Circuits for transducers (for stereophonic arrangements H 04 R 5/04; arrangements for producing a reverberation or echo sound G 10 K 15/08; amplifiers H 03 F)
3
/
02
•
for preventing acoustic reaction
3
/
04
•
for correcting frequency response
3
/
06
•
•
of electrostatic transducers
3
/
08
•
•
of electromagnetic transducers
3
/
10
•
•
of variable-resistance microphones
3
/
12
•
for distributing signals to two or more loud-speakers
