P
Pacosipulami
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(keine Sorge Funki, ich verstehe bald auch nur noch Bahnhof.....)Macht Watt Ihr Volt !!!
(keine Sorge Funki, ich verstehe bald auch nur noch Bahnhof.....)Macht Watt Ihr Volt !!!
oder von mir einige Posts bevor http://forum.fractalaudio.com/axe-fx-ii-discussion/75794-something-cool-ive-been-working-4.html#post926086Ich habe da eher an etwas gedacht wie: höhere Auflösung im tiefen Freq.bereich, dafür weniger Auflösung im höheren Freq.Bereich, damit am Ende die Anzahl Multiplikationen ähnlich bleibt --> so etwas wie von AlbertA beschrieben http://forum.fractalaudio.com/axe-fx-ii-discussion/75794-something-cool-ive-been-working-5.html#post926151
It's almost comical seeing the responses on The Gear Page.
While I refuse to get sucked into an argument over there let me state these points:
1. We don't record guitar amps in airplane hangers or anechoic chambers. We record them in studios.
2. When we record a guitar amp we carefully set the amp up in the studio to get the best sound "on tape". This involves moving the amp around, placing gobos, etc. When we collected the Producer's Packs IRs we spent hours arranging the amps/speakers, mics and gobos and playing through the amp and readjusting until we were satisfied. This also included adjusting the preamps and mixing board. In one studio we found that we got the best tone raising the cabs off the floor by a couple feet, orienting them towards a particular wall and placing gobos behind (this was the engineer's standard recording arrangement).
3. At this point our objective of the IR is to capture the sound of that amp/speaker at that position in the room, with the gobos, mics, preamps, etc., etc. The goal is not to capture the raw sound of the amp/speaker in an airplane hanger or outside using a ground-plane measurement and measurement mics. That might be someone else's goal but it is not ours. IOW our goal is to treat the cab, mics, preamps, room, etc. as a whole, as a good engineer/producer would.
4. Subsequent analysis of the data shows that there is significant energy out to 100ms and even beyond. However there is little energy beyond 200 ms or so (as it should be in a well-designed studio). This observation was the catalyst for the UltraRes algorithm. There are other observations about the statistics of the data that I cannot disclose.
5. Some cabinets displayed noticeable resonances at low frequencies. Others did not. The frequency of these resonances were not consistent and, not coincidentally, matched the measured resonance of the impedance sweep. It is a logical conclusion, therefore, that the resonance was NOT caused by the room but by the speaker/cabinet combination. Furthermore a plot of the group delay for the raw data showed that the delay of the resonance was too short to be a room mode. Regardless, whether the resonance is from the speaker or room or mics or preamps is irrelevant. All we care about is recreating the sound of that speaker as it would be recorded as accurately as possible.
6. Truncating an IR destroys information by definition. We don't care where the information comes from, be it the speaker or the room or the mics or the preamps. We want all the information. If a plot of the frequency response of a truncated IR differs considerably from the non-truncated version then we have lost information and concomitant accuracy.
7. NO ONE producing commercial IRs records them in an airplane hanger, for obvious reasons. The best ones are done in a studio using the same technique we used for the Producer's Packs: setting up the cab, adjusting the position, mics, preamps, etc. and playing through the amp/cab and readjusting until the best tone is achieved. The new OwnHammer IRs are an example of this. Many, if not all, of those IRs exhibit significant energy to 100 ms (and likely beyond but the data stops at 100 ms). Truncating them to 20 ms destroys vital information. You can argue the semantics all day long. I've compared truncated and non-truncated and the difference is clearly audible. 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.
Hat Cliff dir bereits geantwortet? Wenn nicht, dann wird es in dieser Richtung gehen. AlbertAs Frage hat er wahrscheinlich auch nicht beantwortet.oder von mir einige Posts bevor http://forum.fractalaudio.com/axe-fx-ii-discussion/75794-something-cool-ive-been-working-4.html#post926086
Der Unterschied zu AlbertA ist aber dass ich keine Ahnung davon habe.....
Jedenfalls sagt er aber leider unsere Idee ab: "Schick Impedanz-Informationen von der Cab IR an den Amp-Block Speaker-tab und ersetze Annahme gegen faktische Größen".
http://forum.fractalaudio.com/axe-fx-ii-discussion/75794-something-cool-ive-been-working-9.html#post927165
;(
Aus meinen Forschungsergebnissen (und da wären wir bei dem was Pacosipulami am "liebsten" täte....) weiss ich, dass sich die Resonanzfrequenz bei geschlossenen Cabinets leicht gegen oben verändert. Bei offenen Bauformen in der Regel gleich bleibt. Dass sich andere Boxen gegenseitig "anregen" ist auch nichts Neues.....das weiss Cliff nämlich auch:It's not a mathematical mistake and nothing to do with windowing.
That peak in the bass response might be the speaker, it might be the room. Looking at the actual IR it appears to be the speaker as there are no discernible early reflections.
The frequency resolution of an IR is the sample rate divided by the number of samples in the IR. The window function has nothing to do with frequency resolution (except for making it even less). So a 1K IR at 48 kHz sample rate has a frequency resolution of roughly 48 Hz. If a speaker has a resonance (formant) at, say 80 Hz with a Q of, say, 3.0, then 48 Hz is insufficient to capture that resonance accurately. You need a frequency resolution of several Hz to accurately recreate that resonance. I chose 80 Hz and a Q of 3 because that's what that response looks like. The Q could even be higher than that.
It doesn't take much mental energy to realize that if you have a narrow formant at a low frequency then you need fine frequency resolution to reproduce that. An 80 Hz formant with a Q of 3 only spans about 25 Hz. Obviously a frequency resolution of 48 Hz is not going to be able to reproduce that.
Windowing only smooths the response even more. This is basic FFT theory. The less time-domain information you have, the less frequency domain information you have and vice-versa. This is the uncertainty principle. I always window IRs with a Hann window.
EDIT: I broke out my impedance measurements for that Vox cabinet and the speaker resonance is 80 Hz.
Somit verstehe ich die erneute Ablehnung dieser Idee nicht (zumal ich sie bereits viermal vorgebracht hatte, das erste Mal im Herbst 2008 - damals wurde sie von Jay Mitchell in der Luft zerissen, da ich geschrieben hatte, das die Interaktion nicht nur auf einer generischen Annahme basieren kann. Im IIer gab es ja dann die Speaker-Tab im Ampblock, die zumindest die ganze Kurve beleuchtet.Don't know. Cabinets with multiple drivers do weird things. It could actually be a slight notch at 60 Hz due to the other speaker resonating out of phase.
Das was ich leider befürchtet habe: http://www.axefx.de/showthread.php/863-Firmware-11-Beta-ist-raus/page3?p=9762&viewfull=1#post9762Jedenfalls sagt er aber leider unsere Idee ab: "Schick Impedanz-Informationen von der Cab IR an den Amp-Block Speaker-tab und ersetze Annahme gegen faktische Größen".
http://forum.fractalaudio.com/axe-fx-ii-discussion/75794-something-cool-ive-been-working-9.html#post927165
;(
Na, da verweile ich doch gespannt auf ForschungsergebnisseWas soll das alles?
Eine IR macht bisher den Sound der Box, nicht aber das Soundempfinden bzw. die Wechselwirkung des Gitarrenverstärkers. Dies wird bisher nur angenommen - und dieses gilt es zu verbessern. Grundsätzlich sei gesagt - Frequenz = Sound, Impedanz = Soundempfinden.