audio processing

[mister_e]

http://focus.ti.com/paramsearch/docs...s&familyId=378
look for TAS3002 and TAS3004. Yup not as easy as ABC but i already used them and they gives decent results. TAS3002 will probably be the smartest choice. Of course you can find many other from aother company... google search dude

For the limiter, you're right. You read the signal in parrallel with the Audio Processor then you play with the volume VIA I2C bus. TAS3002 include a compression/expansion module but i can't comment on that section as i didn't used it.

Depending your skills, it willn't be easy to do, but really interesting project you have on hand now. Good luck!

[Sebastian]

Hi,

I just found your thread while searching for information on a TAS3002. I've some experience with microcontrollers (80C552, PIC) and know how to use an I2C bus.
My next project will be a midi controlled distortion unit (for guitar) and I'd like to use the TAS3002 for that.
However, I've got no idea of these "strange" filter coefficients that I need for the biquad filters (I need a 4 or 5 band parametric eq). Can you help me with some formulas or other calculation tools?

Thank you
Sebastian

Sorry for my English, I'm German.

[mister_e]

Yeah Biquads are a bit hard to figure out. TI have a software called ALE (Automatic Loudspeaker Equalisation) you sould aksed them and play a little bit with. It should be enough to give you some hints.

Now, do you really need all feature of the TAS3002? DRC, Mixer, Bass, Treble, Biquads and such?

If you just need a simple equaliser you should jump to the TDA7416.

But TAS3002 is a reaaaaallly cheap'n great Audio DSP

[Sebastian]

Hi,
Thanks for your fast answer. The TDA7416 really seems to be an alternative, at least it might be much easier to set up the equalizer. I don't need all the features of the TAS3002, but I couldn't find a distributor for the TDA, yet.

All in all the TDA should be the better choice, as the controller doesn't have to calculate these filtercoefficients... and that is the main problem.

Thanks for helping me

Sebastian

[Sebastian]

I've just asked TI for the ALE software.. let's see if they gonna send it to me....

The TDA is quite good but I cannot realize a full parametric eq with it..

Sebastian

[mister_e]

i agree, but doing all the biquads maths within the PIC

Maybe there's some alternative. I didn't spent too much time with the TDA7416 as now, neither the datasheet. It fitted perfectly for a previous customer request so i used the minimum... Eq and Spectrum.. not much.

I'm pretty sure they're something else 'round before playing with DSPics. For a single ended project i guess you don't want to waste too much of your time on it

[Sebastian]

Yes, that's another main problem.. the maths. I hope to get the ALE software to see if it is possible just to store some coefficients and not calculate them within the pic. However (I think), all parameters change (all 5) just by changing one value (for example the gain) of a filter.. so every coefficient has to calculated, not only one.

Hm... I don't mind to spend some time working with the TAS3002 as it seams to be a very interesting IC and still easier than a "real" DSP, but first I should know how difficult it is and whether it is possible with a pic at all... I have a free C-compiler, but it can only manage 16 bit variables.. so thats the first border.. difficult as a 4.20 data format is needed.


Sebastian