4th order bandpass ???

[FoRgIvEn 0]

Im thanking of putting 3 SA-15s in a 4th order wall and ive read around and some say a 2:1 ratio and some say 3:1 ratio and to tune port side highh 45+- i know it changes from vehicle2vehicle and power

but what is the best place to start?

and any ideas on what size it might need to be? (for a rufe estament)

[///M5 2,833]

Yikes. Where ever you read the:

Im thanking of putting 3 SA-15s in a 4th order wall and ive read around and some say a 2:1 ratio and some say 3:1 ratio and to tune port side highh 45+- i know it changes from vehicle2vehicle and power

but what is the best place to start?

and any ideas on what size it might need to be? (for a rufe estament)

stop reading as they are idiots.

The real question is why a 4th order BP. Basically there is one valid reason why and a bunch of dumbasses that ignore it and have sub par results but since it is theirs like it and are verbal on forums. In general it is not a good alignment although like everything in audio it has it's place.

[alain 6]

@M5 the one valid reason would be?

[///M5 2,833]

@M5 the one valid reason would be?

The beauty of a bandpass is to be a box you can put somewhere else where the music isn't being played. The mechanical filter can be of benefit although electronics are rather cheap these days.

[alain 6]

And for a car audio application is their any pro's.

[///M5 2,833]

I listed the "pro" above. If it isn't part of the installation plan, the alignment usually makes no sense.

[orlando144 20]

So badically if your build doesnt call for a 4th order banpass.. It isnt necessary?

[ricksi30 923]

So badically if your build doesnt call for a 4th order banpass.. It isnt necessary?

Yes, as M5 said if you don't need the enclosure in a separate area it is most likely not a good option. An example would be in a bass trap of a trunk an option is a bandpass ported through the ski hole.

[///M5 2,833]

Plenty of negatives as well. They make good fart cannons.

[alain 6]

i guess to your stadards its not nessasery and sound bad but why have i seen so many builds with walled 4th ordered bandpasss. i live on an island and this forum all ive got just trying to be different. never heared a 4th order bp before other than 2 10in jensen sub in a prefab box with the plexi glass back in the 90s that sounded pretty good for a pair of 10's.

[ricksi30 923]

i guess to your stadards its not nessasery and sound bad but why have i seen so many builds with walled 4th ordered bandpasss.

I see a lot of people running prefab enclosures too....

[///M5 2,833]

i guess to your stadards its not nessasery and sound bad but why have i seen so many builds with walled 4th ordered bandpasss. i live on an island and this forum all ive got just trying to be different. never heared a 4th order bp before other than 2 10in jensen sub in a prefab box with the plexi glass back in the 90s that sounded pretty good for a pair of 10's.

If you want to be different so bad that you can accept something that is worse then carry on. I seriously don't understand the mentality but it has sunk in where the IQ is superficial so if that is your thing...

[EPerez 236]

Why not go with a very well designed ported box and be different by having a correct setup?

[ssh 924]

i guess to your stadards its not nessasery and sound bad but why have i seen so many builds with walled 4th ordered bandpasss. i live on an island and this forum all ive got just trying to be different. never heared a 4th order bp before other than 2 10in jensen sub in a prefab box with the plexi glass back in the 90s that sounded pretty good for a pair of 10's.

If enough people tell you the earth is flat will you eventually believe it, or continue to refute it? Something done by the masses doesn't always mean it's right, correct, or better.

For whatever reason there seems to be a huge influx of people believing 4th order ported bandpass enclosures are the key to loudness. One could argue: "But I've seen so many loud setups with such enclosures, so how do you explain that?" It's simple, when you put that many drivers together with that much power it's pretty much going to be loud no matter what, you have to seriously and more than likely purposefully fuck something up in the design big time to alter that. Now the kicker is that out of most of those installs if they had simply used a ported enclosure they could have ended up with more output on average with more bandwidth to boot.

[16K 159]

Ive heard 4th order bp is better for the lows than a normal ported box..

Anyone know why twistedchild is running a 4th order and not a normal flat wall?

[dbsupra 69]

As with anything it depends on the design and install.

A bp design depends on not only the size of the sealed section but also what ratio ported to sealed as well as port area and tuning. It's easy to screw it up and not all subs are bp friendly.

Basically the higher the ratio the more efficient but at the expense of frequency response. You can easily build something that is a one note wonder or sound like crap or both.

But I think with the proper sub and design and goals it has a place.

[orlando144 20]

As with anything it depends on the design and install.

A bp design depends on not only the size of the sealed section but also what ratio ported to sealed as well as port area and tuning. It's easy to screw it up and not all subs are bp friendly.

Basically the higher the ratio the more efficient but at the expense of frequency response. You can easily build something that is a one note wonder or sound like crap or both.

But I think with the proper sub and design and goals it has a place.

What do you mean by bigger ratio? 1/2 1/1.5 1/3?

[///M5 2,833]

Ive heard 4th order bp is better for the lows than a normal ported box..

Anyone know why twistedchild is running a 4th order and not a normal flat wall?

You've heard wrong. He's running them to be different, because he was misled, or because he is confused. Same with pretty much 99% of people running them.

[jonbearsmt 919]

WAIT THE EARTH IS NOT FLAT!!!???

[16K 159]

Ive heard 4th order bp is better for the lows than a normal ported box..

Anyone know why twistedchild is running a 4th order and not a normal flat wall?

You've heard wrong. He's running them to be different, because he was misled, or because he is confused. Same with pretty much 99% of people running them.

Lol thanks for clearin that up

[ricksi30 923]

Ive heard 4th order bp is better for the lows than a normal ported box..

Anyone know why twistedchild is running a 4th order and not a normal flat wall?

You've heard wrong. He's running them to be different, because he was misled, or because he is confused. Same with pretty much 99% of people running them.

Lol thanks for clearin that up

Yeah I agree, just because certain people look up to him does not mean that he knows what he is doing. He also has random PA speakers firing out of his back doors/windows.....does that sound like a good idea lol?

[benz280se 0]

well since you guys have ranted and raved enough about people not knowing what they are doing and basically saying that people running bandpass boxes are dumb;can somebody find it in them to answer the question at hand?

running a bandpass or a regular box or a woofer stuffed in a trash can and sealed with elmers glue is a matter of choice if you can help the person with the choice that he/she has made with thier intended woofer then do so if not just shut up and let people who are ready to help do so without feeling like they are going to get burned . i have a mercedes 560sec and the gas tank sits behind the rear seat and takes alot of the rear deck space, a bandpass box served me quite well for two ssd's ported through the deck. even though i know now that the box was designed backwards and put together solely with staples (i paid 300 for that mess) but it still pounded like a mutha. anything from about 60-20hz was beast. i wish i could help but i dont know the measurements , maybe someone will step up and help. and before you guys go at me i have tried several different boxes in this trunk. box facing rear port up (trash), round ports facing backwards and slot port facing backwards.-both sounded decent but my trunk lock and the rear lights cant handle all that pressure and my trunk lock broke and had to modify it. also and my rear lights keep blowing because of the massive vibrations. and i do have dynamat and foam in the nooks and crannies of mytrunk.

Edited January 17, 2013 by benz280se

[Quentin Jarrell 671]

Your very application is the ONLY reason to EVER use bandpass enclosure.

This is a forum for audio enthusiasts, for people who enjoy not only their systems but who enjoy having knowledge about their systems. Your not going to see anyone here go in depth of why and when to use what type of enclosure because someone asks the same question every week.

One of the most basic parts about a system is frequency responce. All it takes is basic knowledge which can be found from any number of sources (loudspeaker cookbook prime example) to understand this. This knowledge along with the ability to read a graph and it is very easy to see why not to use a bandpass enclosure when a ported enclosure will fit the application.

Besides M5 explained why in one of his very firsts posts. You or the OP may not have understood his wording but again it was basic terms used in system design and all it would have took was 10 minutes on google and it would be clear why it's never better to use a bandpass enclosure in a wall over a ported enclosure for a daily system.

[///M5 2,833]

i have a mercedes 560sec and the gas tank sits behind the rear seat and takes alot of the rear deck space, a bandpass box served me quite well for two ssd's ported through the deck. even though i know now that the box was designed backwards and put together solely with staples (i paid 300 for that mess) but it still pounded like a mutha.

Ding, ding, ding

The beauty of a bandpass is to be a box you can put somewhere else where the music isn't being played.

I know Quentin pointed out that is exactly what I said, but I thought I'd highlight it. It is EXACTLY what we would have recommended for you although designing it backwards I wouldn't recommend. Could easily improve your results with a forward design.

Why don't we do this the other way. I gave the reason and a half where it fits as an enclosure. We can sure use this thread to discuss where else someone thinks it fits in car audio. Outside of car audio there are plenty of reasons, but the name of the enclosure describes those perfectly. Within a car your application is the good one, the rest I've seen are based on misconceptions and limited levels of experience.

[dbsupra 69]

Since you asked I'll tell you where it fits in for me.

I'm getting ready to design and build a c pillar wall in my land cruiser. Currently I have 1 18 in a ported enclosure on a 2k amp. I like the sound and response but I want more output. I am upgrading to 2 18s and a second 2k. The problems are currently the sliding side windows are vibrating badly. Enough that it is audible and worse one is starting to leak a little when driving in heavy rain. Secondly the area I want to build in limits my enclosure space so up is the only way to go. Sure I could fit a larger ported enclosure but the side windows would be even worse. I tried a ported wall with the current equipment and did not like the sound. Next option is a 4th order bandpass. It will seal off from my sliding windows and will allow me more space since im building up. The reason I decided to try this was because I think I wasnt getting any loading with the ported wall. The mid 40's were louder but it rolled off steep below 35hz.

Maybe this will not be what im looking for either. But I wont know until I try. I like experimenting with new things. Some have had positive results. Some have not. No feelings hurt. Learned a few things along the way and worst case is some time and wood.