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tripdoh
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Do 2Channel amps split the ohm load?
As far as I know when you bridge a 2channel amp and you have subwoofers wired up to lets say 2ohms the amp reads it as 2ohms right? I just recently had one of my "Older" installers tell me that if you bridge a 2channel amp it will split the ohm load. For example if you bridge some subs to 2channel amp and the ohm load is is 4ohm the amp will split that and will see 2ohms. Is that right? We agued that one for awhile. Your feedback will be really helpful.
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12012004 09:45 PM 
  

clawlan
Member

Ohms is resistance. More ohms = more resistance. Resistance is determined by the woofers. And depending on the resistance that is created by the woofer determines how many watts are able to "flow" from the amp. When you bridge an amp, all you are donig is combining the total watts from the channels. So if you have a 2 channel amp, half the watts will go to one channel and half to the other. When you bridge the amp, now all the watts go to one channel. This is nothing to do with ohms (resistance). So lets say you have an amp that puts out 500Wx2 at 4ohms and 1000Wx1 at 4 ohms. If you bridge the amp, you will be getting the 1000Wx1 SO LONG AS YOUR WOOFER IS WIRED TO 4OHMS. Hope this helps! Let me know if you need further explanation.
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12022004 01:44 AM 
  

korndog
Member

RE:
quote:
Originally posted on 12022004 by clawlan Ohms is resistance. More ohms = more resistance. Resistance is determined by the woofers. And depending on the resistance that is created by the woofer determines how many watts are able to "flow" from the amp. When you bridge an amp, all you are donig is combining the total watts from the channels. So if you have a 2 channel amp, half the watts will go to one channel and half to the other. When you bridge the amp, now all the watts go to one channel. This is nothing to do with ohms (resistance). So lets say you have an amp that puts out 500Wx2 at 4ohms and 1000Wx1 at 4 ohms. If you bridge the amp, you will be getting the 1000Wx1 SO LONG AS YOUR WOOFER IS WIRED TO 4OHMS. Hope this helps! Let me know if you need further explanation.
yea, its like batteries, stack them up + to  and voltage adds up. so when you bridge an amp you invert the single into one channel, but each is giving out the same amount of power, so you double the voltage. 4 ohms will never become 2ohms.
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12022004 03:54 AM 
  

lessismorespl
Member

RE: RE:
quote:
Originally posted on 12022004 by korndog yea, its like batteries, stack them up + to  and voltage adds up. so when you bridge an amp you invert the single into one channel, but each is giving out the same amount of power, so you double the voltage. 4 ohms will never become 2ohms.
Resistance is the opposition to the flow of current, Actually it would be more precise to say that resistance is the opposition to the flow of direct current. Impedance is the opposition to the flow of alternating current. AC causes some devices to act differently than they do with DC.
Now lets get more technical about this question.
People sometimes get confused as to why a 4 ohm mono and a 2 ohm stereo load are the same, as far as the amplifier is concerned. When two 4 ohm speakers are connected to each channel of a 2 channel amplifier, the amplifier is capable of driving the speakers with half of the total power supply voltage. If the amplifier has a power supply which produces plus or minus 20 volts, it will not be able to drive the speakers on a single channel with any more than 20 volts at any point in time. If we have a 2 ohm load on each channel, at the highest point on the waveform the amplifier will apply 20 volts to the speaker load. If we go back to ohms law...
I=V/R
I=20/2
I=10 amperes
If we take a single 4 ohm speaker and bridge it on that same amplifier, the amplifier will be able to apply twice the voltage across the speaker. This is because while one speaker terminal is being driven positive (towards the positive rail), the other terminal is being driven towards the negative rail. This will allow the entire power supply voltage to be applied to the speaker's voice coil. It will now be able to drive the 4 ohm speaker with 40 volts instead of 20 volts in the previous example. Back to Ohm's law...
I=V/R
I=40/4
I=10 amperes
The same amount of current flows through the output transistors whether the amplifier is driving a 4 ohm mono load or 2 ohm stereo load. As far as the amplifier is concerned, they are the same load.
Some people say that when an amplifier is bridged onto a 4 ohm load, it 'sees' a 2 ohm load. While it is true that the same current flows whether the amp is bridged on a 4 ohm load or a 2 ohm stereo load, the amplifier is driving a 4 ohm load across its outputs. A single 4 ohm speaker can never be a 2 ohm load.
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12052004 12:20 PM 
  

smgreen20
Member

You're both right. The over all ohm load is what you're refering to, is what the amp sees as a whole. Your friend, I would assume, is talking about each channel. Lets say your amp is:
4 ohms
75 X 4, or
300 X 1
2 ohms
150 X 2
If you take a 4 ohm bridged load at 300 watts, each channel will see half of the ohm load, or 2 ohms. Now the amp does 150 X 2 at 2 ohms. I hope I don't need to go into further detail, you can see the math is adding up. Your friend is saying that each channel see half of the total bridged ohm load.
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12082004 09:33 PM 
  
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