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sealed Isobaric box help

5K views 25 replies 12 participants last post by  jrod666999 
#1 ·
Has anyone here ever built an isobaric box, I have always heard that you can use half the box size of 1 so I can build a box around 1.75 cuft gross for my 2 Kicker C-15 s, right?
 
#3 ·
i have never used one but i think it will be highly advised against esp with 2 15's are you hurting for room?
 
#4 ·
I've built a few of these. most recently one for my 2 LMS 4000 12's.

There are different types of isobaric enclosures, Mine was a compound isobaric. The sealed chamber behind the inside driver is 1/2 the recomended box size and then the chamber between the two drivers only needs to be big enough so they don't hit.

Isobaric enclosures are more geared for SQ and it takes both subs to get as loud as one sub would be in a regular sealed enclosure. I do love them though.



 
#7 ·
newer subs take a lot smaller boxes than say ten yrs. ago.
most folks advise against iso.
most haven't had one.

iso eliminates certain harmonics, that you CAN hear.
the subs are at least 20 years old, (Kickers that actually say Kicker on the non-inverted dust cap)

I plan on doing a face to face one in one box, and the other sticking out of the top.
 
#6 · (Edited)
I love isobarics. There are no downsides except for cost. I recently designed and built a DOUBLE compound isobaric using some cheap 8" drivers I had on hand. They sound amazing in this design! In the pic you will see that each "side" has two drivers, they are separated just enough to prevent physical contact. This can be done any way you like (front-front, back-back, front-back, etc.) and no fiberfill gets used; it must be completely airtight! You could use some sort of deadning on the walls if needed, but my boxes are always dead enough via construction/bracing.





The void (area to be computed using VAS) does get some loose fiberfill, if desired (I always use fiberfill).



My setup uses 2-ohm SVC drivers so they were wired series pairs, then the pairs in parallel. This gave me 2-ohms to my amp at the end.
 

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#9 ·
ive ran isobaric before, and absolutely loved it. only thing i dont like about iso is the cost. and ftr ivie ran isobaric in a normal size box, and it didnt surprise me, the bass still was much much deeper! alot of people say iso is only good for running an smaller box, i find this not to be true. you can still run isobaric in a normal size enclouser, and still get much more extended bass. only downfall to running iso in an normal size box is, you will reach the subs maximum xmax very quickly with very little power.
 
#10 ·
Ive heard them before and like the sound. This was on a sealed box running 4 solobarics. I am thinking about doing a isobaric 4th order with a bunch of 6.5 subs. Cutting the box down is a piece of it, but also to say I did it. Home audio guys love isos, it is usually the car guys that like bigger ported boxes that say not to do them. It will have a more tight sq sound vs. a big hit type sound.
 
#11 ·
There seems to be a few isobaric guys on here and I have a question. I am looking at 4th order isobarics and getting conflicting info. I know I cut my sealed side about half for the isobaric, but have been told different things regarding the ported side. Is it true that I would keep my port length and size on the ported side the exact same as if it was for a single driver in the 4th order? I was told to design the 4th order for one driver and just cut the sealed side in half and add my isobaric.
 
#12 ·
you are correct sir.i suggest running regular sealed side if u have the space. like i said isobaric rocks! and sounds WAYYY better in an normal size box. but if you must, half the sealed portion, and keep everything the same in the ported section.
 
#14 ·
no matter how strong an individual motor is on an particular sub today, running even that sub iso would still benefit. iso not only couple motor strength, but combine cones as well, that why iso sounds so lowwwwwww. look at it like this, if an sub sounded deeper just because of motor strength alone,then every one would go for subs with an Stupid strong motor. however that is not the cause. stronger motor itself wont change the way an sub woofer sound period. but iso does change the way the sub sound because of the added weight of the overall mms. look at any home theater ro SQ sub woofer T/S parameters. those sub have an significant increase in mms vs other sub woofers. prime example look on Fi web site, and compare the fi q's to all the other Fi drivers. the q's have an higher mms, then even the mighty btl. Sq subs always have higer mms, which makes them less efficient cause of the added weight. but this is where isobaric shines. you have double the motor strength to move that heavy mms assembly.
 
#18 ·
iso's to me always sounded tighter. Theoritically, you will lose your 3db gain you would normally see from going from 1 sub to 2. Talking about a simple sealed iso enclosure, this would be way smaller than having 2 woofers in a standard sealed box. You still really see the cone area of one woofer though. Which I think is why there is no increase in sensitivity. If I remember right, the tightness has something to do with 2 motor structures basically controlling one cone, not 100% accurate, but you get my point.
 
#20 ·
iso's to me always sounded tighter. Theoritically, you will lose your 3db gain you would normally see from going from 1 sub to 2. Talking about a simple sealed iso enclosure, this would be way smaller than having 2 woofers in a standard sealed box. You still really see the cone area of one woofer though. Which I think is why there is no increase in sensitivity. If I remember right, the tightness has something to do with 2 motor structures basically controlling one cone, not 100% accurate, but you get my point.
Yes sir your correct. You only get the cone area of one driver, and since you have two motors with a single cone area you gain control, thus it sounds alittle tighter. You don't get the 3db gain since your not 2x the cone area, its staying the same.
 
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