Thanks for the head up. I didn’t took the power loss in the inverter into account


According to the manufacturer, the power consumption in the Roland Cube 30 is 34W.
I don´t think the amp will exceed that figure, as long as it´s not driven into distortion.


My 13” MacBook Pro works fine with the original adapter, a 100W Waeco inverter and a sealed 7,2 Ah Lead battery. A true sine wave inverter is recommended for computers though.

Sorry for poor english grammar,
Rune

... bring along an accordion.

You used a DC load (the 12V DC vacuum cleaner) for your calculation, so the only loss in the inverter is the static loss, which is under 0.2A/2.4W, which is tiny compared to the 100W load. ;^) The discrepancy could be due to Peukert's Law. Looking at some of the run times, especially for the high power AC loads, they may also be taking into account the typical duty cycle (ratio of on vs off time for typical usage), and of course power factor as well.

Greg.

Oops, I forgot the vacuum cleaner was a DC device

Then a more appropriate equivalent to the Nord Piano/Cube 30 setup would be the 40W table lamp with a run time of 7 hours

Rune

Yeah but, even the 'better' ones these days are battery powered!

Here's a 350W Class-D amp from Roland - the SA-1000. The power consumption is just 94W, so it appears that this would be the power consumption for typical music. (presumably at maximum volume) If Roland are consistent, that would mean that the 32W power consumption spec for the CM-30 is also the typical spec. (and perhaps we can also deduce that the CM-30 is not Class-D, because the typical consumption is much closer to the maximum output power).

Greg.
p.s [off topic] Look at this - a 350W + 350W Class-D amp that's the size of an Ipod! http://www.eetimes.com/design/audio-desi...em=audio-design