Solid State Amplifier Power Output – What Determines?

[RS10]

I’m trying to understand which components and parts in a solid state power amplifier determine the power output. Let’s say we have an amplifier that outputs “x” watts per channel at 8 ohms, 20-20K, etc.

Assuming the same physical layout, circuit design, and topology - which specific parts would need to be changed/upgraded in order for the output power to be increased by say 30% above “x”? Power transformer, output transistors, main filter caps, all of the above? I understand other parts like heat sinks might need an upgrade – but trying to identify which specific components influence power output.

 

[pma]

Power supply voltage, type and number of output transistors, single or bridged operation.

As an example - for power supply 2x50V you get max. about +/- 44Vpeak output. This makes 31Vrms and this makes 240W/4ohm or 120W/8ohm. Just very roughly, because transformer VA etc. play its game. These numbers would be close to achievable maximum. In bridged mode, you get in theory 4x more power. However, double current load so the real power would be lower.

 

[sergeauckland]

With a SS amplifier, output power is determined by output voltage which in turn is determined by the DC supply. You need enough DC volts to swing the whole AC peak to peak output voltage plus a few extra volts for the minimum drop across the output transistors.

Apart from that, everything else is pretty much the same in terms of topology between a low powered amplifier and a high powered one. Clearly, the output transistors used have to be able to stand the higher voltage and higher currents of a bigger amplifier, and the driver stage have to provide enough drive for the output stage, but if you look at the circuit diagram of a, say, 30 watt amp and a 100 watt amp, without the component and voltage values marked, you wouldn't easily be able to tell which is which. Even a much higher output amp, like 200 watts-500 watts is likely to be much the same, except that the outputs may be paralleled to provide enough current.

S

 

[solderdude]

As has been mentioned above... it isn't that simple because parts need to be changed, some parts need to have higher voltage ratings and or settings.
An all that for 30% more power which is 1.1dB more headroom.

To get a meaningful increase in power you need LOTS more power, not 30% more.
Consider bridging (but the speaker impedance needs to be double the minimum rating the amp has now) or just buy another amp.

1 dB is not worth the hassle.

 

[RS10]

Thanks all for your replies. The 30% increase figure was hypothetical simply for a reference point. I do not plan to build or modify an amplifier, only interested in learning. Thanks again !