TO SET UP A DEDICATED LISTENING ROOM
WITHOUT FANCY TREATMENTS
by Steve Deckert
this article, I'd like to show anyone who's serious about a listening
room how to set one up with little or no room treatment. Obviously
with the complexity and variety of room acoustics out there, your
results may vary, but odds are you will find it an improvement over
you've spent much time on this web site, and looked into our room
treatment sections you may have discovered that room acoustics
is a fairly serious science and it's usually not solved by random
placement of room treatment products. We feel that your room is
usually around 60% of what you hear coming from your stereo. Most
people either don't believe this, or just haven't grasped it's reality.
hard to stomach the fact that so many audiophiles concern themselves
with connectors and power cords and all the fancy tweaks when these
at best pale in comparison to the effect of room acoustics. The
biggest problem is most of us don't have a room we can use for JUST
our stereo and since we've never had one, or heard our stereo in
one, it's hard to really grasp what the differences would be. For
many of us, if we could some how magically hear our stereos in a
dedicated properly setup room for just a few seconds, it would be
enough to suddenly justify having one. Basement rooms would be built,
garages would be converted, maybe even kids kicked out to gain use
of a bedroom!
I can say, is that in a decent room where everything is ideally
setup, the layers and layers a soundstage take on is so holographic
that music takes on a whole different side, one that is highly addictive.
So if this is you, or you can find a small dedicated room, or have
the luxury of arranging your living spaces around your stereo, read
story starts with a dedicated listening room, with thick carpeting,
real plaster walls, high ceiling.
our search to treat a conventional listening room to a degree that
the changes were easily noticed, we ended up using quadratic theory
diffusion carefully balanced with diaphragmatic absorption to deal
with the reflection points and room peaks that are responsible for
trashing good imaging. This was a little more serious than buying
a couple tube traps.
final result of what we did was a project that was shared with everyone
in the form of D.I.Y. Blueprints. These are available in our online
catalog. To effectively treat our room we had a total of 14 units
that added over 2100 pounds of mass to our listening room. And that
is actually what it took to effect a noticeable result, and turn
a rather small 13 x 15 foot room into a good performer.
year when we built our new shop for manufacturing our Zen triode
amps, I needed a listening room there for testing and evaluation.
Here was an opportunity to build a listening room from scratch...
you can imagine the things that were going through my mind. After
dusting off the Masters Handbook of Acoustics and reading it cover
to cover three more times, I had a healthy fantasy of what I could
do and it was lush let me tell ya. After all, I would be entreating
customers or potential customers there and first impressions are
the lease was signed and I found myself building the interior of
our new place all by my lonesome. Between the stress of moving a
business without problems and the reality of not wanting to give
up 16 feet of my building for a listening room, I gave up and decided
to slap together your typical drywall room at a width of only 12
feet. Between the concrete slab, drop ceiling, and cheezy walls
I knew it would be bad. I thought, hey... I'll create a worse case
scenario here, and then somehow make it sound good just to encourage
the REAL world folks who would likely find themselves in similar
situations. So with that, I made the room a depth of 22 feet which
if you have the Masters Handbook of Acoustics, you would know is
just about the worse ratio you could have for good sound.
rational in place, I built my listening room/office and found myself
standing in an empty hard room, concrete floor, measuring the decay
time of a hand clap. It was ridiculous, I don't even remember now,
but not 50 ms. I would be shooting for. Something like 2.5 seconds
was the minimum reverb time. Well, this was certainly going to be
challenging I thought as I continued to handicap myself by installing
carpet with no padding.
finished, I grabbed a pair of speakers, a Zen amp, and a CD player
and tossed them into the room to get an idea of what was going to
have to be done. I hit play and then stop. The second of time that
elapsed between the two buttons almost made me sterile. My ears
were so offended that I took everything back out instantly and went
home. Later that evening the realization of what a challenge it
would be to treat this room was starting to set in. But hey, if
I can't do it, how could I expect anyone else to conquer their acoustic
decided that I wouldn't have time to build more room treatment,
so I was going to have to steal the units from my own personal listening
room and take them over to the new place. Saddened at the thought,
I told myself that it would be so good over there when I was done
that I'd do my listening there anyway. (Yea right..)
dropped all 2150 albs. of diffusers and bass traps into the room
and dragged another pair of speakers back in for test number two.
time when I hit play, it took around 5 minutes before I ran out
of the room in disgust. It was frankly the worse sounding room I've
ever heard in my life! I was paralyzed with Father Murphy-itis.
Intensely annoyed for days, I avoided the issue by not entering
the same time I was able to hear my own stereo at home minus the
room treatments. That didn't help my spirits any except to say the
room treatments really really worked well, and the room over at
the shop is just really really really really that bad.
the mood to quit goofing around one weekend, I got serious and measured
the room at the new shop. As suspected the difference between a
50 cycle note and a 5000 cycle note was a gain of almost 20 dB!
Now that's hot. In calculating the amount of absorption I would
need to kill this problem I realized that it was almost exactly
the density and area of the carpeted floor had there been good padding
under the carpet. Now with over 2000 lbs of stuff in the room, I
wasn't going to have padding under the carpet so I started absorbing
it in bits and pieces and in a variety of ways. Padding would have
been so much easier.
completed, and after building a permanent bass trap out of an unused
closet, I got the room to become fairly flat with decent response
at 30 cycles and some sense of order. It was now listenable, and
as the weeks went on with continued tweaking and creative room treatments
I had a room that was at least 800% better than before I started.
picture of the end result can be seen above. And it is a listenable
room now. However my personal listening room at home has lost it's
luster and no longer seduces me into hours of evening listening.
In fact, I abandoned it for almost a year.
a whim one evening, I decided to set up some gear in my home listening
room again fairly certain I had forgotten how good it used to sound
by that time. Only this time I set it up diagonally which is something
I had never done at home in any of my listening rooms. But the more
I thought about it the better the idea seemed to be. So I went for
it and took a pair of speakers (that were exiled from the shop because
everyone hated them) home and set my room up.
result really caught me off guard. Before I did it, Still having
the tape marks on the carpet from last year, I set the speakers
up on the old marks and listened in a conventional way. That's when
I learned my own acoustic memory is longer than one year because
it really sounded nasty. It sounded nothing like it used to with
the room treatment. But the exact same gear set up at a 45 degree
axis within the room sounded better in almost every way than the
room did the year before when it was set up conventionally and with
all the room treatment diffusers and such.
what do you do when your sitting in a naked room with two waynky-dink
speakers that no one likes and you're getting better sound and imaging
than you've ever had before without room treatment? Well first you
panic, then you resolve to tell noone and then you desperately try
to figure out what happened.
the way of figuring out what happened I made some revelations about
imaging that I think you may find interesting.
many of you have heard your stereo or someone else's with a strong
center image that exhibits good depth? Now how many of you have
got that center image to shift from one side to the other when you
move your head? Ever wonder why that happens? I certainly have.
In fact I have an ongoing experiment in progress trying to resolve
that very issue. In any case, the bulk of that experiment resulted
in my own recording studio so that I could experiment using recordings
that I created and mixed down myself. I have found the reason for
the shifting effect is two fold, the way it was recorded and an
effect from your own room acoustics.
will probably do a paper, or several, on recording techniques so
I'll leave that out here and just focus on the room effect that
I feel accounts for most of the effect anyway.
it turns out, the reflection points that triangulate around the
room are vastly different when set up on a 45 degree axis. In a
conventional room, the first 4 to 6 reflection points of a speaker
are on the wrong side of the room. In other words the direct energy
from say the left speaker will have it's first four or five reflection
points on the right side of the room. This often ends up with reflections
8, 9 or 10 on the rear wall behind your speakers staged to pass
back by your ears. Since a conventional room is untreated, these
reflections don't loose much energy and continue around the room
with minimal drop in amplitude. In fact in one second of listening
time, the sound from one speaker will reflect around your room over
is important for you to get a real understanding of reflected sound
vs. direct energy. Direct energy is the sound wave that comes directly
from your speaker and passes by your ear. Reflected energy is everything
else that you hear. If these reflections are not reduced in amplitude
AND in time you brain will have difficulty telling which one is
the direct sound and which one is the reflected sound. Localization
cues will be destroyed and the result is an out of focus sound image.
get a grasp on this, turn your speakers around 180 degrees so they
face directly away from you and spend some time listening. Listen
from your chair and from different places in the room. REALIZE that
everything you are hearing is reflected sound and nothing your hearing
is direct energy. In an ideal setup you would want to hear only
the direct energy with none of the reflected energy. Think about
that for awhile during your listening experiment.
difference between good sounding stereo and bad sounding stereo
is I figure at best 50% the room, or specifically how the reflected
sound is handled, and 50% the quality of the gear you have.
I'm thinking about it, and after 20 some years of wondering for
sure, I have concluded without doubt that as far as gear is concerned
the Source is the most important part followed by everything that
follows it and in that order. The only thing more important than
the source is the room you play it in.
look at a conventional setup, as shown in figure 1.
room shown in figure one contains a listening chair and the only
the left speaker for simplicity. The speaker is shown in the color
red. Since most localization cues for the human ear are higher in
frequency, this simple diagram can be used to demonstrate the reflection
points with the highest energy. You may remember that higher frequencies
are more like a narrow beam, the higher the frequency the narrower
the beam. Bass by contrast enclosed in a room with 4 walls is omni-directional.
starts, concern yourself with the black lines and the numbered reflection
points. The yellow lines will be discussed later. These black lines
represent the center of the higher frequency sound beam. Every time
sound hits a surface, such as a wall in your room, there is some
sympathetic resonance in the wall itself as well as refraction.
The black line in figure 1. only shows reflection. This means that
even though reflection point #1 is located behind the listener,
he or she will still be able to hear the result of that reflection
which is resonance and refraction. Refraction would be sound that
didn't perfectly follow the angle of the line, and instead randomly
refracts back to other places. This effect was first talked about
in the 80's when speaker manufactures realized that boxy grills
and sharp corners on speakers were responsible for refraction's
that distracted from the imaging.
point #1 depending on the wall surface could effectively move midrange
and higher frequencies closer to the listener. In other words, it
could artificially drag parts of the soundstage forward.
point #2 is located on the rear wall behind the right speaker. It
would be desirable to have it behind the left speaker if you had
to have it at all. This particular point could have the effect of
enlarging the size of images by stretching them horizontally and
at the same time defocusing the primary image.
point #3 is also on the wrong side of the room causing further confusion
in your perception of the original image.
point #4 is also on the wrong side of the room now behind the listener
again, and even though reflections 5 ~7 are in the correct half
of the room, they simply set the stage for the next half a dozen
reflections to be on the wrong side of the room again.
start to realize it's no wonder we've all spent so many maddening
hours trying to get stuff to image better isn't it?
in figure #1 are some softer yellow lines that show what happens
when you change the toe angle of your speaker by only a few degrees.
If you start at the speaker and following the line you will see
that point #1 has moved left be a couple feet. This would have the
same effect as the original reflection point #1 but with the added
illusion of better width, moving your image to the left slightly.
The second, third, fourth, fifth, and even the 6th reflections that
follow on the yellow line are now on the wrong side of the room.
is easy to see if you study the possibilities for awhile, what is
actually happening to your imaging and the shape and size of your
soundstage by the major location changes of these reflection points
with minor adjustments to your speakers. Also the room in figure
one is a 13 x 15 foot room. I choose this shape because it's more
likely to occur in your homes than a perfectly square room would
be. Naturally, changing the dimensions of the room in Figure one
drastically changes the locations of the reflection points, but
you will find in most cases those first critical 5 or 6 points end
up on the wrong side of the room.
if you added the second speaker to Figure one, and mirror imaged
the points, you would have left channel information in both ears,
as well as right channel information in both ears. Not an ideal
situation at all. The result of this room effect is a projected
mono image in the center of your speakers that shifts to the right
when you move your head to the right and visa versa.
is not real. And if the recording was mixed with the vocalist off
center slightly, the effect will defocus the image more than if
the recording was panned dead center. In this situation, which is
one that 99% of all listeners are in, recording techniques will
be colored to a degree that some will seem to image well and some
just terrible, all depending on where the pan pots were set in relations
to the reflection points in your listening room.
absorption and diffusion to the wall surfaces at these critical
points can reduce the problem to an acceptable level, but never
eliminate it entirely. Nothing is truer than the statement; "You
can't make a bad room sound good" and the reason it's so true
is that "bad" rooms are locked into a particular performance
by their dimensions which can't be changed. All the room treatment
in the universe can only reduce the negative effects of the bad
really hit home as I went back and forth between the two setups.
Let's look at the second setup in the same room.
the same 13 x 15 foot room with the diagonal setup in Figure 2.
in this set up even at the somewhat random placement I came up with
for this drawing, the only points that are on the wrong side are
points 4 and 5. And reflection point 5 considering where it is,
isn't too critical. The lighter yellow lines show what happens when
the speaker is toed in by a few degrees. Basically nothing really
changes much. Dots shift rather than changing walls.
practice I have noticed this arrangement to be far more forgiving
as far as speaker toe angle, and much more flexible to actual speaker
placement. This arrangement also has a much larger sweet spot. The
fascinating thing here is the results. When compared to the conventional
setup with all the room treatment diffusers and so on, I find this
arrangement in the naked room to be actually better.
and after this setup, I used a variety of CD and LP recordings including
several of my own that I recorded myself in my own studio of various
guest musicians and jam sessions. In these recordings care was taken
to properly mike the room, and quality gear was used. From these
reference recordings I could now make a test of the Shifting effect
I spoke of earlier knowing this time exactly how mixdowns contribute
to the effect. The result was this:
the conventional set up shown in figure 1., the effect was present
even in my own recordings. In the diagonal setup shown in figure
2,. the effect was gone. I could move my head as much as 2 feet
in either direction and have no shifting of the center image. Profound.
in short, I now have my listening room back. Before I had a width
of 13 feet and a depth of 15 feet. Now in the same room I have a
width of over 19 feet and a depth of over 19 feet, and it sounds
like it too.
it to a finer level would be fairly easy by purchasing a laser pen
and fastening it to the top of your speaker and then taping mirrors
to your walls to find your exact reflection point centers. This
is where the most energy of each reflection is located. Once you
have found a way to get as many points on the correct sides of the
room respectively, then you can take action to treat the offending
points. For example in Figure 2., the reflections points 4 and 5
are on the wrong side of the room. They could be treated. Keep in
mind that eliminating those points would eliminate all the successive
points and reduce ambiance. This could be a good or bad tradeoff
depending on the actual locations of the points. But nonetheless
it is the approach one would take.
also interesting to notice in this model how the corners become
your friend in the way they triangulate the points. Not unlike a
pool ball. In a conventional setup such as shown in figure 1., the
corners are NOT your friends and ironically for the very same reason.
issues will also be a little different in this scenario when compared
to a conventional speaker and listener placement, but all in all
you should still trap the bass. Since bass does not triangulate
around the room in tight enough patterns to create reflection points
this angled setup will not do much to correct room boom issues.
in conclusion, the results of the diagonal setup were superior to
the conventional setup, the irony is that this was with no room
treatment in the diagonal setup and both with and without over 2100
lbs. of diffusion in the conventional setup.
would say that if you're serious enough to have a dedicated room
for JUST your stereo, you can have a better room than our reference
room was at one time with all the treatment., and do it for nothing.
If you HAVE to have a home theater using a big screen TV and stereo
together in the same room, then this diagonal setup will largely
reduce some of the imaging problems provided you locate the TV as
far back in the corner as possible.