Output

[tallnutt]

Hi,

I have this TPA3116 board. Why are the speaker outputs both at 12V relative to the ground input? I've done some gain and input circuit mods but this isn't normal? Running it at 24V with a switching power supply. Otherwise it works well but just noticed this. The + and - speaker outputs are mV as you would expect, but both +12 relative to ground and input voltage!

any ideas??

Thanks,

Thei

 

[tallnutt]

N.B. The negative input voltage is 0V relative to ground, so it's not the supply.

 

[Khron]

Class-D amplifiers are basically modulated synchronous buck converters.

A single-supply amp, powered at 24v, will have a 50% duty cycle at idle, and guess what 50% of 24v works out as 😉

 

[tallnutt]

Class-D amplifiers are basically modulated synchronous buck converters.

A single-supply amp, powered at 24v, will have a 50% duty cycle at idle, and guess what 50% of 24v works out as 😉

Thanks. I thought it might be something like that, I only noticed when I tried to use my grounded scope probe on it.

 

[tallnutt]

So If I use a +/- 12 V supply, the output will be zero relative to ground?

 

[brig001]

So If I use a +/- 12 V supply, the output will be zero relative to ground?

Yes, but the inputs will have to be referenced to -12V which will cause problems if the 0V is grounded and the input source is grounded

Brian

 

[bucks bunny]

Yes, but the inputs will have to be referenced to -12V which will cause problems if the 0V is grounded and the input source is grounded

Brian

These amps are single supplied with outputs biased at half supply voltage. Negative supplies do not make sense here.

 

[brig001]

These amps are single supplied with outputs biased at half supply voltage. Negative supplies do not make sense here.

Exactly

 

[JMFahey]

If amplifier is single supply you either have an output coupling capacitor or output is bridged, which is the case here.