does anybody see a problem

[LosIsATool 5,000+ posts]

Bump

 

[pro-rabbit 5,000+ posts]

Cliffs? I missed a lot some how..lol

 

[LosIsATool 5,000+ posts]

Cliffs? I missed a lot some how..lol

I was hoping you could take a look at my layout. I'm a bit concerned about the port and sub placement. It's a really quick sketch, the 10x25.5 is a slot port going out the back. Box is 13 inches double baffled tall. For my subs reconed to 15s.

 

[Moble Enclosurs 10+ year member]

[quote name='kushy_dreams']I do not agree with this... @Moble Enclosurs ;[/QUOTE]

Yea, loading can be an issue and if you have ran them like this all the time, as you said, CATMAN "subs close to a port have been an issue for ever and i've never had a problem. all the airspace will be used regardless", then the differences of that an a properly loaded design may not be noticed, or may be overlooked.

It is possible to get a good response from some designs where they are positioned close to the port if the port is acting as a pressure valve or much like an HVAC type air flow setup based on pressure, but the placement of the subs in other design styles becomes more important and sensitive to phase issues and can reduce peaks in a response curve. In fact, it is a great idea to do this in some SPL setups to gain efficiency in the higher bass range to match gain-just have to be careful then of excursion issues. That is the other consideration here.

The thing with ideas such as the one pictured in the beginning of the thread, is that the port will act as a pressure chamber just as much as the compression area does, so placement in that sense is not really a big issue here as long as the port is on the lower side of the recommended cross-sectional area.

You know, here is a way to look at it. THink of the box as a vehicle cabin, and think of a vehicle cabin as a box, because in reality-based on physical aspects of each, they are, and any bounding areas are, essentially the same thing, just each with different dampening and absorption coefficients. The length of a wave does not change, the speed of sound changes minimally based on other minor changes (temp, humidity, etc), but all in all, the propagation is a constant, jsut like it is in a more dense material, such as water (which is where I began my experimentation on sound propagation). In any confined space, regardless of size, reflections occur, and changes are similar to that of any finite space for boundary effects of each frequency. Its the intensity that changes the most. and the pressure fluctuations that change the most.

SO, that being said, think of this design as a blowthrough, that leaks into the trunk still. What will happen is you will get good output (if it is actually designed to do so-and not just based on limitations and tuning), but with phase issues and pressure loss at lower frequencies (not all, but at those that are not excited by the vehicle it will be installed in). The response will have obvious peaks and nulls. And again, this does not say the output will not be good, or it will not have the sound you like........you might even end up enjoying it.......but the subs may not enjoy it as much as you, and neither will the box or the electrical load on the amps. It may have huge load peaks as well, depending on tuning and such, for impedance changes.

All in all, try it. Thats what I am saying. If you dont like it, you will at least know why now. . If so, then you were meant to listen to those effects by personal preference. That is something as a designer that is hard to figure for in an acoustical sense, because some are sensitive to a few dB differences, some have different opinions in a good SQ sound (mainly in lower ELF tuning vs higher tuning) and some love the huge BP like peak in some responses and don't care of the mechanical effects that occur as long as the subs last a while, etc. SO, those types of differences are better off measured than calculated alone. This is why you will here other designers say, "real life tuning will override any calculation" and such things as that. Because in reality, they do.
SO, give it a try, if all of the figures show it will work, and report back with some results! It will help others in the long run as well on whether or not they want to do a shot in the dark install for fun and maybe give more confidence for others to blow a few bucks for something that not many others will try.

 

[RangerDangerV2 5,000+ posts]

2.8 cu ft per woofer, sep. chambers, with about 100sq inches of port tuned to about 34. thats what I think you should do.. but no one ever listens to me.

 

[mazdakid 5,000+ posts]

His port is going to take up as much space as each sub gets if he did that ranger, i doubt he has enough room for a box that big.

 

[RangerDangerV2 5,000+ posts]

His port is going to take up as much space as each sub gets if he did that ranger, i doubt he has enough room for a box that big.

then op should not do 15s if he cannot put them in the correct box. if he can find the space for my suggestion I bet it will get down.

 

[CAT MAN 5,000+ posts]

yeah derek just keep the 12s

 

[mazdakid 5,000+ posts]

Maybe keep the 12's or switch to a single 18 if you want to try something different.

 

[LosIsATool 5,000+ posts]

This is bull ****. How can I gut the entire b piller back and only fit 2 12s. Wtf

 

[CAT MAN 5,000+ posts]

This is bull ****. How can I gut the entire b piller back and only fit 2 12s. Wtf

4 10s? more cone area than 2 12s IIRC. bout 4 net cubes is all they would need

 

[LosIsATool 5,000+ posts]

4 10s? more cone area than 2 12s IIRC. bout 4 net cubes is all they would need

I cant buy more subs. Reconing was going to be cheap. I think I'm just going to try a new box with a single 6 inch flared areo

 

[CAT MAN 5,000+ posts]

I cant buy more subs. Reconing was going to be cheap. I think I'm just going to try a new box with a single 6 inch flared areo

geet dat port area in or you wont like it.

 

[LosIsATool 5,000+ posts]

geet dat port area in or you wont like it.

what did you say

 

[CAT MAN 5,000+ posts]

what did you say

been around my homies too long

do lots of port for joo d-man. lots and lots.