# Gain of the system of amplifiers

#### Tino

I need help with the two questions below please because i just don't understand it !!!1

Questions
1. A signal processing system consists of a preamplifier, an amplifier and a filter connected in series. At a given frequency the preamplifier and the amplifier have gains of 12 dB and 31 dB respectively, while the input and output voltages of the filter are 7.0 v and 0.35v respectively. Calculate the overall gain of the system at that frequency.

2. A rock band produces music with a bandwidth from 30Hz to 20kHz. If the music is amplified through a system with the following bandwidths what range of frequencies will be heard by the audience.

Microphones (10Hz to 12khz), Amplifiers (45Hz to 16kHz), Loudspeakers (50Hz to 14kHz).

Thanks !!!!

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#### Tino

I think i have cracked it !!!

1. voltage gain/loss = 20log V1/V2 = 20log (0.35/7) = - 26dB

And the overall gain is 12dB - 26dB + 31dB = 17dB

2. The audience would hear around 50Hz - 14kHz.

I don't know if my answers are corrected, if it isn't can u please corrected me .

#### OlderDan

Homework Helper
Tino said:
1. voltage gain/loss = 20log V1/V2 = 20log (0.35/7) = - 26dB

And the overall gain is 12dB - 26dB + 31dB = 17dB

2. The audience would hear around 50Hz - 14kHz.

I don't know if my answers are corrected, if it isn't can u please corrected me .

#1 looks good to me. #2 does not. How is a 14kHz signal going to get to the speakers?

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