enclosure design in a limited space

I've got a 300ZX and have had sealed boxes in it previously.  When fired up I got a lot of hatch rattle.  I ended up making a downward firing box on small legs and that helped, but it got stolen.

I'm wanting to build a ported enclosure(s) for the Z.  I don't want to fire the driver and ports up as I had bad experiences with that as stated above. 

Please discuss advantages/disadvantages of firing the driver and ports FORWARD, REARWARD, and the driver firing into one corner of the hatch and the port(s) into the other. 

Also, what about slot-loading the driver and/or ports by having them aimed at the floor with a 1-2" gap to let the sound out into the cabin?  Good, bad?

Thanks, have looked on Google, but can't really find what I need.

Mike

munchichee, that first link only has one page and ackowledges a similar problem, but doesn't give any solutions.

I've read a lot on the second site, but I don't recall it talking about aiming of subs.

Thanks,

Mike

My favoirite box I ever owned was a 1.75 cubic foot box that was down firing with a slot port. It had a soluid lip around three sides and the fourth side was opened and aimed towards the back of the car. I had a dvc orion xtr 10 in it and it hammered. Aslong as your sub meets the requirements for downfiring i have always found this to be the best way to help eliminate hatch rattle.

Ravendarat wrote:

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 Aslong as your sub meets the requirements for downfiring

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What does that mean?  I've never heard of a requirement for downfiring, can you explain please? 

Imagine a box with the same setup you just described, but the enclosure is ported.  Could you vent BOTH the driver and the port through that slot formed by the three sides of the box with no problem?  That's what I was thinking of doing.

Thanks,

Mike

[QUOTE=stevdart]About downfiring requirements https://www.partsexpress.com/resources/downfire.html[/QUOTE]

Many thanks for that link.  I'd never heard of that issue before.

My JL10W3 looks like it comes out to about 2% so it should be fine.

Thanks again,

Mike

If you have a port that exits a box into a slot loaded configuration, does the slot length add to the tuned length of the port?  I'm talking you have a port firing downward from a box and the box has 3 "rails" holding the box up with one side open.  I can see if the slot port was the wame width and height of the outlet that it would probably affect it.  I'd guess if the slot port was significantly different in height and/or width that it might not affect the tuned length. 

Ravendarat, do you know?

Thanks,

Mike

DYohn] wrote:

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es, the configuration you describe can in effect lengthen the port and change your tuning frequency.  It will also likely create a "howling" or "tin-can" sound at whatever new (too high) tuning frequency the oversize "port" has created.  I suggest rotating your enclosure so your port does not face downwards... I assume it was not designed to face down?

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Dyohn, I don't want the sub to show, or the port either if possible.  I ran a calculation (if the sub can withstand the sag etc.) that showed the sub will be OK firing downward.

I am going to build at least one sub enclosure in a corner location, maybe both corners, haven't decided that yet.  First pic is the location in the back of my car (300ZX):

Here is a very rough sketch of what I am envisioning, and not to scale.  The port will be a slot port, but that would have been messy to draw freehand and would just have confused ppl looking at the drawing.  The point is, I have the sub and port firing downward and all the sound energy emenating from the slot:

I suppose I could have the driver firing down into the slotted area and the port firing across the hatch, would that be preferrable?

How tall should the slot be?  I'd like to use the minimum height I can, I'm using a single 10 in each enclosure.

Thanks for any input,

Mike

I'm trying to figure out a ported enclosure that will work for me. 

Below is a revised drawing.  If the baffle height is the same as the port height, and the widths are the same, can I calculate total port length as X + Y + Z or can I not have the sub firing into the port path? 

Other wise I would make the height of the baffle different than the port height, and/or a different width.  Then I guess the total port length would be just Y + Z (plus end correction per JL Audio site), correct?

How much difference in height/width does my slot-loaded outlet need to be from my port dimensions?

I've done my research, but can't find this sort of information.  I need help, please.

Mike

I am trying to figure out what subwoofer/port arrangement I want to build my enclosure with. To begin with I'll show the are that I want to use in my car (300ZX):

Below is my first concept. It is very rough and not to scale. I was considering firing the driver and the port into a slot loaded area. I can't find any information on whether I can fire the port into this area aslo, so I may have to forgo this concept.

Below is my next concept. It is very rough and not to scale either. The key concept I am trying to convey here is that the driver is firing into a slot loaded area that empties into the cabin, and the port fires into the corner of the hatch, in the gap formed by the contour of the hatch area and the sub enclosure. The area the port fires into will psuedo-slot load it I *think*.

My next idea is a combination of the two sketches. Imagine the second sketch, but with the driver outlet rotated 180 degrees and firing into the same corner gap that the port does.

Last concept is to have the driver slot loaded outlet fire into the corner as described immediately above, but have the port fire out into the cabin 180 degrees from the position it is drawn in.

I don't have any experience with these configurations, and I'll appreciate some feedback. I'm asking which configuration would be the most efficient and help me get the best low bass extension.

I have to be able to stow my T-tops still, so I don't have the luxury of of just building a big roughly square box and move it around. The enclosure has to be built into the corner as much as I can to save space, so I need to get a good idea of what I am going to do before I get down to really expending effort calcuating all my dimensions for all the wood and bracing I will need.

Thanks,

Mike

Ravendarat wrote:

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The first scetch will work fine. The only complication could be the tunning frequency of the port could be changed slightly due to it being so close to the ground. I did run a box in a vary similar design for like 2 years and had no problems, in fact it was actually my favorite box I have ever used. You should keep the driver and the port on the same face so the third Idea is also a good one.

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Do you think the corner loaded appraoch would be more efficient?  Or am I just asking for rattles by firing into a plastic lined corner?

Also, is there a formula ot rule of thumb to guestimate the height of the slot?  I think I read somewhere to use 75% + of the driver area, but I'm not sure of that, or why that was the chosen number.  Also, I think I'll radius the mouth of the slot where it opens into the car.

Thanks,

Mike