Applying dynamic EQ filtering based on signal amplitude
Hi!
I'm working on a project with some small size PA speakers that are intended to be used mostly for live speech (e.g. conferences)
I would like to experiment with the idea of applying dynamic filtering or amplitude reduction to the microphone input at certain frequencies, when these frequencies are present above a certain threshold. Much like you can do dynamic EQ's in some mixing consoles and DAW's.
For example, let's say I've determined that a Shure Beta58 needs a ~6 dB cut at 300 hertz, and a XYZ mic need a 9 dB cut at 600 hertz etc, but i don't want these filters to kick in for other microphones.
My own ideas so far, that I haven't had success implementing:
I have tried driving an index-selectable filter with a log I haven't had much luck with this, and I haven't figured out how to do it for filters at different frequencies.
I've also considered using the RTA to Output signal detector, however I can't find a filter block that accepts an incoming amplitude as a trigger for its boost.
I could also use the multiband compressor, however it seems a bit overkill, and the banded approach seems not the perfect tool for the job.
I hope someone has a tip to get me going, or where to read up on how to do this :)
DSP is adau1462.
Audio Signal Processors
dynamics processors
equalization
SigmaDSP Audio Processors
dynamic
microphones
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Hello ARanch.
Try this project.
www.dropbox.com/.../SidechainBandDynEQ.zip
And as for the mic correction you can try to make an impulse response library and feed these data to an FIR filter on the DSP memory via your MCU, or you manually EQ those mics and feed your parameters to a cascade of biquads in the DSP. Whatever fits the bill.
But I might advice against that. Better to have someone here to eq that thing manually (and handle feedbacks).
Hi CopperMaze . I have similar requirement to the original posted question. Would you be able to reshare this project with me? The Dropbox link is no longer valid. Thanks!
Hello,
The multiband compressor is the first thing I thought of, but you already mentioned it as not the best solution for you, but I'm not sure why ?
You want to dynamically adjust the signal level in a certain band of frequencies correct ? You only need a single band ?
Hello ARanch,
One approach might be to use a Holter's EQ. This block has an input for the gain from an external source. I had drawn up an example of using this block a while back. The project I attached is setup to use the two pots on the RevB eval board. The other bands are just using DC cells. So adapting this is a matter of using envelope followers to sense the level and then sending that to a table to produce values that the block expects for the gain.
Dave T
ADAU1452 Five band Graphic using Holters EQ.dspproj
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