Dynamic Headroom?
Guest
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What? Amplifiers have a 'sound'? I thought they all sounded the same... 
[img]graemlins/thumb.gif[/img] [img]graemlins/bs.gif[/img]
Anyways, I guess my ramblings were pretty much backed by your posted articles. If you want 3dB of headroom, buy twice as much power..and so on into oblivion
In all honesty, you can't have anough power.. I recall reading that a symphony can produce SPL readings over 120 dB.. with a small speaker array, given the size of the room and distance from the speakers, you need something like 40,000W to recreate the performance. Slick, but ain't gonna happen.
You can't make power from nowhere, and maximum power is maximum power. Again, there is no peak power, no dynamic power, no ILS power. You have max power at a specific amount of distortion. I chose 1% for my testing because anything above that becomes pretty clearly audible.
John, people are more than welcome to disagree with me. It more often than not presents a different way of looking at a topic or problem, and I learn from it.
[img]graemlins/thumb.gif[/img] [img]graemlins/bs.gif[/img] Anyways, I guess my ramblings were pretty much backed by your posted articles. If you want 3dB of headroom, buy twice as much power..and so on into oblivion
In all honesty, you can't have anough power.. I recall reading that a symphony can produce SPL readings over 120 dB.. with a small speaker array, given the size of the room and distance from the speakers, you need something like 40,000W to recreate the performance. Slick, but ain't gonna happen.
You can't make power from nowhere, and maximum power is maximum power. Again, there is no peak power, no dynamic power, no ILS power. You have max power at a specific amount of distortion. I chose 1% for my testing because anything above that becomes pretty clearly audible.
John, people are more than welcome to disagree with me. It more often than not presents a different way of looking at a topic or problem, and I learn from it.
Thread Starter
1000 Watt CAFz'r
Joined: Oct 2003
Posts: 1,783
Now this is a thread worth reading 
Dave, what a great post. I learn something pretty well every other post you make. Keep it up, there are lots of enthusiasts like myself that are thirsty for the good stuff.(real world knowledge)
I'm going to get into more trouble with the next question.
How many Joules of energy are stored in a 1 Farad capacitor?
Yes, I"m sure you think I'm going the wrong direction. But, I'm currious to see the theoretical time that the potential energy stored in an "add on" capacitor will cover. Provided that the amplifier efficiency is known, and the output into a given load is known, we should be able to determine how much time a capacitor can sustain an amplifier by itself. Then using the CA rating of a battery, you should be able to calculate the number of Joules of energy it is capable of producing in a second. I"m not going to consider a charging source like an alternator for this idea. Lets assume the engine is off, and just the stereo is running. If for example, the amplifier demands 5 joules per second, and the battery can produce 3 joules per second, how long can the capacitor fill the demand? I realize that transients in music don't happen over long periods of time (seconds), but I'd like to get a starting point to ponder how to improve the "headroom" of an amplifier. After all, if Dave is having a difficult time measuring transients in his lab, how are we to quantify headroom if the amplifier is unable to have it's current demands met in the small period of time that a transient accurs? [img]graemlins/dunno.gif[/img]
Where is Dukk anyway?
Adam
Dave, what a great post. I learn something pretty well every other post you make. Keep it up, there are lots of enthusiasts like myself that are thirsty for the good stuff.(real world knowledge)
I'm going to get into more trouble with the next question.
How many Joules of energy are stored in a 1 Farad capacitor?
Yes, I"m sure you think I'm going the wrong direction. But, I'm currious to see the theoretical time that the potential energy stored in an "add on" capacitor will cover. Provided that the amplifier efficiency is known, and the output into a given load is known, we should be able to determine how much time a capacitor can sustain an amplifier by itself. Then using the CA rating of a battery, you should be able to calculate the number of Joules of energy it is capable of producing in a second. I"m not going to consider a charging source like an alternator for this idea. Lets assume the engine is off, and just the stereo is running. If for example, the amplifier demands 5 joules per second, and the battery can produce 3 joules per second, how long can the capacitor fill the demand? I realize that transients in music don't happen over long periods of time (seconds), but I'd like to get a starting point to ponder how to improve the "headroom" of an amplifier. After all, if Dave is having a difficult time measuring transients in his lab, how are we to quantify headroom if the amplifier is unable to have it's current demands met in the small period of time that a transient accurs? [img]graemlins/dunno.gif[/img]
Where is Dukk anyway?
Adam
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IF I recall correctly... 1 Joule is the amount of energy dissipated at a level of 1-Watt (of course, for 1 second).
And I think the energy stored in a capacitor is
E= ((C x V)^2)/2
Where E= Energy in Joules, C= Capacitance and V= Volts. Let's look at a real-world example. The output 'stiffening' caps on an amp I reviewed recently had about 10,000 uF of capacitance and I think the rail voltage was around 35V.. This gives us ((.01x35)^2)/2 = 0.06 Joules, or 0.06 Watts for one second...
Let's look at a stiffening capacitor. Assuming they are really one Farad, and we are running them at about 13 Volts. Using the same equation we get 84.5 Joules of Energy... Far more impressive. And is more better? Yes, so long as the internal resistance of the device will allow the energy to be released fast enough.
And I think the energy stored in a capacitor is
E= ((C x V)^2)/2
Where E= Energy in Joules, C= Capacitance and V= Volts. Let's look at a real-world example. The output 'stiffening' caps on an amp I reviewed recently had about 10,000 uF of capacitance and I think the rail voltage was around 35V.. This gives us ((.01x35)^2)/2 = 0.06 Joules, or 0.06 Watts for one second...
Let's look at a stiffening capacitor. Assuming they are really one Farad, and we are running them at about 13 Volts. Using the same equation we get 84.5 Joules of Energy... Far more impressive. And is more better? Yes, so long as the internal resistance of the device will allow the energy to be released fast enough.
Guest
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Oh I'm around. Dynamic headroom - as we are seeing, is a tough topic to nail down and, as Dave found, is damn tough to measure/prove. Thus I choose the amp I want (cuz they DO all sound the same [img]graemlins/thumb.gif[/img] ) and use it and do not worry what the rated headroom on it is compared to the actual headroom I am achieving [img]graemlins/dunno.gif[/img]
And Bob Carver is certainly an Engineer's Engineer but he is ALSO a Marketing genious of the magnitude of Amir Bose so I read all his propaganda with a grain of salt [img]graemlins/thumb.gif[/img]
And Bob Carver is certainly an Engineer's Engineer but he is ALSO a Marketing genious of the magnitude of Amir Bose so I read all his propaganda with a grain of salt [img]graemlins/thumb.gif[/img]
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I always forget to trash Bose on here.. What a fool I am..
As we used to say... No highs, no lows, must be Bose.
Even my father has 'taken on' more than one of their salespeople in the Bose Stores in the US after listening to their stuff.. gotta admit, they aren't afraid to try new things...
They just filed a patent for a curvilinear versionof their acoustic wave labyrinth that's kinda neat.. I still don't want one..
As we used to say... No highs, no lows, must be Bose.
Even my father has 'taken on' more than one of their salespeople in the Bose Stores in the US after listening to their stuff.. gotta admit, they aren't afraid to try new things...
They just filed a patent for a curvilinear versionof their acoustic wave labyrinth that's kinda neat.. I still don't want one..
Hey Bose can't be that bad, they make a TON of sales every year....that's probably as you said, marketing and not product quality, I'd pay the extra bucks for a set of Martin Logan's( if I had money) just because I hate most things that are mainstream like Bose or Sony although I seen Sony's $3000+ recievers, there pretty sweet.
Guest
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Whu?? Have you listened to them??? I'd rather have some nice 6x9s in some big ported enclosures!
I listened to some Bose 901's at a shop in Niagara Falls. Though it did produce an OK image, the tonal balance was hideous.. That just wasn't what Jennifer Warnes sounded like.
Folks, wether or not you believe it, almost everything you see was created by the marketing department, not the engineers behind the product. Do a searth on "Dynamic Headroom" on Google, the results have nothing to do with what we are talking about here. You can't imagine the stuff I see, and filter, before finishing my test reports...
I listened to some Bose 901's at a shop in Niagara Falls. Though it did produce an OK image, the tonal balance was hideous.. That just wasn't what Jennifer Warnes sounded like.
Folks, wether or not you believe it, almost everything you see was created by the marketing department, not the engineers behind the product. Do a searth on "Dynamic Headroom" on Google, the results have nothing to do with what we are talking about here. You can't imagine the stuff I see, and filter, before finishing my test reports...
Thread Starter
1000 Watt CAFz'r
Joined: Oct 2003
Posts: 1,783
What change are you getting ready for Dave?
A while ago you talked about doing some testing with an Active vs Passive front stage. Have you been toying with the idea anymore. I might be able to do something like that myself, but I'm waiting for wife approval on 2 more amps. (I've got a 3 way.) It would be interesting to see how headroom plays into the sound of a totally Active vs. Passive front stage.
I"ve got some Pyramid Gold amps for ya Dukk
Adam
A while ago you talked about doing some testing with an Active vs Passive front stage. Have you been toying with the idea anymore. I might be able to do something like that myself, but I'm waiting for wife approval on 2 more amps. (I've got a 3 way.) It would be interesting to see how headroom plays into the sound of a totally Active vs. Passive front stage.
I"ve got some Pyramid Gold amps for ya Dukk
Adam
