Wiring / Ohm help...
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Wiring / Ohm help...
Ok, My friend has wired up his car in this way.
How long will this last? What are the speakers impedance? What kinda power are they getting?
The front channels are both 4 ohm speakers and are a component set. The rear channel is what I don't understand.
The rear 6x9's are 4 ohms and the 10" sub is 4 ohm. He has the 6x9's running off the amp channels like they are supposed to be, but the sub is running off the rear channel as if it were bridged (R + and L -). He said that a car audio shop told him he could run it this way until he gets another amp. I have my doubts about this set-up.
Can anyone prove him right or me right?
Can anyone clear this up and provide some concrete proof as to what loads are being placed on the amp and speakers?
How long will this last? What are the speakers impedance? What kinda power are they getting?
The front channels are both 4 ohm speakers and are a component set. The rear channel is what I don't understand.
The rear 6x9's are 4 ohms and the 10" sub is 4 ohm. He has the 6x9's running off the amp channels like they are supposed to be, but the sub is running off the rear channel as if it were bridged (R + and L -). He said that a car audio shop told him he could run it this way until he gets another amp. I have my doubts about this set-up.
Can anyone prove him right or me right?
Can anyone clear this up and provide some concrete proof as to what loads are being placed on the amp and speakers?
1) no one can tell you how long it will last. it could go forever but most likely about 5 minutes if that.
2)is it 100 rms or 100 max?
3)its just wrong tell him to run the fronts how he has them run the by9s off the deck and amp the sub. otherwise the sub will need to be playing voices for the by9s to sound good. this is crap.
2)is it 100 rms or 100 max?
3)its just wrong tell him to run the fronts how he has them run the by9s off the deck and amp the sub. otherwise the sub will need to be playing voices for the by9s to sound good. this is crap.
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Tell him to run both fronts and 6x9s off the front channel (two left speaks on left, two right speakers on right, half the impedance, as long as the amp can do it you'll get more power to your highs, I have been running it like that on my amp for years and it sounds great) and run the sub off the rear two channels bridged, tell him to look in the manual on how to bridge the two channels, there is almost certainly a way to do it. so he'll be running his 4 channel amp in 3 channel mode. Make sure you can switch the rear channels to lowpass, you don't want to pump fullrange into a sub or it'll sound like ****. if the amp has no built in crossover, you can get one pretty cheap.
Also, tell him to go to another sound shop, the guys at that shop are obviously idiots.
Also, tell him to go to another sound shop, the guys at that shop are obviously idiots.
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ya know hwat, either amp the 6x9's or amp the sub off the rear channels, don't use both. don't run both sets of speakers off the front channels, don't run the sub and rear speakers on the rear channels. just don't. if he is going to buy a sub amp anyway, he can make do for the time being. there is no ideal way to hook up all that stuff to that amp, so don't try. for now, just deal with it.
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Rep Power: 0 what is wrong with what I described? I have an Alpine 5 channel amp I am running my fronts and 6x9s off the front channels on high pass, 2 MBQuart 8" subs on low pass on the rear two channels (monoed to one channel, both speakers together in the same fashion) and an MTX 12" on the sub channel. It sounds fantastic and is loud and crystal clear. It's been hooked up that way for about 4 years now and still going strong (see my pictures on my stuff on the new pictures thread)
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Rep Power: 0 I talked to my idiot friend this morning. He said that he got the idea off the internet.
I knew he didn't hear that from any reasonable sound shop. I was gonna be nice and give him an old kicker 2 channel amp I had lying around, but now I'm not so sure he won't do something retarded with it!
I knew he didn't hear that from any reasonable sound shop. I was gonna be nice and give him an old kicker 2 channel amp I had lying around, but now I'm not so sure he won't do something retarded with it!
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Rep Power: 0 Wow, where to begin!!!!!!
After 4 hours of reading, I found that this set-up can be used!!!!!!!
It's called Tri-mode power distribution.
This was copyed and pasted from Basic Car Audio Electronics.com
Click here to view original Document with pics!!!
Tri-Mode Power Dissipation
On this page I will try to help you understand how the power is distributed in a tri-mode configuration.
For this example, we will assume:
The amplifier is stable into 2 ohms stereo and 4 ohms mono
The amplifier will produce 100 watts per channel into 4 ohm stereo, 200 watts per channel into 2 ohms or 400 watts into 4 ohm mono. Read the Amplifier Bridging page if you don't understand why the output power is 4 times as high when bridged as it is for each channel in 4 ohm stereo.
When it is said that the load on the amplifier is increased, it means that the impedance of the speaker load is decreased and there fore putting more stress on the amplifier.
This image is a review of the signals present on each of the speaker output terminals of a bridgeable amplifier. All of the lines of the same color are connected together. You can see that the left positive output has the 'normal' signal and the right negative has the 'inverted' signal. The left negative and the right positive are connected to a reference (ground) and have no signal on them.
In this diagram, you can see that the voltage across the subwoofer is twice the voltage of the stereo speakers. The little 'probes' show the points where the voltage would be measured/read and the gray display shows the voltage measured by the probes above each display.
If we use the Ohm's Law formula: P=E^2/R
If the small speakers are 4 ohms each and the sub is an 8 ohm speaker...
We can see that the smaller speakers will dissipate:
P=20^2/4
P=400/4
P=100 watts per channel.
The 8 ohm sub will dissipate:
P=40^2/8
P=1600/8
P=200 watts into the bridged speaker.
The total power dissipation is 100 watts for each of the 4 ohm stereo speakers plus 200 watts into the bridged 8 ohm speaker. The total power output/dissipation is 400 watts. The same total power as if you were running the amplifier into a 4 ohm bridged OR a 2 ohm stereo load.
--------------------------------------------------------------------------------
Tri-mode with different types of speakers:
In the previous diagrams, it was assumed that all of the drivers were woofers. All of the speakers were directly connected to the amplifier (no crossover components). If you use passive crossovers (capacitors or coils), the system will be able to drive more speakers without increasing the effective load on the amplifier. If the 'stereo' speakers in the previous diagram are 4 ohms each and the bridged speaker is an 8 ohm speaker, the amplifier will be loaded to its maximum safe load (the amp is 2 ohm stereo or 4 ohm mono stable). Using passive crossovers, the 'stereo' speakers could be 2 ohms and the bridged speaker could be a 4 ohm speaker and the load would still be a safe load. Without the crossover components, the amp would 'see' a 1 ohm stereo/2 ohm mono total load.
For this next example... If the passive crossover has a crossover point of 150 hertz and the crossover components are connected as follows:
The high frequency speakers will not load the amplifier below 150 hertz and the low frequency speakers will not load the amplifier above 150 hertz. In the real world, the point where the high and low pass speakers stop being a load on the amplifier is not as abrupt as this and there is actually an overlap of frequencies where both high and low frequency drivers are a load (albeit an ever decreasing load) on the amplifier. There is no single point in the audio spectrum where both the high frequency and low frequency drivers present their rated impedance to the amplifier.
On the following graph, the violet line is the effective impedance of the high frequency speakers. You can see how the impedance keeps rising.
At point 'A', the effective impedance of the speakers is equal to the rated impedance of the speakers. When the line transitions from the flat area to the knee of the slope, the impedance presented to the amplifier starts to increase (the amplifier 'sees' a lighter load).
At point 'B', the effective impedance of the driver and series crossover component is 1.4 times the impedance of the driver. This is the 3dB down point of the 150hz crossover.
At point 'C', the effective impedance is twice the impedance of the driver.
At point 'D', the effective impedance is 2.8 times the impedance of the driver.
This is the impedance plot of the low frequency drivers. The description from the previous graph also applies here.
--------------------------------------------------------------------------------
Losing Headroom in Trimode Operation
Loss of Headroom:
When using an amplifier without an electronic crossover, you lose some head room. In the following 2 diagrams, you can see two sine waves that have plenty of headroom. This is a 100hz sine wave.
And here you can see a 2000hz sine wave.
You can see (in the previous pictures) that neither of the sine waves are near the top or bottom of the window (black area). In the next picture you can see that the higher frequency is 'riding' on top of the lower frequency. When both of the frequencies are mixed together (below), you can see that they are very close to reaching the top and bottom of the window (we will consider the upper and lower borders of the window to be 'clipping'). You should also notice that the individual signals are exactly the same levels that they were before they were mixed. If the volume were only slightly increased (above the present volume setting), the amplifier would start to clip. When using an electronic crossover, the signal in third picture is separated back into the signals in the first and second pictures (if the crossover point was set approximately in the center of 100 and 2000hz).
More info on clipping:
Read the "Too Little Power" page.
Don't Panic!:
This does not mean that a tri-mode configuration can't sound good. It just means that you'll have less power available to the highs and lows when the audio has both high and low frequency content. If the audio is a pure low frequency sine wave, you'll have approximately the same headroom as with an electronic crossover. If there are multiple frequencies (as you have with normal music), the higher frequencies will be 'riding' on top of the lower frequency waves and your dynamic headroom will be reduced.
After 4 hours of reading, I found that this set-up can be used!!!!!!!
It's called Tri-mode power distribution.
This was copyed and pasted from Basic Car Audio Electronics.com
Click here to view original Document with pics!!!
Tri-Mode Power Dissipation
On this page I will try to help you understand how the power is distributed in a tri-mode configuration.
For this example, we will assume:
The amplifier is stable into 2 ohms stereo and 4 ohms mono
The amplifier will produce 100 watts per channel into 4 ohm stereo, 200 watts per channel into 2 ohms or 400 watts into 4 ohm mono. Read the Amplifier Bridging page if you don't understand why the output power is 4 times as high when bridged as it is for each channel in 4 ohm stereo.
When it is said that the load on the amplifier is increased, it means that the impedance of the speaker load is decreased and there fore putting more stress on the amplifier.
This image is a review of the signals present on each of the speaker output terminals of a bridgeable amplifier. All of the lines of the same color are connected together. You can see that the left positive output has the 'normal' signal and the right negative has the 'inverted' signal. The left negative and the right positive are connected to a reference (ground) and have no signal on them.
In this diagram, you can see that the voltage across the subwoofer is twice the voltage of the stereo speakers. The little 'probes' show the points where the voltage would be measured/read and the gray display shows the voltage measured by the probes above each display.
If we use the Ohm's Law formula: P=E^2/R
If the small speakers are 4 ohms each and the sub is an 8 ohm speaker...
We can see that the smaller speakers will dissipate:
P=20^2/4
P=400/4
P=100 watts per channel.
The 8 ohm sub will dissipate:
P=40^2/8
P=1600/8
P=200 watts into the bridged speaker.
The total power dissipation is 100 watts for each of the 4 ohm stereo speakers plus 200 watts into the bridged 8 ohm speaker. The total power output/dissipation is 400 watts. The same total power as if you were running the amplifier into a 4 ohm bridged OR a 2 ohm stereo load.
--------------------------------------------------------------------------------
Tri-mode with different types of speakers:
In the previous diagrams, it was assumed that all of the drivers were woofers. All of the speakers were directly connected to the amplifier (no crossover components). If you use passive crossovers (capacitors or coils), the system will be able to drive more speakers without increasing the effective load on the amplifier. If the 'stereo' speakers in the previous diagram are 4 ohms each and the bridged speaker is an 8 ohm speaker, the amplifier will be loaded to its maximum safe load (the amp is 2 ohm stereo or 4 ohm mono stable). Using passive crossovers, the 'stereo' speakers could be 2 ohms and the bridged speaker could be a 4 ohm speaker and the load would still be a safe load. Without the crossover components, the amp would 'see' a 1 ohm stereo/2 ohm mono total load.
For this next example... If the passive crossover has a crossover point of 150 hertz and the crossover components are connected as follows:
The high frequency speakers will not load the amplifier below 150 hertz and the low frequency speakers will not load the amplifier above 150 hertz. In the real world, the point where the high and low pass speakers stop being a load on the amplifier is not as abrupt as this and there is actually an overlap of frequencies where both high and low frequency drivers are a load (albeit an ever decreasing load) on the amplifier. There is no single point in the audio spectrum where both the high frequency and low frequency drivers present their rated impedance to the amplifier.
On the following graph, the violet line is the effective impedance of the high frequency speakers. You can see how the impedance keeps rising.
At point 'A', the effective impedance of the speakers is equal to the rated impedance of the speakers. When the line transitions from the flat area to the knee of the slope, the impedance presented to the amplifier starts to increase (the amplifier 'sees' a lighter load).
At point 'B', the effective impedance of the driver and series crossover component is 1.4 times the impedance of the driver. This is the 3dB down point of the 150hz crossover.
At point 'C', the effective impedance is twice the impedance of the driver.
At point 'D', the effective impedance is 2.8 times the impedance of the driver.
This is the impedance plot of the low frequency drivers. The description from the previous graph also applies here.
--------------------------------------------------------------------------------
Losing Headroom in Trimode Operation
Loss of Headroom:
When using an amplifier without an electronic crossover, you lose some head room. In the following 2 diagrams, you can see two sine waves that have plenty of headroom. This is a 100hz sine wave.
And here you can see a 2000hz sine wave.
You can see (in the previous pictures) that neither of the sine waves are near the top or bottom of the window (black area). In the next picture you can see that the higher frequency is 'riding' on top of the lower frequency. When both of the frequencies are mixed together (below), you can see that they are very close to reaching the top and bottom of the window (we will consider the upper and lower borders of the window to be 'clipping'). You should also notice that the individual signals are exactly the same levels that they were before they were mixed. If the volume were only slightly increased (above the present volume setting), the amplifier would start to clip. When using an electronic crossover, the signal in third picture is separated back into the signals in the first and second pictures (if the crossover point was set approximately in the center of 100 and 2000hz).
More info on clipping:
Read the "Too Little Power" page.
Don't Panic!:
This does not mean that a tri-mode configuration can't sound good. It just means that you'll have less power available to the highs and lows when the audio has both high and low frequency content. If the audio is a pure low frequency sine wave, you'll have approximately the same headroom as with an electronic crossover. If there are multiple frequencies (as you have with normal music), the higher frequencies will be 'riding' on top of the lower frequency waves and your dynamic headroom will be reduced.
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From: B.C., Canada
Rep Power: 786 yes it can be used, does that make it a good idea? no, certainly not. however the diagram provided is not the same as what is described in that article.
the article states that using 4 ohm speakers and an 8 ohm woofer can maintain a safe load on the amplifier... if the subwoofer is a dual 4 ohm speaker wired in series to 8 ohm, you can wire it up that way no problem. if not, you will be below the safe load on the amplifier. as quoted in the article, when using passive crossovers "There is no single point in the audio spectrum where both the high frequency and low frequency drivers present their rated impedance to the amplifier". when NOT using passive crossovers, the low frequency and high frequency drivers will present their rated impedence to the amplifier at EVERY point in the audio spectrum as opposed to no points when using passive crossovers. you make no mention of using passive crossovers in the diagram that you posted so I will conclude that you aren't using them and that your amplifier will run at an unsafe load.
should your woofer be dual 4 and you wire it to 8, yes you have satisfied the requirement of safely loading your amplifier. however, you now have to deal with the slightly less important problem of all your speakers playing full range. not so much of a problem for your 6x9's, but it will make your sub sound terrible. also, use a passive crossover on your sub and it will eat up the majority of your power and the sub will barely move. turning it up even more will only make the speakers distort, the amp will become unstable and poof goes your speakers. I could go on even further but won't becuase htat will open up a whole other can of worms, and I don't think a temp setup should ever have this much thought put into it. I personally don't have rear speakers in my car anyway, and I prefer it that way (only having front speakers) to help give the effect of live sound or the concert hall effect in the front of my car.
in conclusion, don't do it
the article states that using 4 ohm speakers and an 8 ohm woofer can maintain a safe load on the amplifier... if the subwoofer is a dual 4 ohm speaker wired in series to 8 ohm, you can wire it up that way no problem. if not, you will be below the safe load on the amplifier. as quoted in the article, when using passive crossovers "There is no single point in the audio spectrum where both the high frequency and low frequency drivers present their rated impedance to the amplifier". when NOT using passive crossovers, the low frequency and high frequency drivers will present their rated impedence to the amplifier at EVERY point in the audio spectrum as opposed to no points when using passive crossovers. you make no mention of using passive crossovers in the diagram that you posted so I will conclude that you aren't using them and that your amplifier will run at an unsafe load.
should your woofer be dual 4 and you wire it to 8, yes you have satisfied the requirement of safely loading your amplifier. however, you now have to deal with the slightly less important problem of all your speakers playing full range. not so much of a problem for your 6x9's, but it will make your sub sound terrible. also, use a passive crossover on your sub and it will eat up the majority of your power and the sub will barely move. turning it up even more will only make the speakers distort, the amp will become unstable and poof goes your speakers. I could go on even further but won't becuase htat will open up a whole other can of worms, and I don't think a temp setup should ever have this much thought put into it. I personally don't have rear speakers in my car anyway, and I prefer it that way (only having front speakers) to help give the effect of live sound or the concert hall effect in the front of my car.
in conclusion, don't do it
Last edited by MegaHurtz; Jul 6, 2005 at 04:43 PM.
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Rep Power: 0 Thats cool. I knew that the impedance was different and that it wouldn't be good, I just wanted to show that it is possible. (And answer my first post.)
Thanks for the break down Mega.
Thanks for the break down Mega.
Last edited by LayinLo; Jul 6, 2005 at 04:58 PM.
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