How to Use an Effects Loop As an Attenuator on a Tube Guitar Amp

Use the effects loop to insert resistance between amp and speaker.

The louder you crank your tube amp, the "hotter" the tone. This is because the power tubes work harder to achieve high volumes and, subsequently, they drive the output stage. One drawback of tube amps is that you need to set them loud to optimize the tone, and high volumes aren't always appropriate. However, by using a power attenuator device in the effects loop, you effectively "soak up" some of the power before it reaches the speakers. This way you drive the tubes just as hard but the output volume is more manageable.

Things You'll Need

• Power attenuator
• 2 instrument cables

Instructions

1. Turn off your amplifier and turn the master volume dial to zero. This is to protect your ears in case anything goes wrong when you turn the amplifier back on.

2. Connect an instrument cable to the "Send" jack on the rear of your tube amp. Connect the other end of this cable to the "Input" jack on the power attenuator.

3. Connect a second instrument cable to the "Return." Connect the other end of this jack to the "Output" jack on the power attenuator. The effects loop is a circuit between the preamp stage of the amp and the speaker. By adding this device to the loop, you place it between the amp and the speaker.

4. Turn on the power attenuator. Select a level of volume of compensation. The options vary according to make and model, but you typically have three or four decibel level options. For example, the Gibson Power Stealth power attenuator has a "-16 db," "-12db," "-8db," "-4db" and "-0db" option. The more reduction you apply, the louder you can turn your amplifier.

5. Adjust the ancillary controls on the power attenuator to your preference. These differ from model to model, but typically include "Equalization" and "Level." For example, the Rivera "Rock Crusher" attenuator features a "Bypass" button which saves you from removing and unplugging the device should you opt not to use it.

6. Turn on the amplifier and gradually increase the volume. The power attenuator is a load-resistance device. It applies resistance to the signal as it guitar passes to the output stage of the amplifier. This lets you crank up your amp to get hot tones, without the window-shattering volume. However, you should never assume that the presence of the attenuator will protect your ears. Always turn the volume up gradually. It takes only one clumsy band-mate to step on an instrument cable to break the effects loop circuit and render the power attenuator ineffective.

References

• Amp Tone: Power Attenuator FAQ
• Shred Knowledge: Tube Juice Power Attenuator Review