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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 384 Registered: Dec-08 | Okay so i have been pondering/researching the thought of a 6th order blow through box (as the title suggests). Vehicle: 92' Sonoma standard cab long box Sub: RD Alpha 12v3 dual2 Amp: RD1000.1 Goal: Loud and musical Daily box (SQL) I don't expect this to be show quality, but i do want it to look decent and be weatherproof. Alright my theory is that i want the box to be in the bed of the truck so i only have to cut a fairly small hole just for the ports (not cutting the entire back of the cab out). I have bucket seats in the cab which gives me ~8-10" for port width and ~14" of height. I was thinking something like 2.5 @ 33hz and 1.5 @ 45Hz for the chambers. I was hoping to get some input from those of you who are experienced in this and could help me to avoid problem areas etc. For example: Does anyone know what frequency my vehicle peaks at? Anyone currently using Alpha v3s? Would it at all be beneficial to use aero ports? Any other input would be greatly appreciated Thanks in advance |
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Platinum Member Username: GlasswolfColumbia, SC USA Post Number: 13013 Registered: Dec-03 | "Goal: Loud and musical Daily box (SQL)" Let me stop you right there. 6th order boxes are typically tuned to about 55-65Hz (transfer function range) and are NOT a SQ box in any regard. They are "one note wonder" boxes taht massively increase efficiency so you can blow the doors out of a car for SPL. They sound like total crap for music. I'd go straight ported for a blow through box. |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 385 Registered: Dec-08 | alright, you are definitely the expert, but i have heard of people using 6th order boxes for music. (Canaan and his DD1508). I am not as acute to SQ as you are lol. I just figured i would make the best use of all the space i have, instead of putting a small box in the back, i could double the size and have a second frequency to tune to. Could you predict what it would sound like with it tuned at 33 and 45? I know I don't have an SQ woofer, so i am not expecting perfect flat response. I will look for Canaan's build log... and i have heard that single cab trucks peak at a low frequency, so idk how my sub would react if i tune it to ~28 and ~40 there's a lot of info i don't really know on the dynamics of bandpass boxes, vehicle peaks, things of that nature. |
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Platinum Member Username: GlasswolfColumbia, SC USA Post Number: 13015 Registered: Dec-03 | I figured you'd mention tuning it lower and i almost went into that last night, but I was tired. OK, here's the thing with a bandpass box. Typically, the lower you tune the box, the less efficient it becomes. The purpose for using a bandpass box for most people, is to get more volume or more punch out of a sub than you typically get with a straight 2nd order box. To do this, in a 3rd order, it's usually tuned to about 40-45Hz, which is very boomy (to me anyway). With a 6th order, it's all about the efficiency and gain from the box itself. The higher the box is tuned, the more gain it yields. Now when you tune for peak gain, you typically end up around the 45Hz and 65Hz range, which coincides nicely with the transfer function of the car to add cabin gain to the gain from the box itself, which gives you a really high combined gain, and a lot of output per watt applied. If you tune really low on a 6th order box, you lose all that wonderful gain in efficiency, and you basically have a huge box that has about the same output as a simple ported enclosure. Here's teh thing about tuning high though, you know a ported box and a bandpass box (also technically ported) rolls off like a brick below the tuned frequency. Since a sub amp typically uses a LPF set for about 60-80Hz, and an infrasonic filter for porting set to the tuned frequency (say 45Hz in this case) the result is a box that plays about 70-45Hz, and rolls off at about 24dB/octave above and below those frequencies. This equates to a one-note wonder box. in short, by tuning low, you negate the whole purpose of a 6th order box. |
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Bronze Member Username: Sleste8Shelbyville, MI United States Post Number: 98 Registered: Mar-10 | damn wolf, you broke 13000 posts |
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Bronze Member Username: 410inchl7sBROOKLYN , NEW YORK NEW... Post Number: 17 Registered: Apr-10 | imma break 13000 posts today in 1 day lmao |
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Gold Member Username: SouthernrebelMonroe, Louisiana Team Audible... Post Number: 7980 Registered: Mar-04 | I most case, by tuning your front and rear chambers that close you will get crazy response out of the subs. Usually you end up w/ a very inefficient box. If you can get me a full and accurate list of T/S parameters, I'll see if I can come up w/ something for you. You can get pretty flat response and have good efficiency, but I need those specs. |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 386 Registered: Dec-08 | GlassWolf- Thanks a lot for all your input. your last post helped me understand the principals a lot better. Canaan- I would love to get you a list of T/S parameters, but as it is an Alpha v3, i don't know how long it would take to get an e-mail back from RD, but i'll try. What other kind of box (if any) would you suggest other than a regular ported? |
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Platinum Member Username: GlasswolfColumbia, SC USA Post Number: 13020 Registered: Dec-03 | http://www.rdaudio.net/alpha/alpha.htm v2 full specs 7000 more posts to go. lol |
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Gold Member Username: Kyle_lowePost Number: 1031 Registered: Apr-06 | just call them, they will answer 479-494-3099 i just tested it out and said i had the wrong number |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 387 Registered: Dec-08 | Okay i will try to call them tomorrow and get a full list typed up or saved on WinISD Alpha. And to counteract the potential efficiency loss (and since i am currently under powering it), i will eventually be stepping up to an RD1750, Big 3, and 1/0ga. as soon as my budget allows |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 390 Registered: Dec-08 | And by tomorrow i mean later today., cuz i know no one got anything done on 4/20 haha |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 391 Registered: Dec-08 | Okay, here's what i got from RD: Fs: 31.9 Re: 3.6 Qms: 4.45 Qes: .37 Qts: .325 Rms: 9.245 Cms: .121mm/n Mms: 205.41g BL: 20.56 SPL: 89.89 Vas: 52.35L Xmax: 15mm Xcoil: 53mm Cutout: 276mm Mounting depth: 198mm |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 398 Registered: Dec-08 | Pretty much exactly the same as the v2 specs, but the v3 is made with the HW softparts. I thought it would differ in specs a bit, but i guess not. So any thoughts on a box design? |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 400 Registered: Dec-08 | Anybody? |
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Platinum Member Username: GlasswolfColumbia, SC USA Post Number: 13121 Registered: Dec-03 | what do you want out of this again? SQ? SPL? |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 401 Registered: Dec-08 | I would like to get a nice mix of both, but i'm leaning more towards the SPL side of things. I like the low notes and i have a lot of room to work with. Basically, i want it to be loud, while still retaining some SQ |
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Gold Member Username: SouthernrebelMonroe, Louisiana Team Audible... Post Number: 7995 Registered: Mar-04 | I would throw up a design, but after seeing those specs, I don't know. Being so close to the V2 specs w/ totally different soft parts, it almost makes me think they are BS-specs. That or RD ran out of Alpha recones and threw the HW cones in there they had lying around, lol (which I wouldn't doubt given all the other crap steve pulled) They will work in a 6th order, but I need some dimension on the bed of the truck. I'll punch something together for ya. I would really like to see a broken-in T/S spec list. I'll punch something together for ya. |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 402 Registered: Dec-08 | yeah i don't doubt your theory about the v3 being an Alpha with a HW recone. A shady move for a shady guy lol. Bed Specs: 55.5" wide 14" of useable height right at the front of the bed and 16" from the bottom of the bed to the top edge. on the passenger side, there is 30.5" from the front of the bed to the start of the wheel well on the driver's side, from the front of the bed to the gas tank filler neck is 15" that juts out 2.5" for 8" it pretty much looks like this _____ l..... l )..... l L.. _l ^ I know that was an EXTREMELY crude depiction of a truck bed, but hopefully it makes sense haha |
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Platinum Member Username: GlasswolfColumbia, SC USA Post Number: 13146 Registered: Dec-03 | for what you want, you're really just best off using a large slot vented enclosure @ 28Hz |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 403 Registered: Dec-08 | If i do a 2.5 cu.ft. box @ 28Hz with 38.5sq.in. of port area, that gives me 46.5" of port length. Does that sound correct? |
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Platinum Member Username: GlasswolfColumbia, SC USA Post Number: 13147 Registered: Dec-03 | there are calculators all over the net for that. www.bcae1.com has several |
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Silver Member Username: Simple_smithLapeer, Michigan United States Post Number: 404 Registered: Dec-08 | yeah i just used http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CAL%20Port%20lenth%201.ht m |