Reaper: Make Any EQ Dynamic

Reaper might not have a dedicated dynamic EQ, but it can turn any EQ into one that’s more powerful than most third‑party tools!

Increasing the track’s channel count to 4 (left), and adding a ‘receive’ from the hi‑hats to the track’s internal channels 3+4Dynamic EQ can be a great tool for tackling various problems, including where one sound masks another intermittently, causing the tone to change and making parts difficult to ‘sit’ in a mix. In such situations, a static EQ can mean tonal compromise, and while you can use automation, this is very fiddly to do manually, particularly if you need to refine the automation later.

You might have noticed that Reaper doesn’t have a dedicated dynamic EQ. But that’s because it doesn’t really need one! Not only are there are plenty of capable third‑party plug‑ins (including the freeware TDR Nova), but Reaper has the power to make any EQ dynamic. What’s more, you can use any signal in your project as a side‑chain trigger, and even trigger different bands in the same EQ plug‑in from different signals! Below, I’ll take you some examples.

Ducked Reverb With ReaEQ?

I’ll start with one from a recent project. I had a bright‑sounding reverb (a Lexicon 224 emulation) on one track and loved what it added to the percussion‑and‑marimba intro. When the hi‑hats came in, though, there was too much top‑end ‘sizzle’. So I decided to duck some of the reverb track’s high frequencies only when there was a hat hit. Similarly, I wanted to duck some of the reverb’s low frequencies when a synth bass played.

I placed an instance of ReaEQ on the reverb track and identified the first frequency range I wished to cut in the reverb (around 4kHz). I set ReaEQ’s frequency and bandwidth on a ReaEQ Band filter. Then I set up the routing to ensure the gain of this band would react to the hi‑hat: I added two more channels on the reverb track by clicking on ‘2 in+out’ (top right of ReaEQ window), and increased the track channels to 4. By the way, this Reaper track channels feature has plenty of uses — check out Matt Houghton’s SOS October 2023 Reaper workshop for more examples.

Using an audio signal to modulate parameters on ReaEQ.The next step was to send audio from the hi‑hat track to the reverb track’s channels 3+4. There are multiple ways to do this, but the easiest approach is a simple drag/drop. In the main window’s Track Control Panel Drag, you can drag from the hi‑hat track’s routing button on to the reverb track. A pop‑up appears, and you can select the destination (channels 3+4 on the reverb). Alternatively, in the mixer, drag from the routing button or any send slot onto the reverb track; the same routing dialogue pops up.

To make ReaEQ react to this side‑chain signal, I turned to Reaper’s powerful Parameter Modulation feature: I clicked on the EQ band’s gain slider, then clicked the ‘Param’ button and selected ‘Parameter modulation/MIDI link.’ In the window that popped up, I chose ‘Audio control signal (side‑chain)’, then set ‘Track audio channel’ to ‘3+4’. With ReaEQ now receiving the trigger signal, I set the EQ up to duck as follows:

• Ensured the top slider was at its default midpoint. This makes the gain 0dB when the control signal is below the threshold.
• Pulled the ‘Min volume’ slider down below the level on the input meter above. At this point, a green‑bordered rectangle appears in the ‘Audio control signal shaping’ window.
• Set the Direction to ‘negative’, to trigger a cut (set to positive if you want...