The two products use the same PCB and Panel (reversed).
Pads labels the four IO pairs 1,2,3,4; Fix labels the four IO pairs as CV, AT/BC, Vel, Gate which may be useful for some users.
Schematic of one section; this is repeated,
and you choose which components are relevant to you.
This is a preset module. You (the builder) can add or adjust components to get the functionality you require.
- Problem: Your CV or signal is too loud (too high level). This frequently happens when interfacing your module with things designed for non-Eurorack systems that run at a “hotter” level.
- Solution: Install the trimpot to reduce the level of a signal. A 50k single-turn trimpot is usually good here, but 10k to 100k could be used. (If you don’t install the trimpot, you need to put a link in. However, if you do this the input and output act as a passive mult, in which case the usual care about not plugging two outputs together applies.)
- Problem: Your CV signal goes negative, which is not expected by the next module.
- Solution. Install the diode to ground and the current-limiting resistor. This will cause signals greater than the “diode drop” to be diverted to ground. A diode like the 1N4148 can be used with a resistor <4.7k; but a Shottky such as BAT85/BAT43 or Germanium diode with a resistor of a few hundred ohms might be better if you need a sharp cutoff. (If you don’t need this, do nothing.)
- The diodes are D2, D4, D6 and D14. Their current-limiting resistors are R2, R4, R6, and R8.
- Solution. Install the diode to ground and the current-limiting resistor. This will cause signals greater than the “diode drop” to be diverted to ground. A diode like the 1N4148 can be used with a resistor <4.7k; but a Shottky such as BAT85/BAT43 or Germanium diode with a resistor of a few hundred ohms might be better if you need a sharp cutoff. (If you don’t need this, do nothing.)
- Problem: Your CV or signal is jumpy or noisy or has a high oscillation or ring.
- Solution: Install the capacitor to ground. This will cause higher-frequency signals to get diverted away from the signal path. The exact frequency will vary with the trimpot, but you can expect it to be between 1nF for supersonic sounds and 100nF for audible sounds. (If you don’t need this, do nothing.)
- Problem: Your CV or signal may have bursts that are crazy loud (such as self-oscillations), or you have to connect to a module with strict input restrictions (such as some micro-controller-based modules) and want to make sure you have safe levels.
- Solution: Install a Zener Diode with the appropriate value. Install the current-limiting resistor of a few hundred ohms also if you like: otherwise install a link instead of the resistor. The resistor may also change the threshold levels of the diode. Note that the Zener Diode comes after the trimpot in the circuit.
- The Zener diodes are D1, D3, D5, and D7. Their current-limiting resistors are R1, R3, R5, and R7.
- Solution: Install a Zener Diode with the appropriate value. Install the current-limiting resistor of a few hundred ohms also if you like: otherwise install a link instead of the resistor. The resistor may also change the threshold levels of the diode. Note that the Zener Diode comes after the trimpot in the circuit.
Each of the four sections is electrically isolated: they do not share a power supply (of course, there is none) and they do not share a common ground.
An example of a Fix/Pads module.
This one has had sections installed for Gate, Vel and AT/BC
(each with a trimpot and diode)
but not yet the CV section.
Freak Out! 