Is a small ported box possible?? Or is passive radiator the only way to go...
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Bronze Member Username: KujoPost Number: 74 Registered: Jun-05 | Soo I bought one of these beastly little subs, a tcsounds OEM TC10 (http://www.tcsounds.com/forums/index.php?showtopic=1013&st=0). They are recomended for a .3-.6cuft sealed enclosure, or a .6cuft enclosure with a passive radiator. Their passive radiator was designed to match this beefy sub, and runs an extra $125. I'm usualy a ported guy, but because I want to save some space in my trunk, I built a .5cuft sealed sono tube. After I tried it out though, I decided ported is really the only way to go for me. Now my question for you all- Being that I want to try and save space if I can, is it possible to make a smaller ported box either with round ports or slot port, with less than 1cuft airspace that can work for this sub?? If it is possible, can any of you help me with the design of it? If not, then would the PR be worth the investment? Honestly I didnt even know what a passive radiator was untill I came across this sub... so I've been sceptical on whether or not I want to buy one especially with it being almost as much as I paid for the sub itself. However, if it comes down to it being the only way to go, then I could make another sono tube, with sub on one end, and PR on the other end. Any help would be awesome. Thanks to all who can! |
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Gold Member Username: JohnfiacA-ToWn, Kingkong ain... I got Chuck ... Post Number: 2836 Registered: Mar-06 | the PR would give you a small DB increase, its just like having more cone area really, the pressure from the box moves it with the sub |
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Silver Member Username: Jesse59672OK Post Number: 338 Registered: Feb-07 | killa get on aim lol |
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Gold Member Username: Extrmndor3IF U HEAR ME... crazydbs.com Post Number: 4943 Registered: Feb-06 | nope u wrong killa.. the passive radiator acts like port... its manily a port on each passive radiator it will come with weights that u can put on the radiator cone to chage the tuning of the radiator in your case a small ported box will cause lots of turbulence in that small space.... so u will have to go with a passive radiator with a box that small u can put the radiator on the back or the side of the box depending wat car do you have... u could do it in crx box style... with that u will gain the 3 edbs that u will get from the ported box tat its a fact and its proven alraedy ... plus depending on yoru car u will have cabin gain... go with a radiator  |
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Bronze Member Username: KujoPost Number: 75 Registered: Jun-05 | Its going in a WRX. I'm just going to be moving soon to a bigger city, so is why I want to save some trunk space for whatever life throws at me lol. |
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Gold Member Username: Extrmndor3IF U HEAR ME... crazydbs.com Post Number: 4944 Registered: Feb-06 | radiator its the way to go in your case u will mostly gain that 3dbs average that u willg ain of having a nice ported box. |
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Gold Member Username: JohnfiacA-ToWn, Kingkong ain... I got Chuck ... Post Number: 2838 Registered: Mar-06 | it still does what i said to tho... (used a sub kinda like one before) |
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Gold Member Username: InsearchofbassPost Number: 5058 Registered: Jun-04 | I used a blown 12 and cut the magnet out and used it as a passive radiator in my first box with two 10's in it....you could add a weight system to it youself if you want to tune it....the passive radiator I used from the blown 12 worked great and it was free |
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Gold Member Username: InsearchofbassPost Number: 5060 Registered: Jun-04 | http://www.diysubwoofers.org/prd/ The Subwoofer DIY Page Passive Radiator Systems last updated: 24 April 2006 Passive radiator systems are very similar in operation to ported systems. However, instead of a port, the passive radiator system uses a passive radiator (also known as a "drone cone") to extend the system's low frequency response. The response of a passive radiator system is similar to that of a ported system using the same driver. However, the cutoff (-3dB) frequency is slightly higher, and the cutoff slope is deeper, mostly due to the presence of a "notch" in the frequency response corresponding to the passive radiator's resonance frequency. However, this notch is normally located far outside of the passband of the system, and therefore usually of little audible significance. The larger the passive radiator, the lower the passive radiator's resonance frequency (for the same target Fb), and the further the notch is out of the passband. To design a passive radiator alignment, start with a simple ported alignment using that driver that provides the desired box size and frequency response. Then, use the diameter of your chosen passive radiator as the "port diameter", and use this to calculate the required port length. Work out the volume occupied by this port and then use this to calculate the mass of air occupied by this port. The result is the required mass of the passive radiator. If it is too small, use a larger passive radiator and repeat the calculations. Example: Driver: Vas: 2 cu.ft. Qts: 0.30 Fs: 30 Hz Diameter: 8 in. Ported Alignment (QB3): Vb = 0.70 cu.ft. Fb = 39.4 Hz Now, we need to select an appropriately-sized passive radiator. ALWAYS use a passive radiator that is larger in diameter than the active driver, as the displacement of the passive radiator usually has to be 1.5 to 2 times that of the driver. If it's not possible to use one large passive radiator, then you can use two or more smaller ones, and tune them by working out the effective diameter from the combined surface area of the radiators. Note that the effective diameter of the radiator is approximately equivalent to the diameter of the passive radiator's face plus 1/3 of the surround. If unsure, use the quoted Sd for that radiator, then use the following equation to determine the effective radius: R = (Sd/PI)^0.5 In this case, we choose to use a passive radiator that has an effective radius of 5 inches (roughly corresponding to a "12-inch" passive radiator). "Port" Radius = 5 in. Required Port Length = 186.1 in. "Port" Volume = (PI*R^2)*h = (3.14 *5^2)*186.1 = 14609 cu.in. = 8.45 cu.ft. = 0.2393 m^3 Mass = "Port" Volume * Density of Air = 0.2393 * 1.21 = 0.289553 kg = 290 g The passive radiator therefore has to have a weight of 290g. To achieve this, start with a passive radiator with lower mass, then add weight to make up the difference. To measure the resonance frequency of the passive radiator, install it in a free-air baffle (e.g. the box it's going in, without the driver in place), then hold a driver, driven by a sine wave generator, as close as possible to the passive radiator, then vary the frequency. At the passive radiator's resonance frequency, you should see the greatest peak to peak excursion of the passive radiator. Like their ported cousins, passive radiator systems are much more sensitive to misaligned parameters than sealed enclosure systems, which makes their construction more difficult for the beginning DIYer. I advise that you don't attempt to build these systems, unless you're certain that the T/S parameters for the driver that you want to use are correct. Almost any driver can be used in a passive enclosure system, however, only drivers which have a Qts value between 0.2 to 0.5 will generally give satisfactory results. If the driver has a Qts above 0.4, try using it in a sealed enclosure or single reflex bandpass system instead. Passive Radiator System projects on the internet John Janowitz's Thunder 12 Dual PR subwoofer Louis Lung's Shiva/PR subwoofer Adrian Mack's Peerless PR subwoofer Rob Lloyd's Shiva/PR subwoofer Sander Sassen's 10" PR subwoofer My thanks to Tom Danley and Deon Bearden of the DIY Loudspeakers Mailing List for providing these guidelines for designing Passive Radiators systems. |
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Bronze Member Username: KujoPost Number: 76 Registered: Jun-05 | Now I'm definately not any sort of expert, but since I would have to save up for a PR, I came up with a slot port design that I could maybe do in the mean time. Going off of a slot ported calculator from carstereo.com, I came up with this design...  I first started the design with a 12" H x13" W x12" D rectangle (external dimensions give me about .73cuft volume internal). Then, I wrapped a 1.5" slot port all the way around the outside, and partly inside. I used the slot vent calculator from carstereo.com and with a volume of .7cuft, tuned to 32Hz with a slot port of 1.5"W x 10.5"H, it needed to be about 55.19" long. Does this design look like it could work?? |
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Bronze Member Username: KujoPost Number: 77 Registered: Jun-05 | Now I'm definately not any sort of expert, but since I would have to save up for a PR, I came up with a slot port design that I could maybe do in the mean time. Going off of a slot ported calculator from carstereo.com, I came up with this design... I first started the design with a 12" H x13" W x12" D rectangle (external dimensions give me about .73cuft volume internal). Then, I wrapped a 1.5" slot port all the way around the outside, and partly inside. I used the slot vent calculator from carstereo.com and with a volume of .7cuft, tuned to 32Hz with a slot port of 1.5"W x 10.5"H, it needed to be about 55.19" long. Does this design look like it could work?? |
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