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4th order

 

New member
Username: Stilzz

Post Number: 1
Registered: Feb-07
I recently had someone build me a 4th order bandpass box to go in my Benz s430. The main reason was because it was very hard to get bass out of the trunk and into the car. I even have a subwoofer hole on the deck and still it wont come. I am truly amazed at this box. It is definitely the best enclosure I have ever had. If you ever decide to get a one done you absolutely must get the manufacture to design one for you with respect to the spec of your car space and speakers of course. I recently purchased a pair of RE SEX 12s awesome speakers 18mm xmax one way. The main reason why I am in love with bandpass now is because I never knew what imagining was til I got it. I am running some diamond audio hex 6.5 in front doors with some LPG 25nfa tweets and I truly can see and feel the music coming from my front window like the performance is on a stage. I did not know bass can change the imaging of you mids so drastically. You cannot judge mids and tweets unless you bass image is right. My speakers sound 10 times better than with a traditional ported box. A band pass box sounds like your standing outside a nyc night club. Sounds like thunder the roll off is very smooth and slow it sounds weird by itself but when you mix it with your mids and highs you feel submerged in bass. Sounds like playing music at a lower volume and everything is clear and the bass just pushes through. IDK hard to explain. In my opinion far more superior than ported or sealed boxes. Kick drums sound like Thunder. Great Mid bass and bandpass are a perfect combo. If you have great set of components the mid bass sounds like a sealed box. If you tune it low it gets louder on the low notes which is kinda cool. Most boxes fade away on low notes this one gets louder. So its not really a flat response. My curve looks like this it is flat between 50hz and 100hz it rolls off rather quickly on both ends of the spectrum. To my ears it sounds perfect. It can play all the notes on a Bass Mechanic cd with authority. The high bass notes are pleasant not boomy. Its boomy on the low notes. Definitely the loudest and clearest box I have every had. Sounds like you are at concert in my car. Best way I can describe the sound "Delicate sounds of Thunder" Its awesome you should try it out. The box turned out to be 4cu and change not too big like some people think.
 

Platinum Member
Username: Glasswolf

Post Number: 14035
Registered: Dec-03
I smell a troll.

7/10 on this attempt, though.
good work.
 

New member
Username: Stilzz

Post Number: 2
Registered: Feb-07
I'll post some pics soon if I can. I need a good subsonic filter my MMATS dhc2200.1 doesnt come with anything but power. I am running 1100 watts per sub. I hope I dont blow the subs. I know I drawing over 150 amps of current because I just popped that fuse. I had to put a 250a on it. Does anyone recommend a good subsonic filter. Still breaking in the subs have no clue how loud it can really go. I heard bandpasses have a threshold.
 

Platinum Member
Username: Glasswolf

Post Number: 14042
Registered: Dec-03
If by chance, you're being serious, then yes a 4th order box is alright, but it has pros and cons, like any design.
The more gain you get from a 4th order box, the more peaky the box becomes, and the higher it has to be tuned, yielding a boomy midbass response from the box at it's highest output, which is fine if you want it for SPL and aim to tune close to the transfer function of the vehicle's cabin. If you tune a 4th order box lower to make it more musical, you get a flatter response with less gain. The result is essentially just using more space to do the same job as a sealed box would do, per haps with a slight bump in efficiency.
A 4th order box will roll off quickly because it should be band-pass filtered at both ends to avoid the driver unloading. It will also be clean because 4th order bandpass boxes mask harmonic distortion as a function of their design. Generally though, I'm not a fan of 4th order enclosures in general, as most times you can accomplish the same result using a ported enclosure, with less materials, and less cost.

you'll want a 4th order (24dB/octave) high-pass filter for that box @ the tuned port frequency of the box. That being said, you need to find out what that box was tuned to when it was built. You can build a filter yourself. The diagrams for doing so are all on www.the12volt.com Just a matter of coils and capacitors and a bit of soldering.

Unless you have an alternator in your car that puts out 200+ Amperes, you are not drawing 150A with your amplifier, though. If the fuse blew, it was probably due to thermal overload, and the amplifier clipping severely from the lack of clean current to power it with a stock alternator.
 

New member
Username: Stilzz

Post Number: 3
Registered: Feb-07
Your probably right about the fuse. As far being serious. Eh it a matter of opinion. For my purposes its perfect for me. I listen to all kinds of music classical music i never hear any subs. Contemporary Jazz all I hear is the kick drum. My mids and highs make all the music my subs just compliment them. I was expecting a one note wonder box. My box plays the spectrum. The main thing I like about the box or it could be the speakers or both is that my 12s sound like 18s I am shock to hear some of the low notes that come out of it. I was runnign a fi btl 18 and these sound better. My box was only 4cu that cound have been an issue. The btl was showing .8 ohms and my amp did not like that. I am also running an AudioControl eqs

The bass is also clearer than a ported box. It sounds like a home theater in my car. Some people may not like that sound. I do. Mind you this is a custom built box designed by RE with RE speakers. I think ported sound better than sealed and band pass sounds better than ported. I am backwards huh? Just my opinion
 

Platinum Member
Username: Glasswolf

Post Number: 14063
Registered: Dec-03
well, yeah part of the problem with that 18 was that the box was too small, and it was severely underpowered. The 18 would have done much better with a proper installation. I'm using a single Fi Q18, sealed, and it does outstandingly well with 1200WRMS.

The thing is, you can't stereotype an enclosure like that. I can build a 4th order box that ranges from pretty much flat response, to extremely peaky but with about 48dB of gain. I can do a sealed box that's boomy and loud, or tight and detailed. I can even do a sealed aperiodic enclosure that's the cleanest sounding box you'll ever hear. Ported is the same way. You can build a smaller box that's tuned high and it'll be boomy. I've seen a 15" sub in a 12 cubic foot box tuned to 12Hz that you can't even hear at 40Hz, but in a home, below that frequency, it'll shake the foundation of the house apart on 2000 watts of power from a Behringer EP4000 amp. Box design is as important as the choice of box order. Most subs really should also be equalized with a 1/3 octave or parametric EQ if you want a tailored response from them, since very few boxes are "perfect" in their given environment without a bit of tweaking to the source signal.

I like sealed and aperiodic, or transmission line when it comes to tight, accurate, deep response. bandpass rolls off higher, but as you said, that is just my personal taste. HT subs also really depend on the sub. Klipsch for example, makes one-note wonder home subs, whereas you could look at SVS, or Krell, or Sunfire and get a much more detailed, more musical sub.
Personally I'm working on building a pair of sealed cubes for two Fi Q15 subs for my home theater right now.
 

Gold Member
Username: Southernrebel

Monroe, Louisiana Team Audible...

Post Number: 8334
Registered: Mar-04
I have not read/digested this whole thread, but there is one 'common' thing I have seen w/ alot of reality 4th order builds I have seen online.

I have seen 1:2 or even 1:3 sealed to ported ratios. From the experience I have, doing so can create high SPL gains. But, you can kill any attempt at flat response. It can create huge gains in SPL around the ported chamber Fs, but roll off can be horrible. I have seen big builds w/ subs that have no reason to be in a 4th order alignment....many of them lend themselves more to a ported or 6th order.

4th order can be great for SPL....as the sealed chamber helps to control cone movement.

One sub I've had alot of hands-on experience with is the DD2500. For flat (and higher spl) enclosures, they like more along the lines of 2:1 sealed to ported ratios. This will all depend on vehicle resonance of coarse.
 

New member
Username: Canaanwhite

Monroe, Louisiana USA

Post Number: 6
Registered: Nov-10
in other words your box is all wrong
 

New member
Username: Makinblak

Post Number: 7
Registered: Oct-10
I don't want to change the direction of this thread too much, but what's the difference in 4th order and 6th order? Are there any other variations?
 

Platinum Member
Username: Glasswolf

Post Number: 14066
Registered: Dec-03
2nd, 3rd, 8th, etc.. sure there are others.
6th would be where both chambers are vented. Difficult to tune, and if the calculations/volumes are off by just a bit, the sub unloads, and you're picking pieces of the driver off the inside of the box after applying power. Benefits are tremendous amounts of gain at the tuned frequency when built right, masking of harmonic distortion, and increased power handling. Cons, hard to build, large space required, one-note wonder boxes. Good for SPL only, not for music.

http://www.diysubwoofers.org/
 

New member
Username: Stilzz

Post Number: 4
Registered: Feb-07
(Glasswolf) The box was 4.5 cu including displacement. Specs for Fi is 5-10cu. I have a 150 amp alternator a Kintetic 2400 battery Batcap 300 Mmats 2200.1 I was smelling voice coils on the btl 18 That mmats amp will put out 2500 watts. The btl I have is old one with no options 14.4 volts electrical.


I was listening to the system today I am still breaking in the speakers. I was listening to the system on some Contemporary Jazz I am still satisfied. It sounds like an amphitheater. The subs play the kick drum and the bass guitar rather smoothly I cannot find a discrepancy. The louder I play it the detail you hear from the REs The tones become more separated in the bass guitar. Sealed boxes to me are clear but when they hit they hit you in the center of your chest. Ported boxes are clear but when hit you feel it on the edge of your arms. Bandpass on the other hand it feel like you have on the old school big Synheiser Headphones. The bass is all encompassing like it is in your head. You dont know it is coming from your trunk. Very wide and deep sounding. It makes the best image for my sound stage. I tried to get rear speakers because my car is so big and I want my passengers to hear music. Fugem that is the worse possible investment I made totally screwed up the image. So I turn them all the way down on the Audicontrol.
 

New member
Username: Stilzz

Post Number: 5
Registered: Feb-07
A little history. The problem with the car is that it is hard to get sound into the cabin. It has a gas tank behind the seat and tons of metal. I started out running 2 cadence wild beast 10s @ 1 ohm 2500 watts in a Probox. Problem here is the Probox was too small. Those wild beast took the power like a champ. The speakers got very hot they were gonna blow eventually. Took those out and went with Old school PG XMAX 12s @ 2 ohms 1400 watts same amp (mmats) in a sealed enclosure. First time ever hearing those xmaxes shine Very clear very deep louder than the wild beast but not loud enough for me. Took those out and went with he Fi BTL 18 @ 1 ohm 2500 watts it sounded better than the 12s I could not actually hear how loud that btl could go because I started smelling voice coils. I did not want to blow the speaker. It was jumpin pretty hard though. Next I went to a wave box enclosure with a MMATS p3.0 15 at 2ohms very clear but did not hit lows like I wanted and could not take 1400 watts and blew. Like it was fire in my trunk. And now this box. I wanted to get the RE SX 12s but could not afford. I had to settle for the SEX 12s I meant to get the 2 ohm duals but got the 4ohm duals so I am running at 1 ohm. I am afraid they are gonna blow at 1100 watts a piece unrated power. I was smelling voice coils for a second on Bass Mechanic. So I am still breaking them in. my next step is to cut a perfect hole in rear deck and send the port straight through that. The current port is 10inch round and the air is not going through properly. So I have the port facing the rear and it sounds good for now
 

Platinum Member
Username: Glasswolf

Post Number: 14075
Registered: Dec-03
What lads you to believe it was the voice coil you smelled?
Often times, a new sub, while breaking in, will produce an odd odor caused by the adhesives used in the motor structure heating up and curing. It's not really damaging anything, it just happens.
 

New member
Username: Stilzz

Post Number: 6
Registered: Feb-07
All my speakers have been used except for the new REs. When the mmats 3.0 blew it was a familiar smell and it last for days in your car. Wen I start smelling them i usually turn the volume down
 

New member
Username: Stilzz

Post Number: 7
Registered: Feb-07
Also i am leaving out that I think the btl was damaged I think one of the tinsel leads had a problem because at high volumes it would cut out. I know it is the speakers and not the amp because the REs are running fine at that ohm level. So I cant really tell you how loud that btl could really get. I will proabably get rid of it. I am RE fan now. They just cost too much
 

Platinum Member
Username: Glasswolf

Post Number: 14085
Registered: Dec-03
ah.
typically if you blow a sub, its from one of two things.
a lack of current from the charging system causing the amplifier to clip, or the gain on teh amp being set too high, causing the input stage of teh amp to clip, both of which cause thermal damage to the speaker coils.
It's rarely from too much clean power.
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