The Best Free Synth Plugins That Actually Rip

Searching for a "free synth plugin" can feel like digging through a bargain bin full of cracked plastic and disappointment. But every now and then, you find a gem—a tool that’s not just free, but genuinely powerful enough to carve out a permanent spot in your DAW.

In modern metal, synths are no longer just an afterthought. From the industrial chaos of Rammstein and the atmospheric layers in recent Periphery tracks to the pulsing electronics that drive bands like Bring Me The Horizon, synths are a crucial part of the sonic assault.

But let’s get one thing straight: having the "right" plugin is only half the battle. Just like a guitar tone depends more on the player, the pickups, and the DI signal than the specific amp sim, a killer synth sound comes from your decisions. That said, starting with a powerful and flexible instrument makes a world of difference.

Here are four free synth VSTs that absolutely rip, plus some actionable tips on how to dial them in for a brutal metal mix.

Vital: The Free Wavetable Monster

If there’s one free synth that has completely changed the game, it’s Vital. This is a full-blown wavetable synthesizer that goes toe-to-toe with paid giants like Xfer's Serum. For producers making any kind of modern, aggressive, or electronic-infused metal, this is a non-negotiable download.

Why It Rips for Metal Production

Vital’s visual interface is incredible. You can see your wavetables, filters, and LFOs moving in real-time, which makes designing complex, evolving sounds intuitive. For metal, this means you can craft everything from churning, modulated basslines that sound like a machine tearing itself apart to eerie, dystopian pads that add a cinematic layer to your intros and bridges.

Actionable Tip: Creating a Gnarly Modulated Bass

1. Oscillator 1: Start with a basic saw wave. In the wavetable editor, use a modifier like “Harmonic Stretch” or “Wavefold” to add some aggressive upper harmonics.
2. Oscillator 2: Load up a sine wave and pitch it down an octave (-12 semitones). This will be your sub-bass foundation. Keep it clean.
3. LFO 1: Set your LFO to a 1/8 note sync rate. Drag and drop this LFO onto the level (volume) of Oscillator 1. Now you have a basic rhythmic pulse.
4. The Gnarl: Now, drag that same LFO onto the wavetable position of Oscillator 1. Don’t apply it fully—just a little bit. You’ll hear the timbre of the bass "wobble" in time with the volume pulse. For extra grit, drag it onto a filter cutoff or a distortion drive knob in the Effects section. You now have a complex, rhythmic bass that can carry an entire industrial-style riff.

Surge XT: The Deep-Dive Powerhouse

Don't let the simple interface of Surge XT fool you—this open-source synth is an absolute beast. It’s the kind of plugin a sound design nerd could get lost in for weeks. It won’t hold your hand, but if you’re willing to experiment, the sonic possibilities are nearly endless.

Why It Rips for Metal Production

Surge XT excels at creating massive, layered textures. Its dual-scene architecture means you can essentially run two separate synths in one instance, making it perfect for huge, wide stereo pads or complex, evolving drones. It’s also surprisingly CPU-friendly for how much it can do. Think of it as the tool for creating those unsettling, atmospheric soundscapes that sit behind a wall of guitars.

Actionable Tip: Building a Dystopian Pad

1. Scene A: In the Oscillator section, select something with some movement, like the “S&H Noise” type or a "Window" wavetable.
2. Filter: Route it through a Low Pass 24dB filter. Keep the cutoff fairly low to start.
3. LFO Time: Assign a very slow LFO (like a 4-bar sync rate) to the filter cutoff. Now the sound will slowly open and close, creating a sense of dread.
4. Scene B: Click over to Scene B and create a contrasting sound. Try a simple Saw wave pitched up an octave (+12). Apply a fast, frantic LFO to its pitch (just a tiny amount!) to create a feeling of instability.
5. Effects: Pan Scene A slightly to the left and Scene B to the right. Run the whole thing through Surge’s built-in ‘Reverb’ and ‘Delay’ effects to push it into the background of your mix. The result is a wide, complex pad that feels alive and unsettling—perfect for a breakdown or an epic chorus.

TyrellN6 by u-he: The Analog Vibe

From the brilliant minds behind paid legends like Diva and Zebra2, u-he’s TyrellN6 is a gift to the production community. It’s designed to emulate the character of classic analog hardware synthesizers. It’s simpler than Vital or Surge, but what it does, it does with incredible quality and vibe.

Why It Rips for Metal Production

Sometimes you don't need a crazy, modulated wavetable monster. You just need a solid, powerful TONE. TyrellN6 is perfect for classic synth sounds: thick mono-leads for solos, fat sub-basses to reinforce your low end, and warm, dark pads. If you’re trying to add a touch of ‘80s synthwave or classic prog rock to your metal mix, this is your tool.

Actionable Tip: The Perfect Sub-Bass Layer

Heavy guitars, especially on 7 or 8-string instruments, often have a ton of low-mid information but can lack that foundational, chest-thumping sub-frequency. An unapologetically simple sub-bass synth is the perfect fix.

1. Oscillator 1: Set it to a pure Sine wave.
2. Oscillator 2: Turn it off completely. You don’t need it.
3. Filter: Open the filter cutoff all the way up, or just bypass it. You want all those pure, low frequencies.
4. Envelope: Set the ADSR envelope to a simple "on/off" shape. Instant attack, full sustain, and a quick release.
5. How to Use It: Program a MIDI line that perfectly follows your song's root notes, especially during chugs and breakdowns. Tuck this synth track low in the mix, just enough so you feel it more than you hear it. It will add immense weight and power without muddying up your guitars.

Okay, But Do The Plugins Really Matter?

It’s easy to get lost in "Plugin Acquisition Syndrome," hoarding hundreds of VSTs in the hope that the next one will be the magic bullet. But the truth is, the world's best mixers—many of whom you can watch in the Nail The Mix sessions catalog—could make a killer mix with stock plugins.

The philosophy is simple: your skills are more important than your tools.

Skills Over Shiny Objects

It’s better to deeply learn one or two synths like the ones above than to have a hundred you barely understand. When you see producers like Jens Bogren or Joey Sturgis use a specific tool, it's not because the plugin is magic; it's because they have thousands of hours of experience and know exactly what they want to achieve. They could get 99% of the way there with any decent tool because they've mastered the fundamentals of synthesis, EQ, and compression.

Watch Out for Latency and Phase

Here’s a technical point to keep in mind: every plugin introduces a small amount of latency (delay). Most DAWs have Automatic Delay Compensation to handle this, but it’s not always perfect, especially with heavy parallel processing.

If you’re running a synth bass parallel to a DI bass, and one chain has more latency, you can get nasty phase cancellation that sucks the life out of your low end. This is why many old-school Pro Tools users developed a habit of using minimal busing—the delay compensation used to be notoriously bad. Be mindful of this. If something sounds weak or thin when it should be powerful, check for phase issues between parallel tracks.

Don't Chase "Unique," Chase "Good"

Worrying about whether using Vital makes you sound like everyone else is like worrying that two chefs using the same salt will make the same dish. It's nonsense. Your "sound" comes from the sum of your choices: your note selection, your sound design, your effects chain, and how you make that synth sit in the context of your song.

Your taste is already unique. You are a product of all the music you've ever loved. Trust that. Focus on getting skilled with the tools you have, and your unique voice will come through automatically. You can't stop it.

The real work is in learning the craft. These free synths are more than powerful enough to get you a pro-level sound. The rest is up to you. Spend time with them, learn their ins and outs, and focus on one thing: making killer music.