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Conrad-Johnson LP275M
SOLD $30,000.00
SEP
2010
Manufacturer's Website
These new conrad-johnson linearized-pentode
amplifiers are designed to meet the needs of industry professionals and
audiophiles who seek audio perfection for their reference systems. While
the demand for precision and musicality is the common denominator of
these systems, the power requirements can vary considerably. To meet
these varying needs, we offer the LP70S stereo amplifier rated at 70
watts per channel, the LP140M monaural amplifiers rated at 140 watts and
the LP275M monaural amplifiers rated at 275 watts.
The LP amplifiers share the same basic audio circuit. This circuit
consists of three stages. The input signal is amplified by a triode
amplifier. The signal is then direct coupled to a cathode coupled
phase-inverter. This high current, triode phase-inverter stage provides
a balanced, low impedance drive to the output stage. Output power is
developed by 6550 output tubes, chosen for their musical accuracy, high
power, and reliability. Each channel of the LP70S uses one pair of 6550s
to produce 70 watts per channel, the LP140M uses two pair to produce 140
watts per each mono chassis, and the LP275M uses four pair to produce
275 watts. The output tubes are operated in ultralinear configuration
which offers an optimal combination of high power and low distortion.
The massive conrad-johnson transpectral output transformers have
intricately interleaved wind-ings designed for extended bandpass and
high phase linearity. A small amount (about 12 dB) of loop negative
feedback reduces distortion and achieves a sufficiently high damping
factor to control reactive loudspeaker systems.
Separate, low impedance, discrete dc power supply regulators are
provided for the input and phase-inverter stages, preventing the output
stage from modulating these stages through the power supply. These power
supplies are designed to maintain a rock solid supply at all audio
frequencies. The main power supply reservoir uses a bank of massive
custom polypropylene capacitors. No electrolytic capacitors are used in
any of these power supplies.
These amplifiers require no complicated adjustments or specialized
equipment to maintain. To assure continued peak performance, the owner
need only make a simple bias adjustment when new tubes are installed.
Built in LED bias indicators allow the user to make this adjustment
using only the supplied screwdriver.
At conrad-johnson we are fully aware that component parts contribute
importantly to the sonic performance of any circuit design. The LP
amplifiers maintain the exacting quality standards for which con-rad-johnson
is internationally known. Resistors are precision laser-trimmed metal
foil types. Coupling capacitors are the new Teflon CJD caps and all
other audio-circuit capacitors are polystyrene, while the power supplies
use large value polypropylene in parallel with polystyrene capacitors.
There are no electrolytic capacitors in the audio circuits or in the
related power supplies. Proprietary wide-bandwidth output transformers
contribute to excellent high frequency performance. Even the machined
gold plated OFC connectors and the internal wiring have been carefully
selected for optimal sonic performance. Attention to details of this
kind enable us to extract the full potential from our circuit designs
and ensure that our products will perform to this potential for years to
come. Visit a conrad-johnson dealer soon to hear for yourself just how
true to the music an amplifier can be.
Specifications:
Power:
LP70S - 70 watts per channel from 30 Hz to 15 KHz at no more than 1.5 %
THD or IMD, both channels driven into 4 ohms (also available connected
for 8 or 16 ohm loads)
LP140M - 140 watts from 30 Hz to 15 KHz at no more than 1.5 % THD or IMD
into 4 ohms (also available connected for 8 or 16 ohm loads)
LP275M – 275 watts from 30 Hz to 15 KHz at no more than 1.5 % THD or IMD
into 4 ohms (also available connected for 8 or 16 ohm loads)
Sensitivity: .5 V to rated power
Frequency Response (at 10 watts): 20 Hz to 20 kHz, +/- .25 dB
Hum and Noise: 102 dB below rated power
Input Impedance: 100 kOhms
Tube Complement:
LP70S and LP140M - 3 x 6922, 4 x 6550
LP275M - 3 x 6922, 8 x 6550
Dimensions:
LP70S and LP140M - 16D x 19W x 6.38H inches
LP275M – 18.75D x 19W x 7.13H inches
Weight:
LP70S – 50 Lbs.
LP140M – 53 Lbs.
LP275M – 88 Lbs.
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