1. Introduction
The Audio DSP DNR is a compact and powerful digital signal processing (DSP) device designed to significantly improve the audio quality from radio receivers, especially shortwave radios. It effectively reduces unwanted noise and applies digital filtering to enhance signal clarity, making communication clearer and more enjoyable. This device is ideal for integrating with older radio stations that lack built-in noise reduction capabilities.
2. Package Contents
Please check the package for the following items:
- 1 x Audio DSP DNR Host Unit
- 1 x 3.5mm Audio Cable
- 1 x USB Type-C Data Cable (for power supply)
- 1 x Set of Machine Corner Pads
3. Device Layout and Controls
Familiarize yourself with the various controls and indicators on your Audio DSP DNR unit:
- ON/OFF Button: Powers the device on or off.
- PWR Port: 5V Micro USB power supply input.
- IN Port: 3.5mm audio signal input. Connect your radio receiver's audio output here.
- OUT Port: 3.5mm audio output. Connect to an external speaker or power amplifier.
- Project Selection Buttons (▼ ▲): Used to navigate and select between DNR (Digital Noise Reduction) and FLT (Digital Filter) settings.
- Level Adjustment Buttons (◀ ▶): Adjust the level or grade of the selected DNR or FLT setting.
- Volume Adjustment Knob (+ VOL -): Controls the output volume.
- Display Screen: Shows current settings, audio spectrum, and other indicators.
- Audio Spectrum Display: Visual representation of the incoming audio signal.
- Built-in Speaker: Provides direct audio output from the unit.
- 'OL' Indicator: Displays 'OL' on the screen if the input signal amplitude is too large, indicating potential overload.
4. Setup Instructions
- Power Connection: Connect the provided USB Type-C data cable to the PWR port on the Audio DSP DNR unit and to a 5V USB power source (e.g., a USB wall adapter, computer USB port).
- Audio Input: Use the provided 3.5mm audio cable to connect the audio output of your radio receiver to the 'IN' port on the Audio DSP DNR unit.
- Audio Output: Connect an external speaker or power amplifier to the 'OUT' port using a 3.5mm audio cable. Alternatively, you can use the built-in speaker for direct audio.
- Placement: Attach the machine corner pads to the bottom of the unit for stability and to prevent scratching surfaces.
5. Operating Instructions
- Power On: Press the ON/OFF button to turn on the device. The display screen will illuminate.
- Adjust Volume: Use the '+ VOL -' knob to set your desired output volume.
- Select Function (DNR/FLT):
- Use the '▼' and '▲' buttons to select between 'DNR' (Digital Noise Reduction) and 'FLT' (Digital Filter) modes. The currently selected item will be indicated on the display.
- Adjust DNR (Digital Noise Reduction):
- When 'DNR' is selected, use the '◀' and '▶' buttons to adjust the noise reduction level. There are 10 grades of noise reduction. Experiment to find the optimal level for your audio source.
- Adjust FLT (Digital Filter):
- When 'FLT' is selected, use the '◀' and '▶' buttons to choose from 10 different digital filter levels. These include:
Figure 3: Display showing DNR and FLT settings. - 200Hz Low Pass Filter (LPF)
- 500Hz Low Pass Filter (LPF)
- 700Hz Low Pass Filter (LPF)
- 1kHz Low Pass Filter (LPF)
- 1.8kHz Low Pass Filter (LPF)
- 2kHz Low Pass Filter (LPF)
- 2.4kHz Low Pass Filter (LPF)
- 3.5kHz Low Pass Filter (LPF)
- 6kHz Low Pass Filter (LPF)
- Through (no filter applied)
The filter and noise canceller can be used together freely to achieve the best audio clarity.
- Monitor Audio Spectrum: The display provides a real-time audio spectrum, allowing you to visually monitor the processed signal.
- Power Off: Press the ON/OFF button again to turn off the device when not in use.
6. Maintenance
- Cleaning: Use a soft, dry cloth to clean the device. Avoid using harsh chemicals or abrasive materials.
- Storage: Store the device in a cool, dry place away from direct sunlight and extreme temperatures.
- Handling: Handle the device with care to prevent physical damage.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Device does not power on | No power supply or faulty cable | Ensure USB Type-C cable is securely connected to a 5V power source. Try a different cable or power adapter. |
| No audio output | Incorrect audio connections, volume too low, or external speaker issue | Check 3.5mm audio cable connections to IN/OUT ports. Increase volume using the '+ VOL -' knob. Test with a different external speaker or use the built-in speaker. |
| 'OL' displayed on screen | Input signal amplitude is too large | Reduce the audio output volume from your radio receiver or source device. |
| Noise reduction/filtering is ineffective | DNR/FLT levels not optimally set | Experiment with different DNR grades and FLT frequencies using the adjustment buttons to find the best setting for your specific noise environment. |
8. Specifications
| Feature | Specification |
|---|---|
| Model | DSP noise reducer (Audio DSP DNR) |
| Item Number | AL-282 |
| Power Supply | 5V Micro USB (Type-C input) |
| Audio Input | 3.5mm Jack |
| Audio Output | 3.5mm Jack, Built-in Speaker |
| DNR Levels | 10 grades |
| FLT Levels | 10 levels (200Hz, 500Hz, 700Hz, 1kHz, 1.8kHz, 2kHz, 2.4kHz, 3.5kHz, 6kHz LPF, Through) |
| Dimensions (L x W x H) | 100mm x 70mm x 17mm (3.9in x 2.8in x 0.7in) |
| Approx. Weight (packaged) | 170g |
| DIY Supplies Category | Electrical |
| Origin | Mainland China |
9. User Tips
- Experiment with Settings: The effectiveness of DNR and FLT can vary greatly depending on the type of noise and the audio source. Take time to experiment with different combinations of DNR grades and FLT frequencies to find the optimal settings for your specific listening conditions.
- Optimal Input Level: Avoid overdriving the input. If you see the 'OL' indicator, reduce the input volume from your radio to prevent distortion and ensure proper DSP processing.
- External Speaker Quality: While the device has a built-in speaker, connecting it to a high-quality external speaker or amplifier will provide a much better listening experience and allow you to fully appreciate the improved audio clarity.
10. Warranty and Support
For any questions, technical support, or warranty claims, please contact the seller or manufacturer directly. Keep your purchase receipt as proof of purchase.
