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Multiple TAS5746M processors running different Hybridflows

Other Parts Discussed in Thread: TAS5756M

I am curious about section 9.2.3.2 of the TAS5756M datasheet.  Here is a quote:

9.2.3.2 Advanced 2.1 System (Two TAS5756M devices) In higher performance systems, the subwoofer output can be enhanced using digital audio processing as was done in the high-frequency channels. To accomplish this, two TAS5756M devices are used- one for the high frequency left and right speakers and one for the mono subwoofer speaker. In this system, the audio signal can be sent from the TAS5756M device through the SDOUT pin. Alternatively, the subwoofer amplifier can accept the same digital input as the stereo, which might come from a central systems processor. In advanced 2.1 systems, any HybridFlow can be used for the subwoofer, provided the sample rates for the two are the same. While any of the HybridFlows can be used, it is highly recommended that only mono HybridFlows are used for the subwoofer. Doing so streamlines development time and effort by minimizing confusion and complexity.

Does this imply that I may run different Hybridflows on different TAS5756M processors and not have to worry about synchronizing the output?  I would like to run HF3 on one TAS5756M to create tweeter and mid-range signals.  I would also like to feed the same signal into a second TAS5756M running HF4 to create a woofer signal.  I would be feeding each TAS5756M processor the exact same I2S signal.  Will the outputs from both TAS5756M processors be synchronized?  In other words, is the processing delay associated with the processing of HF3 the same as the processing delay associated with HF4?  

  • Hi Tyler,

    Under the conditions of your setting, There will be a delay due the different Hybrid Flows used on both devices, I measured in the EVM around 300µs difference between the amplifiers when using HF3 for Stereo device and HF4 on Mono device. 

    Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • Thank you Diego.
    A difference of 300us is about 4 inches at the common speed of sound (~340m/s). Meaning, a speaker cabinet designed with an HF3 driven high/mid range and a HF4 driven low range would need the high/mid range speakers mounted four inches behind the low range speaker to keep the sound wavefront in sync.

    Do you think the difference between HF3 and HF4 is worst case? The processing pipelines of HF1 and HF4 seem to be quite similar. We suspect that they are much closer to sync. If you still have your experimental setup, could measure that combination as well?

    By the way... could you please put in a request for a mixer to be added to HF7. If we could do tweeter, mid and woofer processing all in HF7 then that would be best for our application. The only thing missing from HF7 is an input mixer. If we had something that evenly mixed both left and right channels for mono (woofer), then we would be all set. In addition, we would pick up 96Khz support.

    Thanx
    Tyler.
  • I'll second the request for adding an input mixer on HF7.