250 watts x 3 @ 8 Ohms / 400 watts x 3 @ 4 Ohms
Adjustable gain for up to +6db over THX Reference level
Unbalanced RCA and balanced XLR inputs
Circuitry designed by legendary John Curl
High bias class A/AB operation
Direct coupled (no capacitors or inductors in signal path)
Complementary MOSFET driver stage and JFET input stage
24 beta-matched 15 amp, 60 MHz bipolar output transistors
1.5 kVA encapsulated toroid power transformer with independent
secondary windings for each channel
98,400 µF power supply filter capacitance
DC Servo and relay protection circuits
AC present, channel status, high temperature indicators
Heavy-duty 24k gold-plated 5-way speaker terminals
THX Ultra2 certified
Auto turn-on by 12v trigger or audio signal
4u Chassis, carry handles, rack mounting adapter included
Continuous power output:
250 watts RMS x 3, 20 Hz - 20 kHz, 8 Ω, all channels driven
400 watts RMS x 3, 20 Hz - 20 kHz, 4 Ω, all channels driven
Current capacity:
60 amperes peak per channel
Power bandwidth:
5 Hz - 100 kHz, +0/-3 dB at 1 watt
Total harmonic distortion:
< 0.2 % at full power
IM distortion: balanced 16 V rms
< 0.04 %
Slew rate:
> 130 V/µsecond
Dynamic headroom:
> 1.5 dB
Interchannel crosstalk:
> 78 dB at 1 kHz;
> 63 dB at 20 kHz
Input sensitivity:
1 V for 28.28 V (THX Reference)
Input impedance:
47 k Ω unbalanced; 94 k Ω balanced
S/N ratio:
112 dB, input shorted, IHF A-weighted
Damping factor:
> 1100 at 20 Hz
Dimensions:
17-1/2" w x 7-5/8" h x 20" d, 7" h without feet
Net weight: 65 lb.
Shipping weight: 79 lb.
Soundstage Access April 2015
"The Halo A 31 has a clear, detailed sound that belies its price, combined with just a touch of warmth. This blend of qualities made it a joy to listen to. Add to that its prodigious power output and rock-solid build quality, and I can assure you: It's the real deal."
Secrets of Home Theater and High Fidelity
"The Halo A 31 is a wonderful amplifier. By staying out of the way and letting me enjoy the music, the A 31 made this review a challenge to find new ways to say that it sounded wonderful. The Halo A 31 is able to drive any speaker you are going to throw at it and not complain, as well as impeccably built and beautiful in appearance."
Stereophile September 2012
"Remarkable definition…clean, luminous sound. Firm and extended bass. Running full range and full bore, I never lacked for power and weight."
