Zapco HB 68 II — 8-Channel Digital Signal Processor

Zapco HB 68 II — 8-Channel Digital Signal Processor

The HB 68 II is an eight-channel digital signal processor with no onboard amplification — the processing section of the HB II line supplied on its own, for systems where amplification is already handled.

Signal-to-noise is better than 100dB with THD under 0.05%, across a 20Hz to 20kHz bandwidth. Supply voltage is 12V to 14.4V.

Six High-Level Inputs

The HB 68 II accepts six channels of high-level speaker input plus two RCA inputs, with eight channels of RCA output.

Six high-level channels is more than the amplified models in the line offer, and it is the reason to choose a processor-only unit for factory integration. Modern factory systems split the signal across multiple channels with different equalisation and filtering applied to each. Capturing six of them gives the processor enough of the original signal to reconstruct a full-range source before re-filtering it for your drivers.

Input impedance is 20 kilohms on low level and 4.7 ohms on high level.

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 crossover slope range covers gentle first-order filters through to steep 48 dB per octave separation, so the filter can suit the drivers and their mounting positions rather than the reverse.

The I/O mixing matrix routes any input to any output. With six high-level inputs arriving from a factory system that filtered them for its own speaker layout, that routing flexibility is what makes the signal usable for a different set of drivers.

Sources

Input selection covers Aux, Bluetooth, high level, the app music player, and OTG. Bluetooth streaming is available through an optional external module, and the app player means the unit can act as a source as well as a processor.

System Application

Eight processed channels feeding external amplifiers — a three-way active front stage plus subwoofer, or a two-way front with rear fill and bass, with amplification chosen independently for each section.

This is the configuration for a system where amplifier selection is a separate decision: existing amplifiers being retained, or specific amplifiers chosen to match particular drivers.

Installation Considerations

Note the high-level input impedance of 4.7 ohms — lower than the 22 ohms specified on the amplified models in the line. Some factory amplifiers detect speaker load, and a low input impedance presents a load closer to a real speaker, which can matter for systems that fault when they see an open circuit.

Plan the amplifier gains alongside the processor's output levels. With eight channels feeding external amplification, gain structure across the whole chain determines the system's noise floor more than any single component does.

Budget real time for tuning. A processor delivers nothing until it is configured.

Specifications

• Type: 8-Channel DSP (no onboard amplification)
• High-level inputs: 6 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
• Inputs: Aux, BT, high level, player, OTG
• Bluetooth streaming: optional external module
• Input impedance: 20 kΩ (low), 4.7Ω (high)
• Supply voltage: 12V–14.4V

HF Audio Perspective

A processor without amplification is the right choice more often than the all-in-one units suggest.

Amplifier requirements vary enormously across a system — a tweeter wants a few watts of clean power, a subwoofer wants hundreds. Combining processing and amplification in one chassis forces a compromise on that spread. Separating them means each driver gets amplification sized for it, and the processor is chosen purely on its channel count and tuning capability.

That costs an extra chassis and another set of interconnects. What it buys is the freedom to match every part of the system to its job — which is the whole argument for designing a system rather than assembling one.