cred_audio wrote on Mon, 16 May 2005 06:47 |
One more question: Apart from maximum SPL, which of the two, LabSubs or Tuba36Slim will have a longer throw? Thanks |
Dave Gunness wrote on the EAW site |
A "long throw" speaker is normally considered to be a high-directivity speaker. Vertically, because it projects a tight beam, you're able to "throw" the sound over the heads of the nearest listeners without killing them with SPL. Horizontally, it sends less energy into the sidewalls of the room - so the reverb picks up more slowly as you walk toward the back. When it comes to floor-stacked subs, neither of these effects apply. All of the listeners are in the direct path of the subs, so there is no throwing it over their heads. Also, all subs have wide patterns, and nearly all rooms have relatively long reverb times at low frequencies - so the effect of low frequency directivity on the distribution of reverb in a room is usually insignificant. What is important is the area of the wavefront where it exits the box. In order to squeeze 100 acoustic Watts out of an 18-inch woofer, the sound pressure has to be extremely high at the surface of the woofer. If the same 100 acoustic Watts comes through a 3-foot by 3-foot horn mouth, the sound pressure will be much, much lower at the mouth (nearly 10 dB less). A hundred Watts is a hundred Watts, so at 50 feet, both systems will produce the same SPL. The difference then, is that for a given SPL at distance, the SPL down close to the speakers is much lower for the horn than it is for the direct radiator. That means the horn produces less SPL variation from near to far - than the direct radiator does. Some people would call that "throw". Incidentally, this form of "throw" works the same indoors as it does outdoors. David Gunness |
cred_audio wrote on Mon, 16 May 2005 03:47 |
8)I built the Tuba24; this morning I completed one box and loaded it with an HL10A driver. Tested with some music. It does not go deep |
bgavin wrote on Tue, 17 May 2005 12:35 |
The Tuba36 Slim at 7.5 feet....... |
Elliot Thompson wrote on Tue, 17 May 2005 05:00 |
Thats intresting. I assumed it was more than 7.5 feet. Thats .5 more of a Scoop. JBL's Scoop. Or are you refering to internal chamber the 15 sits in? |
bgavin wrote on Wed, 18 May 2005 01:53 |
7.5 feet is the horn length. I bought the plans to build (3) of the Tuba36 Slim, using 15" drivers I have on hand. Even then, (3) are only enough mouth area (half-space) for full loading to 55 Hz. The LAB are bigger 'n badder, no doubt about it. But I don't have need for that much Badness, nor response below 41 Hz. Portability is more of a concern for me, and even T36 Slims are a lot to move around. |
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The live sound RTA analysis puzzles me for a couple of reasons. The lack of bass program below 60 Hz could be from several causes: 1) Bass player doesn't play down low 2) Cabs don't produce much below 60 Hz 3) Power amp 50 Hz filters in place |
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Traditionally the path is measured down the center. You normally would start the measurement at the leading edge of the driver hole in plate 1. My estimate is about 8.5 feet, starting at the junctions of plate 1 and 2 to be conservative |
BHFProfessional wrote on Sun, 22 May 2005 00:28 |
My own experience with the Crusher project taught me what the HL10 likes and doesn't like. |
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The only theoretical advantage for the Lab is extension below 20 Hz and then only if at least 8 cabs are clustered to get the necessary mouth area. |
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I am only analyzing and relaying what I thought was common knowledge: The HL10 doesn't like oversized rear chambers |
kaisersoze wrote on Tue, 24 May 2005 09:26 |
snip ... Current thinking seems to reveal that although extension to the lower frequencies is desirable in live sound, a flat response to those frequencies is not absolutely necessary in real-world applications. |
Tom Danley wrote on Tue, 24 May 2005 14:39 |
Operating this at high levels significantly below 30 Hz (below the low cutoff on any box for that matter) is a mistake and I suppose a given in Pro sound that one uses a high pass filter for that reason. An exception would be when used in a room such as Brad Litz’s “home” system. |
Tom Danley wrote on Wed, 25 May 2005 01:09 | ||||||||||||
Hi Guys Also the LAB project was done for free by me and others, this is not Post by: Mark Seaton on May 25, 2005, 10:16:15 AM
Hi Brad, You might want to try taking some measurements and listening a bit without the hi-pass. In any confined room you will see a good deal of gain at low frequencies, where I would expect to see a shelved response to the low end of your system. The question is just how much maximum output you have down low from the combo of amps and subs. If sailing without a hi-pass is a bit too much, experiment with Bessel fitlers in your DSP as when set to 20Hz they will extend a little lower before the response drops more abruptly. Even this can be sculpted a bit with a shelf filter above the low cut-off. Obviously the above isn't a common practice for sound reinforcement, but the concept of being aware of output limitations and the corresponding requirements of your application are still quite important. In applications with lower output requirements you can certainly goose the low end quite a bit. At the same time, in some very high output or very large coverage applications you may end up high passing the system even above its nominal useful low end. In such cases, the decision has little to do with "unloading" but everything to do with helping the sub maintain composure under higher peak levels. In such cases, knowledge of the impedance curve can also be useful in understanding what you are asking from your amplifier. In the end realize that while it is certainly possible to determine levels and conditions at which a setup won't go into duress, but better understanding of the operation and capabilities will allow you to contour things appropriately for the application at hand while coming away with fewer component failures. Best Regards, Post by: John Chiara on May 25, 2005, 01:51:17 PM
I totally agree..and I believe this is what is usually missing from live sound reinforcement and what the future holds if enough of us can have our say. The lacking lower octave+ in most systems is what ..IMO...keeps the music from achieving the intimacy it could..if those lows are reproduced. I mix in the studio for my day job..with a sub flat below 20HZ..and far from being a "special effect" situation...it grows on you as a satisfying completeness that is sorely missed if removed. This is useful in mixing recordings but I believe even more so in reproducing live music in the 21st Century. Post by: Michael_Elliston¶ on May 25, 2005, 07:01:36 PM
No doubt It would be a good product,but wouldnt contain any patented fun goodies Post by: Timmahh on May 25, 2005, 07:31:19 PM more later. Post by: fernand on May 26, 2005, 07:05:14 AM
Interesting, could you tell us from your experience what sorts of energy you are seeing in the low spectrum ? Post by: John Chiara on May 26, 2005, 11:18:23 PM I totally agree..and I believe this is what is usually missing from live sound reinforcement and what the future holds if enough of us can have our say. The lacking lower octave+ in most systems is what ..IMO...keeps the music from achieving the intimacy it could..if those lows are reproduced. I mix in the studio for my day job..with a sub flat below 20HZ..and far from being a "special effect" situation...it grows on you as a satisfying completeness that is sorely missed if removed. This is useful in mixing recordings but I believe even more so in reproducing live music in the 21st Century. [/quote] Interesting, could you tell us from your experience what sorts of energy you are seeing in the low spectrum ?[/quote] First thing you find is all kinds of junk!!! It is..IMO.. necessary to run aux fed subs if at all possible....although with a real low frequency reproduction the overall sound is better than with a system with a big hump at 50-80hz. The main thing is that you get to hear the actual sound of many instruments that put out stuff in the 20-40hz area. In my experience having that extra octave makes it easier to balance kick and bass...frequency wise anyway..and even dynamically, having sufficient oomph down thaere feels very different from the boomy, muddy live venue sound we normally hear. The whole impression of "fidelity" changes..things sound cleaner, more open, more detailed..I think one reason is the extra low extension lets the fundamentals of lower instruments actually exist without being "cramped" by a restricted response. Synths tracks that actually sound full range are a different beast than what we are used to. I could go on subjectively but objectively I beleive that in practice "linear transfer"..meaning 'what goes in is what what comes out'..is at least approachable on the low freqency end...and I have not often..or ever..actually heard that in a live situation..but I do hear a whole bunch of other "crap" that seems to pass for low end..totally unnecesary with Labs, BassMaxx, BDeaps and Tom Danley's new sub models around. What needs to happen first is the pursuit of this as an ideal and then the tide can change. I am on board. Short term demos can help but I find a little "break in " time is often needed for the new response to become familiar enough to the conditioned brains of listeners to catagorize the resulting physical sensations as pleasant..but once it settles in there is no going back...PLUS one positive side effect is that listeners become comfortable with lower playback levels..a good thing for everyone..especially those of us working day after day at FOH. Post by: fernand on May 27, 2005, 01:28:01 AM could you tell us from your mixing experiences at what level the 20, 40, 60 , ... Hz signals are sitting in respect with the average signals ? Post by: Alan Searchwell on May 27, 2005, 06:09:39 AM Please consider your audience when you say things like: [quote title=BHFProfessional wrote on Sun, 22 May 2005 14:57] And I didn't have to blow up an expensive driver to learn that information (though I extend my condolences to anyone who did, as there are better and less costly ways of learning that info.) There are people on this board who have large multiples of the $135 cost of an Eminence HL-10 invested in their systems. For example $400+ would be considered a good deal on the Seismic 8196, Aura 1808 or McCauley 6174 that are used to load Bassmaxx cabinets (I think the list price is about twice that). Another example is the EAW SB1000 available at Music Center for $2,240. Not including labour, my prototype LAB cost me about $1000 complete with Rhino lining, 5 inch wheels and perforated metal grille but there are people who have had material cost them as little as $700. There are people on this board who have more than 8 LABs, heck I remember a guy in New Zealand saying he's planning to build 50! I plan to build four more and here in Jamaica that does not even qualify for entry into the real live sound market where I have seen 16+ SB1000 being used per side. Just think of how you must sound to some of these guys when you call a $135 speaker expensive! [quote title=BHFProfessional wrote on Tue, 24 May 2005 09:12] I also wanted to bring those concerns to your attention, after which I promptly had four or five people's feet broken off in my behind. Perhaps I wrote too authoritatively when I should have been phrasing more of the stuff as a question. Yes, perhaps you did and perhaps you "wrote too authoritatively" some time back when as I remember you saying that "person A" should do this and that and so forth to his design to achieve what you think will be better results meanwhile the "Crusher" remains on the drawing board. "Youth-full Exuberance" is the term that comes to mind. Tom Danley signs his posts "Tom Danley", Mark Seaton signs "Mark Seaton, Seaton Sound, Inc., Danley Sound Labs". In the case of Mark, both companies exist and and have some credibility. You on the other hand cite two imaginary "commercial ventures" which you proudly attach to your signature and then wonder why people stomp on you. Hmmm, are you trying to equate yourself to these gentlemen. It'll take quite a few years and some SOLID ACHIEVEMENTS to earn that kind of respect. The remarkable thing about the LAB Sub is that the lead designer is somebody with considerable experience who, has made and is likely to continue to make, a good living designing speakers. He has led the design of a product that approaches the performance of his own proprietary design (BT7) and made it available under a licence that protects him from commercial exploitation while allowing DIYers AROUND THE WORLD considerable leeway. Through this project DIYers have a subwoofer that can hold keep up with and even outperform commercially available touring class products that cost more than twice as much. Bill's designs, though quite remarkable in their own right cannot match all these criteria. There are people reading who have been lurking since the LAB Sub project was originally proposed back on "ye old Live Audio Board" who have only posted a fraction of the amount of times the exuberant Mr. Buszka has. Nonetheless it has been quite interesting although sometimes a tad irritating to read his posts. I suppose most of us have learned something. Carry on. Oh, and thanks again Tom! Post by: Michael_Elliston¶ on May 28, 2005, 11:19:21 PM I really dont see a problem with pursuing the bottom octave,or the top octave(that alot of HF horns miss)-but again it comes down to size,cost,transportation costs. Bottom octave!! http://www.speakerplans.com/forum/forum_posts.asp?TID=1525&a mp;PN=1 http://roborg.freefronthost.com/infra-horn.htm |