The horn does not work. Information loudspeaker horn

26.09.2020

About pipes and whistles

How a Horn Works with the Edge EDPRO45T HF Transmitter

Recently, in one of the conversations, a question was asked about how a high-frequency device with a horn design works. There was an idea to find some kind of emitter with a removable "pipe" and see what he can do with it and without it.

How a Horn Compression Radiator Works

The name is serious, but, in fact, we are dealing with an ordinary speaker. Look at the other side - a conventional magnetic system.

Only, unlike a conventional speaker, the voice coil pushes not the diffuser, but the metal membrane. The membrane is located inside the body, and sound vibrations are not emitted immediately into the open space, but are "pushed" through a small hole (in fact, this is why the emitter is called compression). At the exit of this hole, the horn is placed.

To understand what a mouthpiece is for, here's a good example. Go out to the balcony and shout something. While the neighbors are freaking out, continue the experiment - take a thick paper magazine, roll it up in a cone, and shout through it. Now, urgently leave the balcony, until you have been called "durku", and draw conclusions.

There are at least two of them. First, it got louder with the mouthpiece. This means that a higher sound pressure can be obtained with the same supplied power. Secondly, the timbre of the voice changed with the horn. This means that the frequency response can be corrected by the shape of the "pipe". That's enough for a start. Now let's look at the same with a specific example.

Experiments

Strictly speaking, when we remove the plastic horn from the Edge EDPRO45T, we don't completely lose the horn. The radiating membrane itself is located deep inside the case, so it would be more correct to speak - with a short horn and with a large horn.

So, the first thing we do is look to see if the horn affects the impedance of the speaker. The blue curve is without the twisted "pipe", the green one is all assembled.

As you can see, the difference, though small, is still there. This is because the horn acoustically loads the radiating membrane. The air mass in the short horn and in the long horn will "resist" the movement of the membrane in different ways. By the way, one of the points is whether the horn exit is smoothly rounded or has sharp edges. This also makes its own adjustments to the behavior of the air mass inside the horn.

Now we look at the frequency response along the axis and at an angle. The red curve - without the twisted "pipe", the green one - everything is assembled:

AFC along the axis. Green curve - complete structure

Frequency response at an angle of 45 degrees. Green curve - complete structure

As you can see, it really turns out louder with a horn, and at the same time the frequency response becomes less clumsy. Here is a confirmation of what was said earlier about improving efficiency and correcting the frequency response.

How to turn disadvantages into advantages

Since the speakers were still in my hands, I decided to experiment a little more. Well, I didn't like this hump around 2 kHz. He did not promise anything good for the sound. I turn on the emitter through a simple first-order filter. Who did not understand - through an ordinary capacitor. See how this affected the frequency response. At the lower end of the range, it dropped slightly, leaving everything as it is at the top. It became very good:

Green curve - own frequency response of the emitter
Blue curve - with a 3.3 μF capacitor connected in series,
Purple curve - with 4.7 μF capacitor in series:

The driver emits efficiently, starting from 1.5-2 kHz. By the way, you can keep this option in mind if the midrange speakers are "deaf" and reluctant to work above 1-2 kHz, like the same or.

Ajoutée 9 août 2017

Why do horns sound loud, but they are so little used in electroacoustics, that is, in speakers? More recently, horns have been used everywhere: both in gramophones and in gramophones. In squares, parks and train stations, important messages sounded from horns and music was played. However, it turned out that the mouthpiece ... Uh, no, what next about the mouthpiece you will learn by watching the film “The Shoutbox”. As always, amusing, fun and informative. Incredible adventures, amazing rescue and a happy ending. This is an adventure-theoretical epic.
This film tells about the principle of operation of a horn, about their types, forms of forming, which of them are the most optimal and the best, what size horns should be, what efficiency of horns, why a horn is called an acoustic transformer, how to arrange volumes in front and behind a diffuser, and much other. In total, of course, it was not possible to tell about the horns in such a small film, but at last you will find out why the horn is louder and why we do not need such happiness.
Synopsis. In the raging sea, two ships are rushing towards each other, driven by the elements, and it seemed that death was inevitable, but ...
Sir, take the trumpet.
Recommended article: Bjørn Kolbrek, "Horn Theory"
www.grc.com/acoustics/an-introduction-to-horn-theory.pdf
Support channel - www.patreon.com/ensemb
# audio # acoustics # sound # horn

Commentaires

you can immediately see the video editing, the waves are around and the person stands rooted to the spot.

Strange guy .. very strange

You didn’t understand a hundredth part of the diffusoria, Heeee)) (because you were tired)

Interesting

After Netrebko rolled her eyes ... but the shout went to the ass !!!

Oh, how she sang!

Anchor in * opu 😅😅😅 Ugarnul))) and, by the way, soon there will be 100 thousand of us 👍 keep it up

someday, if it doesn't sink into the depths of YouTube, these videos will be classics!

Shout, OYa. ZYa have already been. Can you make a video about the phase-inverter design of the speaker and why you don't like it? Thank you in advance.

It became clearer enough than he himself was looking for similar information on the Internet.There are several car horn sirens in stocks and decided to remake them for warning in front of the house And it turned out that at high volume levels, the distortions are huge and put the idea aside

Also tsіkavі your sub "Active savor of that іinshoї speeches, diagrams, etc.

I can’t say that the horn is used a little. very even and moreover in all three ranges of the midrange, though less often. They are distinguished by a sharp front, high efficiency and the absence of diseases of the PD and PI. There is no buzz like FI, which is very pleasant when listening to rock and classics. in 2010 I assembled scoops for myself under 15 heads and I am very satisfied. I will not return to FI and ZYa. A huge disadvantage is its huge size and weight. In combination with the triamp system, the mustache is quite transparent.

In 20 minutes, explaining so much about the mouthpieces to a person who did not know anything about it (to me) is truly a titanic job. Of course, as you said, 1/100 is not, but I think over time you will reach 100/100 !!

Can you clarify one point why, when replacing horn HF drivers, the manufacturer recommends in the service manual to test these drivers at a frequency of 1-3 kHz, although they actually work in the 8-20 kHz band? Is the test to be carried out using a network (crossover) and with accurate acoustic matching in a pair?

Among car audio enthusiasts, there is a point of view that if the efficiency of the speaker is 1%, then all the remaining 99% of the input power is used to warm up the voice coil. I have been explaining for many years that this is not true. That the loudspeaker head is a double-acting serial transducer: electromechanical and mechanoacoustic. That is, first, electrical energy is converted into mechanical energy. Here, the order of losses is approximately the same as in an electric motor, that is, they are small, up to 10-20%. This is the loss for warming up the voice coil, for overcoming friction forces in the suspension elements, centering washers, etc. But then the mechanical energy of the diffuser movement is converted into acoustic energy, and it is here that the greatest losses in efficiency are due to the low resistance of the medium. However, not everyone accepts this fact, and the most persistent continue to persist, they say, bullshit, all the power goes to warm up the coil. Then an experiment was set up, proving that the problem was precisely in the environment. The logic is simple: we take two identical speakers and attach them "face to face" at a very short distance. I had it 0.5 cm between the flanges. It turned out to be such a "push-push" with a connecting layer of air. We connect one speaker to the output of the amplifier, and the voice coil of the other is simply short-circuited with a small resistance of the ammeter. If the speaker is a bad electromechanical converter, and almost all the energy goes into heating the coil, then the speaker will give out very weak vibrations to the external environment, and the second will weaken them even more, and the current through the coil of the driven speaker will be scanty compared to the current through the coil the "leading" speaker. If now a sinusoidal signal is applied to the first speaker, then it will swing the diffuser of the second speaker, and by the current through the ammeter we can judge what order the losses will be after the two speakers convert electrical energy into electrical energy. So, experience has shown that the current in the voice coil of the slave speaker is not much less than the current in the coil of the master speaker. At different frequencies, the efficiency of this "push-pull" was different, but not 1%, but ten times more, reaching 80% at some frequencies. Up to 80%, Karl! This clearly indicates that as an electromechanical transducer, the speaker is very efficient, and about 99% of the heat loss in the coil is out of the question. Anyone can repeat this experience with any woofer. I did this twice: with 8GD-1 and 30GD-2B (75GDN-1-4). In this video, Alexander explained why the speaker poorly converts electrical energy into acoustic energy. If it gets noticed by the wide masses of "column builders and sub builders" it will be great.

Pyramid shape - for a larger EMR wave. The top and ribs are breakwaters, transmit vibrations to the center of the base, according to the principle of the horn (the forces of electromagnetic oscillations of a sound wave, through air molecules, are transmitted to the material of the walls of the horn; resistance to this force gives additional oscillations of the charges of the substance of the walls with the same frequency - the sound is amplified) ...

I created a 3D model of a horn stand for a meizu m6 note smartphone, printed it on a 3D printer and the result just amazed me ... No one has come to life with such imaginations! Sounds much better, louder, more beautiful. For anyone interested, you can try the stand on the same phone, I laid it out on 3d today for free access. But I will try to fit only one phone (name above) instructions for printing are described there.

Clownery. Info useful person literate interesting to listen to BUT DO NOT LOOK!

separate channel for horns!

An almost endless trumpet with a horn? ... So it's a contrabassoon! :)

What if we change the acoustic impedance of the medium? How will the speaker behave in an atmosphere of carbon dioxide, or even denser gas? I recently saw a video with a speaker under water, but everything was up to par or not. And what will happen to the sound when we cross the border of two environments, otherwise we will not breathe comfortably in a CO2 atmosphere.

Interesting and unusual video shooting at open aperture. A sort of bokeh video))) Well, the content is cool!

Hello. Tell me, pzhl, your opinion regarding this miracle. Triad Cinema Reference CR-1 The cost of such things does not allow you to quickly find out what is inside, and the overwhelming majority will not be able to stroke it (let alone turn it on). Question: is a circuit viable, made of components, one hundred times cheaper, including a case and, or wood, chipboard, etc.? Does it lose its meaning, i.e. scheme? ..Not a method, is it the Chinese comrades, it is true, with a different motive, but the same goal? And what should be inside, add. fi, filter? THX. Sorry, my inattention if I asked questions, the answers to which were in your video. I am a layman in this.

We put the woofer in the upper corners of the room and don't bother with theory. Checkmate music lovers. With such a speaker everything is fine, except for one but catastrophic drawback: it cannot be sold.

I am not an engineer or an electrician, but I am assembling a sub because I want to. And I want to do it well. I need advice both on the body and on the components, please, sympathizers and those who are interested ..

Opera singers have noble mouthpieces ...

It would be great to add a normal Russian-language support method in addition to patreon. I am sure the number of donations will increase. Three factors scared me in turn: 1 English-speaking 2 The need for registration 3 Regularity of contributions.

That is, in water, a regular speaker will be much louder? It has more density than air.

We are waiting for the continuation of stories about horns.

And this is for those who are really interested in mouthpieces. hornresp.net/

You would have to make teeth, it would be generally good. all the same 65K subscribers, you need to preen
Shout out to you in ...))) in lzh
Very interesting. This year, the problem on the horns was given to the tournament of young physicists (iypt.org), I will show all newcomers your video so that you have a place to start.
Well done!!!)
Parfenov 2 !!!
The video is interesting. on theatrical))
Alexander, and the topic has not been disclosed ... You don’t count?
that feeling that raised aikyu by another 10 points
Interestingly clever :) Thank you very much for the video! In places it is difficult, but over time you begin to understand.
I watched several videos about acoustics and only now guessed to set the playback speed to 1.25
accidentally attacked your channel ... but mulberries ... watch do not revise)
STRONG CONTENT !!!
40 percent of information for me is a matrix :)))) but Voight's pipes are at home and delight every day
Alexander, please tell me what kind of high-frequency speaker can I replace my own in Amfiton 25AS-027? The choice is between the usual buzzer from acoustics from the musical center SONY, PANASONIC, JVC, AIWA 1998-2006. and a high-frequency driver from floor-standing speakers with large woofers (10, 12, 15 inches) ... or maybe you would advise something else .. Thank you.
Wow! Anchor you in the rectum! I'm signing up here, do you understand, and you give me a small cart instead of a carriage ??? (joke, jellyfish by your collar) Very interesting! Thanks!
man well done. all videos are super.
I made myself a horn box in a car for a subwoofer, the length of the horn itself is 170cm, but this is not an ordinary horn, but the so-called back-loaded (there is a volume for the subwoofer and then there is a port (horn). I play such a box from 24Hz to 50Hz +. Today I measured the result of 139.8 dB (there is little power)
Yes, the topic of boobs is not covered.
Some kind of mysticism: I hardly learn anything new, but I listen, I listen .. Hypnosis? It's better at a speed of 1.25 :-)
funktione one - real working horn cluster concert systems. Their 21 "driver horn subs sound really cool.
Tell us more specifically about Reverse-loaded horns (low-frequency)
yeah) are ineffective at low frequencies) but what about concert albums like cervin vega ts42)))) chuika 108dbs / w / m, in comparison with zia / phi 100-103 with the same 21 "speakers in zia / fi) well, yes, 6-8db difference chuiki is nothing) lol))) yeah and 10% efficiency for low-frequency horns, yeah, and concert horn stacks are not considered acoustics anymore? cm on a sub already under 112-114 dB, this is exactly the same 30-50% efficiency, another question is that you can't put such acoustics at home, but still the numbers are quite real

We traditionally use a horn to amplify our voice. It is believed that this device, directing sound in a certain direction, does not allow it to scatter. In reality, however, a mouthpiece is not just an ordinary hub.

Acoustic energy is taken from a source by a horn and concentrated into a narrow beam. In reality, however, a mouthpiece is not just an ordinary hub. It is much more efficient. It adds to the sound a power that is uncharacteristic for him hitherto. Lord Rayleigh also developed a theory of sound. He argued that for a sharp cone, the intensity increases not only due to concentration, or a change in the angle of radiation within which the sound travels.
This increases the energy that the source emits. By reducing the angle at which the horn is deployed, Rayleigh says, you can get any amount of energy you want from the sound source. In this case, due to the lengthening of the horn, the release of the above energy into the environment is facilitated. One can agree with his theory! But why is this happening?

Let's see how you can radiate sound as efficiently as possible. The sound wave is not so easy to generate. As a rule, it is produced by oscillating membranes: say, a speaker cone. It invariably possesses a pair of sound-emitting surfaces.
The radiation is in antiphase - for obvious geometric reasons. Compressing air on one side, the diffuser always discharges it on the other. So the speaker, in fact, is two sound sources located on opposite sides of the diffuser and emitting sound in antiphase.
The problem is just a pair of sources in antiphase. After all, the sound wave in this case does not propagate into space, but is closed between the sources. Take low frequency vibrations as an example. The forward-moving speaker diffuser, in theory, compresses the air in front of it, thinning it behind itself.
However, in our case, the air will follow a simple path: it will flow to the back of the diffuser from the front in a circle. The latter, at the same time, without feeling air resistance, as it were, vibrates in a vacuum. Result: regardless of the power of the sound source, all its power can be spent on compressing the air, which simply flows around the radiator under this pressure.
This air flow around the diffuser is just that very strong sound wave radiated from one side to the other. Similarly, the sounds of other frequencies are closed. Their waves will fit on the road from the front to the back of the membrane a whole number of times. The process is called "acoustic short circuit".
As a result, the sound emitted by the speaker is absorbed by it along a closed path of arbitrary length. If such a "short circuit" occurs, the speaker stops emitting sound, vibrating, as mentioned above, without feeling the air, practically in a vacuum. It can occur both from one side to the other, and generally on one side. The latter option is possible in the presence of external obstacles. It is also possible to short-circuit a pair of different speakers between the diffusers.
It is possible to deal with a short circuit in a pair of sides of one diffuser by increasing its diameter. Indeed, in this case, the path of bending will also increase. It is then easier for the air in the center of the diffuser to be compressed rather than flowing around it. At the edges, however, the acoustic closure will still remain. The well-known rule of thumb for increasing radiation efficiency is this: for lower sounds, a larger diffuser is needed.
It is possible not to enlarge the diffuser, but to place it in the wall, which, of course, emits sound, but also prevents acoustic closure. You can go further by isolating the front and rear diffuser surfaces from each other. The speaker is inserted into the most ordinary speaker or closed box.

Curiously, even if the vibration amplitude is small, the speaker in the box emits sound more efficiently than its counterpart without the box. Even if the latter has a more powerful amplitude. Strange, isn't it?
It seems that the vibrational amplitude of the diffuser depends on the same parameter of the sound wave ... Yes, the sound of an open speaker is very powerful. However, having closed from one side to the other, it hovers around the speaker without taking away the energy. The speaker in the box has a lower oscillatory amplitude. But all the available sound goes out.
The drawer drawback is still quite weighty. The sound emitted by the back side of the diffuser disappears, being closed in this box. After all, as a rule, its inner part is upholstered with material that absorbs sounds. So the sound inside the walls, without re-reflection, is banally absorbed. Regarding the dynamics, this interior turns out to be an endless space, radiating "reverse" sounding without any benefit. Compared to acoustic short circuiting, this is not bad. It does not absorb all the sound, but exactly half - which is also unacceptable.
The box can be evacuated to suppress radiation from the back of the diffuser. Maybe it will be possible to do this when they come up with boxes that can withstand atmospheric pressure.

How can you use the radiation from the back of the speaker to your advantage? It seems to be the easiest way to unfold this radiation by one hundred and eighty degrees, adding it to the straight line. You can use a pipe for this. The sound coming out of the trumpet must be a copy of its counterpart coming out of the front of the speaker. Then the powers of both sounds will add up, and an acoustic short circuit will not happen.
The full implementation of this idea is unrealistic: the sound always comes out of the pipe with a delay, being, moreover, inverted. After all, they remove it from the back of the diffuser. This is not a problem for a signal that is stable over time. For example, if it is a sinusoid with a fixed frequency.
The inverted sinusoid, delayed by half a wave, coincides with its direct analogue. Therefore, by correctly delaying the return sound, we will compensate for its inversion. This is how a pair of synchronous sound sources is formed - a pipe with a diffuser. Signal inversion is achieved with a phase delay, and the consequence is a phase inverter. Compared to the box, the capacity will double. You can adjust the amount of delay by changing the length of the pipe.
However, different frequencies need pipes of different lengths. In other words, there is no delay in combining a complex inverted signal with a direct signal. So a pipe like this will work well with only one tuning frequency and its harmonics. There is no benefit for other frequencies. If the frequencies are between the harmonics of the tuning frequency, the effect will be generally negative. The result is a short acoustic circuit. As a rule, this pipe works only at a tuning frequency, and quite low.
It is important that the lower frequencies that give the pipe a short circuit are not heard, and ideally they are completely absent. To avoid shorting the pipe at frequencies exceeding the tuning frequency, it is produced by cranking, then upholstery with material that absorbs sounds. Then relatively high sounds will not pass through it, and the box will seem closed to them.

With the help of the phase inverter, you can take advantage of the reverse sound particle from the low frequency spectrum. The rest of the spectrum still needs to be repaid somehow. How can this result be enhanced? The shout turns out to be the most radical way out.
Roughly speaking, we are talking about a kind of diffuser magnifier. The membrane oscillating on the narrow side of the horn is projected to the wider side. The amplitude with the size of the oscillations will increase proportionally.
Visually, it may seem that the sound coming out of the horn is much more powerful than that emitted by the modest size of the membrane. But the pressure must also be taken into account. A small membrane has a small stroke, but there is a significant resistance of the air compressed by it. So, during the same period, its operation is similar to the efforts of an equivalent large membrane with a significant stroke.
To understand how a horn works, you can study the activity of a speaker in a box directly in the air or on a pipe. It is easy to understand that under the condition of equal “breaths” of the device when using a pipe, the kinetic energy of the displaced air will be higher than in the case of open operation. A similar system - and on "exhalation".
This is due to the fact that almost all the air in the pipe has to acquire the speed of the diffuser. In open space, only the nearest air layers receive it. A little further the speed decreases (elementary geometry). So, acoustic energy is released to the pipe in much larger volumes than into the air.
What happens if, by increasing the length and decreasing the diameter of the pipe, the diffuser of the device remains the same? The air will have to move faster than the diffuser, and on "inhalation" the kinetic energy of the previous air volume will again increase.
There is also a problem: it is unrealistic to get out of the pipe, all the more narrow, to the outside. After all, its open side will reflect back a wave of sound. To prevent this from happening, at the end of the pipe, its diameter must exceed the wavelength. In practice, it should be made as wide as possible. It is logical to give a conical expansion of this part of the device.
However, where the cone is connected in steps to the pipe, the back reflection is still quite large. It is best to connect the cone and pipe into a single whole, expanding weakly at first, and sharply faster in the end. Have you already understood what we are driving at? This is a classic loudspeaker in the form of a horn.

Let's summarize the main idea of the device. The air surrounding it should acquire a maximum of kinetic energy in just one movement. In other words, we want the air to remove the maximum sound energy from the diffuser. For this, the air flowing through a narrow channel is optimal. After all, here he has to move very quickly. But outward the sound should come out of the channel without encountering reverse reflections. To do this, the channel should be steadily expanding closer to the exit.
Curiously, the diffuser located in the horn can be created with an ever smaller diameter, also reducing the amplitude of its oscillations. The speaker's ability to produce low-frequency sounds will remain intact. Ideally, its speaker becomes a powerful electromagnetic coil-magnet system. It moves a small membrane a moderate distance, while creating significant pressure on the air.
The horns even distort the sound specifically. The reason is the nonlinearity of adiabatic air compression. Due to heating during compression, an increase in gas pressure is faster than a decrease in its volume. All sound emitters have this distortion. However, in the case of horns, it is more pronounced due to the significant air compression.
This device does not have the problems of the aforementioned acoustic closure, as well as unnecessary dispersion of sound from behind. After all, the rear part of the diffuser in that case is devoid of a horn and practically does not emit sound. Too small for this, it has a fairly small oscillatory amplitude.
Thanks to the horn, the diffuser transfers its energy to the air. The speaker, both open and in a box, practically cannot do this. Indicators of the transformation of electrical energy supplied to the input into sound:
for a closed box - within one percent;
for a box equipped with a phase inverter - two to three percent;
the horn has thirty to fifty percent.
Agree, the numbers speak for themselves!

1 week ago

you can immediately see the video editing, the waves are around and the person stands rooted to the spot.

2 weeks ago

Strange guy .. very strange

1 month ago

You didn’t understand a hundredth part of the diffusoria, Heeee)) (because you were tired)

1 month ago

Interesting

2 months ago

After Netrebko rolled her eyes ... but the shout went to the ass !!!

4 months ago

Oh, how she sang!

9 months ago

Anchor in * opu 😅😅😅 Ugarnul))) and, by the way, soon there will be 100 thousand of us 👍 keep it up

9 months ago

someday, if it doesn't sink into the depths of YouTube, these videos will be classics!

9 months ago

Shout, OYa. ZYa have already been. Can you make a video about the phase-inverter design of the speaker and why you don't like it?
Thank you in advance.

9 months ago

It became clearer enough than I myself was looking for similar information on the Internet

There are several automotive horn sirens in stock and decided to remake them for warning in front of the house
And now it turned out that at high volume levels, the distortions are huge and put the idea aside

And so interesting

9 months ago

Also tsіkavі your sub "Active savor of that іinshoї speeches, diagrams, etc.

9 months ago

A year ago

Can you clarify one point why, when replacing horn HF drivers, the manufacturer recommends in the service manual to test these drivers at a frequency of 1-3 kHz, although they actually work in the 8-20 kHz band?
Is the test to be carried out using a network (crossover) and with accurate acoustic matching in a pair?

A year ago

Among car audio enthusiasts, there is a point of view that if the efficiency of the speaker is 1%, then all the remaining 99% of the input power is used to warm up the voice coil. I have been explaining for many years that this is not true. That the loudspeaker head is a double-acting serial transducer: electromechanical and mechanoacoustic.
That is, first, electrical energy is converted into mechanical energy. Here, the order of losses is approximately the same as in an electric motor, that is, they are small, up to 10-20%. This is the loss for warming up the voice coil, for overcoming friction forces in the suspension elements, centering washers, etc. But then the mechanical energy of the diffuser movement is converted into acoustic energy, and it is here that the greatest losses in efficiency are due to the low resistance of the medium.
However, not everyone accepts this fact, and the most persistent continue to persist, they say, bullshit, all the power goes to warm up the coil.
Then an experiment was set up, proving that the problem was precisely in the environment. The logic is simple: we take two identical speakers and attach them "face to face" at a very short distance. I had it 0.5 cm between the flanges. It turned out to be such a "push-push" with a connecting layer of air.
We connect one speaker to the output of the amplifier, and the voice coil of the other is simply short-circuited with a small resistance of the ammeter.
If the speaker is a bad electromechanical converter, and almost all the energy goes into heating the coil, then the speaker will give out very weak vibrations to the external environment, and the second will weaken them even more, and the current through the coil of the driven speaker will be scanty compared to the current through the coil the "leading" speaker.
If now a sinusoidal signal is applied to the first speaker, then it will swing the diffuser of the second speaker, and by the current through the ammeter we can judge what order the losses will be after the two speakers convert electrical energy into electrical energy.
So, experience has shown that the current in the voice coil of the slave speaker is not much less than the current in the coil of the master speaker. At different frequencies, the efficiency of this "push-pull" was different, but not 1%, but ten times more, reaching 80% at some frequencies. Up to 80%, Karl!
This clearly indicates that as an electromechanical transducer, the speaker is very efficient, and about 99% of the heat loss in the coil is out of the question.
Anyone can repeat this experience with any woofer. I did this twice: with 8GD-1 and 30GD-2B (75GDN-1-4).
In this video, Alexander explained why the speaker poorly converts electrical energy into acoustic energy. If it gets noticed by the wide masses of "column builders and sub builders" it will be great.