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*FREE* Far-Field Session #2 Cab Pack for Axe-Fx Users

The takeaway from all this is that if you truly want the sound of amp in the room the best way to get that is to use an actual guitar cab. This isn't to say that far-field IRs are useless. They will give you a roughly similar sound to a guitar cab but it's just not the same.
Thanks for the great explanation. Maybe this is why I haven't found an FRFR cab I truly love. I always lean toward a guitar cab for the live application, and go direct to FOH. Of course, as we all know, our ears are different. What sounds good to one may sound bad to another, which is why I'm always asking opinions about the live sound of the rig.
 

yeky83

Veteran
Far-field IRs are not the panacea some are making them out to be. Some things need clarification:

1. A far-field IR will still not sound exactly like "amp in the room". The reason for this is that the dispersion of a guitar cabinet is very different than that of a FRFR speaker. An FRFR speaker has far wider dispersion at high frequencies, by design. With a guitar cabinet the low frequencies are less directional than the highs. This causes the cab to interact with the room differently.

So even if you capture a far-field IR it will not sound the same through a FRFR speaker.
I think Jay would respond with:
Unless the cab has an open back and is therefore an acoustic dipole, the difference in room excitation between it and a well-behaved FRFR is negligible. Below 1kHz, the two will be identical. Above 1kHz, the FRFR will tend to suffer less from collapse of beamwidth. The difference favors the FRFR, because, once you dial in a tone you like, it will be much more consistent from one place to another sbove 1kHz.
which makes sense to me.
2. Most of the time we are not in the far-field of a guitar cabinet. At 10 kHz the far-field of a 12" speaker is about 18 ft. So usually we're in the far-field at some frequencies but in the Fresnel zone at others. At a typical distance of, say, 5 ft. we are only in the far-field at frequencies below roughly 3 kHz. Above that we are in the Fresnel zone.

3. Because of #2 the sound at each ear can be quite a bit different. That six inches or so between our ears makes a big difference. When using a far-field IR the same sound will be presented to each ear. Even when in the far-field the sound changes pretty dramatically vs. angle because the dispersion is a function of frequency. One ear will hear more highs than the other.

4. A cab with more than one speaker creates significant challenges. For example, a 4x12 has a far-field at 10 kHz that's roughly 100 feet! If you capture an IR of that cab at, say, 10 feet you are nowhere near the far-field. At anything other than nadir (aka boresight, 0 degrees) the individual speakers will contribute with different times of arrival. This results in extremely phasey sound (we were able to get some 4x12 IRs by using a special trick but in general you need to be very far away).

We don't hear this phasiness when listening to the real cab though because of #2. We get very different signals at each ear and our brain processes these. When using a Fresnel-zone IR of a 4x12 the same signal goes to both ears.
This part is interesting, thank you for writing this out. How would you say our brain interprets this interaural difference due to being in the nearfield? Does it affect some perception of stereo?

Hm, if I covered one ear, would a 4x12 sound phasy?
The takeaway from all this is that if you truly want the sound of amp in the room the best way to get that is to use an actual guitar cab. This isn't to say that far-field IRs are useless. They will give you a roughly similar sound to a guitar cab but it's just not the same.
I hope there's more farfield IRs to come from FAS, and hopefully reflection-free ones!
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
I think Jay would respond with:
which makes sense to me.

This part is interesting, thank you for writing this out. How would you say our brain interprets this interaural difference due to being in the nearfield? Does it affect some perception of stereo?

Hm, if I covered one ear, would a 4x12 sound phasy?

I hope there's more farfield IRs to come from FAS, and hopefully reflection-free ones!
Try the free ones. The reflections are negligible. They sound great, better than Jay's IMO.
 

lauke-lux

Forum Addict
IMHO the interest is having the room ir/close ir/rear ir of the same cab based on the same time base. Did this with some Ownhammer IR's I got, and following some Scott Peterson advice (45%/50%/5%) so say -0.5dB/0.db/-13dB) auto-trimmed in Cab Lab 3. Interesting results and through my CLR cab I come close enough to a standard cab mix they supplied with the pack and that I use very often (fat mix OH 412 MAR PR-H75-M75-01F6). Also null mic value impacts a lot the low thumb. It remains a matter of taste though IMHO. Anyway this has been a welcome and useful occasion to refresh my approach to use of IR's and to dig FAS Cab Lab. It's worth it to spend a few morning hours as ears are fresh to tweak some nice mixes.
 

Robboman

Fractal Fanatic
I wish I could try these (AX8 only here). For me they're not 'free' though. So far they cost me 2 hrs of my time because I got all sucked into this thread and that 38 page monster thread over on TGP with Jay.

I seem to dive into these science threads every so often. I start out keenly interested, trying to learn something, but after a while my eyes glaze over.

Then the comical absurdity of all this sets in. I get this image of guitar scientists wearing white lab coats as they capture data sets, create and post charts, analyze results, furiously debate (fight) over technical minutiae for months on end.

Tone matters. A lot. So I get it, I do this too at times.

When I get too deep in the nerd rabbit hole I stop and think.. what would Tom Petty have to say about all this? Then I feel a little ashamed :)

I feel better when I get back to creating music. Gets my mind right.
 

lauke-lux

Forum Addict
I wish I could try these (AX8 only here). For me they're not 'free' though. So far they cost me 2 hrs of my time because I got all sucked into this thread and that 38 page monster thread over on TGP with Jay.

I seem to dive into these science threads every so often. I start out keenly interested, trying to learn something, but after a while my eyes glaze over.

Then the comical absurdity of all this sets in. I get this image of guitar scientists wearing white lab coats as they capture data sets, create and post charts, analyze results, furiously debate (fight) over technical minutiae for months on end.

Tone matters. A lot. So I get it, I do this too at times.

When I get too deep in the nerd rabbit hole I stop and think.. what would Tom Petty have to say about all this? Then I feel a little ashamed :)

I feel better when I get back to creating music. Gets my mind right.
I confirm, nobody ever asked me "Hey man, what cab IR do you use for your Axe Fx ?" after the rare performances I do as an amateur....
 

yeky83

Veteran
Try the free ones. The reflections are negligible. They sound great, better than Jay's IMO.
I bet they sound great. Just doesn't seem quite what I'm looking for since I'm having a hard time grasping how the reflections could be considered negligible. But will do sir, I will try them out.
 

merlin17

Forum Addict
They sound fine, but as I seem to be sensitive to comb filters I like Jay's more (although the speaker he used in the "free" IRs would not be my favourite). I hope somebody (Jay himself, Fractal, ...) will come out with a really reflection free set of IRs of some classic speakers/ cabs. It seems there is a market for it and quite some people would pay for them (including me)...
 

Joe Bfstplk

Veteran
You should align impulses ideally but sometimes a little misalignment adds character.
I like to put the room/far field IR's first big peak just a tiny bit after the close-mic IR's initial peak, generally. That lines them up so bass response from the close-mic'ed IR is not trashed from out-of-phase cancellation and just the boominess is reduced, and any reflections in the FF IR seem like they fit better to give an 'in the room' vibe.

 
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skunc

Inspired
This may be one of my favorite threads I've read in a while. I now have a better understanding of IRs and FRFR cabs. I appreciate the gift of the IRs and can't wait to try them out! No company does anything like this. Thank you.

Bottom line; if it sounds good, it is good. If it sounds bad don't use it. No one is going to notice this level of reflection in a single IR on the guitar track out of the mix.
 
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brianv4

Forum Addict
I've been a bit apprehensive about trying these. First, I'm happy with my tones. Second, never heard one (FF IR) that improved it. Until now. Just when you thought you were at tonal nirvana... BAM! These are freakin' awesome! If you haven't yet, try 'em. Thanks Fractal!
 
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666was999

Forum Addict
Cliff's explanation about the relation between frequencies and the nearfield vs farfield made me think about what would happen if I cut away the nearfield IR above a certain frequency and above that there's only the FF IR left. So I did.
It sounds interesting, not bad for an AITR kind of like monitoring. It's not a sound that I'd send to the console on a gig though.
Next step is to use an X-over in front of the two cab blocks, maybe that's the right trick?
Anybody tried something like that?
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
I bet they sound great. Just doesn't seem quite what I'm looking for since I'm having a hard time grasping how the reflections could be considered negligible. But will do sir, I will try them out.
The magnitude of the reflections is very low. Comb filtering occurs when you add two signals where one is delayed vs. the other. If the magnitude of the two signals is equal the notch depth is infinite. As the magnitude of one decreases the depth of the notch decreases. Once you get -20 dB down or so the notch is insignificant. The amplitude of the reflections in these IRs is -30 dB down.

For example if you have two equal signals and one is delayed by, say, 10 ms there will be infinite notches at 50, 150, 250, ... Hz as the delayed signal will be destructively interfere with the non-delayed signal at those frequencies (x - x = 0 => -inf dB). If the amplitude of the delayed signal drops to 1/2 the depth of that notch is now only 6 dB. I.e. x - 0.5x = 0.5x => - 6 dB. If the amplitude drops to 0.1 (-20 dB) then the notch is very small: x - 0.1x = 0.9x = -0.9 dB. At -30 dB the notch depth is x - 0.03x = 0.97 => -0.26 dB. This means ~1/2 dB amplitude variation over the spectrum. Our ears can't hear that.
 

yeky83

Veteran
The magnitude of the reflections is very low. Comb filtering occurs when you add two signals where one is delayed vs. the other. If the magnitude of the two signals is equal the notch depth is infinite. As the magnitude of one decreases the depth of the notch decreases. Once you get -20 dB down or so the notch is insignificant. The amplitude of the reflections in these IRs is -30 dB down.

For example if you have two equal signals and one is delayed by, say, 10 ms there will be infinite notches at 50, 150, 250, ... Hz as the delayed signal will be destructively interfere with the non-delayed signal at those frequencies (x - x = 0 => -inf dB). If the amplitude of the delayed signal drops to 1/2 the depth of that notch is now only 6 dB. I.e. x - 0.5x = 0.5x => - 6 dB. If the amplitude drops to 0.1 (-20 dB) then the notch is very small: x - 0.1x = 0.9x = -0.9 dB. At -30 dB the notch depth is x - 0.03x = 0.97 => -0.26 dB. This means ~1/2 dB amplitude variation over the spectrum. Our ears can't hear that.
I guess then I'm left wondering why there's 5, 10dB notches that's clearly visible (and audible too I assume) in the bass range of the graphs that @AlbertA and @DLC86 posted here.
 

Lilarcor

Inspired
Because these notches aren't caused by reflections but by other factors like the inherent frequency response of the speaker/cab? I'm no expert. That's just what came to my mind after reflections had been excluded by Cliff.
 
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