? about AeroPort's relation to subwoofer.

Hey everyone, I have a question I have not been able to find an answer to. I am getting all my calculations figured out for a soon to come box build and was wondering if the relation of the subwoofer to the internal flare of an aero port makes any difference?

The differences I am referring to are how close the sub is to the internal flare, I know if it is too close it can cause premature unloading of the subwoofer but I have seen countless pictures of boxs that have the port end as show in my second example. This is all given that you are following the rule that the port and flare are no closer to any internal wall or structure than the diameter of the port itself.

12" Droppin' Hz Hotel Series Sub running at 1500w
Gross airspace - 2 Cu Ft
Net airspace - 1.70 Cu Ft
4" Aero Port @ 14"
Tuned 34 - 35 hz

Example 1: Port under subwoofer, internal flare well past sub on other end of box.



Example 2: Port in middle or slightly offset lower than sub, internal flare is at least 4" away from sub.

 

I believe that, in example 2, there would be an internal baffle that isolates the rear of the driver from the port entrance. Otherwise you get air from the rear of the driver interacting directly with the port.

 

Right you would think that there would be some sort of baffle or something but all of the boxes I have seen with sub up/port to side there is nothing. Hell even Exocontralto built an Aeroport box for this exact sub and he went 6" and has the port pushed right up to the sub. To bad there isn't more information for AeroPorts out there, most of the stuff I have found is forum based and there isn't any certain answer.

 

I don't know shit about fuck when it comes to Aeroport (my only guess is that it's some bullshit pseudo-fancy marketing snake oil about air turbulence), and I also know that what others do runs contrary to what I think makes sense all the time. That wouldn't stop me from first building a box with the port on the baffle and see how that does, because that's the Build-A-Box 101 spot for it. Afterwards, maybe I'd experiment because then I'd have a control box to compare it to.

 

LMAO, You're probably right about that. I need to get the Port and lay things out but what I wanna try to do is space the port so that I can flip the box face orientation. The flares apparently are a large factor in whether you experience chuffing or not. As for the box I'm pretty sure I will have enough airspace that if I wanted to try with and without a baffle I could. Guess I am just gonna have to experiment.

I found this build last night that an engineer built for his car and he said it sounded good and had extremely good output. This is basically what am going to be putting together but it will be in a Rav4.

 

If the intent is to make a bass reflex enclosure, having the port at 90 degrees makes the port output interaction with the driver output a strong function of the angle of surface the side port interacts with. This literally makes phasing undetermined with such a design. For auto audio subwoofers, I prefer orienting the port out the front baffle and having the port being tuned at some low freq Fl which is below Fs of the driver. Then the 180 deg phase shift due to port/driver mismatch cancels the fact the backside is already inverted and you have matched phase, fully-determined constructive interference between the freqs Fs and Fl. The Klipsch Cornwall speaker box is a good example of this. The design above looks like more effort was invested to design for fit in a particular space more than optimal response. As mentioned above, in the above image (port 90 to and aimed at driver), without a baffle the port is somewhat defeated. Sure this will work, but it is not 'designed' if that is what you are looking for. The design intent is to have the speaker interact with the box vol, the the box vol interacts with the port as a separate filtering mechanism.

Sorry if this is redundant, that design shown directly above begs for comment.

 

Thank you for the reply, I need to re-read what you said a few times to try and grasp it so I will sort of explain what I am going for.

2018 Rav4 - It is my sisters car and she has a very strict area to keep the box in because A) She want's easy access to her spare tire and B) She want's the box easily removable as she uses the cargo area frequently for work. Originally I was going to opt for a sealed cube but after installing my system in the Tacoma we both decided to go for ported to maximize output. We are shooting for louder output than her previous system I did (12" Kicker L7 in their large ported box), she really likes Bobby Gately boxs but they are just too big for what we want to achieve so I started looking for alternative and came across the AeroPort. Everything I have read thus far says in a SUV type vehicle Sub back, Port side gives the best output but I want to go sub up since she does have stuff in the back often. The problem with having the port on the front baffle is length, it would require me to 90 internally and a few post's I have seen of people doing this the output was garbage.

Basically you answered my question I think, I need to figure in a baffle and I need to figure out how that baffle needs to be oriented and see if I can make it work in 14x14x24"

 

These are solid geometries that fit your size reqs.

The thinner a rectangular port is, the less smearing (dispersion) will occur at the 90 deg bend. Either of these designs are immensely better than that one with the tube aimed at the driver. If you use a rectangular port, just match its cross-sectional area to that of a tube if you use a calculator that assumes a tube.

As for various forums saying different designs are best, it probably comes down to what criteria they are emphasizing. At the end of the day, speaker design is all about phasing. Certain arrangements give phase reversals, and time delays and sometimes comb filtering become important in car setups. You want to take advantage of that to get the response you want.