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4th Order various ratios and sizes???

22K views 16 replies 9 participants last post by  FLAstrongman 
#1 ·
1:1, 2:1, 3:1

Ive seen this mention concerning 4th orders a few times, but can anyone explain the pros and cons of the various Ratios concerning 4th and only 4th order bandpass boxes?

From what ive read, in general keep the sealed section small, and make the ported section as large as possible, but ive seen a few small builds that worked quite well with the 1:1 ratio. I always tried to stick with the 2:1 and the 3:1 was usually out of the question because of space limits.

A 1:1 ratio would open up more possibilities for me as far as down the road for a bigger build.

Any suggestions would be appreciated thanks.
 
#2 · (Edited)
Generally, the larger the front chamber is in relation to the rear chamber, the more efficient the enclosure is.

In many of the 4th orders I've graphed, according to those graphs with a 1:1 sealed to ported the output wasnt quite as good, but the frequency response was smoother/flatter

Then again...this is just according to my little program...
 
#4 ·
I am basically at 10:1 right now and I have nice extension down to 20 hz maybe lower but I dont have a tone that plays any lower so who knows.

3:1 is the goal I am shooting for to play most everything under the sun.
 
#8 ·
1:1 tends to show up alot for flat response as said before


anything besides flat is a guessing game... u could get a chit ton of gain at 2-3notes but it could fall off very fast on both sides... so it all depends on what the goal is too, burping or daily

worst of all is that most off the time u dont hear the subwoofer start struggling since its inside and noises can be filtered out by the port... so playing far outside of the bandwidth designed can cause some damage
 
#9 ·
1:1 tends to show up alot for flat response as said before


anything besides flat is a guessing game... u could get a chit ton of gain at 2-3notes but it could fall off very fast on both sides... so it all depends on what the goal is too, burping or daily

worst of all is that most off the time u dont hear the subwoofer start struggling since its inside and noises can be filtered out by the port... so playing far outside of the bandwidth designed can cause some damage
**** it, it's a 4th order. You're not a man unless you run with the SSF off :)
 
#15 ·
Interested to get some more input on this. Really though, how many people handing out info on 4th orders actually know from experience? And I'm not talking about what you heard in someone's car. I mean how many of you have actually built several 4th orders to test what works better?
 
#16 ·
im going by bbp and winisd, ive honestly never ran across a fourth order requiring a 6:1 ratio

hell sometimes the ported chamber is a bit smaller, it all depends on the parameters of the sub, u cannot create some magical ratio that applies to any speaker ever made

thats retarded if people think that

example on winisd:
sa12 - .6sealed, 1.1ported, 43hz
hdc318 - 1.6, 2.8, 48hz
tc3k - 1, 1.2, 45hz


granted these are theoretical, but u can see there is no golden rule that applies to all three
 
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