Bang & Olufsen Beogram 4000c, Technical Sound Manual

Page 1: ...Beogram 4000c Technical Sound Guide Bang Olufsen A S This manual is for information purposes only and is not legally binding November 27 2020...

Page 2: ...ross 7 3 2 Signal Levels 8 3 3 Tip shape 10 3 4 Bonded vs Nude 12 3 5 Tracking force 12 3 6 E ective Tip Mass 12 3 7 Compliance 13 3 8 Soundsmith SMMC20CL 13 4 Audio Specifications 14 4 0 1 Magnitude...

Page 3: ...Emil Berliner was awarded a patent for a sound recording and reproducing system that was based on a groove in a rotating disc rather than Edison s cylinder the original version of the system that we k...

Page 4: ...are the same at Time 0 ms However it is also evident that when this is true they have very di erent amplitudes in fact the amplitude would have to double for every halving of frequency a drop of 1 oc...

Page 5: ...ns of the RIAA equalisation filter define the transition points as time constants instead of frequencies So instead of 50 Hz 500 Hz and 2122 Hz as shown in the response plots the points are listed as...

Page 6: ...down left up right for example This means that signals that are identical in both channels move the stylus laterally exactly as in earlier monophonic discs 4 Figure 2 10 An over simplified depic tion...

Page 7: ...eophonic Transducer Cartridge In 1963 Erik R rbaek Madsen of Bang Olufsen filed a patent for a cartridge based on the Moving Iron principle In it a cross made of Mu metal is mounted on the stylus Each...

Page 8: ...be encoded without incurring additional distortion that is inherent in the encoding system itself is when the maximum or minimum value in the audio signal reaches the highest possible signal value of...

Page 9: ...here is a relationship between the total playing time of a vinyl disc and the modulation velocity In order to have 20 minutes of music on a 12 LP spinning at 33 1 3 RPM then it the standard method was...

Page 10: ...here are a number of options when choosing the shape of the playback stylus 3 3 Tip shape The earliest styli were the needles that were used on 78 RPM gramophone players These were typically made from...

Page 11: ...k deeper into the groove making it more di cult for it to move independently on the two audio channels The second is that the point of contact between the stylus and the vinyl becomes smaller which ca...

Page 12: ...pin which is in turn connected to the cantilever the long arm that connects back to the cartridge housing This bonded design is cheaper to manufacture but it results in a high mass at the stylus tip...

Page 13: ...the compliance of the stylus suspension Compliance is the opposite of spring sti ness the more compliant a spring is the easier it is to compress and the less it pushes back Like many other stylus pa...

Page 14: ...of 70 7 mm sec 4 0 3 Rotational speed Every recording playback system whether for audio or for video signals is based on the fundamental principle that the recording and the playback happen at the sam...

Page 15: ...changes in the speed that are higher than 100 Hz This is typically only a problem with analogue tape decks caused by the magnetic tape sticking and slipping on components in its path and is not often...

Page 16: ...nal relative to the average frequency however the e ect of very slow and very fast changes have been reduced by the filter Finally the standard deviation of the variation from the average is calculate...

Page 17: ...mith SMMC20CL Stylus Nude 0 12 mm square Radius of curvature Contact Line Recommended tracking force 1 3 g Compliance 28 m mN E ective tip mass 0 32 mg General information Automatic speed selection Ye...

Page 18: ...nditions in the Cutting and Playing of Stereo Disk C R Bastiaans Vol 11 Issue 1 Jan 1963 Factors A ecting the Stylus Groove Relationship in Phonograph Playback Systems C R Bastiaans Vol 15 Issue 4 Oct...

Page 19: ...commendations for Lateral Cut Commercial and Transcription Disk Recordings 98 Processed Disk Records and Reproducing Equipment 386 Method of Measurement of Speed Fluctuations in Sound Recording and Re...