HALO A31 3-Channel Power Amp
Power You Can Feel
Drop the A31 into your system and everything locks in: voices stand center‑stage, low end digs deeper without bloat, and effects surge with head‑turning impact. It’s the missing muscle your movies and music have been asking for.
Designed by legendary audio engineer John Curl, it runs high‑bias Class A/AB (the first ~7 watts in pure Class A) with a direct‑coupled signal path for maximum clarity. A 1.5 kVA toroidal transformer and 98,400 µF of filter capacitance supply clean current on demand, while 250 W x3 into 8 Ω (400 W x3 into 4 Ω), balanced XLR and RCA inputs, and THX Ultra2 certification make integration straightforward in serious home theaters.
Praised by audiophiles and reviewers alike:
- “Clear, detailed sound that belies its price…a joy to listen to.” — SoundStage! Access (Reviewers’ Choice)
- “Impeccable in fit and finish…powerful but refined.” — Secrets of Home Theater & High Fidelity
Awards & Recognition
- Stereophile — Recommended Components (2012, Surround‑Sound Components).
- SoundStage! Access — Reviewers’ Choice (2015).
- Secrets of Home Theater & High Fidelity — Best of 2012: Best Multichannel Amplifier.
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.
- 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
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."