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





Heathkit AA-1800 power amplifier

New Higher-Power pro-Series Amplifier - the most powerful Heathkit amp ever.
Heath Company helped pioneer the field of high-power amplifeiers. Now, advances in high-power output devices, new design technology and extensive listening tests make the Heathkit AA-1800  Pro-Series Audio Amplifier one of the best high-power amps available. The wider dynamic range achieved by new recording techniques require power and headroom to reproduce the full sound spectrum, without clipping peaks. People who listen to the AA-1800 find accurate, clearly defined music - at a wallet-pleasing price.
From the power cords to the speaker outputs, more value is built into the AA-1800. a wire-frame chassis, similar to those used in computers, makes the AA-1800 a more durable unit in a smaller package, with excellent ventilation. This new chassis simplifies the easy 24-hour kitbuilding experience, too. Two line cords with remote AC switching relieve your preamp from the need to switch high currents. Convection cooling means no fans and quieter operation. Individually fused power supply lines, along with rugged output devices, eliminate electronic dissipation limiters - which can cause tweeter-damaging clicks and pops. LEDs for each channel indicate full easy access.
Complete speaker  protection includes a speaker turn-on delay - which keeps power-up and power-down transients away from the speakers. In fact, the AA-1800's speaker protection system is so efective, we've applied for a patent.
Thermal circuit breakers protect the system from excessive heat.
Designed in the striking pro-Series style, the AA-1800 can be mounted in any EIA Standard 19-inch rack, such as the AE-1705 Pro-Series Rack. Large side handles are provided for easy rack mount installation.

Specifications
Frequency Response:  20 Hz - 20 kHz ±0,1 dB;  3 Hz - 100 kHz ±1 dB (at 1 watt)
Total Harmonic Distortion Plus Noise:  0,025% (from 250 mW to 250 Watts)
TIM (DIM 100):  less than 0,03% (3,18 kHz square wave and 15 kHz sine wave mixed 4 to 1, f[c]=100 kHz, measured at rated output.
Hum and Noise (unweighted):  -85 dB (1 watt ref.)
Full Power Trip  Frequencies of Speaker Protection Circuit:  less than 16 Hz, more than 30 kHz.
Low Frequency Damping Factor:  greater than 100
Input Sensitivity:  110 mV ( for 1 W at 8 Ω)
Input Impedance:  20 k Ω, shunted by less 50 pF
Channel Separation:  60 dB min. 20 Hz to 20 kHz
Power Requirements:  120 V AC, 60 Hz
Power Consumption:  1200 Watts
Dimensions (W x H x D):   472,6 x 177,5 x 415,5 mm (19" x 7" x 16,75")
Weight:  22,68 kg ( 50 lbs)

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