Monday, December 16, 2013

High-end Soundstages - Part 6


In Part 6 of this series we will start moving things around and improving upon what should already be an enjoyable experience. As mentioned earlier, the advancement of the high-end is a process, not an event. Many pieces of gear have most likely come and go in your upward quest for audio nirvana and the typically overlooked element is your speaker positions. When something is “not right” about the sound of your rig a trip to your local audio salon finds its way in your weekly “to do” list. Without a doubt changing equipment has the biggest impact on the overall sound of your system, but the position of your speakers has the greatest impact on the size and shape of the soundstage (and the smoothness of the bass).

Many may argue “the cart before the horse” or even “the weakest link” analogies when embracing a soundstage, and rightfully so: you must have good gear to get a good sound stage. But conversely, bad speaker positioning will make even the best gear sound mediocre or even worse. The point is that tweaking your system involves more than swapping equipment or software. Getting everything in your audiophile repertoire to synergistically work together takes wisdom, planning, and patience.

If you have been following this series, in Part 1 you saw how monophonic sound progressed into stereophonic sound and from there into what is presently called the high-end. From Part 2, you know what happened in the audio industry as the 3-dimensional soundstage developed favor and why rectangular listening rooms are preferred. You also learned how moving speakers influences bass prominence and how the listening room itself influenced the overall sound. From Part 3 you learned how to minimize room bass resonances by mathematically positioning your speakers based on your room dimensions and roughly how high off the floor they should be. You also know that floor rugs are good and that your listening chair (a.k.a. the "sweet spot") are about the same distance from the rear wall as the speakers are from the front wall. In Part 4 you identified the locations of first reflections in your room and hung sound absorbers and diffusers in the appropriate places. In Part 5 you assured yourself that your speaker wires had proper electrical and absolute phasing. And you used an RTA app on your smart phone or tablet to take a snapshot of your system’s smoothness.

In this part, we will explore how to tweak your speaker positions so you can achieve the biggest soundstage possible in your listening room regardless of its size or shape. I presume that you have done all of your homework assigned in Part 4 and purchased the two versions of source material you will need to follow these tuning instructions. Remember to put masking tape securely on the floor to mark the current location of your speakers. So with this introduction, make sure your ears are REALLY clean (I am serious about this) and let’s get on with it.

SOUNDSTAGE WIDTH-AND-HEIGHT: It is when your speakers are properly positioned that the sound will appear to come from other locations than the speaker centerlines and places in between. Ignoring for the moment the depth of a soundstage, the first soundstage property you want to optimize is its width and height.

You may already notice that the size of the soundstage became altered and the sound may even appear to originate from locations beyond the outside of the speaker centerlines. As you move the positions of your speakers from these points of origination, the size and shape of the soundstage – either good or bad – will follow. To help you remember how it changed, you must create a grid on the front wall so you can see exactly how things changed. Hang colored yarn (use a high contrast color to that of the front wall) and thumb tacks every 12 inches from floor-to-ceiling and from the side walls toward the center making an easily-seen grid. Draw a sketch of your room including the yarn grid and record the distances from the side wall (Ds) and the front wall (Df) of your speakers. This will help you remember where the speakers were when you observed this particular-sized soundstage.



Grid Lines on the Front Wall Made from Colored Yarn and Thumb Tacks

The procedure you will use to note the height and width of your soundstage is simple:
  1. Sit in the sweet spot
  2. Play the track
  3. Close your eyes while listening to the track
  4. Listen to the ambience of the recording rather than the fundamental notes of the sounds themselves. Listen deep into the noise floor for those subtle ambience clues.
  5. With your eyes still closed, point to where you perceive the edges of the soundstage to disappear (no echoes or instruments emanate from beyond this point)
  6. Open your eyes and record the position your finger is pointing to on the grid of the front wall by making a small X at their perceived point on your paper.
  7. Add about a dozen or so points to this 2-dimensional paper chart at regular intervals, enough to tell you where at any point on the grid the limit of the soundstage is. Like connecting the dots on a child’s drawing, you will eventually transform onto the paper the psychoacoustic illusion your system creates.
  8. Repeat steps 1-6 on different sheets to account for minor head movements and different seating positions before changing a speaker’s position (use same Df and Ds distances and make more than one sketch)
  9. Create a “master” sheet for that Df and Ds position by averaging together these multiple subjective measurements

For example, put on track 12 of the Red Book version of the Norah Jones album. Listen to the guitar in the first 10 seconds of this track but instead of listening to the guitar, listen for the echoes in the room in which the recording was made (the echoes in the studio and not the artificial echoes created by your listening room). You may have to turn up your system pretty loud to hear these subtleties but play this piece at a level where you not only hear the nuances in the strings but also the slight reverberations in the studio. Stop the playback before Norah’s voice chimes in and replay this track’s first 10 seconds until the sound level is adequate for you to hear these subtle details. Below is a sample of what your first marked-up sheet may look like when focusing on the echoes in the first 10 seconds of track 12.


Sweet-Spot Sketch of a Soundstage

The challenge here is to subjectively determine where in 2-D space the echoes (and possibly the instruments) appear to be. As you reposition your speakers, you will notice slight shifts in these positions and your sketches will help you remember which location expanded or better defined the size and shape of the resulting height and width of the soundstage. Using the same signal source allows you to repeatedly test for improvements or degradations. Before moving things around, let’s take a crash course on how to listen.

LISTENING TECHNIQUES: As mentioned, listening deep into the noise floor for ambiance clues helps you understand the current size and shape of your soundstage. Take your time and learn how to listen for these clues on as many different types of music as you have available, especially your personal favorites. After you understand where these ambiance echoes exist, move your attention to the details of the instruments themselves. Listen for the sonic information just before and just after a single note is played. The “attack” and “decay” of these notes determines the quality of your system, or rather the accuracy of its reproduction but has little to do with the creation of the soundstage. However, as your speakers are moved around and the soundstage size improves, you will be able to notice other such details that were constraining your system’. Let’s take an in-depth look at the Red Book version of track 1 "Don’t Know Why” for these types of clues.

This song begins with a simple trio of acoustic guitar, drums, and bass. The guitar starts playing on its solid-wire strings and is hand-strummed with fingers and thumb. This sound is very different – softer – from that played with a stiff guitar pick, and reveals the lower midrange nuances of the guitar and its body resonances as opposed to the harmonic content of the string. The drummer swishes wire brushes on the snare drum to blend this softer sound with the soft guitar not only setting the tempo but also re-emphasizing the mood of the track. A double-bass is also hand plucked similarly revealing its character announcing the marked differences between this instrument and its fretless electric bass guitar rival. Full-body resonances of the double-bass dominate the lower scales and just as you settle into enjoying the relaxed atmosphere created by these masterfully-wielded instruments, Norah’s silky voice chimes in at a similarly low level almost as if the guitar gave it birth. But with the next word falling from Norah’s lips, she quickly takes command of the performance by raising the volume of her voice to just the right level where it draws your attention to it without becoming overbearing. Your ear is masterfully redirected from the accompaniment to the vocals without disturbing the enjoyment of the entire performance – in other words, a synergy between musicians occurs and this is what sets true artists apart from others. At that moment, all of the nuances created by the vocals and instruments – their echoes and reverberations – define the shape of the soundstage. You can literally point to where the snare drum is with respect to the double-bass and the piano. You can tell where Norah’s voice is with respect to the double-bass. The positions of the instruments you should hear (as laid down by the recording engineer and revealed in the Red Book version) are this:



Track 1 General Instrument Positions

Everyone automatically does this step without observing the cooperative process your brain/ear takes in making these positioning assessments. Directional hearing is as natural as breathing and from it we understand where a sound originates. However, training your ear to hear more than these fundamental positioning clues will make the difference in creating a larger soundstage. The detail of the instruments is where you should now focus, that is, how much distance between each of them can you subjectively assign? Do they sound like they are all coming from dead center or is there “air” between each one? Does the high-hat appear in the same position as the snare drum or is it too in a slightly different location? How far to the right of the bass player is the drummer’s cymbal positioned? Is the piano always dead center or do the high notes appear a little to the right and the low notes to the left? At 1:10 into this track, can you hear the low-level background singers (actually Norah again in an overdub) and where are they positioned with respect to Norah’s lead voice? Your answers to these subjective questions will help you fine tune your speaker positions.

Take good notes about what you hear with your speakers in their current position. Establish a baseline so that you can refer back to your current observations before repositioning your speakers. Use the grid lines on the front wall to help you picture exactly what your system is doing. Create another picture of the soundstage showing the detailed position of instruments after listening to more than their relative locations.



Track 1 Detailed Instrument Positions

After you understand the answers to all of the above questions and have made a detailed picture of instrument positions, now is the time to move your speakers.

POSITIONING THE SPEAKERS: Your goal is to create the tallest and widest soundstage possible. Moving your speakers forward, backward, left, and right will alter the overall size of the soundstage each time you change their positions. Begin by making large moves of about 4-6” in one direction and redraw the shape of the soundstage on one chart and the instrument positions on another. For now, keep the speaker faces parallel to the front wall. Which direction you choose to move your speakers is up to you but in general moving them out from the front and side walls will make the soundstage bigger to a point after which additional movement in this direction begins to shrink its size. Remember that moving your speakers also changes the bass smoothness and a new RTA measurement should be made after you reposition them to see if the perceived improvement in the size of the soundstage has detrimental effects on the smoothness of the bass. The process is simple:

  1. Move your speakers to the new position
  2. If there is an initially observed improvement in the soundstage size, especially in the air between instruments, you have moved them in the correct direction
  3. If the sound stage is somehow compromised (over-emphasis in any individual instrument or shrinkage of the size), move them one inch at a time back towards their original position
  4. Make two diagrams of the changes in instrument positions and in the height and width of the soundstage
  5. Listen to the new position for a prolonged period with your favorite music to see if the improvement impacts the detailed instrument positions in a constructive or destructive way
  6. Make an RTA measurement. If a large swing in bass smoothness is noted, evaluate if this is an acceptable loss compared to the gain in the size of the soundstage.
  7. If you are happy with their new location, move the masking tape on the floor to mark this new position
  8. Repeat steps 1-7 in smaller increments than before.

Remember that speaker positioning is an iterative process where one location will definitely fail and others will succeed. Some positions you find will have a great sized soundstage that will compromise bass smoothness and others will have really smooth bass but fall short in the soundstage size. The way you select your final position becomes a compromise of these two parameters. I prefer to listen to a large, detailed soundstage with a lot of air between instruments and use other methods to help correct bass smoothness if possible.

While symmetrical placement is a rational assumption, you may find that asymmetry is preferable especially in non-symmetrical rooms. However, start by moving both speakers the same amount and in Part 7 we will use another round of tweaks for fine tuning. Remember, proper speaker placement is an iterative process of which this is the first round of many. Do not be too hasty in judging a change. Allow yourself time to understand what did and did not happen as a result of the move.

Always adjust your speakers for an optimal soundstage size as observed from the sweet spot. However, minor changes in position can expand the appreciation of the soundstage from other than this ideal location and additional experimentation can only tell you if it is or is not possible to do so.

SUMMARY: From your drawings and extended listening, you should now begin to see the effects of speaker position, bass smoothness, and soundstage size. You may have found that asymmetrical positions create a better soundstage than symmetrical ones and you may have to compromise on bass smoothness to get a larger soundstage. You may be fatigued by moving your speakers and need a break, especially if you have large speakers and it takes two people to move them.

Coarse positioning (movements of several inches in one direction) will quickly get you near the preferred location; smaller movements from this coarse location (those less than one inch) will eventually find that ideal position. RTA measurements will tell you what compromises you made by moving your speakers.

In Part 7, we will see the last adjustments you can make to improve the air between instruments at the current speaker positions. Until next time…

Links to the entire series:
Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7
 
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.

http://www.amazon.com/dp/B00QFIAC3G

My other titles include:


Copyright © 2015 by Philip Rastocny. All rights reserved.

Sunday, December 15, 2013

High-end Soundstages - Part 5


Listening rooms sound best when speakers are properly positioned but the room itself plays an integral and synergistic part in your system’s ability to perform at its peak. In Part 5 of this series we will make sure speaker wiring is proper and then take a snapshot of your system’s uniformity.

If you have been following this series, in Part 1 you saw how monophonic sound progressed into stereophonic sound and from there into what is presently called the high-end. From Part 2, you know what happened in the audio industry as the 3-dimensional soundstage developed favor and why rectangular listening rooms are preferred. You also learned how moving speakers influences bass prominence and how the listening room itself influenced the overall sound. From Part 3 you learned how to minimize room bass resonances by mathematically positioning your speakers based on your room dimensions and roughly how high off the floor they should be. You also know that floor rugs are good and that your listening chair (a.k.a. the "sweet spot") are about the same distance from the rear wall as the speakers are from the front wall. In Part 4 you identified the locations of first reflections in your room and hung sound absorbers and diffusers in the appropriate places.

I presume that you have done all of your homework assigned in Part 4 and purchased the two versions of source material you will need to follow these tuning instructions.  So with this introduction, make sure your ears are REALLY clean (I am serious about this) and let’s get down to business.

SPEAKER WIRE ELECTRICAL PHASING: The sound from any single speaker regardless of its position in a room will always appear to come from the centerline of that speaker. When in proper electrical phase (+ signal from the amplifier reaches the + terminal of the speakers, that is to say the speaker wiring is proper) phantom sound should also appear from directly in between your speakers. To test that your speakers are wired in correct electrical phase:
  1. Sit in the sweet spot
  2. Play track twelve (Nightingale) on the Red Book version of the Norah Jones album
  3. See if Norah’s voice emanates from in between your speakers
If it does, your speakers are in correct electrical phase; if not, one of the speaker wires must be reversed. To remedy this issue, recheck the polarity from amplifier-to-speaker on both channels and correct the improper wiring connection.

SPEAKER WIRE ABSOLUTE PHASING: As you listen to any signal source whose speakers have correct electrical phase, the sound will also appear to come from either slightly forward or slightly behind your speakers. The correct orientation is slightly behind your speakers. To test for correct absolute phase:
  1. Sit in your sweet spot
  2. Put on track twelve again of the Norah Jones album
  3. See if the sound of the introductory guitar and Norah’s voice comes from slightly behind your speakers
If they do, the absolute phase of your speaker wires is correct. If not, the absolute phase of your speaker wires is incorrect. To remedy this issue, swap the wire polarities at BOTH speakers regardless of their current orientation (move the wire that is now on the + terminal to the terminal, and move the wire that is now on the terminal to the + terminal on both speakers).

Improper absolute electrical phase is a result of one of your pieces of gear (amp, preamp, CD player) internally inverting the phase. Without placing blame, the easiest way to resolve this issue is to correct the problem at the speaker terminals. Now that you are certain the proper electrical and absolute phases are correct, listen to your favorite reference recordings to verify these two phases.

PLANES OF ADJUSTMENT: There are a total of five planes of adjustment you can make to properly aligning your speakers. The three adjustment planes most people are familiar with are:
  • left/right (moves your speakers towards or away from the side walls)
  • front/back (moves them towards or away from the front wall), and
  • up/down (raises or lowers them from the floor)

These three adjustment planes get your speakers in that part of the room where the bass (here defined as those frequencies under 300Hz) is smooth and the soundstage (frequencies above 300Hz) is decent. Moving them from this point may improve the soundstage at the expense of bass smoothness, a compromise only you can decide which is better or worse.

But to fully appreciate the front-to-back dimensionality possible with just two loudspeakers, the last two planes of adjustment are used to fine tune them while minimally impacting bass smoothness. These last two planes are:
  • toe in/out (twisting the speakers toward or away from the sweet spot), and
  • pitch back/forth (raising or lowering the front of the speakers)

This does not mean you shouldn’t move your speakers. On the contrary, mathematical models should be used only as guidelines or starting points and typically fall short of peak performance when applying them to real-world situations, especially when it comes to rooms in homes. Walls assumed to be plumb, square, and completely flat are most likely tilted, cocked, and warped. So the first step in determining where to go is to move your speakers from this starting point.

TRACKING CHANGES: Smart phones and tablets are great communication and productivity tools and most of them can easily become inexpensive audio analyzers. A good Android tablet/cell phone app for observing your system’s response is available here and a good iPhone/iPad app is available here. You can measure the relative smoothness of your system at your sweet spot by playing a quality pink noise signal through your system. Ten minutes of high-quality pink noise is available for free here that you can play in your CD player or music streamer.

Although your tablets/smart phones are not built to the same standards as a professional RTA and calibrated microphone, they are far better to use than by trusting your ears alone. Use the instructions provided with the app to calibrate your tablet’s/cell phone’s built-in microphone to the software and you should have a pretty decent way of preserving the actual results of your efforts.
Some devices, such as the Samsung Galaxy S III from AT&T, have built-in filters that skew low-frequency readings (those under 300Hz) and should be ignored. However, relative changes between measurements will remain reasonably valid. The picture below shows two RTA measurements made before and after moving my speakers just two inches closer together.


Two RTA Measurements with a Samsung Galaxy S III

A reminder is needed here regarding measurements with RTA devices and real-life soundstage observations. While RTAs show you how smooth your system produces sound, they show you nothing about the height, width, or depth of the soundstage. RTAs are most useful in understanding problematic room resonances and identifying annoying frequency peaks. There is no app that can tell you anything about the size of your soundstage.

With your speakers set in the mathematically-calculated position described in Part 4 of this series, use your RTA app now and measure the smoothness of your system’s response at your sweet spot. This should be your “reference” or “starting point” measurement. Subsequent measurements will show you what changed regarding your system’s overall smoothness as a result of that change. Do this measurement now.

In Part 6 of this series, we will start moving things around and use subjective and objective measurements to decide if a change is desired or a disaster. You will continue to use your RTA app to objectively measure what these changes do. And I will help you understand how to be a better listener. So until next time…

Links to the entire series:
Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7
 
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.

http://www.amazon.com/dp/B00QFIAC3G

My other titles include:


Copyright © 2015 by Philip Rastocny. All rights reserved.

Thursday, December 12, 2013

High-end Soundstages - Part 4

Dedicating enough space exclusively for your loudspeakers on the speaker-end of your listening room is usually the biggest challenge with which audiophiles grapple. Allocating 1/3 to 1/2 of this room for nothing but your speakers pretty much means compromising on using this room for any other purpose. Unfortunately, to get the largest, 3-dimensional soundstage possible this is what you must do. Realistically, however, most people cannot do this or the listening room you use has other compromises. Most people must live in the same space in which they also listen to music so a listening room becomes a multipurpose room. Does this mean that it is impossible to get a good soundstage from such a room? No. Let's see what can be done on a practical level.

If you have been following this series, in Part 1 you saw how monophonic sound progressed into stereophonic sound and then into what is presently called the high-end. From Part 2, you know what happened in the audio industry as the 3-dimensional soundstage developed favor and why rectangular listening rooms are preferred. You also learned how moving speakers influences bass prominence and how the listening room itself influenced the overall sound. From Part 3 you learned how to minimize room bass resonances by mathematically positioning your speakers based on your room dimensions and how high off the floor they should be. You also know that floor rugs are good and that the listening chair ("sweet spot") are about the same distance from the rear wall as the speakers are from the front wall.

In this part, we will explore how to treat your room acoustics so you can achieve the biggest soundstage possible in your listening room regardless of its size or shape. You will also understand better what helps to enhance the size of this soundstage and what to avoid. Here we will address issues above 300Hz, those frequencies where directional imaging cues occur. So with this introduction, let's roll up our sleeves and get to work.

STANDARD SIGNAL SOURCE: At this point, you should be listening to your favorite music in your sweet spot becoming familiar with its new attributes. You may have already noticed a change in the size and shape of the soundstage and maybe not. What we need to do next is all get on the same page and start listening to what readily-available recordings can tell us about what to do next. The first conventional (AKA Red Book or 16 bit/44 KHz) recording that well reveals a soundstage's dimensionality is:


Norah Jones Come Away With Me (Red Book)

If you do not have this recording, you need to buy one now since I refer to it constantly to explain what to listen for in specific passages. While it may be tempting, DO NOT use the MP3 version of this recording in this positioning process since the MP3 compression masks the potential three-dimensionality of an uncompressed Red Book version. However, you should play an MP3 version later to understand the differences and compromises between these two popular digital recording formats.

The Red Book version will suffice to a point but another round of tweaks requires a better signal source. To permit reliable A-B comparisons and assure yourself you are moving in the correct direction, it is best to use the same program material for both positioning rounds. I will use a high-resolution version of this same Norah Jones album and I suggest you purchase the $30 download it here:

Norah Jones Come Away With Me (high resolution)

Download the highest resolution your player/streamer can handle (use the pull-down menu to see what format your streamer can play). This description uses the 24-192 FLAC version. Other similar Red Book and high-res recordings may be used once you better understand how to listen or rather what audible cues to listen for (something else that you should begin to understand as a result of this exercise).

Tweaking is an iterative process, one that takes a lot of time and patience, along with critical listening. As we progress, movements in speaker positions may vary from as much as 4” to as little as ½” with each move making gains in some respects and losing gains in others. The final positions will most likely fall into “your personal preference” category as they should to leverage those strengths you prefer. Allow yourself time to embrace the sound of the relocated speaker and listen to a variety of familiar music after making a location change, typically over several days. You may already be intimately familiar with many different recordings (your personal “favorites”) and I suggest that you listen over and over to those pieces focusing primarily on soundstage width and height during this time, especially the extreme outer edges. Before we begin listening, help your room reveal more of what your stereo can produce by eliminating simple physical impediments, here being first-reflections.

IDENTIFY FIRST REFLECTIONS: First reflections are the surfaces the sound from your speakers strike on the way to your ears. Like balls bouncing off the cushions of a pool table, sound bounces off the surfaces of every object in your listening room. These bouncing sounds arrive at your ears at different times than the direct sound from your speakers. When the level of reflected sound is high, it interferes with the ear-brain interpretation of the location of the direct sound. In other words, reflected sound messes up the soundstage and should be absorbed or redirected to minimize this interference. This is a concept in room treatment called the “live-end, dead-end” or LEDE where the part of the room in which the speakers reside is deadened to absorb these undesired first reflections.

Before we start identifying where these first reflections are, you must remove all furniture from the speaker half of the listening room. Do this now. Doing so allows you to easily identify exactly where on the walls, floor, and ceiling these reflections originate by simple line-of-sight observations. You can return these items to that side of the room later and observe what compromises you have made by re-introducing this furniture near your speakers.

USING A MIRROR: Begin by identifying where the first reflections are in your listening room as observed from your sweet spot and then damping them out. This part is pretty easy but requires some masking tape, a friend, and a mirror (a flat 12” by 12” square will do just fine). All you have to do is move this mirror against the flat wall until you can see one of the speakers and then put tape around that visually-identified area. To identify the areas on these surfaces where first reflections originate (and where sound absorption should be placed in the dead-end of your listening room), do the following:
  1. Sit down at the sweet spot.
  2. Have your friend hold the mirror flat against the left wall.
  3. Move the mirror around on the wall until you see the LEFT speaker.
  4. Put masking tape on the left wall framing the area where you can see any part of the left speaker.
  5. Continue moving the mirror around on the left wall until you can see the RIGHT speaker.
  6. Put masking tape on the left wall framing the area where you can see any part of the right speaker.
  7. Repeat steps 2-6 for the right wall.
  8. Repeat steps 2-6 for the front wall, left side.
  9. Repeat steps 2-6 for the front wall, right side.
  10. Repeat steps 2-6 for the floor.
  11. Repeat steps 2-6 for the ceiling.

If there are multiple seats at the sweet spot, repeat all of these eleven steps for all alternate seating positions.

The taped-off areas on the walls, floor, and ceiling are the locations where sound absorption is necessary. In your decorating decisions for this room, place sound-absorbing panels or hang tapestries at these locations so that the sound is reflected less at these critical points. Hang the tapestries from 1”x2” boards to permit adding acoustic batting behind them. If the first-reflection areas are windows, put soft but heavy curtains on the windows that can be easily raised and lowered. There are many suggestions for both DIY and professional room treatments in the Rives Audio section at http://www.audioasylum.com/forums/rives/bbs.html.

 Use a Mirror to Locate First Reflections in the Dead End

For aesthetic reasons, ceiling treatments are usually the hardest to include in your listening room. You can disguise such a treatment as an indirect-lighting ceiling fixture, especially if there is already a ceiling light nearby. Build an absorber panel as you would for a wall panel (use an Owens-Corning #703 2’x4’x2” fiberglass panel). Frame it at the edges and cover with coordinated cotton fabric. then suspend it uniformly from the ceiling with wires and hooks. Take down the panel. Connect a rope light to the existing ceiling fixture. If the ceiling fixture is not above the absorber, use some plastic self-adhesive electrical channel to help hide the wire from the fixture to above the absorber. Re-hang the absorber. Hide the rope light on top of the absorber and you now have a sound absorbing room light.

If you choose not to build your own panels, you can also buy sound absorbing panels from many sources including a thrifty manufacturer at http://www.readyacoustics.com/diy_acoustic_panels.html.

So far you have taken care of the DE half of the LEDE concept. The LE portion identifies the first reflections in the sweet-spot half of your listening room. Unlike the DE half, the LE half must disperse the sound at these identified locations to randomize their otherwise predictable interference patterns. Use what is called a diffuser to break up these undesired uniform reflection patterns. Identify where this diffuser should be by performing similar steps with the mirror but this time while looking at the back wall from the sweet spot at all listening positions. Tape off the area for the diffuser.

 Use a Mirror to Locate First Reflections in the Live End

DIFFUSERS: In keeping with the Live-End-Dead-End (LEDE) approach to room design, the live end (sweet-spot half) should be reflective and the rear wall is critical in properly contributing to this reflectivity. Here the rear wall should not only reflect sound, it should disperse it in a controlled manner. The human ear is most sensitive those frequencies produced by the human voice (300Hz-6000Hz) so it makes sense to focus on dispersing these frequencies. However, diffusers with a 300Hz cutoff will stick out into the listening room quite far. A good compromise is one octave above the lowest frequency, or a diffuser dispersing sound between the 600Hz-6000Hz range. This LE reflective area identifies the smallest diffuser you should use.

You can buy diffusers in various sizes from many manufacturers such as Overtone Acoustics, but you can also easily make one yourself if you have the time and are so inclined.

 Grid Assembly

Below is a pattern for four heights of 1”x1” square blocks that easily diffuses frequencies within the range of 600Hz-6770Hz. Assembly is simple gluing these blocks to a piece of ½” thick plywood in the positions determined by the number in the table below.

The diffuser below makes one panel 12”x12”. Make multiple panels at least the size of the masked area on the back wall to properly diffuse the sound from the rear wall (a 2’x4’ panel needs 8 of these, 4’x4’ panel needs 16 of these, etc.). These finished panels are very heavy and must be attached to the wall studs for proper support.

0
3
4
1
2
3
3
1
4
2
3
3
3
0
1
4
2
1
1
3
3
2
1
1
3
1
1
3
1
3
2
2
1
0
2
2
2
2
2
2
0
4
3
2
3
2
1
1
3
3
1
1
3
1
1
3
4
3
1
3
2
3
2
1
2
0
3
2
4
2
1
0
2
3
2
1
3
1
2
2
3
1
3
4
2
0
2
4
4
0
1
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1
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1
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1
0

Block Heights: 1=2.823”, 2=5.642” 3=8.465”, 4=11.287”

At this same time, it is best to get whoever is involved in decorating your listening room to understand why things are placed where you have decided to put them. Compromise is the key to a successful relationship and in your listening room such compromises should be weighed against audible effects. Keep your spouse (substitute the appropriate politically-correct term here that describes your relationship) involved in your decorating decisions now instead of having him/her move things around later for aesthetic reasons or otherwise.

Keep to the LEDE plan and you will have a good listening environment, one that can reveal the full potential of your system. In Part 4 of this series, we will describe how to use the Norah Jones signal sources to fine tune the location of your speakers. In this part, I will explain what to listen for in various passages so movements and changes for the good or bad can be correlated.

HOMEWORK: Make sure you have the reference signal sources for Norah Jones album Come Away with Me. Add the absorbers and diffuser to the room now at the appropriate locations and get used to the soundstage with your favorite songs and tracks. This will help you in Part 5 of this series when we start systematically moving things around.

Links to the entire series:
Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7
 
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.

http://www.amazon.com/dp/B00QFIAC3G

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Copyright © 2015 by Philip Rastocny. All rights reserved.