GNR1 Digital Audio Noise Filter

I. Introduction

The Xiegu GNR1 is a digital audio noise filter and processing device. It integrates digital noise reduction and digital filtering capabilities, making it suitable for external audio processing in wireless receiving equipment such as radio transceivers, receivers, and radios. Its primary functions include reducing background noise, improving the signal-to-noise ratio (SNR), and enhancing signal identifiability. The GNR1 supports connection to an external passive speaker, offering 3W audio output power. It allows for independent adjustment of input and output sound volumes, selection of high/low input impedance, and provides multiple audio output ports (3.5mm stereo output, RCA output). It also features a headphone output with automatic switching between headphone and speaker output.

II. Basic Indicators

• Digital denoiser SNR upgrade degree: More than 22dB
• Digital filter frequency response range: L-CUT adjustment range: 5Hz-1280Hz
• Digital filter frequency response range: H-CUT adjustment range: 500Hz-5615Hz
• Headphone driving power: 100mW@Max
• Headphone output impedance: 16~64Ω
• Input impedance range: Low impedance of 16Ω, high impedance of 10kΩ
• Speaker output power: ≥3W (8Ω, THD≤0.2%)
• Speaker output impedance: 4~16Ω
• Operating voltage: DC12V ± 15%
• Volume: 159*44*143mm

III. Operating Instruction

3.1 Description of Panel

Front Panel:

The front panel features the following controls and indicators:

• Power indicator: Indicates power status.
• CLIP indicator: Lights up when the input audio signal is overloaded.
• NR adjustment knob: Controls the Noise Reduction (NR) function and its degree (200 levels).
• L-CUT adjustment knob: Adjusts the low-cut filter frequency.
• H-CUT adjustment knob: Adjusts the high-cut filter frequency.
• INPUT knob: Adjusts the input sound volume.
• Power switch: Turns the device on/off.
• Headphone interface: 3.5mm jack for headphone output.
• OUTPUT knob: Adjusts the output sound volume for speakers and headphones.

Rear Panel:

The rear panel includes:

• RCA output interface: For connecting to speakers or other audio devices.
• 3.5mm stereo output interface: Another option for audio output.
• SP (Speaker) connector: For connecting an external passive speaker.
• LINE IN connector: For audio input.
• 12V DC input: For connecting the power adapter.
• Input impedance selection switch: Allows selection between high (HI) and low (LO) input impedance.
• Input interface: 3.5mm stereo jack for audio input.
• DC power input: For connecting the power adapter.

3.2.1 Wiring

The audio input is a mono channel via a 3.5mm stereo jack, where two internal tracks are utilized. Do not use a mono channel jack for input, as this may cause a short circuit and prevent sound from reaching the device.

The audio output is also mono channel, provided via two jacks: an RCA jack and a 3.5mm stereo jack. This stereo interface connects two channels within the device. Avoid using a mono channel jack for output to prevent short circuits and loss of sound.

The device operates on DC 12V ± 15%. It can be powered directly using a 13.8V power source commonly found in radio equipment.

Caution: Do not use the device with voltages exceeding the specified range. Do not connect to 220VAC mains power directly.

3.2.2 Selection of Input Impedance

Select the appropriate input impedance level (high or low) for the GNR1 based on the audio output impedance of the connected device. Improper selection may result in reduced output sound volume.

3.2.3 Adjustment of Input Sound Volume

Adjust the input sound volume to achieve a proper output level and distortionless sound quality, in conjunction with the output volume control. If the input audio amplitude is too high, causing overload, the CLIP indicator will illuminate. In such cases, reduce the input sound volume.

3.2.4 Adjustment of Output Sound Volume

The output sound volume knob controls the level for both the speaker and headphone outputs. Adjust to a suitable volume without distortion. For headphone monitoring, it is recommended to turn the knob to the lowest volume setting before inserting headphones to prevent hearing damage from sudden loud sounds.

Note: Upon inserting headphones, the speaker output is automatically muted.

3.2.5 NR Noise Reduction Adjustment

This knob controls the NR (Noise Reduction) function. It offers 200 levels of noise reduction. Turning the knob fully left disables NR. Turning it to the right activates NR and increases the noise reduction level.

Note: NR may cause a slight loss in volume. Adjust the noise reduction degree to achieve a comfortable listening experience.

3.2.6 Adjustment of the Digital Filter

The digital filter is adjusted using the L and R knobs, corresponding to L-CUT (low cut) and H-CUT (high cut) adjustments. Turning the L knob fully left deactivates the L-CUT filter. Turning the H knob fully right deactivates the H-CUT filter.

Schematic Diagram of Filter Composition

The filter comprises L-CUT and H-CUT components that work together to form an effective filter bandwidth.

L-CUT: Controls the low boundary frequency, effectively cutting off low-frequency components.

H-CUT: Controls the high boundary frequency, effectively cutting off high-frequency components.

For daily use, adjust these filters according to personal listening preferences to achieve the best listening effect.

*Note: If the actual bandwidth of the filter is less than the useful bandwidth of the signal, performance may be affected.

Contact Information

Service/After-sales email:

• customer@cqxiegu.com
• tech-supp@cqxiegu.com

Tel: 0769-86346464

Address: 5th Floor, Building C, Futai Hi-Tech Park, No.8 Qingfeng South Road, Keyuancheng, Tangxia Town, Dongguan City, Guangdong Province

Website: www.cqxiegu.com