Ladder Multimode Filter

Primal Audio I/S

Analogue Filter
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Ladder Multimode Filter

  • • Industrial circuit simulated ladder filter


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LADDER is an analogue modelled multimode filter. Based on the characteristic ladder filter design used in the iconic Minimoog synthesizer, LADDER brings the smooth, organic sound of the original unit to the Reason Rack. LADDER is build on cutting-edge DSP rooted in techniques used in industrial circuit simulators in order to accurately model its analogue components. Furthermore it extends the original filter with a mixer with simultaneous low-pass, band-pass, and high-pass sources and a stereo-spacing effect, resulting in an extremely versatile unit capable of all kinds of effects from gentle distortion to complete analogue mayhem.

LADDER is included in our FILTER CLASSICS bundle.

Product details

In order to faithfully capture the character and response of the analogue filter we have modelled the exact behaviour of the electric components by bringing techniques from industrial circuit simulators (e.g. SPICE) into the domain of real-time audio processing. A topology-preserving, zero-delay feedback loop resolved by a heavily optimised differential solver ensures that the sheer authenticity of the analogue sound is preserved and raises the bar for sonic realism to a level unseen in the Propellerhead Shop.

Warning: We’ve used every possible trick to reduce the CPU usage, but, stellar sound comes at a price. However, we truly believe that the quality justifies every used CPU-cycle!

Introduced in 1970 the Minimoog was the first mainstream portable synthesizer for musicians. Still today it is one of the most popular and sought after synths and is famous for its excellent and by many considered the ultimate analogue filter in a portable synth.


  • MULTIMODE MIXER: Mix between simultaneous low-pass, band-pass, and high-pass sources
  • AUDIO FM: Use audio signals to modulate the filter
  • SPACING: Spacing-control for stereo or phaser-like effects
  • INDUSTRIAL CIRCUIT SIMULATION: We use techniques from industrial circuit simulators to accurately model electric components
  • SELF-RESONATING: Even when aggressively overdriven
  • CPU-EATER: We know it, she’s hungry, but stellar sound comes at a price!

All product names used are trademarks of their respective owners, and reference to these here in no way constitutes an association or affiliation with Primal Audio. All trademarks are solely used to identify the products whose sound was studied during the development of LADDER.