I've read the thread and have no idea what sort of positive quality of 'rumble' you are talking about. My first thought, since this involved PA/SR gear was signal input below the (port) tuning causing unnecessary excursion on the LF drivers. I ran PAs for many years and always high passed the LF system below tune, because I didn't want over excursion of the drivers, distortion and generally found that excessive LF caused more problems than it was worth, especially below 35-40Hz or so.
SPL for a given frequency is proportional to the volume of air moved, so for two drivers of the same Sd, the one with more excursion capability will be able to play louder. That doesn't mean it will do it cleanly though as that is a product of motor design mainly.
Let me define rumble as I am using it. When I attend different dances I listen for the quality of the sound system. When I am standing outside the room and around a corner I notice some systems have really appealing (to dance to) low frequency content or "Rumble" and other don't. At the time, I added a dbx® Subharmonic Synthesis Products (DBX Subharmonic Synth.) to my DJ system and pushed my Industrial LaSalla's hard and got a little of what I wanted.
What confuses me is people talking about low Fs 15's that have huge Xmax and low sensitivity for movie sound tracks. Could this be the answer and I just have to run lots of them to get the total spl I am after?
I guess my question is this, is this purely a function of low end extension and spl or some other system characteristic that I am unaware of and thus missing. (I am about to build a bunch of Bill Fitzmarice THT's (Tall version) to DJ with and need a gut check.)
You will get very little LF from FLH cabinets pushed below FC.
Hopefully, by "a bunch" you mean at least four.
The FLH will have lots of "gut feel", but not much down low, what you call "rumble".
Bill's hand drawn frequency response curves are the horns in a corner, not representative of the cabinet's response other than in a hand drawn corner.
The actual response is more like 10 dB down at 40 from 100 Hz, that is less than half as loud down low as in the "gut" range.
From a size standpoint, high Xmax drivers in ported cabinets will make more LF SPL than FLH, though it will take more drivers and power.
Nope, still tells me nothing. I have used (tried would be a better term) such sub synths before but didn't like them. However most of my work was with bands rather than recordings or TTs etc.
Given that the LS has a flare of about 125Hz and drops quickly below 100hz ading something to add extra LF blelow the flare rate is onlt causing a short Xmax driver to work very hard (at LF it's just a large driver in a small sealed box) to add a lot of harmonic components within the passband of the driver, an effect I would ordinarily avoid.
Most of these sort of drivers are not actually rated for continuous duty use so take the power rating with a grain of salt. If you did use them, I think you will be replacing drivers often and may not have warranty with them: the peak/average ratio and average power levels of almost all HT users is low compared to SR. It will also require lots of power.
SPL at a given frequency is proportional to the volume of air displaced, and all being even, each octave lower requires 4x the volume of air, hence why loud and low are usually not a part of most large SR systems. The logistics of getting below 40Hz loud becomes big and expensive, usually for no benefit and often with drawbacks such as LF noise spill to surrounding venues (local noise laws) and the extra LF finding every loose rattle inthe room.
Best of luck with that. The dearth of real measurements leaves me with no confidence there.
If you are doing THAT you need a minimum of four lab horns. (or 4 12-pi, or 4 Tuba 60). Anything less will result in blown woofers pushing any sort of real volume with a 120A. Especially trying to do it with some 50 Hz box. The corner frequency must be below the minimum frequency reproduced - which for a 120A, is 26 Hz.
I spent the better part of 20 years searching for "that sound" in a DJ system, and finally figured out you can't get there with typical cabs. That throbbing low end that you feel inside your head more than anything else - and continues to linger and rattle your bones long after the "kick" that any old system can produce. I started out with a "wall of 18's" in low tuned boxes - which almost gets there - but if you push the dB's it just distorts like an SOB and becomes unlistenable. Not to mention a reliability risk.
I got a good look at a system that was doing it - quite well in an open field. Four Basstech 7's driven by MA3600's and a 120A. The sticker shock was enough to make me give up audio altogether. Then Tom and his buds posted the plans to the LAB in '02... Only problem is it takes more than one trip to haul the big rig. Well, you either want the bass or you don't. I have smaller 40 Hz solutions when you don't.
There are exactly two ways to not push it below fc. One is easy, the other takes a bit more work.
Perhaps a reminder of what the term "sub" woofer originally refered to before a sub woofer became any speaker that smply reproduced audible frequencies that the inadiquate main speakers can not.
It originally was a speaker that reproduced the lower frequencies so low that they were mostly "sub" audible.
You could the feel the frequencies....... feel their "rumble" even though you could not hear really hear them all.
Perhap this is what the OP is refering to?
It originally was a speaker that reproduced the lower frequencies so low that they were mostly "sub" audible.
You could the feel the frequencies....... feel their "rumble" even though you could not hear really hear them all.
Perhap this is what the OP is refering to?
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120A = 120 Amp circuit?
FINALLY someone gets what I am trying to do. It's not PA and it's not Audiophile, it DJ!!!!!
I am not after blurred vision, although that sounds fun, just a more full bottom end sound. Yes you are right about the amps required. I am running 2400 watts into two 18's in a tuned box and it kinda does it. I don't think they go below 50hz and think that is my issue.
If I go with loaded horns I will get more spl and lower Fs. Maybe I should builds some labs or T60's?[/QUOTE]
120A = dbx 120A subharmonic synth. Or more correctly, the DSP emulation module built into the driverack 260.
I know exactly what you're trying to do. Before going much further, the surgeon general requires these warnings. 26 Hz capability isn't "required" to "reproduce music". 26 Hz-capable subs are "too large" to be "commercially viable". Lugging huge cabs around does not make sense from a "business model" perspective. The use of a dbx 120A for any sort of PA or public performance usage is strictly prohibited, punishable by being publicly flogged then skinned alive and hung. (The big boys with ten million dollar systems do it, but you're not allowed to.)
Now that we've got the warnings out of the way, it's time to go build some 26 Hz capable subs and get what you've been looking for. For a horn solution, the LABs, T60s, or Pi12's are all capable, with similar design goals. But all front loaded horns require a critical mass - which is about 32 square feet of mouth area to get that kind of low end. Otherwise, the response droops and each drum hit sounds like someone knocking on an empty wooden box because the response is so uneven. Less efficient conventional boxes could certainly be used, but low enough distortion drivers get stupid expensive fast and require a nuclear reaction to generate the 1.21 GW of electricity..... And cheaper ones require so many that you may as well build 4 horns. In any case, you won't be moving the rig with a Camry (or even a station wagon).
I know exactly what you're trying to do. Before going much further, the surgeon general requires these warnings. 26 Hz capability isn't "required" to "reproduce music". 26 Hz-capable subs are "too large" to be "commercially viable". Lugging huge cabs around does not make sense from a "business model" perspective. The use of a dbx 120A for any sort of PA or public performance usage is strictly prohibited, punishable by being publicly flogged then skinned alive and hung. (The big boys with ten million dollar systems do it, but you're not allowed to.)
Now that we've got the warnings out of the way, it's time to go build some 26 Hz capable subs and get what you've been looking for. For a horn solution, the LABs, T60s, or Pi12's are all capable, with similar design goals. But all front loaded horns require a critical mass - which is about 32 square feet of mouth area to get that kind of low end. Otherwise, the response droops and each drum hit sounds like someone knocking on an empty wooden box because the response is so uneven. Less efficient conventional boxes could certainly be used, but low enough distortion drivers get stupid expensive fast and require a nuclear reaction to generate the 1.21 GW of electricity..... And cheaper ones require so many that you may as well build 4 horns. In any case, you won't be moving the rig with a Camry (or even a station wagon).
As been said before, going the horn route requires a large mouth, a single Labsub or 12Pi won't cut it for low bass.
On the other hand, four dual Lab 12 in ported cabinets can fit in the same space as one of those bass horns. One or four, the ported cabinet still gets down to the low 30 Hz range.
FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems
I have run four of these side by side eight Meyers HP 650 dual 18 cabinets, and they put out more at 40 Hz than the eight 650Ps.
I have four of the dual Lab 12 ported cabinets for sale, PM if interested.
I went to an 18" tapped horn design, but the dual Lab 12s actually have a bit lower response, and are half the size.
Art Welter
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Thats what I am missing in my subs a FLUX Capacitor! 1.21 jigawatts!
I should have known!
Originally Posted by weltersys
As been said before, going the horn route requires a large mouth, a single Labsub or 12Pi won't cut it for low bass.
On the other hand, four dual Lab 12 in ported cabinets can fit in the same space as one of those bass horns. One or four, the ported cabinet still gets down to the low 30 Hz range.
FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems
I have run four of these side by side eight Meyers HP 650 dual 18 cabinets, and they put out more at 40 Hz than the eight 650Ps.
I have four of the dual Lab 12 ported cabinets for sale, PM if interested.
I went to an 18" tapped horn design, but the dual Lab 12s actually have a bit lower response, and are half the size.
Art Welter
Mike,
The Keystone sub:
http://www.diyaudio.com/forums/subwoofers/185588-keystone-sub-using-18-15-12-inch-speakers.html
Post #94 has plans, but the plans don’t include the bracing which can be seen in #63.
The bracing is needed.
Art
As been said before, going the horn route requires a large mouth, a single Labsub or 12Pi won't cut it for low bass.
On the other hand, four dual Lab 12 in ported cabinets can fit in the same space as one of those bass horns. One or four, the ported cabinet still gets down to the low 30 Hz range.
FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems
I have run four of these side by side eight Meyers HP 650 dual 18 cabinets, and they put out more at 40 Hz than the eight 650Ps.
I have four of the dual Lab 12 ported cabinets for sale, PM if interested.
I went to an 18" tapped horn design, but the dual Lab 12s actually have a bit lower response, and are half the size.
Art Welter
Mike,
The Keystone sub:
http://www.diyaudio.com/forums/subwoofers/185588-keystone-sub-using-18-15-12-inch-speakers.html
Post #94 has plans, but the plans don’t include the bracing which can be seen in #63.
The bracing is needed.
Art
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