Dynamic Bass Boost Basics

Hallo Everyone

I am quite new to sigma studio. Currently implementing one of my first projects in sigma dsp using ADAU1452. for my application i am using the Dynamic Bass Boost algorithm from the ADI library. I took a look a analog devices wiki but the documentation is not so clear, can some one please explain me the working principle in bit details specially with the parameters Time constant, where we are just inputting one value to determine the attack and the release time and also the compression ratio part. I will be really grateful for help

  • 0
    •  Super User 
    on Dec 25, 2015 9:01 PM

        Hello skhan,

        Yes the documentation could be better.  The wiki does suggest adjusting by ear, but this is a bit daunting with so many parameters involved.  This also makes full documentation rather difficult -- the number of graphs multiplies like those typically found in data sheets, while comprehension suffers.

        I saw that Dave T. in a separate thread promised to consult with the algorithm designers to get some better docs.  In the meantime, we can gain some insight by testing the algorithm.  This can be easier than it appears, because we can have the -1452 test itself with some programming.  Two projects for the -1452MINIZ eval board are attached below -- one for time constant, the other for frequency response.

        Time Constant

        This schematic applies a step-amplitude signal to see how the Dynamic Bass block responds:

    The block's Time Constant appears to refer to the approximate total response time -- for example, I get the response at left when set for 500 mS.  Shorter time constant measurements may be limited by the response time of the Real-Time Display.

              Frequency Response

         This schematic measures the Dynamic Bass block's response to frequency at a given amplitude.  I had done a similar project for the ADAU1701, but this one is much more straightforward thanks to the Base-2 log, and 2^x functions available on the -1452:

         Here's some results I've found with the settings shown:

         With a full 0 dB input, the block does not boost bass at all -- in fact, it cuts bass below the frequency set in the black box under the slider (40 Hz shown).  Thus, set this box to the lowest frequency you wish to reproduce.   Apparently the Dynamic Bass block is designed to protect your speaker from unneeded frequencies below the desired minimum.

         Reduce the input, and we see bass boost.  The amount of boost depends upon the Compression Ratio (lower provides more boost), as well as where your level is between the Upper (no boost) and Lower (max boost) thresholds.  The maximum available boost appears to be:

    Boost = (Upper - Lower)  / Comp Ratio

         By running these projects yourself as well as doing listening tests, hopefully you'll find a good match to your application.

         Best regards,