FX: Monitoring - where exactly is it located in Reaper's signal path?

Happy New Year to all! I'm trying to understand where in the signal flow the "FX: Monitoring" chain is located. My audio interface disposes of 128 hardware outputs and I'm using Reaper default outs 1-2 as my main stereo out for monioring. The following HW stereo outputs are also used to send various signals and busses to dedicated channels on my monitoring console (cue mixes, sends to HW effects, multiple stereo stems for analog summing). I never used the "FX: Monitoring" feature before. I just tried it now and put ReaEQ into the "FX: Monitoring" chain, then played back a music file from a track with default routing via the master and Reaper's main stereo out wasn't affected by the low-cut I had dialed in. I then unchecked the track's "Master send" and instead added a HW send to the same output 1-2 to it and now I could hear the low-cut. I don't understand the logic behind this. Maybe someone could come up with a simple signal flow chart where it's easy to see where the "FX: Monitoring" effects are located in the signal path and whether the path can be adjusted or mofified by the user. "FX: Monitoring" is not shown in the Reaper signal flow charts I could find on the internet. Any clarification would be much appreciated. .

To me this seems easy: the Monitor FX is fed by the output sstreams of the Master track and fed to the first (count of channels in the Monitor FX) "Output Range" output channels of the audio interface.

FX: Monitoring is applied to the signal just before it reaches the designated monitoring hardware outputs (like 1-2). It does not process signals routed to other hardware outputs or affect renders. It is designed for room correction, monitoring-specific processing, or headphone mixes. As it is independent of the Master FX chain, it only applies to signals routed to the designated monitoring outputs. Monitoring means listening to tracks, plus any Master FX chain (if any), while rendering means capturing the signal being recorded, which does not pass through the FX Monitoring chain. Therefore, when you render online, what you hear might differ from what is sent to disk, as you hear the FX Monitoring chain, but it is not included in the data being rendered.

1. Setting Monitoring Outputs: - Monitoring outputs set in the I/O panel of track. - These differ from the ASIO tab for general audio routing. - If no specific outputs set, default ASIO output (1-2) used. - FX Monitoring applies only to designated outputs. - FX chain must be placed in FX Monitoring to hear difference. 2. Master Send & Direct Routing: - When Master send is enabled, signal routed through Master Bus. - It passes through FX Monitoring chain, affecting output. - If Master send unchecked and direct hardware send used, signal bypasses Master Bus and FX but still passes FX chain. 3. Monitoring vs. Rendering: - FX Monitoring applies to signal routed to monitoring outputs. - Rendering captures signal post-Master FX without FX Monitoring. - What you hear may differ from rendered output, no FX. 4. No Master Send: - If Master send unchecked and rendered, signal routed direct. - It bypasses Master Bus and Master FX, excluding those FX. - Rendered signal only includes direct routing effects. 5. FX Monitoring with ASIO Output vs FX Monitoring Output: - FX Monitoring output gives processed signal to designated out. - ASIO output settings handle general audio routing. - When both are set, you hear ASIO and processed FX output.

Thanks a lot for the effort F1308! Much appreciated! 1. I still think that a simple signal flow chart will tell more than a thousand words and we absolutely need it for quick reference and easy understanding. For anyone familiar and experienced with this topic, it should be easy to create such a chart. 2. How do I specify that the HW output I add to a track or to the master track will be a dedicated monitoring output? They all look like regular HW outputs in my drop-down list and none of them has an indicator that it will act as a monitoring output. 3. Could I specify multiple monitoring outputs for different purposes and with different properties? If yes, how would I do this? 4. Where did you find all this information in the first place?? This essential information should be in the manual or at a location that is easy to find! Every Reaper user must know how this works! The info given is still very fragmentary/incomplete to get the user started (me at least). .

Well, I was under a tree one day, and an apple fell, so I started thinking... If only Reaper had this info clearly laid out! But once I started digging, it all made sense. Sometimes the answers just fall into place, but they’re not always easy to find in the documentation.

After pressing the Route button, or via right-click on the volume fader, you are offered the option to Add new hardware output. Among the available outputs, select the one you want to use for moitoring. Once selected, the track will be sent to both the ASIO output and any newly added outputs, but this is for monitoring purposes only, not for rendering. This ensures the audio is routed to the monitoring output, where any FX monitoring chains can be applied, without affecting the final rendered file.

I also use the Monitoring FX for any visual analysers, so they don't take any CPU when rendering.

from Reaper's manual: ----------- 6.13 Hardware Output FX Monitoring To open the FX: Monitoring window use the View, Monitoring FX command from the main menu, or hold Shift while clicking the FX button of the Master track. You can specify any FX that you want to put on your hardware outputs. These do not show up in renders, do not affect the metronome and are not stored in the project file. You might use this feature, for example, to run analysis FX, or to compensate for the acoustic characteristics of a particular room. Within the FX:Monitoring window, click on the Param button then Learn to assign control of any selected FX parameter to an external control device. ------------ There's not much but a simple diagram can be this Reaper's Master fader -> Monitor FX -> Hardware outputs there's multiple ways to use it: I use it mainly for Sonarworks room correction software BUT you can add more outputs and use a vst monitor controller, or correct multiple outputs for tuning a surround system. You can put a limiter or a mastering chain that you don't want to print while render but you just wanna listen for referencing It's fixed and does not change when changing sessions

to be clear, if you have monitoring FX on, then the hardware outputs are virtualized and routed through these monitoring FX. So it always goes "track hardware output" -> monitor FX (if channel within the monitor FX count, otherwise passthru) -> real hardware output. the master track is like any other track, it has its own hardware outputs, etc (though the master track hardware outputs are always post-fader).