I have a track that's playing a very clean NI Razor synth that usually sounds great. However, when I set the master bus to interleave = mono, this synth distorts like crazy. Nothing is even close to clipping. What could be causing this? 

Hmmm... a bit of a long shot, but could it be summing the left and right channels in the master bus?

I don't have the synth mentioned, but I have seen issues like this with certain effects that are meant for stereo use and work fine that way, but give nasty issues of one for or another (e.g. massive overs, sub-octaves of the main pitch, distortion, etc.) when used on a mono track or forced to mono.   In the case of wanting to use such an effect on a mono track, I force the interleave to stereo.  Some plug-ins also have stereo/mono switches inside them for cases where you need to use them on a mono track and the context matters to the plug-in.  A few specific plug-ins that come to mind in this context are PSP MixTreble (only works properly with stereo last I checked, and can end up showing a number of issues if it is used with a mono track) and PSP VintageWarmer 2 (works with both stereo and mono, but has a mono/stereo switch that should be set accordingly, though it doesn't seem to be an issue all the time if it is not, just some of the time).

I haven't noticed issues with the above-mentioned plug-ins if just checking a mix in mono, but, by that time, the tracks are already blended in with other things.  And maybe I just haven't noticed. :-)

Perhaps there is something in the processing/effects on the synth, or that specific patch, that isn't mono-friendly?  I wonder, though, if the behavior is different if you freeze the synth versus just running it live.  If it only happens when running it live, it would seem to be more likely to be something related to the synth's operational behavior, as opposed to the sound content.

Rick

That's an idea, I will freeze the synth and see what happens. So if I understand, if what you say is the case, it would not be an issue when listening to the track through a mono system, as long as the synth is mixed on a stereo track in the DAW?

also, what if you mono-ise it using the channel tools?

sharke


That's an idea, I will freeze the synth and see what happens. So if I understand, if what you say is the case, it would not be an issue when listening to the track through a mono system, as long as the synth is mixed on a stereo track in the DAW?

I think it depends on the nature of the problem.  The idea on freezing it is just to check if it is something in the operation of the synth that is having a problem with the mono bus down the line.  I really don't see what that could be since it would still be putting out stereo at the track level (i.e. assuming you don't have the track-level interleave set to mono -- that was the key in the situation with plug-ins I mentioned), but it at least gets that possibility out of the way.  That is, if the problem goes away, it had to be something in operation in that context (probably a bug in something).  However, if it doesn't go away, then it is the nature of the sound output -- i.e. what it is putting out makes problems when converted into mono.
 
If the latter is the case, then it is time to see what can be done about it *if* it is important to have the mono compatibility.  For example, if the issue is that the stereo sound of it had high amplitudes on each side, with phase in sync between the sides, and so, added together in mono, things just got too loud, maybe the solution is to reduce the volume of the track in the mix, even though it wasn't distorting in stereo.  Or maybe it doesn't matter since it would never be heard in mono or the natural mix balance would keep it low enough not to cause a problem. 
 
Just to be clear, though, I would definitely make sure the track-level interleave is set to stereo.  If you need to mono-ize it, using Channel Tools to bring both sides together would be a way to do it.  I do know, though, that some plug-ins really don't like to be run in mono.  In at least one of the cases I alluded to, I'm not even sure why that should be because it doesn't seem like it is inherent to its function (it's easy to see, on the other hand, why something like Channel Tools would demand to be stereo).
 
Rick

Hmm, have not investigated Channel Tools yet (new user here) - thanks guys!

Don't think Razor has a mono/stereo switch, not that I can see anyway. 

Even though you think its not clipping the master bus, it could be over-saturating the master bus or the track. 

Just some 'Food for thought" provided by your local forum user

Cj

sharke


Don't think Razor has a mono/stereo switch, not that I can see anyway. 

Yeah, I wouldn't expect a softsynth to have a mono/stereo switch.  Most tend to operate only in stereo, though some multi-timbral ones do allow for mono in their individual outputs.
 
When I said, "make sure the track-level interleave is set to stereo," I meant in SONAR's channel strip for the track Razor sits on.  However, that may have been needless advice since it doesn't look like there is even an option to change the interleave on instrument tracks in X2 (I don't recall whether there was or wasn't prior to X2 as I've never attempted to force softsynth tracks to mono anyway).  In fact, even if you've inserted Razor through the FX bin in an audio track, which will have an interleave control in the channel strip, it looks like there is no possibility to change the interleave away from stereo once a softsynth is inserted.  (I tried it with Rapture, and, even if you start with an audio track whose interleave is set to mono, inserting Rapture forces the interleave to stereo.) 
 
Rick

rickpaul

...  In fact, even if you've inserted Razor through the FX bin in an audio track, which will have an interleave control in the channel strip, it looks like there is no possibility to change the interleave away from stereo once a softsynth is inserted.  (I tried it with Rapture, and, even if you start with an audio track whose interleave is set to mono, inserting Rapture forces the interleave to stereo.)  

 
Rick

In the Plugin Manager you can select the synth, click on plug-in properties, and there are things like:
Force stereo separation, enable mono processing, etc.


For Razor, if you have the full version of Reaktor, it is quite a simple thing to open up the ensemble and add a summer modules to the output to convert it to MONO. If you need help let me know.