Walrus Audio ACS1 Review
Our Review Verdict and Summary
The ACS1 sounds exactly like you would expect a powerful tube amp to sound, which is remarkable considering it's entirely digital. And while it's certainly not a "gain monster", it provides some of the best clean tones we've ever heard from a stompbox-form amp modeler. For those bringing their own distortion source and pedalboard, it's a fantastic amp-in-a-box solution.
I can't imagine it's easy to algorithm your way to a faithful tube amp tone in an entirely digital pedal. But the guys at Walrus Audio have, time and again, proven that today's digital guitar pedals are becoming increasingly hard to distinguish from their analog counterparts.
That brings us to the Walrus Audio ACS1, a preamp and amp modeling pedal with an entirely digital circuit.
For this review I tested the ACS1 with a PRS CE 24 electric guitar (my go-to axe), covering both the pedal's headphone out and its mono output to a pair of Mackie Studio monitors.
The tone I got from this setup was astoundingly good, both from the headphones and the Mackie monitors.
I'll walk you through all the details in this Walrus Audio ACS1 review.
Questions can go in the comments section below.
For starters, use this comparison section to see the ACS1 next to a few other similar Walrus audio pedals.
Walrus Audio ACS1
Walrus Audio Slo Multi-Textured Reverb
Walrus Audio ARP-87 Delay
Walrus Audio Mako D1 Delay
Basic Scoring, Pros, and Cons
This is our main rating card for the ACS1, meant to give you a quicker look at how we've scored the pedal. In the past we've used a more in-depth rating system for pedals that includes a weighted score for multiple categories, but we feel this simpler system is easier to read and still gives you a generally accurate view of how the pedal performs.
IDEAL FOR: Clean tones, churches and Christian worship bands, pedalboards, recording
Overall Sound Quality
The ACS1 has three amp models and six cab tones to choose from, where any of the three amps can be paired with any of the six cabs.
Tone is crisp, clear and full with plenty of low-end in the EQ. It doesn't sound thin or weak, like you might get from cheaper amp modeling stompboxes. You're getting a tone that sounds both full and bright at the same time. I was able to get plenty of sustain out of all three amp models, perhaps with a little less coming from the Dartford amp model which is a VOX AC30 remake.
The Fullerton, which is modeled after the Fender Deluxe Reverb, was probably the thickest and most warm of the three models, and sounded especially nice with the room control pushed higher.
Overall, the sound quality left little to complain about.
As I've already mentioned, the models are not designed for high gain, though I did add a distortion pedal to the front of my signal, which I'll get into later.
Amp Models Tone
As I've mentioned, there are three amp models in the ACS1, all digital algorithms meant to re-create a popular tube amp.
Fullerton: Modeled after the Fender Deluxe Reverb
This is probably my favorite of the three models, which gave the warmest response and the most usable clean tone. We dialed it in with some extra bass in the EQ and mids at about 60 percent. From there, we cut treble back until things smoothed out a bit, which sounded great for clean rhythm, open chords, and bluesy, John Frusciante-style clean lead.
London: Modeled after the 1962 Marshall Bluesbreaker
This amp model is a bit more articulate than the Fullerton, with brighter highs and more breakup. If you want to push gain on the ACS1, this is probably the amp model you should be using. It's not a full-throttle distortion sound, but you can definitely achieve a bluesy, Marshall-style breakup that sounds good with lead lines and classic rock riffs.
Dartford: Modeled After the VOX AC30
This is the brightest of the three amp models, which is a trademark of the VOX AC30 tone profile. It's got a sort of "jangly" quality that bites a little on the high end, and provides a little less sustain than the other two models. It's also particularly clean without getting a ton of response from moving the gain control up. You might get some subtle breakup, but that's about it. If you want to dial back the intensity, just move the treble back and give bass a little boost, maybe to around 40-50 percent.
There are a total of six cab models or impulse responses (IRs) that come loaded on the ACS1. They are broken down into front cabs and back cabs. The back cabs can be accessed by holding down the bypass switch and moving the selector switch to a, b, or c. The front cab can be more easily selected by simply moving the selector switch.
- Fender Deluxe Replication
- Two Rock Creamback Replication
- VOX Blue Back Replication
- Fender Super Reverb Replication
- Marshall 4 x 12 Replication
- VOX Green Back Replication
The cab models are a little harder to pin down. I liked the two Fender replications and the Marshall 4 x 12 the most. Other cab models were hit or miss, depending on what kind of tone you're trying to dial in. I should point out that this significantly increases the variety of tones you're able to achieve, where I've used some amp and cab modelers where the cab you select doesn't make a ton of difference in what you end up hearing.
That is not the case with the ACS1, as the cabs actually make a big difference in the tone you hear, both from the headphone jack and the mono output going into studio monitors.
Still, I didn't love all the cabs, which is why I say they were hit or miss.
But that's a preference issue and not a quality issue. Walrus Audio did a great job getting a wide variety of cab models into the mix and giving them each their own distinctive tone qualities.
The ACS1 gives you the same basic control scheme that you would find on an amplifier, primarily the following:
- Three-band EQ
- Gain and volume
- Room (size of room algorithm, but equates to a reverb control)
I found myself using the following settings most often:
- Volume around 50 percent
- Low gain (15 percent or less)
- Room around 30 percent
- Bass around 60-70 percent
- Mids around 60 pecent
- Treble around 40 percent
Most of this is just a matter of taste. I like a more warm and mellow tone with less bite, so I found myself dialing back the treble control and giving a little more bass in most cases.
However the gain control staying low was mostly because turning it up doesn't give you a ton of distortion. Instead, it mostly just increases the volume of the preamp model. Instead of pushing gain higher, I would just turn up the volume if I wanted a higher output from the pedal.
It's possible to get some breakup from the ACS1, especially on the London amp model, but I didn't find it to be a strength of this pedal at all.
I was much happier with it when dialing in clean tones and then letting my pedalboard do the rest of the heavy lifting.
There are two inputs and two outputs on the ACS1, where the most intriguing feature is that you can set different amp models for different sides, if you're running a stereo connection. Using the L + R switch, you can either set the same amp model for both sides or a particular model for the left and right sides.
If you don't run a stereo connection - which I did not - you just use the mono output and run one amp/cab model at a time.
For my Walrus Audio ACS1 review, I did not test the stereo output, therefore I could not split the amp models. Though for those that do run a stereo connection, it's an easy thing to set up.
There are three onboard presets for the ACS1 and a total of 128 preset slots if you choose to use a MIDI controller. For testing, I did not use any kind of MIDI connection with the Walrus Audio ACS1.
To recall a preset, you simply step on both bypass switches at the same time, which cycle between red, green, and blue LED indicators.
If you want to save a preset, navigate to the preset (LED color) you want to override, dial in the settings you want, then hold down both switches until the LEDs stop blinking.
Walrus Audio deserves some credit for getting three onboard presets into this pedal, especially when much larger boxes like the Line 6 DL4 also only have three. While you might not use these presets as much in an amp modeler without effects, it at least lets you store and try different amp or cab combinations, perhaps if you find a few you really like and keep going back to, which I certainly did.
To test the ACS1 I did use headphones quite a bit, which is a huge perk of this particular box with a headphone out directly on the pedal. This is an eighth inch headphone jack that I used with a pair of Status Audio studio headphones. I'd definitely recommend using headphones that have a fairly long cable as the shorter one I used was pretty annoying and pulled the pedal around when I moved.
But from a sound quality perspective, there was nothing to complain about. The setup sounded absolutely fantastic.
Studio Headphones (large form)
Studio headphones with the large earcups sound best, and are what I would recommend if you plan to directly monitor the ACS1. Note that the eighth inch headphone jack will need an adapter if your headphone jack is quarter inch, though most are eighth inch jacks.
Earbud Style Monitors
The second option would be an earbud style or in-ear monitor. We tested these briefly with the ACS1 with fairly good results, though the sound is significantly nicer with the large studio headphones.
Studio Monitors (Mackie pair)
As I've mentioned, the studio monitors I used to test the ACS1 are a pair of cheaper Mackie Studio monitors with a USB audio interface. The signal comes out of the ACS1 and goes into the interface, which then pumps the signal out through the speakers. I felt like there was a little bit of a quality dip going from the headphones to the monitors, but that could just be because I'm not using a super expensive setup.
Overall, the ACS1 going into the studio monitors sounded fine and could even handle higher distortion tones when I added in a distortion pedal.
Final Thoughts & Questions
So, could the ACS1 replace an amplifier? In a lot of situations, I would say absolutely, yes. It can't replace a solid distortion source, but for many buyers of the ACS1, it might not need to.
We recommend it for clean tones, bluesy styles, and those bringing a stacked pedalboard into the equation. If you can get your distortion from a different pedal, the ACS1 will put down a reliable clean tone to serve as a base for the rest of your effects.
From the ACS1, going into an audio interface, mixer, or PA system isn't really going to matter.
It'll do the work of sounding like a real amp, and giving you some better than decent tones to work with.
If you have questions about our Walrus Audio ACS1 review, or about our process, feel free to drop those in the comments section below.