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TAS5756M's Harmonic is too large

Other Parts Discussed in Thread: TAS5756M

Hi all,

      Our TAS5756M card play 16bit, 44.1K,1KHz sine wave. We are using 2 TAS5756M to operate in

Double PBTL mode.But the TAS5756M's Harmonic is too large,maps are as follows:

 

How do we improve it?

Thanks.

  • Hello,

    Sorry for the delay response. Did you get this resolved? Are you using our EVM and GUI? What PVDD, load and power level are you using to measure THD+N?

  • Hello,

    See figure 52 in d/s below. The plot seems to be inline with TAS5756M typical THD+N performance in PBTL using 24V and 4-ohms load.

  •  HI,

    Damian Lewis, thank you for your reply.
     

    We haven't tested your EVM, EVM to you, we are still pending.  Our PVDD is 24V, and 4-ohms load.

    The following pictures is our board in 72W . We can see the THD+N is 5.5%,but See figure 52 in d/s below. The plot seems to be inline with TAS5756M typical THD+N is less than 1%.

     

    More important is, in 2K, 3K,5K,7K... have harmonic.

    Thanks.

    Xu

  • Xu - here are a couple of observations:

    Firstly when measuring THD you must not use the A weighting filter in the AP's distortion analyser.

    Secondly you are, in my opinion, clearly clipping the amplifier in your last post. This is shown by the high THD level of 5.5 % and the high levels of odd order harmonics in the FFT analysis. I have always found it is very useful to attach an oscilloscope  to the AP's analyser output so you can see the actual waveform at the speakers.

    Hope this helps!

    John Dawson