A few questions about subs.

[Dan208 23]

I've been looking around at some different subs, trying to decide what I want to do for a summer project. I want to do my own work, i.e., build my own box, replace door speakers, etc.

I've been looking at subs on Parts Express, like Dayton and Tang Band. I've been all over their websites, but can't find any recommendations for box sizes or types (ported, sealed, etc).

So, my two questions are:

1) How do you calculate box size requirements using the specs that are provided?

2) How can you tell what type of enclosure a sub will work best in?

I'm specifically interested in very small applications, as I'd like to try and run multiple subs (three or more) and try to retain some cargo space. Might also try and squeeze them into the spare tire well.

[altoncustomtech 773]

I'll have to find the information again but the answer to Question #2 is the EBP, Efficiency Bandwidth Product. It's a figure using a few of the theile/small params that can tell you if it's best suited for sealed or ported. On Question #1 there are formula's available to help make those calculations and determine the box size. However, a decent program like WinISD or BassBox Pro can get you 3/4 of the way in the direction you need to go. Another idea is to check to see if the manufacturer has any information available.

There's still no substitute for trial and error either. Just because some program says it's good doesn't mean it will be. You'll have to build it, listen to it and see if it yields the results you're after, and if its not then rebuild. Formulas, websites and software can get you close and sometimes well within the area of respectable results, but a little tweaking and playing can get almost always get it better. It wouldn't hurt get you a copy of Vance Dickason's "Loudspeaker Cook Book" either. It goes through the theories and processes and gives examples and such. Very good source to learn from.

[Dan208 23]

Thanks for the quick reply. I have checked their sites, but haven't tried e-mailing them yet. Might get an answer that way. I've tried WinISD before (quite a while ago), but had no clue what I was doing so it was all Greek to me.

[altoncustomtech 773]

I'm sure you've learned some since then, it may not be so Greek anymore. It's not a bad place to start, you can also try the AJ Design website and a couple others that have calculators on them that can determine enclosure types and sizes. Again, they can get you a start in the right direction, it will help you A LOT to learn the theories and purpose behind enclosure design as well. That can help you figure out where something is going wrong in a design, what to change to get it right, and eventually be able to design without much help after enough time and experience.

[Impious 1,476]

EBP = Fs/Qes

EBP less than or equal to 50 means the driver is best suited for sealed enclosures

EBP between 50 and 90 means the driver can be used in either ported or sealed, but the closer to the extremes you are the better the driver will likely perform in that given enclosure type (i.e. EBP of 60, the driver is a little more suited to sealed but could possibly be used ported)

EBP equal to or greater than 90 means the driver is best suited to ported enclosures

Enclosure size requirements is hard to pin-point without knowing what enclosure type you are looking for. Are you looking for sealed or ported? Also, there isn't a single "requirement" or suggestion. There's an almost infinite number of alignments, some have special names others do not. You can use T/S parameters to predict performance in a given enclosure, the enclosure size necessary to achieve a certain alignment, etc. But you can't look at them and say "This sub needs 1cuft", as that 1cuft enclosure will simply result in one specific alignment out of many possible options. Going larger or smaller may be beneficial depending on the needs and goals.

I was working on a write up of T/S parameters and how to use them. I've been slacking and only have about 5% of it done......I guess maybe I should get back to working on that.....

[edouble101 314]

EBP = Fs/Qes

EBP less than or equal to 50 means the driver is best suited for sealed enclosures

EBP between 50 and 90 means the driver can be used in either ported or sealed, but the closer to the extremes you are the better the driver will likely perform in that given enclosure type (i.e. EBP of 60, the driver is a little more suited to sealed but could possibly be used ported)

EBP equal to or greater than 90 means the driver is best suited to ported enclosures

Enclosure size requirements is hard to pin-point without knowing what enclosure type you are looking for. Are you looking for sealed or ported? Also, there isn't a single "requirement" or suggestion. There's an almost infinite number of alignments, some have special names others do not. You can use T/S parameters to predict performance in a given enclosure, the enclosure size necessary to achieve a certain alignment, etc. But you can't look at them and say "This sub needs 1cuft", as that 1cuft enclosure will simply result in one specific alignment out of many possible options. Going larger or smaller may be beneficial depending on the needs and goals.

I was working on a write up of T/S parameters and how to use them. I've been slacking and only have about 5% of it done......I guess maybe I should get back to working on that.....

Get that write up done man!

[Dan208 23]

EBP = Fs/Qes

EBP less than or equal to 50 means the driver is best suited for sealed enclosures

EBP between 50 and 90 means the driver can be used in either ported or sealed, but the closer to the extremes you are the better the driver will likely perform in that given enclosure type (i.e. EBP of 60, the driver is a little more suited to sealed but could possibly be used ported)

EBP equal to or greater than 90 means the driver is best suited to ported enclosures

Enclosure size requirements is hard to pin-point without knowing what enclosure type you are looking for. Are you looking for sealed or ported? Also, there isn't a single "requirement" or suggestion. There's an almost infinite number of alignments, some have special names others do not. You can use T/S parameters to predict performance in a given enclosure, the enclosure size necessary to achieve a certain alignment, etc. But you can't look at them and say "This sub needs 1cuft", as that 1cuft enclosure will simply result in one specific alignment out of many possible options. Going larger or smaller may be beneficial depending on the needs and goals.

I was working on a write up of T/S parameters and how to use them. I've been slacking and only have about 5% of it done......I guess maybe I should get back to working on that.....

Thanks for the info. It'll help a lot.

I'm not quite sure if I want to go ported or sealed yet. I was leaning towards sealed, since I want to keep the enclosure very small, but I've been reading about a lot of people running some of the subs I've been looking at in really small ported enclosures.

[Dan208 23]

Get that write up done man!

And this.^^^

I did some measuring for an idea I've had for a while; putting a box over each wheel well hump. I had hoped to put two 8's in each one, but after measuring I came up with max dimensions of 10" H x 18" W x 6" D. If I figured correctly, that gives me .44 cubic feet with 1/2" MDF and .37 cubic feet with 3/4" MDF. Not sure if I could find a pair of 8's that would work that small (sealed)?

I also had an idea of something similar to this:

Not sure if 6.5's would go low enough for me. Could be something to try though.

[Impious 1,476]

What are your goals for the system? That has a lot to do with enclosure and sub selection as well.

How much power are you planning on using?

[Dan208 23]

What are your goals for the system? That has a lot to do with enclosure and sub selection as well.

How much power are you planning on using?

These are my main goals:

1) Moderately loud bass

2) Small budget (don't have a set amount just yet)

3) Low power

4) Very small enclosure(s)

I realize that with a system like this I won't be flexing any windshields or winning any competitions (I don't compete anyway), but there's still that part of me that wants people to hear it, see what I have and then start looking around for more subs. I also kind of want to do something a little different than just "a sub in a box in the back of an SUV", and running multiple smaller subs seems like something that might fit that bill.

[Sencheezy 689]

EBP = Fs/Qes

EBP less than or equal to 50 means the driver is best suited for sealed enclosures

EBP between 50 and 90 means the driver can be used in either ported or sealed, but the closer to the extremes you are the better the driver will likely perform in that given enclosure type (i.e. EBP of 60, the driver is a little more suited to sealed but could possibly be used ported)

EBP equal to or greater than 90 means the driver is best suited to ported enclosures

Enclosure size requirements is hard to pin-point without knowing what enclosure type you are looking for. Are you looking for sealed or ported? Also, there isn't a single "requirement" or suggestion. There's an almost infinite number of alignments, some have special names others do not. You can use T/S parameters to predict performance in a given enclosure, the enclosure size necessary to achieve a certain alignment, etc. But you can't look at them and say "This sub needs 1cuft", as that 1cuft enclosure will simply result in one specific alignment out of many possible options. Going larger or smaller may be beneficial depending on the needs and goals.

I was working on a write up of T/S parameters and how to use them. I've been slacking and only have about 5% of it done......I guess maybe I should get back to working on that.....

Yes you should Impious

[Luke.H 33]

Theres this thread on here......T/S Parameters explained but it doesnt really explain how to use them. Impious always does a really good job of explaining that sort of thing if you ask me so his write up would be excellent. Either way that thread was pretty informative

[Impious 1,476]

What are your goals for the system? That has a lot to do with enclosure and sub selection as well.

How much power are you planning on using?

These are my main goals:

1) Moderately loud bass

2) Small budget (don't have a set amount just yet)

3) Low power

4) Very small enclosure(s)

I realize that with a system like this I won't be flexing any windshields or winning any competitions (I don't compete anyway), but there's still that part of me that wants people to hear it, see what I have and then start looking around for more subs. I also kind of want to do something a little different than just "a sub in a box in the back of an SUV", and running multiple smaller subs seems like something that might fit that bill.

IMO your best option then would be to look for something to run ported. It would be a little more difficult to get "significant" output (your "moderately" is probably equivalent to my "really") in the lower frequency region with small subs in a sealed enclosure for various reasons.

Also, there are a few givens in audio. One of them is known as Hoffman's Iron Law. There's a long explanation as to why this is the case, but simply stated you can only achieve two of the following three: 1) Small Enclosure, 2) High Efficiency, 3) Low Frequency Extension. Your list appears to dictate that you are choosing # 1 and # 2, in which case you will necessarily give up # 3. The transfer function of the vehicle will help some in the low frequency extension department....but realistically if you want really low power with moderately high output (i.e. high efficiency) in a small enclosure, you are necessarily going to give up low frequency extension. So you have to ask yourself......moderately loud where in the subbass frequency range? If you want loud from ~50hz and up, for example, your goals should work fine. If you want loud and impressiveness at 30hz, well.....your goals are necessarily going to eliminate that as a possibility. Food for thought.

Do you have a target budget? A target space you would like the enclosure to fit in (dimensions ideally)? A target power level?

[Dan208 23]

Yeah, that's why I'm kind of hesitant to go sealed. I've always run sealed in the past (and had no idea how important the right enclosure was ) and always had what I thought was pretty good output, but I think my Dcon has spoiled me. I love the Dcon, but the box just takes up way too much space. I still might try it sealed but have a feeling I'm going to be disappointed.

My initial budget is $150 for subs, but I may be able to bump it up to around $200. I'm not going to be doing anything until this summer, so I've got a little time to save. Budget for the amp is probably the same ($150-$200).

Space wise I'd like to definitely stay under 1.5 cubes total, but probably more around 1-1.25 total. If I figured correctly, the box for my Dcon is around 1.94 cubes before all displacements.

Not sure about power level yet. I was waiting to decide on what subs to get. Is that the wrong way of going about it?

[Shogen 325]

From what I've read in other threads.. It seems as though the big the sealed enclosure the more low end but less power handling...

What would that mean for say an Xcon... recommended enclosure is 3 cubes and you put it in 4 cubes. The driver can handle 1700 watts. Would that lower it's handling considerably or just a tad? Like 100-200 watts or more like a 500 watt loss... Maybe I've read it wrong or misapplied the information....

[Dan208 23]

From what I've read in other threads.. It seems as though the big the sealed enclosure the more low end but less power handling...

What would that mean for say an Xcon... recommended enclosure is 3 cubes and you put it in 4 cubes. The driver can handle 1700 watts. Would that lower it's handling considerably or just a tad? Like 100-200 watts or more like a 500 watt loss... Maybe I've read it wrong or misapplied the information....

I've wondered this as well.

[Shogen 325]

From what I've read in other threads.. It seems as though the big the sealed enclosure the more low end but less power handling...

What would that mean for say an Xcon... recommended enclosure is 3 cubes and you put it in 4 cubes. The driver can handle 1700 watts. Would that lower it's handling considerably or just a tad? Like 100-200 watts or more like a 500 watt loss... Maybe I've read it wrong or misapplied the information....

anybody??

[Impious 1,476]

From what I've read in other threads.. It seems as though the big the sealed enclosure the more low end but less power handling...

What would that mean for say an Xcon... recommended enclosure is 3 cubes and you put it in 4 cubes. The driver can handle 1700 watts. Would that lower it's handling considerably or just a tad? Like 100-200 watts or more like a 500 watt loss... Maybe I've read it wrong or misapplied the information....

anybody??

Pretty easy to model. Load the driver into an accurate modeling program that graphs cone excursion. Input the two enclosures your comparing as well as the power levels and see how and where the excursion is different in the two enclosures. Ideally you would want to keep the excursion for the driver under Xmax. But the relative differences in excursion will give you an idea of the relative mechanical power handling limits of the enclosure. Obviously if you don't hit Xmax until 10hz then it's not likely going to cause a problem. If you reach Xmax at 30hz, well then you are probably using too much power. Definitely not a perfect model as it doesn't take into account things like power compression..........so even if the graph shows you'll reach Xmax at 30hz with 1kw you may in fact not because of power compression, but it will give you a general idea of the relative differences between enclosures.

[Impious 1,476]

Yeah, that's why I'm kind of hesitant to go sealed. I've always run sealed in the past (and had no idea how important the right enclosure was ) and always had what I thought was pretty good output, but I think my Dcon has spoiled me. I love the Dcon, but the box just takes up way too much space. I still might try it sealed but have a feeling I'm going to be disappointed.

My initial budget is $150 for subs, but I may be able to bump it up to around $200. I'm not going to be doing anything until this summer, so I've got a little time to save. Budget for the amp is probably the same ($150-$200).

Space wise I'd like to definitely stay under 1.5 cubes total, but probably more around 1-1.25 total. If I figured correctly, the box for my Dcon is around 1.94 cubes before all displacements.

Not sure about power level yet. I was waiting to decide on what subs to get. Is that the wrong way of going about it?

Going to be really tough to fit even a single 8" ported in an enclosure with a gross volume of 1-1.25cuft. The problem with small lower tuned enclosures is that the port length ends up being really long. It wouldn't be unusual for the port to actually take up as much or more gross volume than the actual enclosure airspace for the driver.

Honestly for your goals, I think finding a good 10" or 12" driver to run sealed is probably the best option. I know you think it'd be fun to do something with small drivers, but I think it would be fairly difficult to achieve all of your goals with that type of setup. You can run the small drivers sealed and give up some output. You can run small drivers ported and give up some space. Or you can go with a more conventional single larger diameter driver sealed and achieve your space and probably output goals while maybe running a little more power than you originally wanted. And with as cheap as power is these days, if I were going to give up on one of my criteria it would be the power.

[Dan208 23]

Honestly for your goals, I think finding a good 10" or 12" driver to run sealed is probably the best option. I know you think it'd be fun to do something with small drivers, but I think it would be fairly difficult to achieve all of your goals with that type of setup. You can run the small drivers sealed and give up some output. You can run small drivers ported and give up some space. Or you can go with a more conventional single larger diameter driver sealed and achieve your space and probably output goals while maybe running a little more power than you originally wanted. And with as cheap as power is these days, if I were going to give up on one of my criteria it would be the power.

This is what I'm thinking. It seems like the most logical way to go right now. Thanks for all your help.