Speaker Placement — Tone

The following focuses on tone and not stereophony and addresses the loudspeaker’s relationship with the room—a quick article to help you get great sound out of your system and room.

The three main aspects of getting good sound out are: the recording, the playback system and the room the system resides. Which is most important? Well, it depends what’s important and what’s desired but the argument can be made for each for title of greatest significance. Most any room will have regions wherein the sound will be open and full. Direct radiating speakers like Zu Omen and Soul Supreme will sound best to the majority of people when placed in these areas; same holds true for house parties where you have your buddy Dan playing guitar and singing.  

TONE FIRST

There are two main areas of fidelity if bandwidth, dynamic range and group delay (more or less timing) are assumed; and as dynamic range, bandwidth and group delay are largely set by the system, the user can’t really tune these elements anyway. Tunable elements are: tone (as used by Helmholtz and further defined by guitarist’s the world over) and the soundfield/stereophonic image (“soundstage” as is the hi-fi jargon). Stereophony will be addressed in the next post. Again, you start with tone, the foundation.

The room. How and where the loudspeakers excite the room and how the room reacts is relative to the type and source of excitation and room reactance. These are a function of boundaries (walls, floors, etc.), boundary properties (building materials—mass, compliance, Q, damping, texture and structure), area impedances (shape, volume), diffusion and absorption (furnishings, people, flooring, etc.), source and type of wave excitation (loudspeaker design and placement), resonators (closets, forced air ducting, hallways, etc.), even atmospheric pressure and humidity, though very minor, will influence your sound. While these points are outside the word count of a blog post it is helpful to have the big picture of your room in mind as we get into it.

With your loudspeakers initially positioned for visual appeal and livability (you and yours need to live with your playback rig) you can now begin tuning the loudspeaker placement, tone first. This involves three major steps plus elevation and firing axis. In sequence they are: bass, mid’s and treble. If you can’t tone-tune your system within an evening, or you find the concepts difficult, do yourself a favor and reach out for help. In addition to calling Zu, there are a lot of good acoustics guys in pro audio; in every city there are a handful of really good guys, track ‘em down.

ONE LOUDSPEAKER TUNING

Traditional musical instruments are tuned around the concept of tone, and there is no “stereo” in them. Designer, builder, tuner, player... are all keyed-in on the instrument’s tone. And if you can’t get tone or the recreation of it, little else matters—to the majority anyway. So if you want to hear what Mike Watt is doing with his 1963 Gibson EB-3 bass guitar, or tell it apart from a 1966 Fender Mustang (assuming the same amp) focus on building tone in your room and system and forget stereophony, which includes anything more than one channel, at least for now. 

Focus and tune just one loudspeaker. Which? The loudspeaker that will be most impacted by the room, usually the one that is most framed by wall area, the side lacking a door or whatever. You will tune this for tone, with the matching loudspeaker disconnected from the amp. Once you have tuned this one channel for tone you will then get the measuring tape out and simply mirror the mate and presto, you have tone, texture, and stereophonic magic and without wasting a bunch of time getting it. 

TONE IN BASS

Select a recording that is big on tone, something monaural, with a big full sound, possibly with a baritone vocal. Don’t use test tones. Steady-state sine, triangle and square wave signal’s prove very difficult to interpret. Full, tone rich mono recordings (or engage your mono button/setting if you have it) will enable the listener to make fast work of fine tuning. With the one loudspeaker playing at a moderate level, initially positioned where it looks good, walk over and kneel down next to it. Kneeling will put your head/ears/chest in the seated listening plane and allow you to hear how the loudspeaker integrates with the room, specific to you, with emphasis on the seated elevation. Now move to either side of, and back and forth of the loudspeaker, in big dramatic sweeps. After all it’s big bass waves we are listening to here. Envision the size of full on North Shore surf, moving at the speed of sound, impinging, disrupting, moving through and bouncing off all the boundaries in your home. Yes, bass waves are big. Listen to the fidelity of the bass, does it sound woolly or muddy right behind the loudspeaker? Is the bass more defined to the left or right? If the bass sounds better to the left move the loudspeaker to that spot and listen again. Remember that moving the loudspeaker also changes the room/speaker reactance—the target is moving. You should only have to move the loudspeaker three or four times to get it sounding as you like. With each listen and move, you should also listen in your center seat and try and confirm and corollate your observations at both positions. Complicated rooms can be further mentally modeled by walking about the whole room, noting nulls and anti-nodes (peaks) within bass octaves. If you aren’t hearing much, move on, you could have it nailed or have a great sounding room. 

For problem rooms there is also a good technique referred to as listener mirroring. Place the one loudspeaker where you want to listen, playing in the direction you want to place it, then play the bass heavy material and listen in the general area of the shortly to be loudspeaker spot; the area and distances from side walls that sound best will very likely be the best place to plop down your speaker. 

TONE MIDRANGE & TREBLE TUNING

Once the bass is sounding good we can now work on getting natural, vibrant midrange and treble. Before you begin, it’s important to understand these wavelengths. Midrange tuning while similar to that of bass, is a task of inches (decimeters) rather than yards (meters) and treble a matter of half inches (centimeters) and loudspeaker firing axis. Even though midrange and treble changes can be heard at the “being positioned loudspeaker” it’s helpful to have a friend position while you listen in the seating area. 

Continue with the same loudspeaker room-tuned for bass (you will simply mirror its mate and connect the second one as the final step). Play a familiar less than bass heavy recording, preferably monophonic or with your mono button engaged, start tuning for mids and highs. Move the loudspeaker toward the closest wall, in increments of a few inches (5 - 10cm). While moving the loudspeaker, the in-the-listening area observer (and possibly the person positioning the loudspeaker) should notice midrange color and presence transition from masked to open and intimate. There may be several spots within the good sounding bass area that have good presence, go with the widest point (closest to the wall) for an expansive and engaging soundfield/stereo image once you mirror the mate and run both channels. Don’t worry about center focus, Zu loudspeakers have no problem doing expansive and focused stereophonic soundscapes due to their tight matching of pairs.

With a midrange position selected it’s time to work on the treble. This is usually as simple as rotating (toeing-in) the loudspeaker to face a bit behind, directly at, or in some cases just in front of the seated listener. Now listen again for openness and intimacy, minor placement adjustments and face angle (toe-in) may be necessary. If the sound is a bit too treble forward rotate the loudspeaker to focus behind the main listening area. If still you have a bit too much treble emphasis [reasons] rotate the loudspeaker out a bit further. Experiment. 

Another area to pay some attention to is the loudspeaker firing axis, loudspeaker elevation, and seated elevation. Canting (tilting) the loudspeaker will change the sound as well. While Omen, Soul and Soul Supreme do a great job of creating a very stable and large soundfield (staying together and uniform as you sit, stand and move about your room and home) you should experiment with this. First using your legs, squat style, move your head through the vertical soundfield, notice the changes. You can adjust that sound of the sit/stand differences with the adjustable feet on the speaker, a bit of lean-back might be just what you are looking for. Experiment.

Take your time positioning the one “playing” loudspeaker. It’s much easier to hear what’s happening from a mono recording played through a single speaker due to the much less complex soundfield. Seriously, you will have a much easier time drawing reliable conclusions on what’s going on with the room and sound when not working within a stereo soundfield. Get the one channel sounding good, and when you’re satisfied simply get the measuring tools out and mirror the mate and hook up the second loudspeaker (black to black, red to red). Enjoy the bliss.