Will we see improvements/new tech regarding speaker cabinets?

Volterra kernels

talk dirty

BTW Volterra also got involved in population/ecology biology (specifically Lotka-Volterra competition)

Vito_Volterra.jpg




flubby, flabby and farty

Out of context, this is even more awesome.
 
If it was intended, disregard, but in this case it was kinda weird. A more logical start point would have been 1:39. Not a big deal, just thought you might like to know.

Interestingly enough, I actually did just that and copied it right from the address bar and it still did it that way. I know I didn't use the share feature because I went back to look at the video and had to remember where its at, so I didn't recently do that for sure.

But I did kind of want it to start at that point anyway because thats around when he starts discussing the modeling portion.
 
Interestingly enough, I actually did just that and copied it right from the address bar and it still did it that way. I know I didn't use the share feature because I went back to look at the video and had to remember where its at, so I didn't recently do that for sure.

But I did kind of want it to start at that point anyway because thats around when he starts discussing the modeling portion.
Right on, then.
 
Really interesting discussion, but a question arises: could the method to capture IRs hide some phenomena that occurs only on some circumstances?

I mean, an IR is almost always captured with a sine sweep which is just a single frequency being reproduced by the speaker at a time, but this would not detect for example some irregular motion of the cone that might occur when the speaker tries to reproduce more complex sounds.
Could be interesting to compare IRs of the same cab+mic configuration captured using different test tones (white noise, pink noise, double sine sweep, music program) to see if the frequency response remains the same across all of them.

But maybe someone has already done this kind of tests or maybe my knowledge is too limited to talk about these things and my argument is just "bovine stools" :)

The best test signal is an exponentially swept sine, to understand why, you need to deep dive into the math, I pointed some relevant papers here: https://forum.fractalaudio.com/threads/firmware-supplied-irs.48818/page-3#post-637628
 
Is this "in theory" or actual tests have been done?
Found another link for ya of actual tests being done:
http://www.montefiore.ulg.ac.be/~stan/ArticleJAES.pdf

Quality of the impulse response can be different with different methods, but not in the way you're insinuating, which seems to be "maybe we're missing something with a sine sweep" vibe. An impulse response is an impulse response. It's a mathematical process, and math is just... true period, not "in theory" :p

@AlbertA knows a ton more! Follow his link! I don't know why I'm still replying to this thread with all these qualified DSP people present! Haha.
 
All this geekery is fun, but IR tech itself isn't the problem. It's the TENS of THOUSANDS of cab IRs that exist today that sound bad, average, OK, meh, prettygoodbutkeeptrying, etc etc...) You audition thousands to find one keeper, but by that time you don't trust your own ears. The infamous IR rabbit hole.

What we REALLY need is a better way to identify / rate / rank the best of the best IRs. I understand 'best' is subjective, and I have no idea how to even approach this issue.

But IT IS an issue, and whomever develops an elegant way to conquer it will be a hero!
 
I think this is a quite interesting debate, and I certainly don't think the speaker modelling is 'done'.

I was a bit surprised to see that IRs captured at different volumes look completely similar. This is great, but the next big thing must be speaker compression and speaker distortion. I think the recent firmwares have taken giant steps in this direction, but I feel like we are not done yet.

Few things are less satisfactory than loading a modeller with an AC30 model and a Celestion Blue IR, if no speaker compression is added. The compression of a Blue when driven to its maximum is astonishing and such a big part of that sound, that chime. The same goes to a certain extent with Marshalls and Greenbacks, it's just more speaker drive than compression (as I hear it). We now have tools in AxeFX to get close, but I feel like they are a bit rudimentary at this stage. Is it really the same flavor of compression for all speakers? Is the drive characteristic really the same? Just more/less and a time constant - Is this really enough control?

It will be perfect, when I just tell the modeller what type of speaker I am using and based on the virtual output volume the correct speaker compression and speaker drive settings are automatically applied. I am glad, this is not my task :)

I am actually quite confident that the amp modelling is very close to perfect, and I am so happy that @FractalAudio has really dug into modelling of the non-linear speaker (and amp-speaker interaction) behavior in the latest firmwares. This is the one remaining area, where I feel that the modelling is still a bit lacking.
 
Found another link for ya of actual tests being done:
http://www.montefiore.ulg.ac.be/~stan/ArticleJAES.pdf

Quality of the impulse response can be different with different methods, but not in the way you're insinuating, which seems to be "maybe we're missing something with a sine sweep" vibe. An impulse response is an impulse response. It's a mathematical process, and math is just... true period, not "in theory" :p

@AlbertA knows a ton more! Follow his link! I don't know why I'm still replying to this thread with all these qualified DSP people present! Haha.
I'll surely check both your and @AlbertA 's links, thanks! ;)

Anyway I was not insinuating anything against math and impulse responses, I was just wondering if there could be non-linearities that were not revealed by the usual process to capture IRs. Pure curiosity :)
 
What I would love to see is some way to capture the sound of the speaker across its whole surface as opposed to just one fixed mic position. You could then maybe have the ability to move the mic position and angle around the speaker cone virtually instead of changing IR's for each fixed position. That would be really freaking cool for tweaking out exactly the cab sound you want.

Maybe something like taking a series of IR shots from a bunch of measured positions around the speaker and then interpolating some kind of master "image" of the whole speaker's sound?

Thats what Nebula does I believe. Ownhammer used to (or may still do?) release their cab packs as Nebula library packs as well. I guess that having something like that within the Axe III would be the next step for giving users total control over their tone.
 
The speaker compression parameter mimics the compression that comes from the speaker
I misread your previous post and so deleted my response to it. Your main point is that you want a more automated speaker compression & drive values, but I thought you were trying to say something else and responded in an irrelevant way. My bad!
 
I misread your previous post and so deleted my response to it. Your main point is that you want a more automated speaker compression & drive values, but I thought you were trying to say something else and responded in an irrelevant way. My bad!
That was certainly one of my points, but also, I am not convinced that all speakers can be described with the same "Compression amount", "Time constant" and "Speaker drive". I would expect AlNiCo, Ceramic and Rare Earth magnets in speakers to relax in quite different ways - not just with different time constants.

But again, I think FAS has taken giant steps down this path already, I just hope, it will be even better in the future.
 
That was certainly one of my points, but also, I am not convinced that all speakers can be described with the same "Compression amount", "Time constant" and "Speaker drive". I would expect AlNiCo, Ceramic and Rare Earth magnets in speakers to relax in quite different ways - not just with different time constants.

But again, I think FAS has taken giant steps down this path already, I just hope, it will be even better in the future.
I wouldn't think different magnet types would affect Speaker Compression and Time Constant parameters, as that's related to the power amp and voice coil related compression to my understanding.

It might affect Speaker Drive...? Maybe the differences in magnetic strength will affect the knee and ratio of the magnetic compression as the driver goes into over-excursion. Would this be noticeable? Is this already accounted for in the Speaker Drive parameter? Dunno :p But I get your point.
 
I wouldn't think different magnet types would affect Speaker Compression and Time Constant parameters, as that's related to the power amp and voice coil related compression to my understanding.

It might affect Speaker Drive...? Maybe the differences in magnetic strength will affect the knee and ratio of the magnetic compression as the driver goes into over-excursion. Would this be noticeable? Is this already accounted for in the Speaker Drive parameter? Dunno :p But I get your point.

I would think the hysteresis and magnetic hardness (how robust the magnetization is to external fields) of the magnets has an influence on the compression characteristic (and drive). I have never measured anything in this nature, but I have a good bit of general knowledge of magnetic materials. This is also why I might suspect that different magnets might have a different compression release curve. Again, I am just thinking out loud based on my experience with (electro)magnetism in completely different application fields.
 
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