The inside story of Walrus Audio’s Slö Multi Texture Reverb, one of 2019’s must-try effects

The brand-new Walrus Audio Slö continues the US boutique builder’s reputation for creating interesting esoteric effects. And as our review attests, it’s everything that lovers of ambient soundscapes could want in a reverb stompbox.

Keen to find out the thinking behind the Slö’s creation, we chatted to the pedal’s designer, Jason Stulce, to find out just what makes this clever little box stand apart from other reverb pedals on the market…

Walrus has had lots of success with modulation, what made you decide that you wanted to make a modulated reverb?

“I love modulation! The inspirational texture it can bring when creating parts and for making simple lines or chords more interesting is really fun. I’ve always been intrigued with LFOs and wave shapes, and knew I wanted to flesh out some ideas with the LFO on the Slö that I had not seen before.”

The name is also pretty interesting. Can you tell us the thinking behind calling it the Slö?

“When we started to really think about this reverb and how it was conceptually shaping up in our heads, we knew it was going to lean toward a more atmospheric, soundscape, texture-type reverb.

“We kept going back to the concept of sleep. When we started researching words associated with sleep we ran across the Swedish word for ‘drowsy’ and we almost instantly knew we had it. The Walrus Audio Slö Reverb.”

Can you talk us through the design process for the pedal?

“I drew a lot from the things we learned when creating the Fathom reverb. That helped get past some hurdles, but there were plenty of new ones with the Slö. The biggest hurdle was figuring out how to have complex LFO wave shapes modulate the reverb with the limitations of the FV-1 DSP chip.

“Then there was the actual designing of the reverb sounds themselves. That involves determining what the X knob should do in each algorithm, as well as tuning the filter range and resonance to work well with the sound of each reverb. It is quite a process, but I attack one piece at a time – and from time to time, ‘zoom out’ and consider how each piece fits with the pedal as a whole. That is an important aspect of creating a cohesive pedal that incorporates multiple sounds.”

There are lots of different ambient reverbs out there, what makes the Slö different?
“I think one of the big differences is the modulation. It is implemented in a way I haven’t seen before and it creates this interesting pitch-bending and chorusing effect that is really fun to play with.”

What sort of sounds can people create with the Slö?

“It really lends itself to creating dense warm inviting soundscapes and textures behind what you are playing. It’s also a great tool for creating pad-type sounds from your guitar. You can use the sustain switch to drag out notes and landings of phrases and the depth knob lets you bring in just the right amount of modulation to accent what you’re playing.

“Hint! The modulation shows up more as your dry signal dies off, so don’t be afraid to let the pedal breathe a bit!”

It’s also got three interestingly named modes – Dark, Rise and Dream…

“Dark mode was demanded by Colt [Westbrook, Walrus Audio president]! He loves the low octave you can apply to the reverb on the Descent and Fathom, and he really wanted to highlight it on this pedal. It’s great for creating dark, spooky sounds as well as dense 3D-sounding reverbs.

“Rise was my baby. I LOVE reverbs that sneak in behind what you are playing. I tend to play lots of quiet, clean picked parts and I really like how the Rise reverb will stay out of the way when I’m picking a note and fade in a moment later to support the note as it sustains.

“Dream mode was built for pad sounds. I had the idea to make the sustain switch latch in that mode to allow for really long, sustaining reverb decay which you could then play over. Through some software wizardry, I was able to make the sustain switch latch in that mode only and at the same time, lower the dry signal feeding the reverb to allow you to play clean over the sustained pad sound. I probably would have had this design done sooner, had I not been caught up playing over latched pads for a half hour here and there!”

The secondary features give a load of extra sonic potential, too…

“Yeah, they do! We knew we wanted to keep this guy in a smaller footprint and I knew a big focus was going to be the modulation ability. I could have hard-coded the modulation rate and wave shape to be set in stone for each of the three modes, but I thought, ‘That’s lame!’

“So I decided I would make those two parameters user accessible, but since they are less common than say mix or filter, I would make them secondary functions accessible by holding down the bypass switch when the pedal is on.

“The wave shape impacts how the modulation is realised. Do you want it to pitch up and down evenly? Just raise the pitch, like warp does? Or maybe asymmetrically and logarithmically, only pitch-down, like the Sink mode? The rate control changes how fast the LFO modulates the reverb decay. Go from super-slow broken record-type speed, to crazy fast vibrato effects.”

There are obviously loads of interesting pedals in the Walrus range, have you got a favourite to pair the Slö with?

“Well, the easy answer is the ARP-87. Delay and reverb go together like peanut butter and jelly (must be grape jelly). Another pedal I’ve really enjoyed pairing with it has been our 385 overdrive.

“It’s so dynamic and touch-sensitive, and when you combine it with the Slö, it makes for a fun new expressive pairing that lets you dig in and back off to create all kinds of tones, from gritty to clean.”

Read our review of the Walrus Audio Slö here.