Impressive Performance Upgrades

The performance upgrades are impressive, beginning with a big 25% to 30% increase in output power compared to the previous model. The A 23+ delivers 160 watts-per-channel at 8 ohms compared to 125 watts-per-channel for the A 23, 240 watts-per-channel compared to 225 watts-per-channel at 4 ohms, and 500 watts in bridged mono mode compared to 400 watts with the A 23.

The performance of a power amplifier is highly dependent on the quality of its power supply, and Parasound went the extra mile with the A 23+, which boasts a 10% to 15% larger main power transformer compared to the previous model A 23. Transformer size has been increased from 1.0 to 1.1kVA, and the filter capacitance increases 20-30% from 40,000 uF for the A 23 to 54,400 uF for the new A 23+. You'll hear the advantages of these upgrades as the A23+ presents lower distortion at full power.

Other performance upgrades include tweaked input circuits for improved crosstalk specs (70 dB at 20 kHz compared to 63 dB) and upgraded internal gold on gold audio connections, resulting in a cleaner signal path that's also more reliable.

Rear Panel Layout and Features Upgrades

The rear panel of the A 23+ has been revised in terms of layout and new features. It boasts upgraded speaker terminals, using identical terminals to the HINT 6 integrated amp, a new jack/terminal layout with more space and more clear text/labels, and a master "Vacation" AC switch. The 2.5mm trigger jacks of the A 23 have been replaced with 3.5mm jacks, and the audio trigger circuit has been updated for better low signal reliability.

Changes from The Original A 23→A 23+

- 125 → 160 Watts @ 8Ω

- 225 → 240 Watts @ 4Ω

- 400 → 500 Watts when bridged

- Filter cap: 40,000 uF →54,400 uF

- Crosstalk ( 20kHz ): 63dB → 70dB

- Transformer size: 1.0 kVA → 1.1 kVA

- Refined Halo cosmetic with aluminum end caps & gold highlights

- Updated rear panel with heavy duty speaker terminals from HINT 6

- Upgraded internal gold on gold audio connections

- Updated auto turn on circuit

Features

- 160 watts x 2 @ 8 Ω RMS, both channels driven

- 240 watts x 2 @ 4 Ω RMS, both channels driven

- 500 watts x 1 @ 8 Ω, in bridged mode

- Circuitry designed by legendary John Curl

- High bias Class A/AB operation

- 45 amperes peak current per channel

- Stable with speaker impedance dips below 2 Ω

- Balanced inputs with discrete circuits

- Heavy-duty 24k gold-plated 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

- 12 beta-matched 15 ampere, 60 MHz bipolar output transistors

- 1.1 kVA shielded toroid transformer w/ independent windings for each channel

- Independent power supplies for input stage, driver stage and output stage

- 54,400 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

- 2 rack space chassis with rear carry handles

- Rack mount hardware available separately

- Available in silver or black

Parasound A 23+ Halo Amplifier User's Manual

Specifications

Power Output – Stereo Mode (0.06% THD)
160 watts x 2, 8 Ω both channels driven
240 watts x 2, 4 Ω both channels driven

Power Output – Stereo Mode (0.9% THD)
210 watts x 2, 8 Ω both channels driven
300 watts x 2, 4 Ω both channels driven

Power Output – Bridged Mode (0.06% THD)
500 watts x 1, 8 Ω
Bridged 4 Ω operation is not recommended

Power Output – Bridged Mode (0.9% THD)
600 watts x 1, 8 Ω
Bridged 4 Ω operation is not recommended 

*All Power measurement are at 120 VAC,
RMS continuous power, full audio band ( 20 Hz - 20 kHz )

Current Capacity: 45 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
< 0.06 % at full power
< 0.03 % at typical listening levels

IM Distortion: < 0.04 %

TIM: Unmeasurable

Inter-channel Crosstalk
> 85 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 Out @ 8 Ω Load
Unbalanced: 1 V
Balanced: 1 V per leg

S/N Ratio
> 112 dB, input shorted, IHF A-weighted
> 107 dB, input shorted, unweighted

Damping Factor: > 800 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" 
Depth: 15^1/4"
Depth, with cables 17" 
Height, with feet: 4^1/8"
Height, without feet: 3 ^1/2" , 2U

Net Weight: 27 lb.

Shipping Weight: 34 lb.

Power Requirement
Standby: <1 Watt 
Idle ( no music playing ): 75 Watts 
Typical Listening levels: 125 Watts
Maximum: 800 Watts
110-125 VAC 60 Hz or 220-250 VAC 50 Hz
AC mains voltage is set on rear panel