Papareil Labs
Quantix-8

I don't own a Papareil Synth Labs Quantix-8 CV quantizer / wavetable oscillator module but have repaired them.  There is some discussion of the Quantix-8 on the Electro-Music and Muff's Modules forums.  This is a very interesting module with multiple modes of operation.  The inclusion of PC software for editing and creating the waveforms makes this a very useful module.

 

Quantix-8

This particular module had garbled output which I traced to erratic operation of the LTC1099 ADC.  This ADC generates the lower 8 address bits for the waveform memory from the input ramp waveform.  In this image you can see the ramp input waveform (magenta) and the processed ramp input to the ADC (yellow).  The bias control is adjusted correctly to produce a zero output at the beginning of the ramp waveform.  The DB0 output (green) should toggle uniformly throughout the entire waveform to correctly address the LSB of the sample memory.  The other seven output showed similar erratic behavior.

 

I traced the output problem to the clock frequency which was up over 600 KHz .  The conversion time of the LTC1099 ADC is specified at 2.5 ÁS and lowering the clock frequency to 400 KHz established reliable operation.  Proper adjustment of the input attenuation and bias controls are necessary to produce a uniformly continuous waveform as can be seen in this image of a sine wave output.

 

 

Quantix-8 Tips & Modifications

  1. The LTC1099 ADC has a specified conversion time of 2.5 ÁS which is 400 KHz.  I replaced C6 with a 4n7 capacitor and adjusted the 4093 oscillator frequency to 400 KHz to for proper operation of the input ramp ADC.

  2. The Gate I/O jack should be wired to J4 which connects to pin 24 of U15 (this is in error in V1.1A documentation but correct in V1.1B documentation).  I added over/under voltage protection for the PIC with a 1K resistor in series to the jack and a diode to ground and a diode to +5 volts on pin 4 of U15.  The PIC spec is +/- 0.3 volts so you might want to use schottky diodes for a low voltage drop.

  3. The Zero Out jack should be wired to J3 which connects to pin 4 of U15 (this is in error in V1.1A documentation but correct in V1.1B documentation).  Although this is an output, I also added the same over/under voltage protection for the PIC with a 1K resistor in series to the jack and a diode to ground and diode to +5 volts on pin 24 of U15.  Again, you might want to use schottky diodes for a low voltage drop.

  4. The Zero Detect LED is wired with the anode connected to +5 volts and the cathode connected to J11 pin 16 (this is in error in V1.1A documentation but correct in V1.1B documentation).  You adjust the +/-5 volt ramp input level and bias until both the Zero Detect and Overload LEDs just begin to flicker.

  5. The values for R58 and R36 are shown incorrectly on the V1.1A and V1.1B implantation schematic (e.g. component values).  R36 is 5K (is shown as 10K) and R58 is 10K (is shown as 100K).

  6. I could not reliably transmit to the Quantix-8 on my Windows XP computer and received the error message: The port is transmitting data to the device.  Wait until the data has been transmitted, and then try again. Increasing the Sysex Send Delay to 30 resulted in reliable communications for my computer.

 

 

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