Underseat SWS-8 Spacers

[pzanity]

Okay, I\'m about to grab a pair of SWS EQ\'s.

What\'s the easiest way to mount these under the seats? I understand we must have a spacer in the current enclosures? What\'s the best thing to use as a spacer? I saw a photo a while ago and someone was using some kind of foam? Whats it called?

Anyone selling spacers also? Cheers

[taibanl]

The most popular spacers are made by user JtSherri but he's not active on the board anymore

Geemail:
jtsherri

(A-t)

(G-male)

(d0t)

(calm)

sorry, don't want him getting spammed

[MrGraphics]

I bought some cheap cork - about a 1/4" thick - the kind you make cork bulletin boards with. Traced the speaker, cut it with a razor blade, then cut 3/8" in to make the spacer. The cork makes a nice seal, and you can really tighten it down.

$2 solution.

[pzanity]

Cheers that's a good idea.

I may draw a design in autocad an have someone machine some PVC for it.

[taibanl]

Originally Posted by pzanity

Cheers that's a good idea.

I may draw a design in autocad an have someone machine some PVC for it.

Fair enough but I would just pay the price to ship a jtsherri spacer to the UK. its not that much.

[VP Electricity]

$2 but sounds pretty weak. Won't seal around the tab. You're not making a gasket, you're making a sizing ring which will seal out at the end of that tab-shaped hole. Need something stiff enough to seal that.

[tracer bullet]

Agreed. And something stiff enough to hold the woofer firmly in place if it's smaller than the hole you're trying to fill. Flex = loss of volume and loss of sound quality.

[pzanity]

I have some sheets of 7mm and 10mm foamex kinda like PVC.

But im a crazy guy with a jigsaw! Hah!

[MrGraphics]

That tab area . . . I broke the stock connector off the old speakers and then did some fab work. End result is I use the stock connector to wire in the speakers, and the problem with the tab is alleviated. Plus, unless you are sealing up the entire box, whatever TINY tiny amount of air that is leaking around the speaker (and trust me, there isn't any) is nothing compared to the 5 inch port on the side of the box.

[VP Electricity]

And how is the vent out of the primary chamber analogous to your leaking woofer mount?

This sounds like a really kludgy approach, but I'd love to see pictures to prove me wrong. And now you can't go back to stock...

[JimD]

I am not following this very well. I thought the idea on the underseat woofers was they were in a sealed enclosure. If you take a speaker intended for a sealed enclosure and put it in a vented enclosure it is not going to sound the same and may sound pretty bad. Not only do you need a rigid mount for the speaker, you need to seal that spacer ring to the car enclosure and then seal the speaker to the mount. Caulk should work. You could also use something like construction adhesive (for the spacer to the car). MDF (medium density fiberboard) is commonly used for speaker boxes and should make a good enough spacer ring. It is cheap. I hate the dust but it is not hard to work with. You can buy it at the home center and cut it with a jig saw or even a coping saw.

Jim

[VP Electricity]

Originally Posted by JimD

I am not following this very well. I thought the idea on the underseat woofers was they were in a sealed enclosure.

Jim

Uh, actually, I would not put it that way, and I haven't seen it out that way. I would say the point is you have 8" under your seat!

No one seems certain if the enclosure is sealed or vented with a tuned port or actually vented to the exterior and just acting as a truly infinite baffle.

If you mount a speaker in the enclosure and you connect an impedance meter to it and you look for a peak in the value of Z corresponding to a tuning freq of a tuned port, you don't find one. So I feel very comfortable saying its not a tuned enclosure.

The main chamber does vent to another chamber in the side rail. No one knows how big it is but do NOT seal up that vent.

As far as the rest of your post, all the underseat woofer replacements we sell have metal or HDPE rings that fit perfectly and foam gaskets... Skip the goop and the sawdust.

[JimD]

Thanks VP. I am used to home speaker design where the Qts, VAB, and F3 can be measured, the enclosure designed, and you pretty well know what will result. Cars seem odd to me because the mathmatical modeling of the enclosure seems to be essentially not possible in a lot of cases. This seems to be an example.

Do you pretty much always pick a good driver, put it in the enclosure, and equalize out anything you don't want in the frequency response? That is my impression of what is going on but I don't really know.

Jim

[VP Electricity]

Maybe you don't mean to sound condescending.

First off, whether you are in a room or a vehicle cabin, a speaker is only as good as TE room you put it in (with apologies to NpDang).

It is true that regardless of your projected enclosure/driver interaction and regardless of the fr that interaction should yield, when buried flush to the ground in the middle of a football field and tested, it will sound different in a car. It will sound different in a room too.

There are three woofers in production that bolt right into the BMW underseats and a handful more that can be made to fit with adapters. The woofer in this instance must also play midbass. Your T/S parameters will not tell you how the driver will respond in the 100-200 hz range - it will only tell you the theoretical roll off of the woofer/enclosure interaction. It's not like you have 200 woofers to choose among, and you need guidance through the maze.

If you are using a trunk sub and you are using the underseats as a band-passed midbass driver, the T/S parameters are close to useless for predicting underseat midbass performance. Most modeling software won't help you beyond a very early-stage point.

Our trunk woofer enclosures are specifically mated with woofers that "want" this size enclosure as its optimum - and then we use cabin gain and corner-loading of certain frequencies on top of that - but the enclosure is literally dead on, rather than depending on the cabin gain to get you to seem lower - we actually do play lower. The best performance is from a sub-bass/mid-bass 4-way system.

[nato-main-man-5am]

Originally Posted by taibanl

The most popular spacers are made by user JtSherri but he's not active on the board anymore

Geemail:
jtsherri

(A-t)

(G-male)

(d0t)

(calm)

sorry, don't want him getting spammed

Is he still in the business of selling these? Emailed a while back....

[taibanl]

Emailed him myself to check buy I am pretty sure, yes

[highcee]

Originally Posted by VP Electricity

There are three woofers in production that bolt right into the BMW underseats and a handful more that can be made to fit with adapters. The woofer in this instance must also play midbass. Your T/S parameters will not tell you how the driver will respond in the 100-200 hz range - it will only tell you the theoretical roll off of the woofer/enclosure interaction. It's not like you have 200 woofers to choose among, and you need guidance through the maze.

What are the three that will bolt right in?

[taibanl]

IIRC: SWS, Jehnert and Audio Systems

[highcee]

Thanks

[JimD]

VP,

Thanks for the explanation. Sorry if I sounded condescending, that was not my intent. I wanted to learn something and you were helpful.

Jim

[taibanl]

Originally Posted by Nathan_h

Is he still in the business of selling these? Emailed a while back....

Yup, JTSherri has 'em in stock...sure you spelled it right?

@gmail.com

[nato-main-man-5am]

Just connected with him tonite. Now to see if those Kicker's are still available at a good price, from the source I found last week!

Thanks.