Oceana Audio Power Amplifiers

Design Equations

[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 W60 W25 W
Rl (Resistive load, Ohm)8 Ohm8 Ohm8 Ohm

Output Voltage

   
Erms (RMS output voltage, Volts)
= sqrt( Prms Rl )
28.3 V21.9 V14.1 V
Epeak (Peak output voltage, Volts)
= sqrt( 2 ) Erms
40.0 V31.0 V20.0 V
Esupply (Supply voltage, Volts)
~= Epeak x 1.15
to allow for device and resistive drops
46 V36 V23 V

Eac (Power Transformer AC voltage, Volts)
~= ( Esupply + 2 ) / sqrt( 2 )
to allow for rectifier drops

34 V28 V18 V

Output Stage Current

   
Irms (RMS current, Amps)
= sqrt( Prms / RL )
3.5 A2.7 A1.8 A
Ipeak (Peak current, Amps)
= sqrt( 2 ) Irms
5 A3.9 A2.5 A

Iq (Quiescent current, Amps)
= Ipeak / 2

2.5 A1.95 A1.25 A

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© 1999 Glenn Baddeley.
http://home.pacific.net.au/~gnb/audio/adesign.html was last updated 13 December 1999.
Report problems and send comments to Glenn Baddeley.