Power for amp at outdoor gig

[agedhorse]

But the actual power source is one or more batteries, which are at 12VDC, so the power calculation needs to be done for that voltage. The line voltage used by the amplification is secondary and will only be applicable if the inverter is able to supply 120VAC under load.

I don’t think you are understanding how this works.

If a bass amp is rated to draw 3 amps at 1/8 power (fairly large amp), the sizing for battery life is based on this long term average by multiplying the current by the line voltage giving 360 watts, then multiplying by the inverter efficiency of say 80% or 420 watts.

Now you look at the battery capacity. Multiply the AH by the voltage and you get watt-hours. Say your battery is 12V and 100 AH, that would be 1200 Watt-hours but a standard lead acid car battery has discharge limits of about 50% which gives you 600 watt-hours of capacity.

Now, divide the capacity by the load and you end up with the hours of run time, or in this case 600WH/420W or about an hour and a half.

For inverter SIZING, it must be capable of supporting the dynamic load which includes the short term peak currents. A good rule of thumb for class D bass amps is roughly 50% of the audio power, converted back to AC line current. So if the amp was rated at 800 watts into the load being driven, that would be 400 watts, which is the minimum the inverter would need to be rated for independent of the battery side of things.

 

[DanGroove]

Has anyone used a power inverter with a car battery to power a bass or guitar amp? If so how long will the battery last, ac power is not available. Load in and out is not an issue so full stack with deep cycle battery is ok. Generator is possible but not preferred. Anyone with practical experience? Thanks

I used to use a setup like this with the marching band in high school back in 1992. Unfortunately I can't speak to expected run time beyond a football halftime show.

 

[seamonkey]

I powered PA system is also a great option
Battery-powered Portable PA Systems | Sweetwater
Get yourself a good preamp to get your tone, and try a few of these.

Another option is many of the cordless tool makers now make inverters that use their tool batteries. Ryobi, Dewalt, Milwaukee, ... Many are pure sine wave inverters. It depends on your amp if pure sine wave is needed. Many SMPS amps can work fine on modified sine waves.

There are many reviews on youtube of all the options. The batteries come with several year warranties, quick chargers, and they're lightweight. The nice thing is that spare batteries are easy to come by, they are sold everywhere and just click in and out.

 

[Sushi Box FX]

I haven't seen this mentioned so I'll chime in to say, make sure you at the very least run surge protectors (power conditioners are better) for everything you plug into a generator. My first amp repair job as a tech during college was for a band that played an outdoor gig plugged straight into a generator and fried all of their amps I'm sure some generators are better than others, but the voltage coming off them isn't clean and can surge sometimes.

 

[Slough Feg Bass]

if you have a small combo amp, and guitar has small solid state amp, you will be fine running off the car for a an hour or two, I've done it, no problem.

However, add the PA in there, maybe a couple of lights, and you better just get the Honda generator and be done with it. One of the best investments I've made, one of the EU2000 models. we can do shows anywhere, with no worries at all about power, even with tube amps, small PA, some lighting, and everyone charging their iPhones.

 

[Flog]

Pick up a "kill a watt" meter or something similar to determine how many watts your amp is using. (kind of fun to plug in to various household appliances too...) I've got solar panels charging LiFePo4 batteries at my house (weird hobby).
Would agree with other posters that a small, quite generator would be your best bet.

 

[dbase]

I used two group 31 batteries in my boat with an 1800 watt inverter. Would run the lights, water system, coffee maker, tv for two days. Also would start and run a 10,000 btu central a/c unit but not very long. Once the voltage drops to 11 volts it would start beeping and then shutdown. I'm thinking it would be fine for a bass amp for a gig. That's a lot of weight to lug.[/QUOTE]

 

[agedhorse]

I haven't seen this mentioned so I'll chime in to say, make sure you at the very least run surge protectors (power conditioners are better) for everything you plug into a generator. My first amp repair job as a tech during college was for a band that played an outdoor gig plugged straight into a generator and fried all of their amps I'm sure some generators are better than others, but the voltage coming off them isn't clean and can surge sometimes.

Well, if the surge is large enough to damage an amp that carries an agency safety certification, than a typical "power conditioner" or "surge protector" isn't going to be of any meaningful improvement. If you understand what these devices are and how they work. There are devices that can help, but they are almost as expensive as the generator itself.

Inverter generators, which are PSW type, are pretty darn clean, and most generators these days are not too bad. The biggest issue is outright failure of the AVR's and the inability of the generators with low rotating mass to regulate voltage and frequency well with highly dynamic loads

 

[Plain Old Barry]

The Honda EU-series of inverter generators are the way to go -- they are "quietized" in addition to having good stable sine-wave output. They've been updated, so the numbers aren't exactly what they used to be, but basically they offer 1000, 2000 and 3000 watt models in manageable sizes. I wouldn't get anything smaller than the 2K one, but you're in a better position to calculate what your total load would be -- add up the potential power consumption needs of everything that's going to be plugged into the genny, and then allow yourself some margin. And Was is right, forget about the Eco mode on the engine.

I own two Honda eu2000i's, the newer versions are 2200. They're about 50 pounds, all up, super easy to handle.

They're GREAT! Both of mine have over 700 hours each on them with only 13 oz. oil changes every 50 hours and a new plug every 200. I can tie them together in parallel for 4000 watts of clean 120v power to run RV A/C. It's worth noting that (2) paralleled 2000's are 50 pounds lighter than (1) 3000, with more output. There are examples of eu2000i's on food vendor wagons with thousands of hours of reliability, still going.

Along with another repeat of Eco mode OFF for dynamic loads like music, facing the exhaust pipe away from the most noise sensitive area makes them seem even quieter, as that's where most of the noise comes from. You can put a vehicle or some other barrier in front of them for even more noise reduction. They suck cooling air in the front and blow it out the back around the exhaust, so you can protect them from rain or hot sun simply by placing a 1/4 sheet of plywood over them or putting them under a lowered pickup tailgate.

If you call around to local power equipment vendors and rental houses, you may be able to rent one. They're super simple to operate. They even shut themselves down if the oil gets low, and resetting an overload is as simple as turning the unit off and back on.

 

[KohanMike]

I put together this battery and inverter for my Carvin MB15 Combo D 200/250w amp with matching 115MBE that is very small, light and runs for about 6 hours or more. A Wagan EL2600 Elite Pro 200W Pure Sine Inverter for $55 from Amazon. It has two a/c outlets and one USB. With a Universal UB1280 AGM 12v 8Ah battery from my local hardware store that measures 6.25" wide x 8" tall x 2.75" deep, weighs 6.4 lbs for $38 plus charger for $30 from a local audio parts stores. I put together the wires and Velcro straps. This photo should show you how compact it is.

 

[agedhorse]

So, that's 100 watt-hours which is going to give a pretty short run time under many bass guitar applications when you are actually playing.

The MB-200 calculates to 25 watts average power consumption while playing, so accounting for inverter inefficiency and discharge depth, I would expect about 2 - 2.5 hours of playing time with THAT amp. The MB-200 is an extraordinarily efficient SMPS/class D amp however.

 

[Rip Van Dan]

The Honda EU-series of inverter generators are the way to go -- they are "quietized" in addition to having good stable sine-wave output. They've been updated, so the numbers aren't exactly what they used to be, but basically they offer 1000, 2000 and 3000 watt models in manageable sizes. I wouldn't get anything smaller than the 2K one, but you're in a better position to calculate what your total load would be -- add up the potential power consumption needs of everything that's going to be plugged into the genny, and then allow yourself some margin. And Was is right, forget about the Eco mode on the engine.

FYI if you use a Honda generator - speaking from experience - you MUST use alcohol-free (ethanol-free) gas to run them. Normal gas stations sell gas that is 10% ethanol. You can get ethanol-free gas in various brands in 1-gallon sizes but price is huge. Lowes and Home Depot sell a brand that is $29.99 for a gallon can. I saw it one place at just $12.99 and another for $32.99. Then I found a gas station in a town about 30-miles away where they sell racing fuel and have ethanol-free at the pump. It was $3.29 a gallon at their pump when regular gas was $2.59 a gallon. I have 5 gallons of it set aside for the next outage.

If you forget to not only empty the gas tank when you're done, but also to drain the carburetor with its little drain tube in a Honda generator, the residual alcohol will evaporate and turn to gunk in your carburetor and won't start. You can't use carburetor cleaner in it because it will melt some of the polymer parts. So you have to have the carburetor removed, cleaned, and rebuilt (new jets put in) before it will work again. Was a tough lesson to learn. It is nice and quiet and we used it twice with no problem and then, after putting in regular gas, tried to start it a week later to no avail. We had borrowed this Honda EU2200i and had to fix it before returning it. Now we have a Craftsman one that can use regular gas, but have used the ethanol-free because I already have it.

We have a lot of power outages on our side of the hill (mountain if you're east of the Mississippi) in Washington state. We get a lot of rain and if we get heavy winds, trees start falling and knocking out electrical lines. That also means we don't have any water because we have a 300-ft deep well with submersible pump that is electrical. I keep about 15-gallons of water on-hand for cooking and drinking and use pond-water (we have 2 ponds) to flush the toilet (that's inconvenient!). The generator though allows us to use our refrigerator and powers the internet and TV.

So...don't put regular gas in your new generator!

 

[Redbrangus]

FYI if you use a Honda generator - speaking from experience - you MUST use alcohol-free (ethanol-free) gas to run them. Normal gas stations sell gas that is 10% ethanol. You can get ethanol-free gas in various brands in 1-gallon sizes but price is huge. Lowes and Home Depot sell a brand that is $29.99 for a gallon can. I saw it one place at just $12.99 and another for $32.99. Then I found a gas station in a town about 30-miles away where they sell racing fuel and have ethanol-free at the pump. It was $3.29 a gallon at their pump when regular gas was $2.59 a gallon. I have 5 gallons of it set aside for the next outage.

If you forget to not only empty the gas tank when you're done, but also to drain the carburetor with its little drain tube in a Honda generator, the residual alcohol will evaporate and turn to gunk in your carburetor and won't start. You can't use carburetor cleaner in it because it will melt some of the polymer parts. So you have to have the carburetor removed, cleaned, and rebuilt (new jets put in) before it will work again. Was a tough lesson to learn. It is nice and quiet and we used it twice with no problem and then, after putting in regular gas, tried to start it a week later to no avail. We had borrowed this Honda EU2200i and had to fix it before returning it. Now we have a Craftsman one that can use regular gas, but have used the ethanol-free because I already have it.

We have a lot of power outages on our side of the hill (mountain if you're east of the Mississippi) in Washington state. We get a lot of rain and if we get heavy winds, trees start falling and knocking out electrical lines. That also means we don't have any water because we have a 300-ft deep well with submersible pump that is electrical. I keep about 15-gallons of water on-hand for cooking and drinking and use pond-water (we have 2 ponds) to flush the toilet (that's inconvenient!). The generator though allows us to use our refrigerator and powers the internet and TV.

So...don't put regular gas in your new generator!

The great thing about rentals is you don't have to give a dang -- they just have to get you through that one gig. I actually had never heard that about the fuel -- and I've put more than a few gallons of regular old gas from the convenience store in 'em, but as I say...they were rentals. I bite the bullet and get store-bought, ethanol-free pre-mixed fuel for my 2-stroke chain saw and string trimmer, but I don't use more than a quart or two in a year, so the cost is easy to swallow -- and I absolutely hate working on small gas engines any more, so good fuel is a cheap enough investment.

Our recent electrical trauma here in Texas had me thinking (again) about buying a little putt-putt for backup at the house -- but then I got to thinking about having yet another internal combustion engine to keep maintained, and how hard it is to keep fresh fuel around for an engine that's seldom run, and I decided against it. A buddy just put in a 10Kw Genrac that runs on natural gas for backup at his house -- he was probably feeling pretty good about that decision during the Time of Trouble last month.

 

[Plain Old Barry]

FYI if you use a Honda generator - speaking from experience - you MUST use alcohol-free (ethanol-free) gas to run them.

So...don't put regular gas in your new generator!

That depends...

My 700+ hour pair run regular E10 gas all summer, as they get used nearly every weekend with a race team. No issues at all in over 10 years... I don't drain the carb every week. All the food truck folks run regular pump gas, too, as they use the generators 5-6 days a week.

I do switch to ethanol free gas at the end of the racing season, specifically 5 gallon pails of VP C9 or VP SEF, where it gets filled and stored full for the off-season. I do the same for off-season storage of my mowers and snowblower. Both of those machines are 21 years old, with the original carbs.

Your advice about draining the carb for sits of any duration is spot on, but the machine is fine with FRESH E10, just like the manual says. E10 can go bad in as little as 60 days, which is what causes most issues when people leave it in small engines. 1oz./gal of Seafoam doesn't hurt, either.

The gas to definitely not use is Avgas, as it's leaded. The tiny jets tend to get clogged with lead, especially when the machines run for extended low speeds in Eco mode. Be careful with race gas, too, as many formulations are still leaded.

 

[Wasnex]

FYI if you use a Honda generator - speaking from experience - you MUST use alcohol-free (ethanol-free) gas to run them. Normal gas stations sell gas that is 10% ethanol. You can get ethanol-free gas in various brands in 1-gallon sizes but price is huge. Lowes and Home Depot sell a brand that is $29.99 for a gallon can. I saw it one place at just $12.99 and another for $32.99. Then I found a gas station in a town about 30-miles away where they sell racing fuel and have ethanol-free at the pump. It was $3.29 a gallon at their pump when regular gas was $2.59 a gallon. I have 5 gallons of it set aside for the next outage.

If you forget to not only empty the gas tank when you're done, but also to drain the carburetor with its little drain tube in a Honda generator, the residual alcohol will evaporate and turn to gunk in your carburetor and won't start. You can't use carburetor cleaner in it because it will melt some of the polymer parts. So you have to have the carburetor removed, cleaned, and rebuilt (new jets put in) before it will work again. Was a tough lesson to learn. It is nice and quiet and we used it twice with no problem and then, after putting in regular gas, tried to start it a week later to no avail. We had borrowed this Honda EU2200i and had to fix it before returning it. Now we have a Craftsman one that can use regular gas, but have used the ethanol-free because I already have it.

We have a lot of power outages on our side of the hill (mountain if you're east of the Mississippi) in Washington state. We get a lot of rain and if we get heavy winds, trees start falling and knocking out electrical lines. That also means we don't have any water because we have a 300-ft deep well with submersible pump that is electrical. I keep about 15-gallons of water on-hand for cooking and drinking and use pond-water (we have 2 ponds) to flush the toilet (that's inconvenient!). The generator though allows us to use our refrigerator and powers the internet and TV.

So...don't put regular gas in your new generator!

This additive has worked well for stabilizing ethanol in my motorcycles: [Invalid or Expired Link Removed]

That being said, when I can, I ran pure gas which is not that hard to find in my state. However, finding a gas pump with a separate hose for all grades of gas is not easy. So if the bike will sit after a fill up, I add a little Star Tron.

The bikes sit over the long Mid-West winter and start up with no problems in the spring. This has been true with pure gas and ethanol.

 

[Nephilymbass]

Has anyone used a power inverter with a car battery to power a bass or guitar amp? If so how long will the battery last, ac power is not available. Load in and out is not an issue so full stack with deep cycle battery is ok. Generator is possible but not preferred. Anyone with practical experience? Thanks

There are specific products that do this in one unit without any mad scientist electrical stuff, they’ve been around for decades. I played bass guitar in the pit for marching band my senior year (1999) and used one. It was a swing themed show. We had a Duracell one. I used a solid state peavey rig. It was basically similar weight as a car battery, so not light enough that I would take it hiking hauling it a bass and an amp in a backpack but we had the entire setup on a cart with big wheels that rolled easily even on grass. Great solution if you go camping and aren’t hiking to your campsite And plan on a little camp jam. Or you are playing with an acoustic band but want to play bass amplified.

There a lot of different ones. Just make sure the one you choose will handle the power requirements of your amp.

pjb also made a little bass combo amp that could powered with a what was basically a motorcycle battery. And they have some newer amps that basically use the same power supply as most laptops so I’m sure if someone who knows what they are doing could make an external laptop power supply to run them.

 

[sawzalot]

Every outdoor gig I've done we used a generator. My advice: keep it simple and use a generator; there are enough gremlins in the machine at outdoor gigs as it is.

 

[Drummerboy2]

Has anyone used a power inverter with a car battery to power a bass or guitar amp? If so how long will the battery last, ac power is not available. Load in and out is not an issue so full stack with deep cycle battery is ok. Generator is possible but not preferred. Anyone with practical experience? Thanks

After seeing all the replies, I think you should post what is your spending limit, how long is the gig/s, how many times will you be doing this. I can see some of the options are getting expensive, but more info is needed to give you the best option.

 

[Richard Martin]

On line specs for Honda

Using Honda and HF in the same sentence is against the rules of humanity. Honda makes the best inverter generators in the world. We have an EB2800, which isn't the quietest model they sell, but at no point during the show did anybody even know it was on. I bought it to use at home for my sensitive electronics and then I use my old Coleman 7500 watt generator to power the big loads.

 

[Al Kraft]

My older model Honda EU2000i has been rock solid and that story is the same for my friends who have them as well. I would imagine that the newer 2200 model would work even better for small outdoor events. The thing I like is that it will reliably and safely power a simple PA set-up (like for a big picnic, not a sports arena) and a bass amp all day on a single fill of gasoline.