Something Cool I've Been Working On

ownhammer said:
The MPT algo I'm using right now is the best I've heard in retaining the overall tone
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There should be no differences in MPT "algorithms". MPT is not an algorithm. It is a mathematical function. It is the Hilbert Transform of the log of the magnitude. There is one and only one minimum phase transform of a signal. If you hear a difference between two "algorithms" then one (or both) of them isn't implementing the function properly.

Furthermore speaker drivers are minimum phase by nature (1). Tweeters can exhibit some non-minimum phase behavior but for guitar speakers the response is essentially minimum phase. Crossover networks are typically not minimum phase but guitar speakers don't use them. Multiple speakers (i.e. 4x12) may not be minimum phase if captured far-field off-angle. Anyone claiming to hear a difference in close-mic'd IRs is fooling themselves.

If you compare a truncated "raw" IR with a truncated MP IR there may be differences in the low frequency response which get more pronounced the more you shorten the IR. This is because the MP IR "preserves" LF information in the truncated version since it "pulls" the basis functions at those frequencies towards the start. If there is a marked difference then this indicates there is considerable room content in the IR. FWIW, I have not measured significant deviations between normal and MP in the OwnHammer IRs.

MP solves a lot of problems and is inaudible when implemented properly. Humans are very insensitive to phase. Any minor differences in phase between the raw and MP versions would be inaudible. What IS audible is the truncation.


(1) "Most loudspeaker drive units, excluding the crossover networks, exhibit a minimum-phase frequency response"
Digital Signal Processing Tools for Loudspeaker Evaluation and Discrete-Time Crossover Design
MALCOLM OMAR HAWKSFORD, AES Fellow
Centre for Audio Research and Engineering, Department of Electronic Systems Engineering,
University of Essex, Colchester C04 3SQ, UK
 
As someone who just unboxed his Axe II this AM, I'd just like to say thanks to Cliff and the Fractal gang for continuing to do R&D on the unit. I am sure anyone who finds truncated IRs useful will be able to continue to use them going forward. I'm sure that some people will love the Ultrarez stuff regardless of the theoretical underpinnings... and it is very clear this will advance Tone Matching, regardless of where you stand on standalone cab IRs.

So, given that we can have the old and the new at the same time, I'm confused why people do not consider this a clear win for us here: the end users and Fractal fans. I guess one thing you can count on is that people on the net will argue/complain about anything even things that are objectively awesome.

I'm just thankful that the "something cool" Cliff was working on was not a replacement for my shiny new box. LOL! :D

Anyway, as a new II guy, I'm looking forward to staying on the cutting edge of the tech for at least a little while, and I'm sure that with the tireless quest for improvement that Cliff exhibits, FAS can keep us there. :)
 
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all that info, good, good...so...ok, when can we expect some sound files? :D
 
So for live use you need the long tails but without any reflections (if at all possible)


As I said earlier, I like the sound of truncated IRs so that there is absolutely no room in the mix. I like hearing the actual room I'm playing in instead. Will it be possible to benefit from the increase in bass response with UltraRes, but still cut out the room?
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I feel these were valid questions and did not warrant such a blunt and rude reply.
For those that want to faithfully replicate speakers to use with a FRFR system it is very important we know what effect this will have.

But I can imagine if you've record thousand of IRs that are essentially made for use in recordings only because they contain reflections and colouring from preamps and what not, you're not particularly looking forward to record a few thousand that do not include this coloring and only contain what's needed to reproduce the pure sound of the speaker.
 
FractalAudio said:
It is especially noticeable when chugging power chords. You can hear the resonance. It goes "bonggggggg" as opposed to "thuk". Most importantly it sounds "better" IMO.

8. UltraRes is an algorithm that markedly increases accuracy. It gives the frequency resolution of a 200ms IR without additional processing overhead and no added latency.

9. Sometimes people can't see the forest for the trees.
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interest piqued!!!!
 
My use of the term "Sigh..." was intended to be light-hearted and whimsical, apologies if most assume the worst in the attitudes of those who post. :)

One can debate the purist point of view of having a reflection free IR all day, in the end the more functional questions are:
- Can anyone tell a difference if the reflections are minimal or the augmentation pleasing?
- Without the identical source in the room with you, how can you know what is or is not accurate?
- Does the listener care or could any actually tell a functional difference? If they could, would that actually make them leave the venue in protest?
- Does one really expect that most if any can actually provide this without exception, and if they could, would they given the terribly unfair price point expectation put upon vendors in this market?

To me, the answer to all of those is a resounding "No". If I venture to cloning for this niche, I will not guarantee reflection free captures, because I flat out don't care what it is so long as it sounds as close to the source as possible in a number of practical environments and applications. Because it is such a daunting task with such little potential for reward as an intangible unit only (and all of the issues and restrictions that arise being a vendor of such products), it does not rank high in priority to me, nor probably to many other than enthusiasts who would seek no financial gain in the endeavor, and may or may not be able to provide much of a useful or accurate output.

Hope this helps! :)

FractalAudio said:
There should be no differences in MPT "algorithms". MPT is not an algorithm. It is a mathematical function. It is the Hilbert Transform of the log of the magnitude. There is one and only one minimum phase transform of a signal. If you hear a difference between two "algorithms" then one (or both) of them isn't implementing the function properly.
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Quick point of clarification, my reference to variation in tone is directed at a publicly available 3rd party tool which we both know to not MPT properly of which we have spoken about in the past, and was not in reference to your internal MPT process nor mine.

Tonal qualities removed from the equation as I find them to be irrelevant with your and my current MPT capabilities, my preference for non-MPT'd files has mostly to do (in my experience) with volume irregularities as a result of the normalization that follows MPT and how that affects ease of use in auditioning files, particularly with focus on quick A/B changes in critical listening sessions. Under most circumstances, this is a non-issue. :)
 
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Thanks for the reply Kevin.
Without the identical source in the room with you, how can you know what is or is not accurate?
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I was just wondering if the reflections would be audible, like some kind of reverb.
For you it's all obvious but for me it's all chinese.
I just want to understand what this is all about and what if any difference this will make when using it in live settings.
So what I take away from this is that the IRs will be a lot more accurate and the reflections (in nearfields) are very minimal and we shouldn't worry about them. ;)
I do agree that what eventually counts is how pleasing they sound and I must say your IRs never fail to satisfy.
I use them in all my presets.
 
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I do understand the technical arguments but frankly it's all moot. If its sounds better, it is better. If Cliff feels this is something worth chasing then count me in.
 
Many thanks, and apologies if I've been crabby today, this isn't a good week for me to be "visible", so to speak...

My observations, noting my perspective is primarily from the vantage point of the DAW and the behavior of loaders available to them that I personally use, is that through this implementation in the Axe:

- You will get better accuracy and less shave off the very top and bottom as a result of being freed from the imposed truncation levels up to this point. Whether one likes it or not is personal preference.
- Reflections in "good" IR's are blown WAY, and I can't make this text big enough without being totally obnoxious, WAY out of proportion in theoretical discussions of close mic'd files in how much they impact the sound in practical application. Where this becomes an issue is when the reflections are overwhelming or do not augment the sound in the way that the user finds pleasing for their desired result. At noted by Jay, first reflections are going to have the most energy, are the most destructive, and are likely there already for studio type IR's. How prevalent they are and their impact on the sound is nothing anybody but the IR maker has any attempted control of.
- The mic is pointed as the second 6-sided room, the CABINET, and you're going to get infinitely more reflection information from that than the room in close mic'd files unless the room and source setup are highly reflective. The closer the mic is to the driver and the tighter the pickup pattern of the mic, the less reflections will even make their way in on top of that and frequency response resolution will be the noticeable change.
- You will finally have access to the room these files were recorded in, most notably for ambient captures. Unless this was recorded in an incredibly reflective, naked room, this isn't going to transform your tone, just add a little touch of room reverb and some smaller reflective details. Whether one has use for it or not is personal preference.

All that said, there may be extra hoodoo that Cliff is sprinkling in beyond increasing the sample length without noticeably taxing performance, there may not, and that in and of itself is an impressive feat. You won't know until you hear it with your own ears, and chances are what will or will not work for you may have the opposite effect for somebody else. Everybody's a critic whether their qualifications, abilities, and tastes would indicate one should listen to them or not. There is no "right" for everybody.

I can only speak of the effects that I see from truncation in the limited loaders I use outside the realm of FAS, which is why I do not consider myself a viable resource for answers to these questions as they pertain to this platform and need to defer this to others, but wanted to contribute in the event it may help and stop people from bickering about this. :)
 
Interesting read. Really looking forward to hearing these and I feel the "practical" approach is a better viewpoint than the theoretical.

I care on what it sounds like recorded and live and am really happy I found Fractal Audio during version one and bought v2 when it came out.

It has been a great pleasure to use it and ride along as Cliff improves it.

I hope he keeps doing and also appreciate what he is doing because it has worked exceptionally well.
 
FractalAudio said:
(1) "Most loudspeaker drive units, excluding the crossover networks, exhibit a minimum-phase frequency response"
Digital Signal Processing Tools for Loudspeaker Evaluation and Discrete-Time Crossover Design
MALCOLM OMAR HAWKSFORD, AES Fellow
Centre for Audio Research and Engineering, Department of Electronic Systems Engineering,
University of Essex, Colchester C04 3SQ, UK
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wow ! !
Essex has a University... ! !

and there's me thinking that it was all bleached blondes with fake tits wearing bstrd blue eye shadow and fk me anywhere shoes [translated: white stilettos]
 
Maybe MALCOLM OMAR HAWKSFORD, AES Fellow actually is a bleached blonde and has false tits etc? Well you know what those academic audio types are like ....
 
Chris Broderick said:
I am extremely excited about this. For the longest time I have always fought with digital modelers and the pluming, booming bottom end. It wasn't until I started using the Ultra that I could start to tame it, but I hope that this is the solution, and the gap between IR and real cabinets are closed, because then all of these cab options will really come to life. I fired up my spectrum analyzer last night while reading this thread and loaded two files from OH. One was a WAV @48Khz and the other was the same file @48Khz but the truncated Axe II syx version and saw the same lack of resolution in the bottom end when the two were compared. I only know enough in this area to get my self in trouble but Here is to Cliff for continually trying to improve on what is already great!!!
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Chris Broderick creates an account and pops in just to post this. Mind = Blown. Chris, you are one of my guitar heroes and I did indeed put that pick I got from you in Fargo a few years back next to my most beloved James Hetfield pick.
 
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