Saturday, April 18, 2015

Low Stage Part 02 - A case of Lobing

At the very least, matching tweeters mounted on the "A" pillars with mids installed in the kick panels is a terribly risky idea. 
Why, then, is it that so many cars use the technique so successfully? Well, it all depends with what you call successful.
In Low Stage Part 01 - Two Speakers, I tackle some of the myths about fixing perceived stage height. In this second part I will further comment on the challenges resulting from the system's lobing patterns.
Sound judges today, seem to have forgotten that live music is large. Instead, they award higher scores to systems projecting caricature-like images. The more violins seem minuscule in size, the sharper the image these judges think it to be.
image of a mouse playing a miniature bass on top of a car dash
Miniature Instruments
These judges equate small with sharply outlined. But image sharpness comes from transparency rather than size. It is only after removing many layers of veil that we get to see the difference between the suspended instrument and the empty space around it. Closing our eyes while listening to great quality unamplified music demonstrates this. But if asked whether these sound judges routinely listen to real unamplified music, the response is that of an empty stare. Just think about it, even the Boston Pops amplify most of their performances. It is getting harder and harder to listen to the magic that comes from real good musicians playing real good instruments without ElectroVoice ruining the presentation.
I remember going to listen to Sarah Brightman. The beautiful lady captivated me from the moment I first listened to her music. So, when I had a chance, I paid for the tickets. Armed with excitement, I listened attentively. So can you imagine my surprise when her sound was flat and brittle? It was terrible. Whatever the sound engineer was doing, I hoped would end immediately. Surely his acid trip and the loss of high frequency sensitivity made it impossible for him to understand what good sound was. But then again, maybe I was being hypercritical. Then came intermission. As the lights came on, dozens of people around me begun to complain about the terribly bright sound. It seems I was not alone in my conclusion that the sound sucked. How sad indeed.
The bottom line is that when asked about how to earn critical listening skills, I tell people to just listen to real music. It is that good when compared to the garbage we are now exposed to.
When I audition a system, I pay lots of attention to the size of the instruments. Properly aligning speakers will inevitably result in larger, deeper images. It is this quest that makes me conclude that most systems with speakers on the "A" pillars fail the time domain test. While placing  speakers like tweeters up high helps with the perceived image height, it does nothing to create realistically sized instruments. Have you ever listened to a grand piano. The sound is as large as a room. But most car audio systems, even the better ones, shrink instrument dimensions in the pursuit of so called image definition as they define it.
On the other hand, a system using properly time corrected speakers will do both, large instrument size and solid image height. It is interesting to note that the time correction I am referring to is independent of speaker positioning. In other words, I am not against speakers on the "A" pillars. I am against using them as a way to patch fundamental problems without properly addressing such issues directly. Most system designers path their height issues and completely miss the fact that inadequate time response has killed any hope at realistic image dimensions. Soon a self fulfilling prophesy is created where judges begin to reward poor performance with higher scores because of herd behavior.
At a recent Consumer Electronics Show, I spent time with my friends Chris and Melissa Owen at their high end room. Orca had lent them speakers sporting their latest design. To be clear, the speakers looked fantastically finished. Moreover, these deployed really good drivers from Orca's arsenal. But as soon as Chris fired up the system for me, I told him that the crossover had problems that were creating comb-filtering. It seems as if the designer, like many others within the industry, used 12dB/oct parallel crossovers between drivers mounted on a surface that stood perpendicular to the floor. Anyone who pays attention to this stuff would know that this was trouble waiting to happen. But for the many who think that amplitude linearity is all that matters, the speakers were fine, just as their LEAP modeling software had predicted. So, as we move onto the car, consider that the problems I will address are also ubiquitous in home speakers. Again, it's a bit of a herd problem.
I recently showed a dear friend what happens when a tweeter on the "A" pillars is matched with midrange speakers in the kick panels. I used modeling software that is freely distributed. Oh, how I wish I had these tools when I started in the industry. Back then I had to interpret all the multidimensional variables while trying to make sense of what I was listening. I used no equipment when designing passive crossovers; just my trusted ears.
Polar response for tweeters in "A" pillars and mids in kick panels
 Take a look at the illustration above. It models what the polar response would be for a system with a tweeter mounted on the "A"pillars while the mids are in the kick panels. The crossover uses a 12dB/oct sloped at a frequency of 3.5KHz. Note that both of these settings are quite common in the industry. As it should be immediately evident, destructive interference would make it very difficult to find a listening position where spectral performance could be maximized. Just move your head an inch or so and all dimensional sense will evaporate. This kind of lobing error seems to correlate with poor vertical spread or instrument size; no matter whether in a car or a home system. In fact, one is often surprised of how many so called high end speakers display poor polar response. For many of them, tilting the speaker backwards would solve the issues. This explains why there are so many speaker platform designers that facilitate just such tilt without risking that the speakers fall backwards. It is an expensive way to correct what could otherwise be handled at the design stage. Unfortunately, the problems depicted here are much more gruesome. No amount of tilt will fix them. Either the distance between the drivers needs to be reduced or the crossover point should come down in frequency by quite a bit.
Polar response for tweeter and mid in kick panels
Now look at the second illustration for what happens when both drivers are located side by side to each other in the kick panel. Crossover frequency and slope remain the same. The only aspect worth noting is that to fix the problems associated with the 12dB/Oct design the tweeter has to be physically located on a plane behind that of the mid. This helps til the lobe upwards to ensure that maximum spacial performance occurs anywhere a common listener would place her head.
And if in need of further clarification, the second set up would also project images at eye level. The main difference is that images from the latter setup would be much larger, just as God intended.
Polar Response at 10KHz between
tweeters in the "A" pillars and kick panels
Again, I am not saying that height is wrong when using tweeters on the "A" pillars. I am simply clarifying that by themselves, they are no solution. The same attention to detail needed for properly setting up speakers in the kick panels will be needed with speakers mounted above the dash. Furthermore, to prevent the negative effects from comb-filtering, a less common slope should be matched with a lower crossover point aside from proper time adjustments.
And while we are on the subject, what do you think happens wen people use both drivers in the kick panels and then add a second set of tweeters on the "A" pillars to "lift" the sound. Often, well intended attempts use a higher frequency high pass filter for the tweeters mounted above the dash. Well, chaos is what happens. Look at the illustration to the left. It represents what happens at 10KHz with a 6dB/Oct highpass slope for a tweeter mounted on the "A" pillar and matched to a tweeter in the kick panel. It begs the question of how in the hell would one expect reliable performance; forget about good sound, just getting the same sound all the time would be a bonus.
Can anyone hear the difference? Yes. Can anyone know what's wrong with the music? No, In simple terms, the change is visceral. We just know it's wrong. These types of problems tend to fatigue us quickly.
Are the issues discussed correctable? Yes, but only when the constraints are understood. Unfortunately, many industry designers miss the science side of sound and attempt to solve everything as if it was all an art. While music is certainly an art, we should not waste valuable creative time on things better left to our tools. I hope you found this post as helpful.

Friday, April 17, 2015

Reflected Sound as the Cause of All Car-Audio Evil

illustration of direct and reflected waves between a speaker and a listener
Is Reflected Sound Evil?
Some argue that reflected sound is utterly undesirable within the car. They use this to support their thesis that speakers on "A" pillars are the only way to reproduce good sound. 
In my Low Stage Part 01 - Two Speakers post I addressed the issue of perceived height. I directly targeted the argument often made that real acoustic performance is only possible by using speakers mounted on the "A" pillars. Well, recently, it seems that the autosound competition circuit has been getting further addicted to the same Kool-Aid. This time, though, I would like to address the argument that speakers on the "A" pillars are superior because of their ability to deliver direct sound and that all other installation methods will fail due to their reflected sound character.
Unfortunately, the optimistic souls that make such argument miss centuries of empirical historic evidence and thousands of modern sound reproduction methods that would negate their argument.
To start, a vehicle is such a small enclosure that it would be a stretch to think that the reflected sound of even those speakers mounted on "A" pillars lack a substantial amount of reflected sound. Whether from the immediate surrounding boundaries like the windshield or windows, the signature sound of any car is very different from that of even small home rooms because of the large amplitude of the reflected energy present within vehicles. I remember auditioning a vehicle with pods for a set of Dynaudio tweeter and mid built onto the "A" pillars. The amount of energy that coupled to the surface of the near-side window was so large that getting anything to image was everything but impossible. And that says nothing about the poor tonal color created by the coupling. Perfectly great drivers were made mediocre. I happen to know Dynaudios very well and knew immediately something was very wrong. In essence, the windshield pods' response was heavily influenced by their reflected energy, which is what creates the coupling I mentioned.
Black and White Picture of French Horn musicians
French Horns mostly do reflected sound
Then there is the issue that reflected sound is much more common that it gets credit for by detractors. For example, next time you go to listen to your local symphonic orchestra, pay attention to French Horns. French Horns are routinely played towards the back of the stage. Therefore, it is their reflected sound that we listen to when we audition any of the great orchestral works that we love so much.
It should therefore be noted that I have yet to hear complains from any professional musician about the quality of the sound of rear firing French Horns. Besides, I doubt anyone in car audio would claim to have better hearing than those who receive great incomes as compensation for their more than ten thousand hours of commitment to playing music. In fact, if such was the case and reflected sound was clearly objectionable, more than one of the many liberal orchestra conductors out there would have made immediate changes. But as it turns out, French Horns have a nice and pleasant characteristic sound. Could it be that their reflected energy is pleasing rather than objectionable?
Don't take me wrong, I have nothing against direct sound. My home speakers, which I designed presumably in a way I endorse, use direct sound as the core of their design. It is just that I also don't have anything against reflected sound either. In fact, I am comfortable with both. No threats to my self confidence here. Whether the direct sound is dominant or not, I am happy with whatever it is, so long as it sounds great.
Yes, I know that someone could argue that they can easily tell that French Horns are reflecting their acoustic energy. After all, they sound larger than they should, based strictly on their physical size. When reflected, sound waves seem to emanate from an array rather than a single point. In other words, their wave front is more parallel than concentric. But the same thing happens when waves originate from sources located afar. If it were not for the loss of energy as the wave travels, these long distance sources would present a parallel wave front. Moreover, aren't arrays used in plenty of direct sound applications? So what would the difference be between a reflected wave that now looks like that from an array and an actual wave resulting from an array?
In any case, outside of describing sound as seeming larger, it would be very difficult for someone to argue that their physiology has made them capable of differentiating between a concentric wave front and a parallel one. Let's remember that all circles are made up from tangential lines. If in doubt, check your Calculus books for a refresher.
Picture of a trumpet playerNow let's go back in time to Dallas, Texas. Some time ago, James Feltenberger, the fabulous Dallas Symphony trumpeter, gave me the honor of listening to his fantastic trumpets played a few inches from my face. At the time, I anticipated getting my ears ripped off. After all James has quite the lungs and trumpets are often regarded as bright instruments. But to my surprise, I never reached anywhere near the threshold of pain. On the contrary, the sound was sweet and full-bodied.
What? Am I implying that trumpets are not bright? And what body am I talking about? Don't trumpets just have a thin metal pipe bent a few times? Well, yes and yes. Trumpets, at least when played by real musicians like James, are warm despite lacking a large wooden resonator like those from Violins or Cellos. It was clear that the direct energy coming from the front of the trumpet was far from being the only defining factor of the resulting sound. The rest of the metallic pipeline energized the room just as much, but in an omni-directional fashion.
Picture of MBL's 101 X-treme omnidirectional speaker
MBL 101 Omnidirectional Speaker
So how is it that most sound systems don't reproduce trumpets as I am describing? Well, the answer may be that those systems are simply not transparent enough. But if in doubt, I can undeniably certify that James was not hiding any cheese-ball Bose speakers anywhere in the room as he played music for me. Sorry for offending cheese-balls. I digressed.
So, we have looked at the fact that professional musicians use reflected sound without much fuzz. We also explored how even small-body instruments like trumpets strongly energize space in an omni-directional fashion rather than a just a direct one. This explains why there is a large number of uber expensive home speakers that sport omni-directionality as their main feature. Enter the German made MBL 101. I am sure that more than one car guy missed this engineering beauty. And then there are plasma speakers which, besides being omni-directional, are also quite rare.
It is now time to look at the venue. There are generally two types of orchestral theaters: large and small. Their size generally depends on the era when they were built. Most small theaters were built after the middle ages. Since Baroque groups were made up from a few players and lacked percussion or grand pianos, there was a need for theaters that would amplify their music. So, the horse-shoe shaped theater was born.
Later as more and more Opera was enjoyed through out the old continent, these small horse shoe theaters served well to those attempting to transfer a broad range of the musical notes emanating from their mouth. It is generally accepted that these theaters project a beautiful sound. Whether talking about the European originals or their more modern copies built in say, Guanajuato, Mexico, I can attest to their great warm sound.
picture of Miss Van Der Rohe's Barcelona pavilion
Mies Van Der Rohe's Barcelona Pavilion
Then orchestras begun to get massive. 19th century composers started to pump up the dynamic range while blasting the sound to 10. To accomplish this, they needed lots of violins and flutes. They also added quite a bit of percussion and big Pianos. So, theaters had to get bigger. And since architecture had also changed, theaters where no longer built as horse-shoes with balconies heavily decorated in golden stuff; a la Donald Trump.
Instead, do you remember Mies Van Der Rohe's Barcelona pavilion and the whole Bauhaus architectural style? Big open spaces, large concrete surfaces and lots of metal created the look that has influenced most modern music halls since.
Inside picture of the Royal Festival Hall in London
Royal Festival Hall, London, UK
While in England, I spent quite a bit of time doing critical listening as a wondering member of the audience at the Royal Festival Hall in London. Let me tell you, the warmth of the old theaters disappears as soon as yo step into one of these newer beasts. But by no means does it mean that the new sound houses are bad; many are fantastic. The good ones sound very open and fast. They are simply not as warm as Baroque venues.
The main difference comes from the fact that in post medieval theaters direct sound takes a second seat to reflected sound (pun intended).
While warmth happens within modern theaters for listeners located at the very back of the balcony section, old theater magic happens for all listeners. Baroque theaters seem to use the whole theater in a similar fashion to how a guitar uses its resonant box. The sound is amplified and its color changes. I think that it is almost impossible, without any comparative reference, to judge exactly how much of the resulting sound comes from reflected energy and how much from direct sound.

Sample 1:
Chart of Impulse response with predominant direct energy video

Sample 2:
Chart of Impulse response with predominant reflected energy video

Listen to these two sound samples here. They were captured by recording a gunshot inside the San Carlo Opera House in Naples, Italy, at two different seats. For sample one, the microphone was positioned a few feet from the stage. For the second sample, the microphone was positioned inside the most prestigious of locations within this very well loved Opera hall: the royal box. The theater is known for its incredibly sweet acoustics. Plenty of Operas have been enjoyed by audiences for centuries.
Without listening to sample one, would you be able to certify whether the dominant energy is direct or reflected? Look at the charts. Reflected energy is, as a matter of fact, what dominates the impulse graph.
Only after directly comparing both samples would most audiences note the difference in decay and distribution in energy. This means that without any preconceptions or the ability to change seats, royal guests would have experienced a much richer and musically engaging acoustic presentation that left nothing to complain about.
Evidence corroborates this statement. For centuries, no one has complained about the lack of direct sound present in these acoustic venues. Which means that either direct sound is not all that it is claimed to be or that millions of people who listened to real music, in ways we only read about today, were wrong. After all, what would they know, right? Without modern MP3 players they surely missed the best sound possible, right? ... Not.
Picture of Veritas Waveguide
Veritas Waveguide
To finalize, I will call on the obvious. For those in the car audio industry, do any of you remember Waveguides? Well, with the exception of the Illusion ones, all other were purveyors of more than 99% reflected sound at the very least. From the moment that the dome energizes the compression slits within the motor, to the time when sound waves crash onto the elbow walls inside the throat area, there is just nothing direct about their sound. Yet, tens of thousands of waveguides were sold without resulting on any reflected sound complains. As for the performance outcomes, there were at least hundreds if not thousands of installations achieving great sound.
Again, I have nothing against direct sound. It is just that within the car environment, where reflected sound is so dominant, I argue that great results could be achieved by dampening direct sound and letting reflected sound do its magic unobstructed. In a way, that is exactly what the designers of compression drivers attempted to do. It is also a technique I have used in enough circumstances as to trust it to be a viable alternative in the quest for best sound. Moreover, I am not the only one. Chris Owen was in fact the person who introduced me to this technique. Then there was Dick Olsher from Stereophile Magazine who at a Consumer Electronics Show demonstrated speakers that fired backwards rather than directly at the audience.
Here, I would like to remind all experts of what the later Richard Feynman would say "Science is the belief in the ignorance of experts". In other words, to be real scientists, let's not fear changing our minds just because of preconceptions. If a new scientific test results in a new theory you happen to disagree with, just as Einstein distrusted Quantum mechanics, the problem may be within you and not withing the test; again just as history placed Einstein on the wrong side of the particle theory debate.
illustration of Thomas Young's Double Slit Test
Double Slit Electron Experiment
Talking about Quantum theory, let's wrap this up. It all comes down to the fact that we are listening to waves and not particles. To see what this means, read about the Thomas Young's Double Slit Electron Experiment that so baffled physicists about a century ago. When electrons (particles) pass through double slot openings, the expected particle behavior fails. Instead, they behave as waves; perhaps because they are energy fields, if you take the position of string theorists. In any case, this Quantum Physics experiment shows the difference between particles and waves; a difference that many audio experts seem to completely miss. In their minds, sound wave behave as particles. Yes, it's crazy...

Sunday, April 5, 2015

BAJELE AL BOOM - Car Audio & Electronics Magazine en Español

Picture of Alberto A Lopez and his award winning Sentra
In 1992, Car Audio Magazine launched its first Spanish edition. Coincidentally, my car was featured in it. Years later, when I worked in Mexico as a consultant, retailers were eager to show me the magazine. So one could safely conclude that the Spanish version was better received than those in the US would have thought. This leaves us with the question of why the translation services did not continue.
Perhaps one reason was that the translation was generally substandard. This comes from the fact that translation services often lack the insight needed to convey conversations fluidly withing highly technical industries like this one.
Whatever the reason, I remain ecstatic to have been so lucky. So, let me share the transcript of the Spanish version of the article originally written by Edwige Grimes and photographed by Bobbi Lane:

Composite image of Alberto A Lopez Sentra's trunk with and without stealth covers
Construyendo un piso falso y los paneles para el sonido (abajo),
López mantuvo la mayoría del espacio en el portaequipaje (arriba).
El instalador Alberto López aprendió que sonidos fuertes no significan mejor.

Alberto López fue expuesto por primera vez a car audio de alto nivel en pruebas de sonido en Texas en el año de 186. Inmediatamente, encontró un nuevo hobby. "Yo nunca había visto algo como esto," dice el instalador, de 25 años de edad, de Inphase Car Audio en Omaha, Nebraska. 
Alberto admite, "en Mexico no tenemos nada como esto. Yo quede impresionado. Por supuesto lo que me atrajo al principio fueron los carros boom."
Loopez aprendio rapidamente que los sonidos fuertes no son siempre lo mejor. El primer sistema de sonido en su Sentra de 1989 fue disenado primeramente para cantidad de sonido. 
Alberto dice, "pero usted se cansa de sonidos fuertes." "Mis oídos me dolieron en una ocasión, y después en otra ocasión, entonces yo empecé a preocuparme acerca de la situación."
Compitiendo en pruebas de sonido lo apuraron a modificar el sistema de sonido. Alberto dice "yo empecé a aprender más y empecé a ser menos y menos ruidoso. Ya no es cosa de ruido fuerte para nada."
López es estudiante de negocios en la Universidad de Nebraska en Omaha. El aprendió instalaciones y diseño de sistemas ablando con la gente que el pudiera, e inspeccionando vehículos en competencias de sonido. Los conocimientos de física y arquitectura de sus estudios universitarios en su nativo México también son una gran ayuda.

picture of the door in Alberto A Lopez's competition Sentra
López reconstruyo los paneles de las puertas cubriéndolas con un paño
de lana y un vinilo gris. Cada puerta tiene un woofer de 8 pulgadas.
Empezando Sin Nada
La conquista de López para mejorar la calidad de sonido empezó con la modificación de las bocinas de acuerdo con sus necesidades. 
Cada puerta tiene los woofers Morel MW-224 8 pulgadas. López trato el cono de los woofers cubriéndolos con cerámica para alterar el sonido. El explica "el peso del cono es diferente y toda la proporción de las bocinas es diferente."
López reconstruyo completamente los paneles de la puerta, cubiertas en paño de lana y vinilo gris que hacen juego con el interior de cuero del Sentra, rejas metálicas para las bocinas cubiertas con una tela transparente sobre el woofer para su protección. 
picture of rear deck in Alberto A Lopez's competition Sentra
Las redes pasivas de crossover para las bocinas
en las puertas fueron montadas en la cubierta de
atrás (abajo) y cubiertas con rejas (arriba).
De acuerdo a López agregando redes crossover hechos a la medida también ayudo a mejorar el sonido de los woofers. "El woofer era muy bueno con las voces, pero era un poco débil en el medio bajo y [las redes] lo convirtieron en un sonido suave, y picante - bueno para el medio bajo con suaves ondas saliendo a medio alcance."
López construyo la red de crossover por su propia cuenta y los monto en la cubierta de atrás. Primero el corto orificios en la cubierta lo suficientemente grandes para las redes. Después, él diseñó un panel de tabla de madera que encajan debajo de la cubierta y refuerzan la fibra de vidrio. Entonces el monto las redes al panel y las cubrió con las verjas de las bocinas que hacen juego con las verjas de las bocinas en las puertas. Como toque final, la cubierta de atrás fue forrada con el mismo material que se uso para los paneles de las puertas. 

Bocinas en el Piso
López decidió experimentar con bocinas montadas al nivel de los pies en su vehículo. El dice, "yo sabía del concepto, pero yo no sabía porque trabajaba o como trabajaba."
picture of the kick panels in Alberto A Lopez's competition Sentra
Caparazón construido a la medida para
cada panel contiene un tweeter de 4
pulgadas, medio alcance y 0.75 pulgadas.
Los tweeters, Cabasse MD-100 4 pulgadas medio alcance y DOM-4 .075 en bocinas hechos a la medida con caparazón unidos al panel del piso. La parte de atrás de cada caparazón y el panel del piso detrás de este, fueron cortados para acomodar el magneto grande del tweeter, que López comparo al el magneto de la bocina de 5.25 pulgadas. El remarca "Esto es algo masivo."
Las bocinas del bafle fueron pintadas con pintura FleckStone gris, y los caparazones fueron cubiertos con vinilo. Verjas como en las bocinas de las puertas con tela sobre el caparazón para proteger los conos de las bocinas. 
Yo empecé a experimentar con sonido allá," dice López refiriéndose a las bocinas en el panel del piso, además el trato diferentes ángulos y crossover de redes hasta que encontró la combinación que funcionó. 
picture of chair mounted passive crossovers in Alberto A Lopez's competition Sentra
Un lugar no muy común para poner
los crossover pasivos. Bolsas pequeñas
con cremalleras en las sillas contienen
redes pasivas crossover para los
paneles de las bocinas en el piso.
Las redes pasivas de crossover a la medida para las bocinas en los paneles del piso están localizadas en una caja de madera instalada dentro de las sillas de adelante. La mayoría de la espuma en el interior y las varillas de soporte fueron removidas para instalar los crossovers, explico López. 
"Esta en su espalada, pero no los puede sentir," el dijo, explicando que los crossovers fueron montados en varillas flexibles dentro de las sillas. "Los crossover están suspendidos de tal manera que cuando uno se sienta, usted los empuja de una manera que giran de allá para acá." Cubiertas de plexiglas protegen las redes, que se encuentran escondidas de bajo de una pequena bolsa con cremallera cocida en la parte de atrás de las sillas. 
Cada panel tiene en la parte de atrás un woofer Peerless P-228 de 8 pulgadas montado dentro de un paquete de fibra de vidrio hecho a la medida. Los paneles que esconden estas bocinas no se pueden remover. 

picture of aperiodic subwoofer box in Alberto A Lopez's competition Sentra
Caja que se puede ver através debajo de la cubierta de atrás
contiene dos subwoofers Dunaudio de 12 pulgadas.
Esquema del Portaequipaje
López diseñó el esquema de los componentes en el portaequipaje con conservación de espacio y utilidad en la mente. El indica, "mi portaequipaje tiene mas o menos un 90% de espacio para cargo."
El empezó construyendo y diseñando un empaque para subwoofer que encajara debajo de la cubierta de atrás. El empaque, construido de tabla de madera de 15 pulgadas, tiene dos subwoofers Dynaudio 30W100 de 12 pulgadas. El lado del empaque mirando hacia el portaequipaje fue encajado con una ventana visible de plexiglas. Puertos de membrana en los lados permiten que el woofer "respire" de acuerdo a López. También, la superficie interior del empaque fue forrada en cuero con el mismo material que se uso para el interior.

picture of amp rack in Alberto A Lopez's competition Sentra
Piso falso en el portaequipaje tiene
amplificador, equalizador y bloque de fusibles.
El panel e la pared derecha del portaequipaje
tiene una caja para los capacitores.
Paneles de Portaequipaje Pintados
Se fabrico un piso falso de residuos de madera que encaja sobre el piso original del portaequipaje. Fue cubierto con el mismo material de paño de lana de interior. 
Dos amplificadores HiFonics Ulises están enterrados en el centro del piso falso, a cada lado. Arriba de ellos hay un equalizador Alesis MEQ-230 montado al mismo nivel del piso falso, y arriba del EQ hay una batería US Amps y fusible en bloque Sound Quest. Una pieza de plexiglass removible protege los componentes, y una alfombra cubre todo el piso. 
Un panel en la pared izquierda retiene un Audio Control Epicenter que fue pintado para que hiciera juego con el carro. "No salió tan bien como yo quería, pero está bastante similar," admitió López. También en este panel hay varios interruptores que controlan los aspectos del sistema. 
picture of custom epicenter in Alberto A Lopez's competition Sentra
La pared izquierda del
portaequipaje tiene el Epicenter
pintado a mano e interruptores.
Un panel similar en la pared derecha retiene capacitores Autosound 2000 Stiffening. López dice acerca de los capacitores "Me gusta cómo trabajan, refiriéndome al sonido." Para la protección de los dos paneles tiene una cubierta removible de plexiglass. López afirma "todos los bordes están pulidos incluso los pequeños orificios." Como toque final los paneles que cubren con el paño de lana encajan sobre el plexiglass.
López puso sus capacidades de pintor en el diagrama del sistema de sonido y la red de crossover en la cubierta del portaequipaje. Pequeños LED controlados con interruptores en la pared izquierda iluminan los diagramas. 
La cubierta motorizada del portaequipaje es controlada por el sistema de seguridad Clifford 600 con transmisor a control remoto. López escondió los activadores grandes construyendo unos paneles a su alrededor montados debajo de las bisagras del portaequipaje.

picture of Denon head unit in Alberto A Lopez's competition Sentra
No estos no son de fabrica. López hizo al
radio CD Denon parecer "Nissan."
El Sonido es lo Importante
Échele un vistazo a la unidad principal en el panel delantero, y usted creerá que Nissan a empezado a instalar equipos de sonido CD en todos los Sentras. Pero la etiqueta "Nissan" en la cubierta es solamente para cubrir lo que hay en realidad: un radio Cd convertido de pullout (empuje hacia fuera) en una montura permanente.
López dice "en casi todos los shows a los que voy los jueces me preguntan si ese es el radio que quiero usar." "Los jueces creen que es de la fabrica." Una pieza negra de plástico ABC retiene la unidad principal resaltando en el panel delantero. 
Varios botones fueron integrados en la consola del centro cerca del freno de mano para controlar las funciones del radio haciendo las operaciones mas fáciles y seguras. Los controles instalados de las ventanas también se encuentran en este lugar.
illustration of system diagram in Alberto A Lopez's competition Sentra
Diagrama del sistema.
Para mejorar el sistema eléctrico debajo del cofre delantero, López primero reemplazo la batería de fabrica por una más grande para complementar la batería U.S. Amps en el portaequipaje. Un insolador Sound Quest de 120 amperios separa las dos baterías. El alternador de fabrica fue reemplazado con un modelo de 120 amperios de Wrangler. 
López algunas veces se lamenta de que su hobby y profesión frecuentemente lo dejan corto de dinero, pero el dice que vale la pena. 
López dice "¿Sabe usted que es lo que yo disfruto más? El sonido." "Todas las dificultades por las que paso, todas las instalaciones, pero el sonido, eso es lo mas importante."

Image of Cover of Car Audio & Electronics Magazine Special Edition in Spanish
Car Audio & Electronics Magazine
Special Edition in Spanish
Image of Index of Car Audio & Electronics Magazine Special Edition in Spanish
Car Audio & Electronics Magazine
Special Edition in Spanish

Image of Bajale al Boom Article - pages 48 and 49 - Car Audio & Electronics Magazine Special Edition in Spanish
Bajale al Boom Article
Pages 48 and 49
Car Audio & Electronics Magazine
Special Edition in Spanish

Image of Bajale al Boom Article - page 50 - Car Audio & Electronics Magazine Special Edition in Spanish
Image of Bajale al Boom Article
Page 50
Car Audio & Electronics Magazine
Special Edition in Spanish
Image of Bajale al Boom Article - page 52 - Car Audio & Electronics Magazine Special Edition in Spanish
Bajale al Boom Article
Page 52
Car Audio & Electronics Magazine
Special Edition in Spanish

Image of Bajale al Boom Article - page 54 - Car Audio & Electronics Magazine Special Edition in Spanish
Bajale al Boom Article
Page 54
Car Audio & Electronics Magazine
Special Edition in Spanish

Also, make sure to check the previous post on this vehicle:
What would you do after failing to build your small business ? I stood up and got to work.

Saturday, April 4, 2015

Car Stereo & Security No. 52 - Son of Seismic II

In October of 1996, British news stands offered issue number 52 of Car Stereo & Security magazine with the first article on Car Audio Product's van.
Pictures of Paul Richardson, Alberto Lopez and Nathan Pearce
If you're wondering why normally sane
people would look like this, try polishing
Perspex until 4am, and you'll find out!
Paul, the team and I had not even finished the installation when these the first shots were taken.
Despite the fact that market expectation was great, no one outside of our shop had any idea of what the van would have. Everyone in the circuit expected a bass car. So when the word went out that we had cut holes in the floor, speculation of a rule-breaking port to the outside spread quickly. But as everybody found later, the only thing blowing air to the exterior of this award winning vehicle was the incredibly powerful cooling system that kept the amps in the motorized racks from getting toasty.
The following is the transcript of the article. Enjoy!

front picture of the best sounding van in the worldUnfortunately I well remember the demise of 'Seismic' - the first demonstration van in the UK. It was on the way back to the importers' offices in London from a Sound-Off in Torquay when it suffered a serious engine fire. How serious? Serious enough to destroy the interior and audio installation completely. There was much mourning and deep depression in the land.

Then came 'Son of Seismic' and an all-new van. But by the end of the 1995 season, the guys at Car Audio Products felt that even more could be achieved. So a new installation was devised, and this time the aim was to produce a system that could compete in both SPL and Point of Reference classes at expert level. The intention was also for the van to make a trip to the US to compete with the best the States has to offer. Bring on the 'Son of Seismic II'.

Complete shot of the SPL system inside of the best sounding van in the world.
It requires hours and hours of work to make the edge of a piece
of plexi catch the light like this. When the POR system
is in use, there's a set of solid grilles to cover this lot.
Before we get into the meat-and-two-veg of the feature, I ought to point out that the system isn't totally finished. But even so, there's so much to talk about that I could fill the whole magazine with what's been done. And before we go any further, let me point out one thing - if you think that this is just a revamp of the system used last year, you just couldn't be further from the truth. Every component, cable and panel was removed from the vehicle before work commenced on the current project seven months ago, Since then, a total of 6,500 man-hours has gone into it. In all, seven people have been working on the system although the three main stalwarts are Pail Richardson, who is responsible for the design of the SPL side of the system; Alberto Lopez, designer of the POR side; and Nathan Pearce helping out with the actual physical cutting, shaping, fitting and wiring. And believe me, there is enough cable in the thing to wire an old-style telephone exchange. 

Three Into One
close up of the speaker grills used in the best sounding van in the world.
The back of the grilles just
have to be seen to be believed.
The installation in 'SoS II' is actually two completely separate systems, with only the head unit as a common component. One is essentially for sound quality and the other for SPL and demonstration purposes, although there are actually some differences between what's used for the latter two. I really can't go through a list of the products used since there wouldn't be any space left to tell you about some of the more intricate parts of the installation. In total there are 46 speakers (16 of these being 15in woofersused for the SPL system); 18 Earthquake 1000BX amplifiers, including two which have been modified to run in pure class A at 30W per channel; two 240A alternators; 18 batteries; three signal processors and two head units. I'm sure you appreciate why I'm not going to go into how the whole lot is connected...

photo of the interior speaker locations of the best sounding van in the world
The rather strange positioning of the
Eton drivers is not for looks; the system
has been fired up with the amps outside the
vehicle and is said to "image like a charm".
Although we can't show you a picture of all the head-unit installation because it wasn't quite there at the time of my visit, let me assure you that it's definitely something speacial. In fact, you won't actually be able to see a head unit at all. The display has been custom-made and will go behind a smoked plexi panel in the top of the centre of the completely custom-built dash. Yes, that's correct - there is nothing of the original dashboard left in the vehicle. the one that's there has been built from scratch from 1in MDF which is filled, sanded and trimmed to perfection. Getting back to the head-unit, the display is in the dash but the main player is in the bottom of the centre console - the discs are inserted via a small slot in the driver's side. A custom-made set of controls has been manufactured and built into a stylish armrest in between the seats, giving superb ergonomic experience from the driver's chair. 


For the demo part of the
system, Paul reckoned
they needed a bit more Hf
than the Eton tweeters had
to offer. So there are five
more in each kick panel.
For real SPL frenzies, you wouldn't actually want to be inside. After all, the old system in the van recorded a score of over 150 at events last year, and the new system i sure to improve on that. So, they're in the process of building a console that'll plug into the van, making the system fully controllable from outside. Talking of control, to ensure that the system has enough power on tap, the regulators for the alternators (capable of producing 500A between them) can sense the voltage of the supply to the audio system or the van's own electrical system depending on what it's required. The actual voltage at which the regulators operate can also be adjusted.

close up picture of the head unit's control panel inside the best sounding van in the world
The custom-made control panel for the
head-unit is located in the centre arm rest.
All the power form the two alternators runs to the rear of the vehicle (where the amp racks are) via a pair of 1/0 gauge cables and of course the earthing for the engine has been uprated to a similar dimension. Each amplifier has its own battery and each woofer has its own amplifier, connected with 8AWG cable. The signal for the woofer array also passes through a USD pro equaliser and is time-aligned before it gets to the amplifiers. As with all the clear acrylic panels used in the van - and there is an awful lot of them - all of the edges of the baffles between the woofers  have been polished by hand to an incredible finish. The hours required to do this really can't be justified but it's superb to see.

Sound Quality

close up photo of the ETON mids installed in the floor of the best sounding van in the world
The sound quality or point of reference system uses the head-unit that's been grafted into the vehicle. The output from the unit can be switched one of two ways - either directly into the two previously mentioned modified Earthquake 1000 BX amplifiers for the listening part of a Sound Off competition or via a pair of USD equalisers for the RTA section. As well as being modified to run in Class A, there are other changes to the amplifiers. Once the correct input gain levels were found, the pots were removed and replaced with fixed-value resisters and all the bass EQ and crossover facilities were removed. It's not the head-unit volume control which i actually used to select the listening levelof the system but a set of high-quality motorised pots placed just before the amplifier in the signal path.

picture of the engine compartment of the best sounding van in the world
Photographing plexi is never an easy task, but I'm sure you
can see the perfection of this piece. Beneath it are the two fuses
for main power cables and the two alternator regulators.
oh - they've even used Zeus fasteners - like with F1
bodywork - to make changing a fuse a quick job.
The sound-quality system uses a completely different speaker array from the SPL side. All the speakers (two 8in woofers two 51/4in mids and a pair of 3/4in tweeters) are from the German ETON company, ho manufactures raw drive units for domestic loudspeakers, although there has been some modification of the units to suit this application - such as increasing the cone mass of the woofers.

photo of the battery rack of the best sounding van in the world
The bus-bars connecting the 16 batteries - one for
each sub amplifier - take a hell of a lot of polishing.
There's even a stiffening cap for each amplifier as well.
As for the apeaker positioning, this is quite radical although I have been reassured by Alberto that it's a proven method of placement. Both the mids and tweeters are mounted into the floor of the vehicle. The mids are mounted into the best piece of plexi shaping that I've seen in a car in the UK. The material was shaped over a die so that an angle mounting for the speaker was formed. This was then machined to within 0.015in so that the speaker would seal perfectly when installed. All the speaker fixings into the plexi are via Allen bolts and proper captive fixings so that a good tight joint can be formed without causing cracks in the acrylic. Behind these drivers is a small enclosure made from many layers of fiberglass; this actually hangs below the original vehicle floor. 
picture of the side of the motorized amp racks inside the best sounding van in the world
Here are just six of the 16 amps, held
in a pair of forced air-cooled motorised
amp racks. Even though none of the wiring
is going to be on display, it's all been
loomed beautifully. 
The tweeters also have one of these tasty-looking enclosures, but they are really there for cosmetic reasons. The two woofers are mounted in the rear section of the centre console using an aperiodic system to "...improve the load seen by the amplifiers and enhance the low-end response". All the speakers in the van have two sets of grilles, the idea being that when either the sound quality or the SPL systems are in use neither will interfere or be damaged by the other. And if you look at the quality of these grilles you just can't be anything but impressed. 

picture of rear door tool kit in the best sounding van in the world
Even the tool kit on the back door is all
Snap-On, well except for the Mag-Lite.
I wonder of they'll miss the ratchet
screw driver.
I knew that I was going to run out of space with this feature; there is just so much to cover. I haven't even had a chance to talk about the motorisation of the amp racks and the fact that there isn't one original panel in the interior - all of them have been custom-made. Then there's also the metalwork that went into strengthening the van ready to take the system and... You really have to make an effort to see this system when it's finished. The degree of work that's gone into every little detail is absolutely stunning. Nice one CAP!

Image of British Car Stereo & Security magazine's no. 52 cover.
Car Stereo & Security No. 52 Cover
Image of British Car Stereo & Security magazine's no. 52 index page.
Car Stereo & Security No. 52 Index Page

Image of British Car Stereo & Security magazine's Son of Seismic II article - first page
Car Stereo & Security No. 52 First Pages

Image of British Car Stereo & Security magazine's Son of Seismic II article - second page
Car Stereo & Security No. 52 Third Page
Image of British Car Stereo & Security magazine's Son of Seismic II article - third page
Car Stereo & Security No. 52 Fourth Page

Also, don't forget to check the past posts on this vehicle:

Car Stereo & Security No. 51 - Get Some Earth Shaking Bass Poster

Best Sound in a Vehicle - Part I - The Head Unit

Best Sound in a Vehicle
Can I brag? How much? Can I brag a lot? Is it bragging if performance is evidenced by the facts and certified by experts?