The BUGERA 333XL INFINIUM tube amplifier offers remarkable flexibility, allowing guitarists to achieve full valve saturation even at lower volume levels. Thanks to the Infinium Valve Life Multiplier - an intelligent auto-bias system - you can safely reduce the output power while maintaining the amp’s performance, tonal integrity, and signature tube character.
Benefits of Reducing Output Power
Lowering the output power not only helps you control volume more easily but also brings several important advantages for guitar players:
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Maintain full tube saturation and tone at lower volume levels
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Ideal for home practice or recording in smaller spaces
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Reduce operating temperature and tube wear, extending amp lifespan
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Preserve load safety and output stability
Step 1 - Power Off the Amplifier
Before performing any adjustments, make sure the amplifier is completely powered off and disconnected from the mains to avoid any risk of short circuits or component damage.
Step 2 - Remove Two Power Valves
The 333XL INFINIUM uses four power tubes located on the rear panel.
To cut the output power in half, you may remove either the inner pair or the outer pair of power tubes - but never remove them alternately.
👉 Example:
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If you remove the two inner tubes, the two outer tubes will continue to operate normally.
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If you remove the two outer tubes, the two inner tubes will handle the remaining power.
Thanks to the Infinium auto-bias system, the amplifier automatically adjusts the current balance, ensuring stable operation without manual biasing.
Step 3 - Adjust the Impedance
After removing two power tubes, you must reset the output impedance to maintain a proper load match.
You have two safe options:
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Option 1: If you’re using an 8 Ohm speaker load, set the Impedance Selector to 16 Ohms.
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Option 2: If you prefer to keep an 8 Ohm load, set the selector to 4 Ohms.
Both settings ensure the remaining tubes handle the load correctly, preserving amp performance and protecting internal components.
Results After Reducing Output Power
Once completed, the BUGERA 333XL INFINIUM will operate at half power, allowing you to:
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Achieve authentic tube saturation at lower volume levels
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Retain the signature 333XL tone - powerful, harmonically rich, and naturally compressed
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Play in smaller environments without excessive volume, while still enjoying true tube dynamics
Important Handling Notes
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Always allow the amplifier to cool down completely before removing any power tubes.
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Do not mix tubes of different types or gain ratings when reinstalling.
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Never operate the amplifier without a connected speaker load (cabinet) to prevent output transformer damage.
Conclusion
The output power reduction feature of the BUGERA 333XL INFINIUM provides players with maximum flexibility - from large stage performances to small rehearsal rooms.
Thanks to the Infinium auto-bias technology, removing tubes and adjusting impedance becomes a safe, simple, and effective process, enabling you to enjoy the authentic warmth and saturation of tube tone at any volume level.