AMP POWER?
10-15-2003, 01:11 PM
#1
Guest
Posts: n/a
Ok - subsequent to a point offered in another thread I offer the following scenario:
Car A
Two way component set in the front. Single amplifier @ 100 watts RMS per side through passive crossover to speakers. Assume zero power loss through the passive crossover.
Car B
Two way component set in the front. TWO amplifiers @ 50 watts RMS per side each from an active crossover. Thus there are 4 50watt channels, one for each front speaker.
Car C
Two way component set in the front. TWO amplifiers @ 100 watts RMS per side each from an active crossover. Thus there are 4 100watt channels, one for each front speaker.
Okay guys - which car has more power? Explain your reasoning.
Car A
Two way component set in the front. Single amplifier @ 100 watts RMS per side through passive crossover to speakers. Assume zero power loss through the passive crossover.
Car B
Two way component set in the front. TWO amplifiers @ 50 watts RMS per side each from an active crossover. Thus there are 4 50watt channels, one for each front speaker.
Car C
Two way component set in the front. TWO amplifiers @ 100 watts RMS per side each from an active crossover. Thus there are 4 100watt channels, one for each front speaker.
Okay guys - which car has more power? Explain your reasoning.
10-15-2003, 01:23 PM
#2
I haven't read the other thread, but simple math and logic would say the 2, 100x2 amps would have the most power as it equals 400 watts
BUT, one could say (and I believe this to be true) that theoretically the passive setup in Car A would have the same wattage to the speakers as the 100 watts of power would be divided up only in the respective frequency ranges those speakers are playing. Example, the tweets are getting 100 watts of power from 3.5k to 20k, and the mids are getting 100 watts from 3.5k down.
Power supplies not considered, it would seem Car A should have the same power as Car C. [img]graemlins/dunno.gif[/img]
BUT, one could say (and I believe this to be true) that theoretically the passive setup in Car A would have the same wattage to the speakers as the 100 watts of power would be divided up only in the respective frequency ranges those speakers are playing. Example, the tweets are getting 100 watts of power from 3.5k to 20k, and the mids are getting 100 watts from 3.5k down.
Power supplies not considered, it would seem Car A should have the same power as Car C. [img]graemlins/dunno.gif[/img]
10-16-2003, 12:18 PM
#4
In the perfect world we can assume zero power loss from passives, but we can't escape reality by using theory, now can we? [img]tongue.gif[/img]
We also need to note that the potential for producing more power is increased when using an active system. The amplifier has more headroom using an active system because the crossover section is introduced pre-amp. With passives having to split the frequency from full range output, the amp can more easily clip.
So I will have to say setup C has "potentially" more power. [img]smile.gif[/img]
We also need to note that the potential for producing more power is increased when using an active system. The amplifier has more headroom using an active system because the crossover section is introduced pre-amp. With passives having to split the frequency from full range output, the amp can more easily clip.
So I will have to say setup C has "potentially" more power. [img]smile.gif[/img]
10-16-2003, 12:52 PM
#6
Guest
Posts: n/a
"The amplifier has more headroom using an active system because the crossover section is introduced pre-amp. With passives having to split the frequency from full range output, the amp can more easily clip"
That's not entirely right. There are potentially cases where that may be true but you cannot say that overall.
That's not entirely right. There are potentially cases where that may be true but you cannot say that overall.
10-16-2003, 11:02 PM
#7
1000 Watt CAFz'r
Join Date: Oct 2003
Posts: 1,783
Got your spectacles on guys?
I’m not going to get too technical here because it’s not my forte or the point of my comments. What I am going to talk about are my ideas about amplifier power. Everybody feel free to disagree, I’ve got an open mind.
Dynamic range is one of my favorite qualities in a good audio system. Simply put, it is a system’s ability to play dynamic transients accurately. This often is defined by an amplifier’s dynamic headroom, or how much power is has in reserve. Amplifier headroom is one side of it though, the other side is having drivers that can cleanly reproduce those transients.
Having a balanced system where all of it’s components reach they’re dynamic limits together would be ideal. Most of us aren’t in that situation. Myself, I have more amplifier power than my drivers can handle. This manifests itself in cone ‘break-up’. Cone break-up is a term used to describe what happens when part of the speaker cone starts to flex. Basically, the voice-coil loses control of part of the cone. This happens for 2 reasons, they can happen independently or together. The first reason is aerodynamic, the cone starts to encounter so much aerodynamic resistance as is moves that it starts to flex. The second reason is cone mass, or I should say the reactive load that the mass of the cone puts on itself. Simply put, the outer area of the cone weighs more than the center. There is simply more cone material on the outer edges of a cone than it can support at high volumes. It starts to flex from it’s own weight as you try to increase it’s linear movement.
There is a third variable, but I don’t know much about it. You’d be hard pressed to get too much information on this subject because it is a defining characteristic of cone materials. Right now, cone material is the last great frontier for loudspeaker development. We’ve gone pretty much as far as we can go with motor and suspension technology. Sure people are always coming up with new and better drivers, but from a research standpoint, the great unknown right now is cone material. Anyway, back to my third variable, Nodes. As a cone vibrates, it has between 4 and 8 distinct hot spots if you were to map it’s acoustic output across the entire surface of the cone. The center of these hot spots radiate about 1 to 2 Db more energy than the rest of the cone. These nodes interact with each other, mostly in a positive way by pushing energy out across the cone as uniformly as possible. Well at higher volumes, nodes aren’t so friendly. I don’t know why, but I’ve been told that they are a weak point on the driver’s surface at higher volumes, AKA the upper limits of your dynamic range.
How the heck does all this speaker crap relate to amplifier power? Read on.
In the hay-day of high end home audio,(late 80s, early 90s before the recession) people used to try equipment before they bought it. I’m talking about hauling that fancy piece of gear you are thinking of buying home, and hooking it into your system. I hope that some of you get the opportunity to do this with your cars, because it’s the best way to figure out how much of anything you really need. Amplifier power should be evaluated the same way. Using the recommended RMS power handling of a speaker is a good starting point, from there you can go up or down. Many people may chose to go down in power output to put more money into the sound quality of the amp. That to me is a pretty personal choice, not one the salesperson should make for you. But some of you will get to a point where the speaker starts to distort, ideally this would be at the maximum output of the amplifier. Now all you have to do is find a 157watt amplifier for your XYZ separates!
The last point I’d like to make about amplifier power is related to headroom. I’ve heard a couple of recommendations that make sense, but the most basic one seams to fit everybody.
16 db of headroom. That is a pretty basic amount above your normal listening level. So if you have a 2-way component set with an efficiency of 92db@1w, and you like to listen at 101 db continuous,(pretty freaking loud) you will need approximately 8 watts of power. That is assuming you are 1 meter away from the drivers, a likely possibility in a car. So for the 16 db of headroom above your 101db listening level, you will need a total of approximately 300 watts. This is 300 watts from ONE amplifier. Having 2 amplifiers rated at 150watt/ch driving the midbass and tweeter indeppendantly will not give you 16db of headroom. It will give you 13db of headroom. 150 watts is still only 150 watts. If you aren’t happy with the dynamic range with 150 watts, turn down the volume or buy a bigger amp. This is of course assuming that your speakers can handle this much power.
I think if I write any more, I’ll scare some people off of the topic. So I’ll leave the benefits of bi-amplification for another time.
Or….anybody else want to talk about amplifier Damping Factors….
Adam
I’m not going to get too technical here because it’s not my forte or the point of my comments. What I am going to talk about are my ideas about amplifier power. Everybody feel free to disagree, I’ve got an open mind.
Dynamic range is one of my favorite qualities in a good audio system. Simply put, it is a system’s ability to play dynamic transients accurately. This often is defined by an amplifier’s dynamic headroom, or how much power is has in reserve. Amplifier headroom is one side of it though, the other side is having drivers that can cleanly reproduce those transients.
Having a balanced system where all of it’s components reach they’re dynamic limits together would be ideal. Most of us aren’t in that situation. Myself, I have more amplifier power than my drivers can handle. This manifests itself in cone ‘break-up’. Cone break-up is a term used to describe what happens when part of the speaker cone starts to flex. Basically, the voice-coil loses control of part of the cone. This happens for 2 reasons, they can happen independently or together. The first reason is aerodynamic, the cone starts to encounter so much aerodynamic resistance as is moves that it starts to flex. The second reason is cone mass, or I should say the reactive load that the mass of the cone puts on itself. Simply put, the outer area of the cone weighs more than the center. There is simply more cone material on the outer edges of a cone than it can support at high volumes. It starts to flex from it’s own weight as you try to increase it’s linear movement.
There is a third variable, but I don’t know much about it. You’d be hard pressed to get too much information on this subject because it is a defining characteristic of cone materials. Right now, cone material is the last great frontier for loudspeaker development. We’ve gone pretty much as far as we can go with motor and suspension technology. Sure people are always coming up with new and better drivers, but from a research standpoint, the great unknown right now is cone material. Anyway, back to my third variable, Nodes. As a cone vibrates, it has between 4 and 8 distinct hot spots if you were to map it’s acoustic output across the entire surface of the cone. The center of these hot spots radiate about 1 to 2 Db more energy than the rest of the cone. These nodes interact with each other, mostly in a positive way by pushing energy out across the cone as uniformly as possible. Well at higher volumes, nodes aren’t so friendly. I don’t know why, but I’ve been told that they are a weak point on the driver’s surface at higher volumes, AKA the upper limits of your dynamic range.
How the heck does all this speaker crap relate to amplifier power? Read on.
In the hay-day of high end home audio,(late 80s, early 90s before the recession) people used to try equipment before they bought it. I’m talking about hauling that fancy piece of gear you are thinking of buying home, and hooking it into your system. I hope that some of you get the opportunity to do this with your cars, because it’s the best way to figure out how much of anything you really need. Amplifier power should be evaluated the same way. Using the recommended RMS power handling of a speaker is a good starting point, from there you can go up or down. Many people may chose to go down in power output to put more money into the sound quality of the amp. That to me is a pretty personal choice, not one the salesperson should make for you. But some of you will get to a point where the speaker starts to distort, ideally this would be at the maximum output of the amplifier. Now all you have to do is find a 157watt amplifier for your XYZ separates!
The last point I’d like to make about amplifier power is related to headroom. I’ve heard a couple of recommendations that make sense, but the most basic one seams to fit everybody.
16 db of headroom. That is a pretty basic amount above your normal listening level. So if you have a 2-way component set with an efficiency of 92db@1w, and you like to listen at 101 db continuous,(pretty freaking loud) you will need approximately 8 watts of power. That is assuming you are 1 meter away from the drivers, a likely possibility in a car. So for the 16 db of headroom above your 101db listening level, you will need a total of approximately 300 watts. This is 300 watts from ONE amplifier. Having 2 amplifiers rated at 150watt/ch driving the midbass and tweeter indeppendantly will not give you 16db of headroom. It will give you 13db of headroom. 150 watts is still only 150 watts. If you aren’t happy with the dynamic range with 150 watts, turn down the volume or buy a bigger amp. This is of course assuming that your speakers can handle this much power.
I think if I write any more, I’ll scare some people off of the topic. So I’ll leave the benefits of bi-amplification for another time.
Or….anybody else want to talk about amplifier Damping Factors….
Adam
10-16-2003, 11:17 PM
#8
1000 Watt CAFz'r
Join Date: Oct 2003
Posts: 1,783
In response to Dukks original post at the top of the page:
Car A and car C will have the same SPL
BUT....to keep it a simple explaination, car C will have more control of the drivers. It is a simple issue of damping factor. The motion of the midbass driver in car A will feed a small amount of current back into the passive X.O. circuit, which distorts the signal going to the midrange and the tweeter. It is very small, and most people would need optimum listening conditions to hear the difference. Every amplifier has some resistance to this phenomenom and it is refered to as damping factor. The more drivers you add to an amplifier, the less damping. This is the biggest advantage of running a totaly active system AFTER the fact that each amplifier has to do less work and you have more system control and flexability with an active X.O.
Anybody looking to learn more about Damping Factor, go here:
www.eatel.net/~amptech/elecdisc/caraudio.htm
Click on topic #98 on the right side of the screen.
It's not my site, I just use it a lot to learn. Hope everybody else enjoys it.
Adam
Car A and car C will have the same SPL
BUT....to keep it a simple explaination, car C will have more control of the drivers. It is a simple issue of damping factor. The motion of the midbass driver in car A will feed a small amount of current back into the passive X.O. circuit, which distorts the signal going to the midrange and the tweeter. It is very small, and most people would need optimum listening conditions to hear the difference. Every amplifier has some resistance to this phenomenom and it is refered to as damping factor. The more drivers you add to an amplifier, the less damping. This is the biggest advantage of running a totaly active system AFTER the fact that each amplifier has to do less work and you have more system control and flexability with an active X.O.
Anybody looking to learn more about Damping Factor, go here:
www.eatel.net/~amptech/elecdisc/caraudio.htm
Click on topic #98 on the right side of the screen.
It's not my site, I just use it a lot to learn. Hope everybody else enjoys it.
Adam
10-17-2003, 05:11 AM
#10
1000 Watt CAFz'r
Join Date: May 2002
Posts: 1,649
[img]graemlins/bs.gif[/img]
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ha, ha, ha............. just joking Adam. Nice post. And, always feel free to unload like that. It's posts in that sort of vein that are good on this forum. The more info that everyone can share the better. AND you know there are a load of people here that will try and pick it all apart................ but that's all good. Regarding the cone nodes, I've seen pictures of that somewhere.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ha, ha, ha............. just joking Adam. Nice post. And, always feel free to unload like that. It's posts in that sort of vein that are good on this forum. The more info that everyone can share the better. AND you know there are a load of people here that will try and pick it all apart................ but that's all good. Regarding the cone nodes, I've seen pictures of that somewhere.
