The troika of Helmholtz resonators occupying a prominent position at the business end of my aural illusion engine.

The Listening room... the final component!

As all good Audio Geeks know, the listening room is the final and most-overlooked component. With my recent marriage and the subsequent combination of my home with my new bride's in Elkhart, IN, came the required taming of yet another room in my pursuit of listening. The new room is much smaller than I am accustomed to and after two months or so of traditional taming techniques—including LEDE (Live End, Dead End) room treatment and Michael Greene Corner- and Echo-Tunes™—I was still convinced more truth could be wrung from the system: if I could somehow further remove the room from the equation. That is when I remembered a Do-It-Yourself project I had seen and pondered in early 1999 by Jon Riesh. The Helmholtz Resonator project he described, based on a well-respected $1200 retail product, had just not seemed complete to me. Back then, I had started to put together my own D.I.Y. concept, but I had never really followed through on it. Hmmm. It looked like it was time for a mission to the local building supply store and a D.I.Y. weekend!
 

Your mission, Mr. Briggs… should you decide to accept it

Knowing what I was going to have to bring home, it was apparent that my S-Class Mercedes sedan would not be the right choice of vehicle for this jaunt. One of my oldest and best friends, "Tin Ear" Bob, lived some 20 miles away. Since I enjoy his company—and he owns an SUV—I decided that I should get him involved in this escapade. After vaguely explaining the purpose of our foray, Tin Ear was a willing participant in the ensuing treasure hunt that was to bring an even higher level of sonic nirvana to my listening room.

Arriving at the local Lowe's and only briefly outlining our task, the first thing I did was grab a cart. That gave Tin Ear a start. He isn't used to seeing me fetching more than I can carry on one of my Musical Meddling missions. Normally, I'm on a quest for small things, easily carried. Wearing the most disconcerted look I had seen from him in some time, I started toward the plumbing aisle.

Not finding exactly what I was looking for, at least in the exact dimensions I was after, Tin Ear suggested that I question the helpful associate. The young man quite indignantly informed me that the PVC pipe size I was looking for, one with a 2.5" inside diameter (ID), was not a common size. The 60" length I required was no problem and was in fact quite standard. However, I would have to settle for either a 2" or 3" ID. Doing some quick mental gymnastics, since neither of us had brought a calculator, I settled on the 3" variety in the 5-foot standard lengths. I needed nine for this project, and at $4.35 each, they were a bit more than I had hoped for. The 2" ID pipes were under $3, but I didn't' think they wouldn't serve my purpose as well. Still, $39.15 for the lot was a small price to pay for the performance enhancement I expected. Into the cart they went, all nine angling up and out the front of the cart. As we headed for our next acquisition, we looked like as if we were pushing an underground-terrorist's homemade, multiple-rocket launch platform on wheels.

Next, I needed some lumber. I found a 48" long by 10.5" wide pine plank that was 1" thick. Not that it had crossed my mind or mattered that much to my purpose, but it had a nicely routered surface on one of the facing long edges; its intended use was for a step. This was perfect—it would yield three 16" long bases for my venture. The sticker said $9.97. After wedging the plank into the cart, it was time to head for the checkouts and move on to our next stop.

Though nearly picked off by a careening Toyota in the parking lot, we successfully loaded our precious cargo into the back of the SUV and were en route to Wal-Mart. First, the sewing section for a 20-ounce bag of polyfil, tagged at $1.64. This is the stuff you use to stuff (sorry!) pillows or cushions. Or, if you have an IASCA background, what you use to loosely fill subwoofer cabinets. Next, the sporting goods isle for two packages of 5/16" threaded 125-grain archery field points—for base spikes—at a whopping $1.99 each. Heading for our last selection took us past Hardware, where I snagged two packages of 1.5" black, pan-head wood screws at $.98 a pack. Finally, a saunter down the paint isle for three 11-ounce cans of black gloss spray paint at $.98 a pop. Feel free to express your aesthetic inclinations here, but remember, the fruit of your labor will occupy highly visible positions in your listening room and you'll likely be looking at them for a loooooong time! By now, Tin Ear was really confused, to the point of openly scratching his chin.
 

Assembling the goods

Once home, Tin Ear graciously helped me unload our treasures. Then, offering some lame excuse about having something else to do, he disappeared into the evening. Oh well, his loss. I measured the plank and cut it into three 16" lengths. I needed three 3.5" round holes (as that was the outside diameter of my PVC pipes) cut into the bases. My concern was that I wanted them to be unevenly spaced across the length of the board, yet have the group of three centered along its width. Some quick calculations told me I could have 1" of space between pipes number one and two, 1.5" of space between pipes number two and three and still have exactly 1.5" on each end.

After marking a centerline running the length of the 16" base and subsequently marking the exact center for the three holes, my trusty Milwaukee hole-saw neatly did its job chewing out the three required perfectly round holes. Now, if you should happen to have a drill press available, use it. The idea is to get the holes drilled perfectly perpendicular to the surface of the plank so that the pipes stand up straight and parallel to each other. If you must do it by hand, take your time. Keep the drill as close to perpendicular to the surface of the plank as possible.

Next, I had to drill the holes for the spikes. You can use wooden spacers (either glued or screwed to the corners of the bases) if you don't want or need spikes. The important thing is to make sure that the bottom of the platform will be at least one full inch (more here is better—up to like 3 inches) off the floor with no obstructions. Measuring in 1" from each edge of each corner, I marked the point where those two lines intersected. I wanted to create as wide a stance for the bases as possible for stability yet have a solid and secure mount for the spikes. Keep in mind, our finished product will be slightly over 5' tall and have only a 16" by 10.5" base. Next, I selected a drill bit just slightly smaller than the thread on the field points so that I could thread them directly into the wood. Here again, exercise caution to keep the holes perpendicular to the surface of the plank. Any angle deviation from 90 degrees here will cause the platforms to sit unevenly and tip more easily. Once drilled, I threaded the points into the base and prepared to mount the pipes.

Placing the base vertically on edge along its front face and with three pipes laying long ways away form me, I inserted them one at a time through the top of the plank (the spikes are now in the bottom) so that I could see them protrude through the bottom of the plank. I carefully aligned them so that the bottoms of the pipes were flush with the bottom of the holes in the base by angling the base slightly forward. Then I used the drill to run a small pilot hole for the screws, as straight into the base as possible, through each pipe and on into the wood.

Next, without moving the pipes or the base, I ran a screw into each hole until it bit solid. I then carefully flipped the entire assembly so that the edge I had drilled and screwed was now facing up and the un-drilled side was down. Now I could drill the holes in the other side of the pipes and plank base. On this side I drilled two holes, as widely spaced as I could, to create a three-point hold on the pipes. One to the far right and one to the far left provided a solid anchor to hold the pipes securely in the bases. I did this for all three bases and had my three tuning devices almost done.

Fetching my bag of polyfil—and my broom—I proceeded to stuff the batting, very loosely, into the center pipe of each unit until it was full from top to bottom. I then loosely filled the right pipe in each of the three stations until it was half full. Finally, I used just a small tuft of batting in the top of each of the left pipes in the units so that it wouldn't look significantly different from the other two tubes to the casual gaze.

My hand drilling turned out to be pretty accurate. All my pipes turned out to be pretty evenly spaced and ran pretty much perfectly parallel, all the way to the top of each assembly. If yours lean towards or away from each other near the top, you can use some metal strapping material or even blocks of wood to hold them the required 1" and 1.5" apart near the top. I really liked the way mine looked without the additional bracing, so I chose to not use it.

Next came the most time-consuming and boring part of the assembly: painting. What can I say? Spray cans, newspapers, well-ventilated area, repeated even, light coats.

What we have done, fellow Musical Meddlers, is create a troika of triple Helmholtz resonators, with each resonator tuned to a slightly different frequency by the amount of batting filling the tube. Since a further purpose of these devices is to diffract directly radiated sound, you now know why I wanted to space them a bit unevenly – hence the 1" and 1.5" spacing between the three on each base.

So where are we? Let's tally the score sheet, shall we? Cash outlay: $59.64 before taxes. That is just 5% of the cost of the commercially available product. Time invested: a tad less than an hour before painting. You can't really count the time while the paint dries, can you? Ha, time to play!
 

The treasure

Initial placement is simple. Place one unit to the outside of each speaker directly off the outside front corner at about a 45 degree angle and about 6" to a foot away. Place the final unit between the speakers, somewhere on the line running front to back, exactly midway between them. These are initial placements so don't obsess. Sit down, fire up the system and pay attention. You can move the central unit forward and backwards along that center tangential line to control center focus and depth. Moving the outside units slightly in and out or front to back will focus and stabilize the image and soundstage. Both have a startling affect on fine-tuning timbre. Season according to taste.

Can you say astounding? Even Tin Ear, whose very name was borne from his propensity to goad me about my neurotic tweaking tendencies, was left near-speechless. Hey, that alone was worth the sixty bucks! Stage depth was increased enormously. The central image was rock solid—stable as the Rock of Gibraltar—and was focused like an electron micrograph! The stage had a discernible coherence outside the far edges of the speakers (when the source material was up to the task). Left-to-right placement took on a corporeal reality that was so spooky-real I had to open my eyes again and again to verify that I listening to a collection of black boxes and loudspeakers. And it only got better.

Timbre was affected in a most-appealing way. From the upper midbass on up through the upper midrange, there was a newly imparted "reality." Strings (from violin to Stratocaster) and piano were more right in both the flavors of their excited strings and the resultant harmonies they made together. Most vocals lost all hint of hardness (when the recording permitted, of course) and even the often-difficult voices of artists like Neil Young, Bob Dylan, and Geddy Lee became more corporeal and inviting.

Try Harp Attack [Alligator LCD 4790], which features the voices of Carey Bell, Billy Branch, James Cotton, and Junior Wells, each playing their own respective harp (that's a harmonica for those of you who are instrumentally challenged) [ed's note: don't feel put out: friendly jabs like this one are instrumental to Greg's writing.]. In the opening cut, "Down Home Blues," the four are lined up left-to-right and take turns soloing. Unreal! Both their location within the soundstage and the sounds of their voices and harps are vibrant, lifelike, and so well recreated in space that you might easily be convinced the four veteran bluesmen were standing in front of you! There is something almost raw sounding about hearing a harp blown live, right in front of you. There is a roughness to the edges, a bite if you will, and a resultant growl that is very hard to get right—under even the best of circumstances. Well with these budget pipes, it was completely right—and in a big way.

"Peggy's Kitchen Wall," from Bruce Cockburn's Stealing Fire [True North TN 57] exposes the background singers as an assemblage of discrete individual voices, behind Bruce and slightly elevated, not a single conglomerate group voice. And the breath-taking "Sp ãén iye so dé lal" from Professor Johnson's HDCD stunner Postcards [Reference Recordings RR-61] is frightening: each soloist has not only an individual place within the recording, but seems to physically occupy his own tiny space therein. I have always used this track for its ability to cause a system to falter or shine, but now... phenomenal! Those little hairs on the back of my neck were reaching for the sky.

Violins, cellos, and even double basses have a bloom and a body about them that are as close to the concert hall as I've yet to experience, short of the concert hall event. The sound of a bow, even the rosin on that bow, has taken on an inescapable and essential truth. Piano voices are so warm, and yet articulately delineated, that you can almost reach out and touch them. Vocalists breathe and move in real space, not some two-dimensional recreation of that space. Delicate percussion instruments, from triangles to maracas, exist in space with their own individuality. A new degree of life is breathed into system.

Copyright 2004 OS&M. All Rights Reserved.