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BigShot™ SW2 Using & Applications

The following page describes how to use the BigShot ABY and discusses some of the functions that are built in. To view the complete manual, simply click on the icon at left.


Following the block diagram from left to right, you will note the instrument input and the tuner out. The tuner is always on allowing you to monitor the instrument and make adjustments as needed. Next is a toggle switch that sends the signal to either OUT-A at the bottom or OUT-B at the top. These connect to your two amplifiers.

Depressing the TOGGLE switch allows you to toggle between the A or B amps whereby one could be set for rhythm while the other could be set for lead. In either case, the audio signal is 100% true bypass meaning that there is no preamp or buffer in the circuit to get in between your guitar and your amplifier. For the purist, this is bliss. In between there is a 'BOTH' switch that basically combines the two signal paths. Depressing the BOTH would of course activate both amps so that both are on at the same time. OUT-B is also equipped with an isolation transformer and a ground lift switch to help eliminate ground loops, plus a 180º polarity reverse that enables you to phase match the two amps so that both speakers are pushing outwards (in phase) at the same time.

Making Connections

Before making connections, make sure all levels are turned down. This eliminates plug-in transients that could damage speakers or reduce their lifespan. Check to make sure all three of the switches on the BigShot ABY are in the down (off) position. This will take the transformer out of the signal path, connect the ground to both amps and assume that both amps are in phase.

Connect your guitar to the input and OUT-A to amp-A and OUT-b to amp-B. Turn up the volume on amp-A to a low listening level. Start playing guitar and listen. If no sound, toggle the AB switch. If still no sound, connect your guitar directly to your amp to test that it is working correctly. Then, check your cables one by one to see if there is a fault. 99% of the time, a bad cable is the culprit! Now that you have signal working on amp-A, turn up amp-B, depress the AB toggle footswitch and listen. You should now hear your guitar.

Using two amps at once

When using two amps at the same time, you will often find that noise can find its way into your setup. This is usually attributed to what is commonly known as a 'ground loop'. This is caused by differing reference voltages on the twoamps and noise traveling freely across the electrical ground and the audio ground. The buzz and hum can often be so loud that it makes playing impossible.

The BigShot ABY is equipped with two switches to help resolve these problems. The first is a LIFT switch. Pushing this upwards disconnects the ground path going to OUT-B. This can sometimes eliminate the ground loop and noise. If this does not work, the ABY is also equipped with a second switch called ISO. Pushing this up introduces an isolation transformer into the circuit, disconnecting the electrical signal path. Transformers are wonderful devices that allow the audio signal to pass while eliminating hum and buzz caused by ground loops.

But as with all good things, nothing is ever free. When you introduce a transformer into the signal path you will invariably alter the tone. This is because transformers are passive. In many cases, the tone shift can easily be compensated for by adjusting the controls on your amp. Further, if you are buffering the signal with non true-bypass pedals, the buffers will automatically drive the signal and lessen the effect of the transformer.

Playing both amps in phase

A huge benefit to having a transformer in the circuit is that it enables you to reverse the electrical phase or polarity going to the second amplifier. Often, when playing two amps at the same time, you will find that one may be out of phase versus the other. This is most noticeable in the low end where the bass is reduced and the stereo image sounds wider. To fix the problem, simply engage the transformer by pushing it in the up position and the try toggling the 180º switch. Up is polarity reversed.

In more exotic setups where you may have different pedals going to each amp, you may find that these can also reverse the polarity. Toggling the 180º switch makes it easy to compensate.

WARNING - Possibility of electrical shock hazard exists. Please read the warnings in the user manual before attempting to connect amplifiers to this device.