# A new way to look at amplifier power??



## Fellippe (Sep 15, 2006)

The "watt isn't a watt" argument has been controversial, and I don't intend to start a war on this issue, but here's a conversation between an EE guru friend of mine (who is way stronger than myself in this area) with an interesting theory...

enjoy:
_______________________________________________

You know, CG, I was having the convo with Vu, and it seems like there is a "torque" factor involved with amps that is simply not quoted. As an EE it's hard to rectify POWER that is unquantifiable....very disturbing! 

I equate HP to watts...we all get 200 hp, 400 hp, 530 hp (Alpine Diablo!)....but what about torque?

These Phoenix Gold MS amps I have now have a lot of torque....more effortless power. Every amp will give you power when you crank, but how many have it down low off idle? 

I think as cheesy as the car analogy is, it might be going somewhere in the right direction...

All of the home setups I've heard so far have been, 2 , 5, 10 watts...maybe a 20 watter. 

I still don't get it, lol. 

His response:
______________________________
I'm not sure this analogy is as far off as you think. I'm just spitballing here, but it makes sense.

Recall that Power = Current x Voltage. So to make 100 watts, you can either create 1 amp at 100 volts, or 1 volt at 100 amps or anything in between.

However, the nature of cone/dome type speakers is that current through a voice coil creates a magnetic field, which interacts with the driver's permanent magnet to propel or retract the voice coil/cone assembly. But that force is based on current through the coil - not voltage across the coil.

Therefore, an amp which creates power by producing high current has better control over conventional loudspeakers than an amp which produces high voltage but low current. So in this case, as you hypothesized, current would be analogous to torque where voltage might be analogous to HP. And just as engine RPM relates the two under the hood, the impedance of the speaker relates the two inside the amplifier.

It would be interesting to take one of your Phoenix Gold amps and a similarly powered cheapy amp and do a test which is the equivalent of a torque curve for a motor - maybe plot the output current versus input voltage and the output voltage versus input voltage and see how the area under the curves differ for the two amps...

Interesting...

-- cg


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## SQ_Bronco (Jul 31, 2005)

Fellippe said:


> But that force is based on current through the coil - not voltage across the coil.


if the resistance of the voice coil is not variable (or a function of voltage), current and voltage are going to be coupled. V = I*R. The only way to increase current is to increase the voltage.


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## Kenny Bania (Aug 1, 2007)

Fellippe said:


> It would be interesting to take one of your Phoenix Gold amps and a similarly powered cheapy amp and do a test which is the equivalent of a torque curve for a motor - maybe plot the output current versus input voltage and the output voltage versus input voltage and see how the area under the curves differ for the two amps...


That would be a great way to test the hypothesis and should be pretty easy to do with a standard DMM, right?


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## Guest (Aug 28, 2007)

SQ_Bronco said:


> if the resistance of the voice coil is not variable (or a function of voltage), current and voltage are going to be coupled. V = I*R. The only way to increase current is to increase the voltage.


agreed. The analogy is fatally flawed.

Once you specify load impedance, you no longer have the "freedom" to say ... "I can get 100 watts with 1 volt and 100 amps, or 100 volts and 1 amp."

Amplifiers are NOT rated at 100 watts (for example) ... they are rated at 100 watts _into 4 ohms_. This completely determines BOTH voltage AND current ... leaving no room for such a "torque analogy".

At the risk of beating it to death ... amplifier A can NOT deliver 100 watts into 4 ohms at a different voltage OR current level than amplifier B.


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## MarkZ (Dec 5, 2005)

Fellippe said:


> The "watt isn't a watt" argument has been controversial, and I don't intend to start a war on this issue, but here's a conversation between an EE guru friend of mine (who is way stronger than myself in this area) with an interesting theory...
> 
> enjoy:
> _______________________________________________
> ...


He's right that it's the current through the speaker that dictates displacement (among other things). However, it doesn't make much sense to rate amplifiers based on current since they are actually voltage amplifiers. That is, they take an input voltage and (ideally) produce a signal that's exactly N times the voltage amplitude of the input. The value of N depends entirely on the gain setting of the amp. They're typically called "power amplifiers" because the secondary task that the amp serves is to drive low impedance loads (ie. supply lots more current than the preamp device can).

*If you hook up a different impedance load you're NOT going to be changing your value of N*. This is important because if you obtain V-I curves like he suggests, you're going to get a flat line _until_ you overdrive the amp (ie. drive it into clipping). If instead he means to try to capture the maximum voltage swing as a function of load, then that's something that can often be surmised based on the power figures that manufacturers provide. Although sometimes they don't give us the whole story, so a lot of guesswork is involved.

But yeah, I'd like to see all manufacturers give us useful ratings, probably in the form of power output or "voltage swing" as a function of load impedance.

PS - This is what a basic spec sheet should look like: http://www.zedaudio.com/Products/Minilith-Spec.htm

Very simple, very informative. Look at the first set of ratings:



zed said:


> Output Voltage (volts into 1 ohm) 24.5
> Output Voltage (volts into 2 ohm) 28.3
> Output Voltage (volts into 4 ohms) 28.3
> Output Current (amps into 1 ohm) 24.5
> ...


Notice that the output voltage rating gives you the output current rating that your friend wants. (eg. 28.3v / 2 ohms = 14.15a)


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## mach_y (Sep 8, 2006)

and there is such a thing as a current amplifier, albeit quite rare... one such example, by a genius IMO, Nelson Pass:

http://www.firstwatt.com/products/f1.htm


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## Fellippe (Sep 15, 2006)

werewolf said:


> agreed. The analogy is fatally flawed.
> 
> Once you specify load impedance, you no longer have the "freedom" to say ... "I can get 100 watts with 1 volt and 100 amps, or 100 volts and 1 amp."
> 
> ...


So how do we explain the torque analogy?

If it's not watts/volts/amps, it has to be something...no?


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## aneonrider (Apr 28, 2007)

It is P= E^2 / Z

Not simply P=IE, since in a speaker, impedance changes with frequency.


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## MarkZ (Dec 5, 2005)

mach_y said:


> and there is such a thing as a current amplifier, albeit quite rare... one such example, by a genius IMO, Nelson Pass:
> 
> http://www.firstwatt.com/products/f1.htm


Good point. But that's not something I'd want to use unless the speaker system was designed specifically for it.


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## Guest (Aug 28, 2007)

mach_y said:


> and there is such a thing as a current amplifier, albeit quite rare... one such example, by a genius IMO, Nelson Pass:
> 
> http://www.firstwatt.com/products/f1.htm


hee hee ... notice the recommendation for full-range drivers  this amp won't play well with typical crossover networks  

And remember, from simple application of Ohm's law : Any speaker with a reactive impedance can't possibly generate a frequency-flat acoustic output with _both_ a frequency-flat voltage drive _and_ a frequency-flat current drive. Guess which way most loudspeakers are designed?

This, of course, reinforces Mark's point about "special" loudspeakers for high-output-impedance amps.


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## Luke352 (Jul 24, 2006)

Would this be a bit like the Audison Thesis, which hasa high current mode 2 x 100, and a high voltage mode 2 x 200 or something like that?


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## Oliver (Jun 25, 2007)

Luke352 said:


> Would this be a bit like the Audison Thesis, which hasa high current mode 2 x 100, and a high voltage mode 2 x 200 or something like that?


This one? http://ampguts.realmofexcursion.com/Audison_HV_Sedici_THK/


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## 89grand (Nov 23, 2006)

Luke352 said:


> Would this be a bit like the Audison Thesis, which hasa high current mode 2 x 100, and a high voltage mode 2 x 200 or something like that?


I would bet that like most amps that use this terminology, they are refering to high current/high voltage as the ability to drive low impedances in high current mode and driving normal impedances (2 ohms or greater) in high voltage mode. 

In other words specs are probably something like:

High Voltage mode:
100 watts x 2 @ 4 ohms
200 watts x 2 @ 2 ohms

High Current mode:
50 watts x 2 @ 4 ohms
100 watts x 2 @ 2 ohms
200 watts x 2 @ 1 ohm

I'm not saying these are the exact specs, but similar in ratio. So, with these amps, you don't get any more power in either mode, it's just in what impedances it delivers it.


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## Luke352 (Jul 24, 2006)

Hic said:


> This one? http://ampguts.realmofexcursion.com/Audison_HV_Sedici_THK/


No this one sorry http://ampguts.realmofexcursion.com/Audison_HV_Venti/ I might have confused the names.

No it's not rated like that 89grand....


Here is it's rating 

High Current (13.8V - 1% THD):
2 x 200W @ 4 ohms
2 x 400W @ 2 ohms
2 x 650W @ 1 ohm
1 x 800W @ 4 ohms bridged
1 x 1300W @ 2 ohms bridged
High Power (13.8V - 1% THD):
2 x 400W @ 4 ohms
2 x 800W @ 2 ohms
1 x 1600W @ 4 ohms bridged
Fuse: 100A
Weight: 33lb (15kg)
Manufactured in 2004
Dual mono amplifier, dual BIAS, configurable A class percentage


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## SQ_Bronco (Jul 31, 2005)

Luke352 said:


> No it's not rated like that 89grand....


multiply his numbers by 4 and it's (almost) exactly what he said


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## Hillbilly SQ (Jan 26, 2007)

one thing i've proven is the memphis mclass fullrange amps are wonderful for mids and highs but struggle to get a sub moving. but sometimes you don't want torque on mids and highs. my xenon amps have torque out the yingyang. fullrange mclass=gentle touch.


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## dejo (Jan 3, 2006)

It seems to me that back in the day that the fosgate power 1000 had 7.5 amp fuses inline as speaker protection. at this same point in time a good friend had a hifonics boltar that would blow 30 amp fuses inline. now how does this fit into the equation of a watt is a watt.


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## durwood (Mar 7, 2007)

dejo said:


> It seems to me that back in the day that the fosgate power 1000 had 7.5 amp fuses inline as speaker protection. at this same point in time a good friend had a hifonics boltar that would blow 30 amp fuses inline. now how does this fit into the equation of a watt is a watt.


because the fosgate had fusing on EACH of the outputs and the hifonics had fusing on the main power line-and since class a/b amps are at most 60% efficient, the fusing does not need to be as large on the outputs as on the input.


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## 89grand (Nov 23, 2006)

dejo said:


> It seems to me that back in the day that the fosgate power 1000 had 7.5 amp fuses inline as speaker protection. at this same point in time a good friend had a hifonics boltar that would blow 30 amp fuses inline. now how does this fit into the equation of a watt is a watt.


I don't think is has anything to do with it really. In the case of the Fosgate, there really isn't any need for fuses on the speaker leads if the amp is good, which I guess they were. With the Hifonics, a 30 amp fuse on the power lead sounds sort of small for it, but all that means is that it was drawing more than 30 amps long enough to blow the fuse.

The fuses on these two amps were in two totally different sections of the amps so there really isn't much to gather from this in my opinion.


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## Oliver (Jun 25, 2007)

What is the benefit of the different designs?

High Voltage = pros , cons

Hich Current = pros , cons


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## Guest (Aug 29, 2007)

Hic said:


> What is the benefit of the different designs?
> 
> High Voltage = pros , cons
> 
> Hich Current = pros , cons


if you are driving a certain power into 8 ohms, you'll need "high voltage"
if you are driving that same certain power into 2 ohms, you'll need "high current" (relatively speaking).

You can't "choose" to supply a certain power into x ohms by giving those x ohms _high current_ one day, and maybe _high voltage_ the next day ...

to appreciate how 99.9% of all audio power amps work, we must first understand Ohm's Law, and the simple voltage source 

this thread is giving me a headache ...


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## MarkZ (Dec 5, 2005)

89grand said:


> I don't think is has anything to do with it really. In the case of the Fosgate, there really isn't any need for fuses on the speaker leads if the amp is good, which I guess they were. With the Hifonics, a 30 amp fuse on the power lead sounds sort of small for it, but all that means is that it was drawing more than 30 amps long enough to blow the fuse.
> 
> The fuses on these two amps were in two totally different sections of the amps so there really isn't much to gather from this in my opinion.


Fuses on the outputs are a great feature. When I'm dictator, car amps will have at least 3 fuses in them. One for the main line, and two on the rails. I'd also consider two more on the outputs.


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## Fellippe (Sep 15, 2006)

werewolf said:


> if you are driving a certain power into 8 ohms, you'll need "high voltage"
> if you are driving that same certain power into 2 ohms, you'll need "high current" (relatively speaking).
> 
> You can't "choose" to supply a certain power into x ohms by giving those x ohms _high current_ one day, and maybe _high voltage_ the next day ...
> ...


Well, if it really just is plain ole I=V/R, then sure, I feel ya wolfie...(even though I doubt very much that in the real world, it THIS SIMPLE)....

BUT...

Explain to me why these older high current amps have so much balls compared to a lot of these newer amps? 

My MS1000 is rated 340 x 4 at 14 volts and just with two channels has more violence to the subs than a dedicated JL 1000/1, and for the front stage, more midbass, warmth, clarity, and music across the windshield than a biamped Alpine V12 and JL 300/4?

When you total up all the "watts", it's about the same.

But the listening experience is far from that. 

We'll just have to find a new way to define torque if it's not current then.


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## 89grand (Nov 23, 2006)

MarkZ said:


> Fuses on the outputs are a great feature. When I'm dictator, car amps will have at least 3 fuses in them. One for the main line, and two on the rails. I'd also consider two more on the outputs.


I'm curious as to what good fuses on the speaker outputs do. 

Not doubting it so much as I just don't get the need. If the amp fails, maybe, but if all is working as it should, what would be the benefit?

If fuses are great on the speaker outputs, can't anybody just add their own?


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## ca90ss (Jul 2, 2005)

MarkZ said:


> Fuses on the outputs are a great feature. When I'm dictator, car amps will have at least 3 fuses in them. One for the main line, and two on the rails. I'd also consider two more on the outputs.


Gotta love the old Soundstream amps


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## MarkZ (Dec 5, 2005)

89grand said:


> I'm curious as to what good fuses on the speaker outputs do.
> 
> Not doubting it so much as I just don't get the need. If the amp fails, maybe, but if all is working as it should, what would be the benefit?
> 
> If fuses are great on the speaker outputs, can't anybody just add their own?


Sure can, and that can be a good idea too.

Fuses on the outputs can not only protect the speaker, but also potentially save the output devices from destruction in multichannel configurations. Also, if you don't put fuses on the rails, then it might also serve in that capacity, especially if we're talking about a case where a BJT output device fails to a short. Although I'd have to think about that one...


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## tard (Jul 13, 2006)

Fellippe said:


> Well, if it really just is plain ole I=V/R, then sure, I feel ya wolfie...(even though I doubt very much that in the real world, it THIS SIMPLE)....
> 
> BUT...
> 
> ...



i think it's dampening factor you're describing?

here's my 1 penny on "louder". forget the factor of volume displacement. that is a part, but not the whole, and not relevant to what i'm saying. how rapidly you can change direction of the cone (transient response) and create a larger wave pressure differential, the louder it will be. the reasoning is energy/time. (all other factors the same) the same energy and less time will be louder. so the amp that has better control over the cone will produce "louder". 

2 amps rated the same power into a resistor, is a whole different ball game than what happens driving the reactive load and the dynamics of a speaker at work. especially these large inductive coils of todays monster subs.

i know some people don't like john yi and the raw engineering depths of this is going over my ability. but his explanation makes sense to me. their amps that make 1k have 2k of power supplies. one of the benefits of that is having the oomph to fight inductance and control that cone better. an analogy he gave was like putting 5 people in a honda.... the engine is going to feel it and the car won't perform as well as you'd like. and so does an amp when you tack on 4 subs or multiple large inductive coils. but with the beefier power section in other amps... they're still performing top notch.

maybe werewolf will turn me upside down on all of that. but that's the best i can explain it in different terms of why different amps will be less/more driving a speaker in the real world vs when they rate the same power on a resistor, on bench, in their lab.


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## ca90ss (Jul 2, 2005)

tard said:


> i know some people don't like john yi



Some??? You mean there are people who don't hate him?


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## durwood (Mar 7, 2007)

Fellippe said:


> Explain to me why these older high current amps have so much balls compared to a lot of these newer amps?


Most "high current" amps are a marketing dept's fancy talk. It's just like wolfie has said, it merely relates to your impedance load on the output. For example, soundstreams had a switch to switch the amp to allow lower impedance loads to be used, all it did was reconfigure the power supply to deal with the lower impedance load by lowering the rail voltage so that you don't kill the output transistors-you could never run it high current and high voltage at the same time because of ohm's law. There is nothing magical in the basics of electronics.



> My MS1000 is rated 340 x 4 at 14 volts and just with two channels has more violence to the subs than a dedicated JL 1000/1, and for the front stage, more midbass, warmth, clarity, and music across the windshield than a biamped Alpine V12 and JL 300/4?
> 
> When you total up all the "watts", it's about the same.


You are comparing more power against less power? Doh! *Slaps forehead and walks away.



werewolf said:


> if you are driving a certain power into 8 ohms, you'll need "high voltage"
> if you are driving that same certain power into 2 ohms, you'll need "high current" (relatively speaking).
> 
> You can't "choose" to supply a certain power into x ohms by giving those x ohms _high current_ one day, and maybe _high voltage_ the next day ...
> ...


Me too


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## Fellippe (Sep 15, 2006)

durwood said:


> You are comparing more power against less power? Doh! *Slaps forehead and walks away.
> 
> 
> QUOTE]
> ...


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## durwood (Mar 7, 2007)

Fellippe said:


> durwood said:
> 
> 
> > You are comparing more power against less power? Doh! *Slaps forehead and walks away.
> ...


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## Oliver (Jun 25, 2007)

werewolf said:


> if you are driving a certain power into 8 ohms, you'll need "high voltage"
> if you are driving that same certain power into 2 ohms, you'll need "high current" (relatively speaking).
> 
> You can't "choose" to supply a certain power into x ohms by giving those x ohms _high current_ one day, and maybe _high voltage_ the next day ...
> ...


I apologize for the headache!
So, high voltage amps and 8 ohm drivers = DIYMA
 [ not really ]

I am glad you are here as an undisputable voice of reason, Werewolf  

It's not enough to just know the answers, someone who is accomplished, acknowledged and respected, has to state the obvious


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## Guest (Aug 29, 2007)

thanks for the compliments, but we all gotta walk before we can run 

So listen, seriously, before we start dreaming up theories about the inadequacy of our abilities to measure a power amplifier  we must first demonstrate a command of the voltage source, as it drives a resistive load. Fair enough?

Yes ... the amplifier is not a perfect voltage source, because it has a tiny, but non-zero output impedance. But before we consider that effect (primarily in relation to _damping_), we must first demonstrate a mastery of the ideal voltage source it's emulating. Fair enough?

Yes ... a loudspeaker is a reactive, rather than purely resistive, load. But before we can hope to understand the complexities of a reactive load, we must first demonstrate a mastery of the simpler resistive load. Fair enough?

One cannot hope to suggest that Newton's Laws of motion are _inadequate_ at explaining a physical phenomenon, unless one can demonstrate a complete _mastery_ of said laws. Fair enough?

So ... let's say I've got a voltage source that applies 8 volts rms to a 4 ohm resistor.

- What's the rms current that will flow through the resistor?
- What's the average power dissipated by the resistor? Please show three (3) calculations to support your answer.
- Let's say someone suggests that he's got a different "kind" of source that will deliver the _same_ power to that resistor, but at a "higher current". What should we say to that person, and why?


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## MarkZ (Dec 5, 2005)

werewolf said:


> - Let's say someone suggests that he's got a different "kind" of amplifier that will deliver the _same_ power to that resistor, but at a "higher current". What should we say to that person, and why?


"Yo mama."


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## aneonrider (Apr 28, 2007)

werewolf said:


> - What's the rms current that will flow through the resistor?
> - What's the average power dissipated by the resistor? Please show three (3) calculations to support your answer.
> - Let's say someone suggests that he's got a different "kind" of source that will deliver the _same_ power to that resistor, but at a "higher current". What should we say to that person, and why?


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## Xander (Mar 20, 2007)

werewolf said:


> So ... let's say I've got a voltage source that applies 8 volts rms to a 4 ohm resistor.
> 
> - What's the rms current that will flow through the resistor?
> - What's the average power dissipated by the resistor? Please show three (3) calculations to support your answer.
> - Let's say someone suggests that he's got a different "kind" of source that will deliver the _same_ power to that resistor, but at a "higher current". What should we say to that person, and why?


Yay, homework!

1) 8 volts / 4 ohms = 2 amps

2) P=VI -> 8 volts * 2 amps = 16 watts
P=(I^2)*R -> (2 amps^2)*4 ohms = 16 watts
P=V*(V/R) -> 8 volts*(8 volts/4 ohms) = 16 watts

Not sure if you were just looking for equation manipulation, but that's all I can think of right now, haha.

3) We should say...now show me cold fusion! Because of these equations:

V=IR
P=VI

As far as the second equation goes, if you want to keep P the same and raise I, you need to lower voltage. But look at the first equation. It is mathematically impossible to raise I and lower V because V and I are on opposite sides of the equation, and the third value is a constant. If one goes up, so must the other, at the same ratio.


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## durwood (Mar 7, 2007)

I'll help this along because I'm bored...



werewolf said:


> - What's the rms current that will flow through the resistor?


I=8Vrms/4 ohms = 2Arms



> - What's the average power dissipated by the resistor? Please show three (3) calculations to support your answer.


P=V*I=8Vrms*2Arms=16Wrms
P=V^2/R=8Vrms*8Vrms/4ohms=16Wrms
P=I^2*R=2Arms*2Arms*4ohms=16Wrms

  



> - Let's say someone suggests that he's got a different "kind" of source that will deliver the _same_ power to that resistor, but at a "higher current". What should we say to that person, and why?


I'd refere them to here

http://www.diymobileaudio.com/forum/showthread.php?t=18564

or 

http://www.diymobileaudio.com/forum/showthread.php?t=18003&highlight=god


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## Guest (Aug 29, 2007)

Xander said:


> Yay, homework!
> 
> 1) 8 volts / 4 ohms = 2 amps
> 
> ...


thank you


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## Guest (Aug 29, 2007)

durwood said:


> I'll help this along because I'm bored...
> 
> 
> I=8Vrms/4 ohms = 2Arms
> ...


and thank you ... but lose the "watts rms" ... there's no such thing (that makes any physical sense). RMS values of voltages and currents DO, however, make sense ... but they are used to calculate AVERAGE (not RMS) power 

But now wait a second ... this other "source" i'm talking about, that will deliver 16 watts to the resistor at a "higher current" ... will do it with more balls! I mean, it's got a higher fuse rating on it and everything! You can show me all the equations you want to, but none of that fancy math stuff changes what i know!!   

sorry, i couldn't resist


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## durwood (Mar 7, 2007)

werewolf said:


> and thank you ... but lose the "watts rms" ... there's no such thing (that makes any physical sense).


Doh! Yes I know what you mean :blush:


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## chad (Jun 30, 2005)

Well, since we are looking at a new way to look at amplifier power, lets look at this. In the pro audio world we are finding amplifiers rated at 5KW+ that draw power from a 20A 120V outlet.... lets do the math here? Have we invented and energy machine? No. We have started rating amplifiers in regards as to what they will do with music. These amps mostly have SMPS inside and PWM or better yet as with Lab Gruppen a PWM secondary supply tracking the audio waveform and a class B final stage eliminating the need for crazy output filtering. A watt is a measure of energy, storing energy in a cap and recharging said cap THOUSANDS of times per second allow the amplifier to produce incredible power during transients but reproduction of a sine wave at full power will cause the amp to thermal out or protect itself in a short period of time. Is this cheating? I used to think so but now I don't... because I don't listen to tones.

Yes a very linear old-skool amp will run all day long into a dummy load while clipping like crazy, you have a glorified heater... literally if you saw my load-zilla. But what good does that do for the audio industry? Not a damn thing. Pro amps in their earliest forms (in the SS world) were simply laboratory gradient amps, often times driving shaker tables, coils, etc. in fact the Crown MA10K was originally designed to drive coils in MRI machines, waddya think of that minivanman? If you have 3 phase ability the MA10K for that application is much cheaper used in surplus than an audio intended MA10K (in case you wanted 2 amplifiers 10KW a piece that could make that power all day long).

The new ratings take a bit of getting used to but I have found that in the real world they hold true and work well. We MAY see this trend starting in car audio, you may start seeing higher numbers in power ratings, much higher. But for music, they speak the truth... and probably won't be rated "WRMS" 

http://www.labgruppen.com/media/C_TB_classTD_SMPS_intercooler_v2.pdf

http://www.labgruppen.com/media/Testing_Procedure_v1.pdf

http://www.labgruppen.com/media/C_TB_design_power_amps_v2(1).pdf

Chad


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## Guest (Aug 29, 2007)

Now, let's consider a reactive load. The are a couple of concerns with reactive loads ... for example, amplifier instability (due to possible phase shift in a feedback loop, is one way to look at it), excessive thermal stress on the amp (capacitive loads have a nasty way of demanding their _highest_ current when the voltage across them is _smallest_, meaning when the voltage across the amp's output stage is _highest_). But for now, to keep things simple (but accurate enough to discuss the issue), let's just say that a reactive load has a "resistance" that _changes_ at different frequencies (that's not accurate ... but it's close enough for the sake of this discussion).

If we use our friendly voltage-source-like amplifier to drive this reactive load, the consequence is simple : the current demanded by the load, from the voltage source, will change with frequency, in order to maintain the voltage supplied by the amp. Simple, right? Maybe our 4 ohm resistor looks like 4 ohms at 200 Hz, but looks like 2 ohms at 1kHz. What fundamentally changes about our analysis?

The answer is : nothing. The voltage source (amplifier) _supplies_ the voltage to the load. The load, in return, _demands_ a current from the source ... whatever current is needed, by Ohm's Law, to maintain the voltage. The load is not "free" to arbitrarily "demand" any current at all ... the current demanded will be dictated by its impedance, and its impedance alone. Likewise, the voltage source is not "free" to supply any current at all to the load ... it's fixed by Ohm's Law.

Now where you _can_ get into trouble is, if the impedance of the load drops low enough that the amp just can't supply the current demanded by that impedance at the driven voltage level ... maybe because of thermal stress, current limiting in the power supply or output stage, etc. So an amplifier _capable_ of delivering a higher current to a lower impedance load won't "quit" as soon as a lower-current-capable amp, as impedance levels drop. *BUT ... and this is the important part ... as long as you are not dipping below the "current reserves" of any amp in question (or otherwise introducing some electrical or thermal instability), all amplifiers delivering the same voltage to any load, MUST be delivering the same current to that load ... whether it is resistive, or reactive.*

Make sense? Think of an amplifer as a pure voltage source, but one that can only supply 100 amps of current (for example), no more. That does NOT mean it's free to decide when it will supply those 100 amps. The current will be defined completely by Ohm's Law ... the voltage supplied to an impedance and the impedance value itself. The only difference being, if the current calculated by Ohm's Law is greater than 100 amps, the amplifier needs to shut down to protect itself.

And this is true, even if the load "looks" like a different impedance value at different frequencies.


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## Guest (Aug 29, 2007)

chad said:


> Well, since we are looking at a new way to look at amplifier power, lets look at this. In the pro audio world we are finding amplifiers rated at 5KW+ that draw power from a 20A 120V outlet.... lets do the math here? Have we invented and energy machine? No. We have started rating amplifiers in regards as to what they will do with music. These amps mostly have SMPS inside and PWM or better yet as with Lab Gruppen a PWM secondary supply tracking the audio waveform and a class B final stage eliminating the need for crazy output filtering. A watt is a measure of energy, storing energy in a cap and recharging said cap THOUSANDS of times per second allow the amplifier to produce incredible power during transients but reproduction of a sine wave at full power will cause the amp to thermal out or protect itself in a short period of time. Is this cheating? I used to think so but now I don't... because I don't listen to tones.
> 
> Yes a very linear old-skool amp will run all day long into a dummy load while clipping like crazy, you have a glorified heater... literally if you saw my load-zilla. But what good does that do for the audio industry? Not a damn thing. Pro amps in their earliest forms (in the SS world) were simply laboratory gradient amps, often times driving shaker tables, coils, etc. in fact the Crown MA10K was originally designed to drive coils in MRI machines, waddya think of that minivanman? If you have 3 phase ability the MA10K for that application is much cheaper used in surplus than an audio intended MA10K (in case you wanted 2 amplifiers 10KW a piece that could make that power all day long).
> 
> ...


strange ... i listen to tones ALL THE TIME. Fourier showed us that ALL complex signals are nothing but a linear combination of tones  And since superposition holds for linear systems (by definition), we have no choice but to listen to tones, in combination  

But I know what you mean ... i've got an amplifier right here with substantial energy reserves inside (aka a large bank of capacitors). And I know that when I REMOVE THE POWER SUPPLY altogether, by unplugging it, it STILL PLAYS for almost 30 seconds  In other words, it delivers energy to the load (i've chosen that wording very carefully) ... for 30 seconds ... while drawing exactly zero energy from the power supply. In other words ... it's got INFINITE MUSIC EFFICIENCY !!!!!

I'm a marketing genious


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## chad (Jun 30, 2005)

Very much so. Along those lines. Early PWM amps were plagued with failure in the output filtering especially driving reactive loads. The first paragraph sums up the reason perfectly. 

A poorly designed passive crossover with improper grometric inductor placement can reak havoc at higher power levels in the reactivity department but be perfectly fine at lower levels. This was the reason I made Thousands of dollars repairing Peavey DPC750's and 1000's from only one customer that had a ton of them and that one brand of speaker that got willy at higher power levels. They were overheating the filtering section on the ass end of the amp like it was nobody's busness. Until the crossover section in the speakers were looked at it was rather a mystery.



Chad


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## chad (Jun 30, 2005)

werewolf said:


> ... it's got INFINITE MUSIC EFFICIENCY !!!!!
> 
> I'm a marketing genious



Quick! It's time to change professions


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## Xander (Mar 20, 2007)

Thanks werewolf, I've really wanted to learn more about amps lately, and this is giving me a good solid base to learn upon.


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## Xander (Mar 20, 2007)

chad said:


> Very much so. Along those lines. Early PWM amps were plagued with failure in the output filtering especially driving reactive loads. The first paragraph sums up the reason perfectly.
> 
> A poorly designed passive crossover with improper grometric inductor placement can reak havoc at higher power levels in the reactivity department but be perfectly fine at lower levels. This was the reason I made Thousands of dollars repairing Peavey DPC750's and 1000's from only one customer that had a ton of them and that one brand of speaker that got willy at higher power levels. They were overheating the filtering section on the ass end of the amp like it was nobody's busness. Until the crossover section in the speakers were looked at it was rather a mystery.
> 
> ...


So was the crossover in the speaker presenting very low resistance to the amplifier at certain frequencies, or was it the actual driver that was the problem? If it was the crossover, how does that work?


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## Guest (Aug 29, 2007)

an interesting link about power ratings ... including the humorous "peak music power rating" from many moons ago :

http://www.1388.com/articles/tech_underAmp/

Every few years, some manufacturer introduces a "new" amp with lots of internal energy storage, and then lobbies for a new way to "specify" (in reality, nothing but a new way to "market") it's power rating. Why ... it just happened not long ago in the car audio biz 

But i digress ...


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## chad (Jun 30, 2005)

Xander said:


> So was the crossover in the speaker presenting very low resistance to the amplifier at certain frequencies, or was it the actual driver that was the problem? If it was the crossover, how does that work?


It was the crossover, the inductors were, well, inducing signal upon other inductors in, lets say for time savings sake, a strange phase angle. The more power the larger the magnetic feild getting over tot he other inductor. It's not ALWAYS good to overpower a speaker SYSTEM, crossovers not only have thermal power limits but physical too 

This was causing a very reactive load at higher power levles.


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## Xander (Mar 20, 2007)

chad said:


> It was the crossover, the inductors were, well, inducing signal upon other inductors in, lets say for time savings sake, a strange phase angle. The more power the larger the magnetic feild getting over tot he other inductor. It's not ALWAYS good to overpower a speaker SYSTEM, crossovers not only have thermal power limits but physical too
> 
> This was causing a very reactive load at higher power levles.


Okay, that makes perfect sense, thanks. When I eventually design and build some HT speakers with crossovers I'll be sure to get help on crossover design here first, haha.


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## durwood (Mar 7, 2007)

werewolf said:


> Every few years, some manufacturer introduces a "new" amp with lots of internal energy storage, and then lobbies for a new way to "specify" (in reality, nothing but a new way to "market") it's power rating. Why ... it just happened not long ago in the car audio biz


So who exactly lobbied for the CEA2006 compliant specs then? Inquiring minds want to know


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## mach_y (Sep 8, 2006)

durwood said:


> So who exactly lobbied for the CEA2006 compliant specs then? Inquiring minds want to know


my vote is Alpine... since they had their entire new product lineup CEA-2006 right from the get-go.


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## durwood (Mar 7, 2007)

I was thinking it was Rockford for some reason but Alpine was also in the back of my mind.


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## tard (Jul 13, 2006)

since we're on the topic of amps and power, i have a Q for wolfey.

a few years back i read a write up by Robert Zeff on a bench test he did. one amp was a Zapco 2kw, another was a us amps usa 2000x, and i forgot the third one.

power tests on a resistor, they were all fairly close in power, a little above 2kw. on a reactive load, zapco and the others power dropped, while the us amps cranked over 3kw.

what's your thoughts there? did dirk design in a rough power factor compensation? so when on the resistor the other amps V and A waves were in sync and the US amps was out of phase, then with the phase shift from the reactive load it brought the V and A waves closer to phase, where as the other amps suffered from the waves shifting out of phase?


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## Guest (Aug 29, 2007)

tard said:


> since we're on the topic of amps and power, i have a Q for wolfey.
> 
> a few years back i read a write up by Robert Zeff on a bench test he did. one amp was a Zapco 2kw, another was a us amps usa 2000x, and i forgot the third one.
> 
> ...


No ... the amplifier, emulating a volatge source, has no more control over the current _phase_ in relation to voltage, than it has over the current _magnitude_ in relation to voltage.

The amplifer supplies a voltage to the load. That voltage is simply a "gain factor" times the input (RCA-level) voltage. All aspects of the _current_ drawn from the amplifer are a function of the load impedance ... nothing more, nothing less. This includes the magnitude of the current, as well as the phase of the current.

An amplifer can no more _independently_ supply a voltage and current to a load, than I can _independently_ supply a force and acceleration to a fixed mass. Apply a net force to a mass, and the acceleration is determined. No more "degrees of freedom".

So why might one amp perform better? Different power levels, different distortion levels. I can have one amp, rated at 100 watts into a 4 ohm resistive load, that will only do so at 2% distortion. But another amp that will deliver the same power into a resistor at 0.5% distortion. One amp will test as more powerful, if my distortion limit for the test is 1%  And if each amp is asked to deliver a similar _voltage_ at a load impedance of 0.001 ohms ... they may react very differently indeed 

Not to pick on anyone in particular ... but this is why i always chuckle when someone suggests that a "new amplifier test" or "new amplifier specification" is needed. It's usually offered, and entertained, by those who don't even understand a simple voltage source and Ohm's Law.

I know that sounds nasty, but i can't help it


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## tard (Jul 13, 2006)

i can definately understand the situation with the distortion explanation. if i can find the article, i'll post a link. maybe you could evaluate it and see if there's something i overlooked in what was being said in it.


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## tard (Jul 13, 2006)

found it....... and found what i missed. they were simply driven to max output. distortion wasn't even looked at. just max, raw, the last drop of unclean nasty power they could squeeze out for SPL purposes.


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## chad (Jun 30, 2005)

werewolf said:


> Not to pick on anyone in particular ... but this is why i always chuckle when someone suggests that a "new amplifier test" or "new amplifier specification" is needed. It's usually offered, and entertained, by those who don't even understand a simple voltage source and Ohm's Law.
> 
> I know that sounds nasty, but i can't help it


I just feel that rating an amplifier at sine wave output is a bit unnecessary for a device designed to amplify music, not a high duty cycle tone. This article kind of sums it up, it's not directed at you but for others to paruse. I'm prettyy sure you know what I'm talking about.

http://www.crownaudio.com/pdf/amps/i-tech-livesound_jan07.pdf

Rail voltages at 200V and can be sustained for a few seconds max. But do they need to sustain any longer? That begs the question.


If you asked me about this 3 years ago I would have fought tooth and nail about the new rating system. I liked the "old iron amps." But after seeing the new breed of amplifier in action I can say that it really makes no difference, the new amps, say one that can make huge peak power but only sustain a fraction of that will SMOKE a similar amplifier that can sustain more then the newer ones. So yes a 5KW amp MAY be able to sustain 1KW but will chew an amp alive that can sustain 2KW when it comes down to the real deal. Pushing a bunch of 18's every time that kick drum hits.

It goes right along with the earlier thread of how much juice is REALLY getting pulled down those power leads to the boot.


Chad


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## Guest (Aug 29, 2007)

didn't mean to sound like a dyckhole 

Ohm's law works equally well with _complex_ impedances. Just replace the _real_ value "R" with a _complex_ number, and you've captured the way reactive loads work  What remains unchanged is this : a voltage souce delivers a voltage to a load (real or complex), the current (magnitude and phase, or if you prefer, real and imaginary) will be determined by the load impedance.

My plea is this : before anyone offers opinions or suggestions about the way amplifiers are currently specified or tested ... claiming various "inadequacies" in these areas ... please, PLEASE demonstrate a mastery of these specs and tests first?

Is that too arrogant or cold? I honestly don't think so. It's a very valuable part of the scientific method. Imagine preparing an article for a peer-reviewed, scientific journal ... where you claim to have uncovered a terrible flaw in Newton's F=ma (and i don't mean at relativistic speeds, or in huge gravitational fields). Don't you think a serious level of mastery, as well as EXHAUSTIVE tests where variables are rigidly controlled and observed, would be required in order to be taken seriously? I'm not dismissing the possibility altogether (as unbelievably unlikely as it would be), i'm just offereing some pre-requisites that would be necessary to withstand the strict rigors of logic and science.


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## Fellippe (Sep 15, 2006)

werewolf said:


> Not to pick on anyone in particular ... but this is why i always chuckle when someone suggests that a "new amplifier test" or "new amplifier specification" is needed. It's usually offered, and entertained, by those who don't even understand a simple voltage source and Ohm's Law.
> 
> I know that sounds nasty, but i can't help it


I couldn't get a degree in EE without knowing Ohm's law, Kirchoff's Current & Voltage Laws, Thevenin/Norton with dependent and independent sources, small/large signal analysis of BJTs, MOSFETS, etc. 

There's no confusion here, Werewolf. 

Where the confusion lies is hearing differences in similar rated amps, and seeing some amps with lower ratings outperform those with higher ratings. You choose to believe a watt is a watt (which is fine), and I after having these experiences begin to QUESTION whether that's true.

My problem here is that I propose a theory from someone who thought it out a bit, and all that anyone has been able to come up with is to wait around to find a way to use Ohm's law to disprove it???

Is real world resistance always fixed??? Is that first poster who suggested the resistance is the same automatically correct? (Are you automatically correct?)

The concepts of current and voltage take a good amount of time to truly "get". I=V/R is simple math, but understanding what current really is and what voltage ("potential difference") is takes time. Did anyone care to read or even challenge the thought that "current" controls speakers better than "voltage" does.....the only argument was to spin it that they'd always be equal, invalidating the hypothesis. 

Look Wolf, I'm not even claiming to be an EE know it all....just throwing out ideas that sound good on paper. On a daily basis I see the difference between using single phase 120/208, three phase 120/208, and three phase 277/480, and how the effects of going up in voltage are beneficial in reducing current. 

You're barking up the wrong tree if you think I don't "get" simple EE, and I'll go out on a limb and say that your mastery of EE concepts reeks a lil more Ph.D. than P.E.


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## Guest (Aug 29, 2007)

chad said:


> I just feel that rating an amplifier at sine wave output is a bit unnecessary for a device designed to amplify music, not a high duty cycle tone. This article kind of sums it up, it's not directed at you but for others to paruse. I'm prettyy sure you know what I'm talking about.
> 
> http://www.crownaudio.com/pdf/amps/i-tech-livesound_jan07.pdf
> 
> ...


I would seriously entertain a suggestion along these lines :

"We know that any complex signal can be decompossed into nothing but a linear combination of sine waves, aka tones. But a _single_ sinewave is not very representaive for two reasons :

1. Intermod distortion requires more than a single freqeuncy.
2. The crest factor (ratio of peak power to average power) of a single sinewave is not representative of music.

We recongize that amplifer design can "exploit" the crest factor of typical music, by storing sufficient amounts of internal energy. This may allow an amplifier to supply peak-bursts, for _short_ periods of time, even though the long-term _average_ power delivered is unaffected by internal energy storage.

Therefore we propose a test consisting of an industry-standard signal, somewhat more complex than a single sinewave, ...."

Know what i mean? First, demonstrate a mastery of simple engineerig concepts. Then, demonstrate why the new proposal is not just more marketing fluff, but real valubale stuff. Then, demonstrate that you're not just going to try to fool the consumer by inflating the results of the _existing_ tests, just to sell your product. Finally, propose the new method.

And yes, i know, my criticisms are kinda aimed wildly ... at manufacturers as well as hobbyists!


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## chad (Jun 30, 2005)

werewolf said:


> I would seriously entertain a suggestion along these lines :
> 
> "We know that any complex signal can be decompossed into nothing but a linear combination of sine waves, aka tones. But a single sinewave is not very representaive for two reasons :
> 
> ...



They have this industry standard signal in place, I'll find out what it is. Some folks chose to test with a more rigourous signal though, which, is fine with me.

I'm totally with you though 

*edit* Lab Gruppen's testing is a 1K tone 33.3ms on and 66.6ms off. But again, that's not the standard and this is for their max voltage bench "stress test" I'm pretty sure it's the same thing 20-20K for ratings testing. I need to gather more info before I can feel comfortable.


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## Guest (Aug 29, 2007)

Fair enough


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## SQ_Bronco (Jul 31, 2005)

tard said:


> i can definately understand the situation with the distortion explanation. if i can find the article, i'll post a link. maybe you could evaluate it and see if there's something i overlooked in what was being said in it.


http://www.caraudiomag.com/specialfeatures/0202cae_high_power_amp_test/

is this the article you are thinking about? There have been threads on a number of forums (including this one IIRC, definitely ECA) talking about the problems with the test methodology...


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## exmaxima1 (May 31, 2007)

89grand said:


> I'm curious as to what good fuses on the speaker outputs do.


One of the first things I learned out of school was that "transistors are the world's fastest fuses". It is doubtful that a fuse will blow fast enough to save an output stage. Plus, many transistors fail from exceeding their SOA (safe operating area) due to elevated temperatures. When the temps go up, the current ratings go WAY down. It would be near impossible for fuses to reliably protect against that.

Regarding the power advantage of a high-current amp versus a lesser design, keep in mind that the instantaneous DC resistance of a speaker can be much lower than its impedance---until the speaker starts moving and generates a back EMF (raising its impedance), the current can be very high. A high current amp design may very well perform better for transient response.

If you look at some woofers, such as Carver's massive subwoofers, the DC resistance is only a fraction of its AC impedance throughout its usable frequency range. Though the amplifier may be marketed as "2000 watts", that is predicated on a 4 ohm load while the actual working impedance may be more like 20-40 ohms over the subwoofer's range. The amplifier does not work so hard at those impedances.

Matthew


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## chad (Jun 30, 2005)

Fellippe said:


> Look Wolf, I'm not even claiming to be an EE know it all....just throwing out ideas that sound good on paper. On a daily basis I see the difference between using single phase 120/208, three phase 120/208, and three phase 277/480, and how the effects of going up in voltage are beneficial in reducing current.


I see where you are coming from but remember one thing, the amp switches voltage, the current delivered is derived from the loudspeaker impedance.... which does not change.

In your app you are raising the voltage, lowering the current but the "impedance" of the device also is raised to accomodate the higherr voltage present. If you took a 120V motor and ran it at 220V.... see what I mean.

In a lamp (because they are not bulbs) that is intended for 220V use has a thinner/ less resistive filament then one designed for 120V operation.

And yes, lamps intended for use overseas are not as durable as ours.


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## chad (Jun 30, 2005)

exmaxima1 said:


> One of the first things I learned out of school was that "transistors are the world's fastest fuses". It is doubtful that a fuse will blow fast enough to save an output stage. Plus, many transistors fail from exceeding their SOA (safe operating area) due to elevated temperatures. When the temps go up, the current ratings go WAY down. It would be near impossible for fuses to reliably protect against that.
> 
> Regarding the power advantage of a high-current amp versus a lesser design, keep in mind that the instantaneous DC resistance of a speaker can be much lower than its impedance---until the speaker starts moving and generates a back EMF (raising its impedance), the current can be very high. A high current amp design may very well perform better for transient response.
> 
> ...


Excellent post!

It's always a rough battle in the "to fuse or not to fuse" speakers, I am very much against it. One thing is for sure... you will either be blowing speakers or replacing fuses all the time and a fuse knows no impedance rise of the VC due to heating. Best bet is to scale the gear for the intended job so you don't have to fuse.

Also keep in mind (not you matt) that there was an amp pictured on here a bit back with what appeared to be speaker fuses. I'm pretty darn sure those are rail fuses, which, is not a bad idea when the "world's fastest fuse" fails to short to the rails 


World's fastest fuse, man, I haven't heard that one in a long time


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## Guest (Aug 29, 2007)

exmaxima1 said:


> One of the first things I learned out of school was that "transistors are the world's fastest fuses". It is doubtful that a fuse will blow fast enough to save an output stage. Plus, many transistors fail from exceeding their SOA (safe operating area) due to elevated temperatures. When the temps go up, the current ratings go WAY down. It would be near impossible for fuses to reliably protect against that.
> 
> Regarding the power advantage of a high-current amp versus a lesser design, keep in mind that the instantaneous DC resistance of a speaker can be much lower than its impedance---until the speaker starts moving and generates a back EMF (raising its impedance), the current can be very high. A high current amp design may very well perform better for transient response.


The impedance curve of the speaker reveals ALL. At DC, the coil of any speaker is not moving. Most drivers rated at 4 ohms nominal impedance have a DC coil resistance of 3 ohms. If your amp can drive 3 ohms ... meaning, it can supply enough current to sustain the driven voltage across a 3 Ohm resistor ... it will be indistinguishable from any other amp, even if the other amp has 1000x the current delivering capacity, able to drive a 0.003 ohm resistor to the same voltage.

But the real point is : the current is determined by the load, not the amp (until the amp current-limits), no matter if it's advertised as "high current" or not. This is a simple consequence of the amplifier emulating an ideal voltage course.

Finally, "DC" and "transient" are completely opposite concepts. "Transient" is, by definition, a short-term (therefore high-frequency) effect, while "DC" is a long-term (therefore low-frequency) effect. Consequently, the ability of an amplifier to drive the DC coil resistance will have zero impact on transient performance.

A better argument would have been electrostatic speakers, whose _high frequency_ impedance can drop to scary-low levels (due to their capacitive nature). Here, an amplifier may exhibit transient difficulties if it can't deliver the required current.

But in any case ... the driven voltage is determined by the amplifier, the drawn current is determined by the load.


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## chad (Jun 30, 2005)

werewolf said:


> But the real point is : the current is determined by the load, not the amp (until the amp current-limits), no matter if it's advertised as "high current" or not. This is a simple consequence of the amplifier emulating an ideal voltage course.


One thing I like to explain to people is that a "high current" amplifier is simply an advertisement that states that the amplifier can handle low impedance loads without the power supply/final section falling to it's knees.

Yes an old PG MS275 is high current, but at 4 ohms puts out just as much power AND CURRENT as any other amplifier with the same rating... because the rail voltage is the same. BUT the MS275 has a substantial power supply AND the output section that allows it to be stable at insanely low impedance loads, thus allowing the marketing department to claim "high current" when in fact any understanding of ohm's law would make that a given 

Chad


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## durwood (Mar 7, 2007)

chad said:


> One thing I like to explain to people is that a "high current" amplifier is simply an advertisement that states that the amplifier can handle low impedance loads without the power supply/final section falling to it's knees.
> 
> Yes an old PG MS275 is high current, but at 4 ohms puts out just as much power AND CURRENT as any other amplifier with the same rating... because the rail voltage is the same. BUT the MS275 has a substantial power supply AND the output section that allows it to be stable at insanely low impedance loads, thus allowing the marketing department to claim "high current" when in fact any understanding of ohm's law would make that a given
> 
> Chad


Exactly, just like the old soundstream amps too. Note how the power ratings go down when you switch the amp to "high current" mode IF you keep the load the same. Those of course are the same amps that advertise themselves as "Class A" even though they are not true class A. Marketing...


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## Guest (Aug 29, 2007)

Fellippe said:


> I couldn't get a degree in EE without knowing Ohm's law, Kirchoff's Current & Voltage Laws, Thevenin/Norton with dependent and independent sources, small/large signal analysis of BJTs, MOSFETS, etc.
> 
> There's no confusion here, Werewolf.
> 
> Where the confusion lies is hearing differences in similar rated amps, and seeing some amps with lower ratings outperform those with higher ratings. You choose to believe a watt is a watt (which is fine), and I after having these experiences begin to QUESTION whether that's true.


Wrong. I never said "a watt is a watt" ... in fact, i've argued VIOLENTLY to the contrary. We can set up a 1kHz _sine_ wave, delivering exactly 1 watt into a louspeaker, and compare it to a 1kHz _square_ wave, also delivering exactly 1 watt to the loudspeaker. I promise ... I can hear the difference. And I know exactly why ... it's because all watts are NOT the same. Regarding the ability to hear differences in amps ... first, prove the difference exists in a double-blind test. Then, prove that the difference cannot be attributed to : gain, power, frequency response, noise or distortion. Until then, what you've heard is a frequency response, gain or power error ... nothing more. This has been demonstrated time and again ... it has nothing to do with an amp trying to force a voltage _and_ current to a load. But it has everything to do with the FACT that amplifiers sound different!



> My problem here is that I propose a theory from someone who thought it out a bit, and all that anyone has been able to come up with is to wait around to find a way to use Ohm's law to disprove it???


No need to wait. If the theory is disproven by Ohm's Law, as I have done, the theory is junk. I'm sorry to disappoint you.



> Is real world resistance always fixed??? Is that first poster who suggested the resistance is the same automatically correct? (Are you automatically correct?)


No, resistance is not always "fixed". But as i've tried hard to demonstrate, if we don't understand how a "fixed" resistor works, how can we hope to understand something more complicated?



> The concepts of current and voltage take a good amount of time to truly "get". I=V/R is simple math, but understanding what current really is and what voltage ("potential difference") is takes time. Did anyone care to read or even challenge the thought that "current" controls speakers better than "voltage" does.....the only argument was to spin it that they'd always be equal, invalidating the hypothesis.
> 
> Look Wolf, I'm not even claiming to be an EE know it all....just throwing out ideas that sound good on paper. On a daily basis I see the difference between using single phase 120/208, three phase 120/208, and three phase 277/480, and how the effects of going up in voltage are beneficial in reducing current.
> 
> You're barking up the wrong tree if you think I don't "get" simple EE, and I'll go out on a limb and say that your mastery of EE concepts reeks a lil more Ph.D. than P.E.


thanks for the compliment!


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## Guest (Aug 29, 2007)

Fellippe ...

I'm not trying to be a jerkoff. All i'm asking, as gently as i can, is this :

Before we discuss a "new way to look at amplifier power", can we please understand the "old way"? It's been my experience that many who love to debate amplifier tests and measurements, do not even understand the fundamental foundations of basic electronics.

If that doesn't include you, my apologies.


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## MarkZ (Dec 5, 2005)

exmaxima1 said:


> One of the first things I learned out of school was that "transistors are the world's fastest fuses". It is doubtful that a fuse will blow fast enough to save an output stage. Plus, many transistors fail from exceeding their SOA (safe operating area) due to elevated temperatures. When the temps go up, the current ratings go WAY down. It would be near impossible for fuses to reliably protect against that.


There are instances where the SOA of the transistor isn't ideal for the design, and so the current may be the bigger factor if you're pushing it on the low slope part of the SOA curve. The rail fuses aren't going to do much save the output devices (although I guess they could for a mono amp). Also, if the output devices fail short then the output fuses might be able to save the speakers.


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## Oliver (Jun 25, 2007)

So if a high current amplifier is the way to go, then you will need to get some speakers rated as low as possible ohmage wise.

Some 2 ohmers for the components, or a combination of 4 ohmers in parallel.

A sub with DVC 1 ohm coils in parallel for 1/2 an ohm, should do the trick.

And by all means, please, let us know what your findings are!!


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## MarkZ (Dec 5, 2005)

Hic said:


> So if a high current amplifier is the way to go,


How did you arrive at that conclusion based on what everyone has said here?


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## Oliver (Jun 25, 2007)

Quote[The concepts of current and voltage take a good amount of time to truly "get". I=V/R is simple math, but understanding what current really is and what voltage ("potential difference") is takes time. Did anyone care to read or even challenge the thought that "current" controls speakers better than "voltage" does.....the only argument was to spin it that they'd always be equal, invalidating the hypothesis.]quote 

Not everyone, there is one person who is suggesting this and a test to determine it, or help validate his thoughts would be what I have suggested.

If this is still confusing to you I would submit the above ^^^^ words, beginning of sentence[" Did anyone...."

MarkZ, does this help....
Quote[Therefore, an amp which creates power by producing high current has better control over conventional loudspeakers than an amp which produces high voltage but low current. So in this case, as you hypothesized, current would be analogous to torque where voltage might be analogous to HP. And just as engine RPM relates the two under the hood, the impedance of the speaker relates the two inside the amplifier.]quote


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## Oliver (Jun 25, 2007)

excerpt/Quote[...and how the effects of going up in voltage are beneficial in reducing current.]quote 

I would submit that Georg Ohm proved this!!

Unless I misunderstood his law, I thought there was an inverse relationship between the two 

Or, in other words, if one of them goes up, the other one of them goes down.


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## Fellippe (Sep 15, 2006)

Hic said:


> and how the effects of going up in voltage are beneficial in reducing current.
> 
> I would submit that Georg Ohm proved this!!
> 
> ...


Well yeah..

I was just saying that the benefit of reduced current is smaller wiring/conduit.

A wire is sized for a certain amount of amps, regardless of input voltage...e.g. 120, 208, 277, 480, etc.

But that's another thread.


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## Fellippe (Sep 15, 2006)

werewolf said:


> Fellippe ...
> 
> I'm not trying to be a jerkoff. All i'm asking, as gently as i can, is this :
> 
> ...


It's cool, no beef.

What are your thoughts on Darlington transistors for the output stage?

How does that rank up with other types of output stages?


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## durwood (Mar 7, 2007)

.


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## Guest (Aug 29, 2007)

Hic said:


> The concepts of current and voltage take a good amount of time to truly "get". I=V/R is simple math, but understanding what current really is and what voltage ("potential difference") is takes time. Did anyone care to read or even challenge the thought that "current" controls speakers better than "voltage" does.....the only argument was to spin it that they'd always be equal, invalidating the hypothesis.
> 
> Not everyone, there is one person who is suggesting this and a test to determine it, or help validate his thoughts would be what I have suggested.
> 
> ...


i give up 

But before i do ...

I need to deliver 100 watts to a 4 ohm speaker. What's wrong with this WHOLE discussion :

- Amplifier A will deliver that power at a high voltage, but low current. Amplifier A is like a high horsepower, but low torque motor.

- Amplifier B will deliver that power at a low voltage, but high current. Amplifier B is like a high torque, but low horsepower motor.

And since we know that current is what really controls the speaker, it's better to choose the "high current" ... like, high torque ... Amplifier B.

What's wrong with this. WHAT'S WRONG WITH THIS? PLEASE, i'm ****ing begging !!!!

And you guys think i'm crazy for suggesting that even those who profess to be EE's, don't even understand Ohm's Law ... and we should seriously entertain these alternate ways to look at an amplifier's power delivery? Before anyone even demonstrates a mastery of a simple voltage source?


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## SteveLPfreak (Sep 26, 2005)

werewolf said:


> i give up


Please don't give up. Myself and many others really enjoy reading your posts.


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## 89grand (Nov 23, 2006)

werewolf said:


> i give up


Yeah, can't say I blame you. 

I thought everything was clear on this whole "high current" thing, but apparently not.

Let me try. 

*"High Current" amps do not have "more current" at any given load than a "High Voltage" amps. It's a marketing name to describe amps that have the ability to deliver power into low impedances. 100 watts from a "High Voltage" amp into a 4 ohm load is the same as 100 watts from a "High Current" amp into a 4 ohm load.*


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## aneonrider (Apr 28, 2007)

werewolf said:


> i give up
> 
> But before i do ...
> 
> ...


Amplifier A = Amplifier B

No matter what, to get 100W out of an amplifier at a 4 ohm constant load, you will have 20V/5A of output.

I cannot believe this is still going.


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## Guest (Aug 29, 2007)

aneonrider said:


> Amplifier A = Amplifier B
> 
> No matter what, to get 100W out of an amplifier at a 4 ohm constant load, you will have 20V/5A of output.


yeah but the "high current" amp will be different! It has to ... it's high current!!! You must be a PhD type ... no practical knowledge at all !!!     

Thank you. Please, I encourage everyone to understand this answer thoroughly. There's nothing more I can add to this topic.


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## aneonrider (Apr 28, 2007)

Here, I'll break it down for people slow to the show... werewolf was trying to get you to do this yourself, but....

We have TWO known variables, power & impedance (or load).

Therefore we have two possible equations:

P=I^2*Z OR P=V^2/Z

That is IT.

As impedance decreases, current increases & voltage decreases. As impedance increases, current decreases & voltage increases.

Like, 1st week of EE here.


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## Oliver (Jun 25, 2007)

Fellippe said:


> It's cool, no beef.
> 
> What are your thoughts on Darlington transistors for the output stage?
> 
> How does that rank up with other types of output stages?


If you purchase an amplifier with "Triple Darlington" outputs, you will be happy!!


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## Neil (Dec 9, 2005)

aneonrider said:


> Like, 1st week of EE here.


Like, 1st week of grade 10 Physics, eh Scott?

I don't understand why power is so misunderstood...in virtually every aspect.


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## Oliver (Jun 25, 2007)

werewolf said:


> i give up
> 
> But before i do ...
> 
> ...


Werewolf, my apologies for not quoting the original poster, I just highlighted and copied it  , I have gone back and tried to modify it.

Also, brought up another thread that might help from pg 9.


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## Guest (Aug 29, 2007)

Hic said:


> Werewolf, my apologies for not quoting the original poster, I just highlighted and copied it  , I have gone back and tried to modify it.
> 
> Also, brought up another thread that might help from pg 9.


no apologies mi amigo ... but this particular topic has been played out, in my opinion. I'm out!


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## CaseyWalsh (Jul 25, 2005)

These folks try to explain how voltage and current limiting affect an amplifier’s performance under various loads – including reactive ones. But then again, they are trying to sell something...

http://www.audiograph.se/


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## aneonrider (Apr 28, 2007)

Punk0Rama said:


> Like, 1st week of grade 10 Physics, eh Scott?
> 
> I don't understand why power is so misunderstood...in virtually every aspect.


Well, ya, but our school system is a bit different


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## MarkZ (Dec 5, 2005)

Hic said:


> excerpt/Quote[...and how the effects of going up in voltage are beneficial in reducing current.]quote
> 
> I would submit that Georg Ohm proved this!!
> 
> ...


To maintain equal power levels, sure. [that's not ohm's law, however] 

But amplifiers don't work like that. If amplifier voltage goes up, then so too will current because we're holding impedance constant (ie. making the comparison using the same speaker). If instead you want to compare X watts through a 1 ohm speaker vs. X watts through a 4 ohm speaker, then there's no inherent benefit to either. When the original poster said "control", he was pretty vague. Lots of people call damping factor a measure of "control" (although I sure as hell wouldn't), but that actually decreases with increasing current, all else being equal. So I don't really knwo what he's referring to exactly.


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## Oliver (Jun 25, 2007)

Why not just buy these amps? http://www.talkaudio.co.uk/vbb/showthread.php?t=225365

Read what it says under resistance http://www.the12volt.com/ohm/ohmslaw.asp


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## Oliver (Jun 25, 2007)

http://en.wikipedia.org/wiki/Ohms_Law

Is this the one we are talking about?

Here is a water analogy from the above link

While the terms voltage, current and resistance are fairly intuitive terms, beginning students of electrical engineering might find the analog terms for water flow helpful. Water pressure, measured by international units in pascals (and commonly in units of pounds-force per square inch), is the analog of voltage because establishing a water pressure difference between two points along a (horizontal) pipe causes water to flow. Water flow rate, as in liters (or gallons) of water per minute, is the analog of current, as in coulombs per second. Finally, flow restrictors such as apertures placed in pipes between points where the water pressure is measured are the analog of resistors. We say that the rate of water flow through an aperture restrictor is proportional to the difference in water pressure across the restrictor. Similarly, the rate of flow of electrical charge, i.e. the electrical current, passing through an electrical resistor is proportional to the difference in voltage measured across the resistor.


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## aneonrider (Apr 28, 2007)

Electrical resistance is the degree of opposition an object has to the flow of current.


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## aneonrider (Apr 28, 2007)

Hic said:


> http://en.wikipedia.org/wiki/Ohms_Law
> 
> Is this the one we are talking about?


Yes.


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## Oliver (Jun 25, 2007)

Then what is the other Ohms Law?


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## MarkZ (Dec 5, 2005)

Hic said:


> Why not just buy these amps? http://www.talkaudio.co.uk/vbb/showthread.php?t=225365
> 
> Read what it says under resistance http://www.the12volt.com/ohm/ohmslaw.asp


Yikes. You need to cite better sources, man.  In the second link, I think every sentence has an error in it.  And since I'm bored right now...

_"Ohm's Law defines the relationships between (P) power, (E) voltage, (I) current, and (R) resistance. One ohm is the resistance value through which one volt will maintain a current of one ampere. "_

Ohm's law says nothing about power.


_"( I ) Current is what flows on a wire or conductor like water flowing down a river. Current flows from negative to positive on the surface of a conductor. Current is measured in (A) amperes or amps. "_

Current, by convention, flows from positive to negative. This is somewhat semantic, but most engineers don't equate current flow and electron flow (although there are exceptions). I think it's misleading to say current flows from neg to positive, however. Also, in practice, it doesn't entirely flow on the surface of the conductor. This is a common misconception that people who only make it as far as electrostatics in physics make. 

_"( R ) Resistance determines how much current will flow through a component."_

Um, sometimes. But this isn't a definition of what resistance is. And the fact that it's only sometimes true (depends on the circuit) makes it an even worse attempt to define it.

_"Resistors are used to control voltage and current levels."_

Sometimes.

_"A very high resistance allows a small amount of current to flow."_

Um...unless you've got a really high voltage across the very high resistance. Then you'll still get a large amount of current flowing.

_"( P ) Power is the amount of current times the voltage level at a given point measured in wattage or watts."_

Yes, the unit is watts. But again, this isn't a definition.


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## Oliver (Jun 25, 2007)

MarkZ, can you teach me about the Ohms law where current and voltage increase?


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## aneonrider (Apr 28, 2007)

Hic said:


> Then what is the other Ohms Law?


There is only one


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## aneonrider (Apr 28, 2007)

Hic said:


> MarkZ, can you teach me about the Ohms law where current and voltage increase?


That is the one where power increases.


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## aneonrider (Apr 28, 2007)

MarkZ said:


> Current, by convention, flows from positive to negative. This is somewhat semantic, but most engineers don't equate current flow and electron flow (although there are exceptions). I think it's misleading to say current flows from neg to positive, however. Also, in practice, it doesn't entirely flow on the surface of the conductor. This is a common misconception that people who only make it as far as electrostatics in physics make.


And technically, electrons flow from negative to positive. But you mentioned convention, so yes 

Anyways:

Volts are potential difference between two points in a circuit
Current is the flow of electric charge. 1 ampere is 1 coulomb of charge flowing per second.
Resistance I already stated.

Power is the rate at which electrical energy (work) is transferred. Sound, light, heat, movement, etc are all work.


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## Oliver (Jun 25, 2007)

MarkZ, is Gravity something that is a constant like a law, or only apparent during full eclipses.

In other words, if it is a law, is it always a law, or if you think the "12 volt", website has bad grammer then gravity is no longer in effect?


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## Oliver (Jun 25, 2007)

MarkZ said:


> To maintain equal power levels, sure. [that's not ohm's law, however]
> 
> But amplifiers don't work like that. If amplifier voltage goes up, then so too will current because we're holding impedance constant (ie. making the comparison using the same speaker). If instead you want to compare X watts through a 1 ohm speaker vs. X watts through a 4 ohm speaker, then there's no inherent benefit to either. When the original poster said "control", he was pretty vague. Lots of people call damping factor a measure of "control" (although I sure as hell wouldn't), but that actually decreases with increasing current, all else being equal. So I don't really knwo what he's referring to exactly.


Doen't your statement above, make Ohms Law wrong, he states if pressure increases, flow decreases and conversely if flow rate increases, pressure decreases, all this if resistance remains constant.


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## aneonrider (Apr 28, 2007)

I think he was referring to the fact most car amplifiers do not have regulated outputs, so when the impedance decreases, power increases. Normally unregulated amps attempt to keep voltage output constant down to its lowest stable impedance, which will cause current to double for every halving of impedance, or to halve for every doubling of impedance.


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## MarkZ (Dec 5, 2005)

Hic said:


> Doen't your statement above, make Ohms Law wrong, he states if pressure increases, flow decreases and conversely if flow rate increases, pressure decreases, all this if resistance remains constant.


Bah, I knew I shouldn't have picked apart his site. 

Power _is_ related to current, voltage, and resistance. It's just not Ohm's law that makes the relation. Ohm's law simply allows us to state that V = IR. That's all. And so if voltage increases and resistance doesn't change, then current will also increase. It's not an inverse relationship.


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## Oliver (Jun 25, 2007)

I'm not sure what I thought, sorry, so yeah buy whatever the original poster was saying I'm good with that


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## exmaxima1 (May 31, 2007)

MarkZ said:


> Also, if the output devices fail short then the output fuses might be able to save the speakers.


This is a distinct possibility I overlooked. But maybe the fuse should be on the speaker then. The speaker manufacturer should have a better handle on what fuse is appropriate. A passive speaker system would likely have a DC path to the woofer, and hi-pass caps would protect the mids or tweeters. But what if the system was active and the amps were DC-coupled to mids or tweeters? The amplifier output fuse, most likely rated to the amplifier's power rating, would easily blow a delicate voice coil before the fuse.

But there is a very practical solution: The speaker does not actually need a conventional fuse. Instead an accessible fusible link could be wired to the terminal board. Similar to the fusible links buried in power transformers---a thin wire that melts before the coils do. But I digress.....


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## aneonrider (Apr 28, 2007)

Most good passive crossover designs already have slow-blow fuses to protect the tweeters.


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## Oliver (Jun 25, 2007)

Which company do you prefer, as far as purchasing your high [ current and voltage ] amps from?

I've seen some listed as high current amps and some listed as high voltage amps.

I can't think of an amplifier advertised as both, " our amps put out high voltage and high current", we can drive your subs at a 1/2 ohm and your 8 ohm components


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## aneonrider (Apr 28, 2007)

How about, amps put out power, since "putting out" is work.


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## exmaxima1 (May 31, 2007)

aneonrider said:


> Most good passive crossover designs already have slow-blow fuses to protect the tweeters.


I think you mean PTC poly circuit breakers. Or possibly light bulbs for current limiting. I have not seen fuses on crossovers in years, except on pro-sound speakers. And I don't think you would want a Slo-Blo on a tweeter---it would never pop in time. But maybe I've never seen good crossovers....

BTW, one of the most common failures for car tweeters is the installer wiring it to the lo-pass terminals (woofer outs) instead of the hi-pass (tweeter outs). You'd be surprised how many times they argue that it should be a warranty issue. Kinda like the screwdriver holes in the surrounds---WARRANTY!!

Matthew


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## aneonrider (Apr 28, 2007)

Well, I guess I really meant light bulbs.:blush:


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## JAG (May 6, 2006)

Hmmmm .... I sure wish I could spout off really cool sounding Einstien gibberish like Werewolf  ..... Actually , I just wish I could understand anything Jeff says ... LOL

But I can't. What I CAN tell you , is wether I know how or why , I do know a watt is not a watt. Because every amp i have ever listened to had it's own sonic signature.


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## ca90ss (Jul 2, 2005)

AVI said:


> I do know a watt is not a watt.


A watt as a unit of measurement is most definitely a watt. That's like saying that an inch isn't an inch.


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## chad (Jun 30, 2005)

Well Werewolf, if you are still reading.......

The power rating standard I was referring to is the EIA/CEA-490-A

It is as follows:

20ms burst at full power (THD+N <1%) followed by 480ms 20dB below full power. Representng music with a 16dB crest factor at 120BPM.

Gruppen does it with a 12dB crest factor and a 25ms burst while rating the same as CEA-490-A
I almost has it for you this afternoon but was typing in 4090-A... Grrr.

Chad


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## MarkZ (Dec 5, 2005)

Hic said:


> Which company do you prefer, as far as purchasing your high [ current and voltage ] amps from?
> 
> I've seen some listed as high current amps and some listed as high voltage amps.
> 
> I can't think of an amplifier advertised as both, " our amps put out high voltage and high current", we can drive your subs at a 1/2 ohm and your 8 ohm components


There used to be lots of manufacturers with high-v/high-i switches. One of my amps (ESX Quantum) has a sophisticated version of that.


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## MarkZ (Dec 5, 2005)

exmaxima1 said:


> I think you mean PTC poly circuit breakers. Or possibly light bulbs for current limiting. I have not seen fuses on crossovers in years, except on pro-sound speakers. And I don't think you would want a Slo-Blo on a tweeter---it would never pop in time. But maybe I've never seen good crossovers....


That's what I thought at first too, but maybe a slow blow better approximates the thermal capabilities of the coil? You of course use a lower current rating.


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## JAG (May 6, 2006)

ca90ss said:


> A watt as a unit of measurement is most definitely a watt. That's like saying that an inch isn't an inch.


Watt ? Watt ??? You just leave the whole " inch " thing alone damnit ! I have my wife believing a certain way !  

Nope ... all watts do NOT sound the same


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## ca90ss (Jul 2, 2005)

AVI said:


> Nope ... all watts do NOT sound the same


Nobody said they did. What has been said is that any difference in sound between amps is measurable and not attributed to magical fairy dust.


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## JAG (May 6, 2006)

ca90ss said:


> Nobody said they did. What has been said is that any difference in sound between amps is measurable and not attributed to magical fairy dust.


Fairy dust ? I only smoked that **** once .... and I didn't even inhale


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## t3sn4f2 (Jan 3, 2007)

Bumpage


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## Oliver (Jun 25, 2007)

werewolf said:


> agreed. *The analogy is fatally flawed*.
> 
> Once you specify load impedance, you no longer have the "freedom" to say ... "I can get 100 watts with 1 volt and 100 amps, or 100 volts and 1 amp."
> 
> ...


Here is your bumpage ^ ^ ^


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## t3sn4f2 (Jan 3, 2007)

a$$hole said:


> Here is your bumpage ^ ^ ^


I bumped the thread not the opening post


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## Oliver (Jun 25, 2007)

well then since U like jibberish . . . let's talk Dr. Seuss 

Fillippe is going under FG??? something or another and prolly has quite a few more friends who don't know **** either


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## t3sn4f2 (Jan 3, 2007)

a$$hole said:


> well then since U like jibberish . . . let's talk Dr. Seuss
> 
> Fillippe is going under FG??? something or another and prolly has quite a few more friends who don't know **** either


What are you talking about? 

I bumped the thread because there is good info. there, it's stuff you don't see around much and can give you more incite on how amps work?


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## TREETOP (Feb 11, 2009)

I love it when old werewolf threads get bumped!


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## Oliver (Jun 25, 2007)

t3sn4f2 said:


> What are you talking about?
> 
> I bumped the thread because there is good info. there, it's stuff you don't see around much and can give you more incite on how amps work?


My Bad :blush:

continue on . . .


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