GR2910B
(en )
1930-09-10
SOUND PLAX (PHONOGRAPH DISC) AND METHOD MADE IT.
AT112399B
(en )
1929-02-25
Sound recording and reproducing apparatus.
FR725084A
(en )
1932-05-07
Phonograph record
FR705593A
(en )
1931-06-10
Phonograph record
FR647892A
(en )
1928-12-03
Electro-magnetic sound reproducer
FR633921A
(en )
1928-02-06
Improvements in sound transmission and reproduction
AT134391B
(en )
1933-07-25
Sound recorder and player.
DK47661C
(en )
1933-08-21
Sound reproducing apparatus.
AT116777B
(en )
1930-03-10
Teaching and music apparatus.
GR1204B
(en )
1926-06-12
PHONOGRAPH DISC AND HOW TO MAKE THEM.
ES124109A1
(en )
1932-01-01
Improvements in the methods and devices for recording sounds and sound records.
FR677003A
(en )
1930-03-03
Electro-magnetic phonograph reproducer
GR3530B
(en )
1932-02-11
SIMPLIFICATION OF THE GRAMOPHONE AND PHYSICAL PERFORMANCE OF THIS VOICE.
DK44384C
(en )
1931-07-20
Optical Film Sound Recorder.
DK37820C
(en )
1927-08-15
Sound reproducing apparatus.
CA278080A
(en )
1928-02-28
Combination phonograph and piano
ES111250A3
(en )
1929-04-01
Improvements in sound recorders and reproducers.
DK42874C
(en )
1930-09-01
Gramophone record.
GR1869B
(en )
1928-06-11
METHOD OF MANUFACTURING DISCS OF GRAMOPHONES AND SIMILAR MATERIALS OF NEW TYPE.
ES121157A1
(en )
1931-01-16
Improvements in the reproduction of sounds.
CA280725A
(en )
1928-06-05
Sound reproducer testing method
GR2288B
(en )
1929-05-08
IMPROVEMENTS IN CLEANING OR CLEANING EQUIPMENTS OF GRAMOPHONE AND SIMILAR SOUND PLATES.
DK47662C
(en )
1933-08-21
Sound amplifier.
GR1651B
(en )
1927-10-24
WOOD HORN PHONOGRAPH.
FR715419A
(en )
1931-12-03
Linear sound inscription and its reproduction