Harman Kardon A12 Owners Manual - Page 5

adjustments for the limitations of the recording technique, record manufacturers have found it necessary to modify the actual frequency response of the music while it is being recorded. Thus, to avoid overcutting and consequent distortion, a measured and deliberate reduction is effected in low frequency response by selecting a "turnover frequency" and by recording attenuated response below that point. To assure optimum signalto-noise at the high frequency end when the record is played at home, the highs are deliberately exaggerated during the recording process. A measured and deliberate boost is effected above a certain frequency. This combination of deliberate exaggeration at the low and high ends of the frequency response can be expressed in a "recording curve." When the record is played a mirror image of that curve should be available so that the idea! "flat" response may be achieved. Since several different recording curves have been used in the past (differing with respect to the turnover points and the degree of emphasis or de-emphasis) a choice of playback curves is provided in Harman-Kardon instruments. The three record equalization positions compensate for the characteristics of over 30 recording labels. LP: Most American long-playing records made before 1954 and some European LP's. Labels include: Columbia, London, Mercury, Oceanic, Remington, Tempo, Urania, Vanguard-Bach Guild, Vox, Westminster, RCA Victor (older), Atlantic, Decca, Polyphonic, Cetra-Soria, Esoteric, Haydn Society, MGM, Angel. RIAA: Most American records made after 1954, all records cut to standards of Audio Engineering Society. NAB, new RCA Victor Ortho, and newly standardized RIAA. Labels include RCA Victor (newer), Extended Play 45, Blue Note Jazz, Canyon, Capitol, Good Time Jazz, Mercury, some London, Bartok, Caedmon, CapitolCetra, Philharmonic, EMS. EUR: Most European Long-playing, some American I.P's and most 78 RPM discs. The above listed positions are the recommended settings for almost all recordings made, however, it should be noted that it is not compulsory to adhere strictly to the recommendation. For example: Capitol records are recommended to be played on the "RIAA" equalization curve, but if for some reason (room acoustics, speaker location, type of program source) the sound is not quite satisfactory, it is permissible to change the equalization control setting to "EUR" or "LP." If the overall sound quality pleases you more, leave it that way. You hearing should be the final judge as to the exact equalization control setting. Tape Head: If you are using a tape deck without its own preamplifier in conjunction with this amplifier, connect the tape recorder head to the jack on the rear panel marked "Tape." This will allow the A-12 to act as the preamplifier for the tape recorder and will automatically compensate for the NARTB 7-1/2 IPS playback curve when the Function Selector Switch is placed in the "Tape Head" position. This was thoroughly covered in the paragraph entitled "Tape Input" Bass and Treble Controls: Separate Bass and Treble controls are incorporated to provide the full range of tone adjustment required for maximum high fidelity performance. These controls can either boost or cut the Bass and Treble tones of this instrument. The controls should be set in accordance with your hearing preference speaker characteristics and room acoustics. Loudness Control: This control is used to adjust the volume level of any program material. Its effect is selectively varied by the Contour Control. Dynamic Contour Control: One of the limitations of human hearing is its tendency to lose sensitivity to the very low and very high pitched sounds, as the sound level is reduced, It is this characteristic (known as the Fletcher-Munson effect) which causes one to play music programs at high level in order to experience the fullness of tone available from fine modern recordings and identified with "live" listening. The Harman-Kardon Dynamic Loudness Contour Control compensates for the FletcherMunson effect, eliminating high reproduction level as a requisite for full enjoyment of reproduced music. Four positions of compensation are provided to allow the selection of the one most suited to your hearing. Each position (0-3) causes the Loudness (Volume) control to perform with a different degree of compensation, the amount increasing with each clockwise setting. Position 0 is uncompensated. Position 1 provides somewhat less compensation than that required to match the Fletcher-Munson curves. Position 2 matches the FletcherMunson curves. Position 3 provides a greater amount of compensation than the curves suggest. Since hearing characteristics vary from person to person (some require more and others less compensation) the great flexibility provided in these controls can be appreciated. In operation, the proper choice of contour is easily made, by switching through the several loudness contour positions and selecting the one which sounds best to you. Speaker Selector Switch: Operation of this switch was previously discussed in Speaker Connections section. ADJUSTMENT CONTROLS Hum Bucking Control: The Hum Bucking Control is accessible at the rear of the chassis. Adjust this control for minimum hum after setting controls for Phono (RIAA) operation and the volume level slightly above normal. In some installations where a record player, tape recorder, or other auxiliary AC operated equipment is used, hum may be encountered due to voltage differences between the various units. This may be eliminated by reversing one or all of the AC power plugs. Simply reverse one at a time until improvement is experienced. 4