This is a professional single-channel passive impedance converter (Direct Box) designed for live performances, recording studios, and broadcast applications. The unit employs high-quality audio transformers to convert high-impedance unbalanced inputs to low-impedance balanced outputs, supporting long-distance cable transmission (>100 meters) without distortion while effectively eliminating ground loop noise, hum, and EMI/RFI interference. Its passive design requires no external power supply, offering plug-and-play functionality for connecting high-impedance sources like guitars, basses, and keyboards to professional mixing consoles or PA systems. The unit delivers an exceptional balance of audio fidelity and durability, ensuring natural tonal reproduction and reliable performance.
| Category | Parameter Item | Parameter Description |
| Audio Performance | Number of Channels | 1 (Mono) |
| Frequency Response | 20 Hz～20 kHz (±1 dB) | |
| Total Harmonic Distortion (THD) | < 0.01% (1 kHz, 0 dBu input) | |
| Signal-to-Noise Ratio (SNR) | > 100 dB (A-weighted) | |
| Maximum Input Level | +20 dBu | |
| Maximum Output Level | 0 dBu (balanced output) | |
| Impedance Ratio (Input/Output) | 133:1 (high-impedance input to low-impedance output) | |
| Phase Shift | < 5° (full frequency range) | |
| Dynamic Range | > 120 dB | |
| Isolation and Noise Suppression | Transformer Type | Jensen JT-DB-E Class 10:1 audio transformer (nickel core, Faraday shielded) |
| Isolation Voltage | > 1 kV (input/output) | |
| Ground Loop Noise Suppression | > 60 dB (50/60 Hz); > 40 dB EMI/RFI | |
| Maximum Transmission Distance | > 100 m (balanced XLR cable, no noticeable attenuation) | |
| Ground Lift | Independent switch to eliminate ground loop hum | |
| Interfaces and Connections | Input Connectors | 1 x 1/4″ TS female jack (high impedance, unbalanced) |
| Output Connectors | 1 x XLR male connector (balanced, low impedance, Pin 2 hot) | |
| Thru Output | 1 x 1/4″ TS female jack (parallel output) | |
| Compatible Sources | For high-impedance devices like guitars, basses, keyboards, synthesizers, etc. | |
| Physical and Environmental | Dimensions (L x W x H) | 70 mm x 36 mm x 100 mm |
| Weight | 0.45 kg | |
| Enclosure Material | Heavy-duty 16-gauge steel enclosure, powder-coated | |
| Operating Temperature | -10°C～60°C | |
| Storage Temperature | -40°C～85°C | |
| Humidity | 0%～95% (non-condensing) | |
| Power and Safety | Power Requirements | None (fully passive design) |
| Safety Features | Short-circuit protection; phantom power safe (no internal circuitry) |
400-900-2726
9th Floor, 1B, Shangzhi Technology Park, Guangming District, Shenzhen City, Guangdong Province, China
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