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





Denon PMA-630 amplifier

The Denon PMA-630 is a stereo integrated amplifier FTC rated for 8 ohms at 80 watts RMS per channel, 20 to 20,000 Hz  at less than 0,01% T.H.Dbetter than thouch a dual range (20 Hz and 40 Hz) subsonic filter and loudness compensation are provided, there are no conventional tone controls. Tone equalization, if desired can be provided through an optional accessory equal izer, such as a graphic-type equalizer, for which "break in" preamplifier-poweramplifier connections are provided on the rear. A shorting bar normally connects the preamp and amplifier. To use an accessory equalizer, the shorting bars are simply pulled out, thereby "breaking" the signal path for the equalizer. Other features include automatic dubbing from and to either of two recorders, a recorder output disconnect (labled Rec out) which is supposed to avoid some effect of the recorders on sound quality (thogh we could not measure non hear  any deleterious effect of the recorders on the speaker sound), and an output hold-off that prevents power supply turn-on transient from being fed to the speakers. The unit is in a metal cabinet. Three AC convenience outlets are provided.
Features:
Pre-amplifier equipped power amplifier that leads the cartridge output to the speaker by way of a simple signal route
Pure complementary circuits
Low distortion high stability DC power amplifier
High output, High gain equalizer amplifier
Power section that employs a powerful power transformer and large capacity condensers
Reduction of output impedance through the adoption of the relay driving system (damping factor: 80 upward)
Rec-out "Off" function

Specifications:
Main Amplifier Section
Type:  pure complementary push-pull system DC circuit
Rated Output (both channels driven)
From 20 Hz to 20 kHz :  80 W + 80 W RMS at each channel (T.H.D., 0,008% at 8 Ω)
At 1 kHz :  80 W + 80 W RMS at each channel (T.H.D., 0,01% AT 4 Ω)
Total Harmonic Distortion:  LES THAN 0,01%
Intermodulation Distortion:  less than 0,005% (at equivalent rated output)
Less than 0,005% (at 1 watt output)
Power bandwidth:  5 Hz to 100 kHz (IHF, T.H.D. 0,05%)
Transmission Characteristic:  DC to 100 kHz +0 -1 dB (at 1 watt output)
Input Sensitivity/Impedance:  320 mV (RMS)/100 k Ω
Output Impedance:  less than 0,09 Ω
Output Terminals Speaker:
A & B, 4 to 16 Ω load
A + B, 8 to 16 Ω load
Pre-amplifier Section
Max. Output:  25 V (at 50 k Ω , T.H.D. 0,01%)
Rated Output:  320 mV
Total Harmonic Distortion:  0,003% (at 10 V output)
Input Sensitivity/Impedance: 
Disc 1 and 2 :  2,5 mV/ 50 k Ω
Tuner ;  320 mV/ 30 k Ω
Aux, Tape :  320 mV/ 30 k Ω
Maximum Allowable Input
Disc 1 and 2 :  200 mV 1 kHz
RIAA Deviation:  less than ±0,2 dB (20 Hz - 20 kHz)
Signal-to-Noise ratio (IHF, A network)
Disc 1 and 2 ;  better than 86 dB (input terminal shorted)
Tuner, Tape, Aux :  better than 112 dB (input terminal shorted)
Filter Characteristic:
Subsonic :  20 Hz (6 dB/oct); 40 Hz (6 dB/oct)
Loudness Control Characteristic
Low Range:  100 Hz +9 dB
High Range:  10 kHz +5 dB
Power Source:  AC 120 V at 60 Hz or AC 220 V at 50 Hz
Power Consumption: 215 W ( at Ac 120 V) or 445 W (at AC 220 V)
AC outlet (USA and Canada)
Unswitched :  250 W max total
Switched ;  100 W max
Dimensions (W x H x D):  434 x 145 x 390 mm (17-5/64" x 5-45/64" x 15-23/64")
Weight:  16 kg (35,3 lbs)

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