The visit to the Capital had been very fruitful, especially after they met an old friend of Professor Ventura, accidentally, in a component store. Robert, who worked in a large electronic component industry, had a hobby in his spare time, and this hobby had a name, not yet familiar to the Professor and completely unknown to the school principal:
- Home theater? But what is this? - The principal asked.
Robert then invited them to see the biggest news in terms of audio and video (A/V) which he had "implanted" in his "spacious" apartment.
- The idea is to bring to our home, not only the image from the cinema with the use of digital televisions of large screens or even "big screens", but also the sound with a system of many speakers and separation of channels!
The young man was entering the apartment while explaining everything to the Professor and the principal. A "general idea" of the "thing" was what Robert wanted to pass on to both:
- The sound of many recordings is in Dolby Stereo, Dolby Pro-Logic or other modern processes, and the effects are sensational! You must have seen at the cinema the films "Star Wars" or "Dances with Wolves"!
- Yes, they were sensational! - Professor Ventura commented he had seen the films in the Capital. Professor Crick, the principal of the school, did not have the same luck, because the only speaker of the modest cinema in Lemon city did not get more than about 10 watts of the old tube amplifier, and yet with some distortion!
- Well, the tracks of these movies, besides the two normal channels, also have surround channels which surround us in sound with rear and side speakers. In the Pro-logic system we go even further, because we have a central speaker and even a sub-woofer!
- Sub-woofer? - Technical terms were never familiar to the principal. Robert continued:
- Yes, a loud speaker for very serious sounds like explosions, landslides, avalanches, earthquakes...This gives a fantastic realism to the films.
- And you put all this in your apartment? - The Professor had no idea how, but Robert made them enter his "Home Theater". It was a small room in which he had made several adaptations. In one corner the large 42-inch LED TV with two small speakers at the top, two side and a larger central speaker. And, throughout the room, forming the "surround" system, scattered speakers. A three-seat armchair stood in front of the TV, in a strategically determined position.
- I do not have space here for all the speakers I would like to have, because my amplifier has outputs for "only" 11 boxes, but "there is a way".
Robert continued:
- Well, the biggest problem was with the "sub-woofer" that gives the best effects with the bass sounds: I only found a place to install it! Guess where?
The Professor Ventura and the principal looked around the room. Evidently Professor Crick, even if he saw such a "sub-woofer", would not be able to identify it, but Professor Ventura did not see anything either!
- I have no idea! - exclaimed Professor Ventura.
The Home Theater fan explained triumphantly:
- It's under the armchair!
The Principal looked suspiciously at the armchair where he noticed some side openings for the sound, the "porticos." With doubts, he asked:
- Wow! But don’t you have acoustic problems?
- It really has but not acoustics! The 500 watts I apply on it are enough to overcome any resistance! ...
- But then, what kind of problem is there?
- Well, it's hard to watch war movies eating popcorn!
The Professor and the principal wanted to laugh, but they restrained themselves. The guy went on:
- Another problem I noticed was when I brought my 80-year-old aunt to watch the movie "The Earthquake" …
- Yes?
The Professor's and the principal’s eyes stared questioning:
- She lost her teeth!
- Well, if that's all, then there's nothing to worry about!
But there was more! Robert continued:
- Another problem! The other day I brought my friend Tonny, also to watch "The Earthquake"...
- And?...
- The armchair vibrated so much that when the movie ended, he does not know how, but his underwear went to his jacket pocket!
Again the Professor and the principal of the school tried to laugh but could not. What mattered was that, despite the small space, Robert's demonstration was impressive! On his return to Lemon city, Professor Ventura was called by the principal in his room:
- I would like to have a Home Theater at school, because we would have much more realism in the educational films that we rent, besides that we can’t be behind in the news of the electronics! But, here among us, I could also use it in some particular sections.
Professor Ventura agreed with Professor Crick:
- You know, after our return I've been thinking about it, and I even sketched a project! Did you know that our amphitheater could be easily adapted to become, not a "Home Theater", but something intermediate, almost a "Theater", with the sound of a Dolby Stereo or even Pro-Logic cinema and more advanced?
The principal's eyes flashed,
- Truth?
The Professor continued:
- Yes, and we don’t need much! I've been checking our equipment. It will be relatively cheap if we take advantage of the many amplifiers assembled by our students to study! The added power is more than enough for a good effect. We just need a decoder and some additional speakers in the amphitheater!
The principal made a face:
- And what the hell is a decoder? Is it expensive?
- No! This isn’t going to be an issue!
The principal of the technical school scratched his chin and made a request to the Professor:
- Buy what you need, but don’t spend too much!
Leaving the principal’s office, Professor Ventura met Bart and Bert, and even before they greeted him, he ordered: Come with me!
In the lab, Professor Ventura explained everything to the boys who found the idea very interesting:
- Wow! I already imagine the films of George Lucas with the original sound, and here at our school! We no longer need to travel to see the most interesting movies in the big city theaters! - exclaimed Bert enthusiastically.
- It would be a glory! To make all technical schools jealous! - Bart was right.
- But, Professor, is this feasible?
The Professor calmed the two and explained:
- We already have almost all the equipment which basically consists of a big screen, that is to say, a TV projector, a CD-player and good amplifiers besides a decoder for the Home Theater!
- But what does this decoder do? - Bart wanted more information:
- It simply separates the various sound channels, just like an FM stereo decoder, but with a greater number of outputs!
- Wow! It must be expensive! - cried Bert, startled.
- Not really, because we can buy one of the passive type, or even with active circuits which operate with signals of small intensity. - Professor Ventura, gave more explanations. He went on:
- This means that the decoder is the least of our problems as it doesn’t cost too much. Robert gave me the "tips" of how to get one for a good price! As the principal has set a budget, instead of buying all the equipment, we can "invest" more on good bass speakers!
- What?
- Yes, the most interesting effects of the Home Theater occur precisely with the bass, so if we use super-powerful subwoofers we will have something sensational, like realism in explosions, earthquakes, landslides, etc. ...
- Wow! - Bart exclaimed - It will be sensational to have the low frequency vibrations felt "in the bones"! - He did not know, that many people would feel the vibrations "on the skin"!
The Professor then made a sketch on a chalkboard:
- Our amphitheater is small and has wooden floor that was reinforced not too long ago! We can take advantage of our basement to work as a "loudspeaker" and install the bass speakers on the floor! This way, the vibrations will come "from below", as it should with the bass sounds, literally making the "ground tremble" with explosions, landslides, and so on.
- But for that we need a great power! - Bart interrupted.
- Yes, but that's no problem, either!
On the following day, Professor Ventura presented a list of materials to the principal, which was immediately approved! It was much smaller than he'd expected, as it included only the decoder and 6 speakers!
Later, the principal would be surprised, not with the price of the decoder, but with the price of the speakers! No wonder, everyone was frightened when Professor Ventura, Bart and Bert entered the amphitheater, carrying huge "woofers" with more than 1 meter in diameter each! The weight of the "monsters" was concentrated mainly on their magnets with more than 30 kilograms each!
- These woofers we found are really sensational! They respond to less than 20 Hz! I can’t wait to reproduce an earthquake in these "awesomeness"! - Bart was enthusiastic, although he should have said "to produce" instead of reproducing!
- Damn it! They can even reproduce infrasound vibrations! - Bert completed!
In the projection room, six huge 500 watt class D amplifiers with bridged power MOSFETs at each output were installed and powered by the Home Theater decoder's bass output.
For medium and high sounds the smaller speakers that were already part of the amphitheater sound system were kept! The teacher only took care to separate their connections so that they would have Stereo Surround and Stereo Pro-Logic available in the decoder. The signal to excite this powerful system came from the output of the CD player! In total, more than 4 000 watts of sound, being 3000 in the bass range, would fill the small hall!
- Four kilowatts rms or sixteen thousand watts pmpo! Wow, what a sound! exclaimed Bart gloriously as he examined the sonorization plan.
- The "coordinates" of my friend Robert were accurate! The system will look perfect! - Professor Ventura was excited as he made the installations.
At six points on the wooden floor of the amphitheater, circular openings of 1 meter in diameter were made where huge speakers were secured. A strong iron grill with an ingenious system that avoided falling objects and even water penetration when the place would be washed, was placed on top of each speaker!
In a short time, all the connections were made and the first tests performed!
- It's great! it trembles to the "bones"! Great for a "skull dance"! - Bart exclaimed excitedly, still managing to make a joke.
The Professor, on the other hand, agreed with the "positive" signal for Bert in the cockpit to turn off the system.
- Wow! I would like to test with a recording, even on CD, of something more "powerful", such as an earthquake, collapse or whatever!
As it was late, they left it for later! In fact, for the next three days it was not possible to return to the "Home Theater" project, since the tests began and the students' concern was to study, and the Professor’s correct the tests.
Meanwhile, a lot happened!
Mrs. Venus Spendthrift was the wife of the "proboste" and first lady of Lemon city, and as such she was constantly engaged in philanthropic activities. At that moment, for example, she was organizing with the ladies of the local "high society" and some service clubs something to "raise funds" for her social works:
- We've done too many "teas", "dessert evenings" or, ice cream party- We've lost the count! I want something different this time!
Bridget, her faithful friend, and wife of the deputy mayor, agreed:
- It's true, we need to innovate!
It was then that someone in the ladies' group had an idea:
- Let's do a "Jelly Afternoon"!
- "Jelly Afternoon"?
The owner of the idea explained:
- Yes! We are in the fall: neither tea, which is for the winter, nor ice cream, which is for the summer! Let's serve jelly! It's the between! It is easy to do, it costs little, which gives us a good profit for our work!
The mayor's wife cheered! Another lady continued enthusiastically:
- Yes! Strawberry, grape, pineapple, cherry jelly ...
- And lemon from Lemon city! - They could not forget the lemon! The whole economy of the city was based on the endless plantations of this citrus fruit, and therefore it could not be left out!
At this moment Venus made a sad face:
- We have a problem! To make jelly is easy, but where can we have the event if the City Hall is under construction?
Everyone was frustrated at the idea of ??canceling everything, until someone, and this one was, nothing less, but the principal’s wife, Mrs. Linda Crick, provided the alternative solution:
- We can do it at the school's amphitheater! I'm sure my husband will not object because we are now in testing season and it is not being used!
- Yes! Just take out the chairs and we'll have a great hall, almost as big as the City Hall!
- Of course honey! I'll have the chairs taken out and you can use the lounge the day after tomorrow! - said the principal distractedly, who did not even remember the "job" Professor Ventura was doing.
Mrs. Spendthrift handed out the invitations, while the other ladies began making the jelly.
But what most demanded from the ladies in terms of skill and work were not the small jellies formed from inverted shapes, but rather a huge jelly almost one meter in diameter in the form of a half lemon, which would be at the center table of the hall with the glorious flag of Lemon city at its center!
- Be very careful when carrying this! - recommended the first lady, accompanying the four employees "borrowed" from the city who, for the programmed afternoon, carried the enormous gelatin of almost 50 kilos on a round, still shaped table. With extreme caution, because it could not swing, the huge and fluttering dessert was placed on a table in the center of the amphitheater and unmold! In the ample atmosphere of the now-no-seating amphitheater, people still saw the huge dessert flicker just before it stopped!
As it is often the case with this type of event, many people around the ladies of the invited society learned about the "Jelly Afternoon". In addition to the guests of local high society, the only "strangers" to attend were the local newspaper photographers who should register everything for the "social columns".
Needless to say, Professor Ventura, Bart, and Bert were not in the habit of reading the social column of the local newspaper, and so they were not aware that the amphitheater would be "occupied" that day!
The amphitheater was already full of elegant ladies, who tasted the delicious gelatin. The first lady, radiant, served the guests while the director's wife played the role of "cashier" receiving the "contributions”, each flavor had a different price tag for a larger fundraiser.
The photographers had registered the lady next to several personalities, who made a point of displaying the "delicious gelatin" that the "good heart" of the "preboste's wife" had prepared.
All was well, until Bart and Bert, finishing their last test of electronics, "invaded" Professor Ventura's lab with a gleaming CD!
- Look at what we got!
The Professor took the Compact Disc and was also enthusiastic about what he read:
- Original Soundtrack of the Movie "The Earthquake", Dolby Stereo Pro-Logic". Sensational! We can try our system!
The three of them ran towards the amphitheater, not noticing anything unusual, as they entered through the small back door which led directly into the projection room, where all the equipment was, including a brand new CD player.
Not worrying about what was happening in the main hall, the three switched the amplifiers to full power and set the CD to play.
- Before we go there, we have to make adjustments! We have to choose the right spot to see if the equipment is really good! - said the Professor, putting the receiver to his ear.
- Yes! And we need to locate exactly the part of the earthquake! - confirmed Bart while connecting a monitor speaker in the place.
With help from the information on the CD itself, the right spot was located on the first try.
- Let's transfer this sound to the hall! We can’t go there before checking through the instruments if it is reproducing normally! With these powers, any mistake can overload an amplifier! - The Professor said this by pointing to the panel which monitored the outputs of all amplifiers. Ten VU-meters indicated the signal level at the output of each amplifier and therefore the separation of the channels.
It was from this moment that things began to happen in the Jelly Afternoon!
Accompanying the original scene of the film, first a slight tremble began, that one did not know very well where the wave came from. It was the beginning of the "production" and not "reproduction" of the Earthquake! The ladies, entertained with the tasty gelatin, noticed the first weak vibrations, but did not care much.
But the tremble increased and in a short time everything began to really tremble with a terrible sound which penetrated "to the bone" as Bart had said! The "low pitch" effect of the basement from the old building increased the efficiency of the system, producing vibrations of low frequencies that agitated the very structure of the building! Everything was shaking!
Evidently, gelatin and earthquakes didn’t match much and all the jelly began to tremble intensely, more than anything else!
The small portions balanced on the plates in the ladies' hands were the first to suffer the effects of the powerful shockwaves. A fat lady with big breasts and pretty nauseous was the first victim: the two still intact portions of her jellos began to vibrate, but completely "out of phase"! When one "went back" the other "went forth". Despite the fat lady's efforts to keep the "balance" of the thing, after much shaking, the two mouthfuls of jello eventually slipped, falling directly into her huge neckline!
- Oh boy! - was the exclamation of the shamed woman still trying to disguise with a yellow smile.
Other ladies, terrified at the thought of the possibility of everything coming down on them, did not know whether to run or to balance their jellies, and of course, neither possibility became possible in a short time! Accompanying some fainting, the jellies began to fall on their fancy dresses, penetrating necklines and making the floor very slippery! Even those who did not want to run, were unbalanced when stepping on the gelatine spreading and the tumbles began.
But the worst thing happened to the first lady, Mrs. Venus Senpendthrift!
Near the gigantic gelatin, at the center table, she began to feel the effects of the vibration when some portions that were with nearby fell. She slipped and, as she was quite "bulky", leaned against the center table, which could not resist her weight!
The first lady and the "big jello" went to the ground increasing the disaster even more! Initially the flag of Lemon city was just "implanted" and swinging on her head.
The lady's unhappiness in receiving the huge sticky portion did not end there. She fell right over one of the grilles where a speaker was emitting all the low-frequency power vibrations!
Sitting, and full of jello, the fat lady started to vibrate! It seemed like she had "delirium tremens" or according to others who witnessed the scene, who operated a jackhammer! There was also someone who made another type of comparison:
- She looked like one of those concrete shakers! The ones which have the shape of a stick and are used for the concrete to penetrate in a uniform way - said someone later.
But it did not just seem: the effect was the same! The vibrations of the fat lady in conjunction with her advanced "anatomy" made a strange acoustic resonance phenomena. The woman proceeded to behave in a similar way to a "kundt tube" modified with vibrations and beats throughout her body, and this made the gelatine penetrate every possible and imaginable part of her body! To the surprise of all who watched, under Venus' dress, the gelatin was disappearing... Disappearing... Fading... But where? The heavy grille of the speaker underneath was barred!
The mayor's wife's eyes seemed to flutter with the tremor generated by the loudspeaker until, with much effort, she managed to shout
- He... He... He... Helppppppppp...
The ladies who were still with some balance, and less frightened, rushed to raise Mrs Spendthrift, and then the surprise: when she was finally put up with the effort of at least 6 people, her panties had been left on the floor! Full with all the gelatine "absorbed" in the vibrating process! What hardly anyone could explain is how the flag of Brederopolis swayed on top of the clumsy lacy object filled with jello!
The photographer from the opposition newspaper took the time to hit a photo!
That's when the sound stopped!
All this lasted no more than 5 minutes! Professor Ventura, Bart and Bert, satisfied with the tests in the cabin, and without knowing anything of what was happening, programmed the device to reproduce the same sound and went down to the hall - To see the effect!
And when they opened the door that gave access to the amphitheater they really saw the effect "and they almost had a shock!" The exclamation of the three gives an idea of ??the gravity of the scene they witnessed:
- What The F…?
They were still in time to see the fat first lady being helped, the strange lacy cloth filled with gelatin with the flag of Lemon city in the middle of the hall and the general confusion of jello scattered everywhere, ladies being fanned, and so on... They had no doubts: they quickly closed the door to the hall and fled quickly through the back doors, not without turning off the sound equipment!
But, unlike what many readers can imagine, Professor Ventura, Bart and Bert were not "lynched" for it! A solution to restore the well-intentioned ladies' losses, and restore peace in the community was proposed by Professor Theodore Crick in the presence of the mayor and the ladies: the first session at the cinema, presented in the home theater of the school would be paid and the income reverted to the assistance works of the first lady!
- It's ok! - said Mrs Venus Spendthrift, accompanied by the principal's wife - I forgive Professor Ventura!
The chosen film was "Star Wars", and on the opening day, the mayor with some authorities occupied the front lines of the small but now super-sonorized school amphitheater also used for projections from a VCR.
But the surprised Professor, Bart and Bert is that the first session was not a comedy, but from the control room the three could hear public laughter!
- What the hell is happening this time? - The Professor was worried.
Going down to check, the three of them stopped at the door of the hall, and as soon as they understood the reason for the laughter, they laughed as well:
- Oh! Then that's it! Look! - The Professor pointed to the screen:
They could see the shadow of the preboste’s bald head against the light background of the screen, and on the top of it the three only standing strands of hair being the protagonists of a funny "dance" that accompanied the rhythm of the film, provoked by the strong low-frequency sound vibrations.