description
In store sales only
Parasound's new Halo A 21+ delivers a whopping 300 watts per channel, and it's stable enough to drive just about any speakers you might care to hook up.
Convenient connections
On the back panel are balanced XLR and unbalanced RCA inputs for each channel, and each has its own individual gain control knob and loop output. There are also binding posts for connecting a pair of speakers. The amp can be rack mounted using the included ears.
Class A/AB operation for smoother sound
Engineers and audiophiles generally agree that Class A designs offer the purest sound, but they tend to run hot and take up a lot of space. As a result, home audio amplifiers often use a compromise known as Class AB, which hands off part of the audio signal to a different set of output transistors at high power levels. AB can sacrifice a bit of signal purity, but it lets the amp run cooler and more efficiently.
This Class A/AB amp operates in pure Class A mode up to a higher power level than most other amplifiers in its price category, before the second set of transistors kick in. The result is a sound that's smoother, less fatiguing, and more natural.
The legacy of John Curl
The A 21+ features circuitry designed by John Curl, a legend in audio engineering. He started his career in the 1970s, designing tape and video recorders at Ampex, and he had a hand in building the Grateful Dead's famous Wall of Sound. Curl has worked with Parasound since 1989, designing all of their high-power amplifiers and more. The power supply, transistors, capacitors and other parts in the A 21+ were chosen to offer high performance at a reasonable price.
Power Output Stereo Mode (0.1% THD)
300 watts x 2, 8 Ohm both channels driven
500 watts x 2, 4 Ohm both channels driven
Power Output Bridged Mode (0.1% THD)
1000 watts x 1, 8 Ohm
Bridged 4 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 k Ohm
Balanced: 66 k Ohm ,(33 k Ohm per leg)
Total Gain
29 dB
Input Sensitivity for 28.28 V Output into 8
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
