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3
DESIGNS AND FEATURES
Mounting
the 2X-4
This section describes the design and features of each
component in the Punch AUDIO
phile
System.
The 2X-4 Crossover is designed to be the “link” between
the ND4 neodymium tweeters, and RFA-44, 54 and 64
midrange/woofer speakers. This compact 2-way cross-
over is designed to conform to the following criteria:
• 2-Way Crossover network centered at 4 kHz.
• Uses Linkwitz-Riley 2nd order transfer function (12 dB/
octave).
• Additional tweeter filtering uses a series notch filter
centered at 1500 Hz to minimize the tweeter's reso-
nance peak.
• Also included is impedance compensation equaliza-
tion (Zobel network). This flattens out the gradual
impedance rise above 10 kHz.
• Tweeter protection provided through a special com-
pression circuit.
This compression technique in the crossover uses an
array of two lamps wired in parallel, whose function is
to monitor the input power to the tweeter. When it sees
a threatening increase in input voltage, it will increase
the resistance. This technique is fast, and virtually
undetectable to the listener. Other manufacturers'
tweeter protection is done via circuit breakers. This
method drastically reduces tweeter output, which is
very noticeable and distracting for the listener.
• Small size is accomplished by using inductors wound
on specially designed ferrite bobbins.
Attaching wires to the 2X-4 is accomplished with the use
of silver plated “screw-lok” terminals to secure both the
input and output speaker wires. The 2X-4 accepts wire
sizes up to 12 gauge.
The 2X-4 is mounted to relatively flat surfaces with sheet-
metal screws inserted into the mounting holes on either
side of the enclosure.
2X-4 High
Pass and
Low Pass
Crossover
Input and
Output
Connectors