In this second and closing instalment we get real with two times 32 NE5532 opamps paralleled to form a high-end audio power amplifier with eminent specifications in terms of distortion and general sonic performance. There are also challenges for you: bridged operation for higher output power, and modifying the amplifier for 4-ohm operation.
Specification — per channel, 8 ohm load
Supply voltage: ±18.3 V
Input sensitivity
- unbalanced: 840 mV (16 W, 1 % THD)
- balanced: 833 mV (16 W, 1 % THD)
Input impedance
- unbalanced: 38.8 kOhm
- balanced: 93.6 kOhm
Output power, sinewave
- 0.1 % THD: 16 W
- 1 % THD: 16.8 W
Output power bandwidth: 1.5 Hz – 275 kHz
Slew rate: 5 V/µs
Rise time: 4 µs
Signal/noise ratio: (1 W ref.): 110 dBA
- 108 dB (B = 22 Hz – 22 kHz linear/unweighted)
Harmonic distortion + noise: 0.00055 % 0.0005% (B = 22 kHz, 1 kHz, 1 W)
- 0.0015 % 0.0009% (B = 80 kHz, 1 kHz, 1 W)
- 0.0006 % 0.0004% (B = 22 kHz, 1 kHz, 8 W)
- 0.0008 % 0.0005% (B = 80 kHz, 1 kHz, 8 W)
- 0.003 % (B = 80 kHz, 20 kHz, 8 W)
Intermodulation distortion: 0.0022 % 0.0012% (1 W)
- (50 Hz : 7 kHz = 4 : 1): 0,005 % 0.0015% (8 W)
Dynamic IM distortion: 0.0014 % 0.0011% (1 W)
- (3.15 kHz square wave + 15 kHz sine wave): 0.0035 % 0.0035% (8 W)
Damping factor: 194 (1 kHz)
- 111 (20 kHz)
DC-protection: ±1.5 V
Quiescent current : 300 mA
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