Keeley Electronics Seafoam Plus Review – Best Digital Vibrato/Chorus Pedal?

By Jake Behr –

Review of: Keeley Seafoam Plus Chorus Vibrato

Reviewed by: Rating:4.5On May 21, 2016Last modified:April 23, 2017



Where I’m at as a musician I often find my tonal progress ensnared in that familiar gear-head beartrap, obsessing over effects that could make my guitar sound less like a guitar and more like an organ (or a spaceship, or a fart) with no hope of moving forward without having said effect in my arsenal. I can’t help but envy the latest doodad with every imaginable feature, letting simpler, tried-and-true circuits fall by the wayside in favor of the most “textural,” which is a sometimes nonsensical term in my world. Usually, these pedals languish on my pedalboard uselessly until one of my bandmates calls me out on the poor use of real-estate, and I end up with a pedal I shouldn’t have bought and a guitar that sounds like… a guitar.

That said, over the last few days I’ve become strangely rapt with what most guitarists would consider a very traditional effect: a chorus. Contain your recoil. One would be right to defend the validity of the effect by invoking the names of the most celebrated guitarists who used it: for example, Nile Rodgers used a liberal coating of chorus to great party-inflicting effect in Daft Punk’s 2013 banger, Get Lucky. I’ll even go one step further and declare: this is not just any chorus. Robert Keeley has set the bar for the effect and any chorus and/or vibrato I vet will ever be subject to the Keeley Engineering Seafoam+ standard.

Keeley Electronics is famous a thousand times over for their outstanding compressor pedals, but they’re far from a one-trick pony and this guitar pedal is just one of several pieces of evidence that prove that fact. Put simply: I am in love with an effect that makes my guitar sound like more guitars.


Mono In/Out

Rugged metal enclosure

Tiny Footprint

4 knobs controlling Rate, Depth, Mix and Space/Tone (depending on voice configuration)

Rate: Controls the speed at which the signal is modulated.

Depth: Affects the pitch modulation of the wet signal.

Mix: Determines the amount of affected signal is blended with your dry guitar signal.

Space/Tone: More on this later.

3-position switch for voice control (1) Dimension Chorus-Automatic Double Tracker (2) Seafoam Plus Chorus (3) Dual Seafoam Plus Chorus

2 internal dip switches allowing for Guitar/Bass and Modern (t/Vintage (Warm) modes

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Sound & Performance:

Keeley Engineering first debuted the Seafoam+ at Winter NAMM 2014 as a sequel to their popular Seafoam Chorus. When BGFX originally set eyes on it, it was housed in a stereo, double-pedal-sized enclosure with a dedicated vibrato setting and delay/gain knobs to replace the original Seafoam’s blend knob. Keeley has since cut down on the footprint and added two voices in addition to an updated Seafoam algorithm. The latest consumer iteration is a small, mono box made out of a textured navy blue metal, featuring four knobs and a center switch that controls which of the three operable voices you’re using. Under the hood, there’s two dip switches that allow the user to change the algorithms to an onboard bass configuration and the tone from “Modern” to “Vintage.” The face appears to be screen printed with a white and (appropriately) seafoam green enamel logo. I have to say, the Seafoam+ boasts one of the nicest enclosures I’ve had my hands on and the footprint is unimpeachably tiny.

Keeley-Electronics-Seafoam-Plus-Review-Best-Digital-Vibrato-Chorus-Pedal-02Plugging in to this pedal I quickly discovered that I would struggle to find a setting I didn’t like. Despite its digital nature, the tone is comparable to a very clean high-end analog circuit. For those of us who appreciate the flavors of the past, the aptly titled Vintage option on the dipswitch adds a layer of warmth to the affected signal, making for a very buttery tone in all six voice settings without relinquishing clarity.

Out of the box my Seafoam+ was set to ADT, which stands for Automatic Double Tracker. According to Keeley’s website, this “True Chorus” functions like an actual three-piece choir, duplicating your guitar signal into three independent voices that resonate at different pitches and rates. This makes for some very plump chorus that sounds like what chorus should have sounded like a long time ago. What’s even better about this configuration is that it implements Keeley’s Abbey Chamber Reverb algorithm via the Space knob for a smeared-out, full tone that invokes pelagic imagery. I couldn’t find a vibrato sounding effect in the ADT voicing no matter what I did, which I guess does make sense due to the 3-voice nature of the chorus.

In Bass Mode, ADT is converted to a relatively basic flanger with feedback control allowing for additive or subtractive flange. I’ll be honest: I’m not a huge fan of flange in general and when I first discovered that Keeley opted to include a flange in the Seafoam+, I was skeptical. However, the simplicity of the Seafoam’s interface made it very easy to find a tasteful tone, and I might soon become a flange convert because of that fact. Of course, with the space knob at its extremes you can achieve some pretty wild modulations and I had fun making airplane sounds by maxing the negative/positive feedback.

Below ADT on the voice switch is the updated Seafoam+ voicing, a very clean and classic-sounding chorus. The algorithm relies heavily on an LFO and is based on a vintage Bucket-Brigade Delay analog-chorus circuit, so if you’re expecting that ramping pitch modulation that makes your sound throb, you won’t be disappointed. The mix and depth knobs can be brought clockwise for watery vibrato, and counterclockwise for a more chorus-y sounding effect. The space knob is also repurposed to function as a tone control for warmth or clarity in the wet signal. Bass mode simply changes the frequency response to accommodate more low-end applications. There isn’t much further to say there, but I did notice it added a bit more body to the low-end and played very nicely with overdrive.

The last setting on the voice switch is the Dual Chorus, which I tend to gravitate toward when I’m playing with the Seafoam+. It splits the frequency modulation into two bands, allowing for crazy saturated flux in the low end and absolute peace in the highs, or vice-versa. The Space knob is once again repurposed, allowing you control over which frequency band is being affected. This setting is actually what sold me on the Seafoam+. I have an especially bassy overdrive-fuzz on my ‘board that is so completely made by the Dual Chorus that I might just put them both in the same effects loop and use them together exclusively. The pulsating chorus underneath (or on top of) my signal left me wishing that Keeley had kept the stereo in/out for an even fuller sound but you can’t even count that as a detraction from the model itself. The effect is profound even in mono and this voice stood out to me as particularly expressive, achieving wide, boomy ambience and jarring vibrato with deft simplicity.



The Keeley Seafoam+ Vibrato/Chorus is more quality bang for your buck than most digital chorus pedals on the market (including the original Seafoam) dream to be. With six unique voices on board, an MXR-sized footprint, the extended dipswitch options, and the more-than-reasonable price, the Seafoam+ isn’t just new and improved: it’s unique from its predecessor. It sounds awesome on its own, but my biggest impediment writing this review was the amount of time I spent just listening to the way the Seafoam+ made my other effects shine. You can go the traditional route and use it to pop your leads out of a mix or you can get weird and use it to bury your signal in wavering, watery wobbles. I do wish that Keeley had kept the Seafoam+ a stereo model to add further girth to its capabilities and maybe included an expression in for the sake of controlling the rate of the modulations in real-time, but neither of these concerns detract enough from the current iteration to affect my overall opinion: the Keeley Engineering Seafoam+ Chorus/Vibrato is a top-notch effect, and you should play it to hear so for yourself.

That concludes our Keeley Seafoam+ Vibrato/Chorus review. Thanks for reading.


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Jake Behr


  1. Seth Rosenthal

    July 5, 2016 at 8:17 am

    Nice review, cool pedal.

  2. Evgenii K

    June 16, 2016 at 1:04 am

    Hi Jake! Just saw your review on Youtube and it’s great. last time i skipped this pedal when it came out – now I see beauty of sea foam. Thank you!

    • Jake Behr

      June 18, 2016 at 7:34 am

      Thanks for watching! I’m glad I could be of help, the Seafoam+ really is a great little machine.

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