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Wet mix % effect in impulse response reverb settings

PostPosted: Mon Dec 16, 2019 7:32 pm
by mnailor
Can someone please explain, or point to an explanation of, the wet mix % parameter's intended effect. This is set on the Audio Mixer window where you add impulse reverb to a bus. I can't seem to find a definition in the user guide, forum, or HW 5 info help.

This might be a related question or not: I set up intermediate buses as aux reverb mixes for each primary bus so I can direct reverb to a different stereo channel from each source channel. That works as expected -- very well. I picked St Max (church 09) to test drive it on semi-dry organs.

But when I loaded a surround organ and set the per-organ wetness slider to 0 to disable reverb processing, it sounds like the source signal is still being sent at a fairly high level by the intermediate buses, which isn't desirable since it messes up the surround channel locality and increases volume by at noticeable amount.

So, is it possible (with a single mixer preset), to get reverb added for some organs and turn off all the extra sound from the aux reverb mixes for other organs by setting the wetness slider to 0? Or will it always include some of the source (dry but not) sound?

The church 09 IR's wet mix % defaults to 37%. Would 100% remove the source/dry sound and make it all reverb?

Thank you.

Re: Wet mix % effect in impulse response reverb settings

PostPosted: Mon Dec 16, 2019 8:25 pm
by mnailor
I just realized I can use trial and error on this tomorrow when my wife isn't trying to sleep. With a stereo organ like St Annes, one pipe will sound on only one stereo channel when the aux reverb mix is completely off, otherwise a second channel will sound. This will be visually obvious on the RME TotalMix display, even if I can't hear the second pair of speakers.

I just did the experiment with amps off. It turns out that the output of the bus with reverb includes the full dry signal regardless of wet mix %. Setting the organ's wetness slider to 0 turns off the reverb, but the full dry or source signal is still sent at the same level as the source.

I could reduce the send level from the source bus to the reverb bus and increase the reverb level to compensate, but fundamentally it looks like turning off reverb at the wetness slider can't turn off the source signal coming from the reverb bus.

So sending reverb buses to different channels from the primary buses, then turning off reverb by setting the wetness slider to 0 for a wet/surround organ seemingly doesn't work in the sense of restoring the surround organ's audio outputs without duplication of the original signal to the reverb speakers. Without fiddling the levels, the reverb speakers get 100% of the source signal when the wetness slider is 0. Like quad speakers on a stereo only car radio, where the front and back are the same except for a fader.

That behavior makes perfect sense if you add reverb to a bus that is directly outputting the rank to audio channels, since wetness slider 0 restores the original source signal in full. It becomes weird when you use an aux mix for reverb to go to different speakers, and now "disabling" reverb leaves those speakers sounding the front samples identically.

I can use an Alt configs for reverb to solve this -- probably not multiple presets because I'll need to use backup/restore to keep configs in sync. So it's not a big deal. But the feature of using one preset and turning off reverb with the wetness slider for some organs does leave a doubled signal if we use separate reverb buses to separate audio. I think that applies to the examples in the user guide as well, where an aux mix adds reverb and outputs to a rear speaker pair. (That's what I'm doing, but in 8 separate audio paths.)

In case you can't tell, I really liked that idea of one preset and sliding the reverb off for organs that don't need it, but it would have to have the option to turn off the dry/source part to work here.

If anybody can see where I'm going wrong, thanks in advance!

Re: Wet mix % effect in impulse response reverb settings

PostPosted: Tue Dec 17, 2019 6:54 am
by mdyde
Hello nmailor,

I wrote a reply a few days ago that explains how the reverb wetness settings on the mixer interact with the per-organ master wetness scalar: viewtopic.php?f=1&t=17870&p=134406#p134406

mdyde wrote:
ludu wrote:I’ve a question regarding to the slider assigned to the reverb. Does it only add the reverb to the dry sound, or does it operate like a cross-fade slider, putting the dry sound gradually to zero if the value goes to 100%?


If you have reverb applied to a mixer bus then the bus's 'Wet mix %' setting determines the ratio of wet-to-dry signal that the bus outputs. Hence in that respect it's like a cross-fader between the wet signal and the dry signal.

The MIDI-controllable master 'Mixer impulse response reverb wetness scalar %' control scales the 'Wet mix %' settings for any (and all) mixer buses to which you have reverbs applied.

For example, if you have a reverb applied just to one particular mixer bus, and its 'Wet mix %' is set is to 40%, and you have the master 'Mixer impulse response reverb wetness scalar %' control set to 50% (as opposed to its default of 100%) then the effective value for that particular mixer bus's wetness would be 20%.

ludu wrote:In my current setting (using Reaper), my rear speakers give only the reverberated sound and 0% of the dry sound. Is it possible with the new mixer tool?


Absolutely. You would use one mixer bus for your reverb output, and set that bus to have the desired reverb applied, with its 'Wet mix %' setting set to 100%. There is actually a mixer bus configured by default for that purpose ( '... Mstr mix bus 4: Stereo mix 4 (aux reverb mix)' ), which receives a mix of all other primary buses by default, so that all you need to do is select a reverb for that bus and select the desired pair of audio device channels to which you want it to output its sound (i.e. the device channels to which your rear speakers are connected).


As you found, the master wetness scalar will do what people would normally want and expect (effectively giving a quick and very simple means to adjust reverb on a per-organ basis) if reverb is added directly to you main speakers.

However, if using separate dedicated reverb-only buses then reducing the master wetness scalar (e.g. to zero) won't reduce the overall level of those buses, but will instead make them output (e.g.) 100% dry signal, which I appreciate isn't what you're aiming to do. You can't currently use the master wetness scalar just to reduce the level of the wet signal without also increasing the level of the dry signal, I'm afraid. I've logged as an enhancement request that you'd like another per-organ control panel slider which behaves that way.

mnailor wrote:I can use an Alt configs for reverb to solve this -- probably not multiple presets because I'll need to use backup/restore to keep configs in sync. So it's not a big deal


The intention is/was that different mixer presets would be used for that, so you could then achieve what you want just by selecting the appropriate mixer preset for each organ. We do hope to add functionality to export/import/copy mixer presets for a future version, so as to make duplicating complex schemes quicker/easier, but there wasn't time to include that in v5.0.0, I'm afraid.

Re: Wet mix % effect in impulse response reverb settings

PostPosted: Tue Dec 17, 2019 8:39 am
by mnailor
Thanks, Martin, for explaining that. Sorry I missed your previous reply. I searched for "wet mix" and came up dry...

After looking at it more, I think using another preset will work if I just skip retyping my descriptive names for every channel and bus. I can use the names in preset one as a reference and go by numbers in preset 2. It will be difficult to put aside my need to document everything.

As you suggested, another slider that adjusts the overall output level of any buses with reverb added, including the dry component, and at 0 turns off reverb processing, with no effect on wet/dry mix %, would be a very nice addition. Or a toggle button that changes the wetness scalar from a wet/dry cross fader to a master volume for buses with reverb, if there isn't a use for both sliders simultaneously.

Even when using reverb for a dry set, turning the wetness down doesn't necessarily mean we'd want to increase the dry signal when reverb goes to separate speakers. Thank you.

Re: Wet mix % effect in impulse response reverb settings

PostPosted: Tue Dec 17, 2019 9:19 am
by mdyde
Thanks. I've added you additional thoughts to the enhancement request log.

Re: Wet mix % effect in impulse response reverb settings

PostPosted: Tue Dec 17, 2019 8:40 pm
by mnailor
Well, I just spent about 10 minutes setting up mixer preset 2 with no reverb and checking it thrice.

Preset 1 has intermediate reverb mixes and names for all the buses so I can understand the scheme.

Too easy, after all my whining above. The audio mixer is great!

Re: Wet mix % effect in impulse response reverb settings

PostPosted: Wed Dec 18, 2019 5:08 am
by mdyde
Thanks. Excellent. Glad you like it!

Re: Wet mix % effect in impulse response reverb settings

PostPosted: Thu Dec 19, 2019 8:01 pm
by mnailor
I've set up 5 presets so far, 4 with reverb on the 8 intermediate (aux reverb) buses. Each of 8 primary buses (dry or semi-dry sample) sends to 2 intermediate buses to add a front/diffuse reverb through front speakers and a rear/distant reverb through rear speakers.

I bought some IRs from SP so I have appropriate reverbs for those positions in most cases.

The duplicate dry signal output from the reverb (intermediate) buses with the organ's reverb wetness scalar slider at 0% can be reduced to inaudible as I originally was hoping. I set the reverb bus output levels to -24dB. This affects only the dry signal, while the reverb wet mix % and level dB affect the wet signal.

I always had my primary bus output levels at -6dB because OAM organs even at -24dB were too loud with 16 amps. Now I also set the interbus levels to -6dB from primary buses to intermediate buses and increased the reverb wet levels to compensate. This made the dry signal on reverb buses with wetness scalar at 0% completely inaudible to me at -30dB.

Eight independent (sources through outputs) stereo reverbs sounds much better than the one (RME UFX) or two (Lexicon 400) stereo reverbs I've tried out in the past. It's not as good as the best surround sets, but then it's not applying convolution reverb to each rank separately, while surround set ranks each have their reverb responses recorded separately.

The CPU cost of 8 reverb buses is 2 - 3 bars on the HW CPU meter for my 4 core i7. Moving to an 8 core i9 as soon as I get time (just unpacked the box so far) makes that not a big concern for me.

I couldn't be more pleased with the way this works so far. I now have a Mt. Carmel Skinner I actually enjoy playing, with truncated releases and some Caen IRs added. Little Waldingfield sounds lively in Chapel 01. I moved Brescia to Izola. Very fun, if a little tacky...