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View Full Version : How accurate are manufacture suggestions for enclosure design??



VWBobby
11-08-2013, 08:01 PM
I have been plugging a lot of numbers into WinISD, the RE L-Port box calc and a few other free box programs.
I keep getting sizes that are a little larger than the manufacture recommended "optimum" enclosures... Both ported and sealed.

I have ran into this problem with 3 - 5 different models and types of subs. Dayton, Phoenix Gold, Massive, etc.

Specifically, I am trying to design a box for my new Massive Audio Hippo 122. I was thinking a 29 - 32hz tune would be good for a '65 VW Bus.

It calls for 2.59 CF ported @ 36hz. That seems like a pretty high tune...?? I would like it closer to 31 or 32hz, no?
Sealed is 1.58 @ F3 of 68hz! What gives?

A little help would be much appreciated.

Thank you!
-Bobby

VWBobby
11-09-2013, 03:17 PM
75 views and no response. Nobody likes to help anymore?

vibe
11-09-2013, 03:21 PM
wish i could help you man i dont know much about this. im going through box issues myself. maybe since there will be 2 replys tho the people that do konw will have that brought to there attention and u can get the imput u need. sorry mate

garychoffmann
11-09-2013, 03:23 PM
Really depends on the manufacturer. Most rec'd boxes are more for a generic listening audience. The boxes are a trade off between size/all listening styles/broad frequency response. Not necessarily a flat response. Manufacturers do spend some time modeling the subs and give you a box that plays good enough in generic listening conditions.

VWBobby
11-09-2013, 03:26 PM
It's ok. I appreciate your reply and honesty!

Maybe this will help?

Vehicle : 1965 VW Bus (van)
Location in the vehicle: Rear seat base
Space available (Length x Width x Height): 28 x 18 x 18 inches
Subwoofer make and model: Massive Audio Hippo 122
Subwoofer Size: 12
Number of Subwoofers: 1
Type of Port (Kerfed, Slot, Aero, etc.): Prefer slot or aero port.
What type of music do you like?: Metal, Dubstep, Rap, Bass
Is your goal SPL or Everyday Music?: Everyday with ability to comp....
Tuning Freq (Hz): prefer 28 - 32hz, but manufacture suggests 36hz?
Volume : Around 2 - 3CF net
Questions: Suggested tuning, suggested box design (sealed, ported, or 4th order)?

Powering it with 1500 WRMS...

Thanks again :)

audio_phill
11-09-2013, 03:28 PM
plug their tsp's into WinIsd. Most companies today give boxes that would be loud and minimal bandwidth vs clear and wide bandwidth, but given the current craze is spl that fits the demographic fine.

WinISD (though not capable of plotting le effects on the curve unless you use Pro Alpha version, is only to be used as a quick reference) is a useful tool in spotting less than ideal recommendations in box volumes.

Pretty simple program to use, and its free to download or is available on their site to use without downloading. Use it enough and play around with the parameters and its easy to figure out the affects of the box with changes in Qts.

garychoffmann
11-09-2013, 03:35 PM
Personally, as I do with almost every set up I build, start with largest aesthetically pleasing box. Add an adjustable aero port and start playing with it till it suits your needs and vehicle acoustics. I would start with 3 cubic feet and a 4 inch pvc pipe. Start your tuning around 28hz and see how you like it. If its muddy and uncontrolled add mass to the box (blocks of wood pr Styrofoam blocks. Cut pipe till you get the response your looking for. If you had to add mass cut braces to take up that much space. Swap out the pvc for your aero and you have a box built and tuned in your car. Can't get a lot better than that. Lots of extra work but worth the extra few hours of effort

winkychevelle
11-09-2013, 03:37 PM
One thing those programs cant calculate is cabin gain. Which the sealed box says 63hz but in the car it may very well be able to drop down to 30hz after cabin gain

VWBobby
11-09-2013, 04:10 PM
The manufacture must be factoring in the cabin gain, I'm guessing.... I am using WinISD and other programs.
As I was saying before, every sub I've modeled graphs better with a little larger box and little lower tune. A lot of the recommend enclosures have a spike around 32- 38hz or so when graphed on the SPL in WinISD. If I design a box, I can smooth that out quite a bit or move the spike a little lower to give a slight boost around 30hz (1 - 3db).
It's pretty easy to tune for a flat response, but I'm not sure what that would sound like in-car? I figure having a fast rising curve on paper, or a slight bump around 30hz would help with the low 25 - 38hz notes in rap and other electronic music... Any thoughts on this? Tuning around 36hz would have more "boom" right? I don't want as much boom as having a smooth fat bandwidth from ~25hz - 60hz if possible.... I'm know I'm asking for a lot, right? :)

audio_phill
11-09-2013, 04:14 PM
Personally, as I do with almost every set up I build, start with largest aesthetically pleasing box. Add an adjustable aero port and start playing with it till it suits your needs and vehicle acoustics. I would start with 3 cubic feet and a 4 inch pvc pipe. Start your tuning around 28hz and see how you like it. If its muddy and uncontrolled add mass to the box (blocks of wood pr Styrofoam blocks. Cut pipe till you get the response your looking for. If you had to add mass cut braces to take up that much space. Swap out the pvc for your aero and you have a box built and tuned in your car. Can't get a lot better than that. Lots of extra work but worth the extra few hours of effort

or, you could use a spat of technology and save yourself lots of trouble.


One thing those programs cant calculate is cabin gain. Which the sealed box says 63hz but in the car it may very well be able to drop down to 30hz after cabin gain

f3 will be lower thanks to gain, but vehichles have similar sound profiles by cabin type, AE has posted several rta's that show great examples of vehicle acoustics.

But a person should never rely on cabin gain as a way to achieve extension to a desired frequency,

audio_phill
11-09-2013, 04:30 PM
The manufacture must be factoring in the cabin gain, I'm guessing.... I am using WinISD and other programs.
As I was saying before, every sub I've modeled graphs better with a little larger box and little lower tune. A lot of the recommend enclosures have a spike around 32- 38hz or so when graphed on the SPL in WinISD. If I design a box, I can smooth that out quite a bit or move the spike a little lower to give a slight boost around 30hz (1 - 3db).
It's pretty easy to tune for a flat response, but I'm not sure what that would sound like in-car? I figure having a fast rising curve on paper, or a slight bump around 30hz would help with the low 25 - 38hz notes in rap and other electronic music... Any thoughts on this? Tuning around 36hz would have more "boom" right? I don't want as much boom as having a smooth fat bandwidth from ~25hz - 60hz if possible.... I'm know I'm asking for a lot, right? :)

Nope, thats all i ask for from a system with your goals lol.

tuning lower with enough volume is seldom a bad thing and will definitely help in the range youre after

hispls
11-09-2013, 04:42 PM
The reason manufacturers lie about "optimum" box size is that the consumers are stupid and for the most part like bragging about how big their woofers are. Similar reason why manufacturers opt for less efficient designs just for the sake of throwing more power into a woofer. Your average consumer would be happier with the exact same SPL if they could tell their buddies they were running 5KW and 18's than having to only use 2500W and 3 12'sa to get the same results.

Companies realize that whoever promises the most power handling and the smallest box size for any given size woofer will get the money of the uninformed. There are few companies that really recommend optimum volume IMO.

I think if people actually tested less woofer and more box you'd see a lot of people change their tune about how much cone area you can cram into a couple cubic feet. In fact most of my testing I have found that my SPL is more limited by the volume of my box than the cone area I use.

tl:dr Use the modeling software over "recommended" size every time.

VWBobby
11-10-2013, 08:47 AM
That makes a lot of sense about the marketing towards people who are looking for big power handling and small box requirements. It seems that 70% of the forum boners (right now) are huge power subs. The other 30% are the SA series and everything else with a rating of about 600W RMS.

That must be why I remember when 300W subs could get very loud and people didn't need more than 800-1200 watts at most. A lot looser suspension, smaller coils, lighter materials.

Thanks for the tip about the magazine article with the cabin gain graphs of multiple vehicles. I found it interesting that the smaller cars were as close to the huge SUV's in cabin gain response.
http://farm4.static.flickr.com/3194/2516534482_b0d155d5ac_o.jpg

I think I will build a little big and tune a little low as planned. Thanks for the help again guys, just making sure I wasn't making a huge mistake or seeing things that weren't there. ;) Next build will be a lower power handling, multiple woofer build.....just like I used to do in the past. :)

hispls
11-10-2013, 09:58 AM
Next build will be a lower power handling, multiple woofer build.....just like I used to do in the past. :)

Make no mistake, a lot of your bigger/premium woofers are well worth the money and investment in power and sufficient box size IF you need a lot of output.

The real downside is that there are few woofers that are really high quality that are built to withstand less than 600-800W these days since that's not what the market demands and power is so cheap. For example, for all the JL W0 was when it first came out (power handling of about 200w), I wouldn't put 4 of them against a single really high end modern woofer like JBL GTi MKII, LMS 5400, or RE XXX for potential output and SQ. Just understand to whom manufacturers are trying to appeal, and plan around what the maket has to offer.

DonH
11-16-2013, 03:43 PM
Make no mistake, a lot of your bigger/premium woofers are well worth the money and investment in power and sufficient box size IF you need a lot of output.

The real downside is that there are few woofers that are really high quality that are built to withstand less than 600-800W these days since that's not what the market demands and power is so cheap. For example, for all the JL W0 was when it first came out (power handling of about 200w), I wouldn't put 4 of them against a single really high end modern woofer like JBL GTi MKII, LMS 5400, or RE XXX for potential output and SQ. Just understand to whom manufacturers are trying to appeal, and plan around what the maket has to offer.

IDQ's that i build ;)