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Thread: Does amp draw more power 1 ohm vs 2? |
    
Silver Member Username: Tafkam
Texas
Post Number: 124
Registered: Apr-04
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| Posted on Tuesday, December 14, 2004 - 09:56 am: |
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If I run my amp at one ohm (yes it is rated one ohm stable) will it draw more power from the electical system of my truck then if I run it at two ohms? Or is it just drawing X amount of power to run, period? |
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Silver Member Username: Carguy
Post Number: 857
Registered: Nov-04
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| Posted on Tuesday, December 14, 2004 - 10:51 am: |
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Hey Tafkam, using an amp at 1ohm will draw more current cause it's putting out more power than at 2ohms.
However if you lower your volume control equivalent to 2ohm's power output, then they'll use same amount of current.
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Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 6426
Registered: Dec-03
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| Posted on Tuesday, December 14, 2004 - 11:22 am: |
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if the amplifier isn't regulated to put out the same wattage at both 1 and 2 ohms (like the JBL BP series) then yes. power watts = more current draw.
remember watts = volts * amps (plus a bit more added for inefficiency and loss to heat)
so if the amp doubles it's wattage at 1 ohm compared to 2 ohms, then you'll draw twice the current as well.
if this is a class D amp, for example, and it puts out say 750 watts @ 2 ohms, you'll need 75A of current. At 1 ohm the amp puts out 1500 watts, and needs 150A of current (figuring in a 20% loss to heat)
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Silver Member Username: Carguy
Post Number: 865
Registered: Nov-04
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| Posted on Tuesday, December 14, 2004 - 11:54 am: |
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I wish I had an amp that had 75% loss to heat. It's freezing this morning. |
Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 6440
Registered: Dec-03
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| Posted on Tuesday, December 14, 2004 - 12:36 pm: |
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haha
my three 2250SX amps lose about 40% to heat..
at 1280 watts each from two, and 500+ watts from the third, it actually does warm up the car a bit at times...
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Silver Member Username: Tafkam
Texas
Post Number: 125
Registered: Apr-04
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| Posted on Tuesday, December 14, 2004 - 04:16 pm: |
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Thanks guys, just trying to figure out if I want to go with a new sub that will draw 2 or 1 ohm from that amp. Getting an Orion H2 10 inch, and have a Hifonics Brutus 1500D which will do 1000 watts at 2 ohms or 1500 at one. Sounds like the 2 ohm load is the best choice, save some drain on my alternator....... |
Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 6464
Registered: Dec-03
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| Posted on Tuesday, December 14, 2004 - 06:02 pm: |
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at 2 ohms, the drawback is less power and thus less SPL.
the pros however are as follows (compared to a 1 ohm load
less THD
better SNR
better damping
more dynamic head room from the amplifier and it's power supply
less current draw from your charging system (about 100A instead of 150A at full output)
less heat generated, and thus longer life (theoretically at least)
more efficient at 2 ohms than at one, since the lower the load, the more power you lose to heat and efficiency (half the load only yielding a 50% gain in power for example, instead of doubling the power.)
better overall SQ (at least on a scope, and on paper. audibly, may never notice.)
less current not only means less draw, but the ability to possibly use smaller wire gauge for the system run as a result, which means less money and less routing work.
as you're probably beginning to notice, the advatanges are numerous for running at higher loads (4 ohms being pretty much ideal for car audio amplifiers.) whereas the only real gain from running ultra-low loads is the increase in power per dollar spent.
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Silver Member Username: Tafkam
Texas
Post Number: 127
Registered: Apr-04
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| Posted on Tuesday, December 14, 2004 - 11:53 pm: |
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Thanks again Glass I think running it at two ohms is a good compromise for me. Thanks for pointing all of those things out. |
Silver Member Username: Tafkam
Texas
Post Number: 128
Registered: Apr-04
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| Posted on Tuesday, December 14, 2004 - 11:57 pm: |
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ps Glass Bacon already let me know on this but wanted to get your take if you are still following the thread, do you think the Orion H2 10 inch is a good choice to run with my amp at two ohms? I think the sub is rated at 2000 rms but I would only be giving it 1000 rms. matter or not? |
Gold Member Username: Glasswolf
NorthWest,
Michigan
USA
Post Number: 6504
Registered: Dec-03
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| Posted on Wednesday, December 15, 2004 - 04:47 pm: |
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good subs.
1Kw should still yield good results.
the thermal rating for the sub doesn't mean it needs that much to reach full output, so 1Kw in the right box may be all you need for peak xmax.
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Silver Member Username: Tafkam
Texas
Post Number: 129
Registered: Apr-04
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| Posted on Wednesday, December 15, 2004 - 11:26 pm: |
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thanks again |
