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.
Please check product page for pricing on the different power versions on these amps.
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
LP70S and LP140M - 3 x 6922, 4 x 6550
LP275M - 3 x 6922, 8 x 6550
LP70S and LP140M - 16D x 19W x 6.38H inches
LP275M – 18.75D x 19W x 7.13H inches
LP70S – 50 Lbs.
LP140M – 53 Lbs.
LP275M – 88 Lbs
All conrad-johnson products are carefully hand assembled and each is thoroughly tested to assure conformity to our exacting performance standards. C-j's confidence in these components is reflected in their three year limited warranty covering labor and parts. Service is a top priority at conrad-johnson. In the event that a product does require service, it will be handled promptly and efficiently.