Microtuning SWAM instruments with Oddsound MTS-ESP

I went on a bit of an adventure with this yesterday and thought I might be able to spare the next person the trouble, although in the end it wasn't too bad. If you have SWAM instruments and hate the way they've implemented microtuning on the GUI, MTS-ESP can be a huge help. Here are my notes, based on setting it up with Reaper (any DAW will work the same way, though).

You need MTS-ESP Suite, which at the time of writing costs £80, so it's going to have to earn its living. There's a demo, which is what I'm working with, although I'll almost certainly buy a license when the demo expires.

The Suite consists of a Master and Client. The Master is loaded as an instrument on its own MIDI channel. It has a very basic built-in synth you can play, which is useful for checking the tuning of other instruments -- this really helped me troubleshoot the setup. You load your Scala file into the Master and you're mostly done with it.

Now load a SWAM instrument in a new track and add the MTS-ESP client in front of it in the signal chain. The Client will send MIDI pitch bends to the instrument to tweak its pitch on the fly. This is all in the manual and works much better than I'd expected, but there are some things to be aware of with the SWAM instruments.

First, ensure the Client's pitch bend range (on the right of the GUI) matches the range of the instrument. For SWAM woodwinds this needs to be 2 semitones when the "Max P.B. Range" in the SWAM GUI is set to 12 (the minimum value). For strings and brass you just need to match SWAM with MTS; in SWAM it's 12 by default and I've never yet found a need to change it.

As far as strings and winds are concerned, you're done at this point. But for brass there's one more step. Go to Advanced -> MIDI and turn Pitch Bend Curve off. Having it on improves playability a bit but conflicts with the pitch bends MTS-ESP is sending, causing the instrument to go way out of tune.

That's it! Now you can control a whole array of SWAM instruments' tunings from the Master application instead of fiddling with their individual tuning GUIs.

Be aware that the pitch bend approach mostly only works monophonically. There's a poly option in the Client that sort-of works with the strings in double stop mode; I got the best results with Retune Type set to "Note + PB" and Update to "Note On Only" but it's not perfect. In particular, when you hold a double stop and move one of the notes, the other seems to retrigger and warble a bit. On other (non-SWAM) VSTs I've tried, poly mode doesn't work at all; the manual says the instrument must support "voice per channel" but I evidently don't own any that do that.

Adding manual pitch bend (e.g. using the wheel during performance) works OK-ish, although on some instruments you get a pronounced warble as the pitch wheel fights with the messages MTS-ESP is sending. I haven't found a way to mitigate that but maybe I will. Manual pitch bending doesn't work at all in poly mode, but since poly mode doesn't work well in general with the SWAM strings it's kind of a moot point.

I had excellent help from both Oddsound and Audio Modelling customer support while figuring this out -- both were really friendly and quick to respond. I should also say they mentioned that the SWAM instruments will be getting Scala file support in the next update, which should fix those double stops on the strings. I think for me the convenience of MTS-ESP makes it worth it; being able to control the tuning of a large number of instruments from the Master is a huge gain in productivity compared with having to load files individually.

MTS-ESP currently works with Modartt's Pianoteq, which I use constantly -- I'm waiting for Organteq to get the same support in the future too, and one of their employees has hinted in the forums that that might be coming this year. Another purchase I'm holding off on for the same reason is Arturia's V Collection; they seem to be adding support incrementally and I hope they eventually get to all the instruments, but for now some of the ones I'm most interested in haven't had the upgrade.

Now I'm off to make some music with all those SWAM instruments, and look into the very intriguing possibility of MTS-ESP in VCV Rack.