Guys,
i just stumble upon this
on the web page it says it was used on Metallica Concerts and NASA tests
Is this a horn ?
only info i have i that it is a dual 18"
VLFC
Never mind , looks like is just a reflex with very low tuning
BUT.......
how they achieve that low tuning if the size is like of other dual 18's
KS28 below
i just stumble upon this
on the web page it says it was used on Metallica Concerts and NASA tests
Is this a horn ?
only info i have i that it is a dual 18"
VLFC
Never mind , looks like is just a reflex with very low tuning
BUT.......
how they achieve that low tuning if the size is like of other dual 18's
KS28 below
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Yeah, that's the catch isn't it?
So just song ports and the L'Acoustic style vents it seems...
At that frequency range, a cabinet of that size wouldn't be able to fit a horn that is able to drop that low with any authority (it would still behave mostly as a ported cabinet). The upper tuning frequency of a bandpass cabinet would have to drop down to 30 - 45 Hz to make any difference, in the same sized cabinet that would take away SPL from the frequencies below that.
It's the size of a standard-ish double 18" BR cabinet, that is typically tuned to 30 - 40 Hz for a good output to size ratio. Instead it's tuned an octave lower. At that size, for PA, the only sensible thing is to put in two very high excursion 18" drivers and give it tons of power.
I don't get the whole stored energy thing.
Seems to me a vented box is just a two-way when you break it apart. Like in hornresp, output 1 and output 2.
If the stored energy concept is real, seems to me it has to apply to all multi-way sections all the way down...
Plus I know, when you get truly flat mag and phase, waterfalls get perfect.
I think it all comes down to how do we make the low corner go low..... and with equal sensitivity to everything above
It's worth looking at the step response of various enclosure types and asking yourself how this might affect LF reproduction accuracy. Everyone (hopefully!) goes to great length of building stiff enclosures to minimise resonances, but imagine enclosure walls resonating for a couple of hundred milliseconds after the signal has stopped. This is what I am trying to get at my using the term 'stored energy'; something present in any resonant system which we need to minimise or dissipate very quickly to improve fidelity - low unsprung mass and shock absorbers (dampers), to use an automotive analogy. To my ear, employing a deliberately resonant speaker loading is not pleasing.
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Hi MrKinky, thanks for the reply.
I really don't think I can say anything about those two impulse responses without knowing more about how they were taken.
It almost looks from the action past the impulse peaks, that the GJALLERHORN doesn't have any kind of low pass filter in place, whereas the 18n862 sealed looks to maybe have one in place. Also I don't get all the gack in front of the GHorns peak. I'd need to go to Ricci's site and read up, to know what to think.
Also, I question comparing a tapped horn to a "vented vs sealed" discussion in terms of the idea of energy storage.
And must admit I'm not a fan of tapped horns, with their drivers butt hanging out playing the higher end, typically having to wait at least 8+ ms for the low end horn output to catch up.
I use the 18n862 in sealed, vented, and dual opposed configs. And yes, the impulse can't get any cleaner than sealed.
BTW, I really like all your sealed subs, in their tube like enclosures !!
Anyway, here is an impulse just taken of my latest sub, a double 18n862 vented, with the drivers facing each other at a right angle. I can it my "V-Twin" sub.
Indoors at about 4" from sub, right in between vent and drivers. Looks clean to me..you?
Like the stored energy in an MDF enclosure that oozes out the walls as time-delayed grunge.
dave
Define "clean". Any well-designed TH will have lower distortion than a sealed box with the same driver playing the same SPL.
It's also worth noting that the apparent ringing from the Gjallerhorn may well be outside of the intended passband. Do you know if processing was in place for these measurements, or is it the raw cabinet?
All we can say for sure is that the sealed box seems to be better behaved at higher frequencies. That shouldn't come as a surprise to anyone.
Chris