Mr.Warmer, CA-72, and True AB: 3 Free Plugins Worth Grabbing This Week
Mr.Warmer Puts a Mid/Side Switch Where Most Free Saturators Don't
MrMoustache, the Barcelona-based plugin brand behind a run of small, focused free tools, released Mr.Warmer on October 7. It's a 12AX7-modeled tube saturation plugin, and the headline feature for bass work isn't the saturation itself — plenty of free plugins do warm-up saturation — it's that the Mid/Side dial is a first-class control, not buried in a context menu.
The control set:
- Level and Color knobs, with a Color Boost switch for pushing further into saturation
- A Mid/Side dial (0–100%) that lets you aim the saturation at the center channel only, the full stereo signal, or the sides only
- A Tilt EQ that shapes the tone going into the saturation stage, before it hits the tube model
- A Mix knob for parallel blending
- Up to 8x oversampling, with automatic gain compensation so cranking Level doesn't just make things louder
Formats are VST3 and AAX on both Windows and macOS, plus AU on macOS — all 64-bit, no 32-bit versions. Mac requirement is 10.13 or later, Intel and Apple Silicon both covered. No account, no email gate, no time limit on the free license.
Why this matters for bass specifically: most saturation plugins process everything you feed them, left and right, equally. If your bass is sitting dead center (as it usually should be for mono-compatibility reasons), running the whole stereo bus — bass included — through a saturator that also hits the wide stuff around it means you're either under-saturating the bass to protect the sides, or over-saturating the sides to get the harmonic content you want on the low end.
Mr.Warmer's Mid/Side dial sidesteps that. Drop it on your bass bus, or even on a group bus carrying bass plus a few other centered elements, and dial toward Mid-only. You get the harmonic thickening on the low end without touching whatever's panned out to the sides. The Tilt EQ is worth using here too — tilt it to favor the low-mid band before the signal hits the tube stage, and you're saturating the harmonics that actually make a bass line feel bigger (100–400 Hz) rather than just adding fizz on top.
One caution: Color Boost gets aggressive fast on low frequencies. A setting that sounds like a nice edge on a mid-range synth can turn muddy or papery on a sub-heavy bass part. Start with Color Boost off, dial in Level and Tilt first, and only reach for Boost once you know the baseline tone is where you want it.
CA-72: A Free, Open-Source Minimoog Recreation You Can Actually Read the Code For
Idle Foundry's CA-72, released October 6, is a from-scratch recreation of the early-1970s Minimoog Model D — and unlike most synth emulations in this space, it's released under GPLv3, with the full source available on GitHub. You're not getting a locked binary with a free license; you're getting a synth you (or anyone) can inspect, modify, and recompile.
What's actually in the box:
- Polyphony from 2 to 10 voices — the original Model D was monophonic, so this is a deliberate departure, not an emulation detail
- Entropy controls across tuning, filter, and envelope, which introduce small, musical variation between voices so stacked notes don't sound perfectly identical
- Stereo spread for polyphonic voicing
- A feedback control that routes the model's "headphone" output back into an external input stage, mimicking the real unit's quirky feedback-patching behavior
- 24 factory presets with tagging and search, plus the ability to save your own patches
Formats are VST3 and CLAP only — no AU, so Logic and GarageBand users are out, and no AAX for Pro Tools. It runs on macOS 11+ (Intel and Apple Silicon), Windows 10/11 64-bit, and Linux x86-64. No purchase, no account, nothing to sign up for. Download sizes are small: roughly 9 MB on Mac, 15 MB on Windows, 22 MB on Linux.
For bass work, the obvious starting point is also the most important caveat: keep Poly mode at 1 voice (or close to it) for anything you want to function as a bass part. The Minimoog's reputation as a bass synth comes specifically from its mono ladder-filter low end — stacking 4 or 5 voices with Entropy cranked turns that same engine into a pad or a unison lead, and the low end gets diffuse fast. If you want width and thickness on a bass line without losing low-end focus, raise voice count modestly (2–3) and keep Entropy low — enough to avoid a perfectly static, phasey stack, not so much that the fundamental starts wandering.
The feedback control is worth exploring on bass too, but sparingly. Small amounts add a bit of grit and harmonic complexity to an otherwise clean low end; pushed too far it starts eating into pitch stability, which is the one thing you don't want to compromise on a part doing foundational work in a mix. CPU usage scales directly with voice count, so if you're running CA-72 across several tracks, higher polyphony settings are where you'll first notice dropouts — another reason to default low on bass tracks specifically.
True AB: A Referencing Tool for Checking How Bass Actually Translates
Rapid Flow's True AB Referencing, out October 5, is built around a problem every bass-heavy mix eventually runs into: it sounds great on your monitors and falls apart — or disappears — on a phone speaker, a car system, or a bad bluetooth speaker. True AB lets you load up to five reference tracks, A/B against your own mix, and auto-matches perceived loudness so you're comparing tone and balance rather than just "whichever one's louder wins," which is how most informal reference checks go wrong.
A flag up front, same as we'd flag any promo: True AB is not permanently free. It's normally a $39 plugin, currently offered free with what Rapid Flow describes as a perpetual license, and the developer hasn't announced an end date for the promotion. Getting it also requires creating an account and signing up for the developer's email list — the download and browser-based activation (no iLok) are gated behind that signup. If you don't want another account or newsletter, this is the one of the three to skip; Mr.Warmer and CA-72 above have no such requirements.
If that trade-off is fine with you, the feature most relevant to bass work is the five playback models: phone, car, a deliberately bad "grotbox" speaker, nearfield monitors, and a club system. Flipping between those while your bass-heavy mix plays lets you hear, in a rough approximation, where your low end actually survives and where it's getting lost or turning into unpleasant distortion — a club system model pushing low frequencies your nearfields can't reproduce is a useful gut-check before you assume a bass part is sitting correctly.
The built-in LUFS/peak/RMS metering and spectrum analyzer let you confirm what you're hearing rather than just trusting your ears across different speaker models, and the mono/side monitoring option is directly useful for bass: solo to mono and listen for whether your low end holds together or thins out, the same mono-compatibility check that matters whenever a bass part isn't dead-center (see our notes on this in the Shifter and Multiband Dynamics posts). The delta highlight — showing exactly where your mix's frequency content diverges from the reference track — is a faster way to spot "my bass is 3 dB hotter than the reference at 80 Hz" than eyeballing two separate analyzer windows.
Worth Grabbing, With One Caveat
Mr.Warmer and CA-72 are both straightforward free downloads with no strings attached — if you do any bass saturation or want a mono-first analog-style bass synth to experiment with, there's no real reason not to grab both this week. True AB is genuinely useful if you're serious about checking how your low end holds up outside your studio, but go in knowing it's a time-limited promotional offer gated behind an account, not a permanent free tool.
If you're building out a free-plugin folder specifically for bass work, it's also worth remembering Low End Candy has two of its own completely free tools worth a look: Ratchet for rhythmic gating and stutter effects, and The Clap for a dedicated clap/snare layering tool — both free, no account needed, no catch.