Parasound Halo A21+ Stereo Power Amplifier
The Halo A 21+ power amplifier is a pinnacle of power and fidelity
The 21+ has two channels providing 250 watts per channel into 8 Ω, it delivers breathtaking audio performance. The high bias Class A/AB operation ensures accurate and detailed sound reproduction, while the stable operation into 2 Ω loads allows for versatility in speaker configurations. The direct-coupled design, free from capacitors in the signal path, preserves signal integrity and enhances transparency. With balanced XLR and unbalanced RCA inputs and A/B speaker terminals, it offers flexibility and compatibility. Experience pure power and fidelity with the Halo A 21+ power amplifier.
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
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
Specifications
| Power Output – Stereo Mode (0.1% THD) | 300 watts x 2, 8 Ω both channels driven 500 watts x 2, 4 Ω both channels driven |
| Power Output – Bridged Mode (0.1% THD) | 1000 watts x 1, 8 Ω Bridged 4 Ω operation is not recommended |
| Current Capacity | 60 amps peak, per channel |
| Slew Rate | > 130 volts per microsecond |
| Frequency Response | 5 Hz - 100 kHz, +0/-3 dB 20 Hz - 20 kHz, +0/-0.25 dB |
| Total Harmonic Distortion (THD) | < 0.1 % at full power < 0.03 % at typical listening levels |
| IM Distortion | < 0.04 % |
| TIM | Unmeasurable |
| Inter-channel Crosstalk | > 80 dB at 1 kHz > 70 dB at 20 kHz |
| Input Impedance | Unbalanced: 33 kΩ Balanced: 66 kΩ (33 kΩ per leg) |
| Total Gain | 29 dB |
| Input Sensitivity for 28.28 V Output into 8 Ω | Unbalanced: 1 V Balanced: 1 V per leg |
| S/N Ratio | > 115 dB, input shorted, IHF A-weighted > 110 dB, input shorted, unweighted |
| Damping Factor | > 1100 at 20 Hz |
| DC Trigger Requirements | +9 Vdc to +12 Vdc, 5 mA |
| Audio Trigger Requirements | 2 mV - 10 mV |
| XLR Pin Identification | 1 = Ground (Shield) 2 = Positive 3 = Negative (Return) |
| Dimensions | Width: 17-5/8" (448 mm) Height without feet: 7-1/8" (181 mm) Height with feet: 7-3/4" (197 mm) Depth: 20" (508 mm) Depth with cables: 21-1/2" (546 mm) |
| Net Weight | 71 lb. (32.2 kg) |
| Shipping Weight | 88 lb. (39.9 kg) |
| Power Requirement | Standby: 1 Watt Idle (no music playing): 160 Watts Typical Listening levels: 300 Watts Maximum: 1400 Watts |
Parasound Reviews
Parasound Halo A21+ Stereo Power Amplifier
Sale price$4,199
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