Measuring amps/power requirement for audio

[MilesDenison]

The way that I've done it (because I have way too much time on my hands..?) is sit down with my scope, build a quick and easy dummy load for the amps, and connect up my gear with an ammeter, and get a final figure.

 

[museav]

I have read this thread and understand the power will be a strange thing going to sound. I too am a light guy but get involved in the power supply side for lights,sound and video on a regular basis. I usually just ask sound what they want but have never understood how it is figured. We occasionally get in tight power limits and frequently use generators for events. I would like to have some idea how figure their needs and this thread has done nothing to clear the mystery.

One possibility is that they have used the system before in similar applications and either know what worked or not or they actually measured the current draw, in either case it is based on real world experience with that, or similar, systems and applications. Another approach is to use the information the equipment manufacturers provide and what you know about the system and application to calculate the expected requirements.

The power for 'sound' sometimes includes all the instruments and amps on stage. That aspect is often a pure guesstimate with a good 'fudge factor' for the stuff nobody thought would be there that gets added at the last minute.

Also consider the operator factor. If someone is providing numbers for a system they will be operating then they can apply how they run it to the numbers, but if there is the chance somebody will get up there and push the system to its limits and beyond then that has to be considered. With 3dB being a just noticeable difference in perceived loudness but a doubling of power, it doesn't take much to make a significant difference in the power potentially required.