Early recordings were made entirely acoustically, the sound being collected by a horn and piped to a diaphragm, which vibrated the cutting stylus. Sensitivity and frequency range were poor, and frequency response was very irregular, giving acoustic recordings an instantly recognizable tonal quality. A singer practically had to put his or her face in the recording horn. Lower-pitched orchestral instruments such as cellos and double basses were often doubled (or replaced) by louder wind instruments, such as tubas. Standard violins in orchestral ensembles were commonly replaced by Stroh violins, which became popular with recording studios.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): How was the frequency response in early recordings?
very irregular