1. Electrical Amplification in the studio and on the Radio

2. Making recordings acoustically

4. The business use of recorders 1902 Columbia gramophone markets the dictophone.

5. The moving coil loudspeaker loudspeaker invented in 1911 by Peter Jensen and Edwin Pridham President Woodrow Wilson came to San Diego September 9, 1919 to plead for the League of Nations

6. Commercial Radio Westinghouse VP Harry Davis joined Conrad Sept. 30, 1920, to create 100-watt transmitter in Pittsburgh - given call letters KDKA by Commerce Dept. Oct. 27 - transmitted election returns Nov. 2 - began regular scheduled broadcasts every evening 8:30-9:30 pm - power of transmitter increased to 500 watts 1921 - Midcontinent chain of 6 stations by 1925 KDKA's studio in East Pittsburgh, Pennsylvania, c.1923

7. Early microphones Western Electric 387 RCA 4a (mid-twenties) RCA 44A/B Velocity microphone

8. Ribbon & Condenser microphones RCA 44BX 1932 RCA 77A-DX 1932-1954 Shure 55 Unidyne

9. Electric recordings 1925 - Henry C. Harrison at Bell Labs developed a matched-impedance recorder to improved the frequency range from the previous narrow 250-2,500 cycles range of acoustic recorders to a wider range of 50- 6,000 cycles using the condenser mic, tube amp, balanced-armature speaker, and a rubber-lined acoustic recorder with a long tapered horn. Harry Grow inspecting cutter

10. Electric recordings Blumlein cutter, 1934 HARRY NYQUIST NYQUIST THEOREM (1928) the highest reproducible frequency in a digital system is equal to or less than one-half of the sampling frequency