Tannoy 6D 66D & 8D MID and High EQ Settings, Placement of the Speakers, Orientation R6D & R8D

MID AND HIGH EQ SETTINGS

RT60 Decay Time: An estimation of the RT60 decay time above 1kHz within the monitoring environment will help to set the mid and high frequency equalisation. Hard surfaces in general and particularly if close to the speakers will increase the amount of reverberent energy to direct energy above 1kHz (RT60 above 500mS) and may justify setting the mid or high EQ (or both) to -1dB. Absorbent surfaces in general and particularly if close to the speakers (RT60 below 200mS) will reduce the reverberant to direct energy and may justify setting the mid or high (or both) EQ to +1dB. In both cases the LF-Q may be adjusted to compensate the overall balance. If the monitor environment is well designed with a flat RT60 time of around 200 to 250mS then no LF-Q, mid or high EQ should be required.

Source Material: For prolonged sessions working on bright, forward or difficult news/location material where the content of material is being edited rather than control of the sound quality the full range of mid and high EQ can be used to prevent fatigue. This is a matter of individual taste and the EQ can be set accordingly. Alternatively, boosting mid and high frequencies can make decisions during editing easier with limited bandwidth material.

+10dB
0dB re 2.8v
@ 1 metre
-10dB									1 1 1 0 0 0
							1 1 0 0		0 1 1 0 0 0
							0 1 0 0		0 0 1 0 0 0
				1 1 1 0	1 1 1 0	0 0	0 0 0 0		0 0 0 0 0 0
							0 0 1 0		0 0 0 1 0 0
							0 0 1 1		0 0 0 1 1 0
									0 0 0 1 1 1
10Hz	20Hz	50Hz	100Hz	200Hz	500Hz	1Khz	2kHz	5kHz	10kHz	20kHz

6.0: 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 near-field speakers, and the operating environment, in order for you to gain the maximum performance from the pair sitting in front of you.

6.1: ORIENTATION (R6D & R8D)

Two-way speakers have a correct orientation for the serious listener. Two way systems use a separate 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 apparent acoustic center of each device and the plane of the baffle at the crossover point. By stacking the woofer and tweeter vertically, we minimise the problems caused by these physical offsets. The near-field listening conditions magnify the effects of the driver offsets, so we really need to optimise 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 metres away. Need proof? Put on some music, not loud, and get really close, about 500mm (20") 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.

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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 (2.0kHz to 3.0kHz), where we are most capable of recognising frequency/phase response deviations.

In the diagrams below we have a graphical representation of the speaker systems operating at the crossover point where both high and low frequency drivers produce the same output level. The first one shows a pair of two-way loudspeakers lying on their side. Note that each driver is producing sound, and because there is a physical distance separating them on the baffle, there is also a time difference separating the drivers, and the result is what you see here. Around the crossover point, the speaker will produce numerous lobes, producing changes in midrange sound character as you move across the horizontal listening plane.

HORIZONTAL

Stereo occurs from left to right, so that is the listening plane in which we try to minimise the changes in physical/time offset between the woofers and tweeters. And we have to be honest, it’s not perfect, the driver offset is still there, but by stacking the woofer and tweeter vertically on the baffle we can give the mix engineer the widest range of movement in the horizontal plane. You can roll your chair across the length of your mixing console and not change the relationship between the woofer and tweeter (just don’t bob your head up and down while you do it).

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