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EQ or Bass, Treble, Volume and Balance for audio

KennyMillar

A design I completed a while back is a 4 x 4 audio switch. (ie Basically, any of 4x stereo inputs can be switched to any/all of 4x stereo outputs all at line-level)

The whole thing is controlled from remote touch screens (in in each of the 4 output zones), or via it's built in web interface. There are no user-controls on the main unit.

 

The client wants me to add 'EQ' to each stereo output zone for the next update.

 

Having done a bit of googling about, it seems that almost all audio processing these days is done with DSPs.

Needless to say, this will add a huge amount of complexity to the design - it's all just analogue routing at the moment, no ADCs or DACs in sight.

The main controller board does have a processor on board which isn't doing much except handling the communications with the remote touch screens and the switching logic.

 

So what are the options for adding EQ to the four stereo outputs - It has to be controlled by the exiting processor, again no physical user controls.

Do I need to go down the DSP route, are there any digitally controller analog solutions?

 

The customer might settle for Bass, treble, Volume and Balance as an intermediate release.

 

-Kenny

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  • Hi Kenny,

     

    I'm no expert in this field but I don't think your obligated to go the DSP route. You could set up an analog filter bank (High (Treble), Mid, Low(Bass)) using op amps and the like and then control the gain of EACH of the filters using digital potentiometers which would be hooked up to your uC.

     

    You would route the output of your 4x4 audio switch through the filter bank whose gain would be controlled by the MCU. It's a solution mixing both Analog and Digital worlds. If your more familiar with analog filter design I think this solution is reasonable.

     

    Let me know what you think.

     

    Jorge Garcia

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  • Hi Kenny,

     

    I'm no expert in this field but I don't think your obligated to go the DSP route. You could set up an analog filter bank (High (Treble), Mid, Low(Bass)) using op amps and the like and then control the gain of EACH of the filters using digital potentiometers which would be hooked up to your uC.

     

    You would route the output of your 4x4 audio switch through the filter bank whose gain would be controlled by the MCU. It's a solution mixing both Analog and Digital worlds. If your more familiar with analog filter design I think this solution is reasonable.

     

    Let me know what you think.

     

    Jorge Garcia

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  • in reply to Jorge_Garcia

    Jorge,

     

    Thanks for the response.

    The analog route is interesting but adds a lot of components to the count.

     

    I found this chip TAS3204 from TI which is a s-o-c but it's a bit over kill, as all I'd use are the analog inputs and outputs, and in addittion, it requires a load of DSP programming.

    I'd have thought there would be a plethora of audio processing chips to choose from. Analog in, Analog out with SPI or I2C for control would be my ideal solution. Maybe it's just wishful thinking!

     

    Thanks again :-)