just 2 know: If bandpass have narrow freq. response why do manu. curves show wider?

[cad_3326 10+ year member]

So, I'm gonna do sealed anyway cause I'm not in this for spl, but I was reading some box-building threads, and the consistent belief is that a bandpass box narrows the frequency response of the sub... However, if you go to, say, the image dynamics tech pages, and look at the bandpass frequency response graphs, they show up as having a flatter, wider frequency response than the sealed or ported boxes, so why would bandpass boxes be known as one note wonders? of course, when I say flatter, I'm only referring to the 20hz-100hz range or so, but that's really where most of the sub response is expected to lie, anyway. Keep in mind that I don't want one I never even considered it: I want the cleaner thump of sealed, but I just wondered.

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[JimJ 5,000+ posts]

When properly built and used for a driver that it works with, a 4th order bandpass can have a very, very flat frequency response over the bandwidth it's built for. As you go up in orders, bandwidth decreases...

 

[themommyvan 10+ year member]

Bandpasses can be made to have higher peaks at certain freqs. Which is why a lot of

competitors use them.

 

[Immacomputer 10+ year member]

They're commonly known as one note wonders because many pre-fab bandpass enclosures have a very narrow bandwidth and very high efficiency. This makes them boomy and appealing to the masses that like something that's loud and cheap. Custom bandpass enclosure can have any bandwidth you would like from them. However, increasing bandwidth usually means a decrease in efficiency.

 

[cad_3326 10+ year member]

So, I'm still missing where this turns sour... You say you can set up a bandpass box to respond to a specific frequency range of interest, and make it flat, and have pretty good (though decreased if the range is wide) efficiency... I realize that all of that requires the building of a good box, but if the manufacturure has specs for the box, and the expected response, and you build it accurately, then it seems like you'd get what you want... I get that prefab bandpass are a complete joke (duh, the volumes and ports are very specific to the driver) but I'm still not hearing why bandpass boxes are overall bad... Now it makes sense that they wouldn't be good for SQ, maybe not even acceptable, because I would imagine that the box has a lot of resonance that doesn't vanish when the next note is played. But, as for an SPL setup with a fairly flat response curve (which I guess would be about as good a definition of SQL as you can get) it seems like a well made bandpass box might be pretty desireable... so what is the all redeeming failure of the bandpass box?

 

[GemaRastem 10+ year member]

bandpass boxes are usually larger, making them harder to design for the car audio community

 

[Immacomputer 10+ year member]

I wouldn't ever say that bandpass boxes are failures and that anybody who says that really doesn't have a good understanding of them. I would say their biggest drawbacks are size, design, and the difficulty to see the sub struggle mechanically (but the latter is avoidable).

In a pure SQ view, they do have issues with group delay and transient response due to the higher tuning frequencies often found in different bandpass enclosures.

 

[60ndown 10+ year member]

]so what is the all redeeming succsess of the bandpass box?[/b]

http://www.decware.com

the deathbox.

A secret to successful car audio systems is of course your subwoofer, or foundation. Understanding that a car is not a living room, but rather a box is the first step to understanding cabin gain. When you put a box in a car, you are actually putting a box inside a bigger box, thus creating additional orders. Because of this reactive capacitance all around your box, having two 12" woofers openly firing into the car is usually asking for all kinds of performance variables. This is the reason why one enclosure will sound good in one car, and terrible in another.

We have determined that to minimize these loading problems, and to allow an enclosure to breath freely, it must be consistent with a small box to room ratio of less than 15%. It is also desirable to control the air space in front of the woofer by removing the capacitance created by flexing metal in your trunk. This is why we chose a band pass design to begin with.

 

[vehementSPL 10+ year member]

Hmm well it depends on what freq you are looking for CAD. Honestly most sealed boxes and be extremely flat over a few hundred hertz which is totally pointless in my opinion. I have a bandpass that is EXTREMELY loud off 500 watts and it is almost completely flat from 38 hz to 60hz.. rap is LOUD country is LOUD. rock is LOUD. Most people think of roll off and they think a good roll of is playing rock and rap. well you can do that with about 25hz lol. Bandpass typically requires a bit of size. But if you want SQ and insane output bandpass can be your friend. Problem is bandpass is MUCH harder to design than ported and about 1000 times harder than sealed. So unless you are buying prefab or know your stuff very well don't even attempt

 

[cad_3326 10+ year member]

Well, I don't see myself attempting it, but nonetheless, if I wanted to, I don't see how I could go wrong if I directly followed the manufacturer's exact box diagram; I mean really if a manufacturer says, you'll need 2 23"x12" and 2 13" x 15" and 2 12" x 9" etc. 3/4 in mdf and put 'em together like this... I really don't see how well you have to know your stuff to follow those directions (few manufacturers have that but id has one). And I know for sure that 38-60hz response would NOT make me happy AT ALL... C'mon, we're talking about metal here, and yes, I've got midbass speakers (RE XXX) that will hit that 80hz hard (maybe decent at 70), but I've got to have some transtion in the bass beyond 60 (that's a personal preference though and you've got yours too)... And suggesting buying a prefab bandpass box is CRAZY! I may not know much, but even without anyone telling me, I knew that a prefab bandpass is about the most retarded idea in the car audio industry... I mean, you say "unless you really know your stuff" in the same line with "unless you are buying a prefab"! The manufacturer of the prefab box DEFINITELY doesn't know my stuff (unless of course its the same manufacturer of the subs and its made for them, but I don't know of any bandpass like this, although I'm sure they exist; if that totally pre-enclosed system is what your talking about then I get what you're sayng). Anywho, I really appreciate your response man, and everybody else's. You're all really knowledgeable, and maybe some of it will rub off before real crunchtime on my build.

 

[audioholic 5,000+ posts]

Hmm well it depends on what freq you are looking for CAD. Honestly most sealed boxes and be extremely flat over a few hundred hertz which is totally pointless in my opinion. I have a bandpass that is EXTREMELY loud off 500 watts and it is almost completely flat from 38 hz to 60hz.. rap is LOUD country is LOUD. rock is LOUD. Most people think of roll off and they think a good roll of is playing rock and rap. well you can do that with about 25hz lol. Bandpass typically requires a bit of size. But if you want SQ and insane output bandpass can be your friend. Problem is bandpass is MUCH harder to design than ported and about 1000 times harder than sealed. So unless you are buying prefab or know your stuff very well don't even attempt

How can a guy with a world record have such off-base ideas about sound systems? Im getting the strong impression you dont do your own installs.
Yeah, having a flat response from a sealed enclosure for 'a couple hundred hertz' is so much worse than your flat response from 38-60hz. //content.invisioncic.com/y282845/emoticons/eyebrow.gif.fe2c18d8720fe8c7eaed347b21ea05a5.gif The scary part is, some people might actually believe your BS.

 

[vehementSPL 10+ year member]

I never said the sealed range was worse. I said in my OPINION (means for my personal listening taste) the range of a sealed is pointless. I don't see anywhere that I stated it was worse. And I designed and built mine . Thanks appreciate it though. So where exactly did I say my box had better roll off vs a sealed????..... What I was saying is mine plays almost every type of music and is about 5 times louder than a sealed box off same power

 

[audioholic 5,000+ posts]

I never said the sealed range was worse. I said in my OPINION (means for my personal listening taste) the range of a sealed is pointless. I don't see anywhere that I stated it was worse. And I designed and built mine . Thanks appreciate it though. So where exactly did I say my box had better roll off vs a sealed????..... What I was saying is mine plays almost every type of music and is about 5 times louder than a sealed box off same power

The 'range' isn't why someone would chose a sealed enclosure for anyway, its the roll off. Again I have to wonder who does your installs for you. I mean, you say you dont even understand why people go sealed, and then tout the wonder SQ virtues of your BP setup that's only flat to 38hz. And you are a MECA champion? lol

 

[vehementSPL 10+ year member]

I said in my opinion. I know why people went sealed. But if he was looking for good output then bandpass /ported is an good option. And yes I am. You know you sure talk a lot of crap on here for not having any records. bring it to the lanes . If i am so inferior to your massive brain bring it. Don't talk it. I will take a dump on you in the lanes. I will be running mod 4 or modex 2 this year. some come on. I love how you like to twist my words. I never said "bottom line" I said opinion. And I know why people use sealed. But is for sure it isn't efficient . And the reason I gave an example cause when most people think about bandpass narrowing down freq they think one note wonders. they still can be very musical. more so than ported . Just take larger box. but on the large scale of sound yes it limits it down. I am sure you will find some great reason on why you won't/cant do it. Talk is cheap. I will be in the lanes waiting. I have nothing to hide. Seems you are pretty quick to judge somebody when you took something out of context

 

[audioholic 5,000+ posts]

I said in my opinion. I know why people went sealed. But if he was looking for good output then bandpass /ported is an good option. And yes I am. You know you sure talk a lot of crap on here for not having any records. bring it to the lanes . If i am so inferior to your massive brain bring it. Don't talk it. I will take a dump on you in the lanes. I will be running mod 4 or modex 2 this year. some come on. I love how you like to twist my words. I never said "bottom line" I said opinion. And I know why people use sealed. But is for sure it isn't efficient . And the reason I gave an example cause when most people think about bandpass narrowing down freq they think one note wonders. they still can be very musical. more so than ported . Just take larger box. but on the large scale of sound yes it limits it down. I am sure you will find some great reason on why you won't/cant do it. Talk is cheap. I will be in the lanes waiting. I have nothing to hide. Seems you are pretty quick to judge somebody when you took something out of context

Putting words in your mouth? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif Your words are there for everyone to read themselves. Here, let me remind you of your great wisdom...

Honestly most sealed boxes and be extremely flat over a few hundred hertz which is totally pointless in my opinion. I have a bandpass that is EXTREMELY loud off 500 watts and it is almost completely flat from 38 hz to 60hz.

So I guess you were letting us know you think the freq response of sealed enclosures is "pointless", and yet you also said "I know why people went sealed". It doesn't take a rocket scientist to see you are talking out both sides of your mouth.
1) you were downing sealed boxes because you didnt see the point of a flat response over 'a few hundred hertz', 2) you were boasting the meager 38-60hz freq response of your BP setup as wonderful, when in reality its sub-par for most standards, simply because its louder than its sealed counterpart 3) and NOW you want us to believe you truely do understand why people do chose sealed boxes, just because I called you on it. You didn't mention the correct reason at the time, and the reason you DID mention made no sense... but sure we are suppsoe to believe you not only know what the hell you are talking about here, you're some kind of expert on the subject. Got some swamp land to sell us while you are at it? //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Please show me where I said BP boxes cannot be anything but a one-note wonder. I do not know your experience, but Im confident I was playing with BP enclosures well before you knew what the term meant. This is a discussion about SQ, and here you are stating you dont understand the choice to use sealed boxes, but oh hey BP is awesome. //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif If you had a clue what you were talking about, you wouldn't even be mentioning a sealed enclosure's flat reponse for a few hundred hertz, you'd be mentioning its roll-off pattern that closely matches common transfer functions in cars. In-car response is all that counts, and THAT is where sealed apps are superior to BP. This is a discussion about SQ and your great motive for pushing BP is its louder. Thanks for the insight.

I bring your 'MECA championship' into it merely because you seem to think that is proof enough for your hair-brained ideas on audio. It isn't. Ive been in the car audio scene most likely since before you even thought about driving, Ive never competed, and Im not about to start just to prove you dont know your *** from a speaker port. Your own words do that for you already.

You are right, talk is cheap, and some people's talk is cheaper than others. Im coming to realize yours is worthless.