Car & Truck Subwoofer Enclosures & Boxes
Subwoofer Enclosures & Boxes: Sealed, Ported, Bandpass & Powered
If you’re into deep, low and vibrating sound, a good subwoofer is a great way to start getting down with your bad self. But to achieve new all-time lows, you need to really get down deeper with a subwoofer box. Add some bass — or a lot of it — to your sound system with the best subwoofer enclosures. We have sealed, ported and bandpass options for all applications.
A subwoofer box is a crucial piece of your stereo puzzle that improves the quality of your audio and gives it a uniform sound. Whatever vehicle, music and subwoofers make up your dream system, OnlineCarStereo.com has a subwoofer enclosure for sale that is a perfect fit for your vehicle, your music and your budget.
Subwoofer Enclosure Boxes
You need more than just a good subwoofer to experience the low end in music and movies. Subwoofer housings contain the audio frequencies that emit from the back of the speaker. Without a subwoofer enclosure, the rear frequencies would cancel out the front frequencies, creating a muddled and dull sound.
Most audio contains low frequencies your stock car audio system can’t accurately reproduce. With the right subwoofer enclosure, your favorite songs will never sound the same — and that’s a good thing. The pre-made subwoofer enclosures and boxes available here are tightly constructed so they deliver all the low notes you’re after. Whether you are searching for subwoofer truck boxes, subwoofer car boxes or waterproof subwoofer boxes for going off-road, our selection includes hundreds of enclosures for cars, trucks and SUVs to optimize the performance of your specific subwoofer.
Enclosures for All Ears
Picking an aftermarket subwoofer enclosure goes beyond saying, “Hey, that looks cool — I want it!” Depending on the vehicle, subwoofer and amplifier you use, you can take your pick of several types of subwoofer enclosures. Sealed subwoofer boxes produce a tighter punch in a small footprint and are excellent for accurately reproducing basslines. The efficient ported subwoofer box, on the other hand, allows you to get the most decibels out of your subwoofer by extracting all of its potential. Bandpass enclosures wedge the woofer between a sealed and ported design to create a hybrid sound that has the qualities of sealed and ported boxes (albeit over a limited frequency range). We also have powered subwoofers that contain an amplifier inside the enclosure for a serious boom. Call our experts at 310-526-8635 for advice on which box is right for your setup.
Universal and Vehicle-Specific Boxes
These boxes come in all sizes and shapes to match your car. Get vehicle-specific subwoofer enclosures designed to fit everything from the cabin of a pickup truck to the trunk of a mid-size. If you have a subwoofer you know you’ll want to bring with you to a future vehicle, order a universal woofer enclosure. Want an all-in-one solution? OnlineCarStereo.com is the place to find pre-paired subwoofers with an enclosure.
Guaranteed to Perform
We carry enclosures with subs and without made by JL Audio, Pioneer, Kicker, Memphis Audio, Ground Shaker and other great brands at great prices. Each one comes with a 60-day money-back guarantee and ships free directly to your door. Shop online 24/7 or visit our brick-and-mortar locations in Southern California for certified installation and expert help.
Car Subwoofer Enclosure FAQs
A subwoofer box helps create better bass. The housing contains the frequencies that emit from the back of the speaker. Without an enclosure, these rear frequencies would cancel out the front frequencies, resulting in a muddled sound.
Yes. Adding a subwoofer enclosure will change the impact the sub has by improving the sound. Different enclosure designs can also make the sound louder or more accurate to suit your music.
MDF, or medium-density fiberboard, is the most popular material. This manufactured wood product is dense, thick and durable, allowing it to stand up to both heavy sound waves and road vibrations. Other effective materials include plywood and fiberglass.
Yes. Some people think bigger is always better since a larger box makes the subwoofer louder. However, the size also affects the sound, and too large a box can lead to jumbled, imprecise audio. We recommend sticking to the subwoofer manufacturer recommendations unless you’re an advanced sound tuner.
This depends on the subwoofer specs (size and output), the vehicle space and the type of sound you want (more slam vs. more precision). Click on the enclosure categories above to learn more about each option.
Car Subwoofers & Boxes at Crutchfield
How to shop for subwoofers and boxes
Adding a subwoofer to your car audio system will let you hear the music that your other speakers can’t reproduce — the low notes from the bass and the power of the kick drum.
Sure, a lot of people like subwoofers for the boom, but any music fan will appreciate what a sub can add. If you like classical music or jazz, a subwoofer is a must if you want to hear the full impact of the performance.
Here we’ll explain the different types of subwoofers that you’ll find on our website. For advice and tips on choosing your subs, read our subwoofer buying guide.
Also referred to as “raw drivers” or “subs”, these are all the actual bass speakers we carry. You can see them all or shop them grouped by size, from 5-1/4″ to 18″. The larger the woofer, the deeper the tones that it can play.
This category contains enclosures already loaded with subwoofers. The advantage? The box is perfectly matched to its sub, which eliminates all the science involved in finding the right enclosure. Just add an amplifier, and you’ll have great bass.
Powered subs are a popular choice for people who want an easy route to adding bass. The subwoofer is mounted in a perfectly matched enclosure, and powered by a built-in amplifier. These all-in-one solutions usually take up less space than the average subwoofer box, so they’re a great choice for smaller vehicles.
Here’s another way to make shopping for a bass system easier. You’ll find a variety of packages here, from simple sub and amp combos to complete systems with the sub(s) already mounted in the box.
Empty subwoofer boxes
Many people prefer the fun of creating their own bass systems. Pick out the sub (or subs) you want and we’ll tell you which boxes they’ll work in. Ditto if you already have your subs. We’ll help you find the right box to make them sound their best.
Custom subwoofer boxes
These boxes are custom designed to fit in existing locations in specific vehicles, like in the rear panel in the back of SUVs and hatchbacks, or under the rear seats of a crew cab truck. The boxes in this category all have a factory-installed subwoofer and some of them even have a built-in amplifier. The easiest way to see if we have a custom subwoofer box for your vehicle is to tell us what you drive.
Custom empty subwoofer boxes
Just like the custom boxes above, these are designed to fit in specific vehicles. They’ll be out of the way so you don’t lose much storage space, if any. The difference is that the boxes in this category are all unloaded. You can pick the sub you want to install.
Some people don’t want to install a sub box, and choose to install smaller subs in the speaker openings in the back of their vehicle, like 6-1/2″ subs on the rear deck, for example. Or, if you have a factory subwoofer that just doesn’t do it for you, and let’s face it, they rarely do, then this category is for you. Tell us about your vehicle, and we’ll show you which subs will fit in your stock speaker locations.
Subwoofers have either one or two voice coils. This is an important feature that greatly impacts the sub’s performance in your audio system.
Some subwoofers are designed to work in tight spaces.
Ported or sealed
A ported box will sound louder and boom. A sealed box delivers tighter, more-focused bass. This is an important detail for getting your music to sound the way you like it.
Subwoofer installation & accessories
Whether you’re building your own box or just need a few accessories to finesse your installation, this is where you’ll find everything from speaker wire to box terminals and port tubes.
Subwoofer box: Bass reflex, closed box, comparison
Automotive subwoofer OEM Audison
In car audio, there are many options for acoustic box designs. Therefore, many beginners do not know what is best to choose. The most popular types of boxes for a subwoofer are a closed box and a phase inverter.
And there are also such designs as bandpass, quarter-wave resonator, freeair and others, but when building systems they are used extremely rarely for various reasons. It is up to the owner of the speaker to decide which subwoofer box to choose based on sound requirements and experience.
We advise you to pay attention to the article from what material is better to make a subwoofer box. We have clearly demonstrated how the rigidity of the box affects the quality and volume of the bass. Hertz Subwoofer
21 Phase inverter
How much duct volume is required for a phase inverter? What determines the setting of the PHI box Conclusion
This type of design is the simplest. A closed box for a subwoofer is easy to calculate and assemble. Its design is a box of several walls, most often of 6.
Car acoustics Ural
Advantages of SL:
- Simple calculation;
- Easy assembly;
- Small volume of the finished box, and therefore compact;
- Good impulsive characteristics;
- Fast and clear bass. Plays club tracks well.
The closed box has only one drawback, but sometimes it is decisive. This type of design has a very low level of efficiency relative to other boxes. A closed box is not suitable for those who want high sound pressure.
However, it is suitable for fans of rock, club music, jazz and the like. If a person wants bass, but needs space in the trunk, then a closed box is ideal. A closed box will play poorly if the wrong volume is selected. What volume of the box is needed for this type of design has long been decided by experienced people in car audio through calculations and experiments. Volume selection will depend on the size of the subwoofer.
The most common speaker sizes are: 6, 8, 10, 12, 15, 18 inches. But you can also find speakers of other sizes, as a rule, they are used very rarely in installations. Subwoofers with a diameter of 6 inches are produced by several companies and are also rare in installations. Most people choose speakers with a diameter of 8-18 inches. Some people give the diameter of the subwoofer in centimeters, which is not entirely correct. In professional car audio, it is customary to express dimensions in inches.
Bluetooth-AUX car receiver adapter
Recommended volume for subwoofer closed box: inch (25 cm) 13-23 liters net volume,
for 12″ (30 cm) 24-37 liters net volume, for 15″ (38 cm) 38-57 liters net volume a for 18″ (46 cm) will require 58-80 liters.
The volume is given as an approximation, as for each loudspeaker you need to choose a certain volume, based on its characteristics. The setting of a closed box will depend on its volume. The larger the volume of the box, the lower the tuning frequency of the box, the bass will be softer. The smaller the volume of the box, the higher the frequency of the box, the bass will be clearer and faster. Do not increase or decrease the volume too much, as this is fraught with consequences. When calculating the box, adhere to the volume that was decreed above. If there is a search for volume, then the bass will turn out to be vague, fuzzy. If the volume is not enough, then the bass will be very fast and “hammer” on the ears in the worst sense of the word.
A lot depends on the box setting, but no less important point is “Radio setup”.
This type of design is quite difficult to calculate and build. Its design is significantly different from the closed box. However, it has advantages, namely:
Microfibre car towel
- High level of efficiency. The phase inverter will reproduce low frequencies much louder than a closed box;
- Simple case calculation;
- Reconfiguration if necessary. This is especially important for beginners;
- Good speaker cooling.
Also, the phase inverter also has disadvantages, the number of which is greater than that of the SG. So, the cons:
- FI is louder than the SL, but the bass here is no longer so clear and fast;
- The dimensions of the FI box are much larger compared to the SG;
- Large capacity. Because of this, the finished box will take up more space in the trunk.
Stove for additional heating of the car interior
Based on the advantages and disadvantages, you can understand where the FI boxes are used. Most often they are used in installations where loud and pronounced bass is needed. The phase inverter is suitable for listeners of any rap, electronic and club music. And also it is suitable for those who do not need free space in the trunk, as the box will occupy almost the entire space.
The FI box will help you get more bass than in the TH from a small diameter speaker. However, this will require much more space.
Bluetooth receiver adapter for car radio AUX
What volume of box is required for a phase inverter?
- an 8 inch (20 cm) subwoofer will need 20-33 liters of net volume;
- for 10″ speaker (25 cm) – 34-46 liters,
- for 12″ (30 cm) – 47-78 liters,
- for 15″ (38 cm) – 79-120 liters
- and for an 18-inch subwoofer (46 cm) you need 120-170 liters.
As in the case of SL, the numbers given here are imprecise. However, in the FI case, you can “play” with the volume and take a value less than the recommended ones, finding out at what volume the subwoofer plays better. But do not increase or shrink the volume too much, this can lead to a loss of power and speaker failure. It is best to rely on the recommendations of the subwoofer manufacturer.
Car DVR mirror 3 in 1
What determines the setting of the FI box
The larger the volume of the box, the lower the tuning frequency will be, the bass speed will decrease. If you need a higher frequency, then the volume must be reduced. If your amplifier power rating exceeds the speaker rating, then it is recommended to make the volume smaller. This is necessary in order to distribute the load on the speaker and prevent it from exceeding the stroke. If the amplifier is weaker than the speaker, then we recommend making the volume of the box a little larger. This compensates for the volume due to the lack of power.
Port area should also depend on volume. Average speaker port area values are: 002 for 12″ – 140-270 cm2,
for 15″ – 240-420 cm2,
for 18″ – 360-580 cm2
The length of the port also affects the tuning frequency of the subwoofer box, the longer the port, the lower the box setting, the shorter the port, respectively, the tuning frequency is higher. When calculating a box for a subwoofer, first of all, you need to familiarize yourself with the characteristics of the speaker and the recommended box parameters. In some cases, the manufacturer recommends completely different box parameters than those given in the article. The speaker may have non-standard characteristics, because of which it will require a specific box. Such a subwoofer is most often found in Kicker and DD manufacturing companies. However, other manufacturers also have such speakers, but in much smaller quantities.
Volumes are approximate, from and to. It will differ depending on the speaker, but as a rule they will be in the same plug … For example, for a 12 inch subwoofer, this is 47-78 liters and the port will be from 140 to 270 square meters. see, and how to calculate the volume in more detail, we will study all this in subsequent articles. We hope that this article answered your question, if you have any comments or suggestions, you can leave your comment below.
The information you have learned is perfect for those who want to learn how to count boxes on their own.
We put a lot of effort into creating this article, trying to write it in a simple and understandable language. But it is up to you to decide if we did it or not. If you still have questions, create a topic on the “Forum”, we and our friendly community will discuss all the details and find the best answer to it.
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Car wash brush Sponge, water dispenser
How to fill closed drawers | magazine AvtoZvuk
If you thought that this is a continuation of the old bodyagi, which has not subsided to this day, about synthetic winterizers, activated carbon and so on, then you were mistaken. Enough to stir up the old synthetic winterizer…
The provocative factor for this small (so far) research was the story about the German autosonic athlete Mike Hook, the first mention of the crazy creativity of which is in the material about the Eurofinal EMMA 2008 (the link is at the very bottom) . Namely, that in order (as the madman claimed) to optimize the working conditions of mid-bass speakers, their boxes were filled with gas, according to characteristics much different from air. Simple investigative actions revealed the name of the gas (it is long – sulfur hexafluoride) and the chemical formula (it is short – SF 6 ), and at the same time gave rise to the question: who, in fact, came up with this? And when? And why, because the only known at that time case of using an alternative gas to air in acoustics was clearly meaningless: the Focal 13 WS used by Kryuk quietly works in a closed volume of 3-5 liters and without any perversions.
The fact that it was not Hook who came up with this, and not even his 500 times more educated friend Elmar Michels, who submitted the idea of SF 6 (so short, right?), It was intuitively clear. And it was indirectly confirmed pretty soon: I told Dmitry Svoboda about this story, who reacted immediately: “I remember that about 15 years ago, Gaidarov and I dragged a cylinder with this hexafluoride from Nizhny Novgorod, we suffered then: they don’t take it in luggage, they take it into the cabin with them they don’t let them in anymore . .. ”The idea, it turns out, to put it mildly, is not yesterday’s. And when? Or, more generally, has it been proposed, for acoustic reasons, to use something other than air in the acoustic design? The answer is clear even before looking for it: for sure. Then it remains: when, by whom, why and how in a broad, global sense.
Hexafluoride, damn it
Let’s just say that all the inventions regarding the replacement of air in acoustic design with something else were made for the sole purpose of making the design more compact. And why is it non-compact (so far, to highlight the essence of the idea, we are talking about SL, although some of the innovations proposed at different times were applicable to FI)? Because the smaller the volume of the closed box, the more rigid the “air spring” becomes – the elasticity of the air in the box, which works in parallel with the elasticity of the head suspension. And this means an inevitable increase in the resonant frequency of the head and immediately – the lower limit of its frequency range. The rigidity of a gas volume depends on several characteristics of the medium: adiabatic index Cp/Cv, speed of sound and density. While mainly air remained inside the ZY, bright minds mainly affected the first of the mentioned characteristics, it is it that changes when the box is filled with all sorts of fibrous materials or at least activated carbon, as KEF does. But there were other proposals that went beyond the air environment. The already mentioned SF 6 the density is exactly five times greater than that of air, and the speed of sound in it is 2.5 times less.
It is the last circumstance that determines effective (and completely safe) tricks with inhalation of SF 6 , after that, and before the self-cleaning of the lungs, the inhaler speaks an octave or more lower than he intended. The arithmetic is simple: the wavelength in SF 6 is 2.5 times less than in air, and all the resonators in the voice apparatus of a mere mortal turn out to be tuned to a frequency 2. 5 times lower.
But back to acoustics. The very first mention of magic gas that could be found dates back to 1957. The author, a certain Herbert Sullivan, wrote bluntly and openly half a century ago: “The internal volume of a box or horn is filled with a heavy gas, such as SF 6 “. The inventor’s task was, while maintaining the geometric dimensions of a box with a conventional dynamic head, to lower the resonant frequency, and in the case of a horn loudspeaker, to make the horn shorter while maintaining all acoustic characteristics. To do this, all volumes in contact with the radiating element were filled with gas (you already know which one), and in order to keep the gas inside the horn or in front of the speaker cone, it was proposed to cover the outlet here and there with a flexible film, gas-tight, but transparent to sound. If in scrap, continued Mr. Sullivan in perfect English, gas can only be pumped into the box, he even carefully added a filling fitting to all the sketches. In this case, however, he promised a smaller effect (Fig. 1).
It cannot be said that the inventor went deeply into the physics of the process, his statements are rather declarative. According to the personal ideas about the acoustics of the author of these lines (who has the constitutional right to make mistakes), it turns out that in the case of a horn, everything should work, but in the case of SL – somehow not very much. The fact is that in the formulas of elasticity of the air volume known to the author, the product of density and the square of the speed of sound appears, and this product for SF 6 is not much different from the same for air. Here, where the wave process is another matter, there the first game is played by the speed of sound, and you know what it is.
More than ten years later, another bright mind, Bernhart Eisman Jr. (I can imagine what Aizman Sr. came up with), suggested pumping both behind the diffuser and in front of it another gas, even to choose from a family of fluorine-containing derivatives of hydrocarbons, now better known (and under this name cursed by environmentalists) as freons. Aizman Jr. he worked for the DuPont company, which, in fact, owns the Freon trademark, so he had at least filled up with gases for experiments. Just fill up: in his patent application (later granted), the inventor gives touching examples of experiments confirming his correctness. For example: a transistor receiver is placed in a box (at 19’68 was like the iPod now, only without the headphones. — Approx. for the mol. read.), gas is literally poured into the box from the cylinder, which is significantly heavier than air, so it does not go anywhere. Aizman Jr. states: “Even untrained listeners unanimously noted a significant improvement in sound quality.” On the experimental setup shown in Fig. 2, he also received the frequency response, where he noted an improvement in the reproduction of both low and high frequencies. The upper curve is the original one, the middle one is when the gas that is detrimental to the ozone layer is pumped behind the speaker, the lower one is when it is also in front of the diffuser, and in order not to be blown out by a draft, a thin lavsan film is stretched on top.
There are other proposals for replacing air with other gases, of varying degrees of indistinctness. Paradoxically, much more robust, and most importantly – tested in practice, innovations are much more radical. There, the air is replaced by another, but not even gas…
…and gas condensate
Previously, the volume of its production was reported in the program “Vremya” in the amount of oil. Now they are kind of silent. And we will talk. Let’s start, as in the program “Vremya”, with news around the country, then – to international ones. A few years ago, at the Russian High End exhibition, the development of our compatriot Ivan Vozhenin was shown. A small, oversized speaker, the subwoofer played like a big one in the most mysterious and impressive way. When asked how, they say, so, the inventor answered that inside there was a special environment that had nothing to do with the Moscow air at all, and which one he would not say at all, a secret, a patent, geben Sie mir bitte, otherwise I would not say anything. However, Ivan Nikitich craved not only national, but also international fame and fortune, and therefore registered his invention outside his beloved homeland. And there the conversation is simple: patented – so let everyone see what he patented. And look, this is rice. 3. Case, speaker, this is understandable. From the incomprehensible: 4 is a kind of liquid poured into the body; 5 is the result of its evaporation, moreover, in a saturated state. And position 3 is a combination of a heat accumulator with a radiator.
How does it all work (this time it works, not “should have”)? That’s how. We return to the damned elasticity of the air in the box. She after all, actually, as is shown? Here, for example, the diffuser went back, reducing the volume of air behind him. The pressure there has built up and is pushing him in the back, preventing him from moving. If the box is large, the change in volume by a percentage and the pressure will raise by a percentage with a penny, it pushes slightly, the rigidity is small, the resonance frequency rises a little. In a small box, the same displacement of the diffuser will change the volume by five, say, percent, and the resistance of the increased pressure inside will be just as stronger. All “gas substitutes” fought for the same volume change to cause a smaller pressure change. But everything they could (ideally) achieve – adding aggregates or even replacing gas – was measured in the first tens of percent. But there were also radicals, here is the most striking example, there is no other like it. One Swiss (the surname is in the editorial office, it does not matter now) proposed to break the connection between volume and pressure with the help of modern electronics. Encroached, one might say, on the sacred bonds blessed by Boyle, Mariotte and other ministers of science.
He suggested a strange thing: in the loudspeaker housing (Fig. 4) there is a high-speed pressure sensor. The diffuser went back, as in the previous example, the pressure in the housing also went up, the sensor sensed this and gave a command to correct the pressure. This signal is amplified and fed to the voice coil of another speaker, placed in an additional closed volume, very small. His diffuser also went back, just enough so that the pressure change was minimal (theoretically – zero, but there is always a control error). The auxiliary speaker, which has a very small volume of its own closed box, will have to overcome much stronger resistance: the rigidity of its “air spring” is enormous. “I don’t give a damn,” says the inventor. – The amplifier is meaner – and let it try. He is here – the maintenance staff, optimizing the operation of the main speaker. This is a super-radical solution, theoretically, if we consider that there are no errors in the control system, no inertia, such a design means the volume of a closed box, equivalent to an infinite one, regardless of its physical volume. Smart electronics and additional energy costs are thrown into the irreconcilable struggle with Boyle and Marriott. This, as was said, is an extreme brute-force solution. What Vozhenin proposed, and as we will soon see – he is not entirely alone, is much more elegant.
Here the struggle with the laws of the gaseous state goes on without the expenditure of energy from the outside. The idea is the following. It is necessary to find a substance that at room temperature and normal atmospheric pressure could be in a state of equilibrium “liquid – saturated vapor.” With the modern development of chemistry, this is certainly possible. Such a two-phase mixture is located inside the GW. Silence, calmness, complete balance. Here comes the music lover, turns on the music, and the balance – kranty. Here again, for the umpteenth time today, the industrious diffuser went back, reducing the volume of no longer air, but steam inside the case. The pressure inside begins to grow, but as the pressure rises, the vapor begins to condense into a liquid, with a decrease in volume by hundreds of times. Ten cubic centimeters of steam condensed, and it turned out to be seven hundred times smaller volume of slurry at the bottom. And since the gas (well, steam, it is also a gas in its own way) has become less in volume, it means that the pressure has almost not increased. The diffuser went forward from the neutral position. The pressure inside has dropped, the resulting rarefaction should have pulled the diffuser back, but then the liquid reacts to the reduced pressure, boiling vigorously, part of it turns into steam, restoring balance. Do you understand the mechanism? For any change in volume caused by the movement of the diffuser, the medium inside responds to its own, caused by repeated acts of condensation and evaporation, strictly in antiphase.
Who thought of this? I respect domestic inventors, but skeptical experience gloatingly whispers in my ear: “this is unlikely.” Invention is like that. Something “characterized by the fact that …” appeared in the device, and hello, it is considered a new development. In the design developed (and tested, we note) by Ivan Vozhenin, “different” is a heat accumulator with a developed heat exchange surface, which optimizes the process of phase transformations. Has anyone else worked on this? But what about …
What was, what will be
One, indirect mention of such a method of manipulating the volume of the SG has already appeared on the pages of this section, however – in passing. The possibility of using two-phase loudspeaker volume filling was mentioned in his 1978 patent by Eugene Chervinsky (nicknamed Cerwin-Vega! The exclamation mark is mandatory, otherwise it does not respond).
You see (Fig. 5), there is liquid, and a gas-tight film around the speaker, and even a device for bringing the liquid to operating temperature. Owners of lamp technology are no strangers. But there it was “and also in the case when …”.
A year before, someone James Ott pointed out in plain text to phase transformations as the main subject of the invention.
Here (Fig. 6), the liquid and saturated vapor, into which it was supposed to turn in time with the flutter of the diffuser, were placed in a soft bag at the bottom of the loudspeaker housing and were also brought to working condition by a heater switched on from the sound pressure sensor. That’s when it was invented. Thirty years ago, yes.
Further searches determined the size of the hook. Philips also claims priority in vapor-liquid acoustics (Fig. 7). There (this is 1963) a two-phase mixture was placed in something like a bellows. Gak grew, but, as it turned out, did not reach the final size of forty years.
1938 Even before the war, but already under Hitler, an engineer from Telefunken Gesellschaft m.b.H. Erich Theinhouse drew this cute picture (fig. 8) and accompanied it with detailed explanations.
I read in English because Teenhouse patented his brainchild in the US as well – marvelous literature, and extremely instructive. For example, loud-speaker was still written with a hyphen (9 years have passed since the invention of what we call “speaker”, but the term high-fidelity was found in the text, also with a hyphen. The essence of the matter turned out to be exactly the same as seven decades later. Only instead of a closed box, which, as you know (“A3” No. 2/2006) came into use only in the 50s, it was about bulky acoustic screens and cases, but open. The inventor lamented that it would be good, of course, to close the speaker at the back to block an acoustic short circuit. But the trouble is, you can’t – there is air, he, he, the bastard, is hard, and then – the resonant frequency … Oh, no, there has never been such an expression. “Natural period” – well, not lovely?
So let’s, the German suggested, let’s make a very small box, and pour liquid behind the diffuser, which will be in peace and harmony with its saturated steam. And there will be no change in pressure with each stroke of the diffuser, and the “natural period” will remain what it was. And the curved tube that attracted your immediate attention (it could not but attract, there is nothing more in the figure) is a means of adjusting the system to the current atmospheric pressure. Without any electronics, just filled with water.