Powering amps with inverters?

Brian McGaughey · Post by **Brian McGaughey** » 2 Jul 2007 8:29 pm

I've been "volunteered" to figure out how to power a small electric combo on the back of a float in a parade. Does anyone have experience at powering amps in a setting like this?

I've see two types of 12 volt dc to 110 ac inverters. One a modified filtered sine wave (code for square wave?) and one a true sine wave. Has anyone had experience running a guitar amp with either type? I don't want to damage anything.

Would 1000 watts run a small guitar and small bass amp? I see my NV 112 draws 200 watts.

Other alternatives I've thought of include generator (too loud), battery powered guitar amps (no have), or going acoustic (leaves bass player out).

Any ideas would be most appreciated. Thanks!

Brian

Jonathan Cullifer · Post by **Jonathan Cullifer** » 2 Jul 2007 9:34 pm

The "Modified Square Wave" inverter won't damage anything, but you'll probably wind up with a lot of noise and artifacts in your signal. The true sine wave inverter should produce an output identical to commercial power. For audio applications, that's probably your best bet. Just make sure you have enough battery to handle everything, even as the voltage deteriorates.

Also, check the power of the bass amp. It's easy to eat up a lot of power running anything bass. Any low powered guitar and steel amps should be fine.

Dave Potter · Post by **Dave Potter** » 3 Jul 2007 2:59 am

All the parades I've attended in my life have had a pretty loud ambient sound level from the crowds watching the parade. I can't remember any where everything's been quiet. If this one will be anything like that, I'd give a little more thought to the generator idea - some of them are pretty quiet these days, I think, again, in terms relative to a loud external noise environment. And you might be able to place it somewhere on the float where some of its sound would be muffled by location. You might do a little internet research on generator specs, power output, engine sound level, etc.

It doesn't seem to me that a totally-acoustic approach would work, if it's a noisy parade - the instruments wouldn't be heard. And the 12V->inverter route looks dicey. To get the power you'd need for as long as you likely need it, assuming no charging to the batteries, it would take quite a few of them, I'd guess, without doing the math. In my RV, there are 4 deep-cycle golf cart batteries for house power - a pretty hefty battery bank. Even when they're fully charged, I can run them down with a couple of hours of TV, microwaving, and lights.

Disclaimer: Free advice is worth every penny you pay for it.

Mike Wheeler · Post by **Mike Wheeler** » 3 Jul 2007 3:50 am

I agree with the generator route. I've seen and heard some of the Honda models, and they are surprisingly quiet. I'd go for around 1500 watts for a modest sized bass amp and guitar amp.

I'd calculate the size needed by adding all the wattages up, and then adding 50% more...then rent one that meets or exceeds that wattage rating. The closer you get to using the generator's maximum output, the noisier the A/C will be. That's what the extra 50% more wattage is for.

John Daugherty · Post by **John Daugherty** » 3 Jul 2007 4:21 am

The inverter will do the job if you can connect it to the battery in the vehicle that is towing the float (assuming the alternator is at least an 80 amp model). Mount the inverter close to the battery so you won't have to run long, huge battery cables. Run the AC extension cord from the inverter to the amps.
Try this arrangement with the engine running to see if it affects engine performance. Make sure the engine is running before you connect the AC cord, so you won't run down the battery.

Brian McGaughey · Post by **Brian McGaughey** » 3 Jul 2007 4:56 am

Wow guys, thanks! All great info.

One of the things I failed to mention is that the "float" is actually a flat bed being towed by a pickup truck. I had planned on wiring the inverter directly to the trucks battery. I had imagined something like John explained if I were to use an inverter.

I hadn't considered the ambient noise level. It will be loud, Dave. This leads me to imagine that the noise from a generator would be easily overcome since the band will be a level to be heard over the crowd anyway. I just have yet to hear one of these newer Honda generators. I think of my 60 or 80 amp or so Generac model and it's plain obnoxious when it runs.

Mike, thanks for your tip on sizing the generator. And Jonathon, you saved me wasting time on using a modified sine wave inverter. I figured they'd be noisy in this setting.

I think what I'll do is see what the rental store offers. It looks like either a quiet generator or a true sine wave inverter will work. I'd imagine the store would be more likely to have the generator, a newer less noisy one we'll see! I think I'm leaning that way.

Thanks again.

Brian

Ken Fox · Post by **Ken Fox** » 3 Jul 2007 5:06 am

My Honda RV generator is so quiet you can stand next to it and have a conversation. Look at the specs and you will see the one for RV use are quieter than the other portable Honda generators. A 3000 watt is around $2100.00 new. I got mine off Cragslist at $1100.00.

Mine is like this one on eBay:

http://cgi.ebay.com/2006-USED-HONDA-EU1 ... dZViewItem

Ken Fox · Post by **Ken Fox** » 3 Jul 2007 5:11 am

http://www.wisesales.com/SuperQuiet.html

Here is 1000 watt model that sold on eBay:

http://cgi.ebay.com/BRAND-NEW-HONDA-EU1 ... dZViewItem

Brian McGaughey · Post by **Brian McGaughey** » 3 Jul 2007 3:16 pm

Thank you, Ken. A Honda EU series generator is exactly what we need...

Brian

Robert Leaman · Post by **Robert Leaman** » 3 Jul 2007 3:49 pm

Why don't you buy a decent muffler for your Generac?

Try your friendly RV supply store. They'll do anything for money.

They are available and no harm is done. I put one on my 10kVA Generac so it doesn't drive the neighbours crazy when power fails here in mountains.

Then, you can have the best of both worlds.

Dave Potter · Post by **Dave Potter** » 3 Jul 2007 4:48 pm

Brian McGaughey wrote:One of the things I failed to mention is that the "float" is actually a flat bed being towed by a pickup truck. I had planned on wiring the inverter directly to the trucks battery. I had imagined something like John explained if I were to use an inverter.

I thought that would probably be the arrangement. Long runs of heavy gauge copper wire are bulky and expensive.

I hadn't considered the ambient noise level. It will be loud, Dave. This leads me to imagine that the noise from a generator would be easily overcome since the band will be a level to be heard over the crowd anyway. I just have yet to hear one of these newer Honda generators. I think of my 60 or 80 amp or so Generac model and it's plain obnoxious when it runs.

Yes, some gensets can be loud. The one in our RV is a 7.5KW diesel Generac unit. Being a diesel, it's built for longevity, but it's louder than what you'd be looking for. I think many of the current crop of gas-powered gensets nowadays are much quieter. And, to my amazement, the 35KW "whole-house" generator I recently had installed for my home isn't all that loud, considering it's output.

I think I'd still be looking at something in the gas-powered genset lineup.

Dave Potter · Post by **Dave Potter** » 3 Jul 2007 4:57 pm

- Unintended - pls disregard.

Brian McGaughey · Post by **Brian McGaughey** » 3 Jul 2007 8:42 pm

I like that idea, Robert. I assume that better quality, quieter mufflers are available to improve the performance over the stock mufflers. Yours was quieter, even though the old one wasn't worn out, is that right?

If I can get that Generac of mine quieter, that'll be the answer.

Thanks again for sharing your ideas everyone. What a great resource.

Brian

John Daugherty · Post by **John Daugherty** » 4 Jul 2007 3:37 am

Brian, if you are serious about owning a quiet generator, I think you would be wise to buy a 1kw-2kw, quiet model, rather than invest in a muffler. Honda ATV mufflers start at $200. I imagine their other mufflers are in the same price range.
You may find what you want at "Northern Equipment Co." They have a web site.
Sears also stocks a small quiet generator.

Donny Hinson · Post by **Donny Hinson** » 4 Jul 2007 4:50 am

Since your float is being towed, it's usually advisable to have the generator in the tow vehicle (pickup bed). For most modern generators, noise shouldn't be a problem, and you can reduce the noise transferred to the pickup body by having about 6" of dirt or sand in the bed. Also, the rather poorly regulated output of most small portable generators means you should use just "basic" amplifiers. ("Modeling" amps or other digital devices may not operate properly.)

Also, for safety's sake, remember to carry two fire extinguishers...one on the float, and one in the tow vehicle.

The Steel Guitar Forum

Powering amps with inverters?

Powering amps with inverters?

Aux. Power