MartinLogan Monolith III user manual IIIx Operation, Crossover Settings, Bass Contour Controls

IIIx Operation

Crossover Settings

Before you do any formal listening, you must set a pair of switches in the crossover. However, if you are using identical amplifiers (i.e. same make and model) for the high and low-pass sections of the Monolith, you may use the factory settings and skip this step.

On the back panel of the crossover there are two cut-outs that allow you to access two red dip switches. These switches adjust the low-pass gain so that you may balance the gain between the high-pass and low-pass amplifiers if they have different gain characteristics. We have even enclosed a red "dip stick" tool to assist you with this procedure.

The following formula will help you calculate the relative gain of your amplifiers:

optimal setting is to locate the microphone of a spectrum analyzer in the room near your seating position, play pink noise through the system and begin to observe the relationship of the electrostatic transducer and the subwoofer at the crossover point which is 125 Hz. Your gain settings will be correct when the display is flat and consistent. You want the energy below 100 Hz to be roughly compa- rable to the energy above 100 Hz. If you now have reasonable tonal balance from 60 Hz onward to 200 Hz, then you have the optimal frequency balance at the crossover point.

Keep in mind that specifications and equipment can determine the best place to begin, but your ears are the most critical instruments available. Listen to music and adjust for your best personal balance.

Bass Contour Controls

You will notice that there are two controls on the front of the MONOLITH IIIx CROSSOVER. The left control is labeled frequency and the right control is labeled boost/cut. (See Figure 6.) These are a very accurate and precise pair of controls that allow you to adjust your speakers output in the most problematic area of music reproduction; the bass region.

Your Room and Bass

Today we are finding that all elements in the audio chain can and will affect your system's performance. Of these elements, your room is the worst offender. Once the precisely tailored musical signal is launched from your speaker system, your room then has

Amplifier gain is defined as:

20 log
	(Rated Output @ 8 ohms) x 8
	Input Sensitivity

At right, in Figure 5, is a list of switch settings to help you select the proper gain switch settings.

As you detent the switch towards the ON position, you are engaging that switch. Each switch detent away from position “4” either increases or decreases the output of the low-pass amplifier. In order to properly engage a switch, you need to have all other switches in the OFF position. If the high-pass and low- pass amplifiers are identical or have the same gain, the system is designed to operate with both switches set to “4” (Position “4” represents 0dB of gain).

If equipped, the best way to obtain the

					its way with that
					musical signal;
					particularly with the
					larger wave-
ON		GAIN	ON	GAIN	lengths of the
					bass region. Your
None		-6.0 dB	*5	+1.5 dB	room will enhance
					and cancel certain
*1		-4.5 dB	5&2	+2.0 dB	frequencies,
*2		-3.0 dB	5&3	+2.5 dB	making a perfect
2&1		-2.0 dB	*6	+3.0 dB	speaker look less
*3		-1.5 dB	6&3	+3.5 dB	than perfect in the
3&1		-1.0 dB	6&5	+4.0 dB	best of instances
*4		0 dB	*7	+4.5 dB	and like a jumbled
					mess in the worst
4&1		+0.5 dB	7&6	+5.0 dB
					of instances. The
4&2		+1.0 dB	*8	+6.0 dB
					front panel
					controls of the
Figure 5: Low-pass attenuation switch settings.					crossover can be
NOTE: Start with "*" settings first, then fine					used much like an
	tune using the intermediate settings.				accurate bass/

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