Wednesday, May 4, 2016

Dustin Culton's AC-Team Honda CRX

image of Cover of Autosound & Security Magazine March 1995
Autosound & Security Magazine March 1995
I call them my rock 'n roll years. There was a time when we looked for nothing more than driving into the sunset. Traveling the country in search of the nearest competition was almost as important as food and sleep; or perhaps more.
During the years when I worked for Stereo West, the leading retailer in the city, I was able to assemble a very strong competition team. But it was the combined effort of all salespeople, installers and customers that made the whole dream come true. And after everything was said and done, Stereo West became one of the top retailers in the nation, Joe Cavanaugh became a business leaders to the industry, my customers became world champions, and I had an opportunity to do an inventory of my life and change it forever.
But this is not a story of the ever-after. Instead today we will focus on part of the fun that made those years so cool.
Dustin Culton was one of our better known team members. Being a small guy, we surely picked on him quite a bit. Whether the reason was because he got a $400 speeding ticket outside of Memphis, or because he was afraid of a beggar at a fuel station in Indianapolis, Dustin was always a great sport. But in my mind he was to be always remembered as a great competitor. Dustin never gave up. The following is a short Winner's Circle coverage of his car  by Autosound and Security magazine published in March of 1995. Enjoy!

Black and White image of Dustin Culton outside of his 1985 Black competition CRX
Dustin Culton and his award winning CRX
Winner's Circle
by Morgan O'Riley

People compete for different reasons. Some do it because they lived on competition, some because there's money in it, and others because they're addicted. While not as caustic as smoking, competing in autosound can be harmful. Just ask this month's Winner's Circle guy, Dustin Culton of Omaha, Nebraska.
Black and White image of Dustin Culton's interior kickpanels
Handmade kickpanels for a MB Quart 5" and 1" component set
To get ready for the IASCA Finals this year, he ended up losing a 3-year-plus relationship with his girlfriend. Tuning and tweaking takes time and evidently she just wasn't willing to give up any of her time with Dustin. So it became the car or her. Looks like Dustin chose the car, because they aren't together anymore.
One person's loss is another's gain. In this case Dustin got everything ready for the IASCA Finals and hit the road ready to win. His 1985 Honda CRX has the qualifications too.
A pair of Punch 40s, some components up front and a pair of twelves might not seem like a whole lot, but in the small interior space of a CRX, you really don't need a lot; and the way in which everything is tied together in Dustin's car makes it more than the sum of the parts.
The installation starts out in the stock dash location with an Alpine 7807 CD tuner. The Alpine fits nice and snug in its spot, and right below that the center console section has been filled with a vinyl-covered panel with four rocker switches on it. The switches control things in the system like the neon around the amplifiers and a motorized panel in the hatch area.
Black and White image of the back hatch area in Dustin Culton's competition Honda CRX.
Dustin used up the majority of his hatch space with a pair of
MTX 12s, a pair of Punch 40s, fuses and more
After the tunes are produced by the Alpine, things head back to an AudioControl EQX. The AudioControl takes care of the system equalization and splits the frequencies between the two Rocker Fosgate Punch 40 amplifiers. The EQX is mounted out of sight on a hinged panel in the back. Set to operate with a linear actuator, the EQX motors up right in front of you when you lift the hatch lid. Underneath you get a neon MTX sign in a special paint job that looks like marble. Dustin likes to tell people he used marble for the job, but it's just paint applied with a feather in his sponge.
The crossover in the EQX sends the low frequencies to a Punch 40 that powers a pair of MTX Road Thunder Pros. The subs run 80Hz and down, and rock the little CRX.
The rest of the spectrum is covered by the second Punch 40. That unit powers a set of MB Quart components mounted in handmade kickpanels. A 5-inch mid and 1-inch tweeter where fitted low and angled to create a solid center image. For a touch of ambience, another pair of tweeters, Rockford 3/4-insurers, were set into the floor just forward of the seats - firing directly upward.
Black and White picture of the back of Dustin Culton's competition CRX. A motorized panel lifts an EQX and opens to show an MTX neon sign.
At the back of the hatch is a motorized panel that pops up
to reveal an AudioControl EQX and a cool MTX neon sign
Other cool little tricks that Dustin put into the system include mounting the amps upside down with the innards exposed, removable grills for all the components in the back, as well as tiny 2.5-inch LCD screens built into the sun visors. The screens can be used to play video games while you're stuck in traffic, or just to goof off.
Dustin is a member of USAC, IASCA and WAC. He attended over 20 shows in the '94 competition season, including the USAC and IASCA Finals. He's also proud to say that he did most of the work himself, but he'd also like to thank the guys at Stereo West for some of the work they did. While he didn't claim the title this year in the Novice 51-100 watt class, Dustin says he'll be ready to kick some butt next year in the Amateur class.

These are the whole page images:

Black and white image of page 61 of Autosound & Security Magazine's March 1995 issue.
Page 61 Autosound & Security March 1995
Black and white image of page 62 of Autosound & Security Magazine's March 1995 issue.
Page 62 Autosound & Security March 1995

Wednesday, March 30, 2016

Bad Judges or Bad Reference - Part II

I feel I need to further explain why is it that the Spring Break Nationals cars I heard were so bad?

composition image in four parts. First, micro musicians in front of larger microphones on a white stage. Second, micro musicians on top of a car dash serving as their stage. Third, real sized musicians on top of a car dash serving as their stage. Fourth, real sized musicians in front of microphones on a white stage.
Which is the real stage and which has the midget-sized musicians?
While there are a few other reasons, I will take a look at one property of sound reproduction that comes close to my heart; one that makes a big difference in the realism heard from the system.
In a nutshell, I am talking about designing a system with a very good step response. Read my previous posts and you will inevitably come across many mentions of the importance I place on this acoustic measurement. Good systems have a great step response and mediocre ones don't. It is a fact that remains independent of whatever else is done in the frequency/amplitude domain.
But why take my word for it? Why not look at what others comment, when unprompted.
Image of Quad ESL 989 electrostatic speakers inside a living room with many pink accents
Quad ESL 989
The one place where you can reliably get both, a good sound review and good measurements is Stereophile magazine. While it could be argued that The Absolute Sound or other international publications are superior at gauging realistic reproduction, none of them do measurements at the level of Stereophile. To me, the art must be matched by the science. Furthermore, the fact that Stereophile has many years of historic record keeping means that we can come up with some sort of statistical mean relevant to any kind of measurement.
Let's take two speakers from well regarded makers. Neither pair is cheap by any stretch of the imagination. Yet, one resides within the mid-fi world while the other sets foot inside the real high end.
I am referring to the NHT 3.3 and the Quad ESL 989 respectively. Yes for this comparison, I selected speakers that had been around a long time with the hope that most people would have heard of them.
The pair of new NHT 3.3's sold for about $4,000 while a pair of the Quad ESL 989's commanded a price tag of around $8,000. Such a small difference in price, yet worlds apart in performance.
NHT is generally a solid mid-fi speaker maker. Their products have seen strong following and plenty of industry accolades over the years. Still, theirs was never an attempt at the absolute state of the art, no matter what their marketing materials would claim. The fact remained that their path of choice was always one that kept them away from using the best components or having great enclosures. I remember a time when I did my usual ear-to-the-side-of-the-box test and was horrified by the loud ringing the speaker cabinets made. No high end manufacturer would ever allow for such large amount of energy to be dissipated in a poor and unpredictable way within the room. I also recall their engineers acting like I had just farted after I cringed from the disappointing experience.
image of black NHT 3.3 speakers inside a room with many wood accents.
NHT 3.3
But the real test, as always, is the listening session; an event that would further disappoint. While the speakers were bright and dry, what really told me the story about their heritage was how compressed the sound's physical dimensions were. The height of all instruments was ridiculously small. Depth was none and width was definitely inside the speakers; a fact that seemed difficult to conceive after taking in consideration the speaker's narrow cabinet profile, the asymmetric mid and tweeter placement, and their use of a felt strip next to the drivers. In other words, the engineers must have worked extra hard to make a speaker sound that bad considering how many other good things were going for it.
But enough of my opinion. Stereophile's Thomas J. Norton reviewed a par of NHT 3.3's for the magazine in 2005, after the brand had been acquired by Rockford Fosgate but before it was divested in October of that year. Believe me, it's a long story.
While the speaker received a good "B" rating by the magazine, Norton found it necessary to mention the following:

My rendition of a horrible Step Response curve on dark gray background of NHT 3.3 Speakers as publushed by Stereophile Magazine
"The 3.3s' soundstage was tight and focused, accommodating the program material both in the precision of its lateral detailing and in its depth. On some recordings there was noticeably less depth and pinpoint imaging than with soundstage champs like the WATTs/Puppies. But on others—the organ on Dorian's Pictures at an Exhibition, the synthesizer, vocalist, and chorus on Enya's Watermark (Geffen 242332), and the instrumental and vocal interplay on Eric Bibb's and Cindee Peters' Opus 3 compilation (CD 7706/03) jump off the pages of my listening notes—the depth rendition and lateral focus were all I could have hoped for. The only drawback I noted was a limiting of the soundstage to the space between the loudspeakers."

While the speaker played tones correctly, Norton made reference to the same kind of midget-image effect I described when talking about the Spring Break Nationals cars in my previous post. I mentioned that these cars tend to play ping-pong between the right and the left in such a way where the sound never goes past a very sharp boundary. It is also what makes some judges positively comment on how focused images are. Believe me, if instruments were midget sized, all the concentration of energy would always make them seem focused. But this effect is a distortion rather than a positive.
No, these weren't the only problems with the, so called, great cars. So hold back on your desire to jump to conclusions on the unfairness of my disappointment with cars that did some of what a mid-fi speaker do. Believe me, these cars don't come close to even the NHT's. But it is the flaw of compressed physical dimensions that I want to call attention to.
The distortion is so damaging to the reproduction that even Norton saw the need to compare the NHT's poor performance to that from the Wilson Audio's. I guess that great minds think alike.
And what's the reason for such dimensional distortion? Well, a poorly designed crossover network; one where part-count and cost are more important than performance. Take a look above at the impulse response as published by Stereophile in the same article. Each swing up or down is literally destroying the dimensional accuracy of the sound across progressively longer wavelengths.
Now, for the good news. Let's focus our attention on the Quads. The brand has been around for a long time and it is well known for making speakers of all sizes of an exceptionally predictable high quality. In my opinion, they simply never disappoint; even when considering that many electrostatics are notoriously difficult to set up.
In 2002, Larry Greenhill said the following when reviewing the Quads:

My rendition of an almost perfect Step Response curve on dark gray background of Quad ESL 989 Speakers as publushed by Stereophile Magazine
"The ESL989s' imaging was topnotch, conveying a seamless, wall-to-wall soundstage that did not seem to emanate from the speakers themselves. They captured the soundstage depth and width of "Naris," from Patricia Barber's Blue Café (CD, Premonition/Blue Note 5 21810 2). Percussion was open, airy, fast, and transparent. José Carreras in Misa Criolla was startling, his soft tenor in the foreground, a large, muted drum playing deep and to the left of center stage, backed up by the large, distant chorus. The perspective was spacious and eerie, suggesting the desolation and emptiness of a high South American plateau. Suzanne Vega seemed to materialize between the two ESLs, close enough to touch, as she sang "Tom's Diner," from Solitude Standing (CD, A&M CD 5136)."

Interestingly, there was one car that created a sound that could have been described by Mr. Greenhill's comments. But do you think that the show judges were able to recognize it's exceptional nature? No (in case you were looking for an actual response).
There is something pervasive about the soundstage of speaker systems with a triangular-looking step response. They are all big, rounded and well defined; whether from back to front, side to side or top to bottom. They are as close as space reproduction comes to being real. For God;s sake, just close your eyes and pay attention the the most basic of sounds. Don't be surprised if you don't find midget images anywhere.
Illustration of an almost perfect step response over a dark gray backgroundFor your reference, I am also sharing a model-based graph that illustrates the theoretically perfect step response.
So, could it be that the car that I am making reference to as having "conveying a seamless, wall-to-wall soundstage that did not seem to emanate from the speakers themselves" also has a triangular step response? Yes. This is something that any sophisticated professional listener should be able to easily recognize. Clearly there is no hope for the show's judges.
If you have any doubt, it takes an exponentially better engineer to design a system that does a good step response on top of doing everything else right. So, awarding a point or two of separation between the cars that do it and those that don't is simple wrong. A point or two are linear in nature while the performance difference is, again, exponential. This explains the exponential difference in price between the home speakers that achieve it and those that don't.
I remain terribly disappointed that Spring Break sound judges:

  • were not able to identify vehicles with compressed dimensional reproduction,
  • didn't know the exponentially higher value of achieving uncompressed dimensional performance,
  • and were not able to recognize the superior and more natural sound that comes from a well designed system. 

Tuesday, March 22, 2016

Bad Judges or Bad Reference?

In sound-offs many sound judges act as if they possessed a sound reference; an absolute reference to the sound being evaluated. They tell you that they know what the singer sounded in real life or that they know the band playing. Yet, these same judges fail time and time again when faced with exceptional sound. 
Why? Because their reference is flawed. They have been listening to too many cars, for one. A recent visit to the Spring Break Nationals event in Daytona demonstrated that most cars sound like not much more than a well tuned boom box. Yes, they are boxes that generally lack any sort of coherence when attempting to keep the projected image of an instrument in the same space and within the same dimensions. Even timbre changes as musicians shift up and down the spectrum of their instruments, making it seem as if multiple kinds of instruments are being played by the same musician.
So, why is it that these judges can't tell the flaws? Well, because they try to judge sound as if it was a point on a map. Once you get to that  point, your sound is good. But an absolute sound is not a point. If that was the case, one of the two recordings in this video would be absolutely correct and the other absolutely wrong. Yet, both are correct.

A good sound judge would know that. Both recordings can in fact be reproduced equally well. But fantastically well would never mean that the sound seems to be within a little box, which is what the so called best cars in the world sound like.
I suggest that these judges try to go to their nearest Wilson Audio dealer ASAP. They urgently need a reference. If the sales person actually let's them audition the speakers, they will hear how different these sound when compared to "the best cars in the world".
I have nothing for or against the Wilson brand, other than I wish they were much cheaper. But Wilson makes a fantastic family of speakers that are not spatially limited as are all other mid-fi brands. Of course that there are other good brands (Vandersteen, etc). Look for speakers with great step and polar responses and don't get too worked up with tonality, which any boom box with a thirty band equalizer can do ok with. But do consider the Wilsons. I just think that Wilson's focus on tuning their dealer shops pays big dividends every time.
But why not just listen to real music played life? Well, much of today's music is amplified, which means that you are at the expense of the many audio engineers with severe hearing loss that rule the world of pro-audio.
Now that if you have the time and the passion for listing to life unamplified music, then be my guest. Nothing compares to it. Professional musicians work harder than anyone I know and deserve the patronage. Just keep in mind that the actual reference that you will build will not be a single event or a single point on the map, as I made reference to before.
Instead, the real reference will be the memory of the beauty that real sound becomes.
Also, remember that to create such beauty, professional musicians have to make an exponentially larger investment. So, when listening to reproduced sound that captures the bigness and the nuances of their work, also acknowledge the exponentially larger investment required to achieve it.
In a nutshell, I think that today's sound off judges don't have either the knowledge or the guts to reward real high performance audio when they hear one. This is a shame because the tens of thousands of dollars invested by sound off competitors are being gambled through a random lottery system. It's all a real shame.

Monday, August 31, 2015

Jay's Escort - Real British Pride

Want to see more? Check out Jay Bow's Max Power article and then click on the video. But before, you may want to read my previous post about Jay Bow's family.

These images are from the pages of Max Power:

All pictures are property of Max Power Magazine and are used exclusively for educational purposes.

A Family Business

Imagine doing what you love with those you love. That was the case of the Bow family. Jim (dad), Geraldine (super mom), Jay (son) and Sasha (daughter) made up the most competitive sound off family in the United Kingdome. Their love for music was only matched by their love for their family.
When I entered the picture, they already had two very competitive cars that were winning right and left. Jay competed with his Ford Escort while Sasha run her Peugeot through the lanes. Both were very good. 
Soon after my arrival to England, we became acquainted. At the time they were supporting a competing importer. So our relationship was cordial but at arms length. Yet, things changed soon after I went to work for the company selling the products they promoted. 
After my move, I started coming to their incredibly gorgeous country house to watch Formula One races. Yes, not much NASCAR over at the old continent. Inevitably, the subject of improving their cars came up. I am not one to make people spend money for the heck of it. So I advised to keep the general structure of the cars and simply improve the areas that were either seriously under-performing or that had never been addressed at all before.
Since I had completely fallen off the installation wagon, I was not to touch their cars. All the installation had to be done by someone else. It is a real shame but the name of the installer escapes me. If you know the name, please share it with me so I may give him proper credit.
So, I was simply to design and to instruct the work. Then, when finished, I would help with the tuning. 
Nonetheless, I ended up breaking my promise since I did modify their electronics. As everybody knows, improving existing electronics is an art with very few participants to call for help. And since it is such an important aspect of a good system, I cave in. 
As the days and weeks passed, the cars begun to take shape. Jay's Escort matured tremendously from a very good car to an incredible one. 
Jay added waveguides. Lots of work had to be done to make their mounting surface rigid. Rigidity is something often overlooked by most, so called, professional installers. Many improperly confuse resin-over-felt with fiberglass, for example. They miss the fact that their concoction is missing the whole 'fiberglass' thing. just because the resin hardens into a glass looking rock, they think that it is the right stuff. Let's make it clear. if you take glass that is shaped as short strands and then you apply as little resin as possible, you now have fiberglass and not resin-ed felt. By the way, resin is a plastic.
These lost souls also miss the natural rigidity of fiberglass; especially when used as a constriction layer within a composite structure. When rigidity is done well, speakers that already display a high degree of transparency become as airy as the best electrostatics or plasma drivers. Of course that tuning the mouth of the waveguides following the art-form initiated by the Holdaways was key.
One of the problems often found with waveguides is the fact that it is hard to match their efficiency with that of most midbass systems. This is specially true when midbass drivers are placed on the doors. Considering an asymmetric seating position, which is normal in a car, it is inevitable to prevent synchronous right and left signals from canceling over a broad range of frequencies centered around 400 Hz. Bigger cars shift the cancelling range down slightly but still display the same phenomenon. 
As should be expected, cancelling midbass at 400 Hz, just an octave below the crossover frequency of most waveguides, renders the combination useless at best. To solve this, we designed a system where the path length of the midbass drivers was greatly increased. This reduces the amplitude of the cancellation and moves it to a much lower frequency; one that can be much more effectively dealt with through the use of a rigid and well sized enclosure. But since the ideal location needed to satisfy these goals was the floor of the car, using an exceptional speaker with a low physical profile lead us to the incredible Dynaudio speakers. Too bad that this manufacturer seized to sell their raw drivers to the many high end enthusiasts who revered them.
But what to do when you cover most of the musical range with incredibly well executed speakers? You match them with similar bass speakers located in the ideal location: the doors. To do this, the doors must be seriously rigid. We all have sat in cars where the doors vibrate. The feeling is terrible. Jay's car was the exception. This left the Dynaudio woofers to do their magic. When used in front of the listener, woofers tend to no longer bump. Listen to a high end home audio system, one where the speakers cost more than say $50,000. Notice that the bass is not the usual car audio bumpy sound. In fact, there seems to be no more bass; just instruments reaching all the way into infra-bass. This is why I love bass on the doors so much. It is so transparent that you can play it much louder in absolute terms and still sound boom-free. You see, bass in any other place in the car is coupled to the vehicle's surfaces and crevices. This coupling increases efficiency but at the cost of increasing audible color. Such color is what car guys recognize as bass. It is just that they have never heard real unamplified music. So, it is often hard to get this sort of bass to score as well as it should if other things are not in place. But when everything is right on, the degree of transparency leaves even the most skeptic of them all feeling a high degree of insecurity from daring to lower any of the sound scores. As a result, judges eventually come around.
To make all these speakers work, we deployed the best in conductor material and cable geometry I knew at the time. I know that many car guys think that car-wire is more than enough and that there is no right argument for the use of expensive home cables. I agree with them that I too don't like to pay a lot for anything. But where we disagree is on the issue of giving up performance just because the good stuff is more money than the garbage. I have conducted dozens of blind audience listening sessions where neophytes had to identify A or B in an A, B, C comparison. While they were often unable to eloquently explain the difference in performance, what they could easily see was the fact that there was a difference. So much for expert disagreement. 
In the case of Jay's car, both interconnects and speaker cables were over-built to display proper characteristic impedance and dampening factor. We made sure to reduce inductance in all cable applications to a minimum while keeping capacitance in check. Also, things like skin-effect-induced electron migration and quantum electron tunneling were deciding factors when selecting materials. 
Then came the electronics. I already said that everything was hot-rodded. If I only told you that the 30 band Lanzar equalizer operated at such high bias that it run very hot to the touch at all times. Translation, this close-to-class-A performance made the eq very sweet. It was very much like a tube equalizer would sound. 
But the sound improvements actually started at the source. No, I am not talking about the head unit. 
There was none. There was only a display at the dash and a pair of door-mounted controls anywhere near the listeners. 
No, the source was instead one of the changers in the back. The transport picked the digital signal and, after buffering it with a high bias precision op-amp, it sent it away from the factory circuitry and towards a custom preamplifier located just two inches-of-wire away. The Lanzar six channel preamp was gutted. The larger than normal power supply was made more stable. Then, rather than using stereo op-amps, precision mono units where used. 
The high power supply rails and their low impedance made it possible to operate the opamp at an insanely high voltage output level. We are talking well into the double digits and without attenuation throughout the system components. The motorized volume controls were placed right before the amplifier's pre-drive. 
This made the already quiet surface-mount Rockford amplifiers even more scary. It also meant that there was no Punch curve, Fader, Bass & Treble controls, etc., throughout the system, to damage the integrity of the music signal. The noise floor was also very, very impressive. Musical instruments would float in space surrounded by nothing more than the room they were recorded in. The short signal paths and attention to every capacitor, wire, inductor and connector detail resulted in waveguides that sounded smooth before being equalized. Anyone who knows about waveguides knows that these are beasts that must be tamed or else run the risk of constant threat. Waveguise love to eat listeners.
Well, not in Jay's car. His sound was as smooth as that from the best softdomes. No matter how much each equalizer band was increased or decreased, the constant system characteristic was that of total smoothness. Yes, rare indeed!
As I left the British kingdom to pursue other goals, things went very well for the cars at first. Unfortunately, the family later went through tragedy. Geraldine, the gravitational center of the family's soul, passed away. This broke everybody's heart, but specially those from her husband and kids. For all of us, Geraldine was as warm and mild as anyone can be. For her family, she was as stable and robust as the time-tested Greek columns that still support the Parthenon. No one like Geraldine.
Jim moved with the kids to his homeland of Australia. The love for each other remains strong, just as mom would have wanted it. But their sound-off years went to become just a memory; albeit a fantastic one. The Bow's will for ever be my friends no matter where they live. The three of them and their mom are perpetually in my heart.

All pictures are property of Max Power Magazine and are used exclusively for educational purposes.

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 immediately sensed 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...