~How much power to expect from TDA7498 with 20v supply/8 ohm and 24v supply 15 ohms?

[freddi]

due to driver and cost restrictions my upcoming boombox will have its 8 ohm woofer driven by a 20 volt tool battery supply mono TDA7498 and its mid-treble 16 ohm drivers with 24 volt tool battery 2.0 TDA7498.

How much reasonably clean power should I expect with each of those amp/speaker combos?

 

[ejp]

Well 20*20/8 = 50 and 24*24/16 = 36, but I would do it the other way round, 24V into the 8 ohm woofer, for 72W, and 20V into the 16 ohm tweeter, which needs far less power, for 25W.

These are all absolute maximum values. How much of that you can get clean depends on the circuits,

 

[Hiten]

Not 16 ohms load but it does have 8 ohms load power measurements before clipping. Will give you just broad idea of poer. Board is stereo and may be different. Power measurement result at different power supply is at around 12.55 time.

 

[jan.didden]

But the supply is 20V unipolar, so the max output would be something like 18V pk-pk or 9V pk.
Which gives 9 * 0.7 RMS or 6.3*6.3/8=5W on a good day.

Jan

 

[freddi]

Sound like my big box will be seriously underpowered. Fosi specs the TDA7498 woofer amp only up to 24V - I don't know if that means a fully charged 24v tool battery is too much for it - or not.

The 2 channel amp is rated to 35V supply.

I could parallel the 16 ohm Alphalite 6B and run those and the piezo from a mono amp - tho the amps in the pic below are already purchased:

 

[uriy-ch]

How much reasonably clean power should I expect with each of those amp/speaker combos?

According to this graph, with 20V supply and 8 Ohm load, you can expect 40W/2=20W power with 1% signal distortion. With 24V supply and 16 Ohm load, you can expect 60W/4=15W with 1% signal distortion.

 

[jan.didden]

This is physically impossible unless the 20V is bipolar +/-20V.
The OP stated 'a 20V battery' which is unipolar of course.
A quick calculation will show it as I did above in post #4.
For 4 ohm, you might get to 10W, but barely.

Jan

 

[uriy-ch]

This is physically impossible unless the 20V is bipolar +/-20V.

The chip has a bridged output. For fun, open the datasheet and see what it can do.

 

[jan.didden]

OK, yes if you bridge it, you can get 4x power.

Jan

 

[freddi]

Oh - hopefully I can get ~20W into the woofer - with a 40 liter box, 2pi and 450uF series capacitor: