Automotive subwoofers produced by the industry are not particularly aesthetically pleasing. A large square box not only spoils the appearance, but also takes up a lot of space in the trunk, reducing usable volume. What if the refined ear of a music lover requires a full range of sound frequencies of a musical composition, and practicality does not allow sacrificing trunk space? Making a subwoofer “Ste alth” with your own hands will help correct the situation.
What is a subwoofer for?
Some car enthusiasts ask themselves the question: do you need a subwoofer in your car? They believe that the full sound of music can be obtained from full-sized speakers with a diameter of 16.5 cm. Indeed, audio equipment manufacturers write that speakers of this size can reproduce frequencies with a lower threshold of 20 Hz. This is the minimum frequency that the human ear can hear.
Howeverif you delve into this issue in more detail, it turns out that the volume at this frequency is much lower than at a frequency of, say, 1000 Hz. In this case, the sound of such instruments as double bass, bass guitar, percussion instruments will suffer. Anything that sets the rhythmic pattern of a musical composition will have a weak sound.
This is where the subwoofer comes in.
The very name of it suggests that it is a subwoofer. They are divided depending on the size into 3 categories: 25 cm, 30 cm, 38 cm. The larger the diameter, the higher its volume and the more acoustic pressure it creates.
Why Ste alth?
Car subs come in open and closed types. Open ones are installed in the rear shelves or mounted on the back seat, which is not a good option, as the passenger will feel the full power of musical vibrations.
Closed subs are made in a wooden or plastic case and are installed in the same trunk. Well, subwoofers like “Ste alth” will help to solve the problem of aesthetics and rational use of space.
The name "Ste alth" belongs to the American fighter-bomber F - 117. It is the first aircraft to embody ste alth technology for ground-based radars. As for the Ste alth subwoofers, they are made in such a way as to be invisible in the trunk of a car. When inspecting the open trunk, they are not striking. Also a kind of invisibility.
How to calculate subwoofer volume
Making a subwoofer "Ste alth" with your own hands is the creation of a box for a large speaker, which pumps air by making oscillatory movements. In order for it to function normally, it needs a certain volume inside the case in which it is installed. For each size, there are recommendations for choosing the volume of the box.
| Speaker size in cm | 25 | 30 | 38 | 46 |
| Volume in liters | 15-23 | 24-37 | 38-57 | 58-80 |
These volumes cannot be neglected. Otherwise, the sound will be flat, and the life of the subwoofer will be significantly reduced due to excessive air resistance to the operation of the speaker membrane.
As a rule, the subwoofer is installed in a niche formed by the rear wheel arch and the rear fender of the car. Therefore, there are not so many options for choosing the size of the speaker. Before you make a box for the Ste alth subwoofer, you need to calculate the volume of this niche in order to get an idea of \u200b\u200bthe size of the speaker. It must match the recommended for this volume or be a smaller diameter.
Depending on the shape of the niche, the calculation of the volume will be different. Since the shape is complex, formulas are suitable for calculating figures such as a parallelepiped, a triangular prism. It is possible that the niche space will have to be conditionally divided into several simple geometric shapes, and the volume calculated as their total sum.
How does a subwoofer fit into the interior of a car?
As mentioned above, the sub should be invisible in the trunk of a car. To achieve this, the Subwoofer Ste alth Enclosure must meet the following requirements:
- Its shape should be thought out in such a way as not to “eat up” the useful volume of the trunk.
- The appearance and texture of the surface should be similar to the factory coating of the luggage compartment. For these purposes, a carpet of different colors is used.
- The subwoofer must not interfere with the removal of the spare wheel and vehicle tools.
Never place a Ste alth in the spare wheel well. Although its volume may be suitable for this purpose, it is easy to damage an expensive speaker in this case.
Required materials for crafting
To make a Ste alth subwoofer with your own hands, you will need tools, materials, and most importantly free time. Since the shape of the Ste alth is curvilinear, the body will be made of fiberglass using epoxy resin. The gluing process itself takes several days, because before each new layer is applied, the previous one must be cured.
For work you will need:
- Fiberglass T 13. This is a non-combustible structural material of high strength. It is able to withstand aggressive environments and is used to create high-strength fiberglass. Actively used in car and boat tuning.
- Epoxy glue. The price for it depends on the volume of packaging and the manufacturer. Since the volumethere is a lot of work to be done, then work will require from 1 to 3 kg.
- Plywood or MDF. This material will be required to make the outer part of the case into which the speaker will be embedded. The thickness should be from 0.8 cm and above. The thicker the better.
- Making tape 50mmx50m, one or two rolls.
- Carpet. This material will allow you to make the body in the same style as the trunk.
- Glue “Liquid nails” for gluing carpet.
- Primer for wood. In order for the plywood to not absorb moisture and not delaminate, it will need to be processed.
- Wood putty. This material will eliminate surface irregularities before pasting with carpet.
In addition, you will need a router or a jigsaw to cut out the landing rings for the speaker.
Shaping the body
The production of the “Ste alth” subwoofer begins with pasting a niche. A body will be created inside it. To do this, masking tape 50mmx50m is cut into strips that are glued to the plastic sheathing or carpet inside the niche. The resulting paper layer will serve as the basis for applying the first layer of fiberglass.
Fiberglass T 13 is available in rolls with a width of 90 to 100 cm. This width is enough to completely cover the niche in both width and height.
Before the formation of the first layer, it is necessary to isolate the paper base from contact with the epoxy. To do this, paper can be coated with paraffin, stearin, parquet polish.
Then you need to stir the epoxy withhardener in accordance with the instructions and apply it to the paper matrix. After the first layer has hardened, it is necessary to apply another one, on which the fiberglass will be laid.
A flap of fiberglass is taken with a small margin, which, after the formation of the body, will need to be cut off. After applying the first layer, the fiberglass is rolled with a roller and a coarse brush. It is important that the material is completely impregnated with epoxy adhesive. The price of poor-quality work is the delamination of the body after polymerization.
Then the procedure is repeated. Fiberglass thickness 0.3 mm. To give the necessary strength, you need to lay out from three to five layers. To make it more convenient to work, after the first layer has hardened, the case can be removed from the trunk and work can be continued by gluing fiberglass from the outside, and not from the inside. The process is not fast. It will take several days to make a Ste alth subwoofer with your own hands.
Depending on the air temperature and the amount of hardener, the epoxy resin takes from 30 minutes to several hours to dry. The hardener must not be abused. Firstly, the case will turn out to be fragile, and secondly, you may not have time to apply fiberglass before the resin hardens.
Making the outer cover
The lid is cut with a jigsaw according to the size of the outer side of the resulting body. The inner hole is made slightly smaller than the diameter of the speaker. Then two rings are made, the inner diameter of which must match the diameter of the hole for the speaker. These rings should be the catwalk.
After the lid is made, it needs to be aligned. For this, a polyester putty is taken and applied to the surface in a thin layer with a spatula. After it dries, it needs to be sanded with sandpaper. If irregularities remain, then repeat the procedure.
Then, using a primer, you need to protect the surface of plywood or MDF from moisture. After the primer dries, the mounting rings for the speaker are glued to the surface of the cover. To do this, use wood glue or the same epoxy.
Carpet pasting
In order to stick the carpet on the outer cover of the “Ste alth”, you need to cut off a piece of fabric, the dimensions of which will exceed the size of the subwoofer cover by 10 cm. This margin is needed in order to hide the edges of the carpet on the reverse side.
A good result is obtained by using Liquid Nails, and the best option would be to use 888 Ultra Spray Adhesive. The spray allows you to apply the adhesive base evenly.
Glue is sprayed on plywood and carpet. Then an interval of 60 seconds is maintained, after which the fabric is laid on plywood and straightened from the center to the edges so that no wrinkles remain. Each section of the carpet must be carefully pressed to the surface for better fixation. Bonding occurs instantly and depends on the magnitude of the pressure. Complete solidification occurs in a day.
Final installation
The final step in making the Ste alth subwoofer with your own hands is installing the speaker. To do this, in the back of the boxa hole is drilled for the wire. The speaker is screwed to the podium using self-tapping screws and closed with a decorative grille on top.
After that, the whole structure is inserted into the niche between the wing and the rear wheel arch and fixed with self-tapping screws.
The last thing to do is connect the sub to the amplifier and enjoy the music.
