GeorgeBynum
Active Member
I'm a little confused by gain figures as used in the HiFi audio (particularly amplifier) industry.
I __BELIEVE__ I have an excellent understanding of gain and log measurements (Bel and deciBel) as an electrical/electronic engineer involved, working in college 50 years ago, in the rf communications transceiver design/manufacturing/testing industry.
Let me explain my confusion.
Say I have an amplifier with purely resistive input Z of 10k ohms, not unusual. It is driving a perfect speaker with purely resistive load Z of 4 ohms.
I input 1V RMS (2.83 P-P, but that's not the issue, just acknowledging the 2*root2 relationship). The input power is 0.1 mW.
ASSUME the output to the speaker is also 1V RMS. The output power is 250 mW.
The gain of this amplifier is 2500 (250 mW/0.1 mW) or 34 dB.
I get the impression that the HiFi industry defines this amplifier gain as 0 dB based only on input and output signals.
Will some smart person explain the mistakes in my logic, or explain what someone like NCore means when they advertise gain figures? Do input and output power relationships get any consideration?
I __BELIEVE__ I have an excellent understanding of gain and log measurements (Bel and deciBel) as an electrical/electronic engineer involved, working in college 50 years ago, in the rf communications transceiver design/manufacturing/testing industry.
Let me explain my confusion.
Say I have an amplifier with purely resistive input Z of 10k ohms, not unusual. It is driving a perfect speaker with purely resistive load Z of 4 ohms.
I input 1V RMS (2.83 P-P, but that's not the issue, just acknowledging the 2*root2 relationship). The input power is 0.1 mW.
ASSUME the output to the speaker is also 1V RMS. The output power is 250 mW.
The gain of this amplifier is 2500 (250 mW/0.1 mW) or 34 dB.
I get the impression that the HiFi industry defines this amplifier gain as 0 dB based only on input and output signals.
Will some smart person explain the mistakes in my logic, or explain what someone like NCore means when they advertise gain figures? Do input and output power relationships get any consideration?