how to determine best box size?

[cunokyle 10+ year member]

WinISD is a great program...however, it doesn't really give you the best box size...you have to mess around with it and figure it out yourself by looking at the graphs

 

[PowerNaudio 10+ year member]

actually once you select a sub, and tell it what type of enclosure you're looking to build the first enclosure that it shows you is the best frequency response for that sub, then you tune it to your need.

 

[SSS 18734 5,000+ posts]

thanks for the link, im using the program right now and its so much easier than BB6. I've drawn up two graphs, one of my current setup and one of the one I propose to do. Not really happy with either of them. Is there any way to get a pic of those in my thread so I can discuss it with you guys?

 

[DBfan187 5,000+ posts]

Jmac is much better than any program ...

fixed.//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[PowerNaudio 10+ year member]

Is there any way to get a pic of those in my thread so I can discuss it with you guys?

print Scrn button on the keyboard and open your favorite graphics software control V in to a new image, resize then save as .jpeg, and post.

 

[SSS 18734 5,000+ posts]

This response curve is from 10 - 100hz.

The one that peaks at around 50hz is my current box. Its fine up until then, but bass below about 40hz isn't nearly loud enough.

The other one is a box that is 2 cu.ft. tuned to 35hz. It's alright, but it doesnt peak as high as I would like it to. That part is ok, but what I am concerned about is the 40hz - 80hz response, its at an average of -4db.

I've tried playing with the program by increasing box size and playing with the tuning , but it seems the only way to flatten out the 40-80hz response is to tune relatively high and lose most of my lower spectrum of bass. //content.invisioncic.com/y282845/emoticons/crying.gif.ec0ebefe590df0251476573bc49e46d8.gif

Is there any way to flatten out the response curve? or am I stuck with what i've already seen?

 

[PowerNaudio 10+ year member]

Is there any way to flatten out the response curve? or am I stuck with what i've already seen?

you're pretty much stuck, unless you get a different sub.

although that curve is not as bad as it looks i would go with the lowest frequency response.

 

[DBfan187 5,000+ posts]

make the box bigger, thus resulting in power loss though.

 

[SSS 18734 5,000+ posts]

heres two more I came up with.

2.5 cu.ft. tuned to 32hz

2.0 cu.ft. tuned to 38hz.

the first one has an average of 1-2 db less output throughout the 45hz - 70hz range, but doesnt really cut out until the mid 20's.

On the other hand, the one tuned to 38hz produces more output through most of the frequency range, but quickly cuts out at around 35hz, where there are still usable frequencies.

Which one would be better in your opinions? Or would something in between, tuned to 35hz be a better choice, such as the one in the graph I posted before this.

Sorry for all the questions, im 100% new to all this stuff. Thanks for bearing with me:veryhapp:

 

[SSS 18734 5,000+ posts]

also, another question. Say I want to have a single 3.5" port, to achieve a tuning of 35hz I need it to be 10" long.

If I enter that I want two ports, the length goes up to about 22." Does that mean that EACH port needs to be 22" long, or is the the combined length of the two ports, so 11" per port?

 

[kuijo 10+ year member]

the more ports you have the smaller or longer they have to be. Its been brought up they also offer less port area.

 

[SSS 18734 5,000+ posts]

Well I'm still playin around with designs with little luck, and I thought I'd put all my designs on one graph to make it easier to see the differences between them.

Red = current box 1.5 cu.ft. @48hz

Yellow = 2.5cu.ft. @ 32hz

Blue = 2.2cu.ft. @35hz

Green = 2cu.ft. @40hz

Im leaning toward the yellow one, it seems to be the most linear and have decent response all the way down to about 25hz, but it in theory will produce substantially less output than any of the others, especially my current one (but low end there cuts off at like 40hz:uhoh: ). And there seems to be no hope in flattening out the mid-bass response besides a very high tuning which I want to avoid.

Will I really notice the decreased output, and will it be a good trade-off to be able to get the sub to play notes down to about 25hz? Will other factors, such as the power im sending to them (1200 watts), and cabin gain naturally smooth out the frequency response? This box design is complicated stuff.

 

[SSS 18734 5,000+ posts]

If you have BB6P, you should be using that ... It can estimate cabin gain, it takes into account the effects of port area, and uses more complex and accurate formulae ...

I've tried it and have succeeded in making a rough graph, but I'm having a lot of trouble fine-tuning and entering the more advanced parameters. The help menu isn't of too much help either.

Are there any tutorials/walkthroughs for BBP6? cuz that would be sweet //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[GTonDubs 10+ year member]

Beat_Dominator - well its a little more complicated than that. If I have say, a 1 cu.ft. box tuned to 35hz, it will perform quite differently from a box 5 cu.ft. in size, right? Of course it will. So basically, since I dont have a lot of space restrictions, I want to figure out the best volume/tuning combination for my particular sub, and be able to get these subs to play nice and low while still maintaining a lot of SPL. a flat response curve is not a concern at all, a large peak is fine with me.
DBfan - how did you get that, if you mind me asking?

a 1 cubic foot tuned to 35 hz will not like realy low notes to well