Why it mattered
- 01
It proved that valve amplification and horns could address crowds far beyond the unaided voice, building on repeater tubes.
- 02
Its success fed Western Electric's move into theatre sound, including the 555 driver.
Pictured in this passage
Engineering record
- Documented use
- Calvin Coolidge's outdoor address at Harvard, 1925[1]
Original pricing
No reliable period price located
2026 equivalent
Not calculated without a reliable original price.
Public price evidence was not sufficient to publish a defensible original figure.
Use in the field
Calvin Coolidge at Harvard University, 1925[1]
Manuals & original documents
No authoritative manual or original document has been located for this profile.
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Know more about 1-A public-address system?
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