Feedback send/return

From Fractal Audio Systems Wiki
Jump to: navigation, search

The Feedback Send and Return blocks allow you to feedback sound from one point in the routing to any other point.

The Send block has no parameters, while the Return block has a basic mixer. Adjust the MIX control to set the ratio of direct and feedback signals.

Best results are achieved when feeding back a pure delayed signal. If any direct signal is fed back the resulting loop will usually be unstable and/or sound strange due to phase cancellation.

Warning: Use caution with the Feedback blocks as you can easily program an unstable loop and cause internal clipping of the signal and/or very high sound levels which can damage your hearing. Always start with the MIX control on zero and slowly bring it up. If you start to hear squealing or other signs of instability return the MIX control to zero and analyze your routing for possible causes of instability.


Extending an effects chain

The Feedback Send and Return blocks can be used to extend the signal chain beyond the standard 12 blocks.

It's very straightforward. You begin a serial signal chain at the first block in a row and continue it to the next-to-last block in the same row. In that block, place the feedback send. If you try to place the feedback send in the final block, it will automatically be connected to the output, which you do not want.

Now, begin another row on the next-to-first block by placing the feedback return there, and continue this second row all the way to the output. If you try to use the first block in the row, the return will automatically be connected to the input, which you also do not want. This makes possible a total of up to 20 blocks in series.

Feedback.JPG

You can actually squeeze in one more block on top if you put the Feedback Send in the last column and turn that row's LEVEL down in the Output mixer. You can cram another into the second row by putting the Feedback Return in the first column, seting the mix level to 100% and bypass mode to mute out. That gives you 22 usable series blocks.

Inserting effects in a Delay loop

It is possible with the Axe-Fx to insert effects into the loop of a Delay block. The Feedback blocks need to be used, in conjunction with some unusual routing.

Effect on dry signal

To have the effect present on the dry signal as well as the Delay tail:

  • Place the desired effect block in the chain where you want it, and the the Delay, to be. Connect it to the effect(s) before and after it in the chain.
  • Configure the effect however you want it to behave.
  • In the next row and next column, insert a Delay block and connect it to the output of the effect block you just placed.
  • Set the Delay INGAIN to 100% and the MIX to 100% wet.
  • Set FEEDBACK to zero. (This would be internal, "dry" echo.)
  • Configure the time TIME and other parameters as you normally would.
  • Attach the Feedback Send block to the output of the Delay.
  • Place the Feedback Return block in the column prior to the effect block from the first step and connect it to the input of that effect.
  • Set the Feedback Return's MIX to 100%.
  • The Feedback Return's LEVEL control now acts as a feedback control for the effected delay loop. Higher levels mean more trips through the effect.

Feedback Delay effect.gif

It is possible to extend this technique to multiple effects in the loop by simply adding more effects to the chain between where the Feedback Return injects the delayed signal back in and where the Delay block gets its input.

Effect on delay tail only

To have the effect present on the Delay tail, but not on the dry signal, use the approach above, but put the effect in the parallel branch in front of the Delay as shown here: Feedback Delay effect 2.gif

Effect on delay tail only, with one clean echo

To have the effect present on the Delay tail, but not on the first echo (nor on the dry signal), use the approach above, but put the effect in the parallel branch after the Delay and connect to the Delay as the input instead of the effect block, as shown here: Feedback Delay effect 3.gif