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Model 509 Rotating Limiter Modules

Rotating Limiter

The Back Story

For many years, we made the Model 508 Phase Rotator. This device didn't make anything any louder, but it made a limiter more effective by making waveforms more symmetric and easier to limit. It was a great tool for asymmetric signal sources like vocals, horns, or close-miked strings.

People liked it but found it cumbersome to use, so we integrated a very fast broadcast-style limiter into the same module along with a phase rotator for complete processing in a single space. This is the new Kludge Audio 509 Rotating Limiter.

This is the new Kludge Audio 509 Rotating Limiter

The rotator is an all-pass filter that alters the phase of each component the signal differently depending on its frequency. If a 50 Hz signal is passed through, it will come out with identical polarity on the output. But, if an 800 Hz signal is passed through it will come out with the polarity completely reversed. A side effect of this adjustment is to make the waveform more symmetric.


This is what it does. The top waveform is a typical female vocal recorded with Neumann U87. It's asymmetric, with peaks in one direction greater than in the other, because the human vocal cavity is just that way.

The bottom waveform has been processed by the phase rotator. It's more symmetric, with peaks more evenly distributed between the top and bottom of the waveform. This means when you limit it, the limiting will be more even between the top and bottom, and you can limit it more aggressively without distorting it. It is especially useful on severely asymmetric waveforms like brass instruments and vocals.

After the phase rotator we have included a high speed opto limiter with a simple threshold control, incredibly fast attack, and controlled decay that depends on how hard it limiting. This is not your like an old 1176, it lets you limit harder than that! It uses a modern opto element with a very sharp knee and very fast operation.

Going Forward

You can use the limiter alone without the rotation, you can use the phase rotator alone with an external compressor or limiter, but you'll find you like using them together because they work as a team.

There's no magic to it, but in the modern day when everyone is trying to eke out every little bit of loudness in their tracks, the phase rotator can help you bring vocal levels up a tiny bit and keep vocals front and center in your mix. It's a great help in getting the radio-ready sound. And it is available right now at your dealer for $529.

For this or any other Kludge Audio products, please contact your local professional recording products dealer, purchase off our page, or contact us directly.
Last updated 10 Mar. 2023
Scott Dorsey (kludge @