Marchand Electronics XM66, XM9, XM44, XM16, XM26 User Manual
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User’s Guide
Electronic Crossover Network
XM66 Variable Frequency
XM9 24 dB/octave
XM16 48 dB/octave
XM44 24/48 dB/octave
XM26 24 dB/octave Tube
XM46 24 dB/octave Passive Line Level
XM126 24 dB/octave Tube
Marchand Electronics Inc.
Rochester, NY
(585) 423 0462
www.marchandelec.com
The electronic crossover is used to drive individual loudspeakers for separate portions of the
audio frequency spectrum. A two way crossover is used for bass and high frequency speakers. A
three way crossover is used when driving bass, midrange and high frequency speaker. The signal
from the preamp is passed to the electronic crossover network. The outputs of the crossover
network are then connected to the power amplifiers for the individual loudspeakers as in Figure 1 .
A typical configuration like this might have the crossover frequency set at 300 to 1000 Hz,
depending on the type of loudspeakers used. When used with subwoofers as low frequency
speakers, the typical crossover frequency is around 100 Hz. The range is 50 to 150 Hz for most
subwoofers. When the crossover frequency is below 100 Hz there usually is no stereo information
present from the sound of the subwoofer, and a common subwoofer can be used. Figure 3 shows
how to use the crossovers with a common subwoofer. The sum switch on the crossover front
panel causes the outputs of both low pass channel to be summed together. Both outputs will have
the same summed signal on them, and either one can thus be used to drive he common
subwoofer. The advantage of a common subwoofer is more than just cost. Because there is only
one subwoofer present, often a larger unit can be chosen, with an extended bass range.
It is also possible to drive more than two speakers per channel. Figure 2 shows a three way
system with woofers, midranges and tweeters.
Choosing the crossover frequency and slope
At frequencies below the crossover frequency the signal will go to the low pass outputs. At
frequencies above the crossover frequency the signal will go to the high pass outputs. There is a
region around the crossover point where the signal will come out of both the high pass output and
the low pass output. For he crossover networks with a slope of 24 dB/octave (XM6, XM9 and
XM26) the width of this region is about 1/2 octave. For the XM16, with a slope of 48 dB/octave,
the width of this region is halved to 1/4 octave.
Figure 4 shows the frequency response of the 24 dB/octave crossover networks (XM6, XM9 and
XM26). The figure is drawn for a crossover frequency of 100 Hz. For other crossover frequencies
© 2017 Marchand Electronics Inc. www.marchandelec.com.
2
Amp
Amp
Left
High
Left
Low
C
r
o
s
s
o
v
e
r
Left High Out
Right Low Out
Right High Out
Right
High
Right
Low
Left Low Out
P
r
e
a
m
p
Right In
Left In
Left Out
Right Out
Amp
Amp
Figure 1
Two-way system has separate amplifiers for high and low range speakers
the same figure applies, with the frequency scale scaled. Note that both the high pass response
and the low pass response are down exactly 6 dB at the crossover point of 100 Hz. This means
that at this frequency the amplitude is exactly half. Adding the high pass and low pass together
sum to unity. As a matter of fact the sum of the high pass and the low pass response is unity for
all frequencies. This is why the filter is called a “constant voltage network. It is also called a
Linkwitz-Riley network, after the two writers who first introduced this concept in the audio world.
The frequency response of the phase of the 24 dB/octave network is shown in Figure 5. The
frequency response of the phase is the same for the high pass and the low pass outputs. Note
that at the crossover point the phase shift is exactly 180 degrees.
Figure 9 shows the frequency response of the XM16 crossover network. This network has a slope
of 48 dB/octave. Figure 8 shows the phase response of the XM16 crossover network. Note that
the phase shift of the XM16 is twice that of the other networks. The XM16 does not have a
damping control.
The choice of the crossover point is a difficult one, and often some trial and error is needed for
achieving best results. With the 24 dB/octave crossover networks a good rule of thumb is to set
the crossover point at least one half to one octave away from the cutoff frequency of the speaker.
Thus a satellite with a cutoff frequency of 50 Hz at the low and that is used with a subwoofer
requires a crossover frequency of 75 to 100 Hz. The subwoofer should then also have a range
extending half to one octave above the crossover frequency. In this case, if 100 Hz was chosen,
the subwoofer should have a range of at least 200 Hz.
© 2017 Marchand Electronics Inc. www.marchandelec.com.
3
Amp
Amp
Left
Mid
Left
Woofer
C
r
o
s
s
o
v
e
r
Left Mid Out
Right Mid Out
Right High Out
Right
Tweeter
Right
Woofer
Left Low Out
P
r
e
a
m
p
Right In
Left In
Left Out
Right Out
Amp
Amp
Amp
Right
Mid
Left
Tweeter
Right Low Out
Left High Out
Amp
Figure 2
Three-way system has separate amplifiers for tweeters, midrange and woofers
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