How does it apply to an orchestral template that has so many more instruments than the average song and can cover such a wider dynamic range?
I've always balanced my template using the top layer as my ceiling, but most of the time my music tends to sit on mp with the occasional ff. That obviously almost always results in having a much lower than optimal output level. I haven't tested this myself but surely if you make all the tracks hit -6db max, the output must clip on a ff moment. On the the hand when you don't you do that it gets nearly impossible to average -18db on every track. Of course you can always reduce or the gain at the end using a gain on the out but if that's the case what's the better option? Or should one use multiple templates depending the overall dynamic level of the piece?
Hey Mattia...As you know, orchestral music is far from being slammed like pop music...so you have nothing to worry about in terms of trying to get "hot" levels...From a mixing standpoint...it is utterly important to set your MASTER bus level to no more than 75%...so this works with any DAW, keep it barely hitting yellow. Your individual tracks can certainly peak red from time to time...there is plenty of headroom and it's normal. In the analog world, we used to hit red because it sounded better...LOL BUT the master bus was always reasonable. I would not worry about individual tracks, but rather your STEM tracks in terms of level...then that level into the master bus.
The -18 comes into play when you need to feed analog type plugins. Most analog plugin emulations sound best when fed with -18 DBFS which is zero in analog, but good practice for digital as well. This is optimum for the plugin, NOT for your tracks. Your track output can certainly hit red when mixing. So as Akarin pointed out, use a VU meter as your first insert but set it to RMS...lower your SOURCE audio wave (clip), not the track level to hit the meter at -18. You can also use a trim plugin BEFORE the meter plugin to get your levels...this might be easier. Truthfully...what I do, is use one instance of a VU meter...once my level is set, I move it over to the next track...no need to keep the VU meter on every track once it's set, as this will not change unless you manually increase the audio clip. It is certainly a bit of a pain to do but worth it...again, this is ONLY during mixing once your tracks are rendered. If you don't render...you should. You will have much more flexibility to manipulate the audio than you do MIDI.
In terms of multiple templates: The principal of level still applies no matter what. The difference in dynamics becomes relevant in the mastering stage...how hard are you limiting. Orchestral/movie scores are very dynamic and have very little processing...trailer/hybrid tracks and scores like a Zimmer type or Goransson track can certainly be heavier on the processing in the mastering stage. But anything BEFORE mastering, should always fall within the proper gain staging (usually -14 at this point)...this is of course for best sonics.
If you have a very transparent limiting plugin like the (WEISS MM-1), then it should be easier to get your levels up without sacrificing dynamics.
Hope this makes some kind of sense and answers your question. Sorry for the winded reply...you have helped me with BBCSO and answered some of my questions, just wanted to return the favor.