Changes from the original A 21→A 21+
- 250 → 300 Watts (8Ω)
- 400 → 500 Watts (4Ω)
- 750 → 1000 Watts (bridged)
- Filter cap: 88,000 uF → 108,000 uF
- S/N: 112dB → 115 dB
- THD (at full power): 0.2% → 0.1%
- Crosstalk (20kHz): 63dB → 70dB
- Transformer size: 1.2 kVA → 1.3 kVA
- Weight: 60 LB → 71 LB
- Refined Halo cosmetic with aluminum end caps & gold highlights
- Updated rear panel with heavy duty speaker terminals from JC 5
- Upgraded internal gold on gold audio connections
- Updated auto turn 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
- Circuitry designed by legendary John Curl
- High bias Class A/AB operation
- 60 amperes peak current per channel
- Stable with speaker impedance dips to 1.5 Ω
- Balanced inputs with discrete circuits
- CHK Infinium, custom 5-way speaker binding posts
- Gold-plated RCA input & loop output jacks
- Direct-coupled signal path, no capacitors or inductors
- DC Servo and relay protection circuits
- AC turn-on inrush surge protection with relay bypass
- JFET input stage, MOSFET driver stage
- 16 beta-matched 15 ampere, 60 MHz bipolar output transistors
- 1.3 kVA shielded toroid transformer w/ independent windings for each channel
- Independent power supplies for input stage, driver stage and output stage
- 108,000 µF filter capacitors for output stages
- Full power is rated all the way down to 5Hz for unrestricted low-end bass
- Harris hyper-fast soft-recovery bridge diode rectifiers
- Automatic turn-on by 12 V trigger or audio sensing
- 4 rack space chassis with rear carry handles
- Rack mount hardware is included
- Available in silver or black
