SynthCube FuzzBass TTSH Build Manual
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SynthCube FuzzBass TTSH Build Manual

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TTSH Version 4 Build Guide
Covering Synthcube's TTSH V4 release
Version 1.10 April 2020
By
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Summary of Contents for SynthCube FuzzBass TTSH

  • Page 1 TTSH Version 4 Build Guide Covering Synthcube’s TTSH V4 release Version 1.10 April 2020...

  • Page 2: Table Of Contents

    Construction – Main Board Finishing Up ....................25 Check out and Calibration........................27 Common Build Issues and Tips ....................... 29 Fuzzbass TTSH VCO/VCF Pitch Calibration Routine ................. 30 Putting It All Together ........................... 35 Modification: Add Power Taps for Future Mods ..................37 Modification: AC Coupling on the VCF Audio Mixer Inputs ..............

  • Page 3: About This Guide

    If you purchased the Synthcube kit, you received quantity 8 50mm M3 M-F nylon standoffs. These are intended as stilts to raise the main board from your bench so through hole components can be stuffed.

  • Page 4: Transistor Coupling And Matching

    ¼ inch Heat shrink tubing (can be subbed with cable ties) • Cutters • #2 Phillips driver • Nut drivers 5/16 and 1/2 inch. (Synthcube kit includes hex nuts for the 3.5mm jacks) • 2.5M hex key • Fine tip needle nosed pliers •...
  • Page 5 Ziff Socket. https://dragonflyalley.com/synth/images/TransistorMatching/ianFritz-transmat0011_144.pdf The Synthcube kit contains the exact number of transistors needed to complete the build. It may or may not yield the required number of matched pairs. The Synthcube kit used in preparation of this document did yield all the required matches.

  • Page 6: Part Substitution

    All resistors are ¼ watt through hole types and for the sake of consistency are stated as metal foil 1%. Synthcube may pack a few in the kits that are 5%, or 1/8 watt, and this is fine. It is assumed that most of the resistors used in the ARP 2600 were 5% carbon composition types, with probably a small number either higher precision, or hand selected.

  • Page 7: Standard Substitutions

    those on hand. Any type listed as film should not be subbed with a ceramic cap of any rating. Generally, any capacitor can be subbed with a nearby standard value. For instance, 4.7p caps are fine for 5p locations. Generally (and where available values overlap): •...

  • Page 8: Quirks

    • The 2N3954 dual JFET footprint in the VCO2 section (still) has reversed pins 5 and 6. Instructions are included below to correct for this during construction. • On the power sub-board, there are a couple of test pads marked +15.00 and -15.00, respectively.

  • Page 9: Planning For Modifications

    If you purchased the Synthcube kit, you will want to report any missing parts as soon as possible.
  • Page 10 a 3.5mm Jack, the 6.3mm TRS jack, one of the sliders, and an M3 screw, check each hole and slider groove to make sure there is clearance for the parts. Check the 17 M3 screw hole punches to make sure there is adequate clearance for the screws. Where issues are found, file out the openings to resolve this.
  • Page 11 Four 1uF box film capacitors are recommended, and these are included in the Synthcube BOM and full parts kit. Figure 2 - Locations for trace cuts to implement AC Coupling for VCF Audio Mixer 7.
  • Page 12 installing the bulk of through hole components on the main PCB. You will also want a roll of masking or painter’s tape on hand to use the backer board. 8. Build the 4027-1 VCO cores. Start with the 0805 SMD capacitors on the bottom side of the boards. This can be done with a standard soldering iron, but be sure to dial the temperature down to 600f/315c for the caps.
  • Page 13 improve heat transfer. The time to do this depends on the heat of your iron, and the size of the tip. Once you see the solder flow across the tab, keep the heat on the work for at least ten seconds longer.
  • Page 14 Table 3 – PSU BOM 10. Build the 4012 VCF Core. There are six matched transistor pairs (5x 2N3904 and 1x 2N3906). Additionally, there is one thermally coupled NPN-PNP pair. If possible, try to thermally couple the 1k87 tempco resistor to the NPN-PNP pair. Doing this will mean the tempco’s leads will traverse some other resistors.
  • Page 15 Active Components 1N4148 100k LM1458 196k LM3900N 220k 2N3904 270k 2N3906 2N5087 Trimmers 100k (Piher) Table 5 - 4072 VCF Core BOM 12. If you plan to install a Gate Booster, build the PCB now. The Fuzzbass Gate Booster is silkscreened with reference designators for parts (ex: R1).

  • Page 16: Construction - Main Board Phase 1

    Wire Housing .1 x2 IDC Wire Housing .1 x3 IDC Friction Lock headers .1 x 2 Friction Lock headers .1 x 3 Table 6 - Fuzzbass Gate Booster BOM CONSTRUCTION – MAIN BOARD PHASE 1 This phase will affect a bulk installation of parts that can be immersed in a water bath. If you are using organic flux solder, phase 1 can be completed with it before washing the board and proceeding to completion.
  • Page 17 VCO1 VCO2 VCO3 Noise S&H Total 30k1 40k2 45k3 54k9 61k9 68k1 84k5 100k 120k 121k 150k 180k 182k 196k 220k 270k 470k 680k 1N4148 8 Table 7 Main Phase 1 (resistors and diodes) 3. Place your cardboard backer board over the work, and using tape, secure the edges. While supporting the cardboard in the middle with one hand, carefully flip the work over and place it down flat on your work surface, pressing down across it to eliminate any gaps between resistor bodies and the main board.
  • Page 18 If you purchased the Synthcube full kit, the 10uF electrolytic capacitors included have a lower profile than other polarized caps. They can be worked in with this batch.
  • Page 19 Set aside the MJE172 and MJE182 transistors for now – as they stand much higher from the board. Note that in the first batch of V4 (Synthcube) boards, the footprint of the 2N3954 in the VCO2 section has pins 5 and 6 reversed. If you are building this main board, be sure to form those pins on the 2N3954 to fix that bug.
  • Page 20 VCO1 VCO2 VCO3 Noise S&H Total 2N3904 2N3906 2N3954 2N3958 2N4392 2N4870 2N5172 2N5460 100n(film) Table 10 Main Phase 1 - small signal transistors (100n are film capacitors) • 2N3904 Matched pairs: RMx2, VCAx1. • 2N3906 Matched pairs: RMx2, VCAx2 •...

  • Page 21: Construction - Main Board Phase 2

    16. In you intend to install the four optional film capacitors to AC couple four of the inputs of the audio mixer in the VCF, install these caps now. Remember that for them to function, traces running under them must be cut. 17.
  • Page 22 soldered to the main board, and the male section is soldered to the sub board. Double check this before soldering – a mistake here can lead to pain later. Without going into detail, the idea is to set the sub board on the headers, and immobilize it (cable ties for the 4027-1s, and 12mm spacers with screws for the VCF cores).
  • Page 23 Figure 6 - Courtesy of DSL-Man 11. Replace the stilts on the front side of the board with 12mm hex spacers (4) such that the female side of the spacer faces up. Add a fifth spacer in the center hole at the top edge of the board and secure this with an M3 nut on the back of the board.
  • Page 24 • (left) Input on 1 Voltage Processor (norm: KBD CV) • Noise Generator Output • Sample and Hold Output • Sample and Hold External Clock In (norm: Internal Clock) • Electronic Switch “B” • Envelope Generators Trigger (usually norm: Gate Booster Trigger Out) •...

  • Page 25: Construction - Main Board Finishing Up

    13. Once you have the VCF Output jack fit, place the other jacks with conflicts as per the list above, forming the frames of the jacks to avoid causing short circuits with signal traces. Then, place all remaining 3.5mm jacks, the momentary push switch in the EG section, and all six slide switches. Use a caliper to set the elevation of the mounting nut on the push switch to 12mm from the base.
  • Page 26 b. Wire up a temporary connector for DC power. Cut the +12V wire to 12 inches / 32 mm, and the GND wire to 24 inches / 64mm (reasons will become clear later). Terminate to the two-way, .156 wire housing (as indicated on PCB), and solder the barrel connector (as shown below), for the external AC adaptor to the DC-DC converter.

  • Page 27: Check Out And Calibration

    Positive Probe Negative Probe Resistance “0” +15.00 “0” “0” “0” -15.00 +15.00 -15.00 Table 15 - Checking for Shorts b. Repeat the resistance checks on the DC-DC converter board outputs. c. Set the DMM in voltage mode, connect the negative probe to the center “0” output pin, and the positive probe to the pin (not the test point) marked +15.00.
  • Page 28 The first thing to check when you power up is the expected behavior of the VCO cores. Any problems here need to be worked out before proceeding to other checkouts. Set each VCO to base operating mode for calibration: All modulation sources minimized VCO in KBD mode 0V or nothing connected to the KBD CV bus Coarse Frequency control minimized...

  • Page 29: Common Build Issues And Tips

    Note1: If AC coupling has been added to the four inputs on the VCF audio mixer, the observation at step 6.1 will a range of wave shapes moving around the 0V line; there will be 0V, not 5V, DC offset. Note2: Bypass the Freq Cal and Volts per Octave steps if using the Fuzzbass calibration.

  • Page 30: Fuzzbass Ttsh Vco/Vcf Pitch Calibration Routine

    LED dimmer, or it may be calibration of the Internal Clock. FUZZBASS TTSH VCO/VCF PITCH CALIBRATION ROUTINE The point of this alternate calibration routine is to allow the player to set the VCO controls visually to baseline, play A4 (MIDI note 69), to produce 440hz out of the VCO or VCF.
  • Page 31 You can perform these adjustments yourself if you have adequate measurement devices. It is also possible to make these adjustments by ear, if you have some type of minimal standard to work with, such as a tuning fork, a reference standard oscillator, or good ears. Purer tones such as sine or triangle work best for adjustments by ear.
  • Page 32 First, review the MIDImplant documentation. Information documented there is not repeated here. The gate voltage of the Synthcube Edition MIDImplant is fixed at +5V. This means that a Gatebooster is required when using this version. The implant’s gate default functionality is ideal for the TTSH, and no changes are recommended: •...
  • Page 33 Any setting expressed here in a decimal number must be converted to a hexadecimal number for transmission in sysex. The note/pitch you select for the starting note number is also the base frequency you will later calibrate your VCOs and VCF to. These are the recommended changes to the CV functions.
  • Page 34 F0 00 20 7A 01 01 02 44 18 F7 (CV1, V/Oct scale tune, MSB = default:68, LSB = changed from default to 24) Changes to the MSB value are probably way out of range, so work with the LSB value. The effect of load on the output will in most cases mean you will be adjusting this value upward.

  • Page 35: Putting It All Together

    6. Set VCO Coarse Frequency slider to minimum / left and Fine Frequency slider as closely as possible to its mid-point, and VCO mode to audio. 7. Connect VCO output to frequency counter. 8. Ensure pitch bend and modulation wheel are centered/zeroed 9.
  • Page 36 1. Make sure all the sub boards have their retaining screws installed. For the 4027-1 cores, use small nylon cable ties to secure them (not included in kit or BOM). Make sure the ratchets are on the back, not the front of the board (as shown). Later, you can remove these, but you cannot replace them without separating the panel from the main board.

  • Page 37: Modification: Add Power Taps For Future Mods

    Parts to perform this change are included in the Synthcube kit and BOM; 4x 1uf film capacitors. The locations for these are marked in silkscreening on the board, and traces must be cut underneath the capacitors footprints before the capacitors are installed.
  • Page 38 The 2600/TTSH EG’s gate inputs are not gate detectors, they are gain stages. If you don’t drive them with a full +10V gate signal, the EGs will never rise to a full +10V on their outputs, leading to reduced signal gain from the VCA outward.

  • Page 39: Modification: External Control - Electronic Switch

    Figure 10 - Standard Gate Booster Installation. On the power jumper here, red=V+ and black = V- Signal Connections: • Gate In > Gate Jack (tip) • Gate Out > Gate Switch (Pin 1) • Trigger Out > Trigger Jack (tip) MODIFICATION: EXTERNAL CONTROL –...

  • Page 40: Modification: Adding A Midimplant

    In jack, the Electronic Switch will be controlled by it. To do this, find the two resistors, de-solder and lift the lower ends of each, and tie these in common to the tip of the External Clock In jack. Figure 11 - Electronic Switch Mod If you then patch up the Electronic Switch thus: •...
  • Page 41 A new version of the MIDImplant was produced for Synthcube that has gate amplitude fixed at +5V. You can identify these by the Synthcube name on the back of the PCB. These newer units require the inclusion of the Gate Booster.
  • Page 42 The internal CV source is the default source, and may be defeated by introduction of an alternative CV to the KBD CV Output panel jack. In this configuration, the CV header on the PCB is bypassed and is moot, but can be used as a test point for measuring the CV. The internal pitch CV source should always be present, to prevent the bus from floating and the VCOs motorboating.
  • Page 43 Figure 13 - Corrected CV Input Logic, Preferred Method, Front Side of Main Board Behavior An internal pitch CV source (MIDImplant CV 1 out) is connected to the CV header. The internal CV source is the default source, and may be defeated by introduction of an alternative CV to the KBD CV Output panel jack.
  • Page 44 Note: protoboards have exposed copper traces. Over years, these will oxidize and eventually fail. If you want this little construction to last longer, apply a sealant, such as Everbrite, or liquid solder mask, to the exposed copper. Figure 14 - Improvised Receiver Board for MIDImplant Integrating the MIDImplant A suggested arrangement is to make MIDI CVs and gate, trigger signals available on the front panel via the re-purposed multiples jacks.
  • Page 45 To implement the panel CV outputs, cut the traces between the Tip pins of the four mult jacks and repurpose them as outputs, thus: 1. MIDImplant CV1 out extended by wire jumper from EXT CV header to tip pin of 1 mult jack 2.

  • Page 46: Modification: Improving Calibration Accuracy

    Bourns makes four-turn trimmers that fit the existing trimmer footprints. They are costly, about $6US at the time of this writing. These are not included in the Synthcube kit or BOM. You may install these in the VCO trimmer locations for Frequency and 1V/Octave calibration, to improve precision. Keep in mind that these merely introduce a gear between the adjustment screw and the resistive element.
  • Page 47 The TTSH reverb driver and return amplifier are compatible with any Accutronics (or clone) model whose second and third digit in the model number are “AB”. The Synthcube kit and BOM specify a 1AB2A1B. This is a two spring, medium decay unit in a short pan. The fifth digit “A” specifies a grounding configuration where both input and output have a common ground with the pan.
  • Page 48 When routing the reverb cable inside the case, keep in mind the biggest sources of induced noise inside the case, and try to dress the cable away from them. In order of noisiness: DC-DC converters, Noise Generator, Internal Clock, Ring Modulator, VCO Sync cables, if installed. The Sythcube kit includes a standard duplex audio cable assembly (a tape deck cable, in fact) for connecting the reverb.
  • Page 49 Figure 17 – Preparing the cable. 5. Insert the copper conductor and its insulated portion into the plug, such that the flared out shield meets the outer part of the plug, and the copper conductor comes out the hole in the tip of the plug.
  • Page 50 Figure 19 - Soldering the Signal Wire 7. Snip off the signal wire protruding from the tip of the plug. 8. Push down the shield wire onto the outer part of the plug, clamp the work and solder the shield to the outer plug.
  • Page 51 Figure 21 - A Finished Plug 9. Repeat three more times. Then, test the cable assemblies for shorts and continuity. 10. If there is excessive solder on the exterior of the tip, clamp the plug and scrape it off with a knife. Don’t heat the work again! 11.
  • Page 52 Figure 22 - Mark to ID the Short Return Cable...

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