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ModSlewer CV Slewrate Shaper

CV Slewrate Shaper


  • • CV Slewrate Shaper
  • • RIP Håkan Müller

Video clips

Håkan Müller, creator of the Hamu devices passed away in May 2018. He suffered from ALS for 3 years and finally decided to leave. To honor Håkan, you can use his Rack Extensions for free from now on. Please remember Håkan when you are inking your rack purple.

One more CV tool for your collection.

This time it's a 12 'channel' slew device.

  • Smooth out transients on any CV signal
  • Slow and soft transitions between CV levels
  • Slide between ModPanel patch output levels
  • Transition times from 0 ms to 30 seconds
  • Separate rates for rising and declining level
  • Individual modulation inputs for up and down rates
  • Global modulation for up and down, adds to individual
  • Switch between constant time-per-volt or constant time-to-target

Product details


Simply put, the ModSlewer is a kind of low pass filter with separate rate settings for the level rising or declining.

The ranges for the slew rates go from 0 ms to ~30 s per Volt on a continuous logaritmic scale, with separate knobs for up and down rates.

You can switch to align times to target level, i.e. the transition time for any input change will always equal the set time independent on the change size. More like attack and release really.


Individual modulation inputs for each slew rate is included, so you can play around with intriguing CV interdependencies.

There are also global modulation inputs for up and down rates, affecting all 12 slewers. If the global up is connected, and not the global down, the global up modulation level will be applied to both up and down slew rates alike.

The setting of each slew rate is the sum of knob + individual mod + global mod. The resulting slope is roughly indicated by the 'semaphore' LED meters.


In addition to the main CV signal input and output of each slewer, and the modulation inputs dicussed above, there are also outputs from the slew logic. There's an 'up gate' which goes high when the output is rising due to higher input, and a 'down gate' going high when the output is declining to a lower input level. When input and output levels are eaqual,both gates are low, at 0.0V.


Notice that the relation between input and output of each ModSlewer is actually very simple. In rate mode, slow changes on the inputs will pass through unaffected to the outputs, while aligned time mode will act more like a delay. For visibility, there are vertical LED bars indicating the current level on the input and oputput sockets.

Short rates - a few milliseconds - can be used to remove CV edginess and avoid clicks, giving softer transfers at sharp CV level changes like 'curve' outputs from a Matrix.

Longer rates are very handy for setting transition times for ModPanel outputs and similar signals, e.g. when changing patch, or any situation where there is a need or wish to really slow down CV level changes. In these situations you may prefer to have the Align Time option active, making outputs reach the target (=input) level at the same time.

Thanks to the modulation inputs the usefulness will increase to handle more advanced tricks. For instance a very long slew rate will almost act like a sample and hold, which can be activated - and released - by using the mod input sockets.


  • 1.0.2 First release 2014-09-25
  • discontinued



Released: 2014-09-26
Version: 1.0.2