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12v battery to power amp?


chrisd24
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Not sure if this is being posted in the right place so apologies if its wrong.

I have a 12v to 230v power inverter rated at 300w continuous and 600w peak, i thought i would see if i could power an amp from this via a 12v deep cycle battery, when i plugged the amp in it just made a horrible hum from the back and didn't allow me to power it up, the amp is only about 20w.

So was i just being optimistic when i plugged this in? or have i just done something wrong?

thanks in advance

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Probably because the inverter ain't got a lot of smoothing 'if any' on the output so you're getting a ton of 50Hz'ish' hum.
Pretty sure the inverter won't be rated suitable for audio devices. What you need is a amp that runs on 12VDC :)

Edited by KiOgon
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[quote name='KiOgon' post='798721' date='Apr 7 2010, 02:18 PM']Probably because the inverter ain't got a lot of smoothing 'if any' on the output so you're getting a ton of 50Hz hum.
Pretty sure the inverter won't be rated suitable for audio devices. What you need is a amp that runs on 12VDC :)[/quote]

Hmm seems to make sense then! i have a 12v amp but its mainly for a guitar as it sounds like a chorus of farts with a bass running through it!

so is it possible with a different type of inverter then?

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[quote name='chrisd24' post='798725' date='Apr 7 2010, 02:20 PM']Hmm seems to make sense then! i have a 12v amp but its mainly for a guitar as it sounds like a chorus of farts with a bass running through it!

so is it possible with a different type of inverter then?[/quote]
[color="#FF0000"][size=5]chorus of farts[/size][/color] That sounds like the exact fx pedal I'm looking for :)

Maybe - but you can bet your last peanut a 'audio friendly' inverter ain't gonna come cheap

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[quote name='chrisd24' post='798725' date='Apr 7 2010, 02:20 PM']Hmm seems to make sense then! i have a 12v amp but its mainly for a guitar as it sounds like a chorus of farts with a bass running through it!

so is it possible with a different type of inverter then?[/quote]

You should be fine with some kind of "pure sine wave" inverter.

Most of the cheaper inverters produce square wave output, because it is easier and cheaper to do, and a lot of kit is pretty happy with that. However, there is a significant amount of stuff that needs a decent looking sine wave, and it sounds like your amp is in that class.

The ironic thing is that a sine-wave inverter is itself somewhat like a power amp that runs off a 12V battery - you crank a small sine-wave up to 240VAC, then in your amp you transform it down to a lower AC voltage, rectifiy it, then use those volts to drive... a power amp...

As an earlier poster said, an amp that runs directly off 12V (or whatever) would be a more efficient approach (most inverters *suck* amps from 12V in a alarming fashion), but an amp that produces, say 15W into 8R, will need +/- 18V or more (although a bridged pair of chip amps running off of two 12V batteries would work pretty well, it is diy stuff rather than off-the-shelf).

I don't know if there is a bass player's version of the Roland Street Cube???

Yeah - a sine-wave inverter would probably be the easiest... Be nice to try-before-you-buy tho'.

Alan

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many thanks for all your replies.......i think what it boils down to is a pure sine wave inverter is a pretty expensive bit of kit and wouldn't really make economic sense to go down that road......if i had the know how then possibly just converting an amp at its power source to 12vdc would prob be a good shout.....but ultimately i think i need to invest in a descent battery amp!

i have tried the Roland one before in a shop about a year ago.....not sure if it was the bass i used in the shop but it sounded pretty terrible, although i have heard good things on here....also a pignose 30 or a crate taxi 50 watt battery amp i have heard good things about....and although the price tag is a bit steep at around the 200 quid mark ultimately it will make sense as my band seem intent on busking pretty much on a weekly basis now!

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