Wow, just wow!
One thing I've learned...Less is more....But more is better.
Seriously though, I had them sitting around not doing anything so I brought them home.
For those that don't know how ELF works:
Take a woofer in a small sealed box. It will have a 2nd order rolloff below resonance. Now EQ it such that you "rotate" the response around the resonance such that the fall-off below resonance is flat, and the flat response above resoance now falls off 3md order. This requires a large increase in excursion as you go low.
dave
Take a woofer in a small sealed box. It will have a 2nd order rolloff below resonance. Now EQ it such that you "rotate" the response around the resonance such that the fall-off below resonance is flat, and the flat response above resoance now falls off 3md order. This requires a large increase in excursion as you go low.
dave
This requires a large increase in excursion as you go low.
Not for a given SPL, compared to a (larger) sealed box. Excursion remains the same for equivalent freq/spl. Vented/Passive Radiator/TLs all have excursion minimizing behavior that changes this somewhat, but compared to (larger) sealed, ELF keeps excursion constant for a given output, but requires more power to get there.
I know YOU know, dave, but important to be clear for those who don't.
Not for a given SPL, compared to a (larger) sealed box. Excursion remains the same for equivalent freq/spl. Vented/Passive Radiator/TLs all have excursion minimizing behavior that changes this somewhat, but compared to (larger) sealed, ELF keeps excursion constant for a given output, but requires more power to get there.
I know YOU know, dave, but important to be clear for those who don't.
As mr.doom already pointed out, the driver output is limited by it’s Xmax, as the drive level is boosted by Bag End's ELF processing down low to keep a flat frequency response, excursion also increases with that power, as it does with any sealed woofer.
The driver's response is filtered to achieve flat LF response, but its level is still excursion limited.
ELF uses a frequency dependent limiter engaged to keep LF signal from exceeding Xmax at high drive levels, referred to as “concealment”, it hides the fact that the system produces less LF than drivers with more Xmax potential.
From Bag End spec sheets:
“The ELF concealment performs dynamic control
of reducing the low frequency extension. It will
allow the system to play with the upper bass notes
unaffected while protecting the system from overload
caused by playing the lower notes louder than the
amplifier and/or loudspeaker can reproduce safely and
undistorted.”
“While the INFRASUB-18 will reproduce 8 Hz, it
is not audible nor does it have enough acoustical
power for you to feel it. The measurements
are taken at close range with sensitive instruments.
To achieve a flat response, ... full amplifier power is used at the lowest
frequencies and very little (<1 Watt) in the
upper frequency range.”
The ultimate level at any frequency is the same as any low Xmax woofer in a sealed box, and as usual, excursion rises rapidly at low frequencies, making the extension only usable at relatively low levels.
Having four 18” woofers as the OP is using is a good idea, since they can’t produce much SPL down low. Having a lot of cone area helps make up for the limited excursion capability.
Ah, this old chestnut
<large chunk removed due to length of post>
That's my thoughts anyway, now to don my fire protective suit and sit back
Well done that man (or woman). Everything you've said makes sense, and applies to things I've heard in a way I understand.
Cheers
Chris
That tune has stuff that goes down to 3Hz, if now lower. That Maelstrom is behaving exactly like I expect it would under those circumstances.
.Learn about fourier transforms of signals and you will discover that woofers dont need to be fast. Only fast enough to reproduce the highest freq. If thats a 100hz a rise time in the neighborhood of 10ms (somwher between 3 and 30 ms? Im sure someone here can do the math) this is slow. I think there is a very common misconception that a woofer playing a kick drum should look like a kick drum, it wont and it shouldn't. The "fast" part of the kick drum are the high freq. (the snap) and they will never even reach the driver. Take a kick drum signal and pass it thru a LPF and look at the wave form. You willl not see anything fast.
As for the white paper excluding mass from cone acceleration, not worth wiping my butt. The math is wrong. He makes mass a constant and ignores it. If you make it the variable it is supposed to be when your ivestigating how it affects acceleration it shows a direct dependance . And its real easy to prove: glue some mass to the driver and see how it slows down. This is so obvious you dont even have to do it. How does this kind of garbage become "popular knowledge"?
As for the white paper excluding mass from cone acceleration, not worth wiping my butt. The math is wrong. He makes mass a constant and ignores it. If you make it the variable it is supposed to be when your ivestigating how it affects acceleration it shows a direct dependance . And its real easy to prove: glue some mass to the driver and see how it slows down. This is so obvious you dont even have to do it. How does this kind of garbage become "popular knowledge"?
The Dayton is not a cheap driver by my reckoning....I'm just trying to find an explanation for a phenomenon I have observed many times, even with the expensive Adire Maelstroms as I mentioned earlier.
What two systems?
There have been many systems discussed, each has different phase, frequency, and damping response.
Each will integrate differently with the top speakers.
Each requires different processing to remotely sound similar.
Yes this is an old thread but I'm looking at providing bass augmentation to some arguably fast 15" high efficiency coaxial drivers.
What seems to be missed in the speed argument is that a high excursion 12" driver has to operate at a considerably higher speed than an 18" driver. Look at volume velocity. A 12" driver operating at 20Hz with a 1" peak to peak excision has to by definition travel at 20 inches per second. An 18" driver has 2.25 times more cone area. The distance required for the cone to move the same amount of air is 0.44". This lower displacement at the same 20Hz operating frequency requires that the driver operate at only 8.8"/second.
The slower system will have a better impedance match to the surrounding air vs merely punching holes in it as is the case with the higher velocity system. We all know the value of using larger ports than small ports in this regard.
What seems to be missed in the speed argument is that a high excursion 12" driver has to operate at a considerably higher speed than an 18" driver. Look at volume velocity. A 12" driver operating at 20Hz with a 1" peak to peak excision has to by definition travel at 20 inches per second. An 18" driver has 2.25 times more cone area. The distance required for the cone to move the same amount of air is 0.44". This lower displacement at the same 20Hz operating frequency requires that the driver operate at only 8.8"/second.
The slower system will have a better impedance match to the surrounding air vs merely punching holes in it as is the case with the higher velocity system. We all know the value of using larger ports than small ports in this regard.
Soundblaster--I'd say get the Bag End ELF--which can be had for a very reasonable price on Ebay--and be done with it. I've been running those in my system since 1996, off and on, and have always gone back to them....It is a tried and true system, no BS, no servo control, and no ridiculous excursion underhung slush motors. If it doesn't get loud enough, just add more cone surface area/power with the same processing. I've run this setup with Magnepan 20.1's, BG RD Series, open baffle cone drivers, you name it.
In the past 25 years I've listened to subs, I've never heard anything in a box come close, from my living room to 20,000 seat arenas. Pretty much all the film guys mix on them, and many recording studios mix on them....There is a reason for that.
Best,
Brett
In the past 25 years I've listened to subs, I've never heard anything in a box come close, from my living room to 20,000 seat arenas. Pretty much all the film guys mix on them, and many recording studios mix on them....There is a reason for that.
Best,
Brett
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.