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PowerTube™ FAQ

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How does the PowerTube compare to the PowerPre?

One is tube, the other is solid state. Solid state preamps tend to be cleaner yet employ transformers to add color and character. Tube preamps tend to have more natural even and odd harmonic distortion.

What is the required plate voltage for a 12AX7 to run well?

The 12AX7 tube is designed to work from 125 volts to 300 volts. The higher the heater voltage, the more output it will produce and the shorter the lifespan. Engineers balance this depending on task. The PowerTube applies 140 volts to the B+ which in turn feeds the plate.

How does the PowerTube develop 140 volts?

A special circuit called a charge pump takes the 16V supply from the 500 series rack and kicks it up to 140 volts to feed the tube.

I have an API Lunchbox, will the PowerTube work?

Yes. Just make sure you do not exceed the overall power capacity of the power rack as you will drain the available current which of course will reduce the fidelity and dynamic range of the PowerTube.

I do not have a Radial Workhorse. How can I access the instrument input (Omniport)

Sorry. You need a Radial power rack like the Workhorse, Cube or PowerStrip to access the Omniport function.

Will the PowerTube distort like a guitar amp?

No. The intent is to add character and harmonics, not guitar type distortion.

What happens if I change the tube?

The sound will change and you can get more noise. Try it... it is easy and fun!

What is the polarity reverse used for?

This is often used when two or more mic preamps are used at the same time. By moving the mics around the room and changing the polarity of one versus the other, you can create some great sounds. This can also eliminate resonant peaks inside the room.

What makes a Jensen Transformer so special?

They are immaculately made, extremely consistent, low noise, do not distort, have incredible range and are guaranteed for 20 years. Jensen wrote the book on audio transformers. They are wonderful!

If using only one or two PowerTubes, should I concern myself with the current sharing switch?

No. Simply make sure it is set to the normal position.

How would you characterize the instrument input circuit?

The Omniport 1/4" instrument input is optimised for electric bass and guitars with the input impedance dropped down to around 200k to produce a smooth, warm tone. This makes it great for tracking and later Reamping.