Properties of Reflection Free IRs

Jay Mitchell

Member
Messages
5,648
I can see the desire to be able to capture that close mic’ed sound in an IR.
While there are almost no far field IRs being marketed, there are tens of thousands of close-mic'ed ones. FYI, there is no "that close mic’ed sound," there's a huge range of such sounds, and there is no universally-shared sonic attribute among them.

Perhaps I should build a 70 meter cube “studio” and hang cabs in the center so I can get rich making 200 ms reflection free IR’s.
Why not? It's a sure thing you won't get rich off silly, irrelevant hyperbole.
 
Last edited:

ML Sound Lab

Vendor
Messages
468
Okay I decided this will be my last post in this thread. I'm finding that it's not going anywhere but it's becoming a waste of time. Thank you guys anyways.

So it's your mistake, but I'm still ignorant? o_O

And what's your point with the 200 ms bit, cus reverb/ambience still doesn't make any sense with 200 ms.
Mistakes are bound to happen when a thread goes for 5 pages without getting anywhere. I've actually shown actual audible and visual proof that even near-field IR's have information up to 200ms.

FractalAudio who came up with the tech would disagree with what you just said, so... :rolleyes:
You mean the company that I've worked with for 6 years and still on-going? All ML Cab Packs use this technique and I believe we had 3-4 packs out before mic+di was presented.

Indeed, you started that logic.
This was posted by you: "I've already told you of some forum members in TGP and Fractal forums that are active users of far-field IRs. It's not just a concept without proof to those of us who use it."

Cool, hope he gives it to ya.
Holding my breath.

FYI for the umpteenth time, no one said that and no one's even trying to prove that.
If that's the case then there's no need for anyone to use these far-field IR's.

I think these quotes summed up this thread for me. Have fun guys. :)
 

TheSchwartz

Member
Messages
287
When creating an IR of a close mic’ed speaker, does the construction of the cab play any significant role in the resulting IR, or does a cab’s characteristics only become apparent as the distance between the speaker and mic increases?
 

burningyen

Member
Messages
14,623
When creating an IR of a close mic’ed speaker, does the construction of the cab play any significant role in the resulting IR, or does a cab’s characteristics only become apparent as the distance between the speaker and mic increases?
In the Helix you can A/B a Vox AC15 1x12 and a Vox AC30 2x12, both with Celestion Blues, using the same mic and the same distance. There's an audible difference.
 

Chocol8

Member
Messages
314
While there are almost no far field IRs being marketed, there are tens of thousands of close-mic'ed ones. FYI, there is no "that close mic’ed sound," there's a huge range of such sounds, and there is no universally-shared sonic attribute amont them.
Obviously there is no single close mic’ed sound. That’s why there are so many IR’s of the same speakers in different cabs with different mics with different mic placements. They sound different from each other. There are also thousands of recordings made with close mic’ed amps with different microphones with different placement etc. that people might want to replicate.

And as you pointed out, the existing IR’s all have reflection issues. I didn’t realize what it was until you created this thread, but I definitely noticed that most IR’s are bass heavy compared to the real cabs and that I needed to EQ my patches for FRFR use. Thanks to you, I now understand why that is.

Obviously I was kidding about a 70 meter cube studio, but I presume it may be possible to measure the room response and digitally remove it from a close mic’ed IR. Way beyond my technical and programming skills, but I imagine possible, and maybe more practical than a true free field recording environment. I’ll leave that for someone else to figure out.

In the meantime, I have a Twin Reverb with original JBL’s and another with Canabis Rex speakers I would like to capture IR’s of. Thanks to this thread and your helpful contributions, I will be sure to embarrass my wife and irritate the neighbors and collect some 2m ground plane samples on a quiet low wind day.
 

burningyen

Member
Messages
14,623
Isn't having a MIC close to the speaker how basically every recorded guitar was captured? When did that suddenly become bad?
This has been addressed many times in this thread already. No one is saying it sounds bad. It's just not an accurate representation of how the cab sounds. If your goal is to get a good sound, whatever works. If your goal is to accurately capture how the cab sounds to the player in normal playing position and to reproduce that through FRFR at a gig, then far-field IRs are uniquely useful. They can also sound nice in a recording.
 

Dave Merrill

Member
Messages
2,451
Much as I hesitate to wade back in here, what is the correct technique for making use of far-field IRs? Earlier in this thread it was said that special knowledge or understanding was required to use them. What do you do besides play your amp sim through them?
 

Jay Mitchell

Member
Messages
5,648
Much as I hesitate to wade back in here, what is the correct technique for making use of far-field IRs? Earlier in this thread it was said that special knowledge or understanding was required to use them.
Nope. You tried to interpret a statement of mine to mean that, but that's not what I said or implied.
 

Jay Mitchell

Member
Messages
5,648
yet people are commenting along the lines of "all IR's suck and these new far-fields will save this planet".
I am well aware of your penchant for hyperbole, but this particular statement - although it is false as regards this thread and these IRs - strikes me as an expression of your worst fears come to life. Just sayin'...
 

yeky83

Member
Messages
2,620
Okay I decided this will be my last post in this thread. I'm finding that it's not going anywhere but it's becoming a waste of time. Thank you guys anyways.
I mean, I'm really trying here. But you're still asking the same questions that have already been answered multiple times by multiple people in multiple threads, ignoring the answers each time. If you want a conversation that goes somewhere, it's on you.
Mistakes are bound to happen when a thread goes for 5 pages without getting anywhere. I've actually shown actual audible and visual proof that even near-field IR's have information up to 200ms.
Mistakes happen, but you don't get to call me ignorant when you make a mistake :dunno
You mean the company that I've worked with for 6 years and still on-going? All ML Cab Packs use this technique and I believe we had 3-4 packs out before mic+di was presented.
Yeah, that company. The same company that replied to a comment you recently made with "It's ignorant, blanket statements like this that drive me crazy..."

You said this:
Quite many advancements in the IR format these days have come from me pushing the envelope. The most notable one is the mic+di capture method that was added to the Axe-Fx II and III that allows you to run tube amps super loud and get an authentic capture of the cabinet being used the way it's meant to be used. (contrary to the claim in above posts that say IR capture is a quiet process) You don't get authentic captures when a cab is not doing what it's meant to be doing. Much like this I'm constantly pushing the envelope and interested in further developing the IR format which is the reason I'm posting in this thread.
Contrast that to this post:
https://forum.fractalaudio.com/thre...g-speaker-cabinets.135191/page-2#post-1599277
If that's the case then there's no need for anyone to use these far-field IR's.
So because close mic'ed IRs don't sound bad, there's no need for anyone to use far-field IRs? Doesn't even make sense.
 
Last edited:

Jay Mitchell

Member
Messages
5,648
When creating an IR of a close mic’ed speaker, does the construction of the cab play any significant role in the resulting IR,
If the structural/acoustic integrity of a cab is a factor in its sound, then that's its own problem. Generally speaking, I'd say an IR of such a cab would be of little value, except possibly as a negative example.

OTOH, if, by "construction of the cab," you mean the dimensions, aspect ratios, type of cab (open, sealed, ported), presence/absence of internal damping material, etc., then a close-mic'ed IR will be much less affected by those parameters as compared to an IR taken at a realistic distance.
 

AlbertA

Member
Messages
66
This has been addressed many times in this thread already. No one is saying it sounds bad. It's just not an accurate representation of how the cab sounds. If your goal is to get a good sound, whatever works. If
your goal is to accurately capture how the cab sounds to the player in normal playing position and to reproduce that through FRFR at a gig, then far-field IRs are uniquely useful. They can also sound nice in a recording.
That pretty much summarizes it :)


I've actually shown actual audible and visual proof that even near-field IR's have information up to 200ms.
You think you have - but what you have actually shown is that you have captured Impulse responses which contain reflections of the room you made the capture on - the reflections indeed have information to even beyond 200ms.

If that's the case then there's no need for anyone to use these far-field IR's.
I think these quotes summed up this thread for me. Have fun guys:).
This thread is about capturing an accurate Impulse response of the cabinet only. If the listener does not sound of the original cab as they play it in the room, then they won't like the sound of the corresponding far-field reflection-free IR either. Your question "Do these far-field IR sound good?" is simply the same as asking "Does the original guitar cabinet sound good?" - that's a subjective question that only the listener can answer for themselves.
 
Last edited:

Dave Merrill

Member
Messages
2,451
It means that lots of the folks who own modelers (and amps, and pedals, for that matter) are clueless. You assume otherwise at your peril.
What I'm asking is, what would an informed user do to make proper use of far-field IRs, that's different from what they should do with near-field ones?
 

AlbertA

Member
Messages
66
Obviously there is no single close mic’ed sound. That’s why there are so many IR’s of the same speakers in different cabs with different mics with different mic placements. They sound different from each other. There are also thousands of recordings made with close mic’ed amps with different microphones with different placement etc. that people might want to replicate.
There's a difference between a recording that used close mic'd amps and an impulse response with partial reflections; in the recording, the reflections are not chopped up. What you get in a typical commercial IR, is the response of the cabinet at that close mic'ed position + partial reflections from whatever room was in. Note I'm not imparting judgment on the sound quality (that's a subjective assessment to be done by the listener)

Note that it is still possible to capture close mic'ed responses reflection free, it's just that it's a bit harder than far-field IMHO - you still need a big room, but to eliminate ground reflections you will have to elevate the cab at least around 12ft (which is what Jay mentioned earlier in the thread); because the most direct reflection will travel 2*elevation_height - Assuming the speed of sound is 343m/s, and that you want the reflection to arrive after 20ms, then the reflection should travel roughly at least 343m/s*.020s = 6.86m. That means the 2*eleveation_height > 6.86m or elevation_height > 3.43m

Obviously I was kidding about a 70 meter cube studio, but I presume it may be possible to measure the room response and digitally remove it from a close mic’ed IR. Way beyond my technical and programming skills, but I imagine possible, and maybe more practical than a true free field recording environment. I’ll leave that for someone else to figure out.
Even if you had the precise room dimensions, the position of the mic, etc - the main problem with reflections is that they cause null's in the response (i.e. because reflections will introduce a comb like response) which is not possible to undo.
 




Trending Topics

Top