Stupid question...

 

Silver Member
Username: Newb

Post Number: 209
Registered: Dec-03
does a amp running 500w at 2 ohms put the same load on the alternator as an amp running 500w at 4 ohms?
 

Gold Member
Username: Blainew

Post Number: 1113
Registered: Nov-05
i was wondering that too
 

Bronze Member
Username: Bachatero07

Post Number: 92
Registered: Mar-06
yes because they are both demanding the same amount of power from the alt. now if say that same 4ohm amp was to be bridged, then it would be something like 8 or 900 watts. which would be a bigger demand on the alt. ohms only refers to the resistance of the speaker. there is no such thing as a stupid question. jus dumb and unthought out ones. lol. j/k.
 

Gold Member
Username: Blainew

Post Number: 1114
Registered: Nov-05
are you 100 % positive??

bc if you think about it it would seem that the 4 ohm way would demand more current bc there is more resitance..like it would need to work harder to get the same amount of watts...and at one ohm it doesnt need to work as hard. kind of confusing.....
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 842
Registered: Jun-05
It would seem like it, true, Blaine. However, electricity dosnt follow a lot of things that most people would think to be common sense.

It draws no more current pushing the same amount of wattage at 4 ohms, as it would at 1 ohm. If anything - it's better to do it at 4 ohms, as it'll run cooler.
 

Silver Member
Username: N2audio

Lawrence, Ks USA

Post Number: 767
Registered: Mar-04
the most important consideration which I don't think has been mentioned is the amp's class.
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 843
Registered: Jun-05
^^^^ Not really. a class AB amp at 4 ohms would require as much as a class AB amp at 1 ohm.

He wasnt asking about the efficiency of various amplifier types.. (at least, not clearly..)

However, Optidriven does bring up a point you might not have known to even ask about..

A Class D amp at 4 ohms putting out 500 watts, would require even less current, than a class AB amp at 1 ohm putting out 500.
 

Bronze Member
Username: Ton

Post Number: 41
Registered: Jul-05
it's a bit confusing, let say you have an mono amp that is 150 amperes, and at 4ohm it is 500 wrms at 2ohm it is 1000wrms and at 1ohm it is 1500wrms. thus at any ohm the amp will draw the same current? it's bit confusing....where's GlassWolf..lol?
 

Gold Member
Username: Theelfkeeper

Stockbridge, GA USA

Post Number: 1640
Registered: Feb-05
same wattage but different loads shouldn't affect the current draw. output is the same, thats all that matters i think. things will just heat up faster at a lower impedance.

Aruman - 1500>1000>500 therefore 1500 watts will draw more current then 1000 which will draw more then 500. so in that case, it does affect the current draw of the amp.
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 845
Registered: Jun-05
a good example of this is my phoenix gold xenon amps.. (have a pair of 600.1's, and a 1200.1 running in my firechicken)

The 1200.1 produces 1200 watts, at 1 ohm, 1200 watts at 4 ohms, just the same.. At either impedance, it will draw the same current, however, running it at 4 ohms, would actually run cooler, with less distortion (THD %'s are better at a higher ohm load, in almost all cases.)
 

Silver Member
Username: Newb

Post Number: 212
Registered: Dec-03
thx for the input guys, now im even more confused....just kidding. well i know that class d amps are supposedly more efficient than ab amps, im assuming that why theyre more expensive.

i also know that a lot of amps arent stable at 1 ohm and the ones that are cost more. but as for seths example, thats only true for xenon gold amps isnt it. i know for some amps the specs will say 500w at 4 ohms, 900w at 2 ohms. or maybe im just confused? and if you bridge a multi channel amp its usually only stable to 4 ohms no?
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 11479
Registered: Dec-03
yes 500 watts is 500 watts.
This is basic Ohm's Law stuff.
watts = volts * amps.
voltage is always a constant. say, 12 volts.
if the wattage is a constant, and the voltage is a constant, that pretty much fixes the current as well.

regardless of load, 500 watts will draw the same amount of current as long as both amplifiers are the same design and class.
 

Silver Member
Username: Fandim

Reno, Nevada United State...

Post Number: 854
Registered: Jun-05
Chas D, not many amps are like the PG Xenon / JL slash series, true. Was just using it as an example.

Also - Class D amps are actually normally cheaper than their class AB counterparts, but are really only suitable for playing subwoofers.
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