. Bell telephone magazine . irSlSJ^Ct 1—in 1—in 1—1 -- ;:l -« »«.-., »«. TMB>aKa>rP>a j^ oaoutfw S>«>^(-<r^< Figure 3. Slmplitied Schematic of a Single Chaxxel for the Phtl-adelphia-Washixgtox Figure 4. Toll Equipment at W ashixgtox. PERFECT TRANSMISSION AND REPRODUCTION OF MUSIC ing to a power amplification of 100,000 times, the overallcharacteristic of the lines—from the Academy of Music toConstitution Hall—was flat to within + 1 db over the entirefrequency range from 40 to 15,000 cycles. Due to the em-ployment of very stable amplifiers and
. Bell telephone magazine . irSlSJ^Ct 1—in 1—in 1—1 -- ;:l -« »«.-., »«. TMB>aKa>rP>a j^ oaoutfw S>«>^(-<r^< Figure 3. Slmplitied Schematic of a Single Chaxxel for the Phtl-adelphia-Washixgtox Figure 4. Toll Equipment at W ashixgtox. PERFECT TRANSMISSION AND REPRODUCTION OF MUSIC ing to a power amplification of 100,000 times, the overallcharacteristic of the lines—from the Academy of Music toConstitution Hall—was flat to within + 1 db over the entirefrequency range from 40 to 15,000 cycles. Due to the em-ployment of very stable amplifiers and underground cableswhich were not subject to rapid changes in temperature, thetransmission variation over the entire frequency band did notvary more than a few tenths of a db from day to day. Amplifiers and equalizers are required for the short audio-frequency circuits at each end, as well as for the carrier cir-cuits. Existing apparatus was employed, although modifiedslightly to meet the unusual conditions of the Philadelphia-Washington demonstration. At Philadelphia both amplifierand equalizer for the audio-section were located in the Phila-delphia toll office, but in Washington, the amplifier was at thetoll office, and
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Keywords: ., bookauthoramerican, bookcentury1900, bookdecade1920, bookyear1922
