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"Full Res" AITR vs. FX blocks?

touch33

Inspired
I've listened to @FractalAudio's sound files demonstrating the new Full Res IRs – pretty cool! If I'm following along correctly, the FullRes IR captures are done so that they capture both the sound of the cab AND the room "ambience" the cab was captured in – with the end result being the "room" is permanently "baked into" the cab IR (?). Since I often use my AFX3Mk1 for IEM/headphone "noodling", I've relied on my studio engineering chops and use of FX blocks to create a variety of stereo "rooms" for some of my presets. One of the purposes of using FX blocks (delay, reverb and EQ) is to create a highly-controllable pseudo-stereo environment – my own personal "AITR" – which makes me wonder: are the FR IR's stereo or mono, and do they have the ability to be tailored to control the apparent size/sound of the ambience and its mix with the "dry" preset sound?
 

mixermang

Inspired
do they have the ability to be tailored to control the apparent size/sound of the ambience and its mix with the "dry" preset sound?

if you have a long tail big space and drop the length down to 512 or 256 it effectively makes it a obvious smaller space, but without an actual length dial you only get the 4 or 5 set lengths, you can't step through the whole area. if you could step through the whole length in milliseconds you could tune the tone of the space, and if you could select start and end points of the window you could really tune the way it sounds without even needing EQ by grabbing just the section of the reverberation you want. that's all wishes though right now. If cab block had a overall mix knob you could use cab 2 to mix in a little like a reverb block, otherwise got to finagle your own parallel rig. if cab slots ever got serial link capability, the level knobs (if they retained their current behavior) would act as mix control of that slot relative to the previous slots, they are basically mix knobs now just all running internally in parallel
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
if you have a long tail big space and drop the length down to 512 or 256 it effectively makes it a obvious smaller space, but without an actual length dial you only get the 4 or 5 set lengths, you can't step through the whole area. if you could step through the whole length in milliseconds you could tune the tone of the space, and if you could select start and end points of the window you could really tune the way it sounds without even needing EQ by grabbing just the section of the reverberation you want. that's all wishes though right now. If cab block had a overall mix knob you could use cab 2 to mix in a little like a reverb block, otherwise got to finagle your own parallel rig. if cab slots ever got serial link capability, the level knobs (if they retained their current behavior) would act as mix control of that slot relative to the previous slots, they are basically mix knobs now just all running internally in parallel
It doesn't work that way. If you pick just a section of a reverberant IR (i.e. an actual reverb IR) it won't sound natural. Even if you fade-in and fade-out it will still sound weird because you've lost the natural decay. A small space decays rapidly. Truncating an IR of a large space won't sound anything like the IR of a small space because the decay will be all wrong. You could try to apply an envelope with a waveform editor and it might sound closer but it's still not the same thing so there's no point in doing that.

Truncating speaker IRs works because the decay is very fast and beyond a few hundred samples there's not a lot of information but if you truncate a long reverberant IR it won't sound at all natural.
 

steadystate

Fractal Fanatic
To me, one of the main reasons to use a full res IR is the fact that it is capturing the speaker and cab in the mid/far field along with the room ambience. This is totally different than using a close-miced IR with a reverb block. I'm assuming that full res IRs will typically not use close mics. Is this a fair assumption?
 

touch33

Inspired
All points well taken. Part of how I make a living is using dual-FFT analysis to acoustically investigate/tune everything from studios to concert halls to arena/stadium facilities. Another part is doing music/film mixing and electronically “creating” acoustic spaces for dry tracks. Given the plethora of super delays and great reverbs in the AFX3 I’ve yet to feel limited by the “rooms” I’ve been able to create “in the box”.

I’m trying to imagine how having a combined “mic’d cab/mic’d room” IR whose two components are inextricably linked to one another (if that’s what a Full Res is) would somehow be superior. Easier for some, perhaps — loading up a pre-made IR is certainly simple enough, and dialing-in FX can be a very special rabbit hole — but is there a technical factor that leads to better perceived sound quality that I’m not taking into account?
 

mixermang

Inspired
is there a technical factor that leads to better perceived sound quality that I’m not taking into account?

since it's all actual space all the reflections will always be real, plus you can get it as small and intimate as you want, unlike algorithmic early reflections if they aren't ratioed and tiered and diffused properly, ringing and humming when you get up close
 

mixermang

Inspired
I'm assuming that full res IRs will typically not use close mics. Is this a fair assumption?

you could do it
1. close mic and far mic mixed
2. just close mic 1300ms long HiFi IR
3. just far mic room sound
actually you could do it infinite ways I guess, mix down five mics at once if you want
 

Corinthian

Inspired
Couldn't we just capture a short IR from the room (so the frequency spectrum is accurate) and feed it into a room reverb?
 

steadystate

Fractal Fanatic
I’m trying to imagine how having a combined “mic’d cab/mic’d room” IR whose two components are inextricably linked to one another (if that’s what a Full Res is) would somehow be superior. Easier for some, perhaps — loading up a pre-made IR is certainly simple enough, and dialing-in FX can be a very special rabbit hole — but is there a technical factor that leads to better perceived sound quality that I’m not taking into account?
My interpretation of this is that the main difference ( and reason for using full-res) is the use of a far-field IR combined with the room reflections. It's not going to sound like a close-miced IR, whether or not the reverb is baked into the IR or is generated algorithmically. The fact that the far field response and room reflections all come from the same capture should make for a realistic experience when recording direct. At least, that's my take on it based on what I've read.
 
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