generators and Digital Amps

[djmatthill]

Hello

I'm just after your thoughts on a question please if I may....

 

A friend of mine is planning to use a number of Beringher I Nuke digital power amps at an outdoor event next month. The whole PA system will be driven using a

generator.

 

Have any of you had any issues using the new breed of Switch Mode Power supplied digital amps on Cheap/normal Diesel Gennys..

We are talking HSS style 2.5kva sets ?

 

He has a Studiomaster (sound lab branded) powered mixer that refuses to work properly on gen sets ?

 

 

Matt

[chelgrian]

Have any of you had any issues using the new breed of Switch Mode Power supplied digital amps on Cheap/normal Diesel Gennys..

We are talking HSS style 2.5kva sets ?

 

Such sets will probably not have automatic voltage regulation which is essential for running audio gear. There are some relatively cheap Honda sets which have appropriate outputs. Note sure about hiring small suitable sets.

[david.elsbury]

Personally I would not use any small (HSS style) gensets without AVR in them. Honda's are the bare minumum of a small generator that I would trust my, and other's valuable equipment to. Anything else is just a waiting game till it dies. If a job's worth doing, it's worth doing properly and without killing gear! :)

 

David

[BigYinUK]

+1 Absolutely agree. Anything with a switched mode power supply in it is going to be very sensitive to a dirty supply. Most of the non AVR gen sets I've used, the mains is so wobbly that you can see it on a light bulb. Certain death for a class D amp and a lot of digital electronics.

 

Regards

[timsabre]

+1 Absolutely agree. Anything with a switched mode power supply in it is going to be very sensitive to a dirty supply. Most of the non AVR gen sets I've used, the mains is so wobbly that you can see it on a light bulb. Certain death for a class D amp and a lot of digital electronics.

 

This is not so, class D amps and switching power supplies are much less sensitive to a dirty supply than a transformer supply, because the switcher will adjust to changing input voltages. That's how come you can get power supplies that work from 90V-260V.

 

The big danger is if your genny goes over the max voltage rating of the device, which it could well do. That will kill it.

[itiba]

If you go down the route of using these small gennies then I'd consider using an On-line UPS which can act a bit like a buffer and adsorb any nasty things getting through. Whether it's affordable to get one and whether the power supply from the gennie is 'clean' enough to power the UPS is another question!

 

 

You mention a number of amps, will these be run from the same source or will you have multiple generators?

 

[Stuart91]

My general advice would be not to use gennies from construction hire companies. They are usually only powering things like site lighting and power tools which are on the whole very tolerant of dodgy supplies. Also, whilst some companies are better than others, many just fling them out and in again. I've seen some sets arrive at events that have clearly come straight from a building site.

 

You should hopefully be able to find an events-focussed power company in your local area - ask for recommendations.

[emsgeorge]

Just be aware that most UPS's don't actually like some of the smaller 'clean' generators.

 

We have a small Honda eu10i and also a Honda eu26i - both are a nice smooth supply, and are inverter type generators.

 

We had a ups in line, to ensure if it ran out of fuel, the supply wouldn't be interrupted.

 

The UPS simply didn't like the supply, at all, and kept switching to battery, then to mains, then back to battery, constantly.

 

we replaced the ups, thinking it was at fault. Not so, as the replacement (different brand) did it as well.

 

After trying 3 different branded ones, we gave up. So even the smoothest of outputs can sometimes not play will with other kit.

[timsabre]

We have a small Honda eu10i and also a Honda eu26i - both are a nice smooth supply, and are inverter type generators.

 

A generator with inverter output recreates the AC mains waveform from DC produced by the generator. That's basically like running a UPS off the output of another UPS and it's not surprising that the UPS's mains fail detection didn't know what to do with it. The output waveform of an inverter is often very crude AC and nothing like the nice sinewave of proper mains.

 

(this shouldn't affect a normal load though)

[Stuart91]

We had a similar problem with a UPS - we were using it inline with an older digital desk that would take 2 mins to boot up if there was a power outage. The problem seemed to be that the UPS had a very tight tolerance for voltage drop. The generator seemed to stay within 220-230v but the UPS was moving over onto battery as soon as it dropped below 230. In theory it was possible to change the settings but this involved installing drivers on a PC and hooking up via RS232. We ended up upgrading desks so the point became moot.

 

I'm not sure if more modern UPS units are any easier to tinker with.

[kerry davies]

At the risk of cutting this short has the OP not answered his own question in his original question?

Have any of you had any issues using the new breed of Switch Mode Power supplied digital amps on Cheap/normal Diesel Gennys.......He has a Studiomaster (sound lab branded) powered mixer that refuses to work properly on gen sets ?

If a Studiomaster don't work why bother risking more expensive kit?

[Stuart91]

The other thing that people often fail to take into account is the nature of the load imposed upon a generator by power amps. The energy drawn is pretty much proportional to the intensity of the music, so silence followed by a sharp loud passage can mean the genset needs to swing from idle to full output almost instantaneously. So having only a single power amp running subs off a small generator is a recipe for trouble. Sometimes adding a dummy load can help - an old parcan or heater that will present a steady load and lessen the disparity somewhat.

[TonyMitchell]

planning to use a number of Beringher I Nuke digital power amps at an outdoor event next month. The whole PA system will be driven using a

generator.

 

 

How many is "a number"? (in context, I imagine it's more than one or two...)

 

 

We are talking HSS style 2.5kva sets ?

 

 

How many were you planning to run off a 2.5kva set?

 

Are they all going to be in the same place, or dotted around the site?

 

 

If the former, why not hire the right tool for the job, suitably sized & AVR'd, that won't fart & stop on an unsteady load?

[Oldradiohand]

Having seen the results of putting dimmed mains into a Mac500 I wouldn't want to put anything other than a clean sine wave into a switched mode supply!

[timsabre]

Mac500s had transformers didn't they? Transformers can get very hot with a non sinewave supply as it's easy to get a dc offset.

 

Switch mode supplies generally cope with being dimmed (just look at all the mains dimmable led lamps) but spikes on the switching edges can cause overvoltage failure.