Updated February 15, 2022
In the first part of this series we didn’t include speaker stands. In this part it will become evident why we made this request. The room in which you place your sound reproduction system, and the way it is setup will have a major impact on overall sound quality. As a matter of fact it is of equal importance to choosing the right components. This factor is more often than not completely overlooked or ignored by most audiophiles. Even famous audiophile reviewers are guilty of failing to have a properly prepared room. It is one of the primary reasons their reviews should be ignored. Without a properly setup room there is little value to subjective critiques, because no one else will ever be able to reproduce similar results. By following this guide you, and any other audiophile, should be able to achieve very similar results, regardless of the room.
Common Home Room Floor Types
- Carpet over concrete floor
- Carpet over plywood floor
- Hardwood or tile over concrete floor
- Hardwood or tile over plywood floor
The above list begins with the ideal flooring and descends to the worst. Wall to wall carpeted rooms over concrete have many advantages over all other types. Concrete doesn’t resonate, and the carpet dampens acoustic reflections. If you enjoy listening to vinyl, it also provides the best possible platform for turntables.
Spiking vs. Isolation
Audiophiles like to put spikes and cones under everything. We have to admit that it looks very precision-like, and adds a certain geeky cool factor to the aesthetics, but in many cases it does far more harm than good. Plywood sub-floors are in many ways similar to an acoustic guitar in that they can act as a resonating surface. Spiking a speaker to this type of sub-flooring, whether it has hardwood, tile, or carpet covering, creates a large vibrating sound-box. This is especially true with subwoofers. In most recording studios the monitors sit atop the console, which like a plywood floor, will resonate. This is obviously undesirable. To avoid this, studio monitors are placed on dampening pads, or specially designed isolation stands.
Heavy thick carpeting over plywood creates a stability problem. Unless the speaker is especially heavy, it will not be stable on this surface without some sort of foot, or leg. We recommend adjustable riser feet in this situation because their round flat disc pushes into the carpet, while the carpeting itself acts as an isolator. Spikes are a good choice if you have heavy carpet over concrete. If you have thin commercial type carpet then no additional hardware is needed unless there is a stability issue.
If you have hardwood or tile over either concrete or plywood, you have a serious problem. Installing a large area rug will help. This, however, only goes so far, and if you’re unfortunate enough to have hardwood or tile over plywood, you should seriously consider another room.
Walls and Ceilings
When dealing with walls and ceilings there are basically three types of audiophiles:
- Sound quality matters, but let’s be practical
- I don’t believe flooring material impacts sound
- My listening room is my personal man cave
We assume that most of you will be a Type 1, but if you’re a Type 3, contact your local recording studio supply house immediately and begin hanging acoustic panels and installing bass traps. If you’re a Type 2 then you will never be able to achieve anything near accurate reproduction due to sound wave reflections.
Glass is the enemy! It’s a perfect reflecting surface. Install heavy curtains over windows and close them when listening to music. Large pictures or prints covered in glass should be covered with a heavy cloth when listening. The same can be said for glass top coffee and end tables.Never ever place a table of any type between your listening position and the loudspeakers.
How to Test for Basic Reflections
Simply clapping your hands is a good way to test for reflections. If you clap your hands in an empty room you will hear a light echo created by reflections. Clapping your hands in your listening room should produce no echo. Heavily stuffed furniture can help to further dampen the room.
In the diagram above we illustrate proper speaker positioning. Each speaker is 36″ or more away from the side walls, having this measurement be identical for both is ideal. The front baffle of each speaker is 36″ from the back wall, and the speakers are spaced 8′ to 9′ apart from one another. The distance between the front baffle of each speaker is of equal distance to the listening position, forming an equilateral triangle. There is at least 36″ (preferably more) between the back of the listening position and the rear wall.
In most cases it will be impossible to achieve this exact setup. We have provided it as a reference model. Try to get things as close as possible to the diagram. You may also want to read Speaker Placement by Galen Carol Audio for further reference. This article details the many problems associated with rooms and speaker placement.
The Rule of Thirds, Cardas Room Setup, or the 38% Rule?
The Rule of Thirds involves initially placing your loudspeakers 1/3 of the distance into the room. From there you begin moving them around until the best sound is achieved. In most cases the Rules of Thirds is recommended to improve stereo imaging. While it may improve imaging in some systems, it is not a reliable guide to placement.
The Cardas Room Setup method was invented by George Cardas and is detailed on the Cardas website.
The 38% Rule is the result of research conducted by Wes Lachot, a recording studio design engineer. Lachot was interested in locating points within a room where standing waves were at a minimum. His rule states that there are two points in every room where standing waves are at a minimum. These points are at 38% of the length of the room from the rear wall and 38% of the distance from the front wall. In recording studios the point from the front wall is used because the monitors are close to the engineer, but in most home applications it will be 38% from the rear wall. When used in conjunction with the equilateral triangle positioning instructions above it defines where to place your speakers in the room for optimum performance.
The 38% Rule defines not where to place your loudspeakers, but the ideal listening position. Simply move the equilateral triangle so that your head is at the tip.
In Part 1 of this series we recommended the JBL 4410 monitor for the following reasons:
- The system is a mirror image pair
- They have high and mid frequency controls
- They are good monitors
We recommend that you begin by placing them upright with the tweeters on the outside, and the controls (L-Pads) set to “0”. Zero sets the frequency response to flat, as measured in an anechoic chamber. Notice that the controls are primarily designed to attenuate, or decrease the output of the high and mid frequency transducers. This is to allow for House Curve.
Now, listen to some of the recommended tracks from the Reference Recording List, and set the controls so that the system sounds good to you. When adjusting the controls be sure to implement the changes to both speakers. In the end both speakers should have their controls set to the same positions.
The 4410 can be configured in two different ways:
- High and mid transducers to the outside
- High and mid transducers to the inside inside
Listen to them in both configurations. Which sounded better to you? Feel free to readjust the L-Pads as you listen. Once you have the best sound continue on to the next step.
Speaker toe-in refers to the angle at which the speaker is directed at the listening position. (See diagram below.)
There is no exact answer to how much toe-in your speaker system will require. Some speakers systems, such as the Polk SDA series, require none. Most, however, will demonstrate improvements in overall sound quality and imaging when they are slightly toed-in towards the listening position.
It’s important that both speakers be toed-in equally. The easiest way to accomplish this is with a measuring tape. It’s also helpful to have a partner help with this procedure. Begin by toeing the monitors in 1″. Listen carefully to the vocal imaging. Increase the toe-in to 2″. Again, listen carefully to the vocal imaging. Did it become more pin-point and detailed?
You will need to repeat this procedure several times using various measurements. Feel free to try less than 1″ or more than 2″. The goal is to make the sound-field as life-like as possible. Do not readjust the L-Pads to fix changes in tonality. You will repeat this later.
You should probably repeat this procedure after adjusting tilt, and equalizing the speakers to the room. More on that below.
(In the above diagram we assume an average width of the monitor at 14″. Significantly narrower monitors will require less toe-in in inches.)
Speaker Height and Tilt Angle
Most speaker manufacturers build their cabinets to suit the aesthetic preferences of consumers who intend them for use in their homes. Many modern speakers have narrow front baffles with deep cabinets to make them less obtrusive. There are primarily two or three different sizes of speakers: floor standing, bookshelf, and large bookshelf. “Bookshelf” is a bit of a misnomer because placing your speakers inside bookshelves will greatly reduce their reproduction capabilities. Bookshelf speakers require stands to work properly.
Due to aesthetic considerations during design many floor standing speakers can also benefit from stands. Whether you have bookshelf speakers on stands, or floor standing models, you will need to conduct the following tests.
Begin playing an excellent recording, and set the CD player or media center software to repeat it endlessly. Listen carefully, paying particular attention to the high frequencies. Now, sit on the floor in front of your listening chair. Did the high frequency response decrease? Stand up, and listen some more. Repeat this process, moving up and down, until you get a good idea of how changing your height affects the sound. Did your system sound best in the chair, below, or above it?
Next, measure the distance from the floor to a point mid-way between the tweeter and woofer, or tweeter and mid-range, as the case may be. Using a combination of speaker stands, patio stones, or concrete blocks, raise each speaker so that the mid-way point between the drivers is at ear level when you are in the listening position. Return to the previous recording and listen carefully. Did the sound quality improve? It should have changed making you want to readjust the L-Pads, but don’t do so just yet.
In a live jazz performance the musicians are usually on a stage at least 12″ above the floor. The music shouldn’t sound like it’s coming from the floor or speakers, it should sound more life-like. By raising the speakers your system should be sounding much better, but we’re not done yet.
In the diagram above, the speaker is not at ear level, instead it has been lowered slightly and tilted back. The tilt creates ambient reflections, and may or may not be preferable to the speakers at ear level. In most cases the sound-field will open up and become more three dimensional. This is especially useful with classical music.
Typical tilt angles are 3-5 degrees. In all cases the mid-way point must be angled towards the ear in the listening position (see above). If you increase the angle much beyond 5 degrees the speakers will begin to sound somewhat ethereal. You can use paint stirrers and washers to manipulate the tilt angle.
Not all speakers in all rooms perform well when tilted. The purpose of this exercise is to determine if your speakers in your room can benefit from tilt.
If tilting your speakers improved the overall sound quality then the stand required will be lower than if they were positioned at ear level.
If tilting did not improve the sound or imaging then place them back at ear level.
In both cases it is now time to readjust the L-pads.
Now that you understand the basics go back and repeat everything. Try to refine things even more.
After all the trial and error adjustments are completed, you should have a pretty good idea of your speaker/room interaction, and what works best. You should also know the exact size of stand you will require to complete the system setup.
If everything went according to plan, your system should sound much better, but we’re not done yet. In the next part of this series we will introduce some new concepts to improve it even further.
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