Electro‑Harmonix produce some of the most interesting pedals around, but in the studio plenty of us tend to gravitate towards plug‑ins, since they enable you to refine the effects after recording. If you record through a pedal, the effects are effectively ‘burnt’ into the recording, so if you want the ability to tweak later you need to take a clean feed and use a re‑amp‑style setup to match the levels and impedance of your pedal and your audio interface. Wouldn’t it be great if there was an easier way to apply pedals after recording? That’s what the EHX Effects Interface is designed to do.
It comprises both the hardware itself and the EHX FXI software, which you use as a DAW plug‑in; the hardware connects to your computer over USB‑C. Built into a robust metal case, the Effects Interface has rear‑panel jack sockets for left and right I/O, plus a headphone output. The inputs are around 2MΩ impedance, so are suitable for connection to pedals or directly to guitar pickups, while the specified output impedance is 330Ω. Separate faders handle the left and right input and output levels, and a small rotary control adjusts the headphone level. Level meters in the centre monitor the left and right input, and a bypass footswitch takes the external effects loop out of circuit.
The first two modes allow you to insert your pedals into your DAW, or your DAW into a pedal chain...
There are three operational modes: Hardware Plug‑in, Pedalboard and Audio Interface. Once the plug‑in is running, you use the three‑bar menu to select Device/Audio, then choose the required routing option. And those first two modes allow you either to insert your pedals into your DAW, or your DAW into a pedal chain.
The Effects Interface supports mono or stereo pedals, and both instrument‑ and line‑level devices.
Hardware Plug‑in mode routes signals from your DAW through a mono or stereo pedal and then back to the DAW, so the pedal processes the signal in much the same way as a software plug‑in, though obviously a pedal can only be used on one track or bus at once. The audio routing can be set to stereo, left mono or right mono, so two separate mono pedals can be used, each with its own instance of the plug‑in, one set for left mono, the other for right mono. I only had one Effects Interface to test, but I gather that software can detect and manage multiple units, should you wish to add more.
The USB LED indicator in the plug‑in turns green to confirm that audio is flowing through the connected pedal, and adjustments to the physical faders on the hardware are reflected in the virtual fader positions. A wet/dry Mix control is available on the plug‑in, so external pedals such as reverb or delay can be left set to 100 percent wet if required. These routing options can also be used to send a recorded guitar part to an external amplifier for re‑amping. Note, if working in Logic Pro as I do, that the EHX plug‑in will be bypassed if Low Latency mode is activated, so in some situations it may be prudent to save using the EHX plug‑in until mixing.
Pedalboard mode does the opposite: it allows you to insert DAW plug‑ins into a hardware effects chain. First, insert the EHX pedal in your hardware chain. Then select Pedalboard mode in one plug‑in instance in your DAW, set that to ‘In’ to receive the instrument, and use a second instance set to Pedalboard Out for the return.
In Audio Interface mode, the Effects Interface operates as a conventional class‑compliant 2‑in/2‑out USB audio interface, with a Direct Monitor option activated from a front‑panel button. Unlike most interfaces, it operates with line or instrument signals, though note that since its gain staging is optimised for pedals, the maximum input level available is +7dBu.
The plug‑in allows multiple Effects Interfaces to be used in your DAW, alongside your main audio interface.There’s also a Control mode that allows the DAW to control the parameters (Gains and Bypass) of the Effects Interface without routing DAW audio to it, and that can be useful when the pedal is being use in standalone mode. If it’s not connected to a DAW, MIDI control of the Interface parameters is available over USB‑C.
Because there’s A‑D and D‑A conversion involved, I’m sure you’ll want me to discuss the latency. The associated plug‑in has a calibration page, where you can change the buffer setting, and there’s automatic latency compensation for the inherent round‑trip delay. In a Logic project running at 48kHz, with the Block Size in the plug‑in set to be the same as in the DAW, the system added latency of around 340 samples. The automatic calibration gets very close, but because it adjusts in whole‑sample increments the alignment isn’t quite perfect: there’s just the slightest hint of comb filtering on some sounds when tested with a 50 percent wet/dry signal, and a simple ‘loopback’ cable instead of an external pedal. So I’d suggest where possible setting the Mix control in the plug‑in to 100 percent wet, and using the connected pedal’s own mix control, for the cleanest‑sounding results.
Subjective playing tests with my usual 128‑sample DAW buffer setting confirmed that the Effects Interface didn’t compromise the live playing feel. Dropping the Block Size to 32 samples didn’t affect stability on my Mac M1 Mini either. That lowered the added latency to 155 samples, and reduced that sense of comb filtering.
The Effects Interface is a practical solution, very neatly executed.
In conclusion, the EHX Effects Interface makes using external hardware effects within a DAW project quick and easy. While you could do something similar using a multi‑I/O audio interface, finding the right cables and sorting out the routing, gain and impedance can often feel a hassle, interrupting your creative flow or leading you to choose a more convenient plug‑in, rather than the sound you actually want. Having a wet/dry control and level adjustment within the EHX FXI plug‑in keeps all the action on‑screen where it belongs, and it’s very liberating to add effects from your favourite pedals after recording, rather than being committed to them during the recording process. In short, the Effects Interface is a practical solution, very neatly executed.