Speaker position influences the size and shape of your soundstage along with the bass smoothness of your system. Unfortunately, optimizing one usually means compromising the other. Can you have the best of both worlds? Read on and let’s see.
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. Part 6 explained how to create a map of
your soundstage and use RTA measurements to show you the compromises
encountered when moving your speakers. Part 6 also explained how to keenly
listen to music so you can know when moving your speakers made a constructive
or destructive change in the soundstage beyond mere positioning clues.
As you moved your speakers about your starting point in Part
6, you eventually found a location that just starts to make the sound fuller
where the psychoacoustic image perceived while listening to a recording got
dramatically wider and higher. You thumb-tacked colored string onto the front
wall and pointed your finger to an instrument’s perceived location on that grid
to keep track of where the image moved as you moved your speakers. At some
point during this moving process, the psychoacoustic image locations appeared
to be well beyond left side of your left speaker, beyond the right side of your
right speaker, and high above them both giving you the largest soundstage
possible.
Along with an increase in the height and width of your
soundstage, you may have begun to notice some unexpected magic also occurring at
this position. Typically you will begin to hear an increase in the
front-to-back depth, that is, the relative position of vocalists and
instruments layered between you and the front wall. Your music begins to take
on a realism that up until that point was overlooked and the closer you get to
that magic location, the more this 3-D effect is enhanced. Here in Part 7, we
will switch to a higher-quality signal source than the Red Book version and
make final tweaks that may surprise you.
ASYMMETRY:
While uniformity conjures up the highest, widest, and deepest soundstage it may
also create the most unpleasant bass resonances. That is, with speakers
positioned exactly the same distances from the front and side walls, bass
smoothness will suffer the most. There is a really simple trick to prevent this
from happening: move one of the speakers away from the wall(s) while keeping
the face of the speaker parallel to the front wall. Moving one of the speakers
compromises the size of the soundstage but can also eliminate one or more nasty
room resonances. So how do you know if the bass has suffered?
As you listened before to the size of your soundstage from
your sweet spot, listen now more critically to the smoothness of the bass. If
there is a sharp rise at some note or group of bass notes, your speakers are
most likely exciting inherent room resonances. For example, as the notes on a
bass guitar or double bass go down the scale, some notes will sound much louder
than others. It is these louder notes that tell you your speakers may not be in
the optimum position for this room. You may be able to measure the low
frequency behavior with a pink noise source and your cell phone’s RTA app
although some cell phones have built-in low-frequency limitations to make your
voice more easily understood. For example, I own a Samsung Galaxy S3 and my
carrier is AT&T. This phone has this built-in limitation so frequencies
below 200Hz are predictably attenuated. Nevertheless, room resonances can be
observed as irregular rises in this reasonably smooth attenuation curve.
Picking Out Room Resonances
To observe room resonances, point your cell phone’s
microphone at the midpoint between the speakers at your ear height from your
listening position. It is best to place the cell phone on a tripod (or similar
small, high table). Play pink noise (inter-station FM noise is good in a pinch)
and look for peaks especially below 100Hz. Most likely, there will be some small
peaks and possibly one or two larger ones. On the side of the room that is most
uniform (no windows or doors nearby), move that speaker toward the other
speaker (about two inches should do nicely) while keeping the face of the
speakers parallel to the front wall. Recheck the effect on the size of the
soundstage by pointing toward the grid as you did before and note the effect on
its change in size. Then measure the room resonances again with the RTA app and
pink noise from exactly the same position and see if the resonant peaks
disappear or at least improve. Confirm your measurements with your ears to
assure that other subtle changes in inner detailing are not adversely affected.
Move One Speaker 2” Toward the Other
Next, move this same speaker forward (toward the sweet spot)
keeping it parallel to the front wall and repeat the RTA measurement and
listening evaluation.
Move This Same Speaker Forward 2”
This new position (Ds+2” and Df+2”) is your asymmetrical starting point. As you did
in moving your speakers around the Ds/Df starting point, do so in small
increments around the asymmetrical starting point until there is a suitable
position where room resonances are minimized. Again, use the grid lines and the
RTA measurements to understand how moving a speaker impacts these resonances. For
now, find a position that has better uniform bass smoothness (makes minor
compromises on the sound stage size). There are more adjustments that will help
return the size of the soundstage next.
TILT AND TOE-IN:
Changing the orientation of a speaker (no longer parallel to the front wall or
the floor) can achieve additional benefits to the size and shape of the
soundstage, especially its depth. By tipping and twisting each speaker, minor
adjustments in the soundstage are possible. Compared to just setting your
speakers at any convenient position in your listening room, what you should
gain as a result of optimal speaker tilt and toe-in is extended frequency
range, wider dynamics, better transient response, and less distortion. Optimal tilt
and toe-in allows you to hear in the newly-created soundstage additional
details about a performance (either live or studio versions) like:
·
The acoustics of the hall or studio were the
recording was made (far corner ambience)
·
Subtle noises of instruments (inner detailing of
finger movements on strings, breathing just before reed instruments are played,
or drumsticks striking the skin just before making a bass note)
·
Very low-level sounds (tapping feet of musicians
or sheet music turning)
You will find yourself listening to a familiar performance –
on of your favorite pieces – in a whole new light listening for these subtle
clues deep into the silence of the recording. You will find more information in
these quiet passages than you ever thought possible and within these
more-silent moments are where these subtleties hide. They were always there but
the interaction between the room and your system prevented you from fully
appreciating them. From this magic position you may also more easily hear
subtle effects when swapping interconnect cables, speaker wires, and power
conditioning. Part of this ability to detect such minor changes synergistically
occurs as you train your ear to hear these effects since with proper
positioning such effects become more audible.
Once you find this magic position, now is the time to change
your source material to the higher-resolution
version since these last subtle tweaks will reveal even more nuances and
bring them into the foreground.
TOE-IN: You
should now be hearing things that you never realized were there from all of the
music in your collection. From that magic speaker location, background details,
whisper-level nuances, and instrument inner detailing all are more easily
observed and seem to change their intensity. Echoes and reverberations reveal a
dramatic sound space and your playback system is definitely not the same as it
was before. Nothing has changed in your equipment, but the sound is radically
different and far more captivating. Swapping to a high-resolution source will
now reveal even more things about your system’s ability to pull out those
nuances and permit your final tweaking. Here, focus on the far corners of the
soundstage and listen to the amount of front-to-back depth.
Start by aiming your speakers toward the sweet spot so that
the face of the speaker directly faces
you. Rotate the speakers at the center of this position and twist them
inwards about 2-3 degrees. See how this small change impacts the depth of your
soundstage. There will be a point that the depth will increase and then
decrease. Back off just a small amount from that angle and continue to listen.
Twist (Toe-In) Both Speakers Toward the Sweet Spot
For example, in the first three seconds of Track 3, “Cold,
Cold Heart,” Lee Alexander introduces the song by artistically taping his
finger on the vibrating double-bass string making it momentarily buzz as it
quickly comes to rest. The double-bass is positioned by the recording engineer in
the center channel relatively forward in the soundstage. After one second, Adam
Levy joins in by plucking a muted a chord on his guitar. Adam is positioned to
the left of Lee at a similar front-to-back location (as if standing next to
each other on stage). Four seconds into this duet Norah’s piano joins in again
in the center channel but its position is behind the double-bass (recorded at a
lower volume so as to not overwhelm her melodic vocals).
Her piano resonances reveal information about the size of
the studio in which it was recorded (this is a different studio from where the
guitar and the double-bass are recorded). You should be able to hear low-level
echoes in the far right and far left corners of the soundstage, especially at
the ceiling level. Norah’s voice joins in at about 12 seconds, her
center-channel voice is positioned forward of the double-bass. Notice that the
artificial reverberation in her voice adds no hint to the size of the room in
which her voice was recorded but makes it far more appealing than a flat,
non-reverberant vocal. Although her voice echoes, it has no depth as does the
piano and consequently as her voice fades, the reverberations remain forward of
the double-bass even though the left and right sides of the soundstage indicate
their borders.
It is difficult to graph what is happening to the psychoacoustic
illusion of three-dimensional space from these movements since everything is
purely subjective. But you can point to where you perceive the most distant
corners of the soundstage and try to map that on your paper. At some point the
sound from this performance appears full without emphasizing either the left or
right sides of the sound stage. Once a twist-angle position is optimized, the
next step is to tilt your speakers.
TILT: If
you have not already done so, now is the time to clearly tape the floor marking
the present position of the speakers including toe-in. Now is also the time to
make sure that your speakers are on quality adjustable spikes (like the
high-quality Track Audio
models or the economical Dayton
Audio versions). What is important about the spikes you use are that they
remain sharp and they lock securely into place. And since room floors are not
themselves completely level, leveling and tilting your speakers with adjustable
spikes becomes an easy task. If your speakers do not have provisions for
spikes, I highly recommend adding them now. I prefer using 3 spikes – 2 in
front and 1 in back – as opposed to 4 spikes since 3 spikes are easier to tilt
in any direction than 4.
With the speaker spikes in place, the speakers properly
positioned from the side walls and the front wall, and the speakers properly
toed in, now is the time to start tilting them. But first, you must make sure
that both are currently tilted back in equal amounts. Hopefully, there is one
flat surface on your speakers to which you can place a digital level. Matching
the tilt angle with such a level assures that both speakers are tilted exactly the
same amount.
Tilting the speaker aligns the time sound arrives at your
ears from the individual drivers of your speakers. Once properly tilted,
transparency, focus, and presence are optimized. With the bottom of the speaker
parallel to the floor, start by listening to the current size and shape of the
soundstage paying attention to focus – the ability to distinguish one
instrument in free space from another. Tilt both speaker backwards about 1/8”
(a half-turn at a time) by raising the front spikes. As before, make small
adjustments and adjust both speakers by the same amount of tilt. You will
eventually find a reasonable tilt position where instruments are rock solid
within a performance (very little drift left/right, up/down, or front/back).
From any familiar high-quality favorite recording of yours,
you should be able to observe this improved focus effect. A good source for
this is Track 14, The Nearness of You,
observe the studio ambience revealed by the piano. If your speakers do not reveal
the furthest corners of this room, sit up really straight to raise or slouch
down a little to lower your head at the sweet spot. If the room ambience
improves with your head slightly higher, the speakers are tilted back too much.
If the ambience improves with your head slightly lower, they are not tilted
back far enough. You should find a tilt angle where the sound just clicks where
the music really locks into both time and space. Just like pressing down on the
gas pedal to achieve a certain cruising speed in your car (pressing down too
much on the pedal makes you go too fast and not enough makes you go too slow),
so does the optimum tilt angle allow you to enjoy a more clearly defined
soundstage and a more purposeful sense of pace and rhythm.
Usually, the midrange driver in your speakers will be pretty
much in a direct line to your ears at this optimum toe-in and tilt angle are
achieved. Minor variations to this line achieve optimum clarity, focus, and
imaging. Once you have fine-tuned that angle, lock the feet in place and you
are all done.
Your soundstage should now be full and highly emotional
charged with life and energy. Reverberations should begin to take on a fading
effect that degrades into the distance beyond what you can see of the front
wall. If your arms were long enough, it’s as if you could reach through the
front wall and touch the distant corners. Typically, echoes in the upper right
and upper left extreme edges are impacted by these last few tweaks and those
changes can be again plotted on your paper. If you have a difficult time in
correlating echoes to depth, focus on these same extreme corner positions to
make these final adjustments.
Remember, you must decide the best speaker position for your
own musical preferences. There will always be a tradeoff between smooth bass
response and optimal soundstage size. My ears are more tolerant of bass bumps
and dips and more critical of soundstage sizing and inner detailing. You must
decide what you can tolerate and what you cannot and adjust your speaker
positions accordingly.
I hope that this seven-part series helped you to enjoy your
system even more than before and at the same time taught you a little about how
to listen to music. It amazes me when asking an audiophile, “So what
differences did you hear?” a long delay of utter silence results in the
inability to describe clearly what one’s emotions feel. Most people know what
they like when they hear it but have a difficult time putting that into words. With
patience and time you will be able to clearly enunciate and accurately convey
exactly what you hear and what you do not in any system. Once your speaker
positions are properly “dialed in,” a whole new world of enjoyment and
listening pleasure awaits. You may find yourself saying things like, “I never
heard that before…” or “Did you hear that?” or “Wow! That was amazing!” Keep
making small changes in all ways to complete your fine-tuning process. Oh yes, lastly,
remove the tape from your floor and the strings from your walls, turn off the
lights, and listen to what you’ve been missing!
Links to the entire series:
Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7
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.
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