Bang Olufsen Beomaster 4400 Owners Manual

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1977 «15-25

BANG &OLUFSEN A/S
LABORATORY INFORMATION
DESIGN PRINCIPLES
BEOMASTER 4400.

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CONTENTS Page

THE DESIGNER'S DILEMMA ....................................... S
Balancing a number of choices ......................................... 3
Techniques ~ or performance ...................................... . . V 4
Do you really want a concert hall in your living room? ........................ 5
Defining the problem ................................................. 6
THE GRAMOPI-iONE PREAMPLIFIER ................................... 6
Dynamic range and noise ............................................... 6
Thermal noise ....................................................... 7
Phone Overload voltage ................................................ 7
High Pass Filter ..................................................... 8
Equalisation ........................................................ 8
TAPE RECORDER INPUTS AND OUTPUTS .............................. 9
Tape 1 Facility ...................................................... 9
Tape 2 Facility ...................................................... 9
TONE CONTROLS ................................................... 10
The Volume Control ................................................. 10
Balance Control ...................................................... 10
Bass and Treble Controls ............................................... 10
High and Low Filters .................................................. 11
Mono Switch ........................................................ 11
Loudness Control .................................................... 12
Linear Switch ..................................................... 12
Loudspeaker Switching ................................................ 12
THE FM TUNER ................................................... 12
The Front End ...................................................... 13
The IF Section ...................................................... 13
Stereo Decoder ...................................................... 14
The Muting Circuit ................................................... 17
THE POWER AMPLIFIER ............................................. 17
The Importance of Specifications ........................................ 17
Load Handling Capability ............................................. 1'7
Transient Intermodulation Distortion ..................................... 19
What is TID? ........................................................ 19
Elimination of TID .................................................. 20
Crossover Distortion .................................................. 21
Power Output ....................................................... 22
The Overload Indicator ................................................ 25
Protection Circuits ................................................... 28
THE ADVANTAGES OF INTEGRATION ................................. 29
TECHNICAL DATA .................................................. 30
Block Diagram of the Beomaster 4400 .................................... 31
THE DESIGN TEAM ................................................. 32

APPENDIX I - "Causes and Elimination of TID. Paper to the 53rd Convention of the
AES - 1975.

APPENDIX II ~ Specifying the Loudspeaker-Amplifier Interface", Paper to the 53rd
Convention of the AES »- 1975.

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26

Fig. 28a Fig. 281)

as

\ u n. rum:
in n

Spectrum analysis, same as above
at 7 3 [13 rated power.

Fig. 290 Hg. 29b

. .m

um an mm mm new

Spectrum analysis of intermadu-
lation distortion at rated power,
signal frequencies 250.8000 Hz,
amplitude ratio 4 :l .

1er um um um ma 0) mm

even for a signal as short as one half of a sine wave. The light will then stay on long
enough to be clearly visible. No damage will occur if the lamp lights, or even stays lit. It
only indicates that the output stage is clipping, and therefore producing a higher than
specified level of distortion.

The indicator is not a static device indicating a fixed power or voltage level. It operates