A 52+

  • 180 watts RMS x 5 @ 8 Ω
  • 255 watts RMS x 5 @ 4 Ω
  • 225 watts RMS x 2 @ 8 Ω
  • 350 watts RMS x 2 @ 4 Ω
  • Class A/AB circuitry designed by legendary John Curl
  • Direct coupled - no capacitors or inductors in audio path ensures the cleanest signal
  • Balanced XLR inputs with discrete circuits
  • Full power is rated all the way down to 5Hz for unrestricted low-end bass
  • Custom 1.5 kVA encapsulated toroid power transformer with independent secondary windings for each channel
  • Hand-matched JFETs for input stage
  • Hand-matched MOSFETs for driver stage
  • Beta-matched 15 amp, 60 MHz bipolar output transistors (3 pairs per channel)
  • 100,000 µF power supply filter capacitance
  • DC Servo and relay protection circuits
  • Auto turn on by audio signal or 12V trigger
  • Heavy-duty 24k gold-plated, 5-way speaker terminals
  • 3U chassis with updated cosmetics, rack mountable with HRA3 (sold separately)

Power Output - All 5 Channels Driven
180 watts x 5, 8 Ω
255 watts x 5, 4 Ω

Power Output - 2 Channels Driven
225 watts x 2, 8 Ω
350 watts x 2, 4 Ω

Power measurements parameters with 120VAC
0.05% THD, RMS continuous power,
full audio band (20 Hz - 20 kHz)

Current Capacity:
45 amperes peak, per channel

Dynamic Headroom:
>1.5dB

Slew Rate
> 130 volts per microsecond

Frequency Response
5 Hz - 100 kHz, +0/-3 dB
20 Hz - 20 kHz, +0/-0.3 dB

Total Harmonic Distortion (THD)
< 0.05 % at full power
< 0.03 % at typical listening levels

IM Distortion
< 0.04 %

TIM
Unmeasurable

Interchannel Crosstalk
> 78 dB at 1 kHz
> 63 dB at 20 kHz

Input Impedance
Unbalanced: 47 kΩ
Balanced: 94 kΩ, 47 kΩ per leg

Input Sensitivity for 28.28 V Output into 8 Ω
Unbalanced: 1 V
Balanced: 1 V per leg
Total Gain: 29 dB

S/N Ratio
> 112 dB, input shorted, IHF A-weighted
> 102 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: 17-1/4" (437 mm)
Height without feet: 5-1/4" (133 mm)
Height with feet: 5-7/8" (149 mm)
Depth: 20" (508 mm)
Depth with cables: 21-1/4" (540 mm)

Net Weight
55 lb. (25 kg)

Shipping Weight
69 lb. (31.3 kg)

Power Requirement
Standby: 1 Watt
Idle: 125 Watts
Maximum: 1500 Watts

Reviews coming soon.

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