Reaper: Feedback Loops

To prevent nasty accidents, feedback loops aren’t enabled by default: you can allow them in the Project Settings / Advanced tab.

In allowing you to create feedback loops, Reaper gives you access to a world of creative effects.

The humble feedback loop, where a portion of the output from an effects chain is fed back to its input, has been used and abused to creative effect by musicians and engineers for decades. But while it’s not uncommon to find feedback controls on individual plug‑ins (not least delays), and although it’s easy to set up feedback loops on longer chains using a traditional mixing console, DAWs often tend either to prohibit their use or make setting them up fiddly. Arguably, they do that for good reasons, the main one being that it’s easy to create a signal path that results in a ‘howl‑round’ effect, whereby the signal keeps escalating in level rather like when a mic picks up its own signal from a PA speaker. It’s a phenomenon that can not only be annoying but one which also has the potential to send ear‑splitting or tweeter‑frying levels out of your interface!

Unsurprisingly, then, Reaper’s default setting is to disable feedback loops, but it can be set up to allow them and to do that all you need do is tick a box: in the Project Settings window, go to the Advanced tab and tick the option to ‘Allow feedback in routing (can result in lower performance, louder noises)’. Hit OK and you’re free to start experimenting. Really, though, there are a few things you should know before you do that! In this article, I’ll explain a routing setup that will allow you to experiment with feedback loops in Reaper, safe in the knowledge you won’t fall into the howl‑round trap. I’ll also run through some creative options made possible by feedback loops, using Reaper’s own plug‑ins and some third‑party ones, which might open up less obvious avenues for exploration.

Routing Setup

Start by creating three blank tracks, which for now I’ll call Tracks 1, 2 and 3 (we’ll assign meaningful names below). Next you must set up some sends/receives to shunt the signal between these tracks. Open the Routing dialogue for Track 2, then set up a unity‑gain Receive from Track 1 and a unity‑gain Send to Track 3. Then open the Routing window for Track 3, untick the Master Send box (this is important!) and also create a unity‑gain Send back to Track 2. I’m assuming we’re dealing with regular two‑channel stereo tracks here, by the way.

The basic routing setup for a feedback loop in Reaper.

In case you’ve not clocked what you’ve just done, Track 1, which I’ve called Source in the screenshots, is the one you’ll use for your incoming signal — ie. whatever instrument/sound/sample you’re playing/recording and want to treat with this effect. Track 2 I’ve called Effect, since this is the effect to which you’re sending the source signal. This is routed...