Mono & Mirror Method of Tuning. Less Foundational & More Mechanical.

Two weeks ago we talked a bit about the loudspeaker/room/listener triangle and how the qualities of one effect the other, how changing the qualities of any one effects the whole of the triad. Last week we touched on the basic qualities of a note—attack, sustain and decay—and how the objects forming the triad then interplay with the waveforms were recognized. These two articles, though brief, should help us see more clearly how to get the sound we want our playback system and the room that supports it. Today we shift from the foundational to the mechanical and introduce the Zu mono-and-mirror method of tuning.

Zu’s mono and mirror speaker position tuning method is efficient, yielding excellent results without days of fiddling. With speaker placement tuning you are affecting how the wavefronts initially hit the primary listening position, and also how the room’s acoustic properties affect and interplay with the sound sources, the speakers. Though the guidance is geared for 2-channel rigs, it is also useful for multi-channel as the front left/right are the foundation on which the other channels hinge. Method assumes room and layout accommodate a symmetric left/right speaker placement. Key points are:

- Tune just one speaker, then mirror its mate
- Use mono recordings, or punch-in that mono button, you need to hear the whole of the recording
- Tune largest wavelengths first - BASS
- Tune MIDRANGE after bass has been tuned
- Tune TREBLE after the mids have been tuned

In most rooms there’s one loudspeaker position that is framed with more wall space, this is the loudspeaker you will tune. Once tuned you will simply measure and mirror the other. If your room is symmetrical start with the left.

Turn off or disconnect the speaker that is not being tuned. If disconnecting, do so on the amp-side to reduce the chance of shorting the connectors, or safeguard the speaker-side bare contacts from touching if disconnecting them at the speaker (ZuB3 connector users need not worry, your free to hot-swap.)

First, tune for bass. No matter how good you get the midrange and treble sounding, if you don’t get the bass right there’s little foundation to anchor the rest—assuming you don’t exclusively listen to trumpet played in a vacuum. Bass tuning is big strokes, moving the speaker a foot or three [0.3 ~ 1.0 m] with each position sample.

Second is tuning of midrange where you are working with smaller moves, six inches [15 cm] this way or that, then three inches [8 cm], then an inch [3 cm] or so.

Third is tuning the treble, where it’s more about toe and lean-back, maybe with some subtle nudging of the position, half inches and less [≤13 mm].processing.

Move listen, move listen... taking mental note of changes in sound. Note that moving the sound source also changes how the room reacts. You should only have to move the loudspeaker three or four times to get the bass dialed in, half dozen moves on the mids, and maybe the same for treble. If you are struggling start over with bass. If still struggling, give up on that side and try the other side. Take note of the differences. The devil’s triangle is not a drinking game. Experiment with your speaker placement, your room, where you sit… the changes and improvements to be had are not subtle.

Let's tune for bass and see if we can make a performance improvement. Select recordings with large amounts of low frequency information; dramatic pipe organ and dance music work as do test recordings that have warbled low frequency tracks (20 - 100 Hz range). But do not use test tones exclusively, your brain needs some transients for contexts to do its best work. Test tones can and often do play a roll, but that steady-state sine, triangle and square-wave signal prove difficult for human brains to interpret without some transient counterpoise. If you don’t have time for several cuts and types of bass, select some modern disco track with a drone influence to make fast work of long wavelength (bass) tuning.

Here we go. Loudspeaker is where it is, pointing into the room perpendicular to the front wall, playing at a moderate level (only the one loudspeaker should be on); walk over and kneel down next to it. Kneeling will put your head in the seated listening horizontal plane and allow you to hear how the loudspeaker is influencing, and influenced by, the room. In nearly all rooms, the two positions, i.e., loudspeaker and sweet spot, have reciprocal acoustic properties, listening in both zones will help you better map the room/speaker relationship and resulting sound qualities.

You’re kneeling next to the playing loudspeaker, now move your head to either side and back and forth of it, say a foot or two [0.3 ~ 1.0 m] in each axis. Listen to the qualities of the bass, does it sound woolly and muddy behind the loudspeaker? Is the bass more defined a bit to the left or right? If the bass sounds better a bit to the left, move the loudspeaker to that position, and then listen again. Remember, moving the sound source also changes how the room reacts. With each move you should again move your head about. You should also walk back and sit or kneel in your listening position, listen for the changes there, swiveling your head about as you did at the speaker, listening to the broader sweet-spot zone.


You should get the bass sounding pretty good with two, three or four speaker position changes. When it sounds pretty good call it and move on to midrange tuning. Good enough in this case is usually way better than you realize. Listening to just one speaker seems to focus our hearing powers, and reveals issues in the room, loudspeaker, system, recording... that evaporate, or nearly so, when you mirror the mating speaker and light things up in stereo.