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Advantages of a bandpass box

 

Silver Member
Username: Cwruck

Post Number: 154
Registered: Feb-10
hi guys i just have a quick question, i was wondering what are the advantages of using a bandpass box? I know many people dont like them but how come? Is it because you dont really get a flat response out of them? i know they have huge peaks that would work for hip hop type of music which is all i really listen to in my car, i get into the classic rock and rock in my house so i see that as an advantage to me if i just want to be loud.
do they bottom out? I would think they wouldnt but im not quite sure, i would have subs that can easily drop down to 20 hz or so, but of course regular non slowed down music never really gets that low, but what about around 25-27 hz? would a bandpass bottom out the subs in those frequencies?
just want to try something new and i want a loud system, i can do all my critical listening at home, but its fun to kind of compete with my friends systems you know? except it will be hard considering one of them has a dc lv 5 18" haha
 

Platinum Member
Username: Glasswolf

Post Number: 13623
Registered: Dec-03
bandpass are OK, but they are large boxes, and to get a flat response, you lose all the added gain. If you tune the box for peak gain, then the box becomes very peaky. It's a trade-off.

http://www.diysubwoofers.org/

http://www.glasswolf.net/papers/boxtypes.html
 

Silver Member
Username: Cwruck

Post Number: 159
Registered: Feb-10
ya im not looking for a flat response, i have all that in my home stereo, im looking at just getting as loud as i can with 2 12s, they will more than likely be dc audio lv 3s. just want to be loud from 30-50 hz and sound decent from 25 to 30 and 50 to 60. mostly like i said 30-50 as thats where the majority of the frequencies are in the music i play.
Will a bandpass do this? also will it bottom out the speakers?
 

Platinum Member
Username: Glasswolf

Post Number: 13626
Registered: Dec-03
"sound decent from 25 to 30 and 50 to 60."

try 6th order band-pass.

tune to both of those frequencies.

you will need a subsonic filter below the lower tuned frequency however, and possibly a notch filter to tame the box a bit.

see the DIY woofers page, the 6th order link on the left.
 

Gold Member
Username: Jakeyplaysbass

St. Louis, MO / ASU

Post Number: 3795
Registered: Jul-05
In my opinion the only reason you shouldn't want a relatively flat curve is if your competing in dB competitions. Unless you are listening to 30-50hz sweeps all day long (highly doubt it), you will play more than just those frequencies. You will be disappointed in the system and with the right box could get just as loud (or damn close to it) with a flat response.

The easiest ways to get louder is by doubling the power, adding more woofers, or increasing port size/design. Designing a box to be loud on just a few notes probably isn't your best option.

On a side note, if you give me a budget and space limitations I will give you a couple system ideas. I'm not the biggest SPL guy... but i've dabbled in loud systems before.
 

Platinum Member
Username: Glasswolf

Post Number: 13639
Registered: Dec-03
If he wants loud at the expense of musicality then that's his call.

power is the least efficient means of increasing volume there is. Double the power is only a =3dB gain in output, which you could achieve with the same power by just adding a second sub. Finding a driver with better sensitivity is a much more efficient way to increase output. The increase in poer will almost always require an upgrade to teh electrical system as well.
 

Silver Member
Username: Cwruck

Post Number: 160
Registered: Feb-10
6th order seems like its too easy to mess up, im not really the best box builder and i dont have much free time to do it.
for subs im looking at getting 2 dc lv 3 12's dvc 4 ohm and ran at 1 ohm on a sundown sae-1200d, right now i have an re sx on the sundown at 1 ohm and it is loud but i know i can do louder.
it seems no one has anything positive to say about bandpass boxes.. what other frequencies are going to be played in bass? when do you hear below 25 hz in hip hop or r&b songs? I dont listen to the music slowed down. It normally stays around 30-40 and sometimes in the 50s and 60s but the majority of 30-40 hence the reason sub manufactorers recommend a tuning of 32-35 hz generally if the sub is in a ported enclosure.
you can only make a box so big, im only running 12s in a small bmw 325i trunk. i cant do 15s or 18s. 4.0 cu ft is hard to fit in my trunk, ive done it before
im not looking for a perfect flat response, thats rather extremely hard to do anyways without rediculous amounts of tuning, and still different songs will throw it off.
like i said i have a very musical home audio system. in my car its about being loud but still sounding good. i do run dls comps...
i know people may not completely agree with what i want to do, but its my money you know?
Even though it sounds like bandpasses are horrible i will still probably try one anyways just to see what i think about it.
 

Platinum Member
Username: Rovin

1 15 = 152.5 DBs ...Trinidad & T...

Post Number: 16316
Registered: Jul-05
i have worked with 2 12s those DC L3 b4 a while ago - good subs but not as low\smooth as say RE SE

iirc : use about 2cuft each with 12sq" of port \cuft tuned about 35hz

if space is an issue buy 2 4" aeroports from parts express & u will get good output & sound ...


http://www.parts-express.com/pe/showdetl.cfm?Partnumber=268-352
 

Platinum Member
Username: Glasswolf

Post Number: 13653
Registered: Dec-03
6th order is tricky. you have to be accurate in both the math and the cuts. the result for failure is a blown sub.

Deep bass, even in rap, rock, and R&B is in the 30Hz range, yes. The reason people tune to 28-32Hz is because a ported box tends to peak in output just above the tuned frequency, which is golden for that deep bass that you feel as opposed to that boomy sort of bass you find on old 2live crew CDs.

Personally I like the deep, tight bass I get from sealed enclosures and low-tuned ported boxes, but some people like that warm, boomy bass which is more akin to what you'd hear from prefabbed, pre-tuned enclosures from BB, or from bass tubes and the like which are tuned more in the 40-45Hz range.

It's personal taste as always. I prefer the sound of an 808 or a timpani drum to synthesizers.
 

Silver Member
Username: Cwruck

Post Number: 161
Registered: Feb-10
ya not trying to blow any subs.
exactly how can someone say the frequencies i suggested wont cover what i listen to? like i said i know exactly what i want and i feel a bandpass can do that
i just want to learn a little more about them and the advantages of them, i am well aware they do not have a flat response, i said it myself
i am well aware of the fact they wont have the best "sq" because of the fact they dont have a flat response, but honestly someone please show me a frequency sweep in their car that has a perfect flat response.
i want huge peaks from 30-50 hz as i have stated many times, thats the whole idea of me being interesred in them.
just wanted some info and wondering for the situation i am in and want to do is a bandpass going to work?
still not sure if they distort below tuning frequency like a ported box..
could you help me out a little glasswolf?
i understand bandpass boxes are going to have negatives when using them, but what type of box doesnt have any negatives? I'm looking for the advantages but all im hearing is the negatives that i have already stated they will have
 

Platinum Member
Username: Glasswolf

Post Number: 13658
Registered: Dec-03
actually bandpass do sound really good, within their bandpass range. The reason for this is that a bandpass box masks coloration from harmonics better than a normal ported box can.

In regards to the tuned frequencies, you'll need a 12dB or steeper cut-off with the subsonic filter below the tuned frequency of your bandpass box. Like with a ported box (third order) the reason for the subsonic filter isn't distortion. The reason you need to cut off anything below the tuned frequency is because the driver becomes very hard to control below that point, and with the power levels applied to these speakers, the result would be like having the sub without any box or suspension. The driver can unload, and over-excurt. When this happens with a bandpass box, you'll be picking pieces of your driver up from the chamber of the enclosure.

It's not really about distortion, it's about acoustic suspension.
 

Platinum Member
Username: Glasswolf

Post Number: 13659
Registered: Dec-03
Oh, and a 4th order and even a 6th order enclosure can have a flat response, with the decreased harmonics. The trade-off for this however is enclosure size (versus sealed) and decreased gain from the enclosure. (no increase in output)
 

Silver Member
Username: Cwruck

Post Number: 162
Registered: Feb-10
thanks glasswolf i appreciate that. i was thinking the same thing that you said with the subsonic, like right now i have my subsonic turned at 32-34 hz or so because my box is tuned to 38 hz, i probably should have it higher but i stay away from lower bass songs or i dont turn it up as loud.
is there anywhere good to buy them? i just dont have the time to build one myself. i see some on ebay made of 3/4 mdf and they say i can drop down to 25-30 hz which is what i want, i just dont know if its a good box or not..
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