High Current, High Voltage, Impedance.

[[DANGERDAN]]

Hows it guys im back again and im hoping this will be the last investigation i need help with, iv spent quite a bit of time now researching about the fundamental physics for electricity to understand how speakers work in regards to its electrical side and further improve my understanding for future improvements and knowledge.

I understand almost how electricity works after reading many articles on the scientific descriptions for electricity physics, i just have a few hicups in getting my head around a few things but its not specifically with electricity its with amps and speakers and mostly impedance.

I understand that a speaker determines the load of the signal (impedance) so depending on the excursion and the difficulties of the specific frequency depends on how hard it is to drive and what load a speaker will have.
I don't know a specific question to help me understand this as i think there are a more than one so i will try my best to ask them.
High current amps vs high voltage amps ?
What relation does low impedance have with these two types of power supply.
In relation to impedance the law states that the lower the resistance the more power is available to flow through, current is measured in amps and amps relate to the rate of flow. What im confused at is the way the electrons are traveling, For eg with the amps measurement that just measures the rate of flow from one point.
Il try do some math to explain myself.
10 volts x 10 amps = 100 watts
20 volts x 5 amps = 100 watts
Is there a difference in the rate of flow (electron speed) and the amount of electrons (high flow) that we miss out when measuring amps.
When impedance is lowered from say 8ohm to 4ohm what fills the gap for this resistance, does the amps increase in the flow or does the voltage or from what my testing shows me that they both increase ?
Are high current amps better for low impedance dips or can high voltage push supply whats needed for these dips ?.

If there's any articles you could provide me to help me with this impedance issue i would be greatful and im sorry if i don't make sense, again thanks.

[-=DouglasteR=-]

I have the same questions !

It's the same about the toroydal transformers inside a lot of sound devices, it can generate a "High flow" o amps to the drive in a second. But this is important because of the power it provides or because of the speed that it generate it ?

A lot o questions :(

[Nanometer]

High voltage Vs. high current. That's a good question, and there's a big difference between the two. High Voltage amps for the speaker world are really referred to as signal amplifiers. They are capable of taking an input signal from a source and amplifying the signal to a level of your choice. A power amplifier is what drives the speaker. It supplies all the needed power that the speaker will use. A signal amplifier supplies a very small current and is not up to the task of supplying the needed current to power a normal home speaker. Because of speaker requirements, a high current power amp is needed. These amps are usually large and will dissipate a lot of heat.
What relation does low impedance have with these two types of power supply?
Only one of these amplifiers use a lot of power, the power amplifier. And as far as the resistance goes, I do not know the answer to that. What I can tell you is that the basic op amp has a high resistance, and a power amp has a lower resistance which causes it to use more power. So in relation I think a power amp has lower resistance, and a signal amp has very high resistance.


Is there a difference in the rate of flow (electron speed) and the amount of electrons (high flow) that we miss out when measuring amps?
Not sure what you mean. :(

When impedance is lowered from say 8ohm to 4ohm what fills the gap for this resistance, does the amps increase in the flow or does the voltage or from what my testing shows me that they both increase ?

Sounds to be right. A lower resistance will force more amperage for a certain voltage. This in turn means more power at the sacrifice of your supplying available power.

Are high current amps better for low impedance dips or can high voltage push supply whats needed for these dips?

High current amps are the only parameter that will help level a frequency output. Putting strain on the power amp will cause clipping distortion and sound artifacting. Voltage will fluctuate naturally through a speaker frequency range, but the current is what drives the speaker for loud outputs, not the voltage. Think of the signal amplifier as the voltage amplifier, and the power amp as the power supplier. The power amp works as the slave amplifier and only does what the signal amp tells it to.

[OldChap]

A bit over simplified but does this help you understand any better??? http://www.bcae1.com/hcvsnohc.htm

another quote..

A high-current amplifier is simply one in which the power supply and output stage can pass enough current to drive low-impedance loads. The "high-current" label is pretty much a marketing label, it gets tacked onto even entry-level receivers with slightly beefier power supplies than one usually sees at that level, but not much else (there is still only one pair of output transistors per channel, driving low impedance loads with a single pair can push the transistors out of their safe operating area - this is why many receivers have a "4-ohm" mode, it limits the supply rails and engages current limiting in the output stage to keep from blowing outputs.) When an amplifier attempts to swing a given voltage into the load, the load will attempt to draw a certain amount of current, and if the power supply cannot provide it or the output transistors cannot safely pass that current, output either sags (and the amplifier clips, and you can toast your tweeters if the distortion harmonics are strong enough) or you toast outputs (and if the protection circuit doesn't trip, possibly your woofers as well since up to 30-50VDC could pass through whichever transistor shorted to the speakers.)

To deliver large amounts of current, you need a beefy power supply, multiple output device pairs, and GOOD heat sinking. The amplifier can be class A, AB, B, D, whatever...the physics still apply. Also, you really can't divorce power in watts from current in amperes, since P = IE (P is power in watts, I is current in amperes, E is potential in volts.) If an amplifier cannot deliver the current a speaker asks for, the power in watts dissipated into the load will not be there either.


Those big heavy amplifiers that seem to cost a lot are mainly so because of the power supplies. the ability to supply all that power without voltage sag (droop/drop) is what sorts the men from the boys in amps and the reason why some prefer to use pre and power separates

[little_scrapper]

IMPORTANT!! Match the speakers impedance (Z) to the output impedance of your amplifier. Your amplifiers output will have an output impedance of say 8 ohms or 4 ohms for example. Im sure you have heard the term "impedance matching". Too low an impedance will result in weak output and poor tone. If you have an 8 ohm output on your amp, you want to use 8ohm speakers. If you have a 4ohm output you want to use 4ohm speakers.

Matching the impedance means that you are delivering the maximum power (volume) to the load (the speaker).

Also remember that if your connecting more than one speaker to an output you will be changing the impedance characteristics of the load. Two 8 ohm speakers in parrallel = 4 ohms of impedance. 3 in parallel = like 2.6ohms.

"When impedance is lowered from say 8ohm to 4ohm what fills the gap for this resistance, does the amps increase in the flow or does the voltage or from what my testing shows me that they both increase ?" The voltage output (amplitude) of your amplifier is controlled by the volume knob. if say the voltage output is 16 volts and the speaker is 8 ohms, that 2amps output (current = Volts/ohms). You put another 8ohms speaker in parrallel the Z is now 4ohms and the current just doubled. If you load it down too far yes the voltage and start to drop out because the amp is not able to deliver enough current. if your amp can only put out a max of 5 amps, and you have a 4 ohm speaker, and you feed it a pure tone, no matter how far you turn up the volume it wont go over 20volts because volts = amps x ohms.

Other factors to keepin mind:

Dont try to power an 800 watt amp with 8 gauge wire. hehe 8 awg willl burn up at 400 watts. If all you got is 8 awg then you best have a 30 amp fuse on it or youll start a fire. :)

lets say you want to run 4 speakers in one cabinet. If you have an 8 ohm amp, you can run series/parallel. The 2 sets of 2 (8 ohm) speaker in series = 16 ohms for each series. Run the second series in parrallel with the first, and that drops it back down to 8 ohms again. google it if you dont know what I mean.

If you have a 16 ohm amp, you can run 4x 4ohm speakers in series but if one fails all stop working.

[STEvil]

High Voltage amps were more popular/common (and are required for) electrostatic/planar speakers and field coil motor based speakers (an electromagnet in place of the normal magnet).. and plasma speakers too I guess.

Todays coil driven diaphragm speaker technology sticks with what the amplifier can produce which is called "high current" amplification because the voltage can technically be anywhere from 1 volt to 150+ volts, though most amplifiers only make up to 20-40 volts.

[[DANGERDAN]]

@nano, By signal amplifier i presume you mean the op amp which is the voltage amplifier inside the power amp ?.
I understand most of whats been said i had already read the high current article that was posted but i am thinking a little past all of whats been said.
Let me ask another question that might help me, Say we had a 8ohm speaker that dips down to 3-2ohms and say you had a amp that could supply 300watts into 8ohms but no lower ( and for the sake of being safe it had a 8ohm tap ).
Now why couldn't the speaker take the power it needs from 8ohm if the impedance dips ( change ) was to require more power why not take all from that level of impedance.
Obviously it doesn't so that's why i ask about high current vs high voltage because you can supply the same amount of watts whether its from high voltage and low current or low voltage and high current, the difference seems to be that there's something other than power (watts) that's needed when the impedance dips.
Meaning when the impedance dips its not the power its looking for its the current ( more electrons ) now why is it needing these high current electrons ?? How good are valve amps with impedance i heard that they don't like low impedance is this because its a high voltage output ?

Lets try one more example
power amp specs:
20 volts (seems to be average)
5 amps
100 watts from ( V x I = W )

Now from this can you work out the lowest this amp can supply into a impedance ? also when the speaker is resisting at 8ohms and dips to 4ohms what exactly is it resisting ? i presume its the amps and that's where the extra power comes from ? or does it resist both volts and amps ( i have a digital polimeter which i have been using for studies ).



I sure hope you understand where im coming from cause im going mental haha love you all thanks again.

[Nanometer]

@nano, By signal amplifier i presume you mean the op amp which is the voltage amplifier inside the power amp ?.

Not exactly, a signal amplifier is separate from the power amp, and if you have a separate setup the signal amp will be in the preamp.

I understand most of whats been said i had already read the high current article that was posted but i am thinking a little past all of whats been said.
Let me ask another question that might help me, Say we had a 8ohm speaker that dips down to 3-2ohms and say you had a amp that could supply 300watts into 8ohms but no lower ( and for the sake of being safe it had a 8ohm tap ).
Now why couldn't the speaker take the power it needs from 8ohm if the impedance dips ( change ) was to require more power why not take all from that level of impedance.

A good amplifier can handle as low as 2 ohms sometimes. Some car amplifiers often rate their systems as 1 ohm capable. A normal receiver that handles 8 ohm speakers can't handle the power load that would occur if the speakers were in a 2 ohm range. It has to do with a limitation on the amplification system. If the power to drive the speaker isnt there, you risk a burn out from power draw that exceeds specifications.

Obviously it doesn't so that's why i ask about high current vs high voltage because you can supply the same amount of watts whether its from high voltage and low current or low voltage and high current, the difference seems to be that there's something other than power (watts) that's needed when the impedance dips.
Meaning when the impedance dips its not the power its looking for its the current ( more electrons ) now why is it needing these high current electrons ?? How good are valve amps with impedance i heard that they don't like low impedance is this because its a high voltage output ?

Because Power is based on I*V it is actually pretty accurate to say that more power needs more current. The thing is all of these are all related, one affects another. P=I^2*R=IV What does stay consistent is the voltage that is supplied through the power amp. The power amp boosts the power by supplying an amperage that compensates for the speaker's impedance.

Lets try one more example
power amp specs:
20 volts (seems to be average)
5 amps
100 watts from ( V x I = W )

Now from this can you work out the lowest this amp can supply into a impedance ? also when the speaker is resisting at 8ohms and dips to 4ohms what exactly is it resisting ? i presume its the amps and that's where the extra power comes from ? or does it resist both volts and amps ( i have a digital polimeter which i have been using for studies ).

The lowest the amp can supply? I'm not sure what you mean. When the power amp becomes over loaded, the voltage will start to dip to compensate. The volume does not get louder, but this stresses the components. Here is where you risk over current draw.

I sure hope you understand where im coming from cause im going mental haha love you all thanks again.

I hope I answered something :-X

This setup below shows a pre amp on top, and a power amp below. Because of power demands the size of the power amp is much larger.

PreAmp and Power Amp (http://media.audiojunkies.com/mccormack-ld-2-preamp-dna-250-power-amp.jpg)

[[DANGERDAN]]

@nano, By signal amplifier i presume you mean the op amp which is the voltage amplifier inside the power amp ?.
Not exactly, a signal amplifier is separate from the power amp, and if you have a separate setup the signal amp will be in the preamp.
I was under the impression that the preamp has a op amp and its main use is for the control of the signal not really to help with voltage, the main power amp is more than enough capable to supply enough voltage from what i can see they reach up to 30v's quite easy.

A good amplifier can handle as low as 2 ohms sometimes. Some car amplifiers often rate their systems as 1 ohm capable. A normal receiver that handles 8 ohm speakers can't handle the power load that would occur if the speakers were in a 2 ohm range. It has to do with a limitation on the amplification system. If the power to drive the speaker isnt there, you risk a burn out from power draw that exceeds specifications.
I already understand all of this but this doesn't answer my question as to why this impedance change is important, current is not power it carries power and it is a combination of current x volts that creates power.
Current to me seems to be needed for low resistance so the more current you have the better you it can handle.
Most of this is best guess but i don't think voltage is constant and nor is current because of resistance, as the excursion changes due to the frequency the impedance changes and the impedance is just a efficiency change so with that when more power is needed the efficiency of the speaker changes. Electrons in a high voltage source move in a smaller line but really fast and in a high current source there are more electrons together but move slower, with the right combination they will provide the same power but with different applications they give a different effect.

Because Power is based on I*V it is actually pretty accurate to say that more power needs more current. The thing is all of these are all related, one affects another. P=I^2*R=IV What does stay consistent is the voltage that is supplied through the power amp. The power amp boosts the power by supplying an amperage that compensates for the speaker's impedance.
This doesn't sound right to me, when you say more power needs more current you are indicating that current needs to be raised for more power and that volts are consistent but they really are not, it depends on what your talking about but if you were talking about speakers it still wouldn't be a solid voltage level.
Power plants run 1 million volts and only 1 amp to a transformer this was considered the easier way to transfer power instead of 1 million amps and 1 volt as this would create a lot of heat dissipation, power loss and would require a much bigger cable. This is the difference im looking at "high voltage, high current" if you consider 1 million volts x 1 amp to be high current i think your incorrect, from my testing with a digital multimeter when you scan through the frequency range from 20hz to 20khz the voltage and the amps are constantly changing so im guessing the resistance is causing this change, volume is derived from the power output (watts) so the more watts you have the louder its going to be.
Amps can fail in two ways either by overheating from excessive load from a speaker or fails to provide stable power for the signal and starts clipping the signal and potentially harms the speaker coil.
But isn't there a max output on amps from the transistor ?? like my amp ( marantz sr4320) from best guess has about 4 amps is 80 watts 20hz to 20khz 0.08 thd and puts out about 25-30 volts max with full signal (testing with multimeter), so thats 20 volts x 4 amps = 80 watts but if the speaker required more current ( impedance drop ) wouldn't the amp transistor max out or does it still try to increase the current?.

Summing it up i think my question is when impedance drops is it wanting more power (watts) or is it after just current ( more amps ) because if it was just power it wouldn't make sense to me because why could it not take its required power from 8ohms, with speakers that are 100db @ 1 watt @ 8ohm they don't really need a lot more watts at 4ohms because it would only be 2 watts @ 100db for 4ohm so its a little confusing for me. Im just saying it has to be something else other than just watts.


This by far has been the best read about impedance and speakers etc
http://www.transcendentsound.com/Transcendent/Amplifier_Output_Impedance.html

[STEvil]

Impedance change is not important other than it is a mechanical function of the interaction of the coil and the magnetic gap. No, neither voltage nor current are constant. They change with amplitude, frequency, and the flux density of the coil and magnetic gap (most often known as impedance rise/droop).

Impedance change has nothing to do with the driver "wanting" more power, it is just change that happens due to movement of the coil.

As to why main power amplifiers do not operate at a higher voltage with less amperage, I couldnt really tell you, but I suspect it has to do mostly with the mosfets and other various electronics in the amplifier not being made for that, and that a high voltage being put into a speaker coil could produce a tesla-coil like effect possibly..?


On a note about amplifier failure, it is usually clipping (either input our output stage) that cause them to fail. A proper power-cycle for a mosfet is a gentle "hill" sine wave. A clipped signal looks like square hills and is effectively twice the RMS power (and thus twice the heat to dump from the mosfet and the coil). When the mosfet gets hot enough it enters a cascade which basically means the circuit inside of it overheats and melts. The effect is somewhat like what you would see if you have ever done arc welding and is correctly called "electromigration" (Pentium 4's did that..) although in a bit more of a spectacularly explosive and flaming style ;)

[[DANGERDAN]]

Impedance change has nothing to do with the driver "wanting" more power, it is just change that happens due to movement of the coil.

This is what im interested in, thanks for that i think im soo close xD, i will get back on what stevie said.

[Nanometer]

The only thing a preamp can do is boost the voltage, peak to peak. Say you have a 10 volt p2p frequency source and it is supplied to a an amplifier. The resulting power is 125 watts for an 8 ohm speaker. The voltage out of the preamp is the same voltage out of the power amplifier. What has changed is the available amperage in the system. As I said before the current is very low coming from a preamp, after the signal gets to the amplifier the capability to have a lot of power is available. I do think it is misleading to say that it has more current after the amplifier. While that is true, it is only true while the system is doing work and actually utilizing it. Once again, the amplifier provides a current draw and does not alter the voltage.

When the speaker is at its resonant frequency, the resistance is at its highest. This is a good thing as well because a resonant frequency while it can give off a lot of power, it will simultaneously lower the feed power by the higher resistance. And luckily the same effect happens again when the speaker reaches higher frequencies. High frequencies do not need the same amount of power that lower frequencies do. Thus the higher resistance helps to balance out speaker's output and SPL at higher frequencies. Though not for one second would a single speaker provide a smooth curve through out all the frequencies. With today's technology it does not exist.


I really hope I answered something, I think I might be misunderstanding what you are trying to ask. :(

take a look at these

http://www.bcae1.com/hcvsnohc.htm

http://www.caraudiohelp.com/newsletter/speaker_impedance.htm

[[DANGERDAN]]

You certainly are helping, part of learning is discussing problems so i am very appreciative of your help.

Once again, the amplifier provides a current draw and does not alter the voltage.
From my testing with a multimeter when i test the voltage output of my preamp it averages about 1.5v (100% volume) and when it is sent to the main in and i test the terminals i get a different voltage roughly 25v average, indicating to me there's been a voltage increase and when my headphones are connected via HP jack from the amp there is the same voltage ( 25v ).

Can you explain this at all ? because to me it sounds like it is in fact amping the voltage and from why i read both voltage and amps need to be in phase with eachother to work properly.

[Nanometer]

I could be wrong with the constant voltage assumption. Though an explanation to a difference in voltage could be the Gain factor. Your audio jack is a 32 ohm jack I believe, a typical amp is 8 ohms.... I believe. What I'm guessing is that because of the analog source you are using has a high resistance, there needs to be a compensation to raise the voltage back up. It sounds like the gain is actually something other than one, and what your tests show that it is much higher, which I find pretty interesting because I had no idea of that fact. You are intriguing me to start testing my own equipment haha

Check this out, I read through it and it's a good read, it confirms everything you've tested so far.
http://www.installer.com/tech/preamp.html

[[DANGERDAN]]

Well i would have believed that the preamp was the sole source for volts but when i did the math it wasn't making sense so i had to do some practical to work it out.
But i am fairly certain amps have their own op amps to increase the voltage and they must because 2-4 volts is just not enough to output enough watts for eg.

marantz sr4320
80 watts 20hz-20khz
guess of 4 amps with math calculations from multimeter testing
24 volts average tested

Now if it was 4 volts it would look like this 4 x 4 = 8 watts clearly not enough so using the test result volts we have this 20 x 4 = 80 watts, now this looks good.
The higher the current the less volts is needed like a rotel 1080 which is 133 amps only needs 1.65 volts to reach its rate 200 watts, so in saying that maybe not all amps have voltage amplifiers if they are not needed.

With the link you showed me this is with cars and when discussing with my mate a couple weeks ago we both found out that hometheatre systems and car systems are built differently, car batteries can only output 12v so there is a limit for that and that's why you will see very low impedance car amps because they are high current to make up for the low voltage. The voltage gain nob on the car amps seem to be a voltage gain nob and the voltage power from the head unit probably is added with the power amp as well giving more volts on top of the power amp gain.
Car amps still need to be hooked up to the battery and don't rely on the head unit alone for its power.
Will come back with more.

[Nanometer]

Yea that's all true about car amplifiers. Everything you've said also makes sense to me, I'd be surprised if you had a question you weren't capable of answering, you clearly know more than me lol :)

That is correct, a car sound amplifier is limited to its 12 volt source and must compensate with a low resistance speaker to compensate.

[[DANGERDAN]]

Your guys help with the previous threads has helped me a lot but i do research a heck of a lot when im investigating something and i usually come to you guys when im stuck, it helps just talking about it in a thread i know plenty of times while writing a post il get a lightbulb moment.

Impedance change has nothing to do with the driver "wanting" more power, it is just change that happens due to movement of the coil.

Is this why car speakers can be configured for low impedance ?? because of the design of the excursion distance from the coil ??.

[STEvil]

Car audio amplifiers are built to power lower impedance drivers. Its mostly to combat impedance rise, and its popular to build large low impedance drivers. Nothing more special than that.

Nanometer - No, 12 volts input to a car audio amplifier does not limit it to low impedance drivers. The input stage of the amplifier increases "12" volts to 40-60+ volts.

[Nanometer]

without a transformer that isn't possible. Every amplifier is limited to the supply voltage. For the car case supply is 12 volts. I'd be very interested to see how that gain above the supply voltage was achieved.



http://www.bcae1.com/spkrimp.htm

Though brief, this explains it well.

[STEvil]

Here's a direct quote from "Boon" on another forum since he explains it better than I ever could imagine to ;)

For reference this was a discussion about amplifiers dieing and what causes it.


Okies - most amp power supplies are unregulated - they just make as much voltage as they can with a given input voltage.
They use a fixed multiplication transformer, say 10:1 - so you feed them 14.4v, they turn it into a square, then 10:1 it to get 144v rails. Or you feed it 12v, it gets turned into a square, you get 120v rails. Less rail voltage = less current across the load = less wattage = less power = less heat.

The duty cycle of the power supply is fixed, most of them run really dumb PWM controllers like TL474 which just makes a square wave of fixed duration and that's about it.

Some of the more cunning amps (JL, Soundigital) use an intelligent controller that will increase the duty cycle of the PWM on the power supply when the input voltage drops. These are the amps that you will pop from low voltage because in this case less voltage = more current = more voltage drop due to Rds(on) in the FET = more heat. But these very same intelligent controllers usually have some pretty badass protection circuits that will shut down the amp or limit the output before this is allowed to happen.

The rail voltage becomes important because say you are driving the amp with a 5v signal and you're asking for 12x gain for a 60v output. If the rail voltage sags because of input voltage drop and the amp can only deliver 45v at the output then obviously you get clipping.

When you get clipping 2 things happen - the output FETs are running continuously rather than pulsed (pulsed rating is usually ~70% more than continuous) and the inductive load from the woofer disappears since it's working as a DC resistor rather than a reactive AC load. So the resistance plummets and the output current spikes. Then you have a race between 4 things: the output FETs overheating and blowing up, the power FETs overheating and blowing up, and the over-current protection kicking in and stopping it. Thermal protect won't save you because it takes a long time for the entire heatsink to warm up and trip the thermister that provides thermal protection - this is extreme, localised heating. The last thing is the wave falling again, dropping the voltage hence the current hence the heat. The lower the frequency the longer the wave will stay clipped hence the more chance you'll pop the amp.

So, long story short - it's not voltage drop that kills amps. The whole 'less voltage means more current' thing is a myth, the amp just produces a voltage across a resistance and pulls as much current as it needs to cause that voltage drop. Basic ohms law blah blah.
What kills the amp, is the clipping generated when your voltage drops with too much gain. Likewise you can kill an amp if you clip the :banana::banana::banana::banana::banana: out of it with perfectly good voltage - in fact it'll die faster, because it's producing more rail voltage so there will be more current :)

People often see low voltage just before their amp dies - usually it's a massive current spike in their system that causes the voltage to drop - this spike is usually caused by either the clipping mentioned above, or the fact that their amp has already started to fail and the shorting-out components are presenting a near-zero resistance so the battery is dumping current.

edit

Just so you know, the torroids are the transformers.

Here's a picture for reference. This is a cheater though as this amplifier technically has only an input stage where most other amps have an input and output.

http://i216.photobucket.com/albums/cc232/STEviltoo/Amps/warhorse.jpg

[Nanometer]

awesome, thanks for the info!

[[DANGERDAN]]

Yea i came across that a few days ago when questioning power outlets from the wall.
Im just a little confused on your statement in said previous post and hope you can enlighten me more please xD.
"Impedance change has nothing to do with the driver "wanting" more power, it is just change that happens due to movement of the coil."
Ok so not more power is being required perhaps but is more current ? is it the case that more current is needed to control the woofer cone better because the reason for the impedance changing is due to the efficiency changing so it is obviously looking for something and can obviously cause more stress for the amplifier itself.
One other thing and this is quite a interesting theory that i wonder if you know of nano, At a certain power output can determine the lowest impedance for eg.
SR4320 as example again
80 watts
4 amps
20v ( 25 volts max )
Now if a speaker was to use all those watts just under the distorted level it would have 20v/4 amps = 5ohms minimum impedance ?? if my math is correct and trust me when i say my math is horrible (funny story i might tell one day) then if you say use a speaker that uses half of that power, 10/4 = 2.5ohms.
But... i know this is probably wrong again because the volts/amps are out of phase when doing that and the current and volts have to be in phase dont they ? and the 4 amps would be halved yet again ? but you understand the theory i was trying to conclude, basically is the impedance output dependent on the phase connection between volts/amps and not actually on the current amount ?
When the impedance dips half from say 8ohm to 4ohm what electrical components insure a proper power output of 2x like math states it should but obvs not all amps can and i assume its the amps that's needed, the more amps the better in can supply more power down a lower impedance ????

THANKS AGAIN LOVE YOU ALL LETS ROCK WITH THE KNOWLEDGE WE HAVE AND NEVER STOP REPLAYING.

[Nanometer]

One other thing and this is quite a interesting theory that i wonder if you know of nano, At a certain power output can determine the lowest impedance for eg.
SR4320 as example again
80 watts
4 amps
20v ( 25 volts max )

I see what youre saying, but I am not sure about how we could find it. The theory I see is that lower resistance is pulling more power. But because of the high efficiency at resonance, locating the lowest resistance would interfere with this. But you were asking about at what power output. In this case, I believe lower power output is more efficient. The more power you send to a speaker, the more goes to waste in vibration damping and heat absorption.

Now if a speaker was to use all those watts just under the distorted level it would have 20v/4 amps = 5ohms minimum impedance ?? if my math is correct and trust me when i say my math is horrible (funny story i might tell one day) then if you say use a speaker that uses half of that power, 10/4 = 2.5ohms.
But... i know this is probably wrong again because the volts/amps are out of phase when doing that and the current and volts have to be in phase dont they ?

I believe you are correct with that assumption. And they are off by a 90 degree phase shift.

and the 4 amps would be halved yet again ? but you understand the theory i was trying to conclude, basically is the impedance output dependent on the phase connection between volts/amps and not actually on the current amount ?

To my knowledge the out of phase characteristics cannot be altered because that is just the way of A/C. the 90 degree out of phase is permanent. The impedance is not related to the out of phase of current and A/C. The impedance is related to, frequency of the signal and power output(I believe).

When the impedance dips half from say 8ohm to 4ohm what electrical components insure a proper power output of 2x like math states it should but obvs not all amps can and i assume its the amps that's needed, the more amps the better in can supply more power down a lower impedance ????

Every time you half the resistance load, you double the power. This is just simply because the current is doubled; and of course assuming the same voltage feed source. The components that insure proper power output are the power amplifier, and assuming your speaker can handle the new load now that you halved the resistance. Without the proper amperage in the signal the signal would suffer and cause clipping of the frequency. Though I am not sure about that general last statement you made there. In general I do believe that to be true to an extent, but there may be another fundamental idea that we are leaving out.

Current lags the voltage, just looked it up. Google Inductor on Wikipedia and characteristics of A/C


Inductor from Wikipedia (http://en.wikipedia.org/wiki/Inductor)

[STEvil]

"When the impedance dips half from say 8ohm to 4ohm what electrical components insure a proper power output"

mosfets and capacitors.

[[DANGERDAN]]

Ok im pretty close i think,
Does impedance change with volume or is it just with frequency ?

[STEvil]

Just with coil movement in the magnetic gap, until you reach the point of power compression (the point where you add more power and gain no output).

[Geahwimbhem]

To each their own; Ill take any resolution I want, deeper colors, no stretchmode hassles, and crisper picture any day.
Also, sorry for the repeat, didnt notice Sobek has great taste as well.

[[DANGERDAN]]

Well its been a while since this thread was started and im back for more xD, I have spent the last couple of months ( tbh it feels like more ) researching about the physics of electricity and i stressed myself so much into this research that i think its fair to say its become of interest to me and i enjoy it.
I have learned quite a bit and learning about electricity alone has helped me to understand all about audio technology as the entire structure is built around it and inductors/electromagnets, i still have a fair journey ahead of me but i feel quite comfortable now and not hitting myself trying to understand it all at once xD.

Just to cap off this thread and what i was asking id like to come back to you with my version of the answer i was looking for and some other things on top.
I was looking for a answer with impedance and i must say that it surely is not a easy subject nor easy to understand, compared to DC resistance AC has a whole lot more involved with reactance, frequency, phase angle etc but i was able to get through it all and found what i was looking for... eventually.
The speaker works around a voice coil obviously and this component is a electromagnet design and this simple but complex part is built around the electricity and the physics for this explains exactly how it works to a certain point.
Impedance for a electromagnet and i only just recently caught on to this at a engagement party while talking to my cousin, is the magnetic field created from the electromagnet, the electromagnet when given a certain frequency/current reacts and creates a magnetic field which creates this force that attracts or repels metals or irons. Its this magnetic field that controls the impedance and the frequency supplied to the electromagnet changes the effect of this impedance, current gives off a magnetic field and voltage gives off a electric field. The number of wraps around a voice coil and the size of the wire gives off a different impedance and its this factor that gives speaker designers control over the current and how the electromagnet works, this is how car speakers can be made for such a low impedance compared to HT systems.

Any disagreement cause i have more questions :)

[STEvil]

Really they arent that much difference impedance wise. Field strength changes dramatically due to excursion so while at resting you may measure 4 ohms on the car audio driver and 8 ohms on the home audio, during movement they both may dip to 2 ohms or lower and raise to points higher than 20 ohms.

This is also why it is important how you wire multiple coils. When wired in parallel you have a stronger field generated than an equivalent one with coils wired in series.

Mr "HHR Ed" explains how this works very well in this video.. of random related note, Charlie probably knew this guy before he came to XS ;) : http://youtu.be/IFFDrWGUDkM

edit

I forgot to mention I replied to that video on another website with some info he missed. Here's the reply quoted below as it is also related ;)



Something you missed in the video was the direction of current flow and time delay. With series coils (depending on the winding) the current flows UP the coil then back DOWN causing the magnetic forces to fight each other slightly. Very slightly :p Again (and partly a causal factor of the coils "fighting" each other) with series the delay of energization the circuit will be greater.

[[DANGERDAN]]

So what your saying is that in a typical comparison the difference between home theater speakers and car speakers are at no real difference from each other in terms of impedance, if this is the case then would it be sufficient to say that you could safely crossmatch speakers between car amps and HT amps without a problem as long as the amp can handle the low or high value impedance the speaker presents.
It was my understanding that car speakers were made different in terms of impedance to fight off high impedance due to the limitation in voltage ( without a transformer ).



As to why main power amplifiers do not operate at a higher voltage with less amperage, I couldnt really tell you, but I suspect it has to do mostly with the mosfets and other various electronics in the amplifier not being made for that, and that a high voltage being put into a speaker coil could produce a tesla-coil like effect possibly..?

From what i found the ratio of the output of current and voltage determines the impedance output to a given wattage, high current + low voltage = low impedance, Low current + high voltage = high impedance. What i have found is that the phase angle between voltage and current is the same at a given impedance and volume adjustment will affect both identically, for eg if you increase the voltage to a given frequency that is creating a 8ohm load the voltage and current increase simultaneously within phase with each other, when the impedance drops the ratio changes with the current increasing and voltage staying the same (at a given wattage).
So could a given amplifier rated at 80 watts @ 8ohms MAX! be able to load 40 watts @ 4ohms due to it working out to be the same amount of current.
Though most of the manufactured amps iv seen still are quite high output voltage that would be mostly because its a lot easier and cheaper to build, unlike ones that are more high end with bigger transformers and larger heatsinks to support it. Is it fair to say that higher current amps are better suited for high end systems for better audio quality? as the nature of the delivery of power is more natural due to the phsyics of electromagnets only create magnetic fields with current and not voltage and that the given higher current also has higher damping control.



Impedance change has nothing to do with the driver "wanting" more power, it is just change that happens due to movement of the coil.

You are correct in this statement when saying that the impedance change from a voice coil is not due to it wanting more power but from the physical reaction from the magnetic field, but does the diaphragm or any other element affect the impedance like for example when you see the high impedance spikes on a graph they are from the speakers resonance and or ported enclosure. It would seem to me that this resonance states that infact the force behind trying to reproduce certain frequency has a major affect on the overall impedance in the end am i wrong ??

[STEvil]

There is a difference between a 4 ohm nominal and 8 ohm nominal load of course, but enclosure style and system tuning will play a huge role in final impedance curves. So you could technically say yes. There are also transformers in car audio amps.

Yes, more dampening is desirable.

My understanding is that the spikes are from complementary waves. If you look up quarter wave theory you should get a fairly clear understanding of how they work. Enclosure modes (resonant frequencies) and driver diaphragm resonance will both influence impedance spikes but only if they were not built strong enough for the job in the first place. They move too little if built correctly to influence output meaningfully. As to frequency reproduction inducing impedance change, this is what an "impedance curve" is for when you build and model your enclosures. Impedance and excursion curves go hand in hand when making sure your enclosure and drivers are suitable for what you want to use them for.

[[DANGERDAN]]

Agreed, i think i have learned all i can at this point and would need to go into deeper mathmatic context with physics if i want to learn more, i thank you all cause now i feel satisfied woo!.

For those that need something that has everything and anything about physics for electricity the following link seems to have the most indepth and helpful information about it all.

http://www.allaboutcircuits.com/