I'm building a 12'' TH for outdoor use, and planning to use the Pioneer TS-W311D4 car sub,(TS-W311D4 Pioneer - Speakers, Subwoofers - Car*Entertainment) I got to thinking: Seeing as the driver with all the "fancy" plastic and stuff on the back of it is pretty big(16 cm deep), do I need to consider this in folding the horn? I mean how much will it impede airflow through the horn, and will I have to compensate for this?
Also on a sidenote, how does this sim look to you guys? I'm still pretty new with this horn stuff, but the design seems to give me the response I'm after(40-100ish hz). And do you trust the specs from Pioneer on this somewhat cheap driver?
Any comments on sim, design, choice of driver and favorite snack are very welcome!
Also on a sidenote, how does this sim look to you guys? I'm still pretty new with this horn stuff, but the design seems to give me the response I'm after(40-100ish hz). And do you trust the specs from Pioneer on this somewhat cheap driver?
Any comments on sim, design, choice of driver and favorite snack are very welcome!
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I am contemplating a SS15 with Infinity 1260w for a mini PA rig. Can't speak for the Pioneer but I've seen many success stories with the 1260w. That said, I share a similar concern with using a car sub. I cannot imagine the extra plastic will be a problem. Sim looks pretty good to me. I tried your sim with 1260w and was not an improvement. From what I've picked up, only the pro gear data can be trusted, even then, there are still variances. They way I see it, if we build these and fry the driver we're only out $60... It's all about intended use. My sub will be used along side of a 40w Behringer top so I really doubt I will push it. IOW I think the power ratings on car subs are highly suspect and would not push them beyond RMS.
With a 1.05 Qts, this driver isn't a viable TH option unless it's extremely large and then only if all that plastic cladding is removed.
Infinity, JBL, Alpine, MTX or similar mobile audio subs with a < 40 Hz Fs, 0.4 Qts is what you want.
GM
Infinity, JBL, Alpine, MTX or similar mobile audio subs with a < 40 Hz Fs, 0.4 Qts is what you want.
GM
Is this a better choice then?
http://www.ground-zero-audio.com/components/com_jshopping/files/demo_products/GZTW_30TX.pdf
It has Qts 0.53 instead of the 1.05 of the Pioneer. 30 sec in HR got me pretty much the same response as the Pioneer.
http://www.ground-zero-audio.com/components/com_jshopping/files/demo_products/GZTW_30TX.pdf
It has Qts 0.53 instead of the 1.05 of the Pioneer. 30 sec in HR got me pretty much the same response as the Pioneer.
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Well, unless you already have a good understanding of basic band-pass speaker design, then short of a lengthy tutorial I don't have time for, about the best I can think of is that one normally only design cabs to amplify a point source [cone/dome] driver's rising response portion of its BW = 2*Fs/Qts or ~81.9 Hz, i.e. not even one octave, so this ‘one note’ high Q alignment is theoretically only suited for peak SPL competitions and even then would be larger than typical since Qts dominates speaker cab design.
That said, one can obviously make grossly misaligned speakers and now with the advent of relatively inexpensive digital EQ one can [re]shape its response and some folks have done so with mixed results, so yours may/mayn’t perform as predicted and/or cause premature driver failure due to non-linear loading, especially when it’s a TH, and worse, when the driver is compression loaded like yours is [S2 is smaller than driver Sd].
As I noted though, one can properly horn load high Qt drivers if made large enough to offset its very weak motor, but why not spend all that extra $$$ in materials and maybe electronics towards a driver much more/best suited to the needs of the app? The only reason I can think of is if you live somewhere that has a very limited driver choice once shipping, etc., is factored in.
GM
It's a lot better, though still pretty far off the ideal, though of more importance is that any of these inexpensive driver's actual specs tend to be somewhat worse in reality, with Qts normally being somewhat, to grossly, higher since most of its manufacturing cost is in its motor assembly.
Best then to buy one of the drivers or at least brands such as the JBL GTO series or similar with proven results if it's an option.
GM
Seems like it would be an advantage to getting a super steep acoustic XO since he's only interested in a ~100 Hz top end.
GM
I'm looking at maybe getting the JBL GT4-12 instead then, since I can get two of them pretty cheaply(meaning two horns instead of one).
Specs are here http://www.team-bhp.com/forum/attac...read-before-posting-new-q-gt412_f1_page_1.jpg
They sim pretty nicely although I would the high corner higher, maybe 150 hz- this was a 30 sec sim though, I'll try to optimize it, if you guys agree with this choice of driver?
Specs are here http://www.team-bhp.com/forum/attac...read-before-posting-new-q-gt412_f1_page_1.jpg
They sim pretty nicely although I would the high corner higher, maybe 150 hz- this was a 30 sec sim though, I'll try to optimize it, if you guys agree with this choice of driver?
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I'm going to put this out there, I used a 2 SWS 12d4's in a dual TH and reached excursion/distortion limits about 3-4 dB below rated power. Keep in mind, when driving something outdoors or near it's limits that pro drivers cost more for a reason, they behave better and can handle better the outer reaches of their excursion for longer periods of time than car drivers. From my experience I'm not building any "pro" subwoofers (anything that will be used to 100%) using car drivers anymore.
Again, its HF response limit is defined by 2*Fs/Qts or ~107.5 Hz and shows up as a huge dip in your response that you can't get rid of.
Note too that typical TL/TH alignments are basically just ~two octaves due to its intrinsic 3rd harmonic dip, so tuning will need to be around 30.5 Hz, making the driver's Fs around 37.5 Hz and to keep it from being so under-damped, a <0.4 Qts is desired.
Attached is a GT12-4 2:1 CR [max recommended] TH text file to import with Fs, Qts changed to give you a 'frame of reference':
GM
Note too that typical TL/TH alignments are basically just ~two octaves due to its intrinsic 3rd harmonic dip, so tuning will need to be around 30.5 Hz, making the driver's Fs around 37.5 Hz and to keep it from being so under-damped, a <0.4 Qts is desired.
Attached is a GT12-4 2:1 CR [max recommended] TH text file to import with Fs, Qts changed to give you a 'frame of reference':
GM
Agree 100%, I took his 'mini' PA to mean for fairly casual affairs such as children, family or even block parties, which shouldn't need anywhere near the 115+ dB transient peaks the mobile audio drivers can handle for short periods.
GM
Yep; Family style pro bono gigs (IE graduation) where it's actually a knife fight. I do drag out a Keystone for block parties tho. 😀 That said, I am intimately familiar that such gigs do eventually get going a bit and there is a potential for failure if I push it. That's on me. It might be prudent to note that in my research on car subs in pro cabs I found a post that provided some interesting data. A pro audio engineer benched a well known 1,000 watt car audio power amp and found it to produce only 10% of the advertised specs... I expect a similar parallel with car drivers but I do give some credence towards reputable brands and particular drivers well reviewed such as the 1260w.
I need to measure and see if the the SS15 will be trunkable as many of these "gigs" will be not be local and I will be using the sedan and not the SUV. Might have to find another design with slimmer width or scale it down. I think 16" might be the widest. Heck, a good BR would probably be perfect but I am so enamored with TH designs. That dual 8" MCM TH that popped up from the deal is tempting...
I need to measure and see if the the SS15 will be trunkable as many of these "gigs" will be not be local and I will be using the sedan and not the SUV. Might have to find another design with slimmer width or scale it down. I think 16" might be the widest. Heck, a good BR would probably be perfect but I am so enamored with TH designs. That dual 8" MCM TH that popped up from the deal is tempting...
Under powering a speaker is a recipe for disaster, so the amp's voltage rails rating should be at least double the driver's program rating and preferably 4x and if this spec isn't available, then 'caveat emptor'.
Yeah, too many of the mobile audio woofer offerings have either bogus peak ratings or publish its highest transient burst failure, so figure it's maybe capable of 1.5-2x its program rating for peak dynamic headroom, which means that depending on how much headroom your program material has you may need to either limit it or reduce continuous max power SPL expectations.
With cheap[er] amps and/or 'subs', it's a good plan to wire a 'clipping' light bulb in series to have a visual fused disconnect.
GM
edit: haven't read it, but recall having answering some of Wayne's and other's Qs on another forum way back when me and a few others were recommending upgrading plate, HIFI amps to prosound for 'sub' systems, so may be of some help with fine tuning your system: http://www.hometheatershack.com/for...ing-most-pro-audio-equipment-your-system.html
Yeah, too many of the mobile audio woofer offerings have either bogus peak ratings or publish its highest transient burst failure, so figure it's maybe capable of 1.5-2x its program rating for peak dynamic headroom, which means that depending on how much headroom your program material has you may need to either limit it or reduce continuous max power SPL expectations.
With cheap[er] amps and/or 'subs', it's a good plan to wire a 'clipping' light bulb in series to have a visual fused disconnect.
GM
edit: haven't read it, but recall having answering some of Wayne's and other's Qs on another forum way back when me and a few others were recommending upgrading plate, HIFI amps to prosound for 'sub' systems, so may be of some help with fine tuning your system: http://www.hometheatershack.com/for...ing-most-pro-audio-equipment-your-system.html
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Basically (ha ha), Q is a measure of how well the speakers' motion is controlled.
The mass of the cone stiffness of the suspension + box affect the Q by determining how sharply resonant the system is. It's like a weight hanging on a spring, or the springs holding up the weight of a car.
Then the magnet/coil system try to control that. Imagine shaking a bowling ball back and forth. Who could do that more easily? Gilligan, or Dwayne "The Rock" Johnson? Doh, Dwayne, because he's stronger. That's kind of the relation between the cone/coil mass and the magnet/coil strength. The stronger the magnet/coil system, the better it can control the cone motion back and forth.
A Q of 1.03 indicates this motor system cannot control the cone motion very well. So pretty much no matter what kind of box you put it in, this woofer will not stop after the musical signal does, it will continue to "ring" for some time afterwards = muddy bass.
As a loudspeaker engineer, I concur you want something with a much lower Q to build a successful, tight sounding speaker.
The mass of the cone stiffness of the suspension + box affect the Q by determining how sharply resonant the system is. It's like a weight hanging on a spring, or the springs holding up the weight of a car.
Then the magnet/coil system try to control that. Imagine shaking a bowling ball back and forth. Who could do that more easily? Gilligan, or Dwayne "The Rock" Johnson? Doh, Dwayne, because he's stronger. That's kind of the relation between the cone/coil mass and the magnet/coil strength. The stronger the magnet/coil system, the better it can control the cone motion back and forth.
A Q of 1.03 indicates this motor system cannot control the cone motion very well. So pretty much no matter what kind of box you put it in, this woofer will not stop after the musical signal does, it will continue to "ring" for some time afterwards = muddy bass.
As a loudspeaker engineer, I concur you want something with a much lower Q to build a successful, tight sounding speaker.
Theoretically this isn't true and some years ago posted a reactance annulled parabolic BLH with a calculated 0.4-0.5 Qt [can't remember exactly] using a 2.45 Qts driver, but currently don't have access to the link or the software to recalculate/sim it, though anyone who knows how to manipulate Prof. Leach's horn design routine can do it.
Not that it's a practical alignment for almost all apps since any really high Qt driver will make it a large, narrow BW alignment, just that at least in theory one can acoustically critically damp even a ridiculously under-damped driver and since an OB is the acoustical reciprocal of such a horn, up to the point where the baffle has shrunk to being just the driver, it too will lower its system Q [sysQ], though not as much of course.
Carver's 'Amazing Loudspeaker' has a sub array using an even higher Qt woofer to get a high enough efficiency on a narrow OB with an acceptable sysQ: Carver Amazing Loudspeaker (Platinum Edition) | Stereophile.com
GM
Oh wow, hadn't thought about reactance annulling in a looooong time. I'm not sure how well it works in real life-this thread
http://www.diyaudio.com/forums/multi-way/221326-tune-rear-chamber-reactance-annulling.html
goes on more about it if the OP wants to look.
As for the Q, and "Theoretically this isn't true" maybe I should reconsider the description I used. When I said "A Q of 1.03 indicates this motor system cannot control the cone motion very well" I meant the driver as used in an enclosure (and not really thinking about horn enclosures necessesarily). In the case of Carver and others, the Q is not raised by the box since there is no box, and a total Q of 1 doesn't ring so much, and probably not too noticeable if the resonance is at a low frequency.
By the way, I suppose you could use a negative output impedance amplifier-though as with all electronic solutions (expect maybe a servo), the compensation is probably not really valid over most of the operating conditions of the speaker.
Works great when properly done, but few folks are willing to build full size [mid]bass horns or use a parabolic flare for mids-up apps, though you can get close with an expo.
Yeah, I just wanted to clarify/expand on what you posted. To expand on OBs, its sysQ can be < the driver's Qts, with the Carvers being an extreme example.
Yeah, it can also be done electronically with a Linkwitz Transform, but I prefer acoustic solutions for acoustic problems whenever it's practical to keep efficiency high as practical.
GM
Yeah, I just wanted to clarify/expand on what you posted. To expand on OBs, its sysQ can be < the driver's Qts, with the Carvers being an extreme example.
Yeah, it can also be done electronically with a Linkwitz Transform, but I prefer acoustic solutions for acoustic problems whenever it's practical to keep efficiency high as practical.
GM
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