Home |
Search |
Today's Posts |
#1
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
I want to build a new enclosure, and do it right. So...
- Does it matter which face of the enclosure the drivers and ports are on? On my current box, the ports are on the opposite face as the drivers. An installer here says the drivers and ports should go on the same face, which I'd rather do if there's no reason not to. - For a 12w3v2-d2, JL 'recommends' a 1.75 cu ft box, with a 4" port that's 15.25" long. I've been playing with WinISD, and I can get freq. response as low as I want my making the box bigger and bigger. A JL techy says I can make the box slightly larger to make up for some of the driver displacement and port volume, but not to make it make it larger than 1.85 or 1.9. They say they build and test boxes, and 1.75 IS optimal. The JL techy and the installer I talk to, neither of em heard of WinISD, and neither trust any of 'those goofy box programs on the internet'. The installer said he'd build it 1.75 GROSS volume. ..75" MDF is fine, right? I was planning on 1", but home depot and Menards only sell .75. I assume that's ok, since that's what my existing box is. Anything better to use? TIA, |
#2
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
First, 3/4-inch MDF is great material.
Now - the bigger the box, the lower fequency response you can get, THEORETICALLY. It doesn't always turn out so well. I once made a box that had one Jensen 10-inch sub in just over 3 cubic feet (ported, of coarse, and tuned to 26 Hz using WinISD). The specs on the sub said it could handle 175 watts rms, and I had it hooked up to a JBL amp that said it put out 150 watts rms. What happened? I blew that sub within a month. It would seem that I had pushed the sub beyond it's specified limits, and/or the sub was slightly overrated, and/or the amp was slightly underrated. Personally, I believe it was a combination of the three reasons. However, I currently have a box that drive 1 10-inch JBL woofer with a volume (after taking out port and driver volume) of nearly 2.5 cubic feet with NO PROBLEMS whatsoever. In this case, it's a higher quality sub rated for WELL over what the amp is rated (sub is capable of 250 watts rms, same amplifier), and I didn't try to stretch the hell out of the subs specs (subs resonant frequency [Fs] is 26 Hz, and this box is tuned to that number almost exactly). Remember that WinISD is not perfect; it is simply a good guide. Do not try to stretch the limits of your woofer too much - if you go too far you'll often ruin your sub. All that being said, nearly two cubic feet for one 12-inch sub of, presumably, high power and quality (which, I hear JL Audio is both) is MORE than enough in my experience. I would venture an educated guess that the box you described would be tuned to somewhere around 23 - 25 Hz - which is lower than most people would need. What frequency are you trying to get down to? ~The Lull mfreak wrote: I want to build a new enclosure, and do it right. So... - Does it matter which face of the enclosure the drivers and ports are on? On my current box, the ports are on the opposite face as the drivers. An installer here says the drivers and ports should go on the same face, which I'd rather do if there's no reason not to. - For a 12w3v2-d2, JL 'recommends' a 1.75 cu ft box, with a 4" port that's 15.25" long. I've been playing with WinISD, and I can get freq. response as low as I want my making the box bigger and bigger. A JL techy says I can make the box slightly larger to make up for some of the driver displacement and port volume, but not to make it make it larger than 1.85 or 1.9. They say they build and test boxes, and 1.75 IS optimal. The JL techy and the installer I talk to, neither of em heard of WinISD, and neither trust any of 'those goofy box programs on the internet'. The installer said he'd build it 1.75 GROSS volume. .75" MDF is fine, right? I was planning on 1", but home depot and Menards only sell .75. I assume that's ok, since that's what my existing box is. Anything better to use? TIA, |
#3
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Oops, almost forgot about port position.
There are a couple of important things to think about when deciding which way your ports are going to face. First, you're tuning your box to a certain frequency when you're porting it. Say you tune the box to 23 Hz, like I assumed before. As I understand it (damn, I love having to dodge you flamers), the notes/frequencies closest to 23 Hz (in this case) come out of the ports more than the actual subwoofer. It's not super-important, but it's something I always keep in the back of my mind. Next, for a simple ported design, the ports and the sub should ALWAYS share the same airspace - unless you are making some sort of bandpass enclosure. This doesn't mean that the ports HAVE to be on the same side/surface of the box as the sub, but that's usually the easiest way to ensure that this is the case. I have had good luck in making a box where the sub fires upward, and the ports face the rear of the vehicle. I have had excellend luck with the sub and ports all on the same side of the box. But if you were going to, say, create a wall where your box is seperate from the rest of your trunk - then it would not be the best practice to have the sub firing up and the ports leading to the trunk side of that wall. Big Disclaimer: The above posts are pulled directly from personal experience and knowledge I've gained from question asked, FAQs read, and other crap in this group. If something I said is *technically* wrong - please correct me, but for the love of god try to be civil about it. ~The Lull mfreak wrote: I want to build a new enclosure, and do it right. So... - Does it matter which face of the enclosure the drivers and ports are on? On my current box, the ports are on the opposite face as the drivers. An installer here says the drivers and ports should go on the same face, which I'd rather do if there's no reason not to. - For a 12w3v2-d2, JL 'recommends' a 1.75 cu ft box, with a 4" port that's 15.25" long. I've been playing with WinISD, and I can get freq. response as low as I want my making the box bigger and bigger. A JL techy says I can make the box slightly larger to make up for some of the driver displacement and port volume, but not to make it make it larger than 1.85 or 1.9. They say they build and test boxes, and 1.75 IS optimal. The JL techy and the installer I talk to, neither of em heard of WinISD, and neither trust any of 'those goofy box programs on the internet'. The installer said he'd build it 1.75 GROSS volume. .75" MDF is fine, right? I was planning on 1", but home depot and Menards only sell .75. I assume that's ok, since that's what my existing box is. Anything better to use? TIA, |
#4
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
On Oct 18, 11:30 am, "mfreak" wrote:
- Does it matter which face of the enclosure the drivers and ports are on? On my current box, the ports are on the opposite face as the drivers. An installer here says the drivers and ports should go on the same face, which I'd rather do if there's no reason not to. I concur with your installer. By placing the ports and drivers on different sides of the box, you open yourself up to phase issues that may or may not lead to audible problems. Remember...those ports aren't just there to let the subwoofer "breathe"--sound comes out of them, too, so you want to have them on the same surface as the driver whenever possible. - For a 12w3v2-d2, JL 'recommends' a 1.75 cu ft box, with a 4" port that's 15.25" long. I've been playing with WinISD, and I can get freq. response as low as I want my making the box bigger and bigger. A JL techy says I can make the box slightly larger to make up for some of the driver displacement and port volume, but not to make it make it larger than 1.85 or 1.9. They say they build and test boxes, and 1.75 IS optimal. The JL techy and the installer I talk to, neither of em heard of WinISD, and neither trust any of 'those goofy box programs on the internet'. The installer said he'd build it 1.75 GROSS volume. Do *exactly* what the JL techs tell you. I can assure you that the recommendations and instructions they give you are for your own benefit. JL doesn't just put arbitrary box specs together and say "Hey, let's just tell people to do this because we don't have time to sit around and test all this junk." And especially when dealing with ported boxes, don't add "just a little" to compensate for the displacement of the driver and the port. JL Audio provides exact displacement specs measured in cu. ft. for every single one of their subwoofers (0.07 cu. ft. in your specifc case: http://mobile.jlaudio.com/products_s...es_id=12)--use them. Also, do a little math and figure out what the exact displacement of your ports and bracing is going to be and take that into consideration when building your box. As far as trusting "those goofy box programs", there's some truth to that. Modeling the precise behavior of a loudspeaker isn't very easy. You can get a decent idea of whether you're in the ballpark with "goofy box programs", but ultimately a machine absolutely cannot tell you how good something is going to sound (or how it's going to behave under power)--you can have two plots that look very similar and have one sound like dog meat. Additionally, unless you have received some technical training on how to use modeling programs and unless you have a good understanding of the trade-offs involved in design decisions, you could very well set yourself up for failure. Simply making a box bigger and bigger to get "whatever frequency response I want" is not a valid way to design subwoofer enclosures. Lastly, modeling programs cannot tell you what the driver is going to sound like in the car. Remember that a vehicle's "transfer function" will add a roughly 12dB SPL/octave boost starting at the frequency whose wavelength is half of your vehicle's interior length. For example, a car with an interior length of 12 feet would beging to boost frequencies below about 47Hz (a 47Hz wave is about 24 feet long at sea level), so that if your sealed-box's f3 were at 47Hz, you'd theoretically get a nearly flat response curve below that point. This is why subs always sound more "meaty" in a car than they do in a home--the acoustics of the vehicle play a huge role in the overall response of your system. If you approach your design with the mistaken notion that "the lower the f3 is, the better my bass will sound", you're going to be in for a rude awakening when you fire-up the system. A super-low f3 in a vehicle can result in really awful-sounding, imbalanced, over-powering bass that your midrange drivers will almost certainly not be able to keep up with. .75" MDF is fine, right? I was planning on 1", but home depot and Menards only sell .75. I assume that's ok, since that's what my existing box is. Anything better to use? 3/4" is fine for most applications. Make sure you brace the box very well--rigidity is key. You would do well to read the JL Audio box-building tutorials: http://mobile.jlaudio.com/support_pages.php?page_id=141 -dan |
#5
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
In article . com, "The Lull" wrote:
Oops, almost forgot about port position. There are a couple of important things to think about when deciding which way your ports are going to face. First, you're tuning your box to a certain frequency when you're porting it. Say you tune the box to 23 Hz, like I assumed before. As I understand it (damn, I love having to dodge you flamers), the notes/frequencies closest to 23 Hz (in this case) come out of the ports more than the actual subwoofer. It's not super-important, but it's something I always keep in the back of my mind. Gee, I still use a DOS program for all my stuff. Q-box. The port at 23 hz will have vertually all the sounds, so yes, the position can make a difference in relation to the vehicle. I would normally like to have the ports as far back and as close to a rear surface as possible. greg |
#6
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
D.Kreft wrote: Do *exactly* what the JL techs tell you. I can assure you that the recommendations and instructions they give you are for your own benefit. JL doesn't just put arbitrary box specs together and say "Hey, let's just tell people to do this because we don't have time to sit around and test all this junk." Thanks for the links, that's very helpful. I will go with the recommendation. I thought maybe they give you an optimal *practical* enclosure. Ie, if bigger is better, then optimal would be a box that exactly fits your trunk, but make it 1.75 cuz after that the gain is minimal for the extra volume.. OR something along those lines. I'll do the math and calculate volumes of ports, driver, bracing, everything and make the box's volume exactly 1.75. |
#7
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
The Lull wrote:
First, you're tuning your box to a certain frequency when you're porting it. Say you tune the box to 23 Hz, like I assumed before. As I understand it (damn, I love having to dodge you flamers), the notes/frequencies closest to 23 Hz (in this case) come out of the ports more than the actual subwoofer. It's not super-important, but it's something I always keep in the back of my mind. Thanks Lull, in fact your huge box and extremely low tuning is what made me consider making a bigger-than-recommended box in the first place. JL says the box they recommend is tuned to 30.8 Hz (WinISD says 32.56 with the volume/port size), with an F3 right around 32Hz. My installer says 31 Hz is really damn low, and I was thinking 'meh.. lull is 26 with a 10' The box I have now is not even close to recommendation, so I'm sure it'll be a huge improvement. I'm no acoustic engineer or anything, so I'll trust the JL guys know what they're talking about and build to their specs. |
#8
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Oh, and one more thing before I forget: If the ports coming out the
front face, and they're 15.25" long, then they'll be really close to the back face of the box on the inside of the box. I'm sure there's some minimum clearance on the inside of the box? If it was 1/8" from the back, then it's just about not a port at all, it's just taking up volume correct? I'm thinking 3 or 4 inches, or do i need more? Thanks again, |
#9
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
3 inches would be more than adaquate, but I'm not certain there's a
hard and fast rule on this (are you beginning to see the gigantic gray area that is sub box design?). ~The Lull mfreak wrote: Oh, and one more thing before I forget: If the ports coming out the front face, and they're 15.25" long, then they'll be really close to the back face of the box on the inside of the box. I'm sure there's some minimum clearance on the inside of the box? If it was 1/8" from the back, then it's just about not a port at all, it's just taking up volume correct? I'm thinking 3 or 4 inches, or do i need more? Thanks again, |
#10
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Um, I'm curious...
On your Thiele-Small parameters for the sub, what's the Fs? I would've thought that a 12-inch JL sub would be in the 20's somewhere. Someone (politely) tell me if I'm wrong, but I would NEVER create a ported box where the tuned frequency is HIGHER than the resonant frequency of the sub........ ~The Lull mfreak wrote: The Lull wrote: First, you're tuning your box to a certain frequency when you're porting it. Say you tune the box to 23 Hz, like I assumed before. As I understand it (damn, I love having to dodge you flamers), the notes/frequencies closest to 23 Hz (in this case) come out of the ports more than the actual subwoofer. It's not super-important, but it's something I always keep in the back of my mind. Thanks Lull, in fact your huge box and extremely low tuning is what made me consider making a bigger-than-recommended box in the first place. JL says the box they recommend is tuned to 30.8 Hz (WinISD says 32.56 with the volume/port size), with an F3 right around 32Hz. My installer says 31 Hz is really damn low, and I was thinking 'meh.. lull is 26 with a 10' The box I have now is not even close to recommendation, so I'm sure it'll be a huge improvement. I'm no acoustic engineer or anything, so I'll trust the JL guys know what they're talking about and build to their specs. |
#11
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Who in there right mind would tune a port down to 23hz and why??
|
#12
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
The Lull wrote:
On your Thiele-Small parameters for the sub, what's the Fs? According to JL at http://mobile.jlaudio.com/products_s...p?series_id=12 the Fs is 24.3 Hz. I would've thought that a 12-inch JL sub would be in the 20's somewhere. In the owners manual for that particular sub - http://mobile.jlaudio.com/pdfs/8681.pdf the recommended slot ported box is 30.8 Hz. I phoned JL tech support, they said to go with 1.75 cu ft, with a round port that's 4" in diameter and 15.25" long. I assume this would be the equivalent 30.8 Hz, WinISD reports it's 32.5 or 32.6, I forget and don't have it in front of me now. Someone (politely) tell me if I'm wrong, but I would NEVER create a ported box where the tuned frequency is HIGHER than the resonant frequency of the sub........ Assuming the given data is correct, JL apparently would, but IDK why.. Of course IDK why you don't like that idea, cuz IDK anything about box design... I am a good carpenter tho, given the dimensions I can build it.. That's all I DO know, |
#13
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Captain_Howdy wrote:
Who in there right mind would tune a port down to 23hz and why?? What kind of stupid question is this? -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#14
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
On Oct 18, 1:53 pm, "mfreak" wrote:
Oh, and one more thing before I forget: If the ports coming out the front face, and they're 15.25" long, then they'll be really close to the back face of the box on the inside of the box. I'm sure there's some minimum clearance on the inside of the box? If it was 1/8" from the back, then it's just about not a port at all, it's just taking up volume correct? I'm thinking 3 or 4 inches, or do i need more? Thanks again, Read the JL tutorial on box design...there's a section (or a complete tutorial) on how to do slot (rectangular) ports. JL Audio also used to sell some stuff called "FlexPort" which is a flexible (yet rigid) port material. I don't know if they still offer it, though--check their site. Generally speaking, you want to keep the end of the port 1 effective diameter away from any orthogonal wall...the more distance the better, though. -dan |
#15
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
What part did you not understand?
In article , (Eric Desrochers) wrote: Captain_Howdy wrote: Who in there right mind would tune a port down to 23hz and why?? What kind of stupid question is this? |
#16
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
One of the sections within that JBL informational website link posted
above (http://mobile.jlaudio.com/support_pa...p?page_id=150), gives a much better explanation of why one wouldn't design a ported box tuned to a frequency above the Fs of a sub (a bit of a long read, but pay attention to the last part): [Quote from http://mobile.jlaudio.com/support_pa...p?page_id=150] In a ported enclosure, there is a delicate relationship between the volume of air in the box, the resonant effect of the port, and the parameters of the speaker being used. When these three factors are correctly integrated, the rear output wave of the speaker is delayed just enough so that when it comes out of the port, it is in relative phase with the wave being produced by the front of the speaker. The result is constructive output from the port limited to a desired low- frequency range. This low-frequency reinforcement is one of the big advantages of a well-designed ported system. Using the work of the rear of the cone in a constructive manner means that a gain in efficiency of about 3dB over a broad band in the sub-bass range can be achieved as compared to a sealed enclosure using the same woofer. The other big advantage is that the interaction of the port, the enclosure and the speaker's resonant characteristics also reduces cone motion and, therefore, distortion at higher volume levels in the frequency range controlled by the port. The down side is that at frequencies below the tuning of the port, the speaker gradually begins to act as if it were not enclosed at all... [/Quote from http://mobile.jlaudio.com/support_pa...p?page_id=150] Here's what that last sentence means to me: If your sub ITSELF can/will produce frequencies of 24.3 (as you stated), then your sub will act as though it is not enclosed at all at those frequencies which, according to all I've been told, is bad. I'm not saying that JL doesn't know what they're talking about - I'm saying I'm a little confused since they seem to have some contradiction going on here.... ~The Lull P.S. Howdy - As I'm sure you're aware, there is music out there that utilizes extremely low frequencies (techno, big beat, electronic). I have no idea what mfreak listens to, but let's pretend for a moment that he's not you. Let's also pretend that perhaps he listens to a LOT of music that hits these super low notes. It might be perfectly valid to tune a ported box to 23 Hz in that case, wouldn't it? So to answer your question - some people, and for certain types of music. Probably 23 Hz isn't necessary, true. But that was a guess on my part, and evidently not what mfreak is going for. Therefore yours is not a relevant question. mfreak wrote: The Lull wrote: On your Thiele-Small parameters for the sub, what's the Fs? According to JL at http://mobile.jlaudio.com/products_s...p?series_id=12 the Fs is 24.3 Hz. I would've thought that a 12-inch JL sub would be in the 20's somewhere. In the owners manual for that particular sub - http://mobile.jlaudio.com/pdfs/8681.pdf the recommended slot ported box is 30.8 Hz. I phoned JL tech support, they said to go with 1.75 cu ft, with a round port that's 4" in diameter and 15.25" long. I assume this would be the equivalent 30.8 Hz, WinISD reports it's 32.5 or 32.6, I forget and don't have it in front of me now. Someone (politely) tell me if I'm wrong, but I would NEVER create a ported box where the tuned frequency is HIGHER than the resonant frequency of the sub........ Assuming the given data is correct, JL apparently would, but IDK why.. Of course IDK why you don't like that idea, cuz IDK anything about box design... I am a good carpenter tho, given the dimensions I can build it.. That's all I DO know, |
#17
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
In article .com, "The Lull" wrote:
One of the sections within that JBL informational website link posted above (http://mobile.jlaudio.com/support_pa...p?page_id=150), gives a much better explanation of why one wouldn't design a ported box tuned to a frequency above the Fs of a sub (a bit of a long read, but pay attention to the last part): [Quote from http://mobile.jlaudio.com/support_pa...p?page_id=150] In a ported enclosure, there is a delicate relationship between the volume of air in the box, the resonant effect of the port, and the parameters of the speaker being used. When these three factors are correctly integrated, the rear output wave of the speaker is delayed just enough so that when it comes out of the port, it is in relative phase with the wave being produced by the front of the speaker. The result is constructive output from the port limited to a desired low- frequency range. This low-frequency reinforcement is one of the big advantages of a well-designed ported system. Using the work of the rear of the cone in a constructive manner means that a gain in efficiency of about 3dB over a broad band in the sub-bass range can be achieved as compared to a sealed enclosure using the same woofer. The other big advantage is that the interaction of the port, the enclosure and the speaker's resonant characteristics also reduces cone motion and, therefore, distortion at higher volume levels in the frequency range controlled by the port. The down side is that at frequencies below the tuning of the port, the speaker gradually begins to act as if it were not enclosed at all... Its a little confusing or misleading about the exact things that are happening. The port and driver have a phase mismatch at the point where each is contributing. Below this vertually all comes from the port, and the same for the upper range, the driver has most all the output. Ported boxes don't gain efficiency, they gain bandpass. The efficiency is set by the driver alone. Drivers that work well in ported boxes generall have higher efficiency than an equivalant driver designed for sealed box. I don't hear much talk about ported box types around here. It was drummed into me from way back There are ways to describe th eeffects of various port tunning box size. May I quote from the Loudspeak Handbook I'm sure if discriptions were included in the book, but things like boom, or transient response, usually are described with each configuration. There are at least 15 well-established alignment categories, such as SSB4 ~Super Fourth-Order Boom Box!, SC4 ~Fourth Order Sub-Chebychev!, QB3 ~Quasi Third-Order alignment!, and discrete alignments such as the Fourth-Order Butterworth ~B4!, Fourth-Order Bessel ~BE4!, and Butterworth Inter-Order ~IB4!. greg [/Quote from http://mobile.jlaudio.com/support_pa...p?page_id=150] Here's what that last sentence means to me: If your sub ITSELF can/will produce frequencies of 24.3 (as you stated), then your sub will act as though it is not enclosed at all at those frequencies which, according to all I've been told, is bad. I'm not saying that JL doesn't know what they're talking about - I'm saying I'm a little confused since they seem to have some contradiction going on here.... Sometime a good high pass filter is recommended above the box tunning, to preven excessive excursion and increase power handling. ~The Lull P.S. Howdy - As I'm sure you're aware, there is music out there that utilizes extremely low frequencies (techno, big beat, electronic). I have no idea what mfreak listens to, but let's pretend for a moment that he's not you. Let's also pretend that perhaps he listens to a LOT of music that hits these super low notes. It might be perfectly valid to tune a ported box to 23 Hz in that case, wouldn't it? So to answer your question - some people, and for certain types of music. Probably 23 Hz isn't necessary, true. But that was a guess on my part, and evidently not what mfreak is going for. Therefore yours is not a relevant question. mfreak wrote: The Lull wrote: On your Thiele-Small parameters for the sub, what's the Fs? According to JL at http://mobile.jlaudio.com/products_s...p?series_id=12 the Fs is 24.3 Hz. I would've thought that a 12-inch JL sub would be in the 20's somewhere. In the owners manual for that particular sub - http://mobile.jlaudio.com/pdfs/8681.pdf the recommended slot ported box is 30.8 Hz. I phoned JL tech support, they said to go with 1.75 cu ft, with a round port that's 4" in diameter and 15.25" long. I assume this would be the equivalent 30.8 Hz, WinISD reports it's 32.5 or 32.6, I forget and don't have it in front of me now. Someone (politely) tell me if I'm wrong, but I would NEVER create a ported box where the tuned frequency is HIGHER than the resonant frequency of the sub........ Assuming the given data is correct, JL apparently would, but IDK why.. Of course IDK why you don't like that idea, cuz IDK anything about box design... I am a good carpenter tho, given the dimensions I can build it.. That's all I DO know, |
#18
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
On Oct 18, 2:36 pm, "The Lull" wrote:
Someone (politely) tell me if I'm wrong, but I would NEVER create a ported box where the tuned frequency is HIGHER than the resonant frequency of the sub........ I can't comment on this directly because I'm so rusty at this, but what I can say is that it's never a good idea to consider just *one* of the T/S parameters and make judgement calls about the performance of the driver in an enclosure or how you'd tune it. Unfortunately, the individual T/S parameters are not orthoganal to one another--it's kinda like flying a helicopter--if you alter the main rotor speed, you have to also fiddle wtih your pedals, or you'll start spinning like a top....very tricky (unless the helicopter is one of them new-fangled ones that handle all these adjustments for you by one of them computer things). -dan |
#19
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
it. Unfortunately, the individual T/S parameters are not orthoganal to
one another ORTHOGANAL - Cool word!!! I had to look that one up. MOSFET |
#20
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Captain_Howdy wrote:
What part did you not understand? In article , (Eric Desrochers) wrote: Captain_Howdy wrote: Who in there right mind would tune a port down to 23hz and why?? What kind of stupid question is this? Fine formulas were put toghether more than 30 years ago. You take the driver's T/S parameters, put them into said formulas and the ideal box volume and port tuning are calculated for you. If the port turn out to be tuned at 23, 20 or even 14 Hz, so be it. THIS IS THE CORRECT WAY to determine a box tuning, if sound quality is your goal. 45 Hz one-note-wonder are another story. I guess my question would be what do you find to be wrong with a 23 Hz box? -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#22
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Captain_Howdy wrote:
There is very little music out there in the 23hz range. If you want a full range system, you'll want to reproduce it anyway. The lowest tone in non electronic instrument is the A1 note on a Piano 28hz. Yeah, but we are surrounded by electronic music all day long. Please download "I miss you (Photek remix) by Bjork, for thremendous amount of content in the 25-30 Hz range. Also, some big organ have 32 feet pipes, producing a note of 16 Hz. Such music was indeed recorded. That you can hear it is irrelevant, you can feel it. Music has it's heaviest bass content in the 35-65hz range. Most of the time, yes, but exceptions are becoming the norm now. You'll even notice that most speaker manufactures recommend port tuning frequencies of 33-40hz and a subsonic filter setting between 25-30hz. What drivers and what manufacturer. I'll give you a different example. The 12" Dayton Titanic, a popular DIY sub, when ported, needs a 3.71 cubic-feet, a Fb of 19.52 Hz, for an F3 of 18.22 Hz. This is my definition of a full range sub. It give a box kinda big for a car but should do wonder in a home system. Now, I know about cabin gain and why such a deep response is not desirable in a car. I was just arguing about the "absolute silliness of 23 Hz box" in general. Never say never, as they say... What makes you think that a 45hz port tuning will give you a one-note-wonder is beyond me, I'm not saying a 45 Hz tuning is bad. I'm saying that a driver who would need, say 28 Hz, but you decide to tune it to 45 Hz anyway would probably be very loud but will sound like ****. A lot of the boom box on wheels you hear are overbearing at 45 Hz with not much below 35 Hz. That's where the expression come. I'm sure you have heard it before? To each its own I guess... -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#23
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
I personally tuned my ports to 36hz, found it to be a good area for lows and
SPL. It's sounds wild with anything that I throw at it, even with a 25hz subsonic filter. Yet it still slams 151.6db on a term-lab playing Bass Mekanik's Tranzmekanika with the engine off running and feeding from only two optima yellow tops. LOL On the other end of the scale it's still loud enough turn a few heads and trigger a car alarm from time to time rocking Kiss's I love it loud. It's even makes ABBA and Richard Cheese slam, but I don't really want to get into that topic. I do agree that tuning too high does sound like ass, as does tuning to low with something like a single 10 and with 150 watts behind it. In article , (Eric Desrochers) wrote: Captain_Howdy wrote: There is very little music out there in the 23hz range. If you want a full range system, you'll want to reproduce it anyway. The lowest tone in non electronic instrument is the A1 note on a Piano 28hz. Yeah, but we are surrounded by electronic music all day long. Please download "I miss you (Photek remix) by Bjork, for thremendous amount of content in the 25-30 Hz range. Also, some big organ have 32 feet pipes, producing a note of 16 Hz. Such music was indeed recorded. That you can hear it is irrelevant, you can feel it. Music has it's heaviest bass content in the 35-65hz range. Most of the time, yes, but exceptions are becoming the norm now. You'll even notice that most speaker manufactures recommend port tuning frequencies of 33-40hz and a subsonic filter setting between 25-30hz. What drivers and what manufacturer. I'll give you a different example. The 12" Dayton Titanic, a popular DIY sub, when ported, needs a 3.71 cubic-feet, a Fb of 19.52 Hz, for an F3 of 18.22 Hz. This is my definition of a full range sub. It give a box kinda big for a car but should do wonder in a home system. Now, I know about cabin gain and why such a deep response is not desirable in a car. I was just arguing about the "absolute silliness of 23 Hz box" in general. Never say never, as they say... What makes you think that a 45hz port tuning will give you a one-note-wonder is beyond me, I'm not saying a 45 Hz tuning is bad. I'm saying that a driver who would need, say 28 Hz, but you decide to tune it to 45 Hz anyway would probably be very loud but will sound like ****. A lot of the boom box on wheels you hear are overbearing at 45 Hz with not much below 35 Hz. That's where the expression come. I'm sure you have heard it before? To each its own I guess... |
#24
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
Some asshole wrote:
I do agree that tuning too high does sound like ass, as does tuning to low with something like a single 10 and with 150 watts behind it. Since I'm pretty sure that last statement was pointed at me, I must point out that besides being a prick and trying to quantify statements that are a matter of opinion to cover your dick-headedness, you're completely wrong. My single 10, tuned to 26 Hz, being pushed by 150 watts rms, sounds ****ing excellent. ~The Lull |
#25
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
In fact that last statement wasn't pointed at you, not knowing much about your
system other then it being JBL, but with all of the info just given I do agree that it must sound like ****ing something. This is where the matter of opinion comes in to play. In article . com, "The Lull" wrote: Some asshole wrote: I do agree that tuning too high does sound like ass, as does tuning to low with something like a single 10 and with 150 watts behind it. Since I'm pretty sure that last statement was pointed at me, I must point out that besides being a prick and trying to quantify statements that are a matter of opinion to cover your dick-headedness, you're completely wrong. My single 10, tuned to 26 Hz, being pushed by 150 watts rms, sounds ****ing excellent. ~The Lull |
#26
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
In article , (Eric Desrochers) wrote:
Captain_Howdy wrote: What part did you not understand? In article , (Eric Desrochers) wrote: Captain_Howdy wrote: Who in there right mind would tune a port down to 23hz and why?? What kind of stupid question is this? Fine formulas were put toghether more than 30 years ago. You take the driver's T/S parameters, put them into said formulas and the ideal box volume and port tuning are calculated for you. If the port turn out to be tuned at 23, 20 or even 14 Hz, so be it. THIS IS THE CORRECT WAY to determine a box tuning, if sound quality is your goal. 45 Hz one-note-wonder are another story. I guess my question would be what do you find to be wrong with a 23 Hz box? The trouble is, there are more than one formula, and box types. The sound the box makes after its made from one of the alignments, can be categorized from the 15 box alignment types. A good program, will ask you what alignment you want, or provide all the various types. It should at the least, describe the box type the computations are derived from. There was some talk in the Speaker Builder magazine, years ago, basically saying you can also go inbetween box alignments and come up with infinate variations. There are at least 15 well-established alignment categories, such as SSB4 ~Super Fourth-Order Boom Box!, SC4 ~Fourth Order Sub-Chebychev!, QB3 ~Quasi Third-Order alignment!, and discrete alignments such as the Fourth-Order Butterworth ~B4!, Fourth-Order Bessel ~BE4!, and Butterworth Inter-Order ~IB4!. greg |
#27
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
GregS wrote:
There are at least 15 well-established alignment categories, such as SSB4 ~Super Fourth-Order Boom Box!, SC4 ~Fourth Order Sub-Chebychev!, QB3 ~Quasi Third-Order alignment!, and discrete alignments such as the Fourth-Order Butterworth ~B4!, Fourth-Order Bessel ~BE4!, and Butterworth Inter-Order ~IB4!. greg That's correct, of course. But still, a box could end up with a very low tuning, be correctly aligned and sound good. This sub-thread started up with an arguments that very low tuning was *always* silly. -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#28
Posted to rec.audio.car
|
|||
|
|||
Sub enclosures questions
|
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
rec.audio.car FREQUENTLY ASKED QUESTIONS (caution, this is HUGE) | Car Audio | |||
I have some questions about carillons | Vacuum Tubes | |||
I have some questions about carillons | Vacuum Tubes | |||
Questions, questions, questions | Audio Opinions | |||
Seven Questions + | Audio Opinions |