Monday, April 21, 2014

What about Great Music

When writing the title to this blog, I promised "Music". Yet, I have failed to individually address this subject thus far.
Illustration of Musical notes over a dark background
This is terrible. After all, it is music that has driven my love for acoustics and electronics all these years. My understanding of physics was no more than an aid.
And when it comes to music, nothing gets me more emotionally engaged, positively or negatively, than reproduced music. In short, I think that most recordings are garbage.
I first observed that much recorded music was terrible at an early stage in my professional career. While loving a given song, listening to it often left me feeling empty.
It wasn't until I visited the music industry's best known trade-show NAMM in LA that I understood why I was so empirically disappointed. NAMM is where the biggest names in the music industry get together.
I expected to catch a few impromptu jam sessions by some of the best musicians. While I certainly witnessed great energy and spontaneity, what surprised me most was the fact that ALL (and I mean ALL) the musicians and music directors were deaf. Apparently, hearing-loss is rampant among the music pro's. Everybody sported either one or two hearing aids.
I then realized that what we all hear is the interpretation of people who hear through the equivalent of an MP3 player (a Walkman at the time). No wonder so many recordings are poop.
But the problem does not end with recordings. Witnessing your favorite artist live is also painful and disappointing due to the many blown eardrums that manage EQ's and processors at all venues.
close up photo image of Sarah Brightman
I once went to listen to Sarah Brightman. That she is gorgeous and petite is only the beginning. She has demonstrated great singing abilities in everything from opera to Broadway. But all my excited came crumbling down as soon as the first musical notes started. The highs were reaping holes on the venue's sealing. For a minute I even thought that perhaps I was being too harsh on the great Diva's team. Perhaps I was being too picky. Nonetheless, my self doubts lasted only until intermission. Once the lights came back on and people could talk, every lady sitting near me made the same comment about the terribly bright sound. The kind of sound easily created by a sound engineer with deficient hearing extension at the top of the audible spectrum. It was a total shame.
But the problem goes beyond tonal. Most recordings also destroy three-dimensionality. It is this that bothers me most, since it is what connects us closer to the original presentation than any other aspect of music. Good tonality can make music pleasant, but it won't show us the artist in the original space and time.
Moreover, when critically evaluating any audio system, what helps me quickly identify problems is the sound's dimensional properties. Any time errors, any distortions, any phase misalignments, all result in poor and specific spacial artifacts. Spacial reproduction is just brutally honest.
It is thus unsurprising that my favorite recordings excel at creating great and realistic spaces. Here, there is no other musical label that matches Reference Recordings' ability to create impeccable orchestral renditions. Beyond simply offering floating three-dimensionality, R&R does so with large contemporary orchestra ensembles. Any label can take one guitar and make it seem right. But try doing the same with grandiose attacks with the most dynamic instruments covering all segments of the audible spectrum and you are God.
Incredibly, Reference recordings creates recording after recording of superb quality. Among the often intimidating crescendos, one is able to see each instrument in its own space. Every instrumental texture and character are preserved.
Keith Johnson with his GRAMMY
Photo from Stereophile Magazine
"Prof." Keith O. Johnson is the man behind the incredible reliability and performance these recordings achieve. That he created the fantastic HDCD tells a lot about him That the format was launched just as DVD's begun to surge obscured his achievements somewhat.
Do you like orchestra? How about Big Band? Any piano? There is a great HDCD recording for all of these. R&R sells music directly to music lovers at great prices. They also make fantastic samplers available. All come with the same impeccably encrypted music quality. Even if you do not have an HDCD capable disc player, you will still get the benefits from the technology. I have conducted dozens (if not more) of comparisons on HDCD that I am comfortable using it any time and without thinking about it. I know that I will listen to superb musicality and realism.
If you would like to test my claims, try one of their samplers. I am absolutely sure they will not let you down. Unlike brands like Telarc that offered much but often came in short, R&R has granted me thousands of hours of utterly uncompromising pleasure. I wish you the same!



Friday, April 4, 2014

Almost like School, but not Boring

Many think about going back to school. I never left. Few things give me more pleasure than the process of learning something new.
Back in 1990, I had a job working for one of the pioneers in inbound telemarketing. I took calls for everything from The Abdominizer to the famous Dial MTV Hotline where people from all across America called to vote for their favorite songs.
composite image of The Abdominizer TV commercial and Dial MTV Hotline TV promo.
The Abdominizer and Dial MTV television ads
But I spent most of my time taking calls from California residents asking if the products they were using were known to cause cancer. The program was one of those brilliant ideas by a California senator that sounded good when the bill was drafted but which created absolutely no response from consumers after the money was spent. I am not kidding, I often went a whole week without receiving a single call. Sitting there was pure and unadulterated death.
Image of The Loudspeaker Design Cookbook by Vance Dickason over a tile table
The Loudspeaker Design Cookbook
by Vance Dickason
I probably do not have to say that telemarketing companies are known for their brutal business practices. But just in case, I will. You would get fired on the spot if you remotely looked like falling asleep; no questions asked and no apologies give. Even covering your face with your hands while handling a call was risky. So, the last thing I wanted to do was to just sit there and provoke termination. Since it was totally boring not getting calls, I had to do something interesting.
That's when I thought of learning acoustics. Yes! Most would have preferred something easier. But not me. As I loved car audio, I thought this would help me get better results with my car.
I was already very good with physics and math. I had even taken advanced classes on structures. So I just needed to apply what I knew to the science of waves.
I got my hands on everything available. Let's remember that those where the days where Google was not even a dream. To look for information required real commitment and follow through. I borrowed any text books I could. I bought the fantastic The Loudspeaker Design Cookbook by Vance Dickason. This book is pretty much the bible for anything to do with the art and the science of speaker making.
Speaker Builder and
AudioXpress Magazines
I spent hundreds of hours working though the math calculations until I intuitively understood how woofers worked within an enclosure. This fantastic book also helped me see how crossover networks react to speakers. The knowledge that I received in this subject was fundamental to help me later understand equipment loads and concepts like characteristic impedance of a transmission lines.
I then subscribed to Speaker Builder Magazine by Audio Amateur. This magazine was just plain fun. It later changed its name to AudioXpress and begun to mix speaker and electronic articles.
This publication proved to be the creative fuel that supercharged all my future system designs. Audio engineers and enthusiasts everywhere would work in the craziest of ideas. Have you ever seen a plasma speaker? They are both incredibly good and scary. They also don't last any time at all. They rapidly wear out.
How about monstrous concrete horns? Would you build one? For Speaker Builder contributors, everything was possible.
In contrast, researching any subject today is quite easy. I recently wanted to understand quantum tunneling; the effect that makes fusion reaction in the Sun possible despite the relatively low temperatures it has. To gain this insight, I took a couple of books from the local library and viewed a few dozen articles and videos online. For anyone with the ability to use calculus, with a little bit of patience and with an open mind, a working understanding of the quantum principles is realistic. As quickly as one begins, one gains new knowledge now that every bit of information is so readily available. What a fantastic time to be alive!
I will end by sharing this great video of Williams College physics professor Protik Majumder. Since what I love about acoustics is the music side more than math, I thought that perhaps you too would want to view a presentation that connects the science with the art. Enjoy!

Wednesday, April 2, 2014

Failing in Car Audio and a Very Special Comeback

Photo of 1991 Red Nissan Sentra owned by Alberto A Lopez for sound off competitions
Nebraska winters demanded
removal of all wheel hubcaps
to protect them from salt
What would you do after failing to build your small business ? I stood up and got to work.  
In my business blog I often discuss the benefits of allowing businesses the development of apprenticeship programs by removing the burden of a minimum wage. I argue that for workers without alternatives, working for a low wage is often the only way to get back on track. Of course that I speak from personal experience.
Photo of the inside of the truck in Alberto A Lopez's 1991 Red NIssan Sentra
Competitors used to make fun of
having an Audio Control Epicenter
while lacking any level of SPL
After failing with my small car audio shop in 1991, Inphase hired me for what could be called exploitative wages by those in government. But even to this day, I am still thankful that they did. They granted me the stage to build a come back.
Photo of the interior of Alberto A Lopez's 1991 Red NIssan Sentra
Cavalier Z-24 fabric used instead of
the cheesy Nissan factory plastic
While employed at Inphase, they allowed me shop time at night to work on my own car. After having experienced great initial success in competition the year before, I was ready to go all the way. This was especially true considering that at the 1991 IASCA finals in Oklahoma City, we did not receive a couple of our well deserved trophies due to mathematical score miscalculations. By the time the trophies made their way to us, several months had passed and the trophies were in terrible shape. We were denied the right to enjoy the winning circle in front of our peers.
Photo of the dash in Alberto A Lopez's 1991 Red NIssan Sentra
Even the Denon CD player looked
like it had been installed by Nissan.
I worked hard to build my Sentra for the 1992 Masters in Georgia but ended up finishing the install very late. While the fabrications were by far the best I had created up to that time, we faced driving none stop from Nebraska to Georgia. I did not sleep for six days trying to finish the car and to make it there. On the way there, I lost control of the pulling vehicle and trailer while driving down hill in Tennessee. After spinning, the trailer's axle broke and the car was damaged under the passenger door. Despite the bad luck, we abandoned the trailer and drove both vehicles the rest of the way.
Photo of the passive crossovers inside the front seats in Alberto A Lopez's 1991 Red NIssan Sentra
Front seat mounted crossover
networks basfled more than one.
After arriving, everyone was very impressed with the install. For the first time, a car displayed extensive passive crossover networks inside the front seats. Also noteworthy was the fact that the thin Nissan doors hosted 9" woofers while still allowing the windows to roll up and down. Finally, this was also the first time that someone was using the massive 9 Lbs Cabasse tweeters in a car.
Photo of the main speakers inside Alberto A Lopez's 1991 Red NIssan Sentra
For midbass, a ceramic 9" woofer.
For mids, a unique 4" driver with phase
plug and inverted surround. For highs,
a massive Cabasse tweeter.
But bad luck was to continue. While going through the RTA, the vehicle's curve would not go up to the reference level and the RTA judge refused to reduce the equipment's level; despite the fact that the rules clearly allowed for it. At Masters, the judges were so stressed out that they simply pushed everybody through. My RTA was very good, just not loud enough. Had they moved the window down three dB's the whole curve would had displayed complete while also scoring as good as the best. But with half of the curve outside of the window, the point deductions were simply too big.
Photo of the driver door of Alberto A Lopez's 1991 Red NIssan Sentra
While nicer that the cheap plastic
factory door panels, these still
looked Nissan approved.
My scores for sound and install were exceptional. But not enough to compensate for the low RTA. I placed well in my class but just missed going to Sunday for the big money show.
Nonetheless, it was all a dream to me. Those days were the funnest of my Audio career. I loved working very hard even when outcomes were not as good as they could be.
Photo of the rear deck's passive crossover network in Alberto A Lopez's 1991 Red NIssan Sentra
Passives, passives and more passives.
Even the rear deck had to showcase
a few of the network components
After coming back from Masters, I took a few pictures of my car (see all the pictures in this post) and sent them to Car Audio Magazine, at the time it was the best periodical in the world. To my surprise, the magazine accepted to feature the car in the prestigious Installations section; a fact that made me feel like walking on air.
Photo of the system diagram under the truck lid in Alberto A Lopez's 1991 Red NIssan Sentra
Trunk lid mounted volt meter
and system diagram
Later I would go on to much greater things. I built one of the most successful competition teams in the US.

We got to the point that we were getting so many trophies that we had no place where to put them all. In fact, Inphase and Stereo West still have all of mine. While doing car audio, I also went back to school; something that has taken me to great places around the world.
Photo of the passive network diagram under the truck lid in Alberto A Lopez's 1991 Red NIssan Sentra
I love passive crossovers. At the
time, I tuned all of them by ear. This
is the diagram showing the
many components used
But no future success ever compared to how great it was to be naively in love with Audio. I was happy to be given a chance. I am thus perpetually indebted to Dave Eary at Inphase for his trust.


Thanks to the many great moments the sport gave me, I feel to be a lucky man.

Tuesday, February 18, 2014

Q&A: How about woofers in the trunk?

A long-time close friend asked me a question that I felt merited sharing with everybody. He asked the following:

Question:
Grid with physical specifications for a car woofer
I wanted to get your opinion.  Looking at the Thiele & Small Parameters of this sub, I tried 1 and then 2 of them in Infinite Baffle. It worked okay, but didn't have a lot of pop. Which of these two options would you recommend considering the T/S Parameters of the sub?

1)  1 sub in a 1.7ft^3 sealed enclosure (either rear facing or down firing - opinions?) in the trunk right behind the back seat
OR
2)  2 subs in an aperiodic membrane, keeping in mind I have 3 openings in my rear deck, but no passthrough in the rear seat, so the rear seat won't ever fold down.

Answer:
When it comes to reproducing vibrations, which is what sound reproduction is, I believe that controlled and anticipated vibrations are much more desirable over uncontrolled ones. The reason is that controlled vibrations will at least have a degree of correlation and synchronicity with the music. On the other hand, uncontrolled vibrations may not. In other words, it is the degree of uncertainty that crates a problem. As a result, I prefer panels and enclosures that are as rigid as possible. I very much want for vibrations to be created only by the cone, ports or passive radiators based on the design.
Image of a home JBL three way speaker
JBL cheese
I have seen plenty of cheesy home speakers where the enclosure is said to enhance the sound through its vibrations. They somehow imply that the enclosure has become a musical instrument; like a violin that is supposed to vibrate as it creates music. The problem is that this is clearly no longer about reproduced sound. As such, those speakers will never reach a high degree of transparency; no matter how pleasant their new vibrations may be.
When placing woofers in the trunk of a car, I prefer to apply sound-damping material over the whole boundary section between the interior and the trunk. While not perfect, this material reduces leakage by a large margin, it's inexpensive and it's easy to deploy. I then cut openings only for the area where the woofer will play through.
If the trunk and the interior are also connected through the side panels, I would either apply expanding foam or stuff the cavities tight with fiberglass insulation.
The goal is to reduce the amplitude of any leaked vibration, whether airborne or not, by at least 20 dB's and to delay them by as much as possible.
A way to test this is by playing sweep tones and impulses through a wide bandwidth speaker inside the trunk before the final holes for the woofers are cut. Any vibrations, musical or not, that are audible will destroy image specificity and stage dimensions.
Here is where the problem lies. While the so called desirable vibrations of the cheesy enclosure described above may improve tonality, they will destroy spatial information. Even in the case where they project a larger stage, imaging will be bloated and all recordings will seem to be of the same stage size. This trick, again, should be left to poorly designed systems that attempt to impress unsophisticated listeners. While a neophyte will enjoy the cheesy system, they will intuitively know that something is wrong, even when unable to establish the source of the displeasure. 
illustration of acoustical vibrations
Unfortunately when competing in sound-offs, we are exposed to many sophisticated listeners. I know that I would certainly be able to pick the flaws and that any scores will reflect them. Those who know me have seen me score poorly a vehicle that would otherwise get decent scores. With my experience, it is difficult to get excited about cheap tricks.
Following the points addressed above, I am not sure that one woofer enclosure over the other would be better. Moreover, the woofer that you are using already has incredible Thiele & Small parameters.
You see, the pop that you are seeking is actually a distortion due to damping at around 40 Hz.
I should note that I have yet to hear the sound of woofers when listening to live, un-amplified music; let alone woofers that pop. This doesn't mean that the pop you seek would not be unpleasant; it would just not be linear.
A tight small sealed enclosure dampens the cone more at this frequency than a ported, infinite or transmission line. So, if pop is what you look for, then the answer is clear.
Furthermore, when it comes to pop, two is better than one.
With regards to facing the speaker towards the rear of the trunk or firing it directly into the interior of the car, I always prefer great quality woofers being fired directly. Firing back increases efficiency (loudness) at the expense of delaying the signal and increasing the uncertainty-risk by a large margin. This also means that sealing the boundary between the trunk and the interior will be impossible as the system depends on the sound getting through where the boundary would be.
Photo image of an open trunk where the kicker woofers are installed facing backwards
A woofer firing back in a trunk is therefore far from what I would consider for a system intended to have a high degree of linearity (accuracy). 
While uncertainty could be relatively reduced by using downward firing woofers, these still concern me enough that I would not use them as a top choice for a high linearity system. 
I like aperiodic enclosures better but these certainly lack the pop you are seeking. It was my experience that the lower the Qts, the better the speaker performed in an aperiodic. Your speaker seems to be right at the border of where it needs to be. You would just have to make sure to build the aperiodic rigid enough where there is no buzz coming from the fiberglass or packing material. 
illustration of the rear of an aperiodically dampened enclosure
I know that many judges like to hear some pop. This is the same challenge I faced when designing systems. I had to decide whether it was better to score high at a local level, where judging was poor, or to score higher at national competitions, where judging was better. My answer was to never compete locally where a bad judge could kill us in front of our crowd, to compete extensively at a regional level to compensate for any unlucky shows, and to focus on national quality shows instead. Thankfully, this approach also met my desire to build systems with superior linearity.

Wednesday, February 12, 2014

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

Not just any head-unit
Photo Image of British van built by Paul Richardson and Alberto A Lopez
Click to launch installation video
To create the very best sound system, every part of the signal chain demands exceptional attention to detail. After years of progressive electronics improvements, I know that small changes aggregate in such a way that the resulting musical experience bears no resemblance to initial impressions from original equipment. This belief guided Paul and I as we went on to construct the best vehicle in the world. We started with the best equipment available at the time and modified it until it sounded better, was more reliable, became much more beautiful and was markedly easier to use. The following paragraphs describe the changes made to the system's head-unit.

Fujitsu Ten Head-unit
Everything started when we received a Fujitsu Ten head-unit for the van. In the US, Fujitsu Ten sold the same head unit under the Eclipse brand, which in 2010 went into bankruptcy.
Logo of Eclipse by Fujitsu Ten in black background
Back in 1996, the Japanese factory reverted to their proud corporate name for the European market. It had something to do with the fact that the word Ten means Heaven in Japanese.
Needless to say, everybody over there wanted American Eclipse head-units and hated the idea of owning a Fujitsu Ten. But I knew they were both made with the same exceptional quality. So, I had no problem using one as the starting point of our new source unit. After all, it was Fujitsu Ten who manufactured many of the best head-units at the time. 
Today, CD players use digital processors capable of much higher resolutions. But at the time, there was nothing better than the Eclipse... I mean Fujitsu Ten.

Transport
photo image with labels showing raw installation of British champion sound system built by Alberto A Lopez and Paul RichardsonThe truth is that Paul and I were mainly interested in the Eclipse's transport and D/A Converter. These were as good as there was at the time. Moreover, the areas of improvement that represented the low hanging fruiit where elsewhere. 
We knew that by reducing power source ripple and minimizing the transport's electric load, we could end up with a very good and stable digital unit. 
To reduce ripple noise, we used a very large capacitor/inductor network. An 8 AWG inductor is first placed in series with the load on the positive cable going to the head unit. Next, a large capacitor is wired in parallel running in between the positive and negative power cables. You then repeat the same inductor in series plus capacitor in parallel filter. While overkill, this setup proved quite effective at stiffening the head unit's power supply. 
To reduce the transport's electric load, we added a custom external power supply that drove an external pre-amplifier. The power supply was wired separate from the transport and had its own capacitor/inductor network.
After the modifications, the CD player lost all of its operating features. AM/FM radio, Volume, Balance, Fader and Tone controls were no longer active. In a nutshell, all that remained was the transport. All the duties of the Display, Controls, Volume and Output, were handled by separate devices placed elsewhere in the van. 

Photo image of center console inside the sound-off champion van built by Paul Richardson and Alberto A Lopez in 1996Center Console

The CD transport, the pre-amplifier and its power supply were installed within a new center console. Their 3" height determined the minimum internal dimensions possible for the console. Since we wanted the console to have the least effect over the sound of the floor speakers, we needed it to be very small. In the end, we made it about 3 3/4" high. 
After we finished, there was really nothing visible that would indicate that the electronics were contained within the unusually low console. There was only a very small slot facing the driver side.
Close up photo image of center console inside the sound-off champion van built by Paul Richardson and Alberto A Lopez in 1996A slot was precision cut out of a black acrylic layer. So, considering that the interior of the van was all black, it was difficult for anyone to know that the CD player was housed there. This was the maximum expression of a stealth installation. 
Despite the unusual nature of the location, CD's were surprisingly easy to insert without looking. The reality was that placing the transport there was ergonomically superior to the more common dashboard location. In any case, it was very cool to take a CD and insert it into the invisible slot. It was as if the discs magically disappeared within the center console.

Pre-amplifier
If there is something that we all learned from Richard Clark was the value of a constant high voltage output from a head unit. This allows the signal to display a much higher degree of immunity to induced noise than is normally the case. Furthermore, a constant signal level means that processors behave much more linearly than they would otherwise. On its own, music is very dynamic. This poses a massive challenge to any power supply. But if you then add a volume control, you ask for the impossible. The dynamic range and response speed of such supply would be unique to say the least. Without such demand, dynamics improve as the signal is pushed hard through signal processors. 
The preamplifier took the output directly from the OpAmp buffering the D/A converter located on the unit's transport circuit board. As it is normal for me, we changed the buffer from the piece of garbage use by Eclipse to a superb Burr Brown. At the time, Burr Brown was yet to be bought by Texas Instruments. With Analog Devices, they represented the highest standard in performance. In comparison to other OpAmps, Burr Browns were sweet, spacious and large. But don't ask me which one we used. I can honestly not remember. All I remember is that it operated with high bias and that it was orgasmic in the way it played music.
By using a very small high quality cable, we reduced the signal's path length and bypassed  all the unnecessary radio and preamp features offered by Eclipse. In other words, there were no Volume, Fader, Bass boost or other features that could distort the signal. The difference in sound when one does this is incredible. The degree of transparency achieved is much higher.
To create the preamplifier, we started with a Lanzar six channel line driver. We disconnected the internal power supply and connected the board to our new external +/- 15V regulated power supply sporting a very low output impedance. Then, the input and four of the outputs were removed. Finally, two single channel Burr Browns were used in place of two of the original dual channel OpAmps. This meant that we ended up with a true dual mono line driver. Our goal was to improve stereo separation. In high definition systems, better separation and symmetry result in solid imaging and an expansive stage.
We then cranked up the gain until the Burr Browns begged for mercy. The line run hot at all times. There was no attenuator at the head unit. Instead, we installed ALPS motorized attenuators after the processors and right before the amplifiers. With what I know now, I would have used a better volume control. The difference between the ALPS and the one I have in my system now is like night and day. The ALPS lacks transparency. Here, consider the fact that I paid about 40 times more to build my present volume pot than to buy the ALPS already made. So the comparison isn't fair.
Likewise, comparing the ALPS with pots commonly found in car audio equipment is like comparing an MP3 with a High Resolution signal. There is just no comparison. The ALPS is much better than regular car stuff. Several layers of grain were removed thanks to the ALPS.

Photo image of hidden head unit display inside the sound-off champion van built by Paul Richardson and Alberto A Lopez in 1996LCD Display
Can you imagine what it would be like to try to navigate CD tracks without a display. We took the front circuit board from the Eclipse unit and placed it behind a custom piece of sculpted acrylic in the upper center section of the dash. Because the acrylic piece was painted black from behind, the display was completely invisible when off. As the head unit was energized, the display would appear, seemingly out of nowhere. This perfectly matched the disappearing CD trick described above. 
photo of Eclipse head unit's front board with connecting wires coming out of it.Unfortunately, to simply wire the front circuit board that housed the display to the body of the CD player would result in failure. How do I know? Well, because we failed when we tried it. What happened was that the long cables acted as capacitors. So, after we would remotely activate the "track up" feature, for example, the stored capacitance would keep it on; thus stopping all other features from working. Incredibly, the cables held enough capacitive energy to last for quite a while. This meant that we had to use a different solution. Let's just say that we ended up using telecommunication micro-relays to make the controls work. 

Photo image of control panel inside the sound-off champion van built by Paul Richardson and Alberto A Lopez in 1996Control Panel
The one part of the head unit that users experience directly was the control panel. This one was located in the best ergonomic location possible. While seated, the vehicle's driver would just slowly rest his right arm and, where the hand landed, that was where the controls were. 
We created a durable membrane that was stretched inside of the panel's top lid. Behind it, an aluminum frame holding low-travel (0.5 mm) precision switches held the rest in place. By pressing the membrane over each of the illustrated button images, the switches below would be activated. Each of these switches would then control the micro relays located behind the display board. Then, the volume up and down switches controlled the motors of the attenuators located at the amplifiers.
Photo image of control panel being operatedIn this way, all volume, track and power on/off functions were centralized within easy reach of the users. This meant that a seating listener would insert the CD through the stealth slot near his knee. He would then operate the system through the control board while visually confirming everything through the display located just below his sight. When compared to other vehicles, the experience of listening to the van was indeed exceptional right from the moment the disc was inserted and the system turned on.

Photo image of ventilation system inside the sound-off champion van built by Paul Richardson and Alberto A Lopez in 1996
Ventilation System
Part to impress the judges and part to prevent any possible issues with heat, Paul and I created a ventilation system that would keep the transport, the power supply and the pre-amp running cool. We used very quiet fans that could be turned off during listening sessions. 



Fuse Protection
Finally, we had to have the best protection. While most sound-off competitors create installations without access to the radio's fuses, our van was designed to be much better. All fuses where placed right where the driver's left hand would hang when not holding the steering wheel. In this way, the van's conductor would have access to all components of the head unit without having to exit the vehicle. Everything was easily reachable from a comfortable sitting position. 

Ergonomics
Photo image of interior of sound-off champion van built by Paul Richardson and Alberto A Lopez in 1996And there was nothing as comfortable as seating in the van. We raised the floor to ensure maximum leg comfort. We selected firm, wide Recaro seats for the beast support. These seats were located very close to each other to improve speaker path length symmetry. Finally, all windows and windshield were darkened with 30% film. To me, there is nothing like the impression of peace and quiet that results from the psycho-acoustical response to darkness. Think of light as energy. Then think of this energy as noise that interferes with the music. Light energy is, after all, uncorrelated to music.

How does it compare?
While Pioneer had already created its fantastic ODR system by the time we built the van, business issues meant that we would not be able to use it in the UK. Nonetheless, I am comfortable stating that our final head unit largely outperformed even a hot-roded ODR. Chuck Barbosa used such ODR, modified with Burr Browns and superior components. But the musicality and the dynamics from our Eclipse unit were simply out of this world in comparison. The only feature where the ODR won hands down was in time compensation. The Eclipse didn't offer any. Thankfully, time compensation was not needed. Paul and I selected speaker locations with the longest path lengths possible within any car. The resulting symmetry was unique. Then, speaker locations compensated for the natural delays affecting all speakers driven with low-pass signals from a crossover. You see, time delays are more valuable as the system quality decreases. This is why high end home speakers like Wilson Audio's achieve the most three dimensional musical reproduction without digital time compensation. 
photo image of night concert at amphitheater
Thanks to speaker locations, the van's boundaries disappeared when playing music. The stage's width and depth seemed to extend into the horizon. It was like listening to an orchestra in an open amphitheater rather than the usual enclosed theater. In comparison, the best cars at the time sounded like lunch boxes. Without proper speaker alignment, this would have never been possible. But rather than using a patch for the problem, Paul and I eliminated the problem right from the beginning. 
In the end, Paul and I bridged the gap created by a massive ocean that separates our two nations. We brought the best from British and American know-how. We created a vehicle that although American in heritage (it was a Chevy Astro van with a Corvette engine after all), it was very British. The sound system demonstrated a complete lack of fear of innovation. It was quirky as many British masterpieces are. It was as elegant as a James Bond super car. Finally, it created beautiful music as only the Brits know how to. Oh, how I miss that sound!



February 14, 2014 update:

After publishing this article, I received what I thought was a great question from a close friend whom I admire very much: ├╝ber world champion Ron Baker. I hope that you find our exchange insightful.

Ron Baker:
"Speaking of head units, would you say that the head unit and processor are the more important items in the signal path?  Then, within the head unit, I would suspect that the most important part is the transport. Finally, the processor would do the heavy lifting."

Alberto Lopez:
"Ron, I am not sure that any one part is superior. I think that when we listen to reproduced music, we in fact hear a layered picture made up from the combination of the characteristic sound of all components in the signal chain. Improving one makes the new picture better but it isn't free from the problems of the other parts. 
If my thesis is correct, then it would make sense to try to improve every part of the system. Moreover, it would also suggest that fewer, as opposed to more, system components in the chain should perform much better. Both of these observations are supported by my empirical observations."

Tuesday, January 14, 2014

Out-of-the-Box Tweeter Enclosure

If woofers can be boxed in, ported and transmission lined, can the same be done with a tweeter? You betcha!
As it should be evident from looking at the installation book of the British van I built with Paul Richardson, I like modifying tweeters. This time, I would like to share the diagrams that I created for one of the most famous competitors in the circuit ever. These modifications are based on a Morel tweeter with a built-in aperiodic enclosure and a third magnet designed to short the magnetic field.  

illustration of a cut off of a dome tweeter with Aperiodic enclosure behind the dome and double magnets shorted with a third magnet.
Illustration of original tweeter with aperiodic enclosure
and double magnets shorted with a third magnet.
Not satisfied with already having a tweeter with an actual fancy enclosure behind the dome, I had to push performance beyond the normal, if an aperiodic could be considered normal. 
Over the years, I have come to trust the power handling ability and reliability of the larger Dynaudio and Morel dome tweeters. Focal tweeters have a smaller voice coil which limits how far you can push power handling. This is important when working on an enclosure that can't normally be reversed after being applied to an expensive tweeter. 
My own home system tweeters use a small transmission line. As a result, their transparency is incredible. They just do not sound like the usually euphonic Dynaudios. Mine are much faster and transparent. They almost resemble ribbons. At times, it even seems as if the tweeters have completely turned off; a characteristic also noticeable when using the stupidly expensive diamond-dome Accutons
But my transmission line is a little too long for a car. To gauge what I am attempting to describe, consider the fact that the Morels here described are already larger than most midrange speakers. 

illustration of the cut-off of a tweeter after enclosure modifications
Modified tweeter with extended enclosure 
Carefully, I drill the back of the chamber making sure to not damage the magnets. A Unibit step drill comes in handy here. All drilling must be done slowly and with lots of sticky tape to try to prevent all metal shaving from going into the tweeter. In fact, I normally remove the dome and place a protective cover over the magnetic gap. I like using double sided tape that is flexible and very sticky. 
Applying this protective tape is a little difficult with tweeters with ferrofluid with in the voice coil gap, but this never stopped me. I have been known to ask the factory for extra ferrofluid for after the surgery. 
Yes, by now, your manufacturer's warranty is gone. As if this was not enough, you are doing the mods at your own risk as I am not doing them for you. 
I look for a rigid tubular shape of approximately the same internal diameter as the inside chamber within the tweeter to extend the cavity. Aluminum pieces are always welcomed. This outside tube will have to be capped and adhered to the back of the tweeter. A slightly larger diameter is preferable to a smaller one to prevent the creation of a highly diffractive edge midway through the final cavity. 
How you do this portion of the project will depend of the circumstances and your imagination. The only thing that is most important is that the connection between cavity and tweeter must be as rigid as possible. A vibrating rear extension will defeat the point of the exercise. 
illustration of a hand cleaning a window making it more transparent
Better Transparency
I like applying felt to all internal surfaces. If possible, I try to insert felt into the tweeter's old chamber as well. Just make sure that the dome will not touch the felt during play. I suggest getting the felt from art and craft suppliers like Michael's. make sure to dedicate enough time to ensure this process goes well. Think more like a Swiss watch maker than Joe Butch at your local mechanic's shop. Finally, get a little bit of fiber glass that can be stuffed within the extension and even within part of the old cavity. How much fiberglass? Enough to ensure that midrange energy that travels towards the back of the tweeter significantly drops in amplitude before it makes it back to the front.
The whole idea behind this mod is that normal tweeters create rear pressures that hit the solid components behind the dome and then return and actually cross the dome to become audible. These distortions thus exhibit a lag in time and are asynchronous with the music. Typically, the lower the mass of the dome, the more susceptible the tweeter is to this effect. With a chamber that prevents much of this reflected pressure from making it back to the dome, the tweeter is left playing sound in response to voice coil impulses only; which is how it is supposed to operate. In a nutshell, the sound is very transparent after this modification. The only caveats are that this mod is not for first timers and that experimentation is acceptable. Without enough experience altering speakers, you may destroy your first expensive pair. 
Moreover, I have tried to model the right levels of felt and volume of additional cavity by using the same formulas as with woofers but the results are unreliable. The main reason why is that the dimensions associated with this exercise are much smaller than when dealing with woofers. So, I have learned to trust experimentation as a way to fine-tune the components. Again, if in doubt, don't start the project. 
I hope that you have found the idea useful. If you do not get the urge to modify a tweeter, at least you now know that you can treat them like you would other larger woofers.

scan of installation book from British van that I helped build
Modifying a tweeter;
circa 1996
scan of installation book from British van that I helped build
Testing the outcome

Sunday, January 12, 2014

Sound-off Bullying - Poetic Beginning to a Great Run

Sound-offs can be both fun and stressing. But in all cases, bullying is unmerited. My advice, don't sink to their level. Like Chuck, take the high road instead.
International Auto Sound Competition Association Logo
International Auto Sound
Challenge Association
This is a short story of an IASCA Eastern regional event my team and I attended around 1995. Exactly when in 1995? I can't remember. So, don't mind my complete inability to remember the precise date; these events happened a long time ago. In any case, the essence of the narrative has nothing to do with time. It is all about the beginning of something awesome. 
Chuck Barbosa, now a serious Kansas City SWAT officer, was once a lost audiophile punk like me. One day, I convinced him to enter one of the most challenging shows in the US. Prior to working together, he had not had much luck at big venues; so Chuck was not too excited. But he obliged in the end.

Battered Spirit on Saturday Morning
On the morning the first day of the event, Chuck was finishing detailing his car when a famous competitor approached him. “Nice car” he said. “What class are y'all in?” Chuck competed in Amateur 251 to 500. “Damned boy, if I was you I'd stop cleaning the car and start tuning. Do ya know that red truck over there? That truck is gonna whoop you boy!”. And after pointing at his teammate's red Florida Mazda he walked away smirking and shaking his head. Needless to say, Chuck was devastated.
When Chuck told me, I replied “So what? What do you worry about? If they are better, you’ll loose any way. But they are not the judges. You just do your best and leave the rest to the real judges. The guy was just trying to intimidate you. Don’t pay attention.
I had known this guy for a few seasons but he didn't know much about Chuck and what we had done with the car. He was therefore talking out of his rear.
Chuck decided to trust on our preparation and did a really good job presenting the car.

Award Anxiety Sunday 
Trophy time arrived. Those were very competitive events when plenty of good cars battled for the last few points. Being that his new system was being day-viewed, we had no idea what to expect.
Fifth place was called. Then came fourth place. Third place went to the very good red Mazda truck. Chuck feared the worst and begun to walk away. Second place went to another impressive car.
Totally numb, Chuck didn't recognize his name when called for first place. “That’s you Chuck” everyone who knew him yelled. His smile couldn't grow any bigger. The whole thing erupted into an applause frenzy. Many people knew Chuck's incredible dedication and his previous lack of success.
Still floating, Chuck once again missed his name as Best of Show Amateur winner. It could not get any more surreal! He was finally on his way to becoming one of the most decorated sound-off competitors in the nation.

Sweetness
As soon as the last trophy was awarded, I asked Chuck, who was still glowing, to follow me with his two trophies. We walked towards the guy and, after congratulating him for his trophy, I followed my smile with "I came to introduce you to my new protegee. Meet Chuck".


The following are a few old pictures and a video of how Chuck's car looked at the end of the 1995 season (I will discuss the features in a future post): 







Photo image of the outside of the car (with the engine compartment opened) of Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Outside of the Red Laser
during winter storage
Photo image of the outside of the car (with the hood opened) of Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Vehicle exterior as it looked
at the end of the 1995 season

Photo image of the engine of Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Lots of chrome and 3/8" acrylic

Photo image of the engine compartment of Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Engine compartment



Photo image of the right open door with speaker grills of Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Right door with midbass grills





Photo image of the right open door without speaker grills of Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Right door with grills removed





Photo image of the front interior showing the very small kick panel in Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Front-interior
with very small kick panels


Photo image of the front interior showing the motorized CD changer and head unit in Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Front-interior with motorized
globe box and head unit





Photo image of the rear interior showing the power distribution panel behind the seats, the ODR system inside the motorized rear seats, and the amp rack being motorized upwards in Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Fuse distribution behind the
motorized rear seat



Photo image of the rear interior showing the rear seat area after being motorized back into position in Chuck Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Closed rear seat




Photo image of the rear hatch area showing the woofer box, the battery rack and the amplifier rack being motorized up in Charles Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Rear hatch area
with amp motorization,
woofer box and
battery compartment


Photo image of the rear hatch area showing the woofer box, the battery rack, the motorized amplifier rack in the down position and the rear seat with the ODR system after being motorized open in Charles Barbosa's Red Laser as it stood during the winter storage at the end of 1995 and beginning of 1996.
Rear hatch area
with amp rack closed and
motorized rear seat
with ODR system