TAS2780EVM: How to configure for max power and max volume

Hi Kessler, 

Can you please share the ppc3 file you are using and I will check it on my side?

Are you using the EVM with USB for the audio input? if you are using a sperate TDM source it could perhaps be a bit shift issue

can you please check section 4.2 in the EVM users guide and confirm the default jumper settings are correct  https://www.ti.com/lit/ug/slou551a/slou551a.pdf? 

Also, please double check the audio settings on your PC. 

Regards,
Arthur

Hi Arthur,

Yes I can. Here is a link to test1.ppc3 : https://dimontegroup-my.sharepoint.com/:u:/p/kkerr/EWN97jV7fhxJiGIspbfStKABbxx9RuPkiJIg3bpUAkqaGw?e=IkERJV (I had trouble adding the file using the upload feature / dragging and dropping).

I am using USB for the audio input and confirmed that the PC audio settings are set per section 4.3 of the user guide. In addition my jumpers are set per 4.2 of the user guide other than J30-J33 which are disconnected. 

Thank you,

Kessler 

Hi Kessler, 

I checked with your "test.ppc3" file and didnt find any issue. I am able to pull about 1.5A from my 20V supply. - same jumper settings as you.

can you please triple check the windows playback volume? - i know i sound like a broken record, but something seems off with the system

Also would  be good to check in the TI audio control panel as well

Regards,
Arthur

Hi Arthur,

Thanks for the reply and support so far. It's good to know that the PPC3 configuration I am using should be working.

I've double checked the settings and they do appear to be set appropriately. I did uncheck the Safe Mode checkbox in the TI audio control panel and redid my testing and now I am getting higher current draw from the power supply 24V 0.42A (~10W) but still isn't close to the expected 30W like you were able to do. 

I have an additional audio amplifier board which I plan to test Monday to see if this is a board problem. I'll let you know what I find. Please let me know if you have any suggestions as well?

Thanks,

Kessler 

Hi Arthur,

I've unboxed our other TAS2780EVM today and confirmed jumper settings and Windows Sound settings. Using the Test1.PPC3 file I see about 310mA being drawn (with my PSU set to 24V this is about 7.5W). I've been using this youtube as the audio input for the TAS2780: https://www.youtube.com/watch?v=hIDAbW-JbC0. 

Would you be able to share the ppc3 file you are using on your end and the audio file / source? I would like to see if it is either my ppc3 file or audio source that are the cause for the difference between your set up and mine.

Thanks,

Kessler  

Hi Kessler,

I have been using audacity. which we where using in the other thread to check the IV-sense. in audacity you can select Generate->Tone and set the amplitude to "1" to get a 0dBFS input to the EVM. which should be about 30W output

Regards,
Arthur

Hi Arthur,

Thanks for the advice on Audacity. I was able to verify that the TAS2780 draws momentarily above 20W on the 4 Ohm 45W speaker I have. The PSU and current probe should that I have an 1.12A current draw but it quickly decreases and stabelizes to around 260mA. Do you know if this is expected from the TAS2780? 

On another note I also began looking at the output signals on an oscilloscope and see quite a bit of noise on the output of the TAS2780 and wonder if this is relared and would like to get it cleaned up if possible. Reviewing the schematic and datasheet the TAS2780 claims it does not need filtering on the output but was curious if based on the waveform below would you recommend it? I am playing a 523Hz tone using Audacity and can see a sine wave of the frequency but also many square waves which I assume is the PWM freq of the H bridge. 

Thanks,

Kessler 

Hi Kessler,

When I tested with your ppc3 file i did not see the same behavior where the current will quickly decrease, in this case it could be one of the limiters. is everything disabled? could you also check by recording the V-sense when the current drops from 1.12 - 260mA? we can see if the amp is attenuating or if some other phenomenon is happening. such as the speakers R increasing as it heats, but for a copper voice coil the R increasing 4x is not really expected. 

this is the PWM of the class D. 

a filter on the output is not needed to get the full audio performance. - really the speaker is acting as the filter

the class-D is switching at 768kHz far out of the audio band, and due to the inductance of the speaker this content will not contribute.to power consumption or heating of the speaker. and ofcourse not be audible. 

If you want to check the output waveform there are two options

1) create a simple LC  or RC LPF ~40kHz and you can check it on the scope.

2) use the V-sense recording from the device. which is like a LPF+ADC  

Regards,
Arthur

Hi Arthur,

I can confirm that I do not have any limiters on. They are off in PurePathConsole on the TAS2780EVM page. Attached is the recording of Vsense and Isense. The top is Isense. As you can it quickly decreases at start up. The blip where Isense goes to zero is when I disconnected the speaker to confirm which channel was Isense. 

This is with a stock EVM kit without any modifications being made to the output filter. 

Thanks,

Kessler 

Hi Kessler, 

do you by chance have any audio processing affecting your USB output. in windows sounds -> TI USB -> Properties -> Advanced. do you have any checkbox like "enable audio enhancements' or something similar?

Regards,

Arthur