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Review on FutureAudiophile.com

 

Features 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

Parasound A 21+ 2-Channel Amplifier

$3,999.00Price
Color
In-Store Only/Call to Purchase

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

Power measurement are at 120 VAC:
0.1% THD, RMS continuous power,
full audio band (20 Hz - 20 kHz)

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

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