TAS2781: TAS2781 and TAS5825M Smart Features

Hi Severin,

The TAS2781 uses IV-sense, (speaker current and speaker voltage sense) as feedback for the speaker protection. this means that as the speaker heats up and ages, the TAS2781 can detect changes in the speaker parameters and account for them. this will increase the life span of the speaker. this IV-sense feedback is needed in TAS2781 because of the target market. TAS2781 is intended to be used in portable electronic devices that may have small speakers, (Laptop, Tablets, Smart Home devices) these devices may have speakers rated at 2W and the IV-sense allows us to drive them as close to that limit  as possible to maximize the loudness and low frequency performance. Since we drive the speaker as hard as we can if the speaker parameters change with age this could result in damage to the speaker overtime if IV-sense is not used. 

TAS5825M does not have this IV-sense feedback, but rather it uses the initial speaker parameters for the lifetime of the speaker. This is OK for TAS5825M because of its target market. TAS5825M is popular in TVs, Soundbars, and large portable speakers. In these systems the speakers are typically rated at larger power and are not often being driven to 100% of their rated power, and therefore small changes in the speakers parameters don't risk damage. In this case IV-sense was not included to decrease device cost and package size.

Regarding EMI Performance. The recommended schematic for TAS5825M includes a reconstruction LC filter at the output. This filter will effectively remove all Class-D switching from the amplifier output. While TAS2781 Does not require this filter. Sometimes we will include a 300Ohm FB and 1nF cap filter if the EMI performance is not meeting the requirement. (either CISPR32 or customer specific requirement)

Since the TAS5825 Filter is a much lower cutoff compared to TAS2781 the EMI performance will likely be better on TAS5825M, unless the same LC filter is populated on TAS2781.

No, We do not have a plan for a stereo TAS2781.

Regards,
Arthur

Hi Severin,

no, these features on not the same.

the "Smart Bass" on TAS5825M is Biquad filters that are configured by the PPC3 GUI to add bass extension to audio output, I believe it is 5 biquad filters that are used to flatten the speaker Qts, extend the low frequency and HPF the signal

Below the blue is the SPL response of the speaker, Red is the Biquad filter applied to audio signal, and the green is the final SPL response once the Qts is flattened and the bass is extended.

the "Psycho Acoustic Bass" of TAS2781 is not true bass extension, but rather it is a algorithm that can trick the human ear into hearing lower frequencies than what are present. this algorithm works by generating harmonics of low frequency content and then removing the fundamental frequency. for example if 100Hz is played, the algorithm will generate harmonics of 200,300,400Hz and then removes the 100Hz. 

this "Psycho Acoustic Bass" is particularly useful for  speakers with a high resonant frequency, for example if you have a speaker with a 1kHz F0, then the SPL will roll off quickly below 1kHz, this can remove much of the low mids, and bass, this bass enhancer will generate harmonics of the Bass that are closer to the F0 of the speaker.

If possible you should get EVMs for both devices and test which you like better.

Regards,
Arthur