WA-P2 "Master-Control" Hi-Fi Preamplifier
Features
In planning the purchase of a really fine hi-fi system or improving a present one, the WA-P2 should receive your serious consideration. It has many fine features that will eventually be desired. Designed to operate with the Heathkit models W-3AM, W-4AM, W-5M and W-6M amplifiers, this control-center provides almost infinite combinations of equalization, and compensation, with separate bass and treble tone control cut and boost action. It features five switch-selected inputs, three high-level inputs for 0.1 volts or higher at 0.5 megohm input impedance and two low-level inputs, for 0.1 volts or lower for magnetic phono pickup or microphone. Each input has its own level control to eliminate blasting or fading while switching through the various inputs, and will accommodate a record changer or player, tape recorder, AM-FM tuner, TV receiver, or microphone, etc. Provision is also made for a tape recorder output that is not affected by the volume or tone controls so that the program material being recorded can be monitored without affecting the recording. A special hum control is provided for absolute minimum hum level. The low impedance cathode-follower output circuit allows complete installation flexibility, making the WA-P2 ideally suited for "remote" installations as output lead length is not critical.
The frequency response of this preamplifier is within ±1½ db from 15 to 35,000 CPS. Equalization is provided for records through separate turnover and rolloff switches for LP, RIAA, AES and early 78;s. The turnover switch produces the rising low-frequency characteristics required for proper equalization since record manufacturers deliberately limit the low frequency intensity to avoid cutting into adjacent grooves. The rolloff control deemphasizes the high frequencies, removing much of the noise and scratch through four positions of 8, 12, 16 and 1 flat position. Separate tone controls provide 18 db boost and 12 db cut at 50 CPS on bass and 15 db boost and 20 db cut at 15,000 CPS on treble. Power requirements for the WA-P2 are 6.3 volts AC at 1 ampere, and 300 volts DC at 10 ma from the basic amplifier with which it is used. Additional features include tube shielding, plastic sealed capacitors, smooth acting controls, good filtering, excellent decoupling, low hum and noise level, and an all-steel cabinet.
The WA-P2 has been carefully pre-engineered for you to insure specified high performance level. All components were especially selected for their high quality, and all values are clearly stamped to avoid mistakes. The construction manual contains complete step-by-step directions, with large pictorial diagrams that can be hung over the work area for easy reference. Successful construction is assured even for the beginner.
Specifications—Inputs... Three high-level and two low-level inputs; individual level controls for each. High-level inputs, 1, 2 and TUNER, for 0.1 volts or higher; 0.5 megohm input impedance. Low-level inputs, PHONO and MIC, for 0.1 volts or lower; phono impedance normally 22 K ohm for magnetic phono pickup microphone input impedance 2.2 megohms. Frequency Response... 1.0 db from 25 cps to 30,000 cps. 1.5 db from 15 cps to 35,000 cps. Hum and Noise... 0.5 volt at TUNER input; 72 db bellow 2.0 volts RMS. 6 mv at PHONO input; 62 db below 2.5 volts RMS. 15 mv at MIC input; 70 db bellow 2.5 volts RMS. Tone Control... Separate bass and treble tone controls. Bass control provides approximately 18 db boost and 12 db cut at 50 cps. Treble control provides approximately 15 db boos and 20 db cut at 15,000 cps. Power Supply... Requires power from external source, as follows: 6.4 v AC at 1.0 amp. –300 v DC at 10 ma. Dimensions... Cabinet only: 12-9/16" long, 3-3/8" high, 4-7/8" deep. Overall: 12-9/16" long, 3-5/8" high, 5-7/8" deep. Weight... Net weight: 3-½ pounds. Shipping weight: 7 pounds.
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