Electro voice p 1250 brochure

Page 2

Operating Voltage:
120 V. 60 Hz ac
Power Consumption (both channels
operatlng In dual mode. II power),
4 Ohms:
550 VA
Dimensions, (us Figure 1)
Height:
88.1 mm (3.5 in.)
Width:
483 mm (19.0 in.)
Depth:
426 mm (16.8 in.)
Color:
Dark gray
Net Weight:
17.0 kg (37.5 lb)
Shipping Weight:
17,e kg (39.3 lb)

DESCRIPTION

The Electra-Voice P1250 PrecisionSeries' am«
pfifier is a very-high-qualiiy power amplifier
designed to elicit maximum performance and
sound quality lrom any speaker system. Its
ultralow distortion. powerful amplifiers and
unique processor section ensure that any
speaker system will sound its very best.

Each channel at the P1250 delivers more than
350 watts continuous average power into
8 ohms. 500 watts into 4 ohms and 600 walls
into Zohms over the full audio frequency range.
in the bridge mode. the amplifier can deliver
more than 740 watts into 8 ohms and 1.300
watts imo 4 ohms at less than 1% THD. The
power supply, with its large toroidal lranslormer.
gives the amplifier impressive headroom and
current output.

The P1250 contains 20 high-power output deA
Vices with 5.000 watts ol dissipation capability.
These devices are protected irom overheating
by two. three~speed. temperature-sensitive fans.
The tans are quiet enough to permit use oi the
P1250 in noise-sensitive applications such as
recording studios and houses oi worship.

The output devices are mounted to a massive.
extruded-aluminum heat sink thatts engineered
to minimize thermal gradients and allow the
amplifier to operate saiely into low-impedance
loads The output devices have a maximum
lunction temperature oi 200 "C (392 F). so high
operational len'lperatures present no problems.
The output devices are mounted directly to the
heat sink without mica insulators to ensure
better dissipation oi heat

Many electronic circuit innovations exist in the
P1250. Among the most novel oi these drwils
Is the Dual Diiierentlal Discrete Topology.
This circuit is pan 0! the tram end of the ampli-
fier. uses discrete electrical componean in-
stead oi integrated circuits. and is fully sym-
metrical lor both polarities.

The built-in processor utilizes Electro-Voices
patented Dynamic Signal ProcessingI circuitry
along with unprecedented speaker matching
and protectlon. The Dynamic Signal
Processing" circuitry ensures that transient
response and phase distortion in the speaker is
minimized. resulting in dynamic, poweriul bass
and clear. three-dimensional highs. The pro-

cessor controls allow you to select the enclo
sure tuning (12 or 24 d8 per octave) as well as
adiust the notch" frequency which closely cor-
responds to the 3-dE-down point ol the enclo-
sure (60 Hz. 43 Hz. 26 Hz). The processor also
has circuits that help prevent severe amplifier
dipping and can limit peak power led to the
loudspeaker if high power levels are main-
tained tor an extended period.

The F1250 has sophisticated protectlon cir-
cuits that guard it and the load from problems.
Protection circuits guard against overload.
overtemperature. shorted outputs. radioire~
quency inlerierence and dc iaulls. The output
devices are protected against damage lrom
reverse ieedng oi electrical energy (back EMF)
and are switched on via relays to avoid tran-
sients which could damage speakers.

The P1250 has built-in limiters to protect speak-
ers from the deleterious eilects oi amplifier
clipping. The lirniter's action is governed by
very soph'sticated input/output comparators
which have acoustically optimized time con-
stants to preserve the integrity oi the source.
The limiters time constants are swrtchable last]
slow. so the limiter may be matched to the
application for which the amplifier is being
used.

The P1250 has built-in switchable hlgh- and
low-cut filters. These filters attenuate intrasonic
and ultrahigh-irequency signals. preventing
them irom being amplified; this allows more
eiiective use of the amplifiers power and adds
a measure 01 load protection. These filters are
aq'ustable (15 Hz or 31 Hz) and may be turned
off ior use in applications utilizing irontend units
llike crossovers orequallzers) which have these
filters built-in.

Amulliiunction display keeps the userinforrned
oi the operating status 01 the ampllfier. Sepav
rate LED displays ior each channel show power
on. input signal present, output signal, limiter
on. protection active and processor on.

The P1250 has electronically balanced XLR-
type input and output connectors that allow
easy. problem-heeconnections and signal rout~
ing. The P1250 has an input routing switch that
allows selection at either normal dual-channel
operation. or parallel mono operation, which
routes an input to both channels but still allows
for independent level control. The P1250 also
has a consmnt-gain option which. with input
level controls lull clockwise. provides a 26~dB
voltage gain that is identical to that oi all
EIectro-Voice Precision Serlesm amplifiers in
the constant-gain option. regardless oi power
rating. ThII makes it possible to exchange
amplifiers oi diiierenl power ratings without
upsetting delivered sound pressure levels or
spectral balances.

The P1250's output connectors are protes-
sional Nautrik Speakon' connectors which pro-
vide a sturdy, reliable connection and allow use
oi heavy wire lor loss-tree signal transmission.
There are separate output connectors iorchan~
nets A and B. and for the bridge mode. The
bridge-mode connector is sealed with a plastic
cover to prevent connection errors.
i

To prevent ground loops from occurring. the
P1250 is equipped with a ground-lift switch.
When the amplifier is operated in a rack with
units at diiierenl ground potential, the switch
may be adjusted to eliminate hum.

Calibrated. detenled potentiometerscn the tram
panel regulate the gain 01 the F1250. The panel
nomenclature shows the amount ol attenuation
accurately.

The ElectioVoice P1250 is the chemo tor seri-
ous. proiessional ampliitcau'on applications
which requlre optimum sound quality, speaker
protection, and the highestlevel oi construction
quality and long-term reliability

ARCHITECTS' AND ENGINEERS'
SPECIFICATIONS

The power amplifier shall be a dual-channel
model oi solidAstate design employing high-
power output devices in a lmecomplemenlary-
symmetry oumut circuit It shall be capable 01
operating irom a 120/200/220/240-V, SO/SD-Hz
ac line. The power amplifier shall contain a
modern limiter circuit with switchable time con-
stants to protect the load from damage by
amplifier clipping.

The amplifier shall contain sensing circuitry to
provide protection for the output lransnstors
against ovenemperature. excessive output
voltage. radio-irequency interterence. shorted
loads and excessive phase shill. The load shall
be similarly protected against infrasonic sig-
nals. start-upr'shuldown transients. low ac line
voltage and dc.

The power amplifier shall contain processtng
circuitry that will amelionze the phase and
transient response problems of the loudspeaker.
The built-in processor shall be capable at being
adjusted lor the enclosure type and low-
irequency characteristics at the connected
speaker.

Rear-mounted panel controls shall include an
input routing switch for selecting duaVstereo or
parallel mono operation. a switch loradiusting or
turning oil the inirasonic and ultrasonic filters.
and a switch ior selecting last or slow speed tor
the bu'lt-ln limiters. The processor controls shall
include a switch ior turning the processor oil and
selecting the enclosure type (12- or24«dB align-
ment) and titres selectable irequencies for Bi
(24 dB) alignment oi 60 Hz. 43 Hz and 26 Hz.

Front-panel indicators shall include power on.
input present. output. limit, protect and proces-
sor on LEDs for each channel. Front-panel
controls shall include a power switch and level
controls that shall be calibrated. detenled po~
tentiometers and have accurate markings. The
amplifier shall have a constantgain option that.
with Input level controls lull clockwise. provides
a 26oB voltage galn that is Identical to that oi
all EIectro-Vorce Predsion Seriesm poweram-
plifiers.

The power amplifier shall meet the iotlowrng
periorrnance specifications: maximum input
voltage. 7.75 V nns; rated output power from
20-20000 Hz at less than 0 1% THD. each
channel. >350 watts into 8 ohms. >500 watts
into 4 ohms. >600 watts into 2 ohms. >1.000
watts bridged into 5 ohms and >1.300 watts