Phil Starr Posted November 18, 2021 Share Posted November 18, 2021 (edited) Sorry the 'edumacation' only extended to telling you what an inverter is. Most of the commercial ones are three stage 'near sine wave' and whether they will work with your amp depends upon both the inverter and the amp. The good news is that if your amp has a switch mode power supply then you have a reasonable chance of finding something that works. If you have a Cass D lightweight amp and a friend with a caravan/camper it might be worth seeing if the amp works OK with their 'near sine wave' power supply The other battery solution is to look for a 12V amplifier. The 'bog standard' in car entertainment amps produce about 20w into 4ohms so if you can get an old car stereo with a mini jack input you could have 40W into a couple of 4ohm speakers and there are also cheap and cheerful Chinese stand alone 2x20W 12V amps around. Beyond this there are more powerful in-car amps that produce pretty much any power you want which have switch mode power supplies built in to the amp. I see @Mottlefeeder has pointed you in that direction already. It's not a bad solution if you want something cheap and only need to do this occasionally. It means you can use your usual speakers too. Worth looking at his thread on building a combo. The general problem with running off a battery is how long the charge lasts, It's not a bad idea to look to the most efficient speakers you can find. 3db of extra sensitivity is going to halve your battery use at the same sound levels. Edited November 18, 2021 by Phil Starr 2 Quote Link to comment Share on other sites More sharing options...
fretmeister Posted November 18, 2021 Author Share Posted November 18, 2021 Following on from Happy Jack's experiments with the Hotone Thunder Bass. On another forum someone has suggested an 18V drill battery. Just need to find a way to get it hooked up safely. Although at this rate I'm just going to credit card a Bari sax and have done with it! Quote Link to comment Share on other sites More sharing options...
pete.young Posted November 18, 2021 Share Posted November 18, 2021 40 minutes ago, fretmeister said: On another forum someone has suggested an 18V drill battery. Just need to find a way to get it hooked up safely. https://www.premierguitar.com/diy/pedalboard-power-supply Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted November 18, 2021 Share Posted November 18, 2021 3 hours ago, fretmeister said: Following on from Happy Jack's experiments with the Hotone Thunder Bass. On another forum someone has suggested an 18V drill battery. Just need to find a way to get it hooked up safely. Although at this rate I'm just going to credit card a Bari sax and have done with it! John @Chienmortbband I have been looking at drill batteries too. You can get higher voltages than a car battery and they are a lot lighter. I was looking for a 18-0-18 supply for a Chinese amp module and I have a couple of De Walt 18V, I never got round to trying them though. The car amps looked a simpler route. Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted November 18, 2021 Share Posted November 18, 2021 Another downside to the 'modified sine wave' invertor is that the harmonics it produces will kill small transformers - they run so hot that the thermal fuse melts. Not a problem if your FX power supply is modern and switched mode, but it is a problem if you have an older transformer based wallwart, or want to run a small mixer where the power supply is something like 15-0-15 AC. I lost several transformers before I worked out what was going on. David 1 Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted November 19, 2021 Share Posted November 19, 2021 I looked into converting the PA at Poole Town Football Club to run on 12V during an emergency. The solution I found to be best was a a leisure/Deep cycle battery powering a 12v DC to 36v DC boost converter powering a class D amp that runs on a single supply rail. Like many of these things, the boost converter and amplifier module comes from China. Amplifiers based on iCs such as TDA7498(E) and TI's TPAxxxx range work well at this voltage. Remember that there will be loss through the converter (perhaps 20%) and te amplifier will be 90% or so efficient. Also even leisure/deep cycle batteries can never be used until fully discharged. 1 Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted November 19, 2021 Share Posted November 19, 2021 I've seen people using the QTX battery PA speakers to busk, and I think there are a couple of threads on them. They're probably not the most high-end solution, but should have more oomph than the smaller battery bass combos, and they're a neat, all-in-one unit rather than having to cobble together something with modules. 1 Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted November 19, 2021 Share Posted November 19, 2021 1 minute ago, Beer of the Bass said: I've seen people using the QTX battery PA speakers to busk, and I think there are a couple of threads on them. They're probably not the most high-end solution, but should have more oomph than the smaller battery bass combos, and they're a neat, all-in-one unit rather than having to cobble together something with modules. That is probably true. As I dabble with all things electronic, the module way is the obvious one but as the saying goes “If the only tool in the box is a hammer, everything looks like a nail”. Quote Link to comment Share on other sites More sharing options...
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