Radial Stagebug User Guide
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Using The StageBug SB-2 ™ Passive Direct Box

The Radial StageBug SB-2 has been designed to be plug & play easy to use. The following describes how to connect and get the most out of it. Feel free to download the manual by clicking on the icon at left.


The SB-2 Passive is an ultra-compact direct box designed for keyboards, active basses, acoustic guitars and other devices that produce high output levels. What makes the SB-2 particularly useful is that it employs a transformer isolated circuit that does not require any power, produces a warm, pleasing tone and eliminates troublesome buzz and hum caused by ground loops.

A ground loop can sometimes occur when connecting two AC powered devices such as a keyboard and a mixer together. Ground loops can also occur when using a direct box with an electric bass or guitar amplifer. The SB-2 Passive employs a high quality isolation transformer that breaks the ground loop and eliminates noise.

Making Connections

Before making connections, always turn audio levels down or the PA off. This will help eliminate turn-on transients that can damage more sensitive components like tweeters. Because the StageBug SB-2 is 100% passive no battery or external power supply is required.

Connect your instrument to the SB-2 input using a standard ¼” instrument cable. Connect the XLR output from the SB-2 to the PA or recording system using a standard XLR cable. You can now turn on the PA and start testing. Always test at low volumes as this provides a margin of safety should something not be connected properly.

Adding a Stage Amp or Tuner

The SB-2 is equipped with a THRU-put connection that lets you connect your instrument to an on-stage amp or personal monitoring system so that you can create a comfortable listening environment for yourself. This output is fed directly from the instrument and is not affected by the PAD switch. If you like you can also use the THRU output to feed a tuner.

Using the SB-2 in the studio

The StageBug SB-2 also works great in the studio for bass, electric guitar and keys! It converts the hi-z output of your instrument to a balanced lo-Z output to feed the recording interface. The SB-2 applies the proper load on the pickup and produces a smoother, more natural tone than connecting your instrument directly to the recorder. This is particularly important if you plan to do some Reamping at a later date.

To record direct plug the SB-2 output into your favourite microphone preamp, or simply connect to the mic inputs of your mixing console or digital workstation. The StageBug SB-2 sounds great, has plenty of headroom and delivers the most essential features to get the job done.

Using the Auto-Merge Input

The SB-2 is equipped with an auto-merge feature that combines the left and right outputs from a stereo device like a keyboard or MP3 player to produce a mono output at the XLR to feed the PA. This innovative function saves valuable channels at the mixing console while eliminating the need to reprogram audio files or stereo setups before a show. To use the auto-merge, simply connect the left and right outputs from your stereo device to the ¼” INPUT and THRU jacks and the SB-2 will do the rest for you!

Using The PAD To Tame Loud Instruments

Some instruments such as digital pianos or active basses generate extremely high output levels which can cause more sensitive circuits to overload and distort. Although it is unlikely that you will overload the StageBug SB-2, it is equipped with a PAD switch that will reduce the input sensitivity and subsequent signal level going to the audio circuit by 15dB. Should you encounter distortion, simply depress the pad.

Using The Ground Lift

In some instances, you may find that you are experiencing excessive hum or buzz that may not have been present at your last show. This is known as a ground loop and is often caused by the audio ground interacting with the electrical ground. The SB2’s passive circuit is equipped with a transformer that often helps solve the problem. This is augmented with a ground lift switch that disconnects pin-1 on the XLR to lift the audio ground. If you encounter noise, simply push in the LIFT switch.