Decreasing Impedance Rise

[DooMRR]

Sorry if it is a long read, but I am trying to make it as simple to understand as possible.


Now those who compete in IASCA - IDBL will know that impedance rise can be a serious pain. With my previous SPL setup, I lost more than half the power of my amp, most of which was due to my impedance rising high from my subs. I think I came up over night on a way to ease the pain of this. I am guessing people probably already came up this idea and I'm not the first, but I don't think it was ever discussed here.

Now this solution works best with playing test tones for SPL. It can also work really well when it comes to playing songs with a constant non-stop bass line such as those that people use in IASCA - Bass Race. It can also be used by the gallery men, if any use songs with constant non-stop bass lines.

Impedance rise occurs whenever the speaker is playing. For example, you make have a 1ohm sub, but as it is playing, the impedance can rise to say 2 or 3ohms or even more. Usually building a small enclosure causes the sub to be better controlled, but causes the impedance of the sub to rise faster. The opposite occurs for a bigger enclosure.

For explanatory purposed, let us say we have:
- A sub wired to 1ohm
- Connected to a 10,000RMS amplifier, 1ohm stable
- Playing a test tone (constant frequency)
- And a good enclosure for the sub

I give the sub full volume and measure the current from the amp and the corresponding voltage. Using the formulas:
Power = (Voltage)(Current)
Voltage = (Current)(Resistance)
You can calculate the power the amp produces and the resistance of the sub. Now from my tests for my setup, the impedance use to rises from 1ohm to about 4ohms thus only allowing our 10,000RMS amp to producing about 4000RMS.

Because of impedance rise, that 10,000RMS amp @1ohm only produces 4000RMS @4ohms. That big powerful amp has just been seriously restricted.


The amplifier is rated at 1ohm stable, so placing a 0.5ohm speaker on the amplifier and turning it on is dangerous and can cause the amplifier to go into protection or even damage it. However, if you do get the amplifier to stay running and not damage itself long enough for you to give it some volume, when the sub begins to move, the impedance will begin to rise. The more power you give it, the higher the impedance will go up, soon passing the 1ohm mark reaching the safe operating zone for the amp. The reason for running it at 0.5ohms is so that when the amplifier is giving a lot of power, the impedance will rise to (for example) 1ohm. Whereas, if the sub was wired to 1ohm from the start, and you give it power, the impedance will rise to 1.5ohms. The lower the impedance of the sub, the more power the amp produces. So the point is, to set the beginning impedance of the sub as low as possible, so that when you give full volume, the impedance rises to at least 1ohm, or if greater than 1ohm, stays as close as possible to it thus allowing the amplifier to produce its rated power.

NOW THAT YOU UNDERSTAND THE THEORY, LETS LOOK AT...

THE SOLUTION:

The sub we will now be using has an impedance of 0.25ohms. Very low impedance, which will be dangerous for our 10,000RMS amplifier, stable at 1ohm. Let us say you get a resistor than can handle some good power. For example, this Milwaukee Ribwound resistor.
http://www.milwaukeeresistor.com/ribwound.html
It can handle up to 2000RMS and is a 1ohm resistor.
We can wire this resistor in series to one of the terminals of the sub going to the amplifier and also wire a switch in parallel with the resistor. See diagram below.



When the resistor is in series with the speaker and the switch is open, the total resistance is 1.25ohms, which is safe for our 1ohm stable amplifier. We can now safely turn on the amplifier. If we turn up the volume (Not more than 2000RMS of power. We don't want to burn the resistor), the impedance of the sub should begin to rise. It should rise to at least 2.25ohms. If not, a more powerful resistor will be needed so we can give the sub more power to raise its impedance some more. We can now set the switch to close on the resistor, thus shorting it out, and allowing the impedance of the sub to drop back down to 1ohm. So when we give the amp full volume, unlike last time when the impedance of the sub went up to 4ohms, it will now go up to say 3ohms. At 3ohms, the amp probably will put out about 6000RMS. That is a lot more power than before.
This solution would work better with 2 or more subs as you can parallel the subs bringing it down to a total impedance lower than 0.25ohms. The lower impedance you can wire your subs to, the better. It is a very simple theory, which I have not tried yet.




The reason why I said this will only work if you are playing a tone or music with a constant non-stop frequency is because after you short circuit the resistor and the bass stops (the speaker stops moving), there will be no impedance rise, so whatever impedance you wire your subs to, will be the impedance your amp will see. So if the subs are wired to an impedance lower than the rated impedance of the amp, you can damage the amp. Of course though, when you are lowering the volume, you will have to lower it enough to safely open the switch that is parallel to the resistor to raise the impedance of the subs. Also, you will need a very good switch to handle the current going to the speakers.


If there are any problems with my theory, please let me know. This came to me in the middle of the night and from my knowledge, it seems like it can work.

[cow-bat]

[silent_riot]

Slowly rolling the volume control up will do something like this, but will drain power quickly.

[fuzz_174]

Slowly rolling the volume control up will do something like this, but will drain power quickly.

Yup slow roll!

[DooMRR]

don't get me wrong eh but ent voltage x current is the apparent power (VA) the amp puts out,
the factors affecting the real power (W) that the sub uses will not only be impedance rise, but efficiency of sub, enclosure, heat loss in the coil.

Somehow u getting tied up between impedance and resistance. two different tings bro.

True. I agree with what you are saying, but this is the easiest way I know to get an estimate of the power from the amplifier. Power will be loss, but it still gives you a decent power entering the sub. I'm not really trying to be very accurate, but get some estimated values to work with just to show if there is a change. Also, even if I am lets say 1000RMS off in my measurement due to the errors, these errors will carry on in my experiment, meaning that all my calculations will have an error of 1000RMS. My values may be wrong, but the change should remain at least close to the same.

Impedance is the resistance of a component at a given frequency. This is why I was working with a constant frequency. It can also work with songs that has a constant, non-stop bass line. It's basically music with one frequency.

Slowly rolling the volume control up will do something like this, but will drain power quickly.

This is correct, but I still feel the gain in power from reducing the resistance will be more than the power loss in slowly turning up the volume. Also, I don't mean turning up the volume very slow. I mean turn up the volume as fast as possible, to lets say volume 40 on your deck, but when you reach volume 15 on your way up(where the amp produces about 2000RMS), close the switch. So you can also have a nice smooth roll up on the bass.

[- Rovin's car audio -]

lawrd all this reading boi

like i have to go open back my high school physics books to remember some of d words being used here yes .... ......

[SR]

slow yuh roll

learn yuh peak resonant freq

simplest way to avoid impedance rise for spl testing


but

ah like yuh thinking on this topic

[DooMRR]

lawrd all this reading boi

like i have to go open back my high school physics books to remember some of d words being used here yes .... ......

No. You know most of this already. I just gave a write up for anyone who doesn't know about it. In short, what I wrote before the solution is that when playing a test tone, the louder you play that tone, the impedance of the speaker(s) rises as high as 4ohms or even more. You can also use the formulas P = VI and V = IR to calculate power and resistance (in this case, impedance).

slow yuh roll

learn yuh peak resonant freq

simplest way to avoid impedance rise for spl testing


but

ah like yuh thinking on this topic

I already found my peak resonant frequency and I use to roll up the volume at a decent speed (still don't understand how rolling up the volume slowly decreases impedance rise but it did help with my score), but I still got high impedance rise. So I had to come up with another way to solve this.

[- Rovin's car audio -]

nah i was j\k & not making fun of anything or anybody ...

believe it or not even as "a seasoned competitor" i still have alot to learn too & im still learning


im doing a bunch of stuff in work right now so later tonight i will take a good read .....

[3stagevtec]

I see no flaws in your logic..

Here's a nice suggestion, instead of looking for a 2000W resistor, why not use a 1ohm coil from a high end subwoofer as a resistor (i.e. just the coil alone).. most high end sub coils can easily 2000W+ for a burp, is relatively cheap and easy to access.. you can even fluid cool the thing to handle more power..

then all you have to do is short out the external coil..

[3stagevtec]

The problem he is trying to avoid is starting an amplifier on a 0.25ohm load.. for example..

[DooMRR]

I see no flaws in your logic..

Here's a nice suggestion, instead of looking for a 2000W resistor, why not use a 1ohm coil from a high end subwoofer as a resistor (i.e. just the coil alone).. most high end sub coils can easily 2000W+ for a burp, is relatively cheap and easy to access.. you can even fluid cool the thing to handle more power..

then all you have to do is short out the external coil..

That. Makes. So. Much. Sense.
So, replace my sort of expensive resistor with any coil that can handle some good power. A simple 1000RMS coil can handle 3000RMS easily for a short time long enough for you to close the switch and short out the coil.

[noyztoyz]

you're assuming the powerful 1 ohm amplifier wont turn on normally with the 0.25 ohm load.
I think it will though, most of them will normally
Only if you had a amplifier that was giving this problem you would resort to the ideas put forward here,

U were think bout this in your sleep????

[SR]

no noyznoyz


take a read

The impedance is the resistance of the coil when AC is applied. Since the coil acts like an inductor, the impednace changes with frequency.

What people call impedance rise is due to the woofer being put in a box. If you look at the impedance plot of a woofer in free air, the impedance rises at the resonant frequency of the driver. Once in the box, the cone has a different reaction with pressure behind it, which can change the impedance plot. You also have new impedance spikes due to the box size, port tuning, etc.

Impedance rise may in fact not even be a higher impedance at all frequencies (more than likely will be an increase in the overall average, but the spike at the driver's resonant frequency may still be the highest impedance). Many times it is just additional humps/spikes in the impedance plot, or even changing of the impedance spike seen with the woofer in free air. For someone playing music, the additional humps/spikes will increase the average impedance seen while playing music. For someone burping at a single frequency, they need to know the impedance at their frequency to match the amp to the sub. There is a good chance the impedance will be higher near the frequency they burp at, since it not far above port tuning.

For the average person, ignore "impedance rise". The hardcore competitor uses the actual true impedance to his advantage to get all the power he can from the amps

taken from this forum
http://www.stevemeadedesigns.com/board/ ... ance-rise/

[SR]

you're assuming the powerful 1 ohm amplifier wont turn on normally with the 0.25 ohm load.
I think it will though, most of them will normally
Only if you had a amplifier that was giving this problem you would resort to the ideas put forward here,

U were think bout this in your sleep????

eh

[SR]

winisd is a nice free prgram that s has a graph showing impedance rise

doenst take into consideration and some other factors that cant be included in the software analasys but will give an idea on the box design

[Brian Steele]

winisd is a nice free prgram that s has a graph showing impedance rise

WinISD's predictions can all but be ignored for high SPL systems. WinISD, and many other box design programs are based on t/s parameters, which are by definition SMALL signal parameters, defining the driver's characteristics when driven by signals around 1W, or less than 0.001% of the power level of most SPL systems.

However, if you've got a good idea of how those parameters shift as power is increased, WinISD (and other t/s parameter based tools) can be useful to "get you into the ball-park".

Also, there's two impedance rises to be considered here. One is based on the alignment and the driver's t/s parameters (and can be predicted by WinISD at low power levels). The other is the impedance increase caused by increased power applied to the driver's voice coil (as the coil heats up, its impedance will rise). I got the impression that the originator of this thread was attempting to address the effects of the latter.

[silent_riot]

I see no flaws in your logic..

Here's a nice suggestion, instead of looking for a 2000W resistor, why not use a 1ohm coil from a high end subwoofer as a resistor (i.e. just the coil alone).. most high end sub coils can easily 2000W+ for a burp, is relatively cheap and easy to access.. you can even fluid cool the thing to handle more power..

then all you have to do is short out the external coil..

I don't think the coil will handle 2000w all by its lonesome. It isn't moving any air for cooling as it would in a motor. To me, it sounds the same as passing 2000W DC through the coil.
I still have reservations about playing with the output of an amplifier while it is putting out thousands of watts.

[silent_riot]

Maybe an amp manufacturer can chime in on the behaviour of amplifier protection circuits when their output load is halved at high power....somehow I thinking most amps will go into protect with that sudden increase in current due to that switch mechanism.

[DooMRR]

you're assuming the powerful 1 ohm amplifier wont turn on normally with the 0.25 ohm load.
I think it will though, most of them will normally
Only if you had a amplifier that was giving this problem you would resort to the ideas put forward here,

U were think bout this in your sleep????

From my knowledge, turning on an amp with it connected to a resistance lower than its recommended stable load could cause most to go into protection to protect its circuits. Also, I am pretty sure that for most amps, even if you managed to get it to turn on, and stay on, when you begin to turn up the volume, it will trip into protection. I know some amps like the Sundown 1500d, you can run them at 0.5ohms (not recommended), but going lower usually causes them to trip, and I am 100% sure it is not safe to do this. There has to be a reason it is rated as a 1ohm stable amplifier and not less.
Also, if I have a 10,000RMS amplifier that I paid big money for, I don't know about you, but I would be seriously worried to be starting that thing up with a resistance lower than its rated value. Just not worth the risk.
My solution is to allow me to end up with a final impedance close to the rated value of the amp upon given full power by allowing me to safely start off with an extremely low resistance from the subs.

As for thinking of this in my sleep. I was actually trying to sleep and the thought of why the big amp I used for SPL wasn't producing full power. I then tried to come up with a solution to solve this. I fall asleep while studying, why not try taxing my brains to fall asleep.

Also, there's two impedance rises to be considered here. One is based on the alignment and the driver's t/s parameters (and can be predicted by WinISD at low power levels). The other is the impedance increase caused by increased power applied to the driver's voice coil (as the coil heats up, its impedance will rise). I got the impression that the originator of this thread was attempting to address the effects of the latter.

That is correct. I already had my enclosure working well and the subs I had were bought on a very low budget. It was the best (and most powerful because I was going to use a lot of power) I could find for the price. I wanted to reduce the impedance rise of the subs when they were under heavy power.

I don't think the coil will handle 2000w all by its lonesome. It isn't moving any air for cooling as it would in a motor. To me, it sounds the same as passing 2000W DC through the coil.
I still have reservations about playing with the output of an amplifier while it is putting out thousands of watts.

Maybe an amp manufacturer can chime in on the behaviour of amplifier protection circuits when their output load is halved at high power....somehow I thinking most amps will go into protect with that sudden increase in current due to that switch mechanism.

Remember, the external coil by itself will only be active for a 2 or 3 seconds. So yes it will heat up much faster, but it isn't running as long if you are playing music. I never played with a coil out of a motor, but I believe it will be able to handle that power for the short time.
As for the the amp going into protection due to the sudden increase in current, I get what you are saying. It had me thinking and isn't it the same as just pausing the test tone on the radio, turning the volume all the way up and then un-pausing the track? That will send a much bigger surge of power through the amp than my switch mechanism. This does not cause the amp to trip into protection. Also, remember that when the impedance drop occurs, the amp will not be under full power so it is not like I am pushing the amplifier and messing around with it.

[noyztoyz]

you're assuming the powerful 1 ohm amplifier wont turn on normally with the 0.25 ohm load.
I think it will though, most of them will normally
Only if you had a amplifier that was giving this problem you would resort to the ideas put forward here,

U were think bout this in your sleep????

From my knowledge, turning on an amp with it connected to a resistance lower than its recommended stable load could cause most to go into protection to protect its circuits. Also, I am pretty sure that for most amps, even if you managed to get it to turn on, and stay on, when you begin to turn up the volume, it will trip into protection. I know some amps like the Sundown 1500d, you can run them at 0.5ohms (not recommended), but going lower usually causes them to trip, and I am 100% sure it is not safe to do this. There has to be a reason it is rated as a 1ohm stable amplifier and not less.
Also, if I have a 10,000RMS amplifier that I paid big money for, I don't know about you, but I would be seriously worried to be starting that thing up with a resistance lower than its rated value. Just not worth the risk.
My solution is to allow me to end up with a final impedance close to the rated value of the amp upon given full power by allowing me to safely start off with an extremely low resistance from the subs.

As for thinking of this in my sleep. I was actually trying to sleep and the thought of why the big amp I used for SPL wasn't producing full power. I then tried to come up with a solution to solve this. I fall asleep while studying, why not try taxing my brains to fall asleep.

what big mono u have?
i think it depends on the method of the protection circuitry of the amplifier

[Casadoma]

sound like you need a power regulator

[southside connections]

hmmm

adt uses this same method in out passively crossed stage monitors,small line arrays and stand alone boxes

the resistor is used to create a linear impedance , before the speaker, so the passive crossover sees a consistent, never changing load(coil movement, impedence rise from heat, non linearity and a few others are sorted out here)

this in turn, flattens out power distribution among frequency

this is known as a zobel circuit, but from what i'm seeing, while you are compensating for the amplifier, you are not for the speaker, and while the resistor gets the amp a consistent load, the other half needs something to balance out what you would normally lose in heat with your resistor, in other words,you are missing a piece there

imo, while all this seems nice, it's a general waste of time and money, as sr said, get the r/sf(fo) of the vehicle correct, burp for the time needed and you would not have much to worry about, because the only time impedance rise should affect you is when burp it consistently, which would only happen when testing while at home and not in competition

[3stagevtec]

you're assuming the powerful 1 ohm amplifier wont turn on normally with the 0.25 ohm load.
I think it will though, most of them will normally
Only if you had a amplifier that was giving this problem you would resort to the ideas put forward here,

U were think bout this in your sleep????

From my knowledge, turning on an amp with it connected to a resistance lower than its recommended stable load could cause most to go into protection to protect its circuits. Also, I am pretty sure that for most amps, even if you managed to get it to turn on, and stay on, when you begin to turn up the volume, it will trip into protection. I know some amps like the Sundown 1500d, you can run them at 0.5ohms (not recommended), but going lower usually causes them to trip, and I am 100% sure it is not safe to do this. There has to be a reason it is rated as a 1ohm stable amplifier and not less.
Also, if I have a 10,000RMS amplifier that I paid big money for, I don't know about you, but I would be seriously worried to be starting that thing up with a resistance lower than its rated value. Just not worth the risk.
My solution is to allow me to end up with a final impedance close to the rated value of the amp upon given full power by allowing me to safely start off with an extremely low resistance from the subs.

As for thinking of this in my sleep. I was actually trying to sleep and the thought of why the big amp I used for SPL wasn't producing full power. I then tried to come up with a solution to solve this. I fall asleep while studying, why not try taxing my brains to fall asleep.

what big mono u have?
i think it depends on the method of the protection circuitry of the amplifier

he's just generally speaking..

the external coil can also be liquid cooled.. there are non conductive liquids that are used to cool transformers etc that would work great in this situation..

[DooMRR]

this is known as a zobel circuit, but from what i'm seeing, while you are compensating for the amplifier, you are not for the speaker, and while the resistor gets the amp a consistent load, the other half needs something to balance out what you would normally lose in heat with your resistor, in other words,you are missing a piece there

imo, while all this seems nice, it's a general waste of time and money, as sr said, get the r/sf(fo) of the vehicle correct, burp for the time needed and you would not have much to worry about, because the only time impedance rise should affect you is when burp it consistently, which would only happen when testing while at home and not in competition

What you said is true. I am trying to solve the issue of the impedance rising high when playing a test tone. I am doing some reading to try and understand more about T/S parameters and what I can gather is that a speaker with a higher T/S parameter would be better suited for a case like this (Correct me if I am wrong on that).Yes, as I am testing, the sub coil heats up, the resistance will increase.
This is the problem for me, and I guess anyone with massive power. I had two weak-ish 10" subs and I wanted to put more than 3 times the power on them that they were rated for. Now they use to heat up a little on the 1st play on full power, so that will naturally increase the natural resistance of the speakers, so I can't do anything about that. I was also playing at the resonant frequency of the vehicle and the tuning frequency of the enclosure to control the subs at that high power. So when I did my testing resistance on the 1st time while it was playing at full volume, I found my resistance to rise from 1 to over 4ohms. This impedance rise was killing all my power. Now I am still not sure what more I can do to control the rise in impedance from the speaker via box design (keep in mind I still need to control the subs due to the high power. Don't want the coil to go jumping out of the basket).
Can you give me a little more information on this?
I also use to roll up my volume slowish.

sound like you need a power regulator

Something to regulate power? You mean something to tell me when i reach about 3000RMS before I short circuit the resistor (coil)? I was just going to do a simple measure of voltage and current and calculate the power. Just need to know what volume number on the deck I have to reach when I am outputting about 3000RMS. Is this what you are referring to?

what big mono u have?
i think it depends on the method of the protection circuitry of the amplifier

You are still sort of missing my point. I basically want to wire my subs as low as 0.25ohms and I don't know, maybe strap two 1ohms stable amplifiers to it. I am trying to get my initial resistance of the sub as low as possible so that when the impedance does rise, it doesn't go up as high as 4ohms. You probably have a monster of an amp that you can trust turning on at 0.25ohms and turning up the volume without worry of damaging the amp, but in my case, no matter how good the manufacturer says their amp is built, I'm not willing to take that risk. No matter what type of protection circuitry you have on an amplifier, I am sure it was not designed to operate safely at that low levels. Else, as I said, it wouldn't be rated as a 1ohm stable amplifier.

[southside connections]

well you are missing the capcitor for the zobel circuit , but what you are looking for is pretty expensive, the most expensive one we use costs around $65 usd, for 630v, which are usually metalized polypropylene

630v peak rating, the actual long term handling is around and usually 1/2 that, so let's say 315v, at 8ohms = 2250wmax, and then to find a resistor to match this is usually too expensive

what you can do, buy and series, or parallel , and work your way from there, the cap will create the necessary extra, so when your speaker's impedance rises, the cap will balance out the power shortage accordingly , but it is inductance(le) specific , so one does not work for all


but even so, there is still going to be losses , so if you would like, give it a try, you may surprise yourself with the results

[doublestenns]

problem:
let's say u get pass the 2000 watts mark and u short your resistors the load the amp sees drops from
4.25 ohms to 1 ohm and everythin goes well,you continue to raise the volume and by accident u clip the amp,what would happen hear is portions of the sine wave would be cut causing small shots of direct current to flow.

because there is no cone movement your impedance drops back to .25 ohms
and everythin goes boom. now a good amp might survive as the direct current only comes in
where the wave is clipped

possible solution
circuit breakers?


ok so hear how the system could better be setup.
the 10000 watts rms amp should have connected to it's output an ammeter clamp and a volt meter
following ohms law 100*100=1000
so 100 amps is the safe amount of current the amp could handle
so a 100 amp breaker should be used.
next would be the coils , 4 liquid cooled 1ohm coils in series and parallel with another breaker between them.

as the volume is turned up u can turn close the breakers one by one (the two in the middle that is) this way you have more flexibility and safety.
the only thing remaining to is calculate every thin usin ohms law an p=vi,
(i too lazy u go do dat)

[DooMRR]

well you are missing the capcitor for the zobel circuit , but what you are looking for is pretty expensive, the most expensive one we use costs around $65 usd, for 630v, which are usually metalized polypropylene

630v peak rating, the actual long term handling is around and usually 1/2 that, so let's say 315v, at 8ohms = 2250wmax, and then to find a resistor to match this is usually too expensive

what you can do, buy and series, or parallel , and work your way from there, the cap will create the necessary extra, so when your speaker's impedance rises, the cap will balance out the power shortage accordingly , but it is inductance(le) specific , so one does not work for all


but even so, there is still going to be losses , so if you would like, give it a try, you may surprise yourself with the results

I'm not trying to build the "zobel" circuit. I'm only making a cheap rip off. I'm not really trying to keep it at exactly 1ohm (if the amp is 1ohm stable), but at least lower the final impedance the amp will be seeing when playing a tone. It would only cost you a speaker coil (and two circuit breakers if you read what I type next).

problem:
let's say u get pass the 2000 watts mark and u short your resistors the load the amp sees drops from
4.25 ohms to 1 ohm and everythin goes well,you continue to raise the volume and by accident u clip the amp,what would happen hear is portions of the sine wave would be cut causing small shots of direct current to flow.

hard-clip.png

because there is no cone movement your impedance drops back to .25 ohms
and everythin goes boom. now a good amp might survive as the direct current only comes in
where the wave is clipped

Yes. This makes sense. So I guess my design is flawed if one were to clip the amp.

possible solution
circuit breakers?


ok so hear how the system could better be setup.
the 10000 watts rms amp should have connected to it's output an ammeter clamp and a volt meter
following ohms law 100*100=10,000
so 100 amps is the safe amount of current the amp could handle
so a 100 amp breaker should be used.
next would be the coils , 4 liquid cooled 1ohm coils in series and parallel with another breaker between them.

resistors.JPG

as the volume is turned up u can turn close the breakers one by one (the two in the middle that is) this way you have more flexibility and safety.
the only thing remaining to is calculate every thin usin ohms law an p=vi,
(i too lazy u go do dat)

I like this idea. Will first need to determine how much current draw the amp will use to produce full power. This is easy enough to calculate. In our example:
10,000RMS @14.4V
P = VI
10,000 = (14.4)(I)
I = 695A
You can probably find the current draw of the amp on its website if the maker writes it in.

So we will need a 700A breaker to connect to the amplifier input terminal so if the amp were to clip, thus pulling more current, thereby tripping the breaker.

Now the problem with this calculation is, the voltage never stays at 14.4Volts, and the final impedance would not be at 1ohm. It should be more. We will have to estimate a voltage drop, being reasonable, say 12.0V. That sort of solves the voltage problem.
The next step is to get a reasonable value for the impedance upon playing at full power to calculate the current draw. For the better experienced electrical guys, tell me if I can do this. Connect the amplifier like normal and play it at full volume. Measure voltage and current and calculate the final impedance. Let is say it rises from 1ohm to 4ohms. That is a 3ohm impedance rise. Can you wire it down to 0.25ohms and assume it will rise to 3.25ohms or something close to that? Or is there some way you can calculate it?

For now, let us assume that the impedance will rise to 3ohms when the external coils are connected and the voltage will drop to 12Volts. Websites usually post how much power their amplifier produces at different resistances, so for our amp in use, let us assume it produces 4000RMS @12V and 3ohms.
Using P = VI,
Current draw, I = 333A
So we need something like a 350A circuit breaker.
That should trip when the amp begins to clip and pull more current.

As for your suggestion on adding other breakers between the external coils for better control, that can work too. But I feel one breaker to short the coil(s) out will be good enough. Don't want to put too much 'breaks' in the system to increase power loss due to wires.
Nice suggestion!

[doublestenns]

ok so hear how the system could better be setup.
the 10000 watts rms amp should have connected to it's output an ammeter clamp and a volt meter
following ohms law 100*100=1000
so 100 amps is the safe amount of current the amp could handle
so a 100 amp breaker should be used.

the 100 amp breaker would be going on the output of the amp
because , to get 10000 watts at 1 ohm the amp would have to produce 100 volts
and 10000/100 =100 amperes.

this would provide more protection as well built amps have a lot of capacitors
which store enough energy to damage an amp before it starts to draw loads of current

besides where u gettin a 700 amp breaker that would not kill u pocket

[jeff]

spl comp and music playing is different

As any spl competitor would know, all the theories and formulas in the world just seem to make no sense when you burp a system.

cvt 7 i have a solution for you that will solve this......get a 30000w amp