Yeah, a lot of these things I don't have a perfect grasp on. I'm re-reading what you've written and it does make sense. I had always thought about it as higher numbers, up to a point were responsible for "pulse response linearity" I guess is the right way to say it.
Is there another word for that, or is that essentially a non issue at all? Or is it completely dictated by driver parameters?
Lets stick with sealed boxes (2nd order systems) to keep things simple. There is a total system Q that is a combination of the mechanical damping factors (such as loss in the surround or loss in the cabinet stuffing) and electrical damping factors.
We refer to the system Q's they create as Qm and Qe. Generally we want Qe to be low and Qm (mechanical) to be high because that gives us a little higher sensitivity, that is we want the majority of our damping to be electrical. In the end there is a total Q from the parallel combination of the two. If we want flattest response to resonance then we will shoot for a Q total of .7 (2nd order systems only! 4th order systems need two different Qs).
Usually for Qe (electrical Q) we assume a best case of zero output impedance driving the woofer, but if we have nonzero source impedance then the electrical Q will rise. Note that DC resistance of the voice coil is in the mix also. Even with infinite amplifier damping we only have so much effective damping because DCR gets in the way. This is another way to understand why extremly high damping factors don't do much: even with dropping the amplifier Z to zero (infinite damping) you will still have the DCR in the mix preventing infinite damping.
There is an impulse response or step response associated with any 2nd order system of a given Q. Generally low ringing is a good thing when we view impulse response, and yes, lower Q will give lower ringing. The trouble is that improving the impulse ringing comes at the expense of damping out the bass. You could have a system with a Qt of 0.1, and its impulse would be wonderfully well damped, but it would have no bass!
Thats my only problem with the Wikipedia quote, that they imply more damping means a better impulse response ("tight control") and that more is always better. In fact there is an optimum Q, and an optimum bass response that comes from that Q and therefore an inevitable amount of ringing that also comes along with that Q.
Hope it all makes sense,
David
p.s. TerryO, good quote.
I'm a little thick when it comes to math, but I'm trying!
There is more in the article that goes on to say that after a DF of about 50 or so, it really doesn't make much difference. There's also some mention of older amplifiers that have selectable damping, like 1/5/50.
What you say makes sense though. I'm taking away that there should be a magic number that tends to work well?
There is more in the article that goes on to say that after a DF of about 50 or so, it really doesn't make much difference. There's also some mention of older amplifiers that have selectable damping, like 1/5/50.
What you say makes sense though. I'm taking away that there should be a magic number that tends to work well?
The problem with the magic number is that all other factors would have to be known, that is cables, crossover, drivers. This is a bit unrealistic other than a situation with an active speaker, and these have a hard time selling to a larger market.
Best Regards,
TerryO
It's from a former "Bass List" member which carries a certain crediabilty all by itself!
Your explainations are quite good as well.
I have to admit that I once believed in the "The Iron Grip of Control that a high damping factor gives", but sadly had to abandon that notion some years ago, when faced by reality.
It was like losing an old, familiar friend.
Best Regards,
TerryO
I have to admit that I once believed in the "The Iron Grip of Control that a high damping factor gives", but sadly had to abandon that notion some years ago, when faced by reality.
It was like losing an old, familiar friend.
Kinda like when you suddenly realize as a child that there's no way 300lb philanthropist in fluffy red clothes could ever fit down your chimney?
haha.
My take on what Speaker Dave above has said is DF is a bogus concept. What IS of concern is the Q of the matching of an amplifier and loudspeaker system. Source impedance of the amplifier is important in terms of the extent to which it does or doesn't push Q of the amp/ speaker system outside what the designer would consider to be a desirable range.
I do realize that I'm discussing only one side of the two sides that Speaker Dave points to as being affected by source resistance of the power amplifier.
-Pete
I do realize that I'm discussing only one side of the two sides that Speaker Dave points to as being affected by source resistance of the power amplifier.
-Pete
Ok, TerryO is no longer "World's Worst Mathematician" that title now goes to DrDyna, Congrats
You just take that back Mister!
Nobody, and I mean nobody, comes close to my level of mathematical inability!
Dr.Dyna? Ha! Not even close.
Ok, TerryO is no longer "World's Worst Mathematician" that title now goes to DrDyna, Congrats
LOL!
<3
Hi,
FWIW wiring two drivers in series increases the damping factor for directly
driven drivers. In practice how high the DF is, is limited by inductor DCR.
But if DF is low due to significant amplifier resistance, series will up it.
Also FWIW series wired drivers can (not always do) have some weird
problems approaching the excursion limits due to interactions between
the coils that don't happen is parallel.
for transistor amps the specced DF is pretty meaningless above around 20.
rgds, sreten.
FWIW wiring two drivers in series increases the damping factor for directly
driven drivers. In practice how high the DF is, is limited by inductor DCR.
But if DF is low due to significant amplifier resistance, series will up it.
Also FWIW series wired drivers can (not always do) have some weird
problems approaching the excursion limits due to interactions between
the coils that don't happen is parallel.
for transistor amps the specced DF is pretty meaningless above around 20.
rgds, sreten.
From the very person that started me wondering about how this all tied together!
Hi Greg!
Best Regards,
Terry
Greets!
Yeah, what was that thread? 'Q for the Qless' or some-such. As already noted, it's all about getting the desired system Q and why for serious [by my standards] HIFI we need to get back to field coil drivers and variable DF electronics. Pass Labs F1/whatever type amps shouldn't be a budget buster if mass produced, though of course drivers would be more expensive in general.
Horns are finally making a bit of a comeback after a ~ 50 yr hiatus out in the deep fringe, so maybe Wild Burro's FC Betsy will jump start the next 'new thing'. Then again, the way the world's economy, [over] population is heading and the incredible advancement in DSP and materials technology in recent years it may not be too long before we're literally listening to talking pictures or even murals mounted on the walls...........
GM
I can hijack my own thread? Since so many gurus are on this thread... can you wire a 8 inch to a 6 inch with no crossover and let them work together the idea is that the six inch will naturally emphasize the higher and the 8 the lower.... the drivers from the same family? Don't beat me up... this is how we learn. I am thinking of an open baffle.
I can hijack my own thread? Since so many gurus are on this thread... can you wire a 8 inch to a 6 inch with no crossover and let them work together the idea is that the six inch will naturally emphasize the higher and the 8 the lower.... the drivers from the same family? Don't beat me up... this is how we learn. I am thinking of an open baffle.
I suppose
, it would depend on the drivers natural rolloff's, sensitivity, and... everything else. what drivers are you thinking about using?
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