Oceana Audio Power Amplifiers

[Glenn's Audio and Hi-Fi Page] [A25 Amplifier] [A60 Amplifier] [A100 Amplifier]

Design Equations

These equations are presented as a general procedure for the design of the major power supply and current parameters of these Class A power amplifiers. The allowed-for losses are approximate. A reactive "loudspeaker" load and "musical" voltage waveforms will increase the current requirements. sqrt( ) means the square root of whatever is contained within the parentheses.

Requirements	Model A100	Model A60	Model A25
Prms (RMS power output, Watts)	100 W	60 W	25 W
Rl (Resistive load, Ohm)	8 Ohm	8 Ohm	8 Ohm
Output Voltage
Erms (RMS output voltage, Volts) = sqrt( Prms Rl )	28.3 V	21.9 V	14.1 V
Epeak (Peak output voltage, Volts) = sqrt( 2 ) Erms	40.0 V	31.0 V	20.0 V
Esupply (Supply voltage, Volts) ~= Epeak x 1.15 to allow for device and resistive drops	46 V	36 V	23 V
Eac (Power Transformer AC voltage, Volts) ~= ( Esupply + 2 ) / sqrt( 2 ) to allow for rectifier drops	34 V	28 V	18 V
Output Stage Current
Irms (RMS current, Amps) = sqrt( Prms / RL )	3.5 A	2.7 A	1.8 A
Ipeak (Peak current, Amps) = sqrt( 2 ) Irms	5 A	3.9 A	2.5 A
Iq (Quiescent current, Amps) = Ipeak / 2	2.5 A	1.95 A	1.25 A

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