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Limiter working below -24dB

SigmaDSP & SigmaStudio matias_black Aug 29, 2018 00:00 2 replies Original on forum ↗
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matias_black Question
Aug 29, 2018 00:00

Hi, my name is André. I have a problem working with Limiter. I need to configure the threshold of limiter up to -36dB. But, when i change in MCU the threshold below -24dB (by example -24.5dB), the indicator led turn on and i dont have signal in my circuit.

Thanks for the help.

KJBob Reply
Aug 30, 2018 00:00

Hello,

The Limiter block allows only a threshold range from -24 to +24 dB, so if your MCU attempts to load its threshold parameter outside this range you'll find unspecified results. However you can work around this by adding pre and post gains, as shown below:

When your desired threshold is within range, set both gains to unity and adjust the limiter as usual. To achieve a threshold below -24 dB, set the limiter for -24 and adjust the gains to make up the difference. For example, to get -30 dB -- make the pre-gain 2.0 and the post-gain 0.5. The limiter sees a signal 6 dB higher than it would otherwise, so it acts as if its threshold is -(24+6) = -30 dB. The post-gain is always the reciprocal of the pre-gain.

Best regards,

Bob

Limiter-range_sch.png
Limiter-range_sch.png
matias_black Reply
Aug 31, 2018 00:00

Hi KJBob, thanks for the help. Problem solved.