INSTRUCTION MANUAL for the JC-2 PREAMPLIFIER
IMPORTANT Please read these instructions carefully and completely before operating the JC-2 preamplifier. A great deal of effort went into the design and construction of this precision device. Understanding its functions will enable you to use it to fullest advantage.
INSTRUCTION MANUAL for the JC-2 PREAMPLIFIER 1. INTRODUCTION The MARK LEVINSON JC-2 PREAMPLIFIER is the distillation of years of scientific research and careful listening. The amplification circuitry designed by John Curl combines the advantages of class A, completely complementary push-pull operation, high open-loop bandwidth, and low feedback configurations in order to approach perfect solid-state preamplification of the most demanding recorded musical material.
3.2. Power Supply Connection The power supply for the JC-2 is mounted in a separate chassis to eliminate hum pick-up. Check the voltage the power supply comes a cable with a three power supply label to be sure they correspond to the voltage of the power source being used. From one end of the power supply comes a cable with a three prong AC plug on the end of it. Connect this end to a wall outlet, using a ground adapter plug if your wall outlet will not accept three prongs.
TAPE 1/TAPE 2 - selects either tape input 1 or tape input 2 for the input/ monitor switch. MONO/STEREO - selects either a mono or a stereo mode at the main outputs. HIGH/LOW - selects either 21dB gain (HIGH) or 11dB gain (LOW) in the output stage. Line level inputs should generally be used only with the low gain setting. Low level phono inputs can be used with either HIGH or LOW depending on the output level of the phono cartridge.
UNIVERSAL PHONO PLUG-IN CARDS System: Gain: Overload: 1kHz 20kHz A Two UP-1A cards are normally supplied with the JC-2 unless otherwise specified. This system accepts Input impedance: 47kOhms. 36dB 100mv 900mv B The UP-1B system offers lower sensitivity but increased headroom for the highest output magnetic phono cartridges. 30dB 220mv 1.6v C This set provides exact equalization for the Brüel & Kjaer series of cartridge measurement records. Information on request.
6. SPECIFICATIONS Phono Section: Gain* OVERLOAD POINT* 1kHz 1kHz 36dB 100mv min. MAXIMUM OUTPUT CHANNEL TRACKING FREQUENCY RESPONSE 18Hz to 20kHZ 18Hz to 20kHz -1.5dB down at 6v min. .5dB ( .2 typ.) 18Hz, 30kHz min. NOISE below 10mv, inputs shorted below 10mv, 600ohms load 18Hz to 20kHz: 85dB 83dB ASA "A" weighted 90dB min. 88dB *(see also Section 5) INPUT IMPEDANCE RECOMMENDED LOAD OPEN LOOP BANDWIDTH SLEW RATE NOISE (JC-1SM) 47kOhms* 10kOhms or higher 1500Hz min.
7. WARRANTY All MARK LEVINSON products are guaranteed for five full years from date of purchase. Parts and labor will be furnished free of charge. The manufacture assumes no responsibility for damaged or abused equipment and reserves the right to determine cause of defects. IMPORTANT: Addendum to Section 4 An output coupling selector switch is located between the line amplifiers on the main circuit board.
NEW DEVELOPMENTS IN THE JC-2 JC-2 Preamplifiers starting with serial number 2148 differ from previous units. They are equipped with lemo connectors, a new power supply (PLS-150), two phono inputs and new phono plug-in cards. PHONO SECTION The standard systems are now A3, D5 and d6. The plug-in cards contain a two-station program switch for selection of input and gain characteristics.
TONEARM CABLE ADAPTOR From an effort to simplify the connection of existing turntables to MLAS Preamplifiers fitted with Lemo connectors, we have developed the CA-1 cable adaptor. The CA-1 is a solid block of aluminum 2X2X .75" machined to exact tolerances and finished in our standard brushed black anodized surface. It replaces the phono connectors of any existing tonearm cable and allows connections to our preamps with an LL (Lemo to Lemo) cable set. (see page 11 of our 12-1-76 notice.
INSTRUCTIONS FOR ASSEMBLING THE CA-1 CABLE ADAPTOR 1. The CA-1 may be mounted to a shelf, cabinet, or turntable base with one wood screw. This keeps fragile tonearm leads from breaking or flexing. 2. Use LL-.6 or LL-3 cables to connect with your JC-2 or LNP-2 preamplifier. 3. Cut the phono connectors from the tonearm leads, nothing which wire is left and which is right. 4. Strip the ends about 1/2" so that a center conductor and shield are prepared for each end. 5.
PLS-150 POWER SUPPLY SYSTEM JC-2 preamplifiers with Lemo connectors are equipped with the PLS-150 Power Supply. The PLS-150 Power Supply is considerably larger and heavier than the ones delivered with previous units. We recommend that it be positioned with the cable end facing the wall and the front plate facing forwards. In this way, the two LED' s will be visible. these lights indicate that the power supply is receiving the correct AC voltage and is delivering the correct DC voltage.
