Audiophile Musings

Monday, December 3, 2012

Bozak Rebuild Project - Part 1

Most of you know that I have rebuilt a pair of Bozak B-302A speakers being as true to the original design Rudy Bozak used for this model as possible. Several other folks (Tobin) have modified this stock crossover network replacing capacitors and adding attenuation to the tweeters to upgrade this design. This modification balances the SPLs between the drivers, something desperately needed as you will soon see. While doing so retains the original sound and improves clarity, I wanted to take this design a step further and apply additional knowledge that was unavailable in the early 1960s. Let’s see what I found from the work of others and what I did to improve it.

Original Bozak B-302A Urban Built in 1963

I used the original woofer enclosure (about 5¼ cubic feet), added a second woofer in an isobaric push-pull configuration, and built a truncated pyramid (non-parallel) 1 cubic foot infinite baffle satellite box to house the mid and tweets (added two more tweets per speaker). I also mounted the stock crossover network board onto the rear of the woofer cabinet to permit quick tuning adjustments, changed all wiring to OF-HC star-quad copper (4 x 12 AWG), and bi-wired the system to the amp. I finished the speaker tops off cosmetically with a piece of 2” thick granite that helped to mechanically isolate the two enclosures from each other. Speaker spikes to both the woofer and satellite boxes topped off the mechanical design.

Enclosures for the Bozak Project

Below is a picture of the enclosure and rear-mounted crossover before removing the old speaker terminals. Internally mounted woofers are down firing, hard-wired to the network, and stock legs moved to the face. The speaker spikes raised the height of the legs enough for the pull woofer to clear the floor by ½”.

Original Rear-Mounted Crossover Network

Before tearing apart my Bozak crossover network, I decided to make a few measurements with that RTA Pro software I have been telling you folks about to establish a baseline. I made all of the pink noise measurements in all of the articles that appear in this blog about these speakers from the same position in my listening room. Below is this reference RTA image showing crossover points with the original crossover, upgraded capacitors to Clarity SA of identical values, and a -16dB T-pad attenuator on the vertical four-tweeter array.

Where This All Begins

While the above graph clearly shows the inadequacies of the room+speaker, I decided to tune the crossover network to the room instead of using the conventional anechoic approach (after all, I would have to adjust the EQ of the system again which seemed like a waste of time).

Despite the huge swings in SPL (+/- 10dB!) and the nasty goings on at 4-6KHz, the system sounded amazingly good. I used several reference tracks to determine what was right and what was wrong with this design including Dire Straits “Brothers in Arms,” Norah Jones “Nightingale,” Eric Bibb “Tall Cotton,” Cirque du Soleil “Taiko,” and Eric Clapton “Change the World” among others.

To start, the system fell flat over 8KHz with zero sparkle in the top octaves, something I was used to with my previous ribbon tweeters and missed dearly. Transient response was frighteningly excellent with moments of shock and surprise when explosions from movies rocked the room and the ease at high SPLs was unstrained and exhilarating. It was a very different sound from the 12” B2 medium sensitivity system I outgrew even with its Dynaudio D-54 midrange driver, one that was very revealing of instrumentation and nuances in musician technique.

For example, the fingering of Clapton’s acoustic guitar in “Change the World” was brisk and succinct without ringing or edginess. But voices were brighter and the absence of the top octave very annoying. Inner detailing of any percussion was totally absent so the first adjustment to the design required the addition of a very high efficiency super tweeter to match the efficiencies of the rest of these amazing Bozak drivers. But there was something about the midrange that kept me going. Maybe it was the air of the aluminum cone or the striking accuracy it revealed, but whatever it was, I am very glad I persisted over the past 12 months to improve their character instead of assigning these speakers to the “failed attempt” heap.

Rear View of Satellite and Network

From this starting point, I began the quest to tame the peaks and address the valleys of this radically new design. The remaining parts of this blog will help you understand what designers go through when tuning a speaker and may inspire you try a few things on your own.

So fasten your seatbelt and make sure your trays are locked in the upright position. We’re headed were no one has gone before and doing so with as little engineering-speak as possible!

This series is continued in Part 2.

Yours for higher fidelity,

Philip Rastocny

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.

My other titles include:

Althea: A Story of Love

Build an Extreme Green Composter

The Extreme Green Guide to Wind Turbines

Build and Extreme Green Hot Water Solar Collector

The Extreme Green Guide to Solar Electricity

The Extreme Green Guide to Improving Mileage

Meditation for Geeks (and other left-brained people)

Build an Extreme Green Raised Bed Garden

Build an Extreme Green Rain Barrel

Build an Extreme Green Squirrel-Proof Bird Feeder

Extreme Audio 1: House Wiring

Extreme Audio 2: Line Filtering

Extreme Audio 3: Chassis Leakage

Extreme Audio 4: Interconnect Cables

Extreme Audio 5: Speaker Wires

Extreme Green Organic Gardening

Extreme Green Organic Gardening 2012

The Extreme Green Appliance Buying Guide

Tuesday, November 13, 2012

Picking Apart the Sound

Being a high-end audiophile means that you become critical of your system as time goes on. You hear things that other systems do and constantly compare what you hear to what yours does - or does not do. You either like or dislike the percieved difference. When you hear something you like, you entertain the possibility of adding it to your system.

Sound like familiar behavior? I bet it does. I am struggling with part of the band above 2,500 Hz in my Bozak speakers and although to others they sound fantastic, to me they sound off compared to the best systems in my sonic memory combined with what I know instruments really sound like. I am studying the issue and trying to decide how to put my concerns to rest. A week ago, after enough RTA measurements and enough analysis of the crossover network, I discovered a few things about the Bozak drivers that I overlooked in the past (yes, I too make mistakes).

The midrange driver has an aluminum dust cap along with its aluminum cone to improve dispersion and extend its bandwidth. It is this aluminum domed dust cap that is causing my distress and influencing the sound of the tweeters in their operating bandwidth. Rudy Bozak decided to use a first-order Butterworth crossover network to minimize phase issues and rightfully so. But the rising sound pressure after the crossover point indicates a mechanical resonance beyond the prresumed supression point that needs to be tackled if my ears are to be pacified.

I have two multimeters that read capacitance but none that read inductance, the two components used in passive crossover networks. So arriving in the mail last Friday was a new inductance meter and now I am set to redesign the Bozak network to suite my personal acoustic preferences. Hopefully over the next few months, I will succeed at this feat and tell you of my progress either good or bad, but with the holidays coinciding, the amount of time I have between getting my next book out and improving my system is VERY limited.

I have been pushing to get my next book out before Thanksgiving and I now realize that despite the fact that the first draft is written, the final product is still many weeks away. The new goal is for the pre-Christmas holiday and I am committed to making this happen. So I must take off a while from this blog and focus my attention on the book - a book about why we choose the things we do and how we can understand our patterns so we can make different choices.

There was a period in my life when Tony Robbins and other well-known professional coaches were my main pursuit and what I learned from them combined with my own insight is where this book has gone. It will be written to those who are unfamiliar with the workings of the conscious mind and want to figure out how to change things from a fresh perspective without getting into that heavy psychiatry realm. I hopeit will be a winner since I believe that everyone could benefit from understanding why we do the things we do.

Yours for higher fidelity,
Philip Rastocny

My other titles include:

My Other UFO Encounter

I was in the USAF in 1969 stationed in Altus, Oklahoma. I was an assistant crew chief working on C-5A Starlifters and going home to Wisconsin on leave over the Memorial Day weekend. I planned to paint my motorcycle and get together with friends and family, folks I had not seen for years.

Working the swing shift, I ate a quick breakfast at the mess hall and signed out on leave at 12:01AM on Saturday, May 31. I took the front wheel off of my Honda 160, turned the seat sideways in my 1963 VW Beetle, took off the handle bars, and put the bike inside the car, back wheel in the back seat. It was a cozy ride and I was going to paint the bike once I got home. I drove north from Altus to I-40, east to Oklahoma City, northeast on I-44 to Tulsa, and then continuing on the I-44 toll road northeast toward St. Louis.

My black '63 bug was spartan: seats, steering wheel, and four tires, no radio. With my Honda 160 keeping me company, the hum of the tires and the wind noise were the only audio companions I had for this 1,000 mile long trip across country. At about 4:00AM, I pulled into the toll booth northeast of Tulsa heading for the northeast corner of the state. The truckers would take US 66 avoiding the tolls so I had the road pretty much to myself at this time of the early morning. It was quiet and the constant hum of the tires at 70mph created their own one-note song.

Once passing the Vinita exit, the road ahead was barren and farms were huge and far apart. The terrain started to change and the rolling foot hills of Missouri caused my little 1300cc engine to struggle going up the ever-steeper grades. It was a moonless morning and I was looking forward to the dawn and getting off of this quiet toll road and back into heavier traffic. It had been about a half hour since I passed anyone and I was speeding, well the best I could given the size of the engine and the load it carried.

Passing a hill on my left, I noticed what appeared to me as a helicopter swoop around from its far side heading toward me. I believed that I had been clocked on radar and so I immediately slowed down expecting that over the next hill would be a police car waving me over to the shoulder. My mind searched for a reasonable explanation about why I was speeding and decided as I crested the hill just to tell the truth and see if they would let a G.I. off with a warning. Over the hill I drove and there was no one there.

Hmmmm...next hill for sure. Nope. No one. Things were not making sense so I looked back at the helicopter who was drafting me to my left and just behind me. I glanced over and saw it flying about 30 feet off the deck and just beyond the fence that kept the cows from wandering onto the highway. This was strange. There was something else that did not add up and as I strained to see who was inside the blunt nosed craft, I saw two figures behind the windshield illuminated from the green glow of the instrument lights. One pointed at me and then I realized what was wrong. There was no engine or rotor noise.

For the first time in my life, I understood what the feeling of the word panic meant. Here I was alone and in a deserted part of the state being drafted by a UFO. I paid more attention to the structure of this craft since I understood that it was not of this world. It was cigar shaped with a fuselage that resembled a C-47 minus the wings. Totally so black that I had to strain to see the shape as it moved between the background and my eyes. Except for the cockpit glow and flashing red light at the rear, I could not believe what my eyes were telling me. "There has to be engine noise" I said to myself so I put in the clutch on my VW, rolled down the window, and stuck out my head. The only thing I heard was the wind in my ears, the engine idling, and the tires humming on the pavement. Yup, this was a UFO.

There are two stories that go on from here: the one I believed right after the incident and the one I recalled after years of nightmares. The one I believed to have happened was that I drove off and eventually arrived at the distant toll gate sometime after dawn. What I recalled after time was a memory of two huge landing lights coming straight at me like a truck on my side of the highway but MUCH brighter than the feeble headlights on any 18 wheeler. I recall this too and for those of you who have ever owned a VW bug you will know what I am talking about. There is a method to exiting a VW that is a bit different from most other cars. You put your left hand on the bottom door jam, and from a stiff-arm you roll yourself out of the car. For an instant, you see the ground just outside just before your left foot touches the ground and you finish the roll out the door. What I remember seeing was LONG STRAIGHT SHADOWS FROM THE SAND ON THE SHOULDER OF THE ROAD LEADING TOWARD THE REAR OF MY CAR.

What I remembered is that I had stopped the car to avoid a collision with the oncoming "trucker," pulled onto the shoulder, and turned off the car engine. The thing about the shadows I remember most was the razor sharpness of the edges. Normal tungsten or halogen lights of that time did not make this distinct sharp shadows and that is what I recalled also as being very different. And there was only one shadow, not two so that meant one bright light was in front of the car.

I then recall floating over the grass with my arms in two companions heading for the field to the right of the parked car. The rest is very unclear like looking for something in at sea in an ocean fog. I won't bother with these speculations of what I do not clearly remember but know that I lost time. It wasn't much time, just about an hour, but I lost time. I should have pulled into the toll booth about sunrise but I was there well after dawn. I do not remember everything that happened but I really do not want to either.

So that's the story and that's the truth. Being in the military, I know what planes look like. Having been blessed with high-end ears, I know what helicopters and planes sound like. Being a keen observer, I know the difference between normal and unusual shadows. Being into astronomy since high school, I intimately understand the relationships between the planets, stars, and moon in the night sky. Being a left-brained person, I know what is illogical and logical. This was a close encounter just like many of those similar incidents claimed by countless others. No words were spoken, I have no clear recollection of who stopped me or what their craft looked like, nor do I recall getting back into my car and driving off. The only thing I clearly remember after the encounter is the toll booth and briefly chatting with the attendant.

It took years for me to share this with anyone. I believed initially that I was imagining things but the nightmares continued and I started confiding in my wife. The first friend I told was Burt Cossey as we were waiting to see the Star Wars movie. I told him the tale just before the previews started and before he could respond the preview of "Close Encounters" came on. That blew both of us away and made the telling even more profound.

Today you've read my tale. I hope others who have had similar encounters feel a bit more comfortable with their experience. The universe is just way too big to believe that we are the only ones here. Our intelligence as great as it is feigns terribly against what remains to be understood. Creatures of superior intellect are all around us and some choose to visit like we choose to go to the beach or teens choose to drive the strip on Saturday night. We share much with these visitors in our "nature" and have the same curiosities and adventurous attitude.

Yours for higher fidelity,
Philip Rastocny

My other titles include:

Friday, November 2, 2012

When to Change Tubes

Many of you know that I am a tube fan and own a Dared MC-7P preamp. After performing several rounds of modifications by pulling out ground loops, changing caps, correcting RIAA errors, replacing the volume potentiometer, and swapping out those cheap tubes, I have grown to enjoy the musicality of this preamp despite its modest initial price. It is light, airy, detailed, silent, and dynamic providing clarity and timbre only the finest transistor designs can match.

But being a tube preamp, once I swap out tubes the clock starts running; one day I will need to replace them. But the better question would be: when? NOS tubes take about a week of use to settle in and start to sound the way they will for the next several months (maybe even a bit over a year) and with the price of a good Mullard 12AX7 going from $50-$400 a piece, the timing for replacement can mean the difference between making a wise investment and making a bad decision.

The problem with tube aging is that it is a gradual process and can creep up on you as you become desensitized to its impact. In other words it is sort of like a frog: toss a frog in boiling watter and it will immediately jump out but put it in cool water and slowly bring it to boil and it will die. The fact that you listen to your gear every day makes you not notice these symptoms but one day you will become alerted to their telltale degraded signs.

It is interesting to note that tubes that should be changed may still measure good on a tube tester (so what else is new?). So here are the top 3 hints that let you now from subjective listening when it may be time to swap out those little room heaters (aside from a complete failure meaning that it stopped working entirely).

Pops, tinks, and other weird spontaneous noise. This is the number one reason to change a right now tube. Issues of injected noise or spurious spikes are obvious signs of having to say goodbye to what may be an old and well appreciated friend. Tubes that age to this point can actually be dangerous to the amp and speakers and should be replaced immediately.
Edginess and sibilance. This is a deceptive condition where on the one hand the tube starts to emphasize one region of the audio band you may find appealing but believe me, the tube is on its way out. This is the second most important reason to change a tube since what is hiding behind this symptom can also prove to be disastrous to the rest of your gear. This is usually an indication that for some reason the tube is breaking into spurious oscillation and with time this symptom will only get worse. Do yourself a favor: change it now.
Hiss. When the noise floor starts to creep up causing silent passages to sound like you are listening to music in a wind storm, the tube is going bad. This symptom is the most gradual and can be the least noticeable from all of the rest. Noise can sometimes be discovered on a tester indicating a "weak" tube.

I recently swapped out the two gain stages in my Dared after noticing a sibilance issue and sure enough both tubes were going south. I have been listening to the new ones for about two days now and I can hear them mellowing to that lush full body revealing resonances in sound boards, the character of drum membranes, and nuances in woodwind reeds. Front-to-back imaging at first play took a huge step backwards getting very flat and narrow, but that too is improving as things stabilize.

By next week, things should get back to that pristine sound I enjoy so well. During this time, I will enjoy the transition period since it is much like swapping out a piece of gear with a new one every day. After swapping out tubes, you too will hear this mellowing process evolve. Be patient and allow your new tubes to burn in. Swapping to a new tube always takes time for you to appreciate what it can do to improve your listening pleasure.

There are other reasons you should swap out your tubes (like quality upgrades and other failure modes), but these are my top three reasons once you settle into a tube choice for that component. And a note of advice: when you find a tube that you like, buy spares of that exact same kind. Even new tubes can suffer from infant mortality and last only a few weeks or months. Each time I buy mine, I always "stock up" on what I consider my current selection for the state of the system.

Yours for higher fidelity,
Philip Rastocny

My other titles include:

Thursday, November 1, 2012

DACs...DACs...DACS

It's been a mere 28 years since the introduction of the compact disk and after all of this time one would presume that the bugs have been worked out of the standard. But such is not the case, although it looks like the engineers are getting closer and actually listening to what they are building and at least understanding what the problems are.

Two new advances have appeared that - from the design perspectives - are finally addressing issues surrounding the D-A conversion anti-aliasing filtering issues. The Ayre MP series (see http://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf) describes clearly what one of these issues is regarding phase shift and ringing and what they plan to do about it. The Resonance Labs Invicta (see http://resonessencelabs.com/wp-content/uploads/2012/05/InvictaMeasNotes.pdf) describes another issue regarding head room. Hopefully, I will be able to audition these two units side-by-side at an upcoming audio club meeting and report about their audible differences and contributions.

It's too bad that someone has not incorporated both concerns into one unit, but hey, that's what the high end is all about, right? Progress, not perfection!

Over these 28 years, we have come a long way from the first generation brick-wall anti-aliasing filters designed in the original generation CD players. Moving from fingernails on the blackboard to tolerable sound is a huge advance and one that deserves recognition. Hopefully soon, someone will design an A-A filter that addresses these and other unresolved issues, but I believe the recording sampling rate standard is now the big bottleneck (most agree that 16-44.1 was a mistake). With most artists and studios embracing 24-192 and better standards, one day we should see a new generation of players and software introduced as the state of the art spirals upward.

Until then, I'll still have to spin my old vinyl to hear how far digital has to go.

Yours for higher fidelity,
Philip Rastocny

My other titles include:

Monday, October 15, 2012

How Many Stars?

As one would imagine, observing a UFO is a significant emotional event and one that I personally am re-living over and over. I am a pretty practical, logical, and down-to-earth person who knows intellectually that there are billions of stars in our galaxy alone, each of which are capable of sustaining some form of life. This life may not be what we are familiar with, but regardless EACH of these billions of suns have the potential for sustaining some sort of life. The current estimate for our galaxy (called the Milky Way) is about 300 billion stars, give or take a few billion here and there.

From the sheer numbers of these stars, if say 0.0000001% (one out of 10,000,000) were capable of sustain intelligent life, that means that in the Milky Way alone, there are 30,000 stars in our "neighborhood" that could possibly sustain intelligent life, give or take a few thousand.

Our galaxy is pretty typical spiral-type galaxy meaning that there is a black hole at the center and everything slowly rotates around it like a child's pinwheel toy. Stars are grouped into arms that spiral toward the black hole in something called the central bulge meaning that at the center there are a lot of stars in more than just the galactic plane of the pinwheel. Like a basketball, these stars protrude above and below the galactic plane and the numbers of stars "per square foot" so to speak (stellar density) is much higher there than at the outer edge of the galactic plane. Below is an image from the COBE satellite of what our galaxy looks like from our vantage point.

Our star (the sun or Sol) is about 2/3 of the way out from the center in a pretty uninteresting part of our galaxy. Although there is no way for us to see a top view of this position, the picture below is of a galaxy nearby that we believe to resemble our own and from the arrow you can see roughly where on the pinwheel our sun is located.

There are so many stars, they appear to blur together like a cloud but in reality they are VERY far apart from each other. To give you an idea of how much emptiness there is between these stars, the star closest to our sun is about 4 light years (or about 24 trillion miles) away. Without getting into particle physics, molecules are believed to be made up in a similar way - that is, there is a lot of nothing in between electrons and the protons and neutrons so the really big is sort of an example of the really small.

From edge to edge the Milky Way is about 6x10¹⁷ miles (0.6 million-trillion miles) in diameter; that’s 24,000 times further than the closest star. In other words, it is a very long way from one side of the pinwheel to the other and it takes light a long time to go from edge to edge (about 100,000 years).

So the point is this. There is a lot of distance between us and these 30,000 stars that could possibly sustain intelligent life in the Milky Way and to get from one to another employs a technology available only in the minds of dreamers. How did they do this?

I have given this some thought and it runs a little contrary to current wisdom but is based on what else: sound. The fact that there was no sound (no engine noise or sonic boom) meant that these two UFO did not disturb the atmosphere while passing through. Putting it another way, instead of slicing through the air like the wing of an airplane, these UFOs literally moved through the molecules of the atmosphere without disturbing their position or direction. In essence I believe they were able to pass through a solid wall like a ghost in a cheap Halloween movie.

How they did this is beyond my wildest imagination but I assume that somehow they manipulated the phase of their matter as compared to the phase of our matter thereby guaranteeing their molecules would pass unharmed right through ours. If you are youthful and are intrigued by this, I urge you to apply yourself and consider how something like this would be possible. Just think of what a technology like this could yield in the way of creating a speaker driver!

It will probably take a while for me to calm down and get the image of the UFOs out of my mind so please bear with me while I run off on a tangent to the high end for a while.

Yours for higher fidelity,
Philip Rastocny

My other titles include:

Friday, October 12, 2012

My UFO Sighting

Another hobby of mine is astronomy. I go out with folks and usually spend a good portion of the evening gazing up into the heavens spotting faint fuzzy globs that look more like free floating cotton balls or wispy clouds or a groups of densely-packed stars. I have been hooked on this hobby since my early teens and now have two pretty nice instruments. Last night I was working with the bigger of the two with four other friends and their scopes enjoying the first clear skies we had in quite a while.

As the sky grew dim, we spotted the Space Station floating in the west and sprinting eastward to the horizon. Bright, big, and just a bit faster than a high-altitude airplane, it's white image and unusual shape were seen by all of the members of the group through their binoculars or unaided eyes. It was quite a way to start an evening's observing session. The folding chairs came out and everyone started settling into seeing whatever they wanted to find in the plethora of unique offerings in the heavens.

The rest of the evening was uneventful although the sky cleared, the humidity dropped, and the stars glowed prominently everyone dashing back and forth as one person found an object and another and another. Seeing deep sky objects with your own eyes is much like the difference between reading about how to fly an airplane and actually doing it: it's day and night and where the real thrill is in this hobby.

The night ran short starting at about 6:30PM and by 10:00 two of us were left watching a satellite in the northwest making its way to the east. As it faded from view, I was pointing to where it was disappearing and then my eyes and that of my friend's popped. Both of us gasped and simultaneously said, "What the X*&% is that?" Moving from just west of north and soaring across the night sky to just east of south were two dimly orange glowing bird-like objects silently crossing the blackness.

We both thought they were birds at first but these two UFOs were flying at what we estimated to be about 1,000 to 1,500 feet and traveling REALLY fast. It took less than 10 seconds to fly from horizon to horizon behaving a little like crows in flight moving not in fixed formation but next to each other changing relative positions as if they were playing like those fun-loving black birds with each other.

Burnt orange in color, I noticed that they both emitted their own light but that light was not enhanced from the light coming from the other UFO. In other words, they gave off light but they did not reflect light from another source. It was weird since the two were less than a wing-width of each other as they silently dashed across the sky.

Something flying that fast or that close to the ground should have made some sort of engine noise that we should have easily been able to hear and as fast as they were flying maybe even a sonic boom. Alas, there was nothing for these well-tuned ears to hear, only the low chirping of crickets and the faint rustling of leaves.

My friend was the first to volunteer the phrase UFO and I explained that while I had not seen one before, other groups I had been with over the years had told me of similar sightings of unusual and unexplained objects that were not stars, satellites, airplanes, balloons, and the usually lighter-than-air craft. Taking most of these tales as urban myths or boastfulness from big egos, I dismissed their tall tales as just that - until now. I was dumbfounded at seeing them in flight and there was something about observing such an object after looking into the heavens at galaxies, nebula, planets, and their moons, but this was something I will never forget. It reminds me of what President Jimmy Carter must have felt when he spotted a UFO himself.

So here is what they looked like as best as I can describe them. There were two of them, identical in every way you can imagine. Like a pair of fighter jets, they flew so close to each other it was like watching the Blue Angels performing tricks but these two were traveling much faster than any earthling-created craft ever could. If you have ever seen a seagull float in the air without flapping, this is very much what their shapes appeared to be. Two gently-arching wings the entire length of the fuselage with no aerodynamic characteristic of thin leading edges or trailing edges whatsoever. Bluntly rounded and smooth, the arches folded into a straight like across a somewhat difficult to discern central tube also blunt and cigar-shaped. The orange glow was a burnt tangerine color revealing stripes or bands on the two curved wings providing clues to their depth perspective.

They were huge and unlike anything I have ever seen in pictures or descriptions before. If they were flying at 1,000 feet, they would have been about the length of a 747 commercial jet. They had curved wings like that of a seagulls when not flapping but without the tapered leading edge or trailing edge, nor did the wings tapir to a point at the outer ends farthest away from the fuselage. The fuselage was more cylindrical than cigar shaped but both the nose and tail were also blunt. If the fuselage was 20 feet in diameter, the arched wings were 15 feet thick and ran the entire length of the fuselage, not just a small portion like a conventional aircraft or a bird. The drawing below shows the arched wings uncolored in the front view but they were as orange as the rest of the craft (a limitation of my graphics program).

The gray stripes along the bottom and wrapped around the outer edges. The interesting thing about the orange glow was that the craft appeared to emit light but not reflect light from the other craft.

One added note is this: as we watched the two move across the sky, there were two different personalities behind the steering wheel. One ons "serious" and flew straight never deviating from the course; the other was playful and rocked its wings and moved a little above and below its partner in formation. I could not help but think of how crows play with each other while a flock of them cross the sky where one dives and nips at another. I guess even these pilots had a sense of humor, something to think about.

Yours for higher fidelity,
Philip Rastocny

My other titles include:

Tuesday, October 9, 2012

Subwoofer Tuning

So you buy or build a subwoofer, hook it up to your system, and viola! Deep bass and a lot of it - at least that's what your first impression is. Explosions in films sound more real, punches to the face are chest pounding, and emotionally it is a great addition. Where there once was nothing, not there is something...right? Well, here is where a few simple tools can help you figure out if what your emotions are telling you is what your ears are hearing.

Confirming or denying that what you just added made the change you wanted can take hours of listening during which time you can get more and more satisfied with your system's overall sound. But there is a short cut for doing this that can reduce the time you spend moving the subwoofer around in the room until you find that perfect spot. There are two things you will need to do this:

A smart phone
An MP3 player (most Blu-ray and DVD players will suffice).

First, go to http://archive.org/details/TenMinutesOfWhiteNoisePinkNoiseAndBrownianNoise and download the Pink Noise file. Put this file on a CD, memory stick, or your streaming music resource. This file creates what sounds like inter-station noise on an old FM radio and is a random but uniform signal source spattering the entire audio band. I use the FLAC version since my music streamer plays FLAC files.

Next, spend the $5.50 and download the RTA Pro app for your smart phone from the PLAY STORE or from https://play.google.com/store/apps/details?id=radonsoft.net.rtapro&hl=en. The free version works but the paid version offers far better resolution and is worth every penny. Calibrate your phone according to the instructions in a VERY quiet room.

Now, charge your phone and set it on top of a thin vase positioned in your "sweet spot" at your ear level with the microphone end of the phone aimed at your system. Unplug or turn off all electrical appliances (refrigerator, TV, radio, etc.) making your room as quiet as possible. I do this VERY early in the morning to avoid traffic noises and my wife talking to me.

Turn on the phone, start the app, and play the Pink Noise file. Adjust the volume on your system so that the level is somewhere near -10dBFS. Press STOP on the app and then lightly press START being careful not to jar the phone. You will see now what your playback system is producing in the way of acoustic energy as measured from that particular location in your room. Notice the deep bass level under 200Hz.

I can almost guarantee that the sound pressure will not be uniform. Using this tool, scoot the subwoofer around the room until an optimum location is found. Use movements of inches first, then fractions of inches, and once the right place is found, the sound will be about as uniform as you can get it.

You can try raising and lowering the subwoofer itself if possible to get that last bit of tuning out of it as you can but more than likely you will not be able to raise or lower it - but if you can, give it a shot too.

Lastly, if there are large peaks somewhere, try moving furniture and adding sound absorbing panels on the midlines of the walls of the room or in the corners. This is where sound soak works best and tweak away to your heart's content.

I have used this little technique to do a lot of tweaking in my personal system and the results for a total investment of $6 and a bit of time have yielded extremely satisfying results, at least in the bass and deep bass regions.

Although you could use this setup to position your speakers, I have found that this is not the right way to do that. Using your ears and focusing on the height, width, and depth of the sound stage is more reliable and produces far more satisfying results.

Yours for higher fidelity,
Philip Rastocny

My other titles include:

Wednesday, October 3, 2012

HDMI Cables

Interconnect cables have evolved over the years starting with RCA single-ended, maturing to differential, then optical, and today the various flavors of HDMI. With each advancement came promises of simplicity and assured perfection in connectivity. However as time passed, perfection was not always achieved and the old saying of garbage-in garbage-out held fast.

HDMI cables are a wonderful concept for connecting all video, analog, and network signals from one device to another via digital transmission schemes permitting only ones and zeros to pass between them. The theory is that in a digital signal, there is no way for anything to degrade because of the simplicity of digital technology. Well, that's the theory anyway and for most of you high-end videophiles, you are already aware of the significant differences between so-called perfect HDMI cables.

So what's up with this? In theory it should work but in reality it does not. I own several flavors of HDMI cables all connected to my Samsung 52" 650 series television (which I love BTW and have resisted replacing because of not only its good video quality but its fine built-in DACs). I recently connected a DIRECTV DVR to it since my wife loves football (and she REALLY loves football). So out of the box it came and connecting it with my extra 1-meter BetterCables Silver Serpent HDMI cable we were ready for the NFL.

After turning it on, I immediately noticed a huge edginess and pronounced sibilance region up until that time was not present on any of the other devices already connected to the Samsung. While the video quality was pretty good, the audio quality was terrible. Back to the drawing board.

Hoping that it was a burn-in issue, I tolerated the annoying sssssssssssssssssibilance for about a week and then realized that it was not going away. Swapping the HDMI cable with a Monster M series 1.3a 1-meter version, hoping for the best.

Normally, I do not like Monster Cable products since they have a tendency to color things a bit unnaturally but I had this one lying around and decided to give it a try. The results pleasantly surprised me. While the audio anomaly of sibilance still persisted, instead of it being sssssssssssssssssibilance it changed it to ssssibilance, the best way I can describe it in words. The edginess to the sound is now at least tolerable.

So with this improvement, I decided to start checking the obvious beginning with absolute electrical phase, aka chassis leakage. Results: yes indeed there was a minor issue with the LNB power supply but a quick swapping of the leads on the power transformer resolved that issue. However, the ssssibilance problem persisted and I was left scratching my head again. Eliminating the common problems pointed to the source of the problem as inherent to the design of the DVR.

Additional investigations following my normal troubleshooting steps still uncovered no additional built-in issues I could solve externally. Putting it another way, there was nothing wrong with the system or the way it was connected. Yes, the problem is still there today but I am very tempted to unbutton the lid on the DVR and start poking around. So far, I have resisted doing this willing to try a few more HDMI cables loaned to me by friends and audio-video salons.

For now, we listen to the DVR at low levels so that the fingernails-on-the-blackboard effects of the poorly designed do not make their way to our sensitive ears. If one of you readers could point me to a solution you may have uncovered, I would be eternally grateful.

So folks, this is a plea for help. I hope that at least one of you have solved this problem and are willing to share with others what you did. Until then, I'll be lisssstening to over-the-air signals when critical sound is essential.

Yours for higher fidelity,

Philip Rastocny

My other titles include:

Althea: A Story of Love

Build an Extreme Green Composter

The Extreem Green Guide to Wind Turbines

Build and Extreme Green Hot Water Solar Collector

The Extreme Green Guide to Solar Electricity

The Extreme Green Guide to Improving Mileage

Meditation for Geeks (and other left-brained people)

Build an Extreme Green Raised Bed Garden

Build an Extreme Green Rain Barrel