Threshold pcx brochure

Page 1

PCX

Threshold

model PCX
electronic
crossover

The Threshold PGX provides the serious music
listener with an extremely flexible. state-ot-the-art
frequency dividing network. It is characterizedehy :
very low distortion and exceptional dynamic
performance. Through application of optimum filter
slopes and 0 characteristics the 90X virtually
eliminates driver activity and interference outside
the selected passband. Unlike conventional sharp-
slope filter designs the PCX will. nevertheless. still
sum llat within 0.5 dB without phase inversion.
This amplitude and phase accuracy assures
maximum performance from the associated
loudspeaker drivers and allows reproduction,

intact. of all the available musical information.

Page 2

Threshold

model P_CX
electronic
crossover

THE THRESHOLD PCX IS SUITAILE FDR
BI-AMPLIFICATION. OR TRIAMPLIFICATION THROUGH
THE USE OF TWO UNITS. IT WILL ALSO PROVIDE THE
APPROPRIATE SIGNAL FOR STEREO OR SUMMED-MDNO
SUOWOOFER SYSTEMS AND PERMITS "BRIDGING" OF A
STEREO AMPLIFIER FOR USE AS A SUMMED-MOHO LOW
FREQUENCY DRIVE. SEVENTEEN CROSSOVER POINTS
HAVING 18 dB PER OOTAVE SLOPES ARE USER
SELEOTAOLE IETVIEEN THE RANGE OF 75 Hz THROUGH
3.602 H1. A HIGHER RANGE IS AVAILADLE ON SPECIAL
RDER.

Despite the higher cost and complexity at multi-
amplitying a loudspeaker system dedicated musrc lis-
toners. and state-ot-the-art manuleclurers. continue
to employ this concept in top quality componentry.
This Is because it is acknowledged to provide a level
or performance significantly superior to Single empti-
lied systems Now Threshold makes available a highly
sophlslicated. extremely llextble electronic crossover
0! great accuracy that Will enable multi-emptilication
in a wide variety ol systems and applications.

In essence. an electronic crossover. such as the
Threshold PCX. allows the passive. highly reactive
elements cl 3 loudspeakers Iiller networks to be by-
passad. Instead. each loudspeaker driver is directly
connected to an amplilier dedicated to its particular
lrequency range. There are many perlormance ad-
vantages associated Wllh the use at a Threshold PCX
in this manner that allow retrieval 01 musical inlor-
mation otherwise lost. masked. or distorted

Systems usrng the Threshold PCX are tar less subiect
to intermodulalion etlects. This term at distortion is
generally a problem when power handling compo-
nents must deal with high and low trequencies simul-
taneously. In conventional systems IM distortion
occurs in the power amplilier and loudspeaker cross-
overs. where high lrequency inlormation must ride on
low lrequency wavelorms. This causes the creation
ol non-muSical lrequency components called side-
bands." These are greatly reduced through use at the
Threshold PCX by separating high and low lrequency
components ol the musrc before amplification,
Application ol the Threshold PCX allows a direct and
intimate coupling between the dedicated amplifier
and driver that cannot be achieved through a loud-
speakers passrve litter network. This enables control
at the loudspeaker driver by the lull damping lactor
available lrom the amplifier. lowering harmonic dis-
tortion products while improvmg tran5ient response.
When an amplilier is interlaced to the driver through
the loudspeakers highly reactive crossover network
the damping laclor seen by the amplilier can drop to
as low as 1 at various Irequenctes. resulting in poor
driver control.

The Threshold PCX will also enable an increase in
dynamic range to about lwtce that at a conventional
passwe system. assuming the same amplilier power
in each case. This eltect is tound typical 01 systems
being lrequencydivided in the range 01100 Hz to 1000
Hz and is the result 01 separation at low and high he-
quency transients which are olten at about the same
voltage amplitude but which are not riding on each
other in an actively crossed over system. As an ex-
ample, the dynamic range delivered by two 200 watt
bl-amplilied loudspeaker channels (a total 0! 40!)
walls) is roughly equivalent to the same loudspeaker
passwely crossed over when driven by two 400 watt
channels (a total 01 800 watts)

The Threshold PCX is the linest and most tlexible in-
strument ol its type. Extensive computer analysis and
listening sessions wtlh a variety ol loudspeakers went
into optimising the crossover slopes and 0 factors.
Special butter circuitry was developed to drive the low
impedance networks required to achieve these char~
actertstics. As has been the case With all Threshold
components an absolute minimum number ol active
elements are used in the most simple and direct audio
Circuit topology. Complexity is reserved for support
Circuits that do not carry eignal inlormation but are
used to shield and maintain the audio carrying do.
Vices in linear operating modes. The audio gain de-
vrces. themselves. consist ot discrete. direct coupled
JFET. MOSFET and bipolar devices. The PCX Iiller
networks are designed to cut oil rapidly. minimizing
nonlinear driver activity and overlap, and yet still re-
sum within a Iew percent oi Ilal without phase
inversion.

Each PCX is built to the high standards 01 craltsman-
ship and linish lor which Threshold has received
world-Wide recognition. All circuit components are se-
lected lrom among the linest available. The Circuit
board is military-grade glass-epoxy wrth circuit paths
consisting at a copper base lollowed by nickel. then
gold plating. All internal connections are hard sot-
dered by hand. Metal lilm and vrirewound resistors are
used throughout. and only the highest quality trim and
silver mice capacitors are used in the signal path. The
gold plated signal connectors have machined Tellon
Insulation and are manutactured exclusively Ior
Threshold. Their spectal destgn and construction
assures a quality ot electrical intimacy equivalent to
smaller! "exotic" connectors while still maintaining
the convenience at an RCA lormat.

CROSSOVER POINTS ARE USER SELECTED THROUGH SUBSTI-
TUTIOH OF PRECISION RESISTOR ELEMENTS CONTAINED IN
STANDARD 16 PIN DIP ASSEMBLIES. THESE ARE HELD III LAB»
ORATORV GRADE "ZERO INSERTION FORCE" SOCKETS. THE
LEVER-LOCKING SOCKETS ASSURE POSITIVE ELECTRICAL
OOHTADT WHILE ELIMINATING ANY POSSIBILITY OF STRESS
TO THE DIP ASSEMBLY PINS. EVEN THROUGH REPEATED
REMOVAL AND NE-INSERTIDN.

TECHNICAL DATA

DESCRIPTION
Dual channel dual passhand electronic crossover

FREQUENCY RESPONSE

Low pass section dc to cutott slope initiation High pass sec»
tian: cutplt slop: entry to i00.000 Hz,

TOTAL HARMONIC DISTORTION

No greater than 0 01% 20 Hz lhrough 20.000 Hz

CONTROLS

Separate high pass and low pass tiltci level controls tor each
channel

AVAILABLE CROSSOVER POINTS

17 between lite range pl 75 Hz to L602 Hz (17 between the
range at 750 Hz to 15,020 Hz available on specral ordoii

FILTER SLOPES

18 at! par octave

REDOMBINATION CHARACTERISTICS

Amplitude accuracy liat witnin : 0.5 08 High pass filter
uhase non-invortep Low pass tiliei phase: non-inverted

OUTPlI'IS

Separate high pass and low pass tiller outputs tor each chan-
nel Normal and invertno polarity summed iL . Ri low pass
him outputs

IMPEDANCE
lhplll 20.000 Ohms
Output 1.500 Ohms. nominal

DIMENSIONS AND WEIGHT
PCX

Width at lacaplate: 19 inches

height at laceplate: 2 75 inches (add 0.25 mm loi teeti
Depth behind laceplale 6 5 inches ill) and at connectdisl
Weight 4.5 pounds

POWER SOURCE MODULE

Width 5.125 inches

height: 1 75 inches (add 0 25 inch Ior teetl

Depth 6 inches.

Weight 2.5 pounds

Threshold
Corporation

12919 earhart avenue
auburn calllornla 95603

threshold components are supplied with a IIITIITOO ninety-day
warranty covering parts. labor and surlace transport to and
hunt the lactory Optional THREE VEAR extended and translu-
abla coverage is available at no cost through return at the
Extendtd Warranty Registration Card accompanying every new
threshold product

Because Threshold is constantly researching new technologies
and materials the option is resrrvcd to incorporate OBSIOII MOO-
ilicatiotls into ongoing production Without notice or obligation

THRESHOLD. STVLIZED "T AND STASIS ARE REGISTERED
TRADEMARKS 0F THRESHOLD CORPORATION

pririiooiiiUSA