Orientation - Tannoy Proto-J Reference Manual

3.0 PLACEMENT OF THE SPEAKERS
Now here's the truly critical stuff. Speaker placement and the listening environment can completely
compromise the performance of any loudspeaker, no matter how much it costs. It is important to
understand some limitations of nearfield speakers, and the operating environment, in order for you
to gain the maximum performance from the pair sitting in front of you.

3.1 Orientation

Two way speakers have a correct orientation for the serious listener. Two way systems use a sepa-
rate woofer and tweeter mounted in a vertical line on the baffle. There is a fixed vertical distance
between the centre of the two devices on the baffle, and there is fixed distance between the appar-
ent acoustic center of each device and the plane of the baffle at the crossover point. By stacking the
woofer and tweeter vertically, we minimize the problems caused by these physical offsets. The near-
field listening conditions magnify the effects of the driver offsets, so we really need to optimize the
speaker orientation. When you are very close to a speaker system, vertical head movements are
significant because your movement represents a large change in angle of arc, and therefore the
number of degrees above and below the axis (that's the line between the woofer and tweeter). In
other words, bob your head up and down a few centimeters within a metre of the cabinet, and your
ear moves through a larger angle relative to the speaker axis than it does with the same vertical
motion 4 or 5 meters away. Need proof? Put on some music, not loud, and get really close, about
20" (500 mm) away. Move your head up and down now, and you can actually get the musical image
to break into a separate high frequency and low frequency source. This is a wildly exaggerated
example of what we're talking about. It isn't that bad out here in the normal listening position, but the
variations are still there.
All two way component systems have to live with some listening position dependent compromises at
the crossover point. The crossover frequency of all of these small systems falls into the center of the
midband (2.0 kHz to 3.0 kHz), where we are most capable of recognizing frequency/phase response
deviations.
3' - 1 m
10 deg. @ 3 feet - 1 meter
12' - 4 m
2.5 deg. @ 12 feet - 4 meters
7" - 18 cm
7" - 18 cm