KERN SMOOTH vs oeksound Soothe 3: $29 vs $259

why this guide exists

oeksound built the original soothe in 2016, then refined it into Soothe 2, the plugin these comparisons, mine included, keep measuring everything else against. Soothe 3 shipped May 19, 2026 at $259 and raises the floor of what the category can do, with a redesigned dual-mode engine and a true zero-latency tracking mode.

i make KERN SMOOTH, a $29 resonance suppressor that picks a different fight: psychoacoustic processing across 40 ERB-spaced bands, M/S routing, no iLok, published algorithm notes, including the papers it is built on. this guide compares the two honestly. where Soothe 3 is the better tool for your work, i will say so.

(reading someone else’s plugin comparison is like reading someone else’s restaurant review. useful, but your ears are yours.)

what changed in Soothe 3

oeksound describe soothe as dynamic resonance suppression with adjustable depth and selectivity and a soft / hard mode toggle. they do not publish the internals beyond that, and i am not going to guess at them. Soothe 3 redesigned the engine around the two-mode split rather than treating modes as a setting:

• Soft mode (adaptive threshold). the new default. an adaptive threshold makes Soft a sane default on most sources. oeksound’s own manual still warns that extreme settings can be heard, so it is forgiving rather than foolproof. described by oeksound as the most transparent resonance suppression they have shipped.
• Hard mode (fixed threshold). carries forward the Soothe 2 behaviour. more reactive to dynamics, more obviously compressor-like, and the right pick when the goal is the aggressive de-resonance grab Soothe 2 became known for as a creative effect.
• Low Latency mode. zero samples of added latency at base sample rates, about 1 ms at higher sample rates. real, not just lower. this is the headline workflow change.
• Single Detail parameter, folding in what Soothe 2 split across Sharpness and Selectivity. one control, calibrated to keep the previous range of behaviour available without two interacting knobs.
• Tilt controls for tailored low-end response, sitting alongside the main parameters.
• Linear Phase option in two clicks, for situations where the minimum-phase artifacts of the default mode matter.
• Multichannel support up to 9.1.6 for immersive and surround work.

what Soothe 3 has not changed: the iLok account lock and the premium positioning. oeksound still do not describe any perceptual frequency weighting, though absence from a manual is not proof of absence in the code. price moved from Soothe 2’s $199 to $259 retail, with a $55 upgrade from any previous Soothe.

what SMOOTH does differently

SMOOTH is not trying to be Soothe 3 at a lower price. the engine is built around two architectural choices that change what the plugin sounds like.

ERB-domain bands

the human ear does not hear in linear frequency. the cochlea has roughly logarithmic resolution: critical bandwidths widen as frequency rises. a 50 Hz-wide feature at 200 Hz spans several auditory filters; the same 50 Hz at 8 kHz sits well inside one, because the filter up there is about 890 Hz wide. a linear-frequency layout gives both the same number of bins, though what a given processor then does with them depends on its own thresholds and Q.

SMOOTH’s 40 bands follow the Equivalent Rectangular Bandwidth (ERB) scale derived by Glasberg and Moore.[^1] bands track the width of the ear’s auditory filters, narrow low down and wider as frequency rises, so each band covers about one unit of what you resolve rather than a fixed slice of Hz (sub-bass and high air). SMOOTH weights per-band sensitivity with the ISO 226 equal-loudness contour at 60 phon, so the same physical peak counts for more around 3 kHz than it does at 80 Hz. how much suppression follows still depends on DEPTH, SENS and the material. the math matches how you actually hear the problem.

M/S routing

SMOOTH processes mid and side channels independently when M/S mode is on. a sibilance resonance that sits in the centre image of a stereo vocal can be suppressed without touching the spatial reverb tail in the sides. resonance suppressors that work only on stereo signal cannot make this distinction.

(M/S is not a given at this price. it is not rare in the category, and soothe 3 has it too.)

no iLok

SMOOTH activates once via Lemon Squeezy on first launch, caches the license locally, and runs offline after. it re-checks about once a month if you happen to be online, and stays licensed if that check fails or never happens. no iLok account, no dongle, no nightly online check. for studios that travel or run an air-gapped mastering room, this is decisive. to be clear about the comparison though: soothe 3 licences cover more than one machine too, so this is about the activation mechanism and the offline behaviour, not about having to buy it twice.

the comparison table

sound: where the two diverge

Soothe 3 shipped the day this article went live. i have not yet had it on a real session long enough to publish a fair head-to-head listening write-up. i will update this section with real material once i have. what follows is an architectural prediction, not a verdict.

what the architectural choice should produce, source by source:

• on vocal sibilance, both should land cleanly. Soothe 2 already did, and the new adaptive Soft mode in Soothe 3 is built specifically to make the safe starting-point case easier. SMOOTH catches the same 3-4 kHz region because that range sits inside multiple narrow ERB bands. expect the difference to be small on isolated vocal lines.
• on acoustic body resonance (the 200-800 Hz problem), ERB weighting should concentrate SMOOTH’s response inside one or two bands. how Soothe 3 distributes its response there is not something oeksound publish, so i am not going to guess. both will remove the resonance. the surrounding low-mid balance will read slightly differently.
• on a centred resonance with stereo content sitting around it (the synth pad, the stereo guitar bus, the wide vocal double), M/S routing is what you want. i had this section wrong: soothe 3’s own manual documents a stereo section with left/right AND mid/side operation, so this is not a SMOOTH-only capability and i am not going to pretend it is. both will let you work on the mid alone. pick on the rest of the comparison, not on this. decisive.

the point is not that one plugin wins. the point is that you can hear the architectural choice. ERB processing concentrates suppression where ears notice; M/S keeps resonance work out of the parts of the stereo image you want to preserve. those are the two SMOOTH-side levers. on routine vocal and instrument cleanup the audible distance to Soothe 3 should be smaller than the 9x price gap suggests.

features compared, point by point

latency

Soothe 3 ships a real Low Latency mode: zero added samples at base sample rates, about 1 ms at higher sample rates. that is an alternative DSP path built for tracking and live use, rather than a setting you turn down. for a spectral suppressor at this quality level, true zero-latency tracking is a real workflow change, and it is the reason i would consider the upgrade if i tracked through one.

SMOOTH’s HQ path runs a fixed 4096-sample FFT at 44.1 kHz, about 93 ms. the DAW compensates automatically when mixing, but that is too much for live monitoring, which is what the opt-in LIVE mode at roughly 23 ms exists for. if you record vocals through your suppressor, Soothe 3 wins this round outright.

transient handling

Soothe 3’s adaptive-threshold Soft mode is built to keep the suppressor from over-correcting on transient peaks: the threshold moves with the source instead of sitting at a fixed line. SMOOTH solves the same problem with frequency-dependent attack times. bands above 5 kHz move faster than bands below 200 Hz, so transient sibilance sees a fast response while sustained body notes see a slower one. different solution to the same problem, both designed to avoid the classic “deep dip after every snare hit” failure mode.

sidechain

Soothe 2’s external sidechain is widely used for spectral unmasking, and Soothe 3 carries it forward. SMOOTH does not currently expose external sidechain. for ducking work, making the bass step out of the kick’s way automatically, Soothe wins this category.

if external sidechain is decisive, SMOOTH is not the plugin.

CPU

oeksound publish no CPU figure for either soothe 2 or soothe 3, and i have not measured one i would stand behind, so i am not going to put a number on theirs. SMOOTH targets under 3% on macOS at 44.1 kHz, single instance. i would not expect either to be the bottleneck on a modern machine, though neither of us publishes a figure you could plan a session around.

preset library

oeksound do not publish a preset count, so i am not going to invent one for the comparison. SMOOTH ships 32 presets covering common vocal, acoustic, and electronic sources. fewer, narrower in scope, and named directly (“De-Harsh Vocal,” “Acoustic Body,” not “Voice Special”). starting points, not finished sounds.

if you spend a lot of time A/B-ing presets to find a starting point, Soothe wins. if you set knobs from scratch by ear, the gap closes.

multichannel and formats

Soothe 3 supports up to 9.1.6 immersive configurations and ships VST3 / AU / AAX. SMOOTH is stereo-only and ships VST3 / AU (no AAX). if you work in Atmos, Pro Tools, or any post-production context that needs multichannel or AAX, Soothe 3 is the only one of the two that fits.

licensing and ownership

Soothe 3 requires an iLok account and the iLok License Manager (no physical dongle needed). one license covers three machines. it is sold outright or rent-to-own. SMOOTH activates via Lemon Squeezy: one-time online activation, then offline. it re-checks about once a month if you happen to be online, and stays licensed if that check fails or never happens. three device activations per key. a single SMOOTH license covers two studio machines plus a laptop without an account.

this is also where the price difference compounds. SMOOTH is $29 forever. Soothe 3 is $259 retail with a $55 upgrade from any previous version. the SMOOTH license pays for itself in one project. the Soothe 3 license pays for itself if zero-latency tracking, AAX, multichannel, or the established preset library is doing real workflow work for you.

decision framework

get Soothe 3 if

• you record vocals or instruments through your suppressor and the new zero-latency Low Latency mode unblocks that workflow.
• you work in Pro Tools and need AAX.
• you work in immersive or post (5.1 / 7.1 / 9.1.6).
• you already use Soothe 2 daily and the $55 upgrade for the adaptive Soft mode plus zero-latency mode pays back fast.
• you rely heavily on the preset library and the time-savings outweigh the license cost.
• you use external sidechain spectral ducking on a regular basis.

get SMOOTH if

• you want psychoacoustic precision (ERB-domain) at $29.
• you work on stereo material where M/S routing changes the decision (a centred resonance with stereo content sitting around it).
• iLok is a friction you would rather not pay for.
• you want lifetime ownership at single-plugin pricing and the budget back for something else.
• you mix more than you track, so the latency difference does not show up in your day-to-day work.

get both if

• you do high-volume vocal work (Soothe 3 on the lead, SMOOTH on the doubles or background harmonies, the licensing math works).
• you want to A/B the architectural choice on hard material and pick the cleaner result per source.

keep Soothe 2 if

• it is doing the job. Soothe 3’s additions are real (zero-latency mode is the genuine reason to consider the upgrade), but if you mix in the box and never tracked through Soothe 2 in the first place, the upgrade is optional. an existing soothe 2 licence is not withdrawn because the product was discontinued. i cannot promise how long oeksound will keep it running on future OS versions, and neither can anyone but them.

frequently asked questions

frequently asked questions

is KERN SMOOTH a real alternative to Soothe 3?

yes, for most resonance work. KERN SMOOTH at $29 uses 40 ERB bands mapped to human hearing, which is not a scheme oeksound describe for theirs, gives you native M/S routing, and runs under 3% CPU on macOS at 44.1 kHz. Soothe 3 at $259 adds the new adaptive-threshold Soft mode, a true zero-latency tracking mode, multichannel up to 9.1.6, and AAX for Pro Tools. my read, and it is a read rather than a measurement, is that for the routine job of taking harshness out of a vocal or a bright synth the gap in the result is narrower than the gap in the price. i have not run a level-matched blind test between the two, and until i do you should treat that as my opinion about my own plugin, which is exactly the kind of claim you should discount.

what is new in Soothe 3 vs Soothe 2?

Soothe 3 (shipped May 19, 2026) introduces two redesigned modes: Soft (adaptive threshold, transparent, and oeksound position it as ideal for most sources) and Hard (fixed threshold, more reactive, the compressor-like grab of Soothe 2). a true Low Latency mode adds zero samples at base sample rates (about 1 ms at higher rates). a single Detail parameter replaces the two-knob system. Tilt controls reshape the low-end response. a Linear Phase option is available in two clicks. multichannel support up to 9.1.6 is built in.

how much does Soothe 3 cost compared to SMOOTH?

Soothe 3 retails at $259 with a $55 upgrade from any previous Soothe. KERN SMOOTH is $29 forever with no upgrade fees. that is roughly a 9x price gap. Soothe 3 is also available rent-to-own; SMOOTH is one-time purchase only.

does SMOOTH support AAX for Pro Tools?

no. SMOOTH ships VST3 and AU on macOS plus VST3 on Windows. Pro Tools users on AAX should pick Soothe 3 or Rast Sound Tamer. AAX support is on the KERN backlog but is not on the v1.x roadmap.

does SMOOTH require iLok or an internet connection?

no iLok. no online activation calls during playback. SMOOTH activates once over the internet via Lemon Squeezy on first launch, caches the license locally, and runs offline after that. Soothe 3 requires an iLok account and the iLok License Manager (no physical dongle needed). if iLok is a hard no for your workflow, SMOOTH is built around that constraint.

should I upgrade from Soothe 2 to Soothe 3, or buy SMOOTH instead?

depends on what you actually use Soothe 2 for. if it is daily on every vocal session and the new adaptive Soft mode plus zero-latency tracking change your workflow, the $55 upgrade pays back fast. if Soothe 2 sits on a handful of tracks per project and the iLok account is friction you tolerate, SMOOTH at $29 covers a lot of that routine work for a fraction of the outlay. whether it covers YOUR routine work is a demo away, and i would rather you found that out than took my word.

does SMOOTH have a low-latency mode like Soothe 3?

yes. SMOOTH v1.4.0 added an opt-in LIVE mode that drops the reported latency to ~23 ms (1024 samples at 44.1 kHz). toggle it on in the plugin UI for tracking and monitoring. it will not match Soothe 3 zero-latency on paper, but it is usable for live work. existing license holders got it free.

references

a note from the developer

i bought Soothe 2 in 2019 and used it on every project for two years. it was the first plugin that made me think about resonance as a category instead of a series of static EQ cuts. the design taught me what the problem actually was. in that sense, oeksound did the field a service: they named a category and built the reference tool for it.

then i started reading hearing research. specifically, the Glasberg / Moore ERB papers, which i kept seeing referenced in DSP literature but never implemented in the plugins on my drive. i do not know why ERB-domain processing is rare in this category, and i am not going to invent a reason on other developers’ behalf. what i can say is that the perceptual work is decades old and well cited, and that when i built on it the result was the plugin i wanted to own.

SMOOTH is what happened when i tried to write the suppressor i wished i owned: ERB-spaced bands, M/S routing, no iLok, $29 forever. it is a different design choice landing at a different price point. the honest version of this guide is that for routine resonance work (vocals, acoustic instruments, bright synths on a stereo mix), my honest guess is that the audible gap is narrower than the price gap, but it is a guess: this page says elsewhere that the real session A/B is still owed, and it is. for tracking through the suppressor, AAX in Pro Tools, immersive work, or external sidechain ducking, Soothe 3 is the better tool today. the LIVE-mode update (v1.4.0) closed some of that latency gap. ~23 ms is not zero, but it is a quarter of the standard mode. honesty matters more than the sales pitch here.

soothe 3 costs nine times what SMOOTH does, which makes this the comparison i am least able to be neutral about. if you own both, push back: jonas@kernaudio.io.