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December/January 2016

by Mal Smith

Tutors’ Tutorial: The Effect of Power Fluctuations

by Mal Smith

Tutors’ Tutorial: The Effect of Power Fluctuations

Sometimes as musicians we just expect things to work and to work properly. I plug in my gear and it should just go. But, unfortunately, this is not always the case. After all the time, effort and money we spend on getting everything ready for the gig, not everything goes to plan when we get there. It worked perfectly in rehearsal or prep but not on the gig. What gives?

With a lot of modern instruments there is an electronic component and quite possibly a computer involved. As soon as these elements are added the likelihood of problems is greatly increased. Obviously we want the extra capabilities that these devices offer, but it can be very embarrassing if they fail during performance. There often seems to be an element of chance involved.

I play electronic keyboards and use Mainstage as an audio source and mixer. I love the versatility and sound quality that these devices offer but have had technical problems on several occasions. They may be minor such as patches not loading correctly, or they can be quite catastrophic, for example losing playback, or the audio card distorting. What’’s worse is it never seems to be the same thing twice.
Obviously, something is wrong, but what could it be? There are a lot of variables to consider. Incompatibilities between the software –– perhaps a plug-in isn’’t compatible with the operating system. Maybe it’’s the hardware that has an issue. Maybe it’’s both. Damn it, it worked perfectly before, what’’s different now?

It is possible that it’’s none of those things. Let’’s go back to the beginning of the signal chain. Electronic instruments need electricity. Painfully obvious, I know. We just expect that there won’’t be issues with power supply. It will always be 240 Volts at 50 Hertz. Or will it?

The power is not as clean or as consistent as we expect it to be. As the figure shows there are often peaks and troughs in the supply, which we are blissfully unaware of. We expect the black line but may get the red one.

These fluctuations can have a dramatic effect on the performance of electronics. They may not cause complete failure, maybe just a small glitch. Perhaps however these glitches will add to each other and compound any issue.

So what’’s the answer? One option is a power conditioner or UPS (Uninterruptable Power Supply). These used to be quite expensive but have reduced in price to the point where you can get one for a couple of hundred dollars or less, and they are available from computer and appliance stores.

These devices don’’t just reduce the spikes but also are able to boost up the supply when there is a trough. This means a clean and consistent supply of power to your sensitive electronics. They can do this because they include a battery (unfortunately usually quite large and heavy). Some also allow connection to your PC via USB and may have the ability to shut it down safely if there a power cut.

If you decide to go down this path then choosing the right UPS is relatively simple. Find out how much power your equipment draws. A laptop may require around 50W, the average keyboard workstation around 35W. This information is usually available in the manual or maybe on the device itself. Add the requirements together. I personally doubled this figure and then added a bit more headroom.

If you use electronics then it may be worth considering a UPS, you’’ll enjoy the music even more and it will take one variable out of the ‘’WTF is wrong now?’’ equation.

Mal Smith has been a lecturer at SAE Institute in Parnell for the past 15 years. He also mans the keys for Auckland band The Blue Jaffas. You can contact him at m.smith@sae.edu