Parasound A21+ stereo power amplifier

Changes compared to the A 21→A 21+

• 250 → 300 watts (8Ω)
• 400 → 500 watts (4Ω)
• 750 → 1000 watts (bridged)
• Filter cap: 88.000uF → 108.000uF
• S/N: 112dB → 115dB
• THD (at full power): 0.2% → 0.1%
• Crosstalk (20kHz): 63dB → 70dB
• Transformer Size: 1,2kVA → 1,3kVA
• Weight: 27,22kg → 32,21kg
• Refined halo design with aluminum end caps and gold accents
• Updated rear panel with high performance JC 5 speaker terminals
• Upgraded internal gold-on-gold audio connectors
• Updated auto power on circuit

All features

• 300 watts x 2 @ 8 Ω RMS, both channels driven
• 500 watts x 2 @ 4 Ω RMS, both channels driven
• 1000 watts x 1 @ 8 Ω, in bridged mode
• The circuit was developed by the legendary John Curl
• Class A/AB operation with high bias
• 60 amps peak current per channel
• Stable with speaker impedance drops up to 1,5 Ω
• Balanced inputs with discrete circuits
• CHK Infinium, custom 5-way speaker terminals
• Gold plated RCA input and loop out jacks
• Directly coupled signal path, no capacitors or inductors
• DC servo and relay protection circuits
• AC inrush protection with relay bypass
• JFET input stage, MOSFET driver stage
• 16 beta-matched 15 amp, 60 MHz bipolar output transistors
• 1,3 kVA shielded toroidal transformer with independent windings for each channel
• Independent power supplies for input stage, driver stage and output stage
• 108.000 µF filter capacitors for the output stages
• Full power down to 5 Hz for unrestricted deep bass
• Hyper-fast Harris bridge rectifiers with soft-recovery diodes
• Automatic switch-on by 12 V trigger or audio sensors
• 4-rack case with carrying handles on the back
• Rack mounting hardware is included