The 4th order thread

[Oraclem19]

its not as easy as I make it look lol. 4th orders take a good amount of work in both design and build to make them do work. I designed mine at least 20 times until I was happy

curious to build one of these, from what you say(some of the time) it is simple calculate rear chamber tune, multiply ratio for front chamber, port front chamber.

Yet with all the redesign, what is there to adjust so many times? ratio, port volume, and port size?

Just looking to get enough information to not put $800 into wood redesigning this many times. Possibly how to find what Fb to tune front chamber to and how that(as well as Fc) translate to the response range?

Not sure if you have a preferred program or if there is one. Used to use Bassbox until my license expired. Possible in Hornresp?

Not exactly trying to rule 4th orders, just trying to get Q requirements for a good 4th order woofer, and be able to make 35-55 flat(ish) response boxes. Anything on that is just a bonus.

 

[RangerDangerV2 5,000+ posts]

curious to build one of these, from what you say(some of the time) it is simple calculate rear chamber tune, multiply ratio for front chamber, port front chamber.Yet with all the redesign, what is there to adjust so many times? ratio, port volume, and port size?

Just looking to get enough information to not put $800 into wood redesigning this many times. Possibly how to find what Fb to tune front chamber to and how that(as well as Fc) translate to the response range?

Not sure if you have a preferred program or if there is one. Used to use Bassbox until my license expired. Possible in Hornresp?

Not exactly trying to rule 4th orders, just trying to get Q requirements for a good 4th order woofer, and be able to make 35-55 flat(ish) response boxes. Anything on that is just a bonus.

have you ever tested at all for spl? what I am trying to accomplish is very difficult, and so far I am succeeding. I am not building your everyday 4th order. The smallest changes with my enclosure can make huge differences. if you want a simple 4th order, then build a simple 4th order. I dont use programs, I use my mind. honestly, what you need to do, is pick a woofer, run the numbers, and see if it will model well in a 4th, I dont have a long list that I keep for 4th order friendly woofers.

 

[Oraclem19]

have you ever tested at all for spl? what I am trying to accomplish is very difficult, and so far I am succeeding. I am not building your everyday 4th order. The smallest changes with my enclosure can make huge differences. if you want a simple 4th order, then build a simple 4th order. I dont use programs, I use my mind. honestly, what you need to do, is pick a woofer, run the numbers, and see if it will model well in a 4th, I dont have a long list that I keep for 4th order friendly woofers.

Was simply wondering if it had a certain Q it likes. Like every tranmission and horns and a few other complex styles as I consider this a complex design.

Why not have your design style be an everyday design? 25hz-60hz with 2 db difference sounds pretty **** musically ideal in a daily box to me.

What numbers am I running? I only know how to calculate a Fc, and multiply it by a ratio chosen at random between 1:1 and 4:1 depending on... desired box rise(?)

Does this modeling consist of a calculation to determine spl at a certain hz, watt, and box resonance? Would love to not need a program for that.

You started this thread to ask "any" questions about 4th orders. Just trying to get enough info here so I don't need to make 20 boxes, test 10 woofers, and find someone who will loan me a TermLab 100 times to find a box that performs in the correct frequency range with the flatness I desire.

 

[RangerDangerV2 5,000+ posts]

Was simply wondering if it had a certain Q it likes. Like every tranmission and horns and a few other complex styles as I consider this a complex design.
Why not have your design style be an everyday design? 25hz-60hz with 2 db difference sounds pretty **** musically ideal in a daily box to me.

What numbers am I running? I only know how to calculate a Fc, and multiply it by a ratio chosen at random between 1:1 and 4:1 depending on... desired box rise(?)

Does this modeling consist of a calculation to determine spl at a certain hz, watt, and box resonance? Would love to not need a program for that.

You started this thread to ask "any" questions about 4th orders. Just trying to get enough info here so I don't need to make 20 boxes, test 10 woofers, and find someone who will loan me a TermLab 100 times to find a box that performs in the correct frequency range with the flatness I desire.

My design is a burp design, the goal is 150 with less than 500 watts, which im getting close to. it just happens to be very musical. Model the Fc for a given woofer, if it needs a stupidly large rear chamber, then it is not optimal, second off, if you would take the time to read, a ratio is not chosen at "random." second, any program that gives you spl calculations is going to be wrong. unless it can factor in cabin gain, tempurature, barometric pressure, electrical inductance to the coils, and efficiency of the amplifier. this is why i dont use them. If you follow the guidelines that I have layed out for a 4th order, it will have a very transient response and get loud. If you are reading this in a voice that makes me look like a jerk, then read it again. Im not very good at typing politely, so if you need help, I can help you more via PM's

 

[Oraclem19]

My design is a burp design, the goal is 150 with less than 500 watts, which im getting close to. it just happens to be very musical. Model the Fc for a given woofer, if it needs a stupidly large rear chamber, then it is not optimal, second off, if you would take the time to read, a ratio is not chosen at "random." second, any program that gives you spl calculations is going to be wrong. unless it can factor in cabin gain, tempurature, barometric pressure, electrical inductance to the coils, and efficiency of the amplifier. this is why i dont use them. If you follow the guidelines that I have layed out for a 4th order, it will have a very transient response and get loud. If you are reading this in a voice that makes me look like a jerk, then read it again. Im not very good at typing politely, so if you need help, I can help you more via PM's

Much better with first post how-tos, although I did read the whole thread a few times on occasions, My memory didn't quite serve me as I'm mixing them up with a few other ratios for horns. PMing away.

 

[mlstrass 5,000+ posts]

You won't need to build/test 20 times for a daily set up. Use a decent program and go from there as those numbers will not translate perfectly to real world application.

I just did a 4th in a Suburban with 8 15's. Port opening/tuning in the program was WAY diff then what worked best in vehicle. So that is the part you normally want to be able to play with to dial it in. So if possible design it so loading wall/port can be adjusted until your happy, then make it permanent.

One I just did is a demo set up: 57.5 @ 30Hz and 60.3 @ 40Hz, so perfect for most Decaf music. Does dropp off again at 50Hz and loading wall alone wouldn't correct that but guy is happy with it.

 

[RangerDangerV2 5,000+ posts]

You won't need to build/test 20 times for a daily set up. Use a decent program and go from there as those numbers will not translate perfectly to real world application.
I just did a 4th in a Suburban with 8 15's. Port opening/tuning in the program was WAY diff then what worked best in vehicle. So that is the part you normally want to be able to play with to dial it in. So if possible design it so loading wall/port can be adjusted until your happy, then make it permanent.

One I just did is a demo set up: 57.5 @ 30Hz and 60.3 @ 40Hz, so perfect for most Decaf music. Does dropp off again at 50Hz and loading wall alone wouldn't correct that but guy is happy with it.

we need pics yo. ill see if boland will give me some pics of his new build too, going to be easy 57's

 

[Buck 5,000+ posts]

x2 pics.

 

[RangerDangerV2 5,000+ posts]

doing 146.9's wired to .7, rising to 3ohms at about 12.5-13v. I dont have a clamp, but I know Im drawing 65.5Vac lol. but my guess is that its either at 1k, or very close + or - a 100 watts or so

 

[RangerDangerV2 5,000+ posts]

So ive been playing music, mostly higher stuff because I cut my port down, and the front chamber wont pick up the lows like it did before. and wired to .7 its averaging a 145.xx on music, which is pretty good for about 1k, but it feels like 150s on music. very very intense.

 

[2kyukon 10+ year member]

anyone wanna charge to design me a 4th for 4 18s in a blowthrough? pm me if so

 

[Buck 5,000+ posts]

Mr. Danger, what do you think about front chamber tuning frequency? I see a lot of mid to high 40's tuning, even 50, 51. What are you tuned at now?

 

[RangerDangerV2 5,000+ posts]

Mr. Danger, what do you think about front chamber tuning frequency? I see a lot of mid to high 40's tuning, even 50, 51. What are you tuned at now?

I was tuned to Fc, which is perfect for daily music/ and even some spl. makes it very flat. but I cut down my port and tuned my front to 54, which makes it peak right at 41hz, which is the resonant frequency of the tahoe. so its all application dependent really.

 

[Beatin' 10+ year member]

on the subject of building 4th's, isn't easier to build the sealed box first, then build the front chamber as a "sleeve" that slips over the sealed box? The you screw a plank of mdf on the bottom end of the sleeve that the rear of the sealed box is showing through to keep the sealed box from slipping out. You can have bolts screwed in on the sides of the sleeve so the sealed box won't go all the way forward if the entire system is sitting on its side. The small open edges on the back end of the box between the sleeve and sealed box can be stuffed with some foam or rubber to prevent air leaks.

This way you can get to the subs quicker for whatever reason, or take it apart faster and put it in a different vehicle.

 

[RangerDangerV2 5,000+ posts]

on the subject of building 4th's' date=' isn't easier to build the sealed box first, then build the front chamber as a "sleeve" that slips over the sealed box? The you screw a plank of mdf on the bottom end of the sleeve that the rear of the sealed box is showing through to keep the sealed box from slipping out. You can have bolts screwed in on the sides of the sleeve so the sealed box won't go all the way forward if the entire system is sitting on its side. The small open edges on the back end of the box between the sleeve and sealed box can be stuffed with some foam or rubber to prevent air leaks.
This way you can get to the subs quicker for whatever reason, or take it apart faster and put it in a different vehicle.[/quote']

my front baffle is removeable... I thought about that idea, but decided against it. I wouldnt do it.