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Author: Todd Marcucci
What Are They?
Why use it? These things are SMALL. If you want low end, and I mean CLEAR low end with low distortion and a lot of punch, you're typically looking at a high-dollar 10" or 12" woofer with some serious (and clean) power behind it. Due to the Shaker's high efficiency and low moving mass, you can accurately reproduce low frequencies with low power and quite frankly, crappy power. Even the top-of-the-line Shakers by Aura only handle about 50W RMS, and they are not the least bit picky about distortion in the source or amplification. They work just fine with cheap amplifiers, and don't need an amp with a high damping factor or excellent transient response.
These aren't a replacement for a sub. Well, they are, but you have to understand the theory. They don't work well with anything over about 70 or 80Hz. Vocals sound like hell through them, so they HAVE to be crossed over. The padding in the seat does a lot to help this, but I still recommend at least a 90Hz crossover or lower (I run mine at 60Hz). A sharp rolloff (12dB or more) helps as well. These will add the "punch" of a large woofer without the space requirements or the cost. I would still recommend some high-quality mid-bass driver with a 6" woofer. This will give you a little "boom" since the Shakers have mostly "punch."
A note of caution: these things are relatively low power. Depending on the model you get (see below), you might only need 20, 40, or 50W RMS. With the smallest ones, driving it with anything over 30W RMS probably not a good idea. The larger ones will handle much more- I'm using a 100W RMS amp without any boost on the low end. Generally, Aura rates their products conservatively for power handling. You can usually safely double their figures for RMS power, though they are still much lower power-handling than a sub of comparable output. Another plus for them, as they not only save space themselves but generally require a much smaller amp than most subs.
This install will specifically cover the "Pro Series" of Bass Shakers, mounted under the seat on a set of brackets. There are several other models out there that you can find if you look. Here are the Pros (right) next to a smaller, cheaper model from Parts Express (left):
For the curious, here's what the Pro looks like, opened:
You can also get some in the form of an "Interactor," a product that was marketed MANY years ago for the old 8-bit Nintendos. It was a "vest" that had one of these built into it:
They could be liberated from the vest and fit into a Prelude seatback nicely (see the NTPOG Bass Shaker Install page for more info. These will not fit easily into the S2000 seatback since it is so thin.
Suffice to say there are several different types available. Both Parts Express and MCM Electronics carried these at one point; they have both been out of stock for quite a while. If you search on the 'net you can find different dealers for both the "cheap" ones as well as the Pro Series.
What You Need
Removing the Seats
Before you can lift the seat up out of the car, you have to disconnect the seat belt warning switch:
Carefully lift the seat up out of the car- watch those seat rails, they are sharp and will scratch any plastic they contact. Set the seat aside somewhere safe.
This is where we ran the cabling for the Bass Shaker as well as for our amplifier power:
For our installation, the wire was threaded alongside the primary and then into the carpet (where it begins) and down to the hole in the carpet where the seat belt switch wiring is. The wire was covered in loom until it was sandwiched between the sheet metal and carpet/trim, from there on it is simply wrapped in electrical tape. The wire needs to be just long enough to reach the front of the seat bottom at it's forwardmost position (a little slack won't hurt).
Making Mounting Brackets
Very thick, wide steel would be ideal for this- something very rigid and strong. While this would be an ideal material to use, it's almost impossible to bend. Here, we went with a 1/8" x 1" wide aluminum flat stock. It's relatively easy to come by (your local hardware or home improvement store), somewhat easy to bend (much easier than steel) and can be drilled/tapped to accept bolts (if you decide to eliminate the nuts/washers for mounting).
After much experimentation (and many feet of aluminum), the brackets were finally bent to the following shape:
Four brackets were made, two for each shaker. The brackets are all identical, save for the mounting holes, shown below:
The brackets for each Shaker are mirror images of each other; the dimensions shown on the left side are the same for the right, taken from the right-hand edge of the right side bracket. It is not dimensioned, but the shaker is to be positioned in about the center of the flat portion of the brackets. It is a good idea to test fit the brackets first, then mark and drill holes for the Shaker once they are mounted to the seat. The brackets utilize the two "square" holes in the middle of the seat bottom, and require two new holes to be drilled at the front lip of the seat.
For this installation, the aluminum bar was drilled and tapped to accept the 8-32 screws that will be used to hold the Shaker to the bracket. This is not necessary, but greatly simplifies the mounting (you don't have to fiddle with the nuts on the other side of the bracket). Note that to do this, you need a #18 drill bit (for a #8 screw tap) and NOT the 3/16" bit we called out earlier (which is for a through- hole). We assume that if you are going to drill and tap your own bracket, you already know what you are doing.
Once you have all 4 drilled, they should look something like this:
Attach all four bolts like this, or with 4 locking washers and nuts (or locking nuts):
Now you can mount this mess to the seat. Flip the seat upside down (preferably resting on something solid), and you will see a series of metal "brads:"
Each of these (circled) needs to be removed to get behind the seat fabric and cushion. Don't worry, we'll be putting it back together with the zip ties (just as strong). You might not be able to see it at first, but each "circle" is a single piece of wire wrapped in a circle. If you grab one end with a pair of needlenose, you can "open" them and remove them:
Once you remove all of these, you will need to remove the bolt on the inside edge of the side of the seat:
This will allow you to peel the fabric back off of the seat bottom and expose it. The next step is to drill mounting holes for the bracket in the seat. You will notice that there are already two square holes in the seat bottom, which the brackets are designed to use:
The first two bolts can be test-fitted, then the next two at the front lip of the seat marked and drilled. Once you are certain of the location, drill the two holes through with the 1/4" drill bit. Install the hardware for these screws and you are ready to button up the seat.
Using the zip ties mentioned above, zip tie the seat fabric back into place where the metal brads were before:
Don't forget the bolt on the side of the seat, then re-install the seat with the four bolts that were removed. Hook up the bass shaker to the amp... and you're done!
As always, feel free to email the author with comments, critiques, etc.
This page last updated 12/21/01.
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