home > Computer > Calculate the volume of the subwoofer box using a calculator. Programs for calculating: subwoofers, bass reflex, inductance, and others

Calculate the volume of the subwoofer box using a calculator. Programs for calculating: subwoofers, bass reflex, inductance, and others

There are many programs useful for designing and creating car acoustics. Most of it relates to the calculation of low-frequency loudspeakers (subwoofers), because the rest, today, cannot be calculated.
Armadillos subwoofer software- LEAP/LMS from Linear X and TermPro from Wayne Harris' company of the same name cost a lot of money.
Other commercial products cost some money, but also a lot (well, 100 - 150 dollars per package). This is quite suitable for professional installation companies, but a bit much for an amateur who may be planning to calculate a single subwoofer. Fortunately, there is both shareware and completely free things. They differ in interface and ease of use, but, in essence, are based on the same Till-Small model, so the results will be similar.
The programs that I found most suitable based on personal experience of use are placed in this library. I supplied them brief description to make it easier to navigate.
In practice, there is also a need to calculate passive crossovers and their inductances. The two programs given are by far the best in this genre.

Blaubox subwoofer calculation program

Eat after reading!

BLAUBOX is a creation of Blaupunkt, as the name implies, the program is completely and absolutely free. The somewhat simplified and rough graphics are fully compensated by the fact that the program works, firstly, quickly, secondly, it can calculate all three main types of subwoofers (closed box, bass reflex, bandpass subwoofer), thirdly, it is extremely easy to use, - fourth - can draw working drawings of the box based on the calculation results.

Program for calculating subwoofers Perfect Box 4.5

Eat after reading!

Perfect Box 4.4 is a pre-sale version of the program, but it is almost completely equipped with functions and options. Outwardly it is a rough DOS thing. In fact, it is the best program, in my opinion, if you get the hang of it. Calculates closed boxes and bass reflexes. As a dowry, there is a fairly large database of speakers, which you can easily update as the need arises, as well as something of little use, but fun - the EQ2.EXE program, with which you can calculate the active frequency response correction link. The program is tied to the basic parameters of the frequency and quality factor of the correction filter.

Program for calculating subwoofers Box Plot 2

Eat after reading!

Boxplot 2 is a pre-sale version of the program, and therefore some of the functions do not work. The main advantage is that the program is very instructive, since right on the screen you can vary the parameters H = fb/fs (the ratio of the bass reflex tuning frequency to the resonant frequency of the head and ALPHA = Vas/Vb (the ratio of the equivalent volume of the head to the volume of the box, including a closed one). After five minutes of working with the program, a person who has never read anything on loudspeaker theory in his life already knows the most important dependencies. For practical calculations, the program is not very convenient due to its reduced functions, although with some skill it is possible to work. However, if anyone wants to pay 25 dollars - it says somewhere - where...

Program for calculating subwoofers WinSpeakerz

Eat after reading!

WinSpeakerz - spelling as in the original - the work of a certain John Murphy, TrueAudio company. The program is quite commercial, costs about $130, and a demo version is provided for free, without a database of speakers and other amenities (including a 150-page manual). The program is really good because, among other things, it has a special function for taking into account interior acoustics.
Among the active professional users is the BLUZMOBILE studio, where they are very pleased with the program.

Program for calculating subwoofers JBL Speakershop

Eat after reading!

JBL branded products. They say it sells and is worth the money. The copy posted here was found on one Ukrainian server, please address all questions regarding copyrights and other things to the friendly Ukrainian people. I have no idea how this program got onto my server... ZIP archive monstrous size. After unzipping and installation it gives two modules: for calculating subwoofer enclosures and for calculating passive crossovers.

Program for calculating interference distortions of the frequency response by G. Tatevyan Harmon3way

Eat after reading!

Program for Microsoft Excel, ready to go

Program for calculating the equivalent volume of the head using the added mass method, proprietary work of VASCalc

Eat after reading!

Without miracles and bows, a working tool.

Generator of audio frequencies (and special form signals), working with all different sound cards, definitely NCH Gen

Eat after reading!

NCH Tone Generator is an easy-to-use program that generates (if there is presence sound card) signals of a sinusoidal shape (with a harmonic coefficient of about 0.01%), rectangular (with quite decent fronts). Sawtooth, etc. There is also a signal with a white noise spectrum, however, there are some complaints about it. The program is 200 kilobytes, nothing at all. You need to download it somewhere and run it, the rest happens by itself.

Calculation program for a Power Port type bass reflex (recipe and patent from Polk Audio) Power Port

Eat after reading!

This is what Matt Polk came up with. Or George Klopfer. The idea is to reduce the speed at the output of the bass reflex tunnel and at the same time reduce its length while maintaining the same setting. The calculation program is designed as Excel file, I once dragged it into my native language. To prevent this whole thing from opening in a browser, it is archived in ZIP. George Klopfer is an expert in Russian literature, so I bet he won't be offended that some of his works have been translated into Russian. I'll ask in Las Vegas in January, just in case. In the meantime, use it and tell us what happens.

Passive crossover calculation program P.X.O.

Eat after reading!

The PXO (Passive X-Overs) program, as befits its age, runs under DOS and works perfectly. You select the frequency (or frequencies, for a three-band system) of the section, the slope slope from 6 to 24 dB/oct and the filter type (Butterworth, Linkwitz-Riley, etc.), and in return you receive graphs of all the main characteristics and values of the elements included in the filter chain, the latter being schematically depicted in the lower window of the user interface. Note:
When everything is done to your taste, the question naturally arises: “How to calculate inductance?” - they are not ready-made, unlike capacitors. For this purpose it serves even more simple program, shown in the table of contents on the left - COILS.EXE

When making a homemade cabinet subwoofer for a car, the question always arises: how to calculate the cabinet for the subwoofer? First, if the volume is unknown, you need to calculate the volume of the box for the subwoofer and then, already knowing it, calculate the box for the subwoofer.

Order the manufacture of the case!

Case size calculation

When the volume of the body is known, the shape of this body does not affect the sound.
There are various programs for calculating a box for a subwoofer (a program for calculating a subwoofer box is “JBL SpeakerShop” or “Winisd beta.”), but you can simply do the calculation, knowing yourself that the volume is V=h x L x A(where h is height, L is length, A is width).

For example, how to calculate a box for a subwoofer, if for a 12-inch subwoofer (305 mm), the recommended volume is 45 liters. The measured permissible height for the body in a car is 340 mm (h=340 mm), length 680 mm (L=680 mm), let's calculate the width. A=V/Lxh

The permissible height (h) for space in the car is h=340 mm=34 cm=0.34 m, and the permissible length L=680 mm=68 cm=0.68 m. 1 liter = 1 10−3 m³ 1 l = 0.001 m³ then V = 45 l = 0.045 m³.

Don't forget that there is an internal and external volume, so you need to take into account the thickness of the material from which the subwoofer box is made.
If the box is made of MDF with a thickness of 2 mm (0.02 m), then we reduce the measured values of height and length by the thickness of the MDF on both sides and calculate the internal volume. h = 0.34m -0.02 x 2= 0.3m; L = 0.68m – 0.04m = 0.64m.

In addition, it is necessary to take into account when calculating the volume of internal struts used in the manufacture of the body. Suppose we use a beam with a thickness of 3 cm by 3 cm as spacers, then we get 4 bars with a length of 0.64 m (length L = 0.64 m) and 4 bars with a length of 0.24 m (the length obtained from the height “h” reduced by 3 cm on both sides 0.3 – 0.03 x 2 = 0.24). For now we will not take into account the internal struts on the sides. The volume that the spacers will have in this case is V=(0.03 x 0.03 x 0.64) x 4 +(0.03 x 0.03 x0.24) x4=0.003168 m³. Then we increase the volume of the box by the volume of the spacers. V= 0.048168 m³ A = V/L x h = 0.048168 m³ / 0.3 m x 0.64 = 0.2509 m.
If the volume is increased by the volume of the side struts, then A = 0.255 m.
We want to make a subwoofer enclosure with a slightly inclined front wall, in this case the lengths of the side walls will change: if A = 0.255 m, then A = a + b / 2 = 0.33 + 0.18 /2 = 0.255, that is, reduce the value length “b” by the amount by which you increase the value “a”.

for example, the subwoofer housing is installed in the wing niche, and will have a complex geometric shape, repeating the geometry of the niche, while rear end the subwoofer housing has different shapes. In this case, you will have to calculate the subwoofer housing in parts, counting separately the volumes of “1” and “2” parts.

Making a box for a subwoofer with your own hands: step-by-step instructions

12-inch speaker for subwoofer Before you start designing and assembling the box, you need to decide on the choice of speaker. We recommend choosing 10-12 inch imported speakers, as they are most often used in car subwoofers and are best suited. We described in detail how to choose a speaker for a subwoofer in a previous article. The box design also has important: the sound quality and volume depend on it low frequencies.

What types of subwoofer boxes are there?

There are several types of subwoofer boxes. The sound quality you get at the output directly depends on the design of the box. Below are the most popular types of subwoofers:

Closed box- the easiest to manufacture and design, its name speaks for itself. The woofer is placed in a sealed wooden case, which improves its acoustic characteristics. Making a subwoofer in a car with such a housing is quite simple, but it has the lowest efficiency.
Bandpass 4th order is a type of subwoofer whose body is divided into chambers. The volumes of these chambers are different; in one of them there is a speaker, and in the second there is a bass reflex (air duct). One of the features of this type of subwoofer is the design's ability to limit the frequencies that the cone reproduces.
Bandpass 6th order differs from the 4th order by the presence of another bass reflex and another camera. There are two types of 6th order bandpasses - the first has one bass reflex, and the second has two (one of them is common to both cameras). This type of box is the most difficult to design, but produces maximum efficiency.
Bass reflex– a subwoofer with a special tube in the housing. It vents air and provides additional sound from the rear of the speaker. In terms of complexity in manufacturing and sound quality, this type is a cross between a closed box and a bandpass.

Wanting to get the most high quality sound, you can opt for bandpasses. But this type of design has many details that must be carefully designed and calculated. All this can be done using special program WinlSD, which will not only determine the optimal size and volume of the subwoofer, but also create a 3D model of it, and also calculate the dimensions of all parts.

Unfortunately, this program requires at least minimal knowledge in this area and the average car enthusiast is unlikely to be able to do everything right the first time. Moreover, in order for the program to work correctly, it needs some speaker parameters, which are also not known to everyone. If you do not plan to take part in car audio competitions, we advise you to discard the bandpasses.

The bass reflex will be the most optimal solution for a homemade subwoofer. This type of box is good because the tube (bass reflex) allows you to better reproduce the lowest frequencies. In fact, this is an additional sound source that contributes to the sound of the subwoofer and increases efficiency.

What materials do we need to assemble the subwoofer?

Multilayer plywood for the subwoofer box The material for making the subwoofer box must be strong, dense and well insulating sound. Multilayer plywood or chipboard is perfect for this. The main advantages of these materials are their affordable price and ease of processing. They are quite durable and provide good sound insulation. We will make a subwoofer from 30 mm thick multilayer plywood.

To make a subwoofer box we will need:

Wood screws (approximately 50-55 mm, 100 pieces)
Soundproofing material (Shumka)
Drill and screwdriver (or screwdriver)
Jigsaw
Liquid Nails
Sealant
PVA glue
Carpet, approximately 3 meters
Klemnik

Subwoofer box drawings

In this article we will make a box for a subwoofer with a 12-inch speaker. The recommended box volume for one 10-12 inch speaker is 40-50 liters. Calculating a box for a subwoofer is not difficult, here is an approximate diagram with the dimensions of the panels.
Scheme and drawing of the box
It is worth paying attention to the minimum distance from the walls of the case to the speaker. It, like the volume of the entire box, is calculated based on the inner surface.

Assembling a subwoofer box with your own hands

You can start assembling. We use a 12-inch Lanzar VW-124 speaker.
12 inch speaker for subwoofer
Its diameter is 30 cm, and the first thing you need to do is cut a hole for the speaker. The minimum distance from the center of the diffuser to the subwoofer wall is 20 cm. We measured 23 cm (20 cm + 3 cm plywood width) from the edge of the panel and cut a hole with a jigsaw. Next, we cut a hole for the bass reflex slot; in our example, it has a size of 35*5 cm.

Cut out the bass reflex slot and the hole for the speaker

Instead of a slot, you can use a classic air duct - a tube. Now we assemble the bass reflex slot and attach it to the front panel of the subwoofer. We go along the joints with liquid nails and tighten them with self-tapping screws.
Assembling the bass reflex slot panels
It is important to tighten the screws very tightly so as not to leave any voids. They will create resonant vibrations that will ruin the sound of the subwoofer.

Next, we assemble the side walls of the box, having previously lubricated them with liquid nails, and tighten them tightly with self-tapping screws.
Side walls of the box
On back cover box you need to cut a small hole for the terminal block. We connect all parts of the body. We make sure that we cut and fastened all the parts correctly.
Assembly box
We insert the speaker. Let's look and admire.

Interior decoration

Let's move on to the interior decoration of the box. The first thing you need to do is seal all the joints and cracks with epoxy glue or sealant. Next, using PVA glue, we glue soundproofing material onto the entire inner surface of the box.
Cover the body with Shumka
Cover the body with Shumka
Now we cover the entire outer plane of the box with carpet, including the bass reflex slot. You can attach it with epoxy glue or using a furniture stapler.
The box is covered with carpet
Next, insert and screw the speaker tightly. The subwoofer is almost ready, all that remains is to stretch the wires from the speaker to the terminal block and connect the amplifier.
Installed subwoofer with amplifier
We bought an additional amplifier, but you can also make it yourself. This is quite difficult, as it requires knowledge and practice in the field of radio engineering. You can also use ready-made kits and circuits for radio amateurs, like Master-KIT, and assemble the amplifier yourself. The only requirement for the amplifier is that its maximum power must be less than the maximum power of the speaker.

Making a stealth subwoofer with your own hands

DIY stealth subwoofer Tired of carrying a huge box in the trunk? Then the stealth subwoofer is just made for you. This unique type of case is more practical than the classic box. It doesn't sit in a square box in the middle of the trunk and takes up less space. Often, stealth is installed in the inner part of the wing, sometimes in a niche instead of a spare wheel. The minimum volume of the box that requires a 10-12 inch speaker for normal operation is 18 liters.

To make a passive stealth subwoofer we will need:

subwoofer;
protective grille and socket for connection to the amplifier;
wire for connecting the speaker to the outlet;
multilayer plywood or chipboard (thickness 20 mm);
a small piece of fiberboard;
epoxy adhesive;
brush;
fiberglass;
mounting tape;
polyethylene film;
wood screws;
drill, jigsaw.

Choosing a location to install the housing

After choosing the place where the stealth will be installed, we empty the trunk and begin manufacturing the body. You can remove the trunk trim where the subwoofer will be installed to place it even closer to the fender. First of all, lay a plastic film on the floor of the trunk. It performs two functions at once: it protects the trunk lining from epoxy glue and allows us to make a mount to which we will screw the bottom of the subwoofer. Next, we cover the inside of the wing with mounting tape in two layers.
Cover the trunk with masking tape
We cut the fiberglass into small pieces, approximately 20x20 cm. We place pieces of fiberglass onto masking tape and glue them with epoxy glue. It is better to overlap the fiberglass fabric so that there are no obvious joints and seams.
Epoxy glue + glass mat
We sculpt layers of fiberglass on top of each other, simultaneously lubricating them with epoxy glue, until the thickness of the sheet reaches 10 mm (about 4-5 layers).
Panel thickness approximately 1 cm
The material will harden in approximately 12 hours. To speed up the process, you can use a lamp. Now we cut out the bottom of the subwoofer and glue it to our body. The joint is treated with sealant or glued with epoxy resin.
Glue the bottom
In this particular case, the shape needs to be adjusted to the trunk hinges so that our homemade subwoofer did not prevent him from closing. After we have cut off all the excess, we cut out the side walls from chipboard and top cover. We make the rounded part from plywood, we did it “by eye”.

Making the side, top and bottom walls of the box

To make it easier to give the plywood a rounded shape, you must first wet it, give it the desired shape, secure it and let it dry.

Chipboard sheets must be glued with epoxy glue or sealant, and then fastened with self-tapping screws. We also glue the fiberglass box using epoxy resin, and when it dries, we fasten it with self-tapping screws.
Glue and fasten the parts
For better sealing, you can glue the seams again. We applied another layer of epoxy glue and pressed the structure with sand to help the glue adhere better.
Sandbags for better traction
Next we can measure the front panel and cut it out. Using a jigsaw, cut out a circle for the speaker. In order to securely attach the front panel to the body, you need to tighten it with self-tapping screws on all sides. That is, you need to install bars on the entire inside of the panel, at a distance slightly greater than the thickness of the plywood (in our case, we attached the bars at a distance of approximately 25 mm from the edge of the panel). Thanks to this, we will be able to secure the front part at the top, bottom, sides, and most importantly, securely attach it to the rounded element.
Preparing the front panel
Cut a hole in the end for the socket.
Cutting a hole for the terminal block
In the end, it was decided to add two more layers of fiberglass and epoxy glue to the curved part of the body for the stealth subwoofer.

We carry out final assembly: install the socket and connect the speaker to it, but do not screw it in yet. Then there are two options - paint the subwoofer, or cover it with carpet. Painting is a little more difficult, since you must first level the surface. For this we used universal putty.

The proposed method for calculating a bass reflex is based on the simplest measurements carried out with a very specific instance of a loudspeaker installed in an acoustic bass reflex and on a nomographic determination of the dimensions of the latter.

First of all, guided by Fig. 1 and the table, it is necessary to make a “standard volume” - a sealed plywood box, all joints of which are carefully adjusted, glued and coated with plasticine to avoid air leaks.

Compact speakers for high-quality sound reproduction

Closed box calculation (Version 2)

Acoustic design in the form of a closed box can be considered as an extreme case of a bass reflex box with an infinitesimal opening. Equivalent acoustic circuit a low-frequency head in a closed box can be obtained if in the circuit of Fig. 3 discard the elements related to the inverter. The corresponding frequency response of the loudspeaker coincides with equation (17) with y3 = y4 = 0.

Among the many types of frequency responses that can be obtained for a closed box loudspeaker. Of greatest interest are the smooth second-order Butterworth frequency responses. These characteristics are formed under the condition that the relationships between the parameters of the head and the box, expressed by equation (27) with f b / f s = 0, are satisfied. A feature of loudspeakers with frequency characteristics Butterworth of the second order is the fact that the cutoff frequency f 3 (29) coincides with the resonant frequency of the head in the box f c .

Bass reflex calculation

Due to frequent letters asking for help in calculating this or that acoustic design, I am writing this article. I won’t calculate the design for anyone, I don’t always have time. I created this site specifically for those who are interested in acoustics and want to understand it. I’d rather lay out ready-made options and examples of calculations for the lazy, and then figure it out yourself, use your brain. So.

In the low frequency range, the performance of the loudspeaker does not depend on the shape of the box or the type of bass reflex, but is determined only by two parameters of acoustic design - the volume of the bass reflex box V and frequency of its adjustment Fb. The calculation of acoustic design basically comes down to finding these quantities.

FAQ on speakers and subwoofers

In connection with multiple questions about how to calculate housings for speakers, I am posting several articles related to the calculation of acoustic design for speakers. Don't forget that acoustic design is important for LF heads. And so we begin....

Lately we have been hearing a lot of questions about speakers and subwoofers. The vast majority of answers can be found in the first three pages of any book written by professionals. The material is addressed primarily to beginners, lazy ;) and rural home-made workers, prepared on the basis of books by I.A. Aldoshchina, V.K. Ioffe, partly Ephrussi, magazine publications in Wireless World, AM and (a little) personal experience. Information from the Internet and FIDonet was NOT used. The material in no way pretends to cover the problem completely, but is an attempt to explain the basics of acoustics at a glance.

Most often the question sounds something like this: “I found a speaker, what should I do with it?”, or “Comrade, they say there are such subwoofers...”. Here we will consider only one option for solving this problem: Using the existing speaker, make a box with optimal low-frequency parameters, as far as possible. This option is very different from the task of the factory designer - to tighten the lower frequency of the system to the value required according to the specifications

Sound at the end of the tunnel

“Volodya, when you’re in the warehouse, grab the ports for the phasics...”
(overheard in one of the Moscow installation studios)

When AutoZvuk was still small and sat under the wing Salon AB, the first two parts of the trilogy about subwoofers have been published - about what to expect from different types acoustic design and how to choose a speaker for a closed box.

A significant portion of those who, contemplating life, decided to treat the bass armament of their car with understanding, could, in principle, get by with this. But not all. Because there is at least one more, extremely popular type of acoustic design, which is not inferior in popularity to a closed box.

Bass reflex in Russian literature, bass reflex, ported box, vented box in English - all this is, in fact, a sound engineering implementation of the Helmholtz resonator idea. The idea is simple - a closed volume is connected to the surrounding space using an opening containing a certain mass of air. It is precisely the existence of this mass - that same column of air that, according to Ostap Bender, puts pressure on any worker, and produces miracles when a Helmholtz resonator is hired to work as part of a subwoofer. Here, a sophisticated thing named after a German physicist takes on the prosaic name of a tunnel (in bourgeois port or vent).

Charging....

Then he began to calculate the volume of the violin box, and this work was long and exciting. …. The volume cannot be reduced - the violin will wheeze and begin to drone dully. If you increase it, it will squeal piercingly, the bass will become dull and weak.…
(A.A. Weiner, G.A. Weiner Visit to the Minotaur)

The article found out why they are good Various types acoustic design and why they are bad. It would seem that now “the goals are clear, let’s get to work, comrades..” But that was not the case. Firstly, the acoustic design, in which the speaker itself is not installed - just a box assembled with varying degrees of care. And often it is impossible to assemble it until it is determined which speaker will be installed in it. Secondly, and this is the main fun in designing and manufacturing car subwoofers - the characteristics of a subwoofer are worth little outside the context of the characteristics, at least the most basic ones, of the car where it will work. There is also a third thing. Mobile acoustic system, equally adapted to any music - an ideal rarely achieved. A competent installer can usually be recognized by the fact that, when “taking readings” from a client ordering an audio installation, he asks to bring samples of what the client will listen to on the system he ordered after its completion.

As you can see, there are a lot of factors influencing the decision and there is no way to reduce everything to simple and unambiguous recipes, which turns the creation of mobile audio installations into an activity very much akin to art. But it is still possible to outline some general guidelines.

Previous

In this article I want to tell and show how you cancalculate subwooferand what you need to pay attention to when designing in the following programs:WinISD 0.44, WinISD 0.50a7. Detailed description programs .

The box will be calculated for a ten-inch speaker Audiobahn 1051T. Let's begin! Launch the program WinISD 0.50a7

1. Create a new project (New Project).
2. By clicking this button, select a speaker from the program database.
3. View T/S parameters.

5. Select the number of speakers.
6. Installation type.

Normal - all speakers are on one panel.

Isobaric speakers stand face to face.

7. Speaker efficiency. Shows which type of case is most suitable.
8. Selecting the type of box.

Closed box - the name speaks for itself

Bass reflex - a box equipped with a pipe (bass reflex).

Band pass 4th order - the speaker is located between two cameras, one of them has a bass reflex.

Band pass 6th order - located between two cameras, both equipped with bass reflexes.

Passive radiator - in one closed box there is a speaker and a passive radiator (speaker without magnet)

We choose which type suits us and click next (Next)

Next, the program offers a way to design the frequency response in various ways. I don’t focus on this point and click next.
If you select Passive emitter, the program will prompt you to enter the following T/C parameters of the passive emitter:

Vas is the enclosed volume of air excited by the speaker.
Fs - resonant frequency.
Xmax - maximum diffuser stroke.
QMS – Mechanical quality factor.
SD is the diffuser area.

Driver tab.

9-10. Again, you can specify the number and type of speaker installation.
11. Additional features.
Box tab.

12-13. Drawer chambers
14. Chamber volume.
15. Camera setting frequency.

Vents tab

16. Number of bass reflex(s)
17. Diameter of Bass Reflex(s)
18. Length of the Bass Reflex(s)
19. Round or rectangular type. You can change the nav to a circle.
20. Type of bass reflex.

Let's move on to the main calculation of the box:

21. Click on the schematically shown box with the right mouse button while holding it, move the cursor along the (X) axis horizontally, change the volume along the (Y) axis vertically to change the frequency. Similar to the Left mouse button to change the parameters of the lower camera. The crown of the curve should be above the red line between 35Hz and 120Hz if this is a subwoofer as wide and flat as possible.

Transfer function magnitude. frequency response

Something like this, but the lower limit is 40Hz and the upper limit is 113Hz, this is also suitable.
Where I marked with red lines, in practice the frequency will be cut off by a crossover.

Select the chart: Maximum Power.

In this graph, the program shows the maximum power versus frequency. It can be seen that there is a decrease in power, a peak decrease of 60 watts at 39 hertz; in practice, the speaker cone does not have enough travel (Xmax) and unpleasant sounds appear - distortion. On the finished product, this must also be taken into account and the power limited.

Select the Maximum SPL chart

Maximum SPL. This graph shows the maximum sound pressure

The decline is also visible. For the same reason. The last two graphs are from another speaker, I showed them to make it clearer.
Here are the graphs for our test subject. The first one is a little implausible: from 0 Hz to 25 Hz all speakers have a roll-off.

Now you need to decide on the size of the box in which the speaker will be installed.
To do this, launch the WinISD 0.44 program and click new project.

We need to enter the parameters of our speaker into this program because... it is not in its database; to do this, click “New”
Let's move on to WinISD 0.50a7

22. By clicking this button you can see the T/S parameters that need to be entered into WinISD 0.44.

Enter the parameters, click OK and close this window so that it does not interfere.
Let's create a new project.

23. Rearrange the checkbox to select the speaker.
Click next and do exactly the same as in WinISD 0.50a7

We transfer the mailbox parameters from WinISD 0.50a7 to WinISD 0.44.

24. Click to start calculating the size of the box.
25. Click and the program displays the optimal size in its opinion.
We have at our disposal a 10 inch speaker with a total outer diameter of 300 mm to fit it into the box dimensions W and D should not be less than 300 mm
26. Enter width 300mm equals 0.300 METER
30. You can change the units of measurement by simply clicking on the dimension, in this case the letter “m”
28. Enter length 0.300 meters
27. Click on “H” and the program shows the height.
31. Pay attention to L1 and L2; this is the height of the cameras; you need to look so that the insertion depth of the speaker does not exceed the value of L2.
But we need to take into account the thickness of the material; it will overlap; in the nutria there is a shelf in which the speaker is located, and its thickness must also be taken into account for the speaker itself; it also occupies it; I’ve already taken it into account; if the box is large, there should be spacers inside, they must also be taken into account. It turns out that there are 7 parts, in order to calculate the parts correctly it is necessary to take into account that some of them will overlap because the program shows internal diameters. With the letter “P” I will indicate the thickness of the material, which must be added to other values.
1)D x W
2)D x W
3)D x W
4)H+(P*3) x D
5) H+(P*3) x D
6) H+(P*3) x W+(P*2)
7) H+(P*3) x W+(P*2)
We get the dimensions of the parts if the material thickness is 20mm:
1) 300x300
2) 300x300
3) 300x300
4) 420x300
5) 420x300
6) 420x340
7) 420x340

Now you can proceed to calculating the bass reflex.

32. The type of bass reflex we will use is rectangular
33. Length. When the end of the bass reflex is offset from the wall of the box
then it is virtually extended, and in fact it turns out that it is tuned to the wrong frequency and is longer WinISD 0.44 does not take this into account; the virtual extension can be calculated by yourself using the formula, but it’s easier to look into the WinISD 0.55a7 program
I repeat: this is only valid when the end of the bass reflex is offset from the wall of the box, and when it protrudes it does not work. So the program WinISD 0.44 shows 28.86 cm and WinISD 0.55a7 25.64 cm. The bass reflex will be installed in part No. 4 420x300 from 420 we subtract 20 this is the height of the bass reflex we get exactly 400 because the rectangular bass reflex is added to another part 8) 300x255

Here are the final dimensions of the parts and their quantity.
1) 300x300
2) 300x300
3) 300x300
4) 400x300
5) 420x300
6) 420x340
7) 420x340
8) 300x255

34. Air resistance. The air resistance in the bass reflex should be made as small as possible by increasing the area of the bass reflex hole.

When making a homemade cabinet subwoofer for a car, the question always arises: how to calculate the cabinet for the subwoofer? To begin with, if the volume is unknown, it is necessary to calculate subwoofer box volume and then, already knowing how to do it subwoofer box calculation.

It can be said with some stretch that when the volume of the body is known, the shape of this body does not affect the sound.

There are various programs for calculating a box for a subwoofer ( program for calculating the subwoofer enclosure– “JBL SpeakerShop” or “Winisd beta.”), but you can simply make the calculation, knowing yourself that the volume is V = h x L x A (where h is the height, L is the length, A is the width).

For example, how to calculate a box for a subwoofer, if for a 12 inch subwoofer (305 mm), the recommended volume is 45 liters. The measured permissible height for the body in a car is 340 mm (h = 340 mm), length 680 mm (L = 680 mm), let's calculate the width.

A=V/L x h

The permissible height (h) for space in the car is h = 340 mm = 34 cm = 0.34 m, and the permissible length L = 680 mm = 68 cm = 0.68 m.

1 liter = 1 10−3 m³ 1 l = 0.001 m³ then V = 45 l = 0.045 m³

Don't forget that there is an internal and external volume, so you need to take into account the thickness of the material from which the subwoofer box is made.

If the box is made of MDF with a thickness of 2 mm (0.02 m), then we reduce the measured values of height and length by the thickness of the MDF on both sides and calculate the internal volume.

h = 0.34m -0.02 x 2= 0.3m; L = 0.68m – 0.04m = 0.64m.

A = V/L x h =0.045m³ /0.3m x 0.64 = 0.234m

The volume that the spacers will have in this case is –V = (0.03 x 0.03 x 0.64) x 4 + (0.03 x 0.03 x 0.24) x 4 = 0.003168 m³. Then we increase the volume of the box by the volume of the spacers. V = 0.048168 m³

A = V/L x h =0.048168m³ /0.3m x 0.64 = 0.2509m

If the volume is increased by the volume of the side struts, then A = 0.255 m.

We want to make a subwoofer enclosure with a slightly inclined front wall, in this case the lengths of the side walls will change: if A = 0.255 m, then A = a + b / 2 = 0.33 + 0.18 /2 = 0.255, that is, reduce the length “b » by the amount by which you increase the value of “a”.

If it is necessary to calculate the volume of a box for a subwoofer of complex shape, for example, the subwoofer body is installed in a wing niche and will have a complex geometric shape, repeating the geometry of the niche, while the rear part of the subwoofer body has different shapes.