Ohms and channels and RMS... Oh my...
05-15-2005, 10:44 AM
#21
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Originally Posted by bottlefed90GT
Only if you are working with speakers of the same ohm/resistance. Once you start parralleling a 4-ohm and 8-ohm speaker, your system would be 6-ohm, right? The true resistance would be 2.66667. (4x8 / 4+8)
Exactly...you beat me to it
05-15-2005, 08:08 PM
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Originally Posted by 02Z28LS1
inefficient? yes.....stupid? not necessarily.
the lower the impedance load on the amp, the higher the temperatures will be, due to the extra current that it is having to push. in a hotter climate (such as here in Texas during the summer), this could cause the amp to die before its time. it's generally not a concern if the amp has plenty of air around it to dissipate that heat, and a large enough heatsink to get that heat to the outside air, but it is still a factor to consider.
also, the more current that is drawn by the amp(s), the larger the requirement for the gauge of power wire....not to mention the more current that is drawn from the vehicle's power source, which in some cases, can cause further problems (such as headlight dimming, and faster drain on the battery when the car is not running).
so i would not really call someone stupid for running the amp at only 4 ohms....
the lower the impedance load on the amp, the higher the temperatures will be, due to the extra current that it is having to push. in a hotter climate (such as here in Texas during the summer), this could cause the amp to die before its time. it's generally not a concern if the amp has plenty of air around it to dissipate that heat, and a large enough heatsink to get that heat to the outside air, but it is still a factor to consider.
also, the more current that is drawn by the amp(s), the larger the requirement for the gauge of power wire....not to mention the more current that is drawn from the vehicle's power source, which in some cases, can cause further problems (such as headlight dimming, and faster drain on the battery when the car is not running).
so i would not really call someone stupid for running the amp at only 4 ohms....
If someone bought two single voice coil 4-ohm speakers, and bought a 75 watts rms x 2 amp, they would be pushing 75 watts rms to each speaker. That's fine, you won't overheat the amp. BUT, you did pay the money for an amp that should be able to do 150 watts rms x 2 at 2 ohms, or 300 watts rms x 1 at 2 ohms, which is commonly considered something around a 600 watt amp (total power). You would only use half the available wattage.
If all you want is 75 watts rms to each speaker, then it would make more sense to get two 8-ohm single voice coil speakers, parallel them to make 4-ohms, bridge an amp that is rated at 37.5 watts rms x 2, and you will pull 150 watts rms x 1 at 2-ohms. This way, you are paying for a 300 watt amp, and still getting your 75 watts rms per channel. This would still be fine with the same gauge wire as if you were to run a 600 watt amp at 4-ohms and pull half the power from it.
Point is, know what you are buying. I have had too many friends come home from Circuit City or Brandsmart complaining about how their new system sounds. I yank the speakers out, and see that they sold them two 4-ohm speakers, and are running the amp at 4-ohms stereo. They say, "but it's a 600 watt amp?" Then I go on to explain how they should have asked someone more knowledgeable, or read up first.
05-16-2005, 01:22 PM
#23
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Hey, sorry I've been out of contact.
The subs I have are Dual 4-Ohm Voice Coil. They are rated at 1000 Watts each (I'm sure this is peak ratings, right?)
The amp I have (waiting to be repaired if it will work) is the Punch Power series 250.1
The amp pushed 2 Cerwin Vega 12's past the breaking point rather effortlessly, so I think it will make enough power to push these subs enough to make some serious noise, but I think it may be configured wrong for the DVC 4-ohm setup, leading to a shortened life span.
It is a single channel (is that the same as "Mono", a single set of "Outs" to the speakers?) amp, but it has 2 pair of "In's" from the power source... what would that be like that for?
Thanks again for all the incredible advice and information, I am really trying to get the Ohm's Law to make sense in my head, I am working on it.
Thanks again!
Taco
The subs I have are Dual 4-Ohm Voice Coil. They are rated at 1000 Watts each (I'm sure this is peak ratings, right?)
The amp I have (waiting to be repaired if it will work) is the Punch Power series 250.1
The amp pushed 2 Cerwin Vega 12's past the breaking point rather effortlessly, so I think it will make enough power to push these subs enough to make some serious noise, but I think it may be configured wrong for the DVC 4-ohm setup, leading to a shortened life span.
It is a single channel (is that the same as "Mono", a single set of "Outs" to the speakers?) amp, but it has 2 pair of "In's" from the power source... what would that be like that for?
Thanks again for all the incredible advice and information, I am really trying to get the Ohm's Law to make sense in my head, I am working on it.
Thanks again!
Taco
05-16-2005, 01:39 PM
#24
hey i used to run those same subs in my camaro, buy a 1000 watt cross fire amp, run it at 1 ohm, run the subs series parrellel and you will love every minute of gut wrenching bass that comes out of them
05-17-2005, 10:33 AM
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I can't find any true specs on that Punch 250.1 amp. Can you post up as much info on that amp as you have? We at least need to know how many watts @ what ohms? Also need to know the stability of the amp (4-ohm stable, 2-ohm stable, or 1-ohm stable). Any other info may help too, so give us all you got.
