Clean Release Notes: Rev 3 PCB

The PCB and Panel have no known errors. The Rev 3 PCB is blue.

Label Clarifications

R27. This is at about 9 o’clock on the board. The label is partly obscured by misplaced “LED”
D3. This is at 6 o’clock on the board. The label is AWOL: it just has the K.
For the shrouded power header, make sure the slot in the shroud (box) is on the inside of the board, not facing out.

Component Selection

Diode D5 is shown as 1N4148, however it can be a BAT43 like the other diodes.
The bus Gate and the +5V line on the power cable are used by this module, so you cannot install a 10-pin power socket instead of the shown 16-pin socket.
The 4HP module is tightly packed. There are small “micro knob” for the T18 shafts that work better than, say, Davies style knobs, carried by Thonk in 2019. (However, you may also consider locating the module so that its neighbour provide some clear space, especially if you have generous sized fingers.)

Test Points:

TP1: Gated Velocity CV = Gate limited by Velocity.
TP2: Output of first lag generator for “Phrase AR”; same signal as drives LED
TP3: Envelope CV before final amplification/rectification
TP4: Envelope output CV
TP5: GND

Customizing: Pimp my Clean

Clean will act as an gate detector on analog signals. Diode D5 will prevent spurious triggering on low-level noise, however if you want greater sensistivity, then short out D5.
For sharper attacks, reduce R4 to a few ohm.
For longer fade-ins (and phrases) increase the value of C3. Note that there may be some delay effect as well as the fade in.
To remove the initial low-level CV, remove R35 and R21. Note that the position of the accent knob will usually have an effect here as well.
In theory, reducing capacitor C3 (e.g. to 10 to 100 nF?) will allow the same circuit to function as a kind of envelope follower that discriminates against small bursts of spurious signal. This has not been tested.
In theory, reducing both C3 and C4 to operate at audio rates will convert the unit into a kind of squaring waveshaper with angled peaks; for this use a 1uF bipolar DC blocking capacitor instead of D3 would be appropriate. This has not been tested.

Knob Oddness: Accent

The Accent knob needs to be explained. If no signal is connected to the Velocity input socket, then the knob controls a fake velocity signal: 0% will be 0 velocity and no note will sound, 100% will be equivalent to loud velocity: so probably 80% to 100% is a good setting. If there is a velocity signal attached, then 0% will be that velocity sign and 100% is equivalent to a full velocity: this may be backwards to what is expected as the accent signal sets how soft a low velocity signal is, more than how loud a high velocity signal is.

LED

The LED follows the phrase envelope: if it is on, then a fast next note will use the attack of the “Note AR” (i.e. portato). You know the portato effect in available when the LED is on; when it is off, your attack will be determined by the phrase AR knob.

Gate

If nothing is connected to the Gate In input socket, it will switch to use the Gate signal provided by the Eurorack bus, if any.

Signal Levels and Use as a Slew Rate Limiter/Lag Generator

The module is designed for typical Eurorack signal levels. However, it does not treat the Gate In as a gate signal but have different envelope responses to different levels. So Clean can be used as a dual slew limiters or lag generators, with eccentric linearity and a kind of VC control from the Velocity input.