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

Dual C 819

 We shall be pleased to send you the complete Hirsch-Houck report if you write to us  directly. If you'd rather not wait, here are some additional key excerpts:
" in its price class, the Dual 819 has some formidable competitors, and one has the right to expect first-class performance from any cassette deck selling for more than $400. nevertheless, even in such distinguished company, the 819 stands out."
"… the extremely low flutter, flat frequency response and low noise level of the 819 , combined with its superbly accurate and useful meters, make this one of the more attractive values ina high-quality cassette deck. Such features as the fade/edit system and the bidirectional memory can be considered simply as bonuses."
"The Maxell UD-XL-I tape provided a very flat record-playback response (at -20 dB) within ±0,75 dB from 30 to 15,000 Hz …. The response with Sony Ferrichrome was flat within ±1 dB from 33 to 15,000 Hz … the Dolby tracking was among the best we have measured … with a weighted RMS reading the flutter was an amazing 0,035%. It is clear that in all aspects of its design and performance, the Dual 819 is a first-class unit."

One final comment of our own. As you know, Dual's reputation for quality, precision and reliability has been based upon the performance of our turntables. When we introduced our first cassette decks, we knew they must establish a reputation of their own. And it is evident that they are doing just that.
The precision DC motor is fitted with an integrated frequency generator and modern control IC for speed regulation. The Dual decoupling motor suspension provides propagation of vibration and running noises.  A precision made flat belt drives the capstan and thereby plays its parts in the overall excellence of the wow and flutter characteristics. The tape take-up torque receiver its drive via a second belt direct from the motor so that disturbances such as differences in cassette winding have no effect on the tape transport.
For the fast wind facility a functionally reliable gear drive is used. This guarantees trouble-free winding even for older cassettes.
A photo-transistor continuosly monitors tape movement and prevents formation of loops in the tape. At the same time it also provides the signals for auto stop. This function is independent of the cassette or tape switching foil.
Careful tape location and precise azimuth setting ensure optimum treble reproduction and prevent level fluctuation.
The amplifier is functionally designed and constructed with plug-in modules for easy accessibility. In spite of the complexity of the equipment all the components are readily accessible.  The expense occured in achieving this, in comparasion with other models in this price category, will be of no interest to the service technican but you will find it satisfying to know that if a repair should ever be necessary every thought has been given to this being effected quickly and at minimum cost.
Tape Speed:  4,75 cm/s
Deviation from Correct Speed:  less than ±1%
Fast Winding Time:  below than 65 sec for C-60 cassette
Frequency Response:
Fe Tape :  20 - 15,000 Hz
CrO₂ Tape :  20 - 16,000 Hz
FeCr Tape :  20 - 16,000 Hz
Signal-to-Noise Ratio [with Dolby/without Dolby] (weighted):
Fe Tape :  better than 64 dB /  57 dB
CrO₂ Tape :  better than 64 dB /  57 dB
FeCr Tape :  better than 67 dB /  61 dB
Wow and Flutter: 
RMS weighted :  less than ±0,07%
To DIN for Reproduction Only :  less than ±0,10%
To DIN for Recording/Reproduction :  less than ±0,14%
Harmonic Distortion:
Fe Tape :  less than 1,0%
CrO₂ Tape :  less than 2,8%
FeCr Tape :  less than 1,5%
Channel Separation at 1 kHz:
Between Stereo Channels :  better than 40 dB
In Opposite Direction :  better than 70 dB
Erasure:  better than 70 dB (1 kHz)
Oscillator (Push/Pull oscillator):  100 kHz
Input Sensitivity/Impedance:
Microphone :  0,26 mV/2 k Ω
DIN connector :  0,50 mV/6,3 k Ω
RCA jacks :  40 mV/580 k Ω
Overload Capacity of Inputs:
DIN Connector :  40 dB
Mic Connector :  50 dB
Output Level/impedance (adjustable):
DIN connector :  0 -580 mV/ 5,5 k Ω
RCA jacks :  0 - 580 mV/2,0 k Ω
Tape Monitor (Photo-electric shut-off time):  less than 0,6 sec
Headphone Impedance:  4 - 2000 Ω
Semiconductors:  6 ICs;  39 transistor; 27 Diodes, 2 LEDs
Power requirement:  110 - 125 V, 220 - 240 V; 50/60 Hz
Power Consumption:  16 watts
Dimensions (W x H x D):  438 x 148 x 360 mm

Weight:  6,5 kg

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