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DC to AC Inverter,How Many Watts ?

Discussion in 'Amp Tech Center' started by Jammin'John, Mar 11, 2017.

  1. Jammin'John

    Jammin'John Friend of Leo's

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    Hi Guys. I want to be able to run a guitar amp off my motorcycle and car 12 volt systems.
    An amp like a 2 x 6v6 Tweed Deluxe.
    Can I use a power inverter and if so how many watts ?
    http://www.harborfreight.com/automotive-motorcycle/power-inverters.html?order=Sort+Price,t
    http://www.homedepot.com/b/Outdoors...er-Inverters/N-5yc1vZbxdu?Ns=P_REP_PRC_MODE|0
    http://dcacpowerinverters.com/12_volt_power_inverters.html
    http://www.ebay.com/sch/i.html?_sop=15&LH_BIN=1&_nkw=dc+to+ac+power+inverter&_pgn=9&_skc=1600&rt=nc
    If a tube amp is impossible maybe a 20 or 30 watt solid state,a class D,or a nutube class D ?
    http://voxamps.com/MV50

    thanks,
    JJ
     
  2. dsutton24

    dsutton24 Doctor of Teleocity Ad Free Member

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    Watts are easy. The back panel may tell you how many watts input power the amp draws. If not, and it tells you how much current, multiply the current times 120 to get watts. If that's not there, multiply the size of the fuse by 120 to get watts.

    Some inverters are electrically noisy things. Buy it from someplace that will allow you to return it if it's unusable.
     
  3. Sandhill69

    Sandhill69 Tele-Holic

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  4. BobbyZ

    BobbyZ Doctor of Teleocity

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    Based on my limited experience with inverters, you want one rated about three times higher than you think you need. They seem to be rated on the optimistic side. And they kill batteries really fast. If it plugs into a cigarette lighter it's too small.
    I tried to run a Vibro Champ on one once but just ended buying a cheap solid state amp.
     
  5. maj34

    maj34 Tele-Meister

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    As sandhill suggested, a sine inverter would be a MINIMUM requirement (in my opinion). All other inverters are putting out square waves or modified square wave signals. The cheaper inverters will risk every component in your amp - especially your input transformer. And I'm fairly certain you'll hear a lot of noise through the amp, especially a tube amp.

    So yeah, a pure sine inverter, and a good one at that. I'd exceed the wattage significantly - because many devices get noisy again when pushed to their limits. For a 30 watt amp (and don't go by waht the amp is called, check the electrical info on the cord or bottom of the amp somewhere) I'd suggest a 100 watt or a 200 watt inverter. The 100 watt would probably do, but you may find more uses for a 200watt (other than your guitar).

    The other bad news is that you're going to run down your cars battery. Faster on a motorcycle battery.

    I'd think a Yamaha THR-10 with fresh batteries would be a better bet. Or microcube, vox da5, whatever your small battery powered amp preference is.
     
  6. maj34

    maj34 Tele-Meister

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    Pignose Legendary 7-100 amp would be an interesting way to go too.
     
  7. Jammin'John

    Jammin'John Friend of Leo's

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    Inefficient and noisy are not very desirable options. Maybe not so with a pure sine wave inverter ?
    There aren't ANY battery powered tube amps available and the choice of solid state amps that are battery powered is very limited.
    My Brown Deluxe says 117 volts,1.1 amps and has a 2 amp fuse. 2 x 120 = 240 watts.
    http://www.ebay.com/sch/i.html?_odk...RS0&_nkw=pure+sine+wave+inverter+12v&_sacat=0

    What about a power amp made for a car with some kind of preamp to have a guitar input ?

    JJ
     
  8. Jammin'John

    Jammin'John Friend of Leo's

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    "I'd think a Yamaha THR-10 with fresh batteries"

    It takes EIGHT double AA's.

    JJ
     
  9. Obsessed

    Obsessed Telefied Silver Supporter

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    Actually part of the issue is the efficiency of the inverter itself. The inverter uses power while being used, so the more efficient inverters are pretty expensive. I've been living off of an inverter for close to 20 years now and if you really need to run a 2x6v6 amp for more than about 15 minutes, you are going to have to change your idea. Either a Honda like portable generator, multiple batteries in parallel, a less powerful tube amp, a SS amp or a powered battery amp. Take your pick.
     
  10. Obsessed

    Obsessed Telefied Silver Supporter

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    Or you could put a huge number of solar panels on a trailer behind you and only play during daylight hours.
     
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  11. Obsessed

    Obsessed Telefied Silver Supporter

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    Or you could use a wind turbine and only play at 60 mph.:D
     
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  12. maj34

    maj34 Tele-Meister

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    Yeah, and lots of people on tdpri play $2000 guitars and have Costco memberships. Get some rechargeables if need be. I get 8 good hours playing time out of a set, and plug in when I can.

    The original poster is looking at a inverter solution for a motorcycle. Going on AA batteries is not out to lunch.

    It takes volts and mAh to power an amp.
     
  13. aerhed

    aerhed Friend of Leo's

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    You'd have to leave yor car running or you probably won't get home. That said, I've fought this battle and for loads you describe either an Exeltech 1000 watt or a Samlex 600 watt true sine will run a couple tube amps dead quiet if you have a good chassis ground from inverter back to battery negative. I have both 300 and 600 Samlex. The 300 is usable, but the 600 is way cleaner.
     
  14. RLee77

    RLee77 Friend of Leo's

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    Some good advice here. I would add that equipment panel ratings are usually not very accurate. I would measure current drawn with an ammeter. Manufacturers are usually conservative on panel ratings, so the numbers are usually higher than actual measurements. Fuse ratings are not an accurate estimate.
    Then convert the measurement to total watts, then scale that using the battery voltage to get battery amps, and adjust for efficiency. This will give you estimated battery drain regardless of what rating inverter you decide.
    Example… say your amp measures 0.75 amp at 120vac: 90 watts. Divide by 12vdc to get battery amps: 7.5amps
    With a 90% efficient inverter, 7.5/.90 is 8.3 amps. So your battery drain will be around 8 or 9 amps, which, as others have already advised, is pretty significant. Even for a car battery. You'd have to start the car to keep the battery charged, how often I don't know.
     
    Last edited: Mar 12, 2017
  15. Jammin'John

    Jammin'John Friend of Leo's

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    Holy guacamole. I had no idea it would be such a project. It looks like I could only run a small SS amp with my bike.
    What about a power amp made for a car stereo with some kind of SS preamp to have a guitar input ?
    How about a dedicated motorcycle battery charged up at home in a saddlebag ?
    The better portable SS amps are $3 - 400 bucks.
    JJ
     
  16. maj34

    maj34 Tele-Meister

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    If you're trying to play anytime, anywhere your car or motorcycle can drive, you're going to have a rough time making this work in my opinion. Especially since you were looking for some quality sound (quoting a 2x6v6 Princeton style amp) and are reluctant to get into a 3-400$ solid state amp.

    You're on to something with a SS preamp and using your cars sound system. But you're still running your car battery down with the sound system. Even if you master the art of not killing your battery, it's hard on your battery and to some degree on your starting motor.

    But you need to ask yourself what kinda sound quality do you want here. There's a huge difference in a Princeton Reverb and a Vox Amplug sound quality.

    Motorcycle (and car) batteries are not intended to be charged up and run down. Thin plate batteries like this are meant to be charged and kept charged, used to pull a lot of current (i.e. start your car) and then get charged again. You'll ruin a car/motorcycle battery really quickly by using it for your guitar amp.

    A wheelchair battery would be the better technology (deep cycle). You can probably get a 50AH for $100 (guess). You're not supposed to run these down 100% either. So out of that 50AH you get 20 usable AH each charge cycle. That's 20 amps for a hour or 1 amp for 20 hours.

    Your princeton-style amp we call a 12W amp. Who knows what it really draws. Lets say 10 watts and it requires 110V. Adding in some inverter inefficiency, you're probably going to draw about 1A to run that amp. So you get 20 hours runtime out of your battery. Not bad. But here's your cost estimate:

    - Heavy Battery $100
    - Good true sine inverter $150-200
    - Decent deep cycle charger $100

    Difficult for me to come up with costs in USD though, because I'm in Canada. In Canada that'd be a $5-600 project.
     
  17. Jammin'John

    Jammin'John Friend of Leo's

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  18. maj34

    maj34 Tele-Meister

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  19. Jammin'John

    Jammin'John Friend of Leo's

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    Yea,I remember. Does it have a 12 volt input like an effects pedal ?

    JJ
     
  20. maj34

    maj34 Tele-Meister

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    It has a 15V that is meant to be fed from the supplied power adapter. You'd still need an inverter... or AAs. A lot of people have been happy with Eneloop batteries on this model. You can get 16 Eneloops for $36 on Amazon. You'll need a charger too. Then keep 8 in the Yamaha and another 8 on standby.
     
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