Question about: reading spec sheets, THD, clipping and speaker selection

[chriskat]

Hi All,

I have a question regarding reading the THD values in the TDA8950 amplifier spec sheet, specifically how to decide which voltage to settle with by using the BTL Power vs Voltage graph as my guide

ref Page 29, Fig 23 in: https://www.nxp.com/docs/en/data-sheet/TDA8950.pdf

My intended speaker is a Celestion BL10-100X (8 ohm, 100W RMS)

Looking at the graph, I see the line for 8 ohm THD 0.5% intersect 100W at 20V, and the line for 8 ohm THD 10% intersect 100 W at 23V.

My gut says that my circuit for 100W output should aim for the THD 0.5% value of 20V, and factor in some speaker protection for any higher THD values that may arise due to clipping.

Am I heading in the right direction?

Cheers,
Chris.
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[drMordor]

chriskat, use TPA3255 and don't worry))))

 

[abraxalito]

If you want unclipped 100W into 8R looks like you will need +/-23V rails.

 

[chriskat]

abraxalito: of course, 23V is what I should have said 🙂 Thanks for clearing that up - I take it the rule of thumb in sizing a speaker for an amp is to use the unclipped value (i.e. THD=0.5%)

drMordor: thanks for the heads up, I will definitely check that one out!