Amplitudes: The Mesa Boogie Blog
Switch-Track ABY: The Legendary Tones of Multi-Amp Rigs
Dual and Multi-Amp setups can deliver some of the THE most stunning and powerful Tone you’ll ever hear. There’s a reason the biggest guitar heroes on the planet run these kinds of setups. Once you stand in front of a rig like this - or better yet, play through one, you’ll understand! Multi-amp rigs also provide unique onstage dynamics when switching between one amp to the other, and for big impact moments, especially BOTH. With some space and distance between them, the WIDTH of the sound when both amps are selected is like a warm blank – or a brick wall – depending on your preferred style of music. Whether it’s two combos or two full stacks, the bottom line is… Dual Amp and Multi-amp rigs are well worth the setup, especially when you have the right tools to do it right.
Solving Ground Loop, Phase and Signal Splitting problems:
If you’ve ever tried to hook up a dual-amp rig with an inexpensive AB pedal, the odds are high that you ended up with some major buzzing or humming noise on either or both amps, most likely caused by a solvable ground loop. The Switch-Track feature set, components, build quality and functionality make it one of the most complete and professional ABY pedals you can get. The Switch-Track is not your average, everyday A/B/Y pedal and achieving great sounding, noise and problem-free multi-amp rigs requires only a few considerations to operate optimally:
- Ground Isolation between A & B outputs
- Buffering to insure optimal signal strength (particularly when BOTH amps are chosen)
- Phase Correction allowing you to flip the phase of an amp or channel to match the phase of a second amp.
Whenever your instrument signal is ‘split’ and connected to two or more amps at the same time, the possibility for ground loop noise begins. Audio transformers are utilized inside the Switch-Track to electrically lift or isolate the ground connection between one or two amps (in a three amp setup) and the pedal. The instrument signal continues to all the amp inputs, but the multiple ground connections between the amp(s) and the pedal are now isolated, breaking the ground loop. With no physical ground connection between multiple amps and the pedal, there’s absolutely no potential for ground loop noise. The general rule is that one amp should always NOT be lifted or isolated, and the second or third amp(s) etc. should ALWAYS be lifted or isolated. To clarify, one amp MUST always provide an earth (safety) ground reference to the guitar and any effects.
Dual Ground Isolation is an industry-first for a pedalboard ABY device and the Switch-Track’s Dual-Iso offers two key advantages over Single Isolation devices. Ground Lift switching is available for both A & B Outputs – Out A’s Lift is external and Out B’s Lift is internal and is default lifted. This creates the potential for using the always-on and buffered Tuner Output for a third amplifier while providing all the necessary options for ground isolation available in a three-amp rig.
With BOTH Outputs ground-isolated, the likelihood of ground loops throughout the rest of your rig connections (past the amp inputs) is dramatically reduced!
When running multiple amplifiers and/or channels, the output phase may be different from one amp or channel to the next. When running both amps together on the BOTH (Y) selection, if the output phase is flipped 180 degrees between each amp, the tone will sound hollow and weak… surprisingly more weak than when just one amp is on by itself.
The output phase of each amplifier or even different channels within the same amplifier is determined by a number of basic design decisions that may vary. For example, a clean sound in a tube amplifier might utilize four preamp tube stages to generate it’s final output, while a distortion channel in the same amp uses five preamp tube stages. In a nutshell, each stage flips the phase 180 degrees. If the two sounds were played together (on two separate amps), the channel with four preamp stages would have a different output phase from the channel with five preamp.
The phase correction feature of the Switch-Track allows you to address phase correction in a few different ways. If you’re using two amps with one channel each and you find the phase is flipped, just select the phase button on the Switch-Track and both amps will now be in phase.
The Switch-Track also allows you to store/recall a phase selection to each MIDI preset/program, regardless of the position of the physical Phase Switch. Once stored in MIDI memory, the Switch-Track recalls your phase selection when a preset requires a phase change. This advanced functionality is just one of the unique and innovative features that sets the Switch-Track apart from all other ABY devices.
Signal Splitting & the Tuner Output:
The final concept that affects multi-amp tone and quality is signal splitting and buffering. When using both amps at the same time, your signal must be ‘split’ to be sent to both amps.
If this signal isn’t addressed when split, what eventually drives either or both amps is a reduced quality of signal at one of the most important points in the chain. The Switch-Track utilizes top notch, transparent buffering circuitry to ensure that the signal strength and detail is fundamentally maintained once split. Where most ABY devices either don’t offer buffering at all or only buffer one side of your signal, the Dual Buffering of the Switch-Track essentially matches your A and B outputs so that optimal signal gets to all inputs regardless of your ABY selection. A side benefit of the buffered Outputs is that they’re set up for Tip-Ring-Sleeve balanced connectivity for enhanced RF interference/noise immunity as well as maintaining signal strength and Tone on longer cable runs.
The Tuner Output is also buffered with the same design as the A & B Outputs, providing another matched output for even more applications. While this might seem like overkill, it actually allows the Tuner Output to be used in a three-amp setup (often used in a stereo wet/dry rigs) with all the same advantages described above. Used as an actual Tuner Out, the buffering maintains the signal strength of the signal to your tuner, especially on longer runs of cabling.
Pedalboard Tip of the Day:
One last (and important) tip for pedal board builders with an ABY… Make sure to locate your pedalboard power supplies, wall warts or power strips as far away from your Switch-Track or any audio isolated switching devices. Isolation transformers of a good ABY may pick up field noise or buzz from any of the above that ground lifting won’t solve.
Ready to Rock?
If you own more than one amp but have never tried a Multi-Amp set up… what are you waiting for? If you’ve been thinking about an ABY, look no further – you’ve just found the best. For touring techs and rig builders, tone-tweaking enthusiasts, and anyone looking to explore the wonders of blending multiple amps and effects, the Switch-Track is a pinnacle piece of gear for connecting, optimizing and enjoying multiple amps and eliminating the problems often experienced with these kinds of setups. The SwitchTrack A/B/Y combines optimized signal and buffering with the complete feature set for trouble-free, multi-amp rig building of any size. If you have any questions about the Switch-Track or any other Mesa products, feel free to contact us via phone, email or social media and we look forward to helping you achieve great tones and great rigs! Thanks for watching.