Wednesday, February 29, 2012

Speaker Driver Evolution?

I am a computer geek, among other things. I jumped on the PC band wagon way back in its infancy and watched as Windows grew out of MS-DOS, straying for about a decade into UNIX and then back again to Windows. Today, my taste in operating systems has changed as has the playing field. My smartphone is Android and my notebook Windows 7. My gigabit network is powered by Cisco and I have 15 devices connected to it, 4 hardwired and 11 wireless. What started out back in the 1970s as a fad is today the backbone of the Internet. It has evolved, as it should.

But such an evolution has not occurred in speaker technology. While there are new piston materials, new magnet materials, new approaches to damping resonances and increase power handling capacity, new surrounds, and new modeling parameters that simplify cabinet design, the speaker driver of choice by the overwhelming majority of manufacturers is still the old dynamic driver.

Components of a Dynamic Speaker Driver

Dynamic drivers have been around since 1924 (invented by General Electric engineers Chester Rice and Edward Kellogg) and have what is called a "linear motor" at its core.

The linear motor, the "engine" behind this type of speaker driver, has been kicked around since 1840 (Charles Wheatstone at King's College, London) with refinements to its design ongoing. The operation of a linear motor used in a dynamic driver is simple. Basically, a coil of wire is suspended inside a magnetic field to which a diaphragm (aka piston) is glued. Applying an electrical signal to the coil moves the piston in and out as the coil tracks the signal back and forth inside the magnetic field.

There are numerous places for error to occur with such a design (flexibility of the glue, non-linear distortion introduced by the surround and spider restricting movement to name just two), and yet we persist in trying to force more from a 90 year old technology.

The main issue is that air is passively pushed by the piston. This is sort of like passing gossip along to friends where eventually the original story is very different from what was first told. Any time you try to push something in a passive manner, there is a non-linear reaction to the push. That is, the air does not instantaneously respond to the movement of the piston because of its inherent flexibility. So even if the characteristic distortions of dynamic driver design could be completely eliminated, the elasticity of the air still produces additional distortions beyond the control of the driver.

The best one can hope to do is to more efficiently couple the air to the piston (use an acoustic matching transformer called a "horn") and keep the piston excursions small so these inherent distortions of dynamic drivers are minimized.

OR, and this is where science is presently stumped, OR find yet another way to move the air that does not require these limitations (somehow eliminate the piston). Diaphragm-less drivers have been bantered about using plasma schemes (aka "flame" or "RF" loudspeakers), that produce amazing clarity while introducing ozone into the air that can harm you after prolonged exposure.

A Plasma Tweeter by Corona Acoustics, GmbH

So we have a way to go in perfecting this technology if what we want to do is to move the air in such a way. Unless we find a brand new way to move air without such inherent limitations, we will be pretty much stuck with the nearly century old dynamic driver.

If there is something to invent, this is it. Hopefully, just as computer operating systems have evolved, so will speaker driver technology.

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:

Tuesday, February 28, 2012

Digital vs. Analog Sound

Last weekend I attended an audio club meeting in the greater Tampa area, It was held at the home of someone who had the ability to play various sources and formats of material (vinyl, CD, SACD, FLAC, etc.) through the same system. The meeting was touted as a shootout between the characteristic sound of these sources intended primarily to see if there were discernible differences between the 24/96 and 24/192 sampling formats. Let's see what happened and what we learned.

After the preliminary demonstrations of the system's capabilities, the meeting snagged several pairs of signal sources playing instantaneously switchable cuts from these two sources. Although not a true double-blind test in the scientific sense of the words, the host did not tell the audience which source they were listening too. I was standing at the very back of the room centered on the two speakers as best I could and forward about ten feet from the rear wall. The rest of the serious listeners were huddled at the sweet spot.

We were listening to Dire Straights: Brothers in Arms, a personal favorite, and the psycho-acoustic position of Mark Knopfler's guitar shifted wildly as the signal sources flipped here and there. All others were focused on tonality and nuances but on this particular system such distinctions were extremely difficult to hear and equally inconsistent in identification. After trying to hear such imperceptible changes, I observed something others had ignored.

To me, there was no challenge in being able to consistently hear the differences as demonstrated by the dramatically changing size of the sound stage. And once I pointed out this shift, others joined in on finding similar consistently changing clues all hinged on this fact.

Ignoring any colorations or limitations imposed by an link in the playback chain, what was confirmed was that the vinyl source produced the widest sound stage with the guitar extending at least six feet beyond the outside of the right speaker. The 24/192 source collapsed the stage to about 2 feet outside of the speakers and the 24/96 source collapsed it again to about a foot inside of the speakers, something no one was ready for.

Several rounds of changes were also evaluated and all sounded roughly the same with certain distinctions here and there, none of which anyone could really agree upon with any consistency. Why was this?

The playback system did have a characteristic limitation, one that I presume also limited us in being unable to note other differences: sound stage depth.  Front-to-back depth is a signature of a high quality playback system where the extreme rear corners are where details on the finest systems hide. This particular system struggled in this area and more than likely concealed other distinctions.

The moral of the story is this: when there are very few noticeable differences in signal sources played through your system, there is something else wrong in the playback chain. There is a built-in issue that prevents one from hearing such differences because such differences in signal sources are obviously there. If one cannot hear them, there is an undiscovered factor masking the sound.

So in pursuit of perfect sound, digital or otherwise, you need to get your "ducks in a row" so to speak. Identifying which particular piece of equipment is the weak link can be a challenge. Typically when one thing changes, it introduces an audible alteration; however, that's really starting at the middle and trying to solve a problem before verifying other assumptions you have made about your system are indeed correct.

While some view this as a tedious and unnecessary process, I prefer always to start at the beginning. I start at the place where electrical power enters the home and work my way forward from there. Once I am certain this issue is correct, I move on to the next and so on. In this way, I methodically analyze the problem and assume nothing is correct from the start.

When you are ready to troubleshoot your system, you may be tempted to jump into the middle. While this often is successful in changing the sound, there may be other issues hiding behind your assumptions that are truly the weakest link in the chain.

My advice is this: Be methodical and be consistent. Every piece of gear in your system may be operating perfectly and need not be replaced. Finding the source of issues that allow the music to come through is part of the fun of this fascinating hobby.

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:

Monday, February 27, 2012

Your Ears and Your Speakers

Cones, domes, ribbons, leafs, ring, and at one time ionic tweeters are speaker drivers used in attempts at filling in the last few (top) octaves of sound human ears can hear. Each driver manufacturer claims that their technology is the "best" and so it seems that it is.  Some sound better off-axis (listening from the side instead of the front of a speaker), others have very low rise times (giddy up and go like an Olympic 100 meter sprinter vs. a Sumo wrestler), and still others have very low settling times (when the music is over, the tweeter stops equally as abruptly without continuing to wag like the tail of a dog). Each characteristic has its own sonic attribute. But how high and exactly what can the human ear detect? What are the limits of hearing all of this otherwise sales hype? Can a human being actually detect such advances or is this technology only measurable by laboratory instruments? What is the truth behind these so claimed technologies?
Most humans hear less and less high frequency sounds as time marches on (a kind way of saying as we get older, we go deaf). I remember as a youth walking into a room with a television on and hearing a dreaded high frequency whine. This happened to be the noise an old-technology fly-back transformer made which was 15,750 Hz, so my hearing at that age was at least that high. I also remember telling myself that "I could not wait for the day I would no longer hear this annoyance" and one day it did come. To tell you the truth, I miss it.
My hearing loss was a gradual process and one hastened by my selected profession. I was an aircraft flight line mechanic while in the USAF and I ran a chain saw for a year cutting down the forest for my driveway in Colorado. Gradually, the sweet tinkles faded like a beautiful sunset over the ocean. Or did they?
Hearing the actual upper frequency limit and detecting the effects of increased bandwidth are two totally different issues. Once you hear the difference between the two and understand how your brain interprets this information, you can "hear" beyond your physically-imposed limit (you can detect ultra-sonics without actually hearing them).
What the ear-brain understands well is how fast something happens, especially binaurally. This is how we know what direction a sound is coming from. It is this sense of speed or timing that is a factor in bandwidth; you may not be able to hear what a dog hears but if the fundamental note is within your discernible range, you can hear the difference between say a 10KHz bandwidth and a 20KHz bandwidth tweeter.
Just as you can "feel" bass (sub-sonics), say when going into a large church and listening to a 32-foot pipe organ, the information you detect is beyond what you can hear. What you detect is a vibration in your seat or movement of the air on your skin and that is processed by your brain as sonic information.
Adding these sub-sonics and ultra-sonics to your system therefore enhances the experience. I am about to add a super tweeter to my system. What I expect is that in doing so, when properly phased, it will also enhance the bass. Why? Harmonics! There is missing information our brain needs to reconstruct from what the electrical signal in the rest of your gear is trying to tell it.
So we are back to the weakest-link-in-the-chain concept of high fidelity where your stereo can only sound as good as the worst component (the weak link). Your ears, regardless of how high you can hear, are not the weakest link in your playback system although your ability to hear everything your system is capable of recreating does diminish with age (and the number of rock concerts you attended). If your dome tweeters can only reproduce sound to 15KHz, they will have one characteristic sound while those fancy ribbon tweeters that can reproduce sound to 40KHz will have another.
It is best to not limit the information available at the speakers (that is, do not make the speakers the weakest link in the chain) even if the rest of your system cannot reproduce it. A common phrase bantered about today is "what is your stretch?" meaning what are you going to do that taxes your believed limitations? Do yourself a favor and take your system up a notch (stretch it) by adding sub-sonic and ultra-sonic information your ear cannot hear. Audition quality speakers with outrageous bandwidths and see if you can hear the difference. Who knows...they may find their way into your listening room sooner than you think.

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:

Friday, February 24, 2012

The HiFi Car Stereo Oxymoron

Oxymoron: a figure of speech that combines contradictory terms.

Threre are a few classic oxymorons I can think of off of the top of my head. Some of these make sense when you think about them but literally they are direct opposites.  For example:
  • The same difference
  • Old news
  • Holy war
The list goes on and on and a few would even add the Central Intelligence Agency.  My next nominee is Car Hi-Fi.

Yesterday I bought a brand new car whose name shall remain anonymous since all new cars pretty much without exception, fall into this category. I understand that there are a few esoteric exceptions, but regardless the VAST MAJORITY of automobiles have total junk equipment they dare to categorize as automotive high fidelity. Again we are presented with the dilemma of economics and audience.

Marketeers know that the best place to fish for cash is in the mass market. Thanks to Apple and their wildly successful i-whatever product line, the masses are thrilled to background noise in non-musical accuracy. I have grown to accept this nonsense and even installed an i-Pod in my old 07 Yaris attached to my Pioneer AVIC-D3. Yes, it was elevator music and yes it was terrible, but the road noise of the old Yaris drowned out any hopes to hear high fidelity.

Enter the new car. This is the first time I have ever purchased a non-high-mileage vehicle in my life. I did so for the space and the ability to tow a trailer so after comparing the minuscule mileage differences in this class of car I selected one specific American made SUV. I also felt hugely supportive for our struggling economy in doing so, something that money in this case actually can buy. During the test drive, I was focused on the location of controls, the temperature of the A/C, how much wider the vehicle was than the Yarius, and items like that. Satisfied with the deal, I drove off the lot.

But then it came time to listen to some music, so I turned on the FM radio. ARGH! What the heck was that? The built-in unit had such bass over emphasis that the system sounded like one of those imports rolling up next to you at a stoplight those boom box literally shakes your car windows. I was appalled and realized that this was the mass market. What the heck have we trained our children to listen to?

Every channel was the same, even NPR. Unfortunately, the radio design is integrated into the system display so there is no chance of ever getting out from under the radio's terrible sound (did I mention a bandwidth all the way up to about 5KHz?). What the heck to do. I've driven off of the lot, and now I am literally stuck with a unit that occupies the space of the stereo and I cannot swap it out because of the integration with the other car's systems. Shucks!

After a few miles, I decided to turn into Radio Shack and reconnect the old i-Pod (it has a USB port for the radio but there was no cable provided despite this car's upper $20,000 price range). I was getting tired of all of the nonsense commercials anyway and the thumping bass would just not go away despite the fact that the equalizer was set at -6 (it was +10 when I jumped in as was the treble setting; obviously someone from the mass market was listening to it before I sat in it).

Well, in a word, I was relieved to know that the FM radio circuit was the culprit and that the i-Pod actually sounded pretty good, much better than in the Yaris rig. But what the heck was that boomy bass? The only thing I can figure out is that the marketing folks know that the mass WANTS IT so they give it to them. But what about us lunatic fringe folks who actually know what music sounds like? We have to take a back seat here and just tolerate the junk that marketing tosses at us.

So much for the benefits of boundless free enterprise. Seems to be an oxymoron in there somewhere.

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:

Wednesday, February 22, 2012

The Top Ten Assumptions Every Audiophile Makes

Let's see here...let's ask a better question. How many assumptions do you make every time you flip the switch on your stereo? Let's start at the very beginning and see.
  1. You assume that when you turn on the switch to your stereo, there will be proper electrical power already already going into your home (here proper means just enough electrical voltage and current to operate your equipment, not the quality of that power).
  2. You assume that this power is not diminished between the utility meter, the breaker box, the wall wiring, and finally the outlet into which your stereo is plugged. So whatever power is coming into the house is also available at the wall outlet.
  3. You assume that all of your equipment is properly configured from the factory to perform at its highest possible level. Every piece of equipment is tested and wired so that it produces the least amount of electrical interference to anything else connected to it.
  4. You assume that you yourself have not built into the electrical and mechanical connections between all of the components in your stereo any issues that could compromise the sound. All of the equipment has adequate power provided to it and that there are no hidden :"gotchas" influencing the power.
  5. You assume that your line conditioners, interconnect cables, network connections, and speaker wires are all as good as they can be. You have selected each of these based on personal evaluations and that in the process of your selection the cables themselves have not introduced any issues.
  6. You assume that the position of the speakers and equipment in your listening room are optimally configured so as to least interfere with each other. You have taken pains to move your speakers into such a location that it optimally performs in that location and that the location of the equipment in your system does not interfere with this placement.
  7. You assume that the furnishings in the listening room are of such that also do not diminish the sound but are rather strategically placed to improve rather than detract from the best sound possible. You have located furnishing away from the speakers and at the opposite end f the room.
  8. You assume that the source material you are listening to has been recorded uses the highest quality equipment and the highest possible standards to capture the sound as accurately as possible. You have found several pieces that you are satisfied with or have used recommendations of other experts.
  9. You assume that the electronics in your system are capable of faithfully reproducing these signals without significantly altering their content. You have chosen and interchanged equipment is such a way that all pieces perform harmoniously.
  10. You assume that you can hear the difference between accurate sound and whatever music is coming from your system. You have a favorite group of instruments and know exactly what they sound like in real life. Your ears are not full of wax and you are not deaf.
Wow! There are a lot of assumptions you've made, or if you haven't you now know that you have. There are more but these are the top ten.

The next series will investigate what these issues are and what you can do about them. Until tomorrow, think about what these really mean to you and how it impacts your system.

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:

Tuesday, February 21, 2012

My dad can beat up your dad...

Early on in this hobby of audiophilia, I learned a very valuable lesson I wish to share in hopes that many of you can learn from my mistakes.  I was going to Oklahoma State University at the time and the guys in the electrical engineering program were all pretty close. We studied together, shared stories together, worked in labs together and shared our strange attraction to the love of a certain field with each other. Much like a fraternity or sorority, bonds of friendship grew that continued long past graduation.

In college, several of us struggled financially, myself included, and although our love for that particular field was intense and a high priority in our lives, there was only so many funds that could be dedicated to that love. After all, we had to eat, pay the rent, buy books, tuition, gas, you know, the usual stuff all college students struggle with to keep their heads above water. It was no different for me and Henry.

Right next to the picture in my wallet of my wife was a picture of my stereo, yes, my stereo. Although a color Polaroid (for those of you who do not know, Polaroids were the early instant gratification photographs that allowed you to see a picture about 30 seconds after it was taken), this well worn photo was shared with each of these friends and they also shared similar Polaroids of thier HAM rigs, Tesla coils, mixing consoles, and the like. Henry also shared a picture of his stereo and we found an instant kindridship

One day, I went over to Henry's house with a few friends to audition his rig. I don't even recall what his system was but here is where my life lesson came. At the time, I had a McIntosh MC2100 and MX110 tuner preamp with AR5 speakers. Henry, less financially fluid, had something else, let's say hypothetically a Garrard turntable, KLH speakers, and a Sausui tube receiver. I truthfully do not recall but that is not important.

Henry was very proud of what he had managed to assemble, deomnstrated it with bliss in his eyes, and we listened to numerous cuts of his favorite pressings. Then came the question, one that you typically hear audiophiles ask of folks with similar interests, "So what do you think?  How does it sound?" This is where I put my foot in my mouth. This is the moment that if I could I would choose to do over again differently I would. Again, I do not recall my exact words, and again that is not important.

I replied immediately in as honest of a tone of voice as I could muster up and said, "I think it sucks." Althougn I said this in a half-joking manner, in my knee-jerk unthinking response, I crushed a friend, and in a single moment I lost a relationship that should have lasted decades. With brutal honesty, I engaged my mouth and then my brain. I was a jerk, a complete idiot, and I did not even realize it. My utter insensitivity to the situation caused me to lose a good friend and I have regretted that moment for its results but I am also thankful for that moment since it changed me for the better.

I was oblivious to the damage I had just caused to our friendship and left Henry's house completely unaware of my idiotic egotistic answer. Henry shyed away from me from that moment on and I did not, at that time, understand why. When I would walk into our study group, Henry found an excuse to leave. When I arrived in class, Henry turned away and started talking with others so he would not have to talk to me. It was a behavior I had never encountered and just swept it under the rug.

One day, long after I had graduated and moved to Denver, another classmate called me and told me that Henry also lived in Denver.  I was shocked but glad to hear this. Henry and this other classmate were very good friends I wanted to take the opportunity to try to reconnect. This other classmate told me about what I had done that fatal day that crushed Henry's spirits. I was only slightly more mature then than I was at the time of the tragedy, but still a complete amateur at being right-brained person.

I called Henry and we chatted. I thought to myself, "This time, I am going to praise his system regardless of what it was." I did and missed the opportunity to get past the symptom and down to the problem. I did not tell him what I felt, but rather what I thought. I believed at that time it was my words that caused Henry pain and it was not; it was my attitude. In the conversation, no matter how I tried to be someone else, my attitude still prevailed and it was this ingrained part of me that caused the split.

That was in the late 1970s and I have not heard from Henry since. The story itself is sad but its telling I hope touches the hearts of some of you out there who suffer from similar insensitivity and are completely unaware of your attitude. Here is the bottom line: if you want friends and quality relationships, when you get ready to point a finger, look at how many are pointing at that person and look at how many are pointing back at you (4:1, hmmm...that should tell you something). When you are telling someone in all honesty about what is "wrong" with something or someone for that matter, what you are really saying is what is wrong with yourself.

Take time to evaluate your attitude own and think about what you want the outcome of your words to be. It is easy to say whatever comes to mind and I am not encouraging you to lie, in fact it is always bet to express your feelings and doing so keeps you emotionally healthy. Another firend recommended this technique and I encourage you to consider it also: when asked, take a moment to respond and ask yourself this question, "What do I want my outcome to be?"

There are many ways to say the same thing. All I am encouraging you to do is to get over the infentile attitude of "My dad can whip your dad" and get more mature. Honesty is always the best policy but temper it with kindness. A person's stereo cans till suck, you just do not have to be that brutally honest in your response. Count to five, stroke your chin, and think about what it is that you want your outcome to be. What is five seconds out of your life if it saves a relationship?

Henry, if you ever read this, I am sorry for my juvenile insensitivity and apologize for what I did. I was too young to see how what I said did what it did. I was wrong. I hope you have had countless hours of listening pleasure on your system and hope that you can forgive me.

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:

Sunday, February 19, 2012

Your Stereo's Missing Component

So you've swapped this for that, tweaked here and there, compared A to B, and after listening to live music up close, your rig is - well you're still not happy with it. There is something wrong and nothing seems to help. No amount of money gets your system to sound like the real thing.

Yet, going to a friend's home, you hear the speakers literally disappear, transformed as if by the audiophile gods into producing a sound stage so three-dimensional that you can close your eyes and visualize performers walking up to microphones, hear sheet music turning on a stand, and almost make out the shape of the small recording studio in which the musician was playing. What's up with that? What does this system have that yours does not?

All high-end loudspeaker manufacturers use computer aided programs to minimize resonances within the cabinets carefully calculating dimensions and placing speaker drivers in such a way as to minimize reflections and resulting interactions. Incredible pains are taken to recess driver frames and smooth surfaces so that the first reflections - the closest surface capable of producing an echo that could reflect back to the source - are reduced to the point where their effects are controlled if not completely eliminated. But yet these manufacturers are unable to control the other speaker box that has identical and complicated resonances and another whole set of first reflections: your listening room.

Yes, my friend, the room in which you place your speakers is literally another speaker box, one in which the other must operate. The constraints you place on your speakers is predefined by the shape, size, and contents of the room. Take for example theaters and music halls. Here, acoustical engineers take the time to minimize these nasty acoustic interference patterns so that the audience can appreciate what the singers and musicians are trying to produce. The greatest concert halls in the world are rectangular in shape with the stage along the short wall of the room. Why do you think this is and what can you learn from their experience?

Avery Fisher Hall, Home of the New York Philharmonic

See the panels at the back of the stage in the above photo of Avery Fisher Hall? Why do you think they are there? What about the strange shapes on the left and right walls, what are they doing? And then the ceiling has these weird contours and symmetrical patters so they too must be part of the plan, right? Right indeed.

Nothing in a truly great concert hall is done by accident. Every square inch of its design is conceived, reviewed, tested, and adjusted based on listening tests and adjusted accordingly. The best ears in the world come to hear performances from the finest musicians and voices at such places and such people are far less forgiving for mediocrity.

Of course you can always hire a similar engineer to come out and treat your listening room, and you may need to after trying these next three tips. But there are a few things you can do to help improve the sound of your room so that the sound of your system is enhanced.

Tip Number 1: tame the first reflection. All audiophile listening rooms have a "sweet spot," a point where the sound is best heard. At this position, moving just a little in any direction, left/right, front/back, up/down, drastically changes the sound and therefore its appreciation. From this place, have a friend move a flat mirror along the left wall until you see the left speaker and then until you see the right. Mark these two places with painter's tape. Do the same on the right wall, ceiling, and floor. Now you have identified where you must place sound absorbing materials so that the reflected sound does not interfere with the direct sound. Hang tapestries, rugs, or acoustic panels at these points.

Wall Rug Absorbing First Reflection

Tip Number 2: use the Live End/Dead End room concept. This approach in listening room treatment encourages reflections from the non-speaker half of the room and discourages reflections in the speaker half of the room. Here all walls, floors, and ceiling are somehow treated so that all reflections are reduced or eliminated. Much like the acoustic panels at the back of the Avery Fisher stage, absorbing all reflections along this wall helps to improve the sound coming from your speakers. Treat whatever you can while still maintaining reasonable aesthetics (that nasty compromise).

Wall Tapestry Adding to Dead End Concept

Tip Number 3: deaden the rear of the speaker.If you do not own dipole speakers (those intended to radiate from the front and rear of the design), you can tape a small amount of sound absorbing material to the back of the speaker. This reduces the first reflections caused by the sound wrapping around the speaker cabinet and reflecting off of the speaker wires, terminals, and whatever hides behind.

Sound Pad on Rear of Speaker

Try these three tips and see if the sound of your system improves. Remember that the shape of the room is already fixed so unless you move your system to another room, you have little other choice than to try to make this room compliment the sound produced by the speakers.

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:

Saturday, February 18, 2012

Tube Dampers

I have a Dared MC-7P preamp presently in my rig and out of the box, it was a decent but not particularly spectacular sounding piece of gear. There were a few annoying things about this particular piece of equipment that just made it fall short of being a really great little no nonsense preamp. In my investigations (I love taking off the cover off of such equipment and pouring over the PC board - I think this is fun and describes part of my inbred geekdom), I discovered that in some cases well accepted design concepts were used. However, there were a few things, like ground loops - the topic of several other blogs - that stunted its potential.

Fast forward beyond the post-surgery trace cuts and elimination of wiring redundancies, this preamp really started to sound decent. After additional tube swaps, the clarity and detail came alive and proved to me once again that an idea conceived in the R&D lab was not properly implemented by the production team. It is unfortunate that these two worlds are so far apart since the things I did to transform this gear - especially removing the ground loops - cost little if nothing to implement AND transforms how this particular piece of equipment could be priced. To me, that's like leaving money on the table in a sale and something that seems to be fundamentally wrong with high end manufacturers, Chinese made or otherwise.

So after proper tube burn in (this took a mere two weeks), one day the tonality and balance snapped to attention as if a new piece of equipment was suddenly in place. I was elated to the sound since my particular biases are in timbre and body resonances of acoustic instruments. It seems that the vast majority of loudspeaker and equipment designs ignore this all important property and on that day (let's call it B-day for short), on B-day, tears literally dripped from the corners of my eyes. I was entranced as was my wife who too heard this remarkable transformation.

Well, you get the picture that something happened and everything just settled in. I had been emailing someone who contacted me encouraging him to attempt this same modification (a free PDF document of what I did is available if you just send me your email address in a request). Long story short, he achieved similar results so much so that out of gratitude, he sent me some tube dampers.

As you may already know, everything resonates at some frequency; everything resonates. Some resonances appear within the audio band and when this happens, it is a NASTY thing.  But others when they appear out of the audio band can still impact sound quality as infrasonic and ultrasonic vibrations. On B-day, it seemed that this little preamp could not get any better. It was dynamic, detailed, quiet, and most important of all if you've been reading any of this blog, musical. After B-day, things sounded so much more realistic, playing music with which I was intimately familiar sounded like a whole new performance, there was that big of a change. On B-day I had not, however, addressed the resonances in the tubes, and one that I feared one day would need attention.

Last Friday morning, as I was finalizing my tax information, a delightful surprise appeared in my mailbox, completely unannounced. This same person - out of the kindness of his heart - sent me two pair of Levey Tubes' dampers. It was almost as if he were clairvoyant and could somehow hear my system across the miles in the frigid white north of Minnesota. Without delay, I powered down the Dared and slid them onto the rectifier (a Sylvania 5U4G) and driver (an RCA 6V6GT) tubes. What happened next took a while for me to sort out.

Tubes get hot - very hot - and when touching them with oily hands or putting something on like tube dampers, there will be a period of time when the odors that waft into the listening room become rather unpleasant and even obnoxious. Such was the case where, although the odor was not entirely unappealing, it was indeed foreign and invasive, annoying if nothing else. Struggling through this burn-in period may be much different than that of the B-day tube burn in since in that time period my nose, eyes, and throat were not inconvenienced. But I will persist and persevere after hearing what I am about to say.

In a word, they worked! So what happened? Go up to your speakers and briskly rap the side with your knuckles. What you hear is the natural resonance of the speaker cabinet.  Rasonances are unavoidable since everything resonates, tubes included. To further deomnstrate this to yourself, play something at a reasonable sound level and put your hand flat against the wall midway against its length and height (if on a stud, move 6" left or right). You will notice that the wall itself moves gently underneath your hand in response to the sounds created by your stereo. This is the natural resonance of the wall and it too is unavoidable. The resonances you feel under your hand may be excited at different tones so this natural resonance can occur at more than one frequency. So it is with the glass envelope that surrounds every tube.

As the sound level increases, so does the intensity of this resonance. During loud passages, you can imagine the glass in the tubes wiggling in and out just as the sheet rock did underneath the flat of your hand. These gyrations occur in the floor, walls, and ceiling along with anything else in your listening room (ever heard a window pane resonate, or wine glasses buzz on a glass shelf, or a picture rattle on the wall?). So it is with the glass envelope of a tube - it resonates.

Fortunately, resonances can be treated. In listening rooms, tapestries, sound absorption panels, and rugs can help tame those annoying little buzzes that interfere with what the acoustic information your speakers are trying to convey. Such buzzes and resonances are often at such a low level and so familiar that they are ignored by the ear-brain biological mechanism and disregarded as nonsense noise. BUT it is during this neural-processing step wherein the attempts to eliminate these annoyances, also loses other acoustic information.  Much like turning a tone control up or down to compensate for speaker driver inadequacies, resonances too transform what cold be into something that is just plain nasty.

The tube dampers tame resonances in the glass envelope of a tube. If you gently tap a tube with a small piece of metal like a ring on your finger, you will hear a tiny clink or tink. This sound is the natural resonance of the glass envelope. Combined with the mechanical coupling to the rod-mounted pieces inside the tube, these tiny mechanical resonances are added to the electrical signal inside the tube much like the Doppler effect changes the pitch of a car as it approaches.  One would think that such minute resonances would be imperceptible however that is not the case. Because of the gain the rest of the stereo creates, these mechanical resonances are in effect fed back into the low-level amplification stage and thus re-amplified and the resulting distortions re-amplified again and again.

If you have ever driven in a car with a tire out of balance, you know that there is a certain speed at which the tire wobbles wildly and at other speeds it seems to be just fine. But once the tire is balances properly, you feel the total impact of how this imbalance affected the feel of the car at all speeds. You realize that although not resonating wildly, it indeed changed more than this single resonance point and only until it was gone did this effect become obvious at all speeds. So it is with tube dampers and other resonance removing products.

What I heard was much like a vacuum cleaner sucking out the garbage from in between notes. Individual resonances in strings became more defined and echoes faded away in a smoother, more natural way. The best way to describe the effects is as if I were listening to the quality of the master mix itself placing the entire playback system in the recording booth, the transformation was this complete. Even watching movies, the soundtracks are tranformed into delightful melodies that even seem to improve the visual images. Impossible, yes, but the tiny distractions of these minute resonances once removed permitted my brain to be less busy process out junk information and enjoying everything else more.

So now, the level of my acoustic enjoyment has shifted once again as I hear more things from unfamiliar source material. Once identified, I hear these same revelations in all source material improving the overall quality and enjoyability of everything I play.

So the lesson is clear: do what you can to tame resonances. Take this lesson and apply it not only to your tubes, but also to the rest of your listening room, as will be the subject of the next blog.

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.

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Thursday, February 16, 2012


As I write, the flute, oboe, viol and bassoon of Couperin serenade me on a piece from the Pandora music channel I had never heard. Sometimes I feel like there just is not enough time to hear all of the things I want to hear from the plethora of performers in the world. It's nice to listen to my select favorites but when a random mix of lesser-known artists and even more rare performances of well known ones, I can truly begin to appreciate the amount of true genius that has graced this earth. The way each instrument enhances the other, the timing, the intensity, the interpretation, it all is so magical to me.

I've been writing professionally from my first formal position out of college, a service manual for an electronic scalpel. I have a reasonable vocabulary and yet the numbers and meanings of adjectives in the English language from which to choose is rather limiting.  Reviewers struggle to describe nuances comparing sonics to random non-musical occurrences and esoteric synonyms from everywhere to help describe those emotions realized in listening to something new, something really different.

Words fail me at times when I hear something done right. For example, the ambiance and echo captured during the recording to me is as important as the actual technical execution, and when properly revealed by the playback system introduced an emotion that help you get an insight to what the musician was thinking and feeling at the time. I can only imagine what different levels of appreciation musicians and conductors have that I still must learn to understand. But I do know that as I listen to more and more variety, I gleam further insight to these undiscovered pieces of this grand audio puzzle.

As the level of my playback system became sufficiently refined, there was a point where a distinct turn was made from reproducing sound to recreating segments of reality. This extreme level of refinement came after carefully listening and thinking about what was right, and what was wrong. One friend recently stated that the front end was as good as it gets and now I had to focus on the extremes (he meant the extreme lows and the extreme highs the system struggled to reproduce). While true, limiting the bandwidth allows me to hear more of the content in that limited region and for this I am grateful. I am grateful that the bass is not earth shattering and the highs are not ear piercing. I am grateful that what is left is - in a word - right. For now, instead of listening to the equipment, I can listen to the performance.

One day in our Conifer home, I had connected a function generator to my system and was sweeping a band at the low crossover point (638Hz). I was trying to address a dip in that region where I believed I could address by hand selecting various capacitors, resistors, and inductors in just the right proportion. The near-field calibrated microphone, headphones, real-time-analyzer, and function generator were all piled in front of the speaker as was my notebook and soldering gun. I was listening to how the minute changes in components impacted the sweep either improving or degrading the sound. After about 30 minutes (Althea is a true sonic angel), my wife came down from upstairs and said one word to me, ENOUGH, and turned around and walked back upstairs.

In that moment, I realized what an obsession I had in getting it "right." What I was focused on was something even I had a hard time hearing consistently and her point was well made. I immediately stopped what I was doing and never went back again, at least not on this speaker. There comes a time when an audiophile's obsession with quality becomes an addiction, and I had crossed that threshold, It was a moment I would be eternally grateful for in all of the coming years. That was the summer of 1989, a mere 23 years ago.

Today, I enjoy listening and understanding music and sound, especially from those cryptic messages reviewers convey in their columns, but combined with the wisdom imparted by a chance encounter with a conductor. The variety of things discussed and the attention to detail these well-trained critic's ears embrace is truly remarkable. One day, I went to listen to the Nashville Symphony back when Maestro Kenneth Schermerhorn held the baton. In a meeting with the audience before the performance (sort of like batting practice for classical performers), Maestro Schermerhorn described withs similar enthusiasm but greater passion than these critics the sound of the orchestra he planned to produce and the techniques he intended to use to do so. I was immediately thrust into another level of music appreciation, one that if I had not taken the time to consider would have been missed.

The point is this: there is always something to learn and one way to find variety is to, as Monty Python's Flying Circus routinely professed, do something different.  By putting variety into your acoustic life, you can feast from different culinary masterpieces and enjoy more musical emotion than by focusing on your present acoustic addiction. Variety is truly the spice of life. Sample yours today.

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: