Zapco HB 48 II 4A — 8-Channel DSP with 4-Channel Amplifier

Zapco HB 48 II 4A — 8-Channel DSP with 4-Channel Amplifier

The HB 48 II 4A combines an 8-channel digital signal processor with a 4-channel Class AB amplifier. Amplifier output is 23 watts RMS per channel at 4 ohms, 35 watts per channel at 2 ohms, with a maximum of 70 watts per channel.

Signal-to-noise is better than 100dB with THD under 0.05%, across a 20Hz to 20kHz bandwidth.

Eight Processed Channels, Four Amplified

The difference between this and the HB 46 II 4A is channel count on the processing side: eight DSP channels and eight RCA outputs rather than six. Amplification is identical.

That matters for system architecture. Eight processed outputs cover a three-way active front stage plus a subwoofer channel, or a two-way front with rear fill and bass — with the onboard amplifier handling whichever four channels suit its output and external amplification taking the rest.

Four channels of high-level speaker input and two RCA inputs feed the processor, with input impedance of 20 kilohms low and 22 ohms high.

Factory Source Integration

High-level input takes signal directly from a factory head unit or factory amplifier — the situation where processing does the most work, since factory systems arrive with equalisation and delay applied that a DSP can measure and reverse.

Input selection covers Aux, Bluetooth, high level, the app player, and OTG. Bluetooth streaming is available through an optional external module.

Processing Tools

• Equalizer: 31 bands
• Crossover types: Butterworth, Bessel, Linkwitz-Riley
• Crossover slope: 6 to 48 dB/octave
• I/O mixing matrix: yes
• Tuning: PC software and app

The slope range from 6 to 48 dB per octave covers gentle overlapping filters through to steep separation, so the crossover can be matched to the drivers and their mounting positions rather than the reverse.

The I/O mixing matrix routes any input to any output — which is what makes a factory source usable when it distributes frequencies across channels in ways your system design does not follow.

System Application

A three-way active front stage plus subwoofer, processed in one chassis, with the built-in amplifier driving the drivers it suits and external amplification handling the rest.

Twenty-three watts per channel is modest by design. This unit is bought for its eight channels of processing; the amplification covers efficient drivers or supplements a larger system.

Installation Considerations

Plan which four channels the onboard amplifier drives. With eight processed outputs and four amplified, that assignment is a design decision — typically the amplifier takes the tweeters and midrange while external amplification handles midbass and subwoofer.

Supply voltage is specified 12V to 14.4V. Budget time for tuning; eight channels of unconfigured processing is worse than none.

Specifications

• Type: 8-Channel DSP + 4-Channel Amplifier, Class AB
• Power: 23W RMS × 4 @ 4Ω
• Power: 35W RMS × 4 @ 2Ω
• Power: 70W × 4 maximum
• High-level inputs: 4 channels · RCA inputs: 2 · RCA outputs: 8
• Frequency response: 20Hz–20kHz
• THD: <0.05% · S/N: >100dB
• Equalizer: 31 bands
• Crossover: Butterworth, Bessel, Linkwitz-Riley · 6–48 dB/oct
• I/O mixing matrix · PC and app tuning
• Bluetooth streaming: optional external module
• Inputs: Aux, BT, high level, player, OTG
• Input impedance: 20 kΩ (low), 22Ω (high)
• Supply voltage: 12V–14.4V

HF Audio Perspective

The choice between this and the HB 46 II 4A is about how many channels the system needs processed, not how much power it needs.

Both amplify four channels identically. If the system is a two-way front stage plus a subwoofer, six processed channels covers it and the HB 46 II 4A also brings Bluetooth in the box. If the plan is a three-way front stage with bass — eight distinct filtered signals — then eight channels is the requirement and this is the unit. Count the drivers first; the answer follows directly.