Benchmark AHB2 Power Amplifier

The AHB2 is a radically different audio amplifier. Its patented design delivers performance that approaches the limits of the latest high-resolution audio formats. Benchmark's AHB2 power amplifier delivers musical details without introducing the masking effects of amplifier noise and distortion. The dynamic range of the AHB2 is 132 dB, making it 10 to 30 dB quieter than some of the very best reference-quality power amplifiers.

Unlike class-D amplifiers, the AHB2 is noise free over its entire 0.1 Hz to 200 kHz frequency range. Don't settle for the limited performance of class-D amplification.

With the AHB2, you will discover previously overlooked nuances, dynamics, and detail in your favorite recordings and experience the full potential of the latest high-resolution 24-bit PCM and 1-bit DSD audio formats.

Sonic Purity that Surpasses Class A!

The AHB2 is a linear amplifier that surpasses the sonic purity of all class-A amplifiers. No amplifier delivers lower noise or lower distortion. The small, passively cooled chassis, cleanly delivers 480 Watts bridged mono into 6 Ohms, with additional reserves for driving difficult speaker loads. Unlike power-hungry class-A amplifiers, the AHB2 achieves a power efficiency that rivals that of a Class D (switching) power amplifier.

Difficult Speaker Loads are Handled With Ease

Many loudspeakers have frequencies at which their impedance drops to levels that are much lower than the "nominal" impedance. The AHB2 drives difficult phase angles and low impedances with ease. Stereo loads as low as 1.4 Ohms can be cleanly driven to full output levels. Most power amplifiers produce higher levels of distortion when the load impedance decreases. In contrast, the feed-forward error correction system in the AHB2 keeps the output clean when driving difficult loads. The AHB2 produces almost no measurable distortion at any rated load condition.

High Damping Factor

The AHB2 has a high damping factor that augments its extended low-end to deliver solid, well-controlled bass. This high damping factor also keeps the frequency response absolutely flat while driving speakers with large frequency-dependent impedance variations.

High Output Current

The AHB2 can deliver up to 29 A peak to each channel simultaneously. This robust drive current easily handles some of the most demanding loudspeakers. The AHB2 has tightly regulated power supplies that keep the output clean while delivering high current.

Distortion is Below Audibility

The AHB2 will never produce audible distortion. In most playback systems, the distortion produced by the AHB2 will never even reach the 0 dB SPL threshold of hearing. This means that the distortion could not be heard, even if it could be played while the music was muted.

The AHB2 allows you to escape the distortion limitations of classic amplifier topologies and enter the world of high-resolution audio playback.

Continuous Average Output Power

< 0.0003 % THD+N at full rated power, 20 Hz to 20 kHz

• 100 Watts per channel into 8 Ohms, both channels driven
• 130 Watts per channel into 6 Ohms, both channels driven
• 190 Watts per channel into 4 Ohms, both channels driven
• 240 Watts per channel into 3 Ohms, both channels driven
• 259 Watts per channel into 2 Ohms, both channels driven
• 200 Watts into 16 Ohms, bridged mono
• 380 Watts into 8 Ohms, bridged mono
• 480 Watts into 6 Ohms, bridged mono
• 518 Watts into 4 Ohms, bridged mono

All speakers have variations in input impedance. Select loads based on nominal impedances not minimum impedances. The AHB2 is stable into all loads. The AHB2 is conservatively rated at an output level where THD+N is < 0.0003 % instead of the more typical 1% THD+N. Power at 1% THD will be higher.

Output Voltage Into Various Load Impedances

< 0.0003% THD+N at the following output voltages and load impedances, 20 Hz to 20 kHz

• 29.03 dBV, 31.25 dBu, 28.28 Vrms into 8 Ohms, both channels driven
• 28.92 dBV, 31.14 dBu, 27.93 Vrms into 6 Ohms, both channels driven
• 28.81 dBV, 31.03 dBu, 27.57 Vrms into 4 Ohms, both channels driven
• 28.57 dBV, 30.79 dBu, 26.83 Vrms into 3 Ohms, both channels driven
• 27.14 dBV, 29.36 dBu, 22.76 Vrms into 2 Ohms, both channels driven
• 35.05 dBV, 37.27 dBu, 56.57 Vrms into 16 Ohms, bridged mono
• 34.83 dBV, 37.05 dBu, 55.14 Vrms into 8 Ohms, bridged mono
• 34.59 dBV, 36.81 dBu, 53.67 Vrms into 6 Ohms, bridged mono
• 33.16 dBV, 35.38 dBu, 45.52 Vrms into 4 Ohms, bridged mono

Use dBV to calculate the peak SPL from your speaker/amplifier combination. Use the following formula: Amplifier output voltage in dBV + speaker sensitivity at 2.83V - 9 dB. Example: (29.03 dBV at 8 Ohms) + (90 dB SPL @ 2.83V 1m) - 9 dB = 110 dB SPL at 1 meter

SNR & Dynamic Range

Rated output relative to output noise, inputs shorted

• 132 dB A-weighted, Stereo Mode
• 135 dB A-weighted, Mono Mode
• 130 dB Unweighted, 20 Hz to 20 kHz, Stereo Mode
• 133 dB Unweighted, 20 Hz to 20 kHz, Mono Mode

Noise Voltage

Output noise voltage, A-weighted, inputs shorted

• -103 dBV, -101 dBu, 7.1 uVrms, Stereo Mode
• -100 dBV, -98 dBu, 9.8 uVrms, Mono Mode

Use dBV to calculate the SPL of the noise produced by your speaker/amplifier combination. Use the following formula: Amplifier output noise voltage in dBV + speaker sensitivity at 2.83V - 9 dB. Example: Mono mode driving very high efficiency speakers: (-100 dBV) + (104 dB SPL @ 2.83V 1m) - 9 dB = -5 dB SPL at 1 meter. This means that the system noise will be 5 dB below the threshold of hearing when driving speakers with a very high 104 dB efficiency. The noise will be even further below the threshold of hearing when driving typical speakers.

Noise Relative to 2.83 Vrms (1 Watt into 8 Ohms)

Output noise relative to 2.83 Vrms, A-weighted, inputs shorted

• -112 dB, Stereo Mode
• -109 dB, Mono Mode

THD+N

1 kHz, 80 kHz LPF, at full rated output into any rated load

• < -118 dB (< 0.00013%), Stereo Mode
• < -118 dB (< 0.00013%), Mono Mode

THD

1 kHz, 20 kHz LPF, at full rated output into any rated load

• < -119 dB (< 0.00011%), Stereo Mode
• < -120 dB (< 0.00010%), Mono Mode

Crosstalk

• Better than -115 dB at 1 kHz
• Better than -92 dB at 20 kHz

Frequency Response

• Better than 0.1 Hz to 200 kHz, +0/-3 dB
• -0.01 dB at 20 Hz, -0.17 dB at 20 kHz, 8-Ohm Load
• -0.23 dB at 20 Hz, -0.32 dB at 20 kHz, 4-Ohm Load

Damping Factor

• 350 at 20 Hz, 8-Ohms
• 254 at 1 kHz, 8-Ohms
• 34 at 20 kHz, 8-Ohms
• 7 at 200 kHz, 8-Ohms

Maximum Audio Output Current

• 29 A peak, per channel, both channels driven

Input Sensitivity

• Low-Gain = 22 dBu (9.8 Vrms), Gain = 9.2 dB
• Mid-Gain = 14.2 dBu (4 Vrms), Gain = 17.0 dB
• High-Gain = 8.2 dBu (2 Vrms), Gain = 23 dB
• Use Mid-Gain or High-Gain settings for unbalanced inputs

Input Impedance

• 50 k Ohms, normal mode
• 1 M Ohm, common mode

Input CMRR

• 80 dB at 20 Hz, typical
• 80 dB at 1 kHz, typical
• 65 dB at 20 kHz, typical

Trigger I/O

• 12 VDC 200 mA current-limited output to trigger turn-on of remote devices
• DC input for slaving to remote devices
• Input responds to 3.3 V logic and higher, VIL = 1.26 V, VIH = 2.7 V
• Absolute maximum input voltage = 30 VDC
• Absolute minimum input voltage = -0.3 VDC
• Input Impedance = 20 k Ohms

Protection Circuits

• Fully Electronic, No Relays
• Mute Sequencing
• Distortion Detection
• Short Circuit Detection
• Over Current Detection
• Over Temperature Detection
• SOA Detection (Output device safe operating area)

Dimensions

Non-rack-mount version:

• 11.04" W x 3.88" H x 9.34 " D - Including feet and binding posts
• 11.04" W x 3.47" H x 8.33 " D - Excluding feet and connectors
• Faceplate height is 2RU

Rack-mount version:

• 19.00" W x 3.88" H x 10.62 " D - Including binding posts, handles and removable feet
• 19.00" W x 3.47" H x 8.33 " D - Excluding feet and connectors
• 9.09" rack depth, including binding posts, excluding cables
• 11" rack depth, including cables
• Faceplate height is 2RU

Weight

• 12.5 lbs., 16 lbs. shipping - Non-rack-mount version
• 13.5 lbs., 17 lbs. shipping - Rack-mount version

AC Input

• Auto-ranging AC Input
• 100 to 120 VAC +/- 10%, 8 Amps, 50 - 60 Hz
• 220 to 240 VAC +/- 10%, 8 Amps, 50 - 60 Hz
• Idle Power Consumption = 20 W
• Standby Power Consumption < 0.5 W