How to use MIDI “key spikes” to trigger drum gates

Nail The Mix Staff

Ever fought with a gate that just won't open consistently on soft hits, or a compressor that reacts erratically to dynamic drum performances? You're not alone. Getting drum dynamics perfectly controlled can be a battle. But what if you could tell your gates and compressors exactly when to act, with surgical precision, every single time? That's where MIDI "key spikes" come in, a game-changing technique championed by producer Machine (known for his work with Lamb of God, Suicide Silence, and more).

Machine recently dropped some serious knowledge bombs, showcasing how he uses these phase-accurate MIDI notes to achieve unparalleled control over his drum mixes. This isn't just about clean gates; it's about unlocking creative possibilities that are nearly impossible with traditional audio-triggered processing. Let's dive into how you can implement this in your own sessions.

What Exactly Are MIDI Key Spikes and Why Bother?

At its core, a "key spike" is a phase-accurate MIDI note that you place on every single drum hit in your session. This MIDI note isn't meant to trigger a melodic instrument; instead, it's used to trigger a very short, consistent audio blip – the "spike." This spike then becomes the perfect, unwavering signal to key your gates, compressors, or even trigger samples.

Why go through this effort? Machine puts it simply: "utter perfect musical control."

  • Consistency: Audio-triggered gates and compressors rely on the input signal's level. A slightly softer snare hit might not open a gate, or a louder one might make a compressor overreact. Key spikes are always the exact same level, so your processors react identically every time.
  • Precision: Because the MIDI notes are phase-accurate to the drum transients, you can program your gates and compressors with incredible timing. Want something to duck out of the way a millisecond before a kick hits? Key spikes make it possible.
  • Musicality: You're no longer just setting a threshold. You can musically shape the envelope of your gated signal—adjusting attack, hold, and release to perfectly fit the song, regardless of the original audio's dynamics.
  • Creativity: This technique opens doors to unique sound design, like creating custom-triggered room effects or precisely shaping the decay of samples.

Setting Up Your Key Spikes: A Step-by-Step Guide

Alright, let's get our hands dirty. Machine emphasizes that this isn't a "quick mixing" trick; it's methodical, but the results are worth it.

Step 1: Choosing Your Source – The Snare Top is King

When generating MIDI from drum tracks, Machine starts with the top snare mic (often a Shure SM57). Why? He considers the top snare the "God" mic, the foundation around which other drum elements align. It's the primary voice of the kit, and its midrange character is what our ears naturally focus on. Using this as the timing reference ensures everything else locks in tightly.

Step 2: Generating the MIDI

There are several ways to convert your audio drum hits to MIDI:

  • DAW Built-in Tools: Logic Pro X has a “Replace or Double Drum Track” feature that analyzes audio and creates MIDI notes. Many DAWs offer similar functionality. Machine demonstrated this in Logic.
  • Dedicated Plugins: Steven Slate Trigger is a popular option that excels at this and can also host samples.
  • Older Tools (for context): Machine mentioned previously using a Pro Tools plugin called DTM (Drums to MIDI).

The Process:

  1. Select your source audio track (e.g., snare top).
  2. Use your chosen tool to analyze the audio and generate MIDI notes. Most tools will have a threshold setting; adjust this to ensure it's catching all the intended hits and ignoring bleed or noise as much as possible. This is easier on tracks with minimal bleed, like the isolated tracks Machine was working with.
  3. Crucially, manually check and clean up the MIDI. No automated process is perfect. Zoom in and ensure each MIDI note aligns precisely with the transient of the drum hit. Correct any misplaced notes, add missing ones (especially in fast rolls or flams if you want them spiked), and delete false triggers. Phase accuracy is key here! For very fast rolls, Machine sometimes chooses to leave them out of the key spike MIDI and automates his gates to bypass during those sections, letting the natural sound through.

Step 3: Creating the "Spike" Audio

Once your MIDI is perfect, you need to create the actual "key spike" audio signal.

  1. Route the MIDI track to a sampler.
  2. Load a very short, sharp sound into the sampler. Machine makes his own: "the tiniest little instantaneous on-off blip." The goal is something that's perfectly consistent in level and turns on and off as fast as possible.
  3. In your sampler settings, ensure:
    • Max Velocity: Set the sampler so that all MIDI notes trigger the sample at its maximum velocity. You don't want any dynamic variation here.
    • No Dynamics/Modulation: Turn off any velocity-to-amplitude or other dynamic modulations.
    • Loud and Clear: The spike should be loud enough to reliably trigger any processor.
  4. Print this MIDI performance to an audio track. This new audio track is your "Snare Spike," "Kick Spike," etc.
  5. Important: Set the output of these spike audio tracks to "No Output." You'll never actually hear these spikes in the mix. Their sole purpose is to be an internal trigger signal for other plugins via sidechain. Machine also color-codes these tracks for easy visual organization.

Creative Applications of Key Spikes

Now for the fun part! Here’s how Machine leverages these precision triggers:

Precision Gating Like Never Before

This is a primary use case. Take your snare track, for instance:

  1. Insert your preferred gate plugin (Machine often uses Logic's stock Gate).
  2. Set the gate's sidechain/key input to listen to your "Snare Spike" audio track. (In Logic, you'd select the spike track from the sidechain menu; Machine noted his Snare Spike was on channel 35).
  3. Since the spike is loud and consistent, you can set your gate's threshold very low (e.g., -80dB). It will only open when the spike occurs.
  4. Now, you have complete musical control over the gate's Attack, Hold, and Release times. You can make the snare snap tight or let it ring out, perfectly in time, without worrying about bleed from cymbals or toms messing with the detection. Machine demonstrated cleaning up tom bleed from the snare track effortlessly.

This technique is invaluable for all drum shells, cleaning up bleed and shaping the decay precisely. For other layers like room mics or bottom snare, you can even slow the attack of the gate slightly to get them "out of the way" of the initial transient of the main mic, creating more impact.

Surgical Ducking and Dynamic Control with Compressors

Key spikes aren't just for gates. They are incredibly powerful for keying compressors for ducking or other dynamic effects.

  • Kick & Bass: Create a "Kick Spike (All)" track that combines spikes from all kick drum mics. Use this to key a compressor on your bass guitar track. You can make the bass duck out of the way exactly when the kick hits, creating space and clarity in the low end. You can even nudge the spike MIDI slightly earlier to make the bass duck a millisecond before the kick hits, a trick Machine notes is similar to techniques used by artists like Daft Punk to ensure maximum impact for kick transients.

Enhancing Room Mics and Special Effects

Machine showed a killer trick for adding impact to room mics:

  1. Duplicate your mono room mic track. Let's call it "Snare Spark."
  2. Put a gate on this "Snare Spark" track, keyed by your "Snare Spike."
  3. Set the gate for a very short, sharp opening.
    This transforms the room mic into a momentary burst of energy that only occurs with the snare, adding a unique, explosive character. Even if it sounds like a short "splat" of white noise in solo, these momentary bursts can add incredible presence and cut to a snare in a dense mix, sometimes even acting as a more characterful alternative to a bottom snare mic. The beauty is you can precisely control the length of this effect using the gate's hold and release, triggered by the key spike. You might even use some EQ on this "Snare Spark" track to further shape its tonal contribution.

Phase-Accurate Sample Layering

While Machine and the band decided against layering samples on the Lamb of God drums for that particular record, he highlighted that if you were to layer drum samples, phase-accurate MIDI from key spikes is crucial. This ensures your samples align perfectly with the live drums, preventing phase issues and creating a much tighter, more powerful blend.

Tailoring Kick Sample Decay for Fast Passages

Even when using kick samples, key spikes offer advantages. For fast double kick sections, Machine puts gates on the individual left and right kick sample tracks, keyed by their respective spikes ("Kick Left Spike," "Kick Right Spike"). He then shortens the release time on the gates for these fast kicks. This tightens up the low-end, preventing muddiness and allowing each individual kick hit to be more defined, especially when the main center kick (which might have a longer, more "rock" decay) isn't playing.

Key Spike Workflow Considerations

  • It's Not Quick, It's Methodical: As Machine reiterates, this takes time to set up correctly. Don't rush the MIDI editing phase. The precision here is what makes the technique so powerful.
  • Printing MIDI vs. Keeping it Live: For instruments triggered by MIDI (like the sampler creating the spike), Machine often prefers to print them to audio. This ensures that years down the line, if you need to recall a session, you're not dependent on having the same MIDI instruments or sampler plugins. However, he also mentions that for ultimate flexibility with sample parameters (like attack, decay, sustain, release, distortion, EQ within a sampler like NI Battery), one could keep it all MIDI and process within the sampler. It's a trade-off.
  • Organization is Your Friend: Clearly label and color-code your MIDI tracks, spike audio tracks, and routing. With multiple spikes for different drum parts, a clean session is essential.

Unleash a New Level of Drum Control

MIDI key spikes offer a profound level of control over your drum dynamics and open up a wealth of creative avenues. By moving beyond traditional audio-based triggering, you can shape your drums with surgical precision, ensuring every hit performs exactly as you intend, every single time. It's a testament to how thinking outside the box can elevate your mixes from good to great.

Want to see more techniques like this and watch world-class producers like Machine mix actual songs from start to finish? At Nail The Mix, we provide you with the multitracks from massive metal songs each month and let you learn directly from the producers who mixed them. It's your chance to go beyond presets and truly unlock your sound. If you're serious about taking your metal productions to the next level, Nail The Mix is where you want to be.