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Original question:

TLV320AIC3120EVM-U: Audio Distortion

TLV320AIC3120EVM-U: Audio Distortion

Scott Gaetjens
Intellectual 270 points
Part Number: TLV320AIC3120EVM-U

Hi,

I'm back on this project.  I put a sine wave through my EVM and measured the BTL on both sides of the speaker through a low pass filter.  I am playing the tone through this 4 ohm speaker: https://products.owolff.com/acoustics/speakers/OWS-4065T-4C

I'm providing 5.5V for SPKVDD from an external power supply.

Here is a screenshot I took of my oscilloscope:

The sine wave is ~4.8Vpp and is beginning to clip.  I can hear some distortion in the speaker.  4.8Vpp = 1.7Vrms, so the average power delivery into the 4 ohm speaker is 1.7Vrms^2/4 = 722.5mW.  That's nowhere close to what the part claims it can do - 2.5W into 4 ohms.  Do I have something wrong in my configuration?  All I did was allow the default init script to run, then I changed the analog attenuation to 0.

I'm using the signal generator that is part of Soundcard Oscilloscope to generate a sine wave at 500Hz.

I turned the input signal up so the clipping is easier to see.

My ΔY is 5V.  Shouldn't I be able to get a lot more out of this thing before clipping starts?

I experimented with the DRC but wasn't able to find a happy setting.  The only way I can eliminate the clipping is to turn my Windows volume down, but then the audio level is too low for our application.

  • 0
    TI__Mastermind 29745 points

    Hi,

    If you look at the datasheet class-D speaker performance on page 17, you can see the THDN is not greater than 60dB with 24dB gain (the setting in the GUI script) and with 4 Ohm load. The 8 Ohm load is a little better, but still it's between 60dB - 70dB. You can measure the THDN with an audio instrument with your test condition.

    Regards.