dual voice coil 4ohm sub = 4ohm out? - Page 2 - Ranger-Forums - The Ultimate Ford Ranger Resource


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  #26  
Old 02-24-2009
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Originally Posted by rizoss16 View Post
There is supposed to be 1.5 cubic ft of air space, does that look like enough space? I am back at school for the week and once again don't have a tape measurer.
It's hard to eyeball measurements on the internet, lol. But if it's sealed, close enough.

If its too boomy, add pillow stuffing.
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  #27  
Old 02-24-2009
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It's a Power Acoustik amp and those specs are a ****ing joke and probably no where near real world outputs. With out the ability to raise the voltage more than double when bridged, the amp CAN NOT make more power bridged at 4ohm than it can 2ohm stereo. Essentially when you bridge two channels the amp knows no difference between 4ohm bridged and 2ohm stereo.
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The last time I checked 280W X 2 = 560W!!!



Last edited by Takeda; 02-24-2009 at 10:11 AM.
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  #28  
Old 02-24-2009
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Pillow stuffing? What is that? I wanted more airspace so the base will carry out more, before it had .9 cu. ft of space, now it sould have about 1.5, maybe less, but defintly more than .9 before it was just like "bop bop bop" instead of the "boooommm baboooommm boooooomm" that I want, which is what it was like in my celica. So hopefully the extra airspace helps a little. Will the pillow stuffing add more baboooooooom or more bop? LOL i hope that makes sense to you I dont know how else to explain it.
Also, how about spray painting over the carpet?
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  #29  
Old 02-24-2009
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The last time I checked 280W X 2 = 560W!!!
By those specs in the real world, RMS bridged power at 8ohm should be 440w, not half of 560w, which is why I call BS on PA's specs.
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  #30  
Old 02-24-2009
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Originally Posted by rizoss16 View Post
Pillow stuffing? What is that? I wanted more airspace so the base will carry out more, before it had .9 cu. ft of space, now it sould have about 1.5, maybe less, but defintly more than .9 before it was just like "bop bop bop" instead of the "boooommm baboooommm boooooomm" that I want, which is what it was like in my celica. So hopefully the extra airspace helps a little. Will the pillow stuffing add more baboooooooom or more bop? LOL i hope that makes sense to you I dont know how else to explain it.
Also, how about spray painting over the carpet?
Pillow stuffing effectively makes the box "larger" by changing the speed of sound inside the box and turning sound energy into heat and motion. Also, if the box is big enough, it helps prevent standing waves. Half a pound per cubic foot is usually where you get diminishing returns. So start by adding a little and keep going until you get to that number or until you are satisfied with the sound. :)
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  #31  
Old 02-24-2009
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Some added information!

You can hook up the amplifier as Bob/Takeda has suggested, but only if the signal is the same to both channels (Mono).

The voice coils are mechanically connected & driving each with a different signal (stereo) will ultimately end up in a catastrophic failure to either the voice coils or the amplifier.
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  #32  
Old 02-24-2009
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Some added information!

You can hook up the amplifier as Bob/Takeda has suggested, but only if the signal is the same to both channels (Mono).

The voice coils are mechanically connected & driving each with a different signal (stereo) will ultimately end up in a catastrophic failure to either the voice coils or the amplifier.
So long as you dont exceed the thermal limitations of the coil, you are fine. If it is the same signal out of phase, you are adding extra power with out adding any extra movement.

Best case scenario you lose loudness to the coils fighting one another and gain impedance due to the extra heat not being dissipated. Worst case scenario you blow the driver.

If they are 180 degrees out of phase you'll burn up the coil with a lot less power than rated and get almost 0 sound. That amp doesn't have L-R phase feature so you shouldn't have to worry too much if you do a stereo configuration on your mono subwoofer. However, as stated before, be very sure of the phase you hook up the coils in.
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  #33  
Old 02-24-2009
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  #34  
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Originally Posted by CBFranger View Post
By those specs in the real world, RMS bridged power at 8ohm should be 440w, not half of 560w, which is why I call BS on PA's specs.
WRONG AGAIN!!! Voltage is constant, doubling the impedance will cut the power in half, going from 4OHMS to 8OHMS....once again: P=V*V/R
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  #35  
Old 02-24-2009
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what is the technical name for pillow that stuff I want to order some
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  #36  
Old 02-24-2009
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what is the technical name for pillow that stuff I want to order some
Some call it poly fill. http://www.crutchfield.com/p_027808/...k.html?tp=1400
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  #37  
Old 02-24-2009
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Originally Posted by CBFranger View Post
So long as you dont exceed the thermal limitations of the coil, you are fine. If it is the same signal out of phase, you are adding extra power with out adding any extra movement.

Best case scenario you lose loudness to the coils fighting one another and gain impedance due to the extra heat not being dissipated. Worst case scenario you blow the driver.

If they are 180 degrees out of phase you'll burn up the coil with a lot less power than rated and get almost 0 sound. That amp doesn't have L-R phase feature so you shouldn't have to worry too much if you do a stereo configuration on your mono subwoofer. However, as stated before, be very sure of the phase you hook up the coils in.

Ummm ...... sorry but I don't understand the point you're trying to make?

Sounds like a lot of complexity for a simple subject.

The stereo signals for left & right are different. If you hook up the voice coils to different signals they will be in a constant struggle with each other, the speaker will sound like crap & eventually something's going to give.

Running a mono signal to both inputs of the amp will ensure that the same signal is output to both channels of the amplifier. As long as you connect both voice coils - to - & + to + they will be in phase.
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  #38  
Old 02-24-2009
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Originally Posted by Tee Rev View Post
Ummm ...... sorry but I don't understand the point you're trying to make?

Sounds like a lot of complexity for a simple subject.

The stereo signals for left & right are different. If you hook up the voice coils to different signals they will be in a constant struggle with each other, the speaker will sound like crap & eventually something's going to give.

Running a mono signal to both inputs of the amp will ensure that the same signal is output to both channels of the amplifier. As long as you connect both voice coils - to - & + to + they will be in phase.
Totally wrong! If each voice coil is in phase, there will be no problem in stereo! Going from mono to stereo does not change the phase of the signal between the two voice coils.

Maybe this will help you, the audio signal is made up of different frequencies, and amplitudes going to the same voice coil in a speaker. Do the different frequencies fight each other? NO....same thing with the stereo signals going to each voice coil IN PHASE. Matter of fact, you can put the amplifier in MONO, so each channel is receiving the same signal, and switch the polarity of one of the voice coils (180 degrees out of phase) and you shouldn't get any sound at all. The magnetic fields from each voice coil simply cancel each other out, there will be NO DESTRUCTION!!!!

Last edited by Takeda; 02-24-2009 at 05:54 PM.
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  #39  
Old 02-24-2009
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WRONG AGAIN!!! Voltage is constant, doubling the impedance will cut the power in half, going from 4OHMS to 8OHMS....once again: P=V*V/R
You are so dumb it's not even funny.
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  #40  
Old 02-24-2009
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Originally Posted by fddriver02 View Post
This.

Just go to walmart and pick up a bag in the craft section for a couple bucks.
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  #41  
Old 02-24-2009
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You are so dumb it's not even funny.
You can't get simple math correct, Einstein!!!

Ohm's law will be totally over your head!!!
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  #42  
Old 02-24-2009
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Originally Posted by Tee Rev View Post
Ummm ...... sorry but I don't understand the point you're trying to make?

Sounds like a lot of complexity for a simple subject.

The stereo signals for left & right are different. If you hook up the voice coils to different signals they will be in a constant struggle with each other, the speaker will sound like crap & eventually something's going to give.

Running a mono signal to both inputs of the amp will ensure that the same signal is output to both channels of the amplifier. As long as you connect both voice coils - to - & + to + they will be in phase.
Basically what all that goblegoop I posted means is, if the coils are pushing in the same direction at the same time, then you are OK. If they are pushing in opposite directions at the same time, you are wasting energy and could potentially damage the driver thermally (not covered under warranty, even if you were not exceeding the rated power levels).



AC signals going to your subwoofer look sort of like this. If one coil is the red line and the other coil is the blue line, they are slightly out of phase. At some points they are fighting one another. Imagine when the line is above 0 (the x axis) the coil is pushing the cone forward, when it is below the coil is pulling the cone backwards.
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  #43  
Old 02-24-2009
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You can't get simple math correct, Einstein!!!

Ohm's law will be totally over your head!!!
JESUS TIDDY BOPPING CHRIST!

220w @ 4ohm x 2, when bridged, will be 440w x 1 @ 8ohm.

When you bridge an amp, rail voltage is effectively doubled. Stop arguing subjects you do not understand.
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  #44  
Old 02-24-2009
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Originally Posted by CBFranger View Post
JESUS TIDDY BOPPING CHRIST!

220w @ 4ohm x 2, when bridged, will be 440w x 1 @ 8ohm.

When you bridge an amp, rail voltage is effectively doubled. Stop arguing subjects you do not understand.
TOTALLY WRONG!!! You have to use the bridged power spec @ 4 OHMS, you can't use the power spec in stereo mode due to the difference in the DRIVER impedances!!! So, once again.......bridged, 560WATTS at 4OHMS is going to be 280WATTS at 8OHMS!!!! The VOLTAGE IS GOING TO BE THE SAME WITH 4OHMS or 8OHMS!!!
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  #45  
Old 02-24-2009
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TOTALLY WRONG!!! You have to use the bridged power spec @ 4 OHMS, you can't use the power spec in stereo mode due to the difference in the DRIVER impedances!!! So, once again.......bridged, 560WATTS at 4OHMS is going to be 280WATTS at 8OHMS!!!! The VOLTAGE IS GOING TO BE THE SAME WITH 4OHMS or 8OHMS!!!
No, because the limitations of the amplifiers power supply are current based. This means that IF your transistors could handle it, you could run the ampt bridged at 2ohm but the power would not double because you are limited by current, meaning you would have to turn the voltage down.

Imagine the amplifier as a pool with a valve in it and there is hose constantly filling the pool. Eventually you can only go so big with the valve because if you go any bigger (lower impedance) you will run out of water.
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  #46  
Old 02-24-2009
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Originally Posted by CBFranger View Post
No, because the limitations of the amplifiers power supply are current based. This means that IF your transistors could handle it, you could run the ampt bridged at 2ohm but the power would not double because you are limited by current, meaning you would have to turn the voltage down.

Imagine the amplifier as a pool with a valve in it and there is hose constantly filling the pool. Eventually you can only go so big with the valve because if you go any bigger (lower impedance) you will run out of water.






I'm done!!
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  #47  
Old 02-24-2009
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OK, just because you read an article on Ohm's law and wired up a subwoofer or two doesn't make you an expert.

When you become a sponsored competitor with multiple university level physics, electronics, and mathematics classes you will understand what I'm saying and why I'm saying it.

Well you dont even need all of that, just read a bit more.

You're on the right track but you haven't made it over the mountain yet.
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  #48  
Old 02-24-2009
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Originally Posted by Takeda View Post
Totally wrong! If each voice coil is in phase, there will be no problem in stereo! Going from mono to stereo does not change the phase of the signal between the two voice coils.

Maybe this will help you, the audio signal is made up of different frequencies, and amplitudes going to the same voice coil in a speaker. Do the different frequencies fight each other? NO....same thing with the stereo signals going to each voice coil IN PHASE.

Holy crap you just like to argue don't you.



Think about it, it's a stereo signal IN PHASE. lets say that the right side is producing 120 hz at 20 watts, now lets say that the left side is trying to produce the same frequency at 100 watts because during the recording the bassist was standing on the left side of the stage. Now in reality this is happening throughout the entire frequency range that the speaker is trying to produce.

Do you honestly believe that this scenario is as good as having the same signal driving each voice coil?
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  #49  
Old 02-24-2009
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Originally Posted by Tee Rev View Post
Holy crap you just like to argue don't you.



Think about it, it's a stereo signal IN PHASE. lets say that the right side is producing 120 hz at 20 watts, now lets say that the left side is trying to produce the same frequency at 100 watts because during the recording the bassist was standing on the left side of the stage. Now in reality this is happening throughout the entire frequency range that the speaker is trying to produce.

Do you honestly believe that this scenario is as good as having the same signal driving each voice coil?
If the phase is the same, the component output of the driver will be the same reguardless.

However, say you can exceed the RMS power of that one coil pushing 100w (maybe the max RMS power was 80w) then yes, it will likely damage the driver. Or, for instance, you drive that channel into clipping and that clipping exceeds the maximum thermal capacity of the coil, you will likely damage the driver. :)
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  #50  
Old 02-24-2009
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Damn I am going to show my electronics professor this thread!!! lol!!!
Well I wired up the voicie coils to seperate channels and brought my box down to my work today and finished it. It sounds amazing compared to before. Pretty cool how one sub in a bigger box can sound so much better than 2 subs.
It is much louder and it can actually hit the low bass in rap songs.
No I just need to figure out how to tune the amp and head unit. The head unit has frequency options for bass and I have no idea what to use.
It does start to sound distorted when the volume is turned up on the head unit, even with the amp turned to 3/4 volume.
So I guess I will try that stuff. What is it called at walmart? It doesn't make sense to me it seams like a placebo affect type of thing, since it is actually taking up space, decreasing air space. But I will give it a try.
Any tips on tuning?
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