radio receivers

television receivers

tape recorders

all the above stated systems

a power amplifier and loudspeakers

an audio mixer and a tone control

microphones and pre-amplifiers

all the above stated systems

insulated

shielded

short lengthed

fibre

woofer

tweeter

squawker

booster

for large voltage amplification

for current amplification

to avoid loading effect of the signal source

for all the purposes stated above