Isobaric, Isoplaner, sealed up...

[jdc753]

Hey guys look, the noob learned a new word

Well I think I am starting to get to the point of knowing enough to be dangerous but not enough to be an expert lol. While doing some research and talking with some people who actually do know what they are doing I stumbled upon a build for a Dodge ram that is very similar to what I want to do. Also in the sense of wanting to keep learning and doing new things with my truck I would love to try and build one of these enclosures for the new mags, however at the same time wanted to get opinions from those who actually know these mags before I go ahead and build it.


Ok, so for what I understand this build will be an Isoplanar box. Also for this if I understand it correctly this will allow for one sub to be put in a sealed box that is Half the recommended volume, then the second placed essentially in open air. So for carrying on (this is all hypothetical for discussion purposes.) One mag will be in a sealed volume of lets say 0.7 before sub and acoustical treatments. This sub will fire into a VERY small sealed container (essentially a baffle big enough to house 2 12" mags and tall enough so that the surround does not impact the other baffle and that is all. This tiny chamber is a coupling chamber that needs to be the absolute minimum airspace and will serve as a coupling chamber between the 2 subs. This chamber needs to be the absolute minimum airspace so as to avoid any springyness in air volume and thus sloppyness. The second mag will be mounted to the same baffle as the sealed mag and both will be sealed into the coupling chamber (most likely with plexi) however the second mag will be wired out of phase of the first mag so that they work in a push/pull configuration in the coupling chamber. This will reduce the output to only the cone area of 1 sub. The second mag will then be in a essentially free air but I will build a small I guess shroud around it to direct its output to load off the floor of the truck and towards the dash.


OK, so thats what I understand and what I hope to do. Don't be too harsh on me, I'm still trying to learn. I also tried to just keep it to the basics because much of the technical aspects I read about that are related to this design I don't totally understand. Things about reducing Fs and the such, plus I don't really understand how the sealed enclosure can be reduced in volume but like I said I am looking to learn.


I will most likely try to build a couple simple sealed boxes, one for both mags and one for a single mag but I would really like to try this isoplanar configuration as well as anything else other than sealed that I could try. I am going for an SQ sort of build with hopes of someday competing in IASCA maybe. But for now its just learning and slowly building.

Hope to hear what you guys thinks, and specifically Nick thinks.

[Electrodynamic]

Unless I'm mis-understanding something I think it's neat to see new terms made up for something that has been referred to as isobaric for years and years. Is this enclosure basically an isobaric enclosure with one driver (the driver you see) inverse mounted?

With isobaric alignments your enclosure size gets cut in half, which is one of the main benefits of an isobaric alignment. Distortion also goes way down because you have two drivers in the same tiny chamber (the chamber inbetween the two drivers) doing the exact same thing, which helps keep things more linear because the drivers help each other out over the entire stroke.

However, the major drawback is that you're dumping twice the power into and not getting the output out of a pair of drivers. You still only have one woofer's Sd.

Isobaric alignments are great for woofers that require BIG boxes. If a woofer requires 2 cubes sealed, you can now build an enclosure that is 1 ft^3 with the other woofer directly in front of it - still less than a 2 ft^3 footprint.

IMO, doing such an alignment on the Mag v4's is sorta fruitless. The way the Mag v4's sound in 1 ft^3 sealed and the amount of output you can get with a pair of them is really really good. It'd be different if the enclosure requirement was 3 ft^3, but it's a miniscule 1 ft^3. You've also got an XBL^2 speaker, so you're already beating other subwoofers to the punch (the low-distortion punch) when it comes to a linear BL "curve". IMO an isobaric alignment (or isoplanar) on a pair of Mag's isn't necessary. Sure you can do it if you want to, but I'd rather have the extra output from the second woofer since the new Mag v4's sound so good already.

PS: Thanks for posting this question. I enjoy getting the oportunity to address non-common topics. And a lot of the time, I end up reading about them and learning about them if I can't respond to them.

[jdc753]

sweet Thanks for the quick and detailed response. As I said I have just read up on it so any words were copied into my ignorant limited vocabulary lol. From what I understand about it the Isoplanar term was as a specialized isobaric enclosure where both subs are on the same plane/baffle.

Like I said I will probably try a few options. Much of the trouble is I really have a limited space to put them. Center console in my truck and I really don't want it to take up the Entire dash to rear seat sorta deal. the more minimal the enclosure the better. First I will probably build a 2 ft^3 sealed downfiring enclosure and see how it works/sounds and such. Then try it with a single mag downfiring and sealed (to limit enclosure size and make the enclosure nearly invisible. Then see about trying out this Isobaric enclosure.

I also agree about the extra output hence why I ordered 2 mags instead of just 1 and got a 1500D waiting to power em up

The build I saw for this was done by Team Audionutz and was in an crew cab Ram replacing the lower seat of the center console. For it he used 2 JBL WGTi 10's that required 1ft^3 sealed and placed the rear sub in a 0.6ft^3 box.

Plus like I said I wanna learn and try new things. Ported isn't an option and sealed just seems simple and plain. Gotta try out some deflex pads/egg crate and what not inside though to see those effects too. Still learning new things.

Here is what I have to work with.


Gutted console. I will be able to seperate the top from the bottom and raise the top 2-3" if necessary. only problem is this brings up mounting issues of securing the entire part to the truck inself.


When I made some quick generalized measurements I had about 2.15ft^3 to work with for the overall volume that the enclosure took up. I could expland it slightly but the smaller the better I am thinking. Then again talk to me in 6 months from now and I will probably be hacking up the entire truck for an all out build lol.


As I said I'm very new to doing more than just slapping together a box lol so any help is greatly appreciated. I am trying to come up with some rough autocad designs to get a better idea of the dimensions I am working with and how it will all look.

[jdc753]

This is the quick sketch I made. Its not made for the truck or anything just putting what I have in my head down to something with actual dimensions and such. When it goes in the truck there won't be many if any 90° corners.



The rear sealed portion is roughly 0.68ft^3 before sub displacement and any acoustical treatments I may add. So this will probably get a little bit bigger. The top chamber is 1" deep above the mounting ring of the sub. may get smaller, all depends on the sub excusion, plus I may shrink down the baffle size and speration of the subs to try and reduce the air volume in the coupling chamber.

Again just a very preliminary design idea. But looking to make a very solid and very dead box, so at least double 3/4" MDF all around and maybe some damplifier and egg crate foam or something on the inside portion.

[ku40]

Man I haven't heard anything about this in years. It's nice to hear about again, even if it is outdated for the majority of installs with today's woofers. But if you have 2.15 cubes to work with before wood displacement, that will only give you about 1.5 after, and only about 1.2 after 2 subwoofer displacement. So that is pretty small.

[jdc753]

yea it is. I am pretty much ready to resort to only using 1 woofer. So I won't be terribly dissapointed and all if I can't make it work. I just think it A) expand my horizons b) look cooler c) utilize my power better.

I just wanna see all my options before I just slap together some sealed box for a single sub and call it a day. Not that there is anything wrong with that.

Glad I can at least strike up some momories and conversation lol. When I was reading about the other build utilizing this setup his reasoning for using it seemed very sound and I consider myself to be in nearly the same situation. At the same time I don't wanna copy his build but think it would be cool to at the least try out.

[Electrodynamic]

Those are what you call quick sketches?! Wanna do some work for us sometime?

[jdc753]

Originally Posted by Electrodynamic

Those are what you call quick sketches?! Wanna do some work for us sometime?

Sure if ya got something for me. I do autoCad drafting at work most all day long and have cad on my home computer too. I don't have too much knowledge of autoCad 3D but I'm sure I could learn it if ya needed something done in 3D.