Since the N-Audio amp cabinet switching system assortment is expanding, I decided to write this article containing tips for using FX-Loop section units in your guitar rig. Currently, there is only an FX-Loop unit available for the Two Amps To Cabinet switcher, but soon there will also be for the 4X4 and 8X7 amp cabinet switchers.
The first power-up
When you start wiring your entire rig, including the FX-Loop extension, my advice to you is to begin by wiring and powering your rig without the FX-Loop. Once everything is functioning correctly up to this point, proceed with the cables for the FX-Loop extension. This approach will make it easier to identify any mistakes.
Potential Ground Issues
Typically, FX-Loop effects sit on the pedalboard next to you. They are connected with two cables to the switching system located at the back near the amplifiers. The ground path starts from the mains outlet, followed by the amplifier. It goes through the FX-Loop, and back to the amplifier. Then to the pedalboard with all the effects, and finally ends with the guitar. This creates a lengthy ground path, increasing the likelihood of ground loops.
Use an Isolated Power Supply
The concept is to isolate the ground of the FX-Loop effects from the ground of the effects connected to the amplifier’s input. Avoid using daisy chain cables to power your overdrive and delay connected to the FX-Loop, as this will create ground loops! Use an isolated power supply like the EBS Runsten or Strymon Zuma, where all outputs are isolated one each other. Such universal stompbox power supplies offer the best solution. Alternatively, you can use two non-isolated power supplies: one for the effects between the guitar and the amplifier, and the other for the FX-Loop effects. However, for optimal performance, use a universal power supply with completely isolated outputs.
Avoid Touching the Jacks
I understand that space for effects on the pedalboard is often limited. Organizing effects in various positions, like playing Tetris, is a common feature among guitarists’ pedalboards. However, it’s essential to prevent grounding issues via the effects jacks for both the effects connected between the guitar and the amplifier and the effects in the FX-Loop. My advice is to try to keep the input effects jacks away from the FX-Loop effects jacks without allowing them to touch each other.
As mentioned in this post, avoid touching the jacks of the amp cabinet switcher. This rule applies here as well. Use only straight jacks connected to the FX-Loop external unit. Right-angled jacks can inadvertently touch each other, connecting the grounds of the amplifiers and creating ground loops.
All N-audio amp cabinet switchers and FX-loop units are designed in a manner where internal relays completely disconnect unused amplifiers including their grounds. This prevents any interaction via ground between amps. By following these guidelines, I assure you that the noise from your guitar rig will remain unchanged. The image below shows the ground loop between the amplifiers when two jacks are touching one each other. Avoid this situation!
The image below displays the individual grouns in the Two Amps To Cabinet FX-Loop section. It is important to know that shorting these grounds from neighboring jacks can generate ground loop issues.
Matching FX-Loop Send Levels from the Amplifiers
When using FX-Loop effects, the signal path is the amplifier preamp section, followed by the FX send-return loop, the master volume, and the power amp. It is important to match the levels going out from your amplifier’s sends to the FX-Loop. You can do that by using long-tail delays. When switching the amplifiers, the remained tails from the previous amplifiers have to be at the same level as the current selected amplifier. Tweak your amplifier’s knob until the sound from the FX-Loop effects has similar levels.
Summary
I hope this topic will help you when wiring up your guitar rig. Mostly when using amp cabinet switchers that allow you to switch FX-loop effects. If you have any questions or concerns regarding FX-Loop effects and amp cabinet switchers in your setup, please don’t hesitate to reach out for assistance.
Niki Hristov