following are a few detail pictures:

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TTSH LED Drivers, Jumpers and Headers Done

Today I've mounted the last electronic parts, the LED drivers. Also the 7 jumpers for these and some headers to later connect the peripherals to. The next step will be the switches, sliders and jacks.

TTSH Sample and Hold, Internal Clock, Analog Switch and Amplifiers Done

Earlier this week I've finished the Sample&Hold, Internal Clock and Analog Switch part:

The 1.5µF electrolytic capacitor (bright blue) at the bottom wasn't available with Mouser, but luckily I had a few of these from the past. Then I had made a little mistake: Soldered in a 10Ω resistor instead of a 100Ω one (near the 1.5µF capacitor, in vertical position). I only noticed when a 10Ω resistor was missing for the next section, the amplifiers part. Removing the vertically positioned resistor and putting back in the correct one was not that easy.

[Update] Then only later I detected that the analog switch was not working correctly. Channel A was always on. I had overlooked to solder one side of a 3.3MΩ resistor that controls one of the 2N5172 transistors, which actually can be clearly seen in the top-left corner of the above image. The fix was thus easy, luckily.

And thus also the amplifiers part was finished:

TTSH Mixer, Reverb, Noise and Voltage Processors Done

Earlier already I finished the mixer and reverb section:

And today I also finished the noise and voltage processors sections:

Note that i have not inserted the "noise transistor" yet. I want to insert a socket here to allow some experimenting and finding the best fitting transistor here. I'll also get a TL071 instead of a LM301 for the voltage processor, as indicated on the board.

TTSH Preamplifier, Envelope Follower and Ring Modulator Done

Yesterday I have also finished the section with preamplifier, envelope follower and ring modulator:

TTSH VCA Done

The next section I've done is the VCA:

TTSH ADSR and AR Done and Tested

Next to the VCF section is the ADSR and AR section, which I've finished now, too:

Powering up again, connecting the according ADSR and AR outputs to my oscilloscope and pushing the button shows the following waveforms (after some fine-tuning of the sliders):

This looks pretty good, I think.

TTSH VCOs and VCF Done and Tested

Now that I have all components available, I was able to build up the three VCOs, attaching the small boards with the according connectors to the main board:

Meanwhile I had also finished the VCF part. As you can see I'm not using the built-in power unit, but will be using my own external power supply:

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The TTSH Story Continues - All Components Available

More than one month has passed, but finally I have managed to get all the required components. I was still missing the 2N4125 transistors for the small VCO boards and 4 ceramic capacitors of 5pF. As replacement for latter I got some 5.1pF capacitors through some relatives in the Netherlands. The 2N4125 transistors I've found when looking for the reverb tank. Banzai Music in Berlin, Germany, who offers such reverb tanks, also sells electronic components and interestingly they also have the 2N4125 available.

Having the transistors and capacitors, I was able to finalize the three small VCO boards. Once done I've cut them apart:

And here's the reverb tank:

The other missing parts were the Peerless loudspeakers, which I've found at Straßacker Lautsprechershop in Karlsruhe, Germany: