What is stereo?




There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.




H.H. Scott '59





Harman/Kardon Citation Eleven

 Harman/Kardon Citation Eleven
Professional Solid State Stereophonic Preamplifier/Audio Equalizer

When Harman/Kardon introduced the Citation  A preamplifier  several years ago, it represented  a major breakthrough in solid state design. Within a short period of time, it became the audiophile's standard of excellence. In fact, the "A" is still recognized today by many audio authorities as the finest stereo preamplifier ever designed.
With the introduction of the Citation Eleven, Harman/Kardon has once again innovated a major change in the design and function of high performance solid state stereo preamplifiers.
The Citation Eleven uses the potential of transistors more completely and creatively than any other preamplifier in existance. It is a computer-crafted instrument that easily meets or exceeds every performance parameter ever established for a preamplifier. The simple truth is that the Citation Eleven is the best stereo preamplifier ever made.
 Total Flexibility and Control Over Acoustics
An important new design concept has been incorporated into the Citation Eleven to make it the most versatile stereo preamplifier ever created for home use. H/K engineers have determined that standard tone controls, even professional switched types, limit flexibility for they do not permit precise adjustment of program material over the entire audio range.
The Citation Eleven employs a professional type audio equalizer which gives the user complete control over program material, room acoustic and deficiencies within the speakers. Operating at predetermined hinge points, the audio equalizer adds or deletes audio energy to any of five points within the audio spectrum to compensate for inaccuracies in program material or within the playback system. It is no longer required to match room acoustic to the speakers by re-positioning furniture or by adding draperies and rugs to the room. The Citation audio equalizer controls room acoustics by permitting the user to set the five controls to suit his own personal requirements. Hot spots, ear-piercing high, frequency response drop out, excessive bass and even mid-frequency harshness can now be cancelled out by adding or deleting audio energy at the specific points in the audio spectrum where these probllems occur.

Below: another version of H/K Citation Eleven
 Listening quality of the Citation Eleven is superb , and not easily described in terms of laboratory measurements. The preamplifier offers solidity combined with an openness that sets it apart from all others. The more you listen to the Eleven , the more you become aware of the great achievement it represents. Anyone who wants the very best and will not be satified with anything less than the finest, will be well-advised to see and hear the new Citation Eleven.
Specifications
Audio Output:  up to 6 volts RMS into 10 k ohms
Frequency Response:  below 5 Hz to beyond 125 kHz ±0,5 dB
Square Wave Rise Time:  less than 1 ms at 20,000 Hz
Square Wave Tilt:  less than 5% at 20 Hz
Total Harmonic Distortion:  less than 0,05% at 6 volts RMS from 10 to 30,000 Hz
Below residual level of most test instrumentation at 2 volts RMS and below
Intermodulation Distortion:  less than 0,05% at the equivalent 6 volts RMS output
Noise (Unweighted):
Low Level :  65 dB below 6 volts at 10 mV input reference
High Level:  80 dB below 6 volts  ( volume control wide open)
Residual:  900 dB below 6 volts
Sensitivity:
Low Level :  1,5 mV for 2 V output
High Level :  150 mV for 2 V output ( in all auxiliary positions except Aux 3, which is 300 mV for 2 V output)
High Cut Filter:  -8 dB at 10,000 Hz, 6 dB /octave slope
Subsonic Filter:  -12 dB at 15 Hz, 6 dB/octave slope
Input Impedance:
Phono :  47  k Ω
Aux :  20 k Ω
Output Impedance:
Source Impedance :  less than 500 Ω
Recommended Load :  10, 00 Ω or greater
Phono Overload:  Greater than 115 mV
Audio Equalizers:  Five sliding controls operaating at the following hinge points; 60, 320, 1k, 5 k, 12k Hz. Boost and cut ±12 dB, each position
Phono Equalization:  RIAA curve ±0,5 dB
A.C. Convenience Receptacles:  Three switched. One unswitched
On/Off Switch:  Pushbutton, heavy duty rating
Function Selector:  Mag. Phono 1, Mag. Phono 2, four high level positions
Mode Selector:  Stereo, Stereo Reverse, Mono, LeftChannel only, Right Channel only
Balance Control:  Zero to infinity type
Volume Control:  Close tracking dual potentiometers, frequency insenstive within range of frequency response specifications
Speaker Selector:  Permits choice of speaker system 1, system 2 or both at once when preamplifier is connected in the manner described in the instruction manual
Headphone Receptacles:  Two low impedance headphone receptacles controlled by front panel speaker selector switch. May be switched in or out at user's discretion.
Output Receptacles:  Four main preamplifier outputs. Four outputs for tape recording
Inputs:
Two pair for low level phonograph
Four pair for high level equipment
Two pair for tape monitor
Two grounding termnals
Power Requirements:  117 volt, 50/60 Hz or 220 volt operation, AC line fuse
Dimensions (WxHxD):  16-1/16" x 4-3/4" x 12"
Weight:  20 pounds

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