"It's less complicated than it might seem at the first glance..." 

... for Dietz. His mind is wrapped around this fully (I heard he took the Ambisonics processing treatment himself).

But I am still trying to figure it out  - this is related to my incomplete thread about "pure" MIR.

Are these correct statements? 

1) The "Dry" is the input signal processed for positioning, EQ, etc. but has no audible reverberation from the hall.

2) The "Wet" is the input signal that has gone through the processing to make it resemble what the impulse did when reverberating in the hall, and is purely the reverberation of the hall with the positioning characteristics of an impulse in that specific spot (which distinguishes it from a hardware reverb that just slathers the same reverb over everything and uses the dry signal to establish positioning).

3) The mix of the two on an individual instrument is somewhat similar to a hardware reverb mix of dry/wet though each component is far more processed to begin with.

I have some questions too about what specifically is contained in the mirpro dry signal.  What specifically is being done there to mimic the spatial location?  Is the "depth" taken into consideration in terms of delay to the virtual mic array?  Or is it just applying the profile EQ, pan and width?  The further away a mic is from a mic, the more that lows and highs are rolled off...does MirPro do this to the dry signal depending on the location of the icon in the room relative to the mic array?  is the sound delayed, per the distance?  What if you are using more then one mic array at different distances?

It seems like it would be a little advantageous to have early reflections isolated from the rest of the reflections.. in order to help with spatial positioning yet still allowing us to dial in how much of the later complex reflections we want in the mix.  But if i am understanding correctly, ER's are in the "wet" component, along with all the longer reflections.  Do I have that right?

Interesting questions! It will take some time to answer them thoroughly, though, so please allow for little delay until tomorrow. Thanks for your patience!

Here we go! 😊

@Another User said:

I presume that if I wanted to combine the room sound of mirpro with a close mic sound, I would need to split off the totally bypassed dry sound in the daw or vep before it hits mirpro and handle it as I wish through other plugins, while mirpro would always produce a mix for the instrument that is effected with instrument profile eq, pan, width (dry) mixed with all the room reflections (wet). Note that if I were trying to do this i would probably want wet set to 100% to avoid phase problems between the close mic and the spatially dry signal of mirpro.

This would be a screnario where you would (ab)use MIR as some kind of glorified AUX-send based reverb engine. You would have to set MIR to 100% wet. - There are rare occasions where this might make sense in an artistic way of doing things (... mixing drums for a typical pop music track comes to mind), and in these cases your approach makes sense. Don't expect anything close to the realism MIR is able to achieve when used "properly", though. 😉

@Another User said:

and that any setting other then 50% is basically to isolate more of the spatially dry or more of the reflected room, in a way that couldn’t be done in real life but still might be useful?

The answer is: "Yes, as long as you don't misunderstand "Real Life" as a single value".😊  The default values are more like an approximation to a "believable" acoustic impression of a hall. Deviations from this default value can make sense to a surprisingly large degree.

HTH,

Hi William!

@Another User said:

3) The mix of the two on an individual instrument is somewhat similar to a hardware reverb mix of dry/wet though each component is far more processed to begin with.

Yes, but please keep in mind that the Dry/Direct signal component in MIR Pro is already processed, too (unlike in case of your typical reverb engine, which will leave the source signal untouched (hopefully!)).

@Another User said:

in order to help with spatial positioning yet still allowing us to dial in how much of the later complex reflections we want in the mix.  But if i am understanding correctly, ER's are in the "wet" component, along with all the longer reflections.  Do I have that right?

Yes, exactly.

That is a great reply, thanks for that info Dietz.  

Alright, reading through some old posts on this forum...I think I have come to the following understanding about the mir-positioned dry signal (please correct errors):

1. Its been stated that the dry signal should be thought of like a close spot mic.  In the real world, a close mic does not have distance information in the signal, nor panning, etc..  so its a bit different then a close mic in that regard I think?
2. If Air absorption is checked, then a hi shelf EQ will be applied to the dry signal to simulate the air dampening some high frequency, increasingly based on distance to the main mic.
3. If distance dependent scaling is checked, then distance from the main mic determines the level also, for sure to the dry signal, not sure if this effects the wet level also, I think maybe so, the IR's will pick up the sound from the instrument, based on the instrument profile and directivity profile and its position in the room will matter a lot in terms of what ends up at the main mic.
4. If directivity filtering is on, then the direction of the player's nose can effect many aspects of the sound (how the sound will be effected exactly is unknown to us other then through trial and error), including level and maybe EQ?  The directivity profile is always effecting the wet signal, but it only effects the dry signal if this box is checked.
5. Each instrument can have a character profile that applies some factory black-box EQ...the exact curves unknown to us.  The character profile uses the instrument profile in some way, and does lots of "magic stuff".
6. Dry/wet slider for each instrument adjusts the level of the close spot mic dry signal, which also happens to have some of the other elements mentioned above, which infer distance from the main mic, even though a real world close mic would not have that distance information.  The wet signal includes the entire room, and stuff like air absorption, directivity, etc..would inherently be in the room IR's, which the wet/dry slider can be used to suit taste.

So more questions..

1. is LR panning contained in the mir-positioned dry signal (unlike a real world close mic) or is it expected that we pan the channel in the mixer (like we would with a real world close mic)
2. In Mike Verta's masterclass on orchestral in the box mixing, he talks about needing a low-shelf also to emulate distance from the main mic.  Mike Verta in his videos did an example with and without this rolloff, feeding into a typical convolution reverb.  The one without the low shelf sounded like a PA speaker at the end of the hall and the one with the shelf sounded more natural.  His claim is that with increased distance, some low frequency is lost over distance.  So if you're trying to place some instruments back in the mix, in terms of depth or distance from the audience, then using a low-shelf seems to be his solution.  In his videos where he demonstrated with and without that low-shelf, the differerence was very clear to me.  What does MIR do in this regard?  I notice there is a black-box "Distance" character profile, which might be doing that with "magic", but its unclear.  Also does the icon distance from the main mic effect how much the low end would be rolled off (less proximity effect).  What can you say about this topic or how MirPro handles it in the dry signal?  The wet signal will presumably have that taken care of by the IR's.

That's all I have for now.  My conclusion is that the mir-postitioned dry signal is not really emulating a real world close spot mic.  I understand why you're kind of thinking about it that way, but since there is the possibility to pan it, air absorb it, distance scale it, directivity filter it...and possibly the low end is being shelved off based on the icon position too, I'm not sure..  well then its not really a close mic after all...other then the time alignment that is being done to make sure we don't have phasing problems.    Am I understanding correctly at this point?

Hi Dewdman,

You keep me busy! 😄

@Another User said:

I understand why you're kind of thinking about it that way, but since there is the possibility to pan it, air absorb it, distance scale it, directivity filter it...and possibly the low end is being shelved off based on the icon position too, I'm not sure..  well then its not really a close mic after all...other then the time alignment that is being done to make sure we don't have phasing problems.    Am I understanding correctly at this point?

I think so. Enjoy MIR Pro!

Kind regards,

Dietz, those eq curves are very helpful thank you!  When I load Teldex, I see another character profile show up sometimes called MIRX Teldex.  Any clue about that one?

Ultimately I can always put my own eq in front of mirpro in order to eliminate a closely mic’d proximity warmth from a sound that is meant to be further back. I just wanted to have a clear idea what MIR Pro is doing to the dry signal based on distance. Looks like in a generic way the distance character profile would also provide a bit of a one size fits all low shelf to imply some distance that way. I will play with that.

By the way I wasn’t meaning to infer anything “bad” about calling the dry signal the "close mic". Just seeking absolute clarity about what is in that signal; and for the moment trying to be absolutely literal about what a close mic would have in the signal vs what MIR Pro potentially has in the dry signal.

So it’s a close mic signal after a mix engineer has potentially tweaked the sound in certain ways. Maybe a good way to think about it is: it’s a close mic after an engineer has panned it, eq’d it for character, adjusted the level and eq to mimic distance and air absorption (but not removing proximity effect unless distance character profile is used but still that is not variable based on icon position), and accounting for either the mic being attached to the players nose or being attached to the floor. That’s a mouthful though I get it.

Regarding proximity effect that may be baked into samples, that will always depend a lot on the samples being used. Many sample libraries have been close mic’d and are very present front and center. When they are lathered with reverb they will sound wrong. Our brain is hearing both proximity and reverb and it doesn’t compute. So that’s why there can often be a need to low shelf the low end in addition to hi end.  But it will always depend on the source samples being used, how they were produced to begin with...the mics, distances and processing on those source samples are all part of the close mic signal chain.

I don’t hear a lot of proximity warmth when I test out MIR Pro with various vsl instruments, which is probably a good thing most of the time. If vsl shelved out the proximity from the close mic samples to begin with then it’s a non issue when using them in MIR Pro unless you specifically wanted to hear the proximity. Other libraries, however might need more shelving and I am wondering about whether low shelf would need to be adjustable to account for the desired depth of the instrument, or distance from the main mic. Verta calls it z-plane.  It would have been cool if the icon on the soundstage effected this aspect of distance also in the dry signal. 

Perhaps if VSL had provided two parallel sets of IR's, one for the dry signal and one for the wet signal (rather then just removing the Dry from the IR's), then the IR's themselves I guess might have captured that.  But since dry has been removed from the wet IR's...then we have to mix certain assumptions about distance back in using conventional mixing techinques such as EQ.

@Another User said:

Perhaps if VSL had provided two parallel sets of IR's, one for the dry signal and one for the wet signal (rather then just removing the Dry from the IR's) [...]

Like pointed out before: This could be done in simple stereo convolution reverbs*), but not in case of MIR, where we mix and match more than 100 individual IRs for a single stereo source. Severe phasing issues and ugly colouring would be the result.

You know the proverb: "You can't have your cake and eat it." 😉

*) ... where it still sounds bad more often than not

I'm aware of Mirx Mode, but not the character profile by that name when I'm not even using Mirx Mode.  What is that doing?

I was not meaning to infer that we should bypass MirPro and do things the manual way, there is no point in purchasing MirPro if that is case obviously...Still trying to get confirmation that I understand what MirPro is doing to the dry signal?  It does sound like, however, I will probably want to think about using EQ and other plugins pre and post MIRPRo in order ot handle z-plane oriented spatiality which MIR Pro is currently NOT handling on the dry signal, mainly proximity effect.

My hypothetical point about parallel IR's, is not what you were understanding from my words I don't think, but we don't need to cover that I was just fantacizing out loud and it has distracted you from my core questions.  

@Another User said:

It does sound like, however, I will probably want to think about using EQ and other plugins pre and post MIRPRo in order ot handle z-plane oriented spatiality which MIR Pro is currently NOT handling on the dry signal, mainly proximity effect.

If it sounds right for you, then there's nothing wrong about that! 😊 I use track- and bus-based processing in MIR centered mixes as much as I do in "conventional" ones.

@Another User said:

Still trying to get confirmation that I understand what MirPro is doing to the dry signal? 

Let me try to summarize and if you can just confirm accuracy mainly regarding the dry signal...

1. The original dry signal that came into MIR is never passed through in any fashion.  MIR blocks it and replaces it with the "MIR-positioned dry" signal.
2. The wet signal has had the direct instrument sound to the main mics specfically cut out.  But otherwise it has all reflections happening in the room, early and late..as encoded in the IR's, but with the direct sound from the instruments missing.
3. MIRPro modifies the incoming signal, which is assumed to be a center panned signal; and effects the signal to provide spatial information, the result is the MIR-positioned dry signal
4. The wet/dry slider can be used to adjust the balance between the MIR-positioned dry signal and the wet signal, described above.
5. The MIR-positioned dry signal has been time aligned with the wet signal to avoid any phasing problems that are typical in real world recording situations.
6. The dry signal is regarded like a close spot mike, but after a mixing engineer has applied a few more typical adjustments to that close mic dry signal, resulting in a stereo MIR-positioned dry signal.  The following options are available for the dry signal:
7. The directivity filter option will determine whether the direction of the player icon will have any bearing on the dry sound.  If checked, then it will be considered like the mic is planted to the floor, and directivity profile will be used to effect various aspects of the sound such as level, EQ, etc..based on directivity profile.  If unchecked, then the direction the player is facing has no bearing on the dry sound, only to the wet sound.
8. Distance depedent scaling, if checked, will take into consideration the distance from the player to the main mic and adjust the LEVEL accordingly in the dry signal.
9. Air Absorption, if checked, will roll off HF from the dry signal, based on distance from the player to the main mic.
10. Proximity effect is not adjusted automatically by icon placement on the stage, however there is a character profile called "Distance" that can be used to specifically remove proximity warmth in order to place an instrument futher towards the back of the stage, somewhat generically, in terms of proximity warmth. 
11. LR pan of the instrument is determined by the icon location on the stage relative to the main mic.  The dry (and wet) output of MIRPro will be stereo, panned signal
12. The width of the instrument or ensemble will also be determined from the icon and will effect the dry signal in the stereo panned output in some way.
13. Instrument and character profiles provide a few typical default EQ curves (and 2100 other settings), in order to get a slightly different engineered sound out of the instrument.  The ones built for MIRx mode are of interest because they have been crafted to make VSL instruments sound great in specific VSL rooms.  These will effect both the dry and wet signals.

If that is all correct as stated, then that about covers it I think.  My overall impression is that the wet signal will generally just take care of itself, it has all the widths, sizes, distances, panning, directivity, reflections and everything else that actually happened in the room...all present in the IR's...  so the wet signal will have all that, but will sound kind of wet because the direct sound to the main mic from all the instruments has been cut out.  You can play around with different mic arrays to hear more or less of the later reflections or to change the stereo width of the wet sound.  Or adjust the dry/wet slider or reverberation time to taste.

Then we mix the above mentioned MIR-positioned dry signal in with the wet using the wet/dry slider...which has had some of the spatial information engineered back into it, such as panning and directivity, but might not be a complete picture of the actual distance to the main mic in terms of proximity EQ.  We lost that when we removed the direct signal from the main mic.  Its ok, it just means a pre or post EQ may be useful to dial that in exactly if the character profiles aren't enough of a fix.

Sorry for the slightly delayed reply, Dewdman. I'm in the midst of a quite demanding recording session ATM, which leaves little spare time for forum discussions. 

@Another User said:

If that is all correct as stated, then that about covers it I think. [...]

*two thumbs up* 😊

This whole thread was incredibly useful!  Thank you Dietz and Dewdman.