Feedback Rack

A feedback machine built as an Audio Effect Rack: four parallel chains that each regenerate in their own way (Echo with its feedback cranked, Hybrid Reverb feeding itself, Roar’s Feedback routing with pitch, Corpus ringing), a Limiter on every chain and on the rack output so nothing ever reaches the PA above −3 dBFS, and an Envelope Follower that turns the feedback down automatically when it gets loud. Six macros: Feedback, Pitch, Filter, Chaos, Freeze, Safety. Lives on a Return track that sends to itself, which is the only way in Live to get true feedback around a device chain rather than inside one device. Use it for dub delay throws, no-input-mixer style drones, industrial techno noise beds, ambient infinite tails and the point in a live set where you want the room to lean forward.

Layout

How it's built

1. Create a Return track (Cmd+Alt+T) and name it "FB". In Preferences → Record/Warp/Launch nothing is needed, but in the Mixer, right-click the FB return’s send knob and enable the send to itself (Live shows return sends in the return track’s own send section; the FB → FB send is disabled by default, click "Enable" in the context menu). Set it to −inf for now.
2. On the FB return add an empty Audio Effect Rack. Four chains, all full-range, no zoning: Audio Effect Rack chains run in parallel and sum.
3. Chain "Echo Loop": Echo in Stereo mode, Left 1/4 dotted, Right 3/16, feedback 85%, Filter on: HP 200 Hz, LP 4 kHz, Modulation rate 0.3 Hz amount 20%, Noise 10%, Wobble 0, Reverb 20% (Echo’s internal reverb after the loop), dry/wet 100%. Then Auto Filter LP 12 dB at 3 kHz with its Envelope follower section set to −30% so loud input closes the filter. Then Limiter, ceiling −6 dB, release 1 ms? No: release 100 ms, lookahead 1.5 ms. Chain volume −6 dB.
4. Chain "Reverb Loop": Hybrid Reverb, algorithm Dark Hall, decay 20 s, size 100%, pre-delay 20 ms, low cut 150 Hz, high damping 6 kHz, dry/wet 100%, Convolution off (algorithm only, cheaper and freezes cleanly). Then Shifter in Pitch mode +7 st, dry/wet 30%, so every pass up the loop gets a fifth added, which spirals. Then Limiter −6 dB. Chain volume −9 dB.
5. Chain "Roar Loop": Roar, routing Feedback. Stage 1 Soft Sine, Drive 6 dB, Tone 50%. Feedback section: amount 60%, Pitch 0 st, Time 25 ms (so the feedback path is a short comb, i.e. a resonant pitch at 40 Hz; Pitch macro moves it), feedback filter LP 5 kHz. Post-filter LP at 10 kHz. Dry/wet 100%. Then Limiter −6 dB. Chain volume −8 dB.
6. Chain "Corpus Loop": Corpus, resonator type String, Decay 90%, Material 40%, Tune C2 with Fine 0, Brightness 60%, Inharmonics 0, LP filter 4 kHz, Width 80%, dry/wet 100%, Off Decay off. Then Saturator Soft Sine 3 dB, then Limiter −6 dB. Chain volume −10 dB.
7. After the rack, on the FB return: Utility (gain 0, for the Safety macro) and a second Limiter, ceiling −3 dB, release 50 ms, lookahead 3 ms. This limiter is not optional. The self-send loop can go unstable within one bar and a Limiter is the only thing between you and a blown tweeter.
8. Before the rack, add an Envelope Follower (Max for Live audio effect). Gain 0 dB, Rise 10 ms, Fall 400 ms. Map its output to the rack’s Feedback macro with depth −100%: loud input pulls Feedback down. The Safety macro scales this depth.
9. Select the Envelope Follower, Audio Effect Rack, Utility and Limiter together and group them (Cmd+G) into an outer rack so macros can reach the Utility and the output Limiter. Map macros on the outer rack.
10. Feedback: Echo feedback 30 → 110% (Echo allows over 100%; that is the runaway region), Hybrid Reverb decay 2 → 60 s, Roar feedback 20 → 95%, Corpus decay 40 → 100%. Also MIDI-map the FB return’s own send to the same controller as this macro (macros cannot map mixer sends; use a MIDI mapping of the physical knob to both the macro and the send, send range −inf → −6 dB).
11. Pitch: Roar feedback pitch −12 → +12 st, Shifter pitch −12 → +12 st, Corpus tune −12 → +12 st. Centre = unison.
12. Filter: Echo filter LP 800 Hz → 12 kHz, Auto Filter freq 400 Hz → 8 kHz, Corpus LP 800 Hz → 10 kHz, Roar post-filter 500 Hz → 10 kHz. Lowering Filter is the first thing that tames a screaming loop; it should be under your hand always.
13. Chaos: Echo modulation amount 0 → 100%, Echo wobble 0 → 60%, Roar LFO → feedback pitch 0 → 40% (add an LFO in Roar’s mod matrix targeting feedback pitch, rate 0.2 Hz), Corpus material 0 → 100%.
14. Freeze: Hybrid Reverb Freeze off → on (switch mapping, half-way point), plus small second mappings: Echo feedback +20% and Corpus decay +10% so the freeze is a hold across all chains, not only the reverb.
15. Safety: output Limiter ceiling −1 → −12 dB, Envelope Follower depth 0 → −100% (map the Envelope Follower’s depth parameter), Utility gain 0 → −18 dB. Turn Safety up and the rack gets quieter and more self-regulating. Default 60.
16. Macro Variations: "Dub throw" (Feedback 45, Pitch 64, Filter 50, Chaos 20, Freeze 0, Safety 50), "Drone" (Feedback 85, Pitch 70, Filter 35, Chaos 10, Freeze 127, Safety 70), "Runaway" (Feedback 127, Pitch 64, Filter 70, Chaos 80, Freeze 0, Safety 100). Exclude Safety and Feedback from randomization. Always.

Macro map

Signal flow notes

The self-send return routing

Live blocks a return from sending to itself by default. Enable it from the send knob’s context menu on the return track. The loop then runs: FB return output → its own send → FB return input, with one buffer of latency (so at 128 samples / 48 kHz about 2.7 ms, plus device latency). That latency is the loop’s own comb pitch: at 2.7 ms you get a resonance near 370 Hz, which is why the loop "sings" at a fixed note when the Echo and Reverb are bypassed. Roar’s Feedback time at 25 ms sits well below that and gives a separate, tunable 40 Hz resonance.

Start with the self-send at −inf. Bring it up slowly; the point where the Limiter starts working continuously is the edge. Most of the musical range is between −18 and −8 dB on the send. Above −6 dB you are relying entirely on the Safety chain, and the sound becomes a steady tone rather than a decaying echo.

Variations

• Dub delay return: keep only Echo Loop and Reverb Loop, Pitch fixed at 64, Shifter off, Safety 40, Filter as the main performance knob, self-send around −14 dB. See dub delay send rack, dub FX and dub reggae.
• No-input drone: no external send at all. Enable the self-send, set Feedback 100, Chaos 30, let Echo Noise (10%) seed the loop, and play Pitch and Filter. This is the no-input-mixer technique inside Live. See no-input feedback.
• Industrial techno bed: Roar Loop and Corpus Loop only, Roar shaper Hard, Corpus type Tube, Feedback 90, Safety 80, Filter 30, sidechain the Utility from the kick with a Compressor in front. See industrial techno.
• Ambient infinite tail: Reverb Loop at −3 dB, others at −20 dB, Freeze as the only gesture, Shifter +12 st at 15% for a slow octave bloom, Safety 90. See ambient.
• Modular hybrid: replace the Roar Loop with an External Audio Effect sending to a eurorack filter or wavefolder and back; the hardware latency becomes part of the loop pitch, which is its own instrument. See modular hybrid rack.

Performance notes

• Push: Feedback on encoder 1, Filter on encoder 2, Freeze on a pad, Safety on encoder 8 where you will not bump it. Keep the FB return’s send on a physical fader with a MIDI map, not on an encoder; a fader has a visible position you can slam to zero.
• The kill move: map one button to a Macro Variation "Off" (Feedback 0, Freeze 0, Safety 127). Practise hitting it. Recalling a variation is instant; drawing a knob down is not.
• Automation vs macro: nothing in this rack should be automated except Filter in a planned breakdown. Feedback and Freeze are performed with a hand on Safety.
• Throws: use clip envelopes on the source tracks’ send-to-FB amounts for repeatable throws; keep the self-send steady and let the rack do the regeneration.
• CPU: Hybrid Reverb and Corpus are the cost, maybe 8% of a core. The Envelope Follower is negligible. The return runs permanently, so freeze is not possible; keep this rack on one return only.
• Ears: the loop reaches the limiter ceiling at a constant −3 dBFS when it runs away. That is not loud on a meter, but a steady 370 Hz tone at −3 dBFS for 30 seconds is unpleasant on a system. Use Safety.

Related

• No-input feedback · Dub FX and delays · Drones
• Routing and resampling · Roar and saturation · Modulation and Max for Live
• Delay design · Reverb and space · Loudness and limiting · Performance and live
• Dub delay send rack · Texture rack · Modular hybrid rack
• Dub techno · Industrial techno