1. Introduction and Overview
The Willsenton R8 is a high-fidelity integrated vacuum tube amplifier designed for exceptional audio performance. This amplifier features a pure hand-made construction with scaffolding welding, ensuring meticulous craftsmanship. It incorporates a specially developed square power transformer and two high-quality wideband EI output transformers for superior sound reproduction. The R8 offers versatility with selectable Triode and Ultra-Linear modes, and supports various tube types including KT88, 6550, and EL34, allowing users to customize their audio experience. An external independent BIAS-ADJ current display header facilitates precise bias adjustment. The amplifier also includes an infrared full-featured remote control and a power-on mute delay function for user convenience and component protection.
Figure 1: Front view of the Willsenton R8 Vacuum Tube Amplifier in Silver.
Video 1: Official overview of the Willsenton R8 KT88 Tube Integrated Amplifier, showcasing its design and features.
2. Setup and Connections
2.1 Tube Installation
The Willsenton R8 comes with tubes pre-installed. However, if you need to replace tubes or are setting up for the first time, ensure all tubes are securely seated in their respective sockets. The amplifier uses 6SL7x2, 6SN7x3, and KT88x4 (or EL34/6550) vacuum tubes. An easy-to-install plug-in tube shield is provided for protection.
Figure 2: Close-up view of the vacuum tubes on the Willsenton R8 amplifier.
2.2 Audio Input Connections
Connect your audio sources to the appropriate input terminals on the rear panel. The R8 provides multiple input options:
- CD Input: For connecting a CD player or other line-level source.
- AUX1, AUX2 Inputs: For connecting auxiliary audio devices.
- PRE-IN Input: For connecting an independent preamplifier, utilizing the R8 as a pure power amplifier.
2.3 Speaker Output Connections
Connect your speakers to the output terminals. The R8 supports both 4 ohms and 8 ohms speaker impedances. Ensure correct polarity (+ to + and - to -) for each speaker.
2.4 Tube Selection Switch
The amplifier features an external switch on the rear panel to select between EL34 and KT88 tube types. Ensure the switch is set to match the tubes currently installed in your amplifier for optimal performance and to prevent damage.
Figure 3: Rear panel connections, including input terminals, speaker outputs, and the tube selection switch.
2.5 Power Connection
Connect the power cable to the AC input on the rear panel and then to a suitable power outlet. The amplifier operates on ~120V ± 5% (50Hz).
3. Operating Instructions
3.1 Power On/Off
Turn the power rotary switch to the 'ON' position. The amplifier features a power-on mute delay function (approximately 30 seconds) to protect components during startup. The power indicator light will illuminate.
3.2 Input Selection
Use the 'SELECTOR' button on the front panel or the remote control to cycle through the available audio inputs (CD, AUX1, AUX2, PRE-IN). The corresponding signal input indicator light will show the active input.
3.3 Volume Control
Adjust the 'VOLUME' knob on the front panel or use the remote control to set the desired listening level. The R8 uses a Japanese ALPS high-end motor potentiometer for smooth volume adjustment.
Figure 4: Front panel controls including power, input selector, and volume knob.
3.4 Triode/Ultra-Linear Mode Selection
Press the 'TR/UL' button on the front panel or the remote control to switch between Triode and Ultra-Linear modes. This allows you to experience different sound characteristics based on your preference.
3.5 Headphone Output
Connect your headphones to the 6.35mm headphone output jack on the front panel. The headphone output impedance is suitable for headphones ranging from 30 ohms to 300 ohms.
Figure 5: Side view highlighting the 6.35mm headphone output jack.
3.6 Bias Adjustment
The R8 features an external independent BIAS-ADJ current display header. Refer to the detailed bias adjustment procedure in the full user manual for precise calibration of the power tubes.
4. Maintenance
4.1 Cleaning
Regularly clean the amplifier's exterior with a soft, dry cloth. Avoid using liquid cleaners or solvents, as they may damage the finish or internal components.
4.2 Tube Care and Replacement
Vacuum tubes have a finite lifespan and may require replacement over time. Handle tubes carefully, avoiding direct contact with the glass to prevent oil transfer. When replacing tubes, ensure the amplifier is powered off and unplugged. Always replace tubes with the correct type and ensure they are properly seated.
4.3 Burn-in Period
For optimal sound quality, it is recommended to allow the amplifier a burn-in period of 100-300 hours. The sound will generally stabilize after 100 hours, with peak performance achieved after accumulating over 300 hours of use.
5. Troubleshooting
If you encounter issues with your Willsenton R8 amplifier, refer to the following common troubleshooting steps:
- No Sound: Check all cable connections (input sources, speakers, power). Ensure the amplifier is powered on and the correct input is selected. Verify speaker impedance matches the amplifier's output.
- Distorted Sound: Check for loose tube connections. Ensure the tube selection switch (EL34/KT88) matches the installed tubes. Verify that the input signal is not too strong, causing clipping.
- Hum or Noise: Ensure all cables are properly shielded and connected. Check for ground loop issues. Verify that the amplifier is not placed too close to other electronic devices that may cause interference.
- Pops when switching inputs/modes: A slight pop may occur when changing inputs or switching between Triode/Ultra-Linear modes. This is generally normal for tube amplifiers and not indicative of a fault, unless excessively loud or persistent.
- Remote Control Not Working: Check the remote control batteries. Ensure there are no obstructions between the remote and the amplifier's remote control receiver window.
If the issue persists after attempting these steps, please contact Willsenton customer support for further assistance.
6. Specifications
| Feature | Specification |
|---|---|
| FTC Power Output Rating (KT88 Triode) | 16W + 16W (8ohms, 20HZ-20KHZ, THD 1%) |
| FTC Power Output Rating (KT88 Ultra-Linear) | 30W + 30W (8ohms, 20HZ-20KHZ, THD 1%) |
| Output Power Rating (RMS KT88 Triode) | 23W+23W |
| Output Power Rating (RMS KT88 Ultra-Linear) | 45W+45W |
| Whole Machine Frequency Response | 12Hz-40KHz (± 1.5dB) |
| Harmonic Distortion | 0.2% (1W/1kHz, rated output power less than 5%) |
| Signal to Noise Ratio | 89Db (weighted by A) |
| Input Sensitivity (merged) | 320Mv |
| Input Sensitivity (Power stage) | 700Mv |
| Input Impedance | 100k Ω |
| Input Terminals | CD, AUX1, AUX2, PRE-IN |
| Output Impedance | 4 ohms, 8 ohms |
| Headphone Output Impedance | 30 ohms to 300 ohms |
| Power Supply Voltage | ~120V ± 5% (50Hz) |
| Dimensions (WxDxH) | 400x390x200mm (15.75 x 15.35 x 7.99 inches) |
| Vacuum Tubes Used | 6SL7x2, 6SN7x3, KT88x4 |
| Net Weight | 26kg (57.2 pounds) |
| Power Consumption | 280W |
7. Warranty and Support
For warranty information and technical support, please refer to the documentation included with your Willsenton R8 amplifier or contact Willsenton customer service directly. Keep your purchase receipt as proof of purchase for any warranty claims.
