Because very low is much less than 1. ie output impedance greater than speaker impedance.
dave
This has been explained to you before as I recall. Damping factor is a unitless (and in my view rather useless) measurement which is taken as the load impedance [Zl] in ohms divided by the output impedance of the source [Zs] in ohms.
In other words, look at the impedance plot of your loudspeaker and pick its lowest point. That is Zl. Divide that by the output impedance of your amplifier and you get a number for the unitless Damping Factor [DF].
Say your loudspeaker's lowest impedance is 3.6ohms, and your amplifier has an output impedance of 2.4ohms. Therefore since DF = Zl/Zs
DF = 3.6 / 2.4
DF = 1.5
In other words, look at the impedance plot of your loudspeaker and pick its lowest point. That is Zl. Divide that by the output impedance of your amplifier and you get a number for the unitless Damping Factor [DF].
Say your loudspeaker's lowest impedance is 3.6ohms, and your amplifier has an output impedance of 2.4ohms. Therefore since DF = Zl/Zs
DF = 3.6 / 2.4
DF = 1.5
Not especially, it just means it has nominal 16ohm output taps. This is not the same as output impedance or damping factor.
Now I understood! 👍
What I not understood yet is, how to know if the damping factor of an amp, is too high for the fostex fe208Ez, or is optimum?
I would like to try an analogy to test my understanding of Qts and output impedance. Feel free to make suggestions.
A speaker driver is like a race car, taking corners really fast. Of course, it has to have just the right amount of brakes applied, or else it will either crash or go too slow. Well, between the amp and the driver, the job of braking is split up. If the amp is solid state, it has hardly any brakes (low output impedance), so most of the braking has to be done by the driver (high Q). If the amp is of the SET type, it has great big strong brakes (high output impedance), so very little braking needs to be done by the driver (low Q).
A speaker driver is like a race car, taking corners really fast. Of course, it has to have just the right amount of brakes applied, or else it will either crash or go too slow. Well, between the amp and the driver, the job of braking is split up. If the amp is solid state, it has hardly any brakes (low output impedance), so most of the braking has to be done by the driver (high Q). If the amp is of the SET type, it has great big strong brakes (high output impedance), so very little braking needs to be done by the driver (low Q).
This part should be, a low output impedance amp is expected to supply almost all the damping — all electrical -- as the output impedance increases the speaker/box need to provide more of the damping.
Note that the Q of interest is the Qm (mechanical), usually you want the Qm to get closer and closer to flat, but it isn’t just that, because the Fostex FExx6 have fairly high Qm.
Then one has to talk about the change/increase in Qt when output impedance climbs and how that changes the mass corner (an important number for any BLH).
dave
Also, need to learn/understand the [T/S] driver specs and how they interact and WRT to the fact that Qes' [[Qes+ RS] = effective motor strength]] is the dominating spec of all box design until its Vas spec [compliance] becomes very large: Thiele Small parameters equations - How each one affects the others
GM
"Originally Posted by Scottmoose View Post
This has been explained to you before as I recall. Damping factor is a unitless (and in my view rather useless) measurement which is taken as the load impedance [Zl] in ohms divided by the output impedance of the source [Zs] in ohms.
In other words, look at the impedance plot of your loudspeaker and pick its lowest point. That is Zl. Divide that by the output impedance of your amplifier and you get a number for the unitless Damping Factor [DF].
Say your loudspeaker's lowest impedance is 3.6ohms, and your amplifier has an output impedance of 2.4ohms. Therefore since DF = Zl/Zs
DF = 3.6 / 2.4
DF = 1.5"
So far this was the better explanation that I understood, about how a damping factor is calculated.
Now I understood why damping factor is a unitless measurement, and how to calculate..
but when reading again, a doubts appeared, let's say that I will to this calculation that Scott taught me.
I understood how to look at the speaker's impedance graphic, and find the lowest point, in order to know the ZI.
Now: "Divide that by the output impedance of your amplifier"
I noticed that mostly manufacturers describe the output impedance like this:
Leben Hi-Fi Stereo Company
OUTPUT IMPEDANCE 4/6/8 Ohms (Selectable)
But this is not output impedance, they are just the speakers terminal, doesn't? not the actual output impedance about the amp...
but when reading again, a doubts appeared, let's say that I will to this calculation that Scott taught me.
I understood how to look at the speaker's impedance graphic, and find the lowest point, in order to know the ZI.
Now: "Divide that by the output impedance of your amplifier"
I noticed that mostly manufacturers describe the output impedance like this:
Leben Hi-Fi Stereo Company
OUTPUT IMPEDANCE 4/6/8 Ohms (Selectable)
But this is not output impedance, they are just the speakers terminal, doesn't? not the actual output impedance about the amp...
Then you have a lot to learn about the electrical, mechanical, acoustical theories behind them that are normally taught at a technical college.
GM
Okay, let me try to understand this:
The method that Scott taught me, is the way to know the measurement of an amp's damping factor.
Now this method, is to know the same thing, but on the measurement of output impedance (aka as damping factor too), is just the another measurement language for the same thing.
Correct?
By the way... the amp's output impedance, that I have to use on this formula, it's not this? right?
"OUTPUT IMPEDANCE 4/6/8 Ohms (Selectable)"
As is described on the Leben integrated CS-300X for example...
Leben Hi-Fi Stereo Company
Even they describing as output impedance, this are just the speaker's terminals.... not the real output impedance of the amp, correct?
In order to know the real amp's output impedance, there's another calculation to be done, that is what GM is trying to teach me...
Correct?
Thanks!
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