Logidy originally created the EPSi pedal to allow guitarist's to add a convolution based reverb to their pedalboard. However shortly after their product announcement, the company was inundated with inquiries of using the pedal to run IRs (impulse responses) of guitar cabinets. Within a few weeks, firmware revision C was made available for exactly that purpose (either firmware can be loaded to the unit by the user). This review will be focused solely on this firmware.
So what is an IR anyway? Think of it as an aural snapshot of a environment. The way it's created is by sending a signal (impulse) into a environment (and and environment can be anything from a power amp/speaker cabinet to a cathedral) and then removing the original signal from the results which leaves only the impact of the environment (response). An IR is only linear, meaning it does not capture an compression or distortion. So why would a guitarist care about an IR? Well, using a process called convolution and IR can be a very precise way to recreate reverb and speaker cabinets.
It's somewhat hard to write a review for an IR loader as if the pedal is doing it's job, it sounds exactly like the IRs loaded into it...which is exactly the case with the EPSi. I paired the EPSi with my Digitech GSP1101 to compare the differences between the same IR loaded into the GSP (which truncates the file), with a ZOOM G3, and with various dirt boxes and loaded up IRs from retailers Redwirez and Ownhammer, as well as the famous free Guitar Hacks set and in all cases the pedal performed exactly as expected. In comparison to the GSP, the non-truncated IR in the EPSi exhibited a fuller low end and smoother highs. In come cases the differences were rather drastic while in others less so but in every case I prefered the EPSi to the GSP. Paired with the Zoom G3 there was really no comparison, I didn't encounter any cases where the native cabinets came close to the EPSi. I find the G3's aural response to be a bit thin and slightly fizzy requiring an EQ assigned to one effect slot to smooth things out. The EPSi frees that spot up for another effect. Pairing dirt pedals I got mixed results. In most cases things were certainly usable but in most cases the results weren't as amp like as the pairing with the GSP or G3. I often had to use the EPSi's EQ to tailor the sound a bit. Though I must add that an old modded DS1 I had paired incredibly well with a GuitarHack IR resulting in a sound I'd be totally happy gigging or even recording. By taking a modular approach, the EPSi could be partnered with any number of peramps with fantastic results.
But the EPSi's design also allows some very creative options other than straight up IR loading for those who think outside the box. First off, the EPSi supports IRs up to 1.5 seconds in length. As such, once can load up an IR in a DAW, add a reverb, and create a new IR with reverb which can be loaded up. Since the Logidy is stereo, one can create an IR with different cabs on the left and right sides...or a case in which one side is an IR and the other side nothing in order to split on'e signal running one output to the board and the other to an amp. And remember, an IR can be a representation of any environment...such as an acoustic guitar, a grand piano, etc. There are some incredibly cool options available to those who think outside the box.
The Logidy EPSi really is a game changer in many ways. Not too long ago convolution processing was something which couldn't be done in real time without some significant compromises. At $200, the Logidy EPSi is priced within the reach of nearly every guitarist and is a great way to improve the sound of a budget modeler or add a direct option to your pedal board.
Pros: IR Loading at your feet.
Price: $199.95 USD