3 way subwoofer

mantha3

Member
2010-10-18 6:20 pm
Right now I have 2 subwoofers. I built a JBL 4645 that has the 18" 2242H from JBL. I'll call this the Mid Range sub woofer. What it does it does well but it does not perform too well under the 25Hz. I then have a subwoofer I built with a 12" Morel in a 4.5 cu foot ported box . I'll call this the tweeter subwoofer. The combo of these two ported subs is nice as far as what I'm hearing.

What would work well in combo with these 2 for the low end? Something that I could run 35Hz down or something...
 

Etocynned

Member
2011-12-17 1:42 am
your looking for a large long throw driver in a long tapped pipe/tapped horn. probably going to be over 4 cu m, perhaps a 2.5 m long horn.

Why a tapped pipe/horn? Driver control and predictability. you will need a high pass at the low end.

Seen lots of threads with these designs extending into the teens.

Keep seeing that if you want deep bass recovery you need the following:

1. low fs, cutoff around .6 x fs
2. strong motor, gotta push a long heavy column of air
3. strong cone, gotta push a long column of air
4. huge xmax, don't want this driver to bottom and self destruct at low frequencies, long wavelengths( 15 hz is 22.9m long)
5. big power, see 2,3,4 above, but also you need to push over 100db to hear at 20hz as you do at 40hz.

All you lurkers feel free to rip my post apart as its just dragged up from my memory of lurking on hundereds of other topics.

Btw, you have asked a question that polarizes this forum endlessly, it occurs to me that theres a reason most horns are cutoff around 30-35 hz, below that thing become so subjective with perception and the limits of equipment that its hard to be declared absolutly right or wrong in your point of view.

Yet, this is where the hobby gets fun!
 

OscarS

Member
2011-01-02 10:44 pm
why bother with all that complexity? Just get two of these and place them in an appropriate vented enclosure

images
 
having multiple subs in room is definitely improvement over one sub, no doubt about it...
but using 3 subs does not clasify as 3-way sub, in order to have 3-way sub, one would have to take 20-160 Hz range and split it to 3 regions and feed each sub with different fr range
I doubt thats what mantha3 has in mind, hence I was just pointing out that title is misleading
 

mantha3

Member
2010-10-18 6:20 pm
It is misleading...

I would just have 3 ported subs... I think what I have is primarily lacking some lower end

I have a 4.5 cu foot box ported running a Morel Ultimate UW 1258 12" Subwoofer
Then I have the new sub I built with the JBL 2242. I have a pretty big room and I think I could build someting with the lower end in mind. I'd probably do a ported box to keep with what I have now.
 
mantha3, have you thought about the option that you may need to place the subs better? very important for subs response is placement...are you aware of placement study where you put the sub in your listening position and measure fr response in various places of the room? the best fr response indicates where the sub should be placed
may be after very carefull placement, you may no need additional sub...
just a suggestion
 
I have... Not ideal where they are now. I was thinking long term of a sub that handles the low end well and having that to the rear of the room perhaps...
The problem with having three ported subs of different tuning is the phase response of each will be different, and therefore may not combine well, and the tuning (Fb) must be as low as what you want to reproduce.

If you build a third sub with a Fb of say 20 Hz, the other two will be "flapping" down that low.
 

OscarS

Member
2011-01-02 10:44 pm
the title of this thread is misleading
you are using multiple heavily overlaping subs, this in no way qualifies as multi-way sub
I have seen commercial 2-way subs, but not 3-way
that is nonsense

non-sense it is. Too much pipe-dreaming going on here unless you're running some super duper top-notch state-of-the-art sound system that would actually require something of this magnitude, a pair of high-quality subwoofers like the TC sounds units would be more than adequate to handle pretty much anything. Doesn't even have to be those that I linked to, for they make a wide range of sizes.
 

turbodawg

Member
2004-02-13 12:51 am
You should be able to replace both subs with a single large bass reflex design to cover around 15-18hz up to 150-200 hz without any problems. Dual 15's or a single low tuned 18" or 21" should be great. Having an EQ on the sub and enough headroom to use it is very important, as well as time alignment with your mains.
 

mantha3

Member
2010-10-18 6:20 pm
No chance are these going anyplace. Love these things big time and the sound is something special. The Morel I could see moving to the rear of the room but that JBL 2242 sub is staying put. Every time I listen to that thing it sounds better to me. If I could find someting to complement it in the lower hZ range I'd toy with the idea. I don't know if I'll bother with anything. This is my centerpiece subwoofer in my mind. If adding a sub with another make / model is not ideal then another 2242 sub perhaps down the road.

Thanks all and sorry for the randomness of this thread.
 

turbodawg

Member
2004-02-13 12:51 am
No idea if you're using a crossover on not on this setup..............?

Anyway, you should be fine with a 4645 alone if you install a longer port or smaller diameter port (with flares) to decrease tuning to about 18-20hz, then use a proper processor with highpass and lowpass filters, and an equalizer to tune it in as needed.

You are doing something VERY wrong if you think you need 3 subs.
 

OscarS

Member
2011-01-02 10:44 pm
No chance are these going anyplace. Love these things big time and the sound is something special. The Morel I could see moving to the rear of the room but that JBL 2242 sub is staying put. Every time I listen to that thing it sounds better to me. If I could find someting to complement it in the lower hZ range I'd toy with the idea. I don't know if I'll bother with anything. This is my centerpiece subwoofer in my mind. If adding a sub with another make / model is not ideal then another 2242 sub perhaps down the road.

Thanks all and sorry for the randomness of this thread.

I agree that JBL subwoofers sound fantastic for the most part, but you just simply picked the wrong driver for your requirements---it doesn't have the linear excursion to get down to where you want it to go without having to sacrifice something in the process. If you want to keep it JBL-brand, there is one pro-audio JBL (2269 I think) that does have much increased excursion, and utilizes a Differential Drive motor which likely has even less distortion than a 2242.
 
It is misleading...

I would just have 3 ported subs... I think what I have is primarily lacking some lower end

I have a 4.5 cu foot box ported running a Morel Ultimate UW 1258 12" Subwoofer
YOU HAVE SOMETHING WRONG.
Your woofer goes down in frequency to 10/12Hz if properly tunned in the right box (int. volume), at the trade of compared low sensitivity. A bad tunned box ported system can be the problem for the low extension or lower F3 than it should (higher tunning) with consequent low freq. extension. Check your internal (vol.) total without the vent volume+driver volume+wood thickness of all the parts that are inside. Tunned port should be equal to or lower than 20Hz for nice smooth low extension.
MOREL UW 1258
Another driver with more 5dB's sensitivity than the Morel
Scanspeak 32W/4878T00

All this drivers are machines for lower than 20Hz extensions so what you have is a lot of talk, playing outside or difficult sized/shaped auditorium, amplification is not enough for the woofers or tunning.
You need amps power (minimum) Pmin=400.0 W in 7/8 Ohm for the Morel and 3/4 Ohm for the SS.
How much is the amp you are using with the driver.
 
As adason said position or the nulls/phase of the speakers/drivers might have something to do. I don't believe you need more low frequencies, you might have it ill balanced with the fullrange speakers. Please have it addressed in a way you/we can follow, checking (problems) one by one. I think some of them you mention already, like areas/height.
How much W is the amp you are using with your driver?