Clipping in relation to power output and voltage rail

[Adrian_D 520]

Just thought this a good video of what happens when we get gain happy and want more power than the amp can output.

You can see the blue line, that is the amplifier's voltage rail. The yellow sine wave is the output voltage

The more we increase the gain (or the input voltage), the higher the output voltage and the lower the rail voltage. Voltage rail will never be stable, because of the design of the power supplies and because of the drop in battery voltage. At some point the peak output voltage will match the rail voltage. That is the maximum output. If we try to increase the gain or apply more input voltage, the output voltage cannot increase (it was equal to the rail voltage) and in consequence it starts to clip.

Battery voltage: 14.4v (before the test) down to 9v (minimum)

Voltage rail: 177v (before the test) down to 92.6v (minimum)

Peak output voltage: 92v

RMS output voltage: 92*0.707=65v

Here is the video, shot by a friend

This was tested on a 1ohm resistive load.

[cobra93 47]

Great video!!

I never considered the input voltage dropping as the output voltage increased.

I realize this happens, just dismissed it I guess.

[Adrian_D 520]

Great video!!

I never considered the input voltage dropping as the output voltage increased.

I realize this happens, just dismissed it I guess.

The voltage which drops is the voltage rail ie the power supply output. Same thing happens when the load gets lower and lower in impedance. If the power supply would be ideal, power output would double with each halfing of the load.

[Julian 641]

Great video, Huge lighter too!

what amp is that?

Edit: looks like an older D9 or an AQ 3500

[Adrian_D 520]

DB drive 7500

"slightly" modded and doing some other mods to improve reliability

[Julian 641]

DB drive 7500

"slightly" modded and doing some other mods to improve reliability

Ooh like what?

similar looking board layout as the AQ 3500

[Adrian_D 520]

Extra windings on the transformer for higher voltage rail for now.

Board layout is actually very similar to the DD Z2LV