BlackSheep Electronics 8 Ohm, -20dB, 25W Power Attenuator

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This Black Sheep Electronics 25W -20dB, 8 Ohm power attenuator is designed to sit between the output of a tube amplifier and the input of the cabinet to allow the amplifier to be cranked up, while maintaining a volume consistent with home use.

It can handle input power up to 25 Watts. This is in the range of small tube amp heads that are typically in the 15-25 W range.

-20dB is about right to recover full use of the master volume control at home, whereby it is quiet to the left, moderate at 12 O'clock and loud to the right.
 
The attenuator was designed to to be fully passive and have a flat frequency response over the audio band, while presenting the same speaker impedance to the amplifier over the audio frequency band, ensuring that while the volume is reduced, the tone of the amplifier isn't altered.

The fixed attenuation allows for the flat frequency response design and a lower cost product. You don't need a knob on your attenuator. There are already plenty of knobs on your amplifier.

It is available in 4, 8 and 16 Ohm variants. This is the 8 Ohm model. The impedance is given on the back of the amp and the cabinet. When they differ (sometimes the cabinet is higher impedance) in order to achieve an unaltered tone, the attenuator impedance should match the impedance of the cabinet rather than the amp.

Specifications

• Circuit type: Passive resistive power attenuator for 8 Ohm impedance loads over audio frequencies
  
• Connectors: Input and output jacks. 1/4" / 6.35mm.
  
• Attenuation: -20dB
  
• Maximum continuous input power: 25 Watts
  
• Input impedance: 8 Ohms
  
• Output: To 8 Ohm load at a maximum of 0.25 Watts
  
• Dimensions: 116mm x 60mm x 35mm (with feet). 116mm x 60mm x 30mm (without feet)
  
• Or 4.57" x 2.36" x 1.4" (with feet). 4.57" x 2.36" x 1.18" (without feet)
  
• Unboxed Weight: 185g / 6.5oz
  
• UPC: 857001006001