the difference between 170ms and 500ms IR lenghth

[shatteredsquare]

To support a 500 ms IR (24,000 samples) would require over ten times the CPU power of a 2K sample IR

i tried searching the forums and looked in the manual but i couldn't find a place that specified in MS other than in random forum posts, but is that to say the max length of IRs the AX3 will load is the utrares length, 180ms? I'm about to order round 3 of AxeFx, on the others i got the room parameter to make up for any lack of preferred ambiance i was missing so i know it's workable, but I've been using official Mesa Cab Two Notes wall of sound a lot lately with Brainworx plugins, and the difference between a Two Notes WoS Mesa cab and a Celestion 500ms IR in Cab Lab is drastic to my ears, the 500ms IR sounds open and loose and alive, without any additional ambiance added.

Is CabLab processing all 500ms of the IR if you load one that long? I got it to load and it sounds great but there isn't a length adjustment in MS and the length graph doesn't have time markers for reference. I was using the official Celestion V30 500ms IRs...https://www.celestionplus.com/products/irs-by-speaker/vintage-30/ comparing them to Cab Pack 13 and Djent.

 

[Valhallir]

You will never ever need a 500 ms IR for live-purposes. If you want to add "room", I really suggest to use the excellent reverbs every AxeFx from the II till now is delievering.
Don't forget: In your studio you really have a very controlled situation. This will never happen in live situations. Placement, stage, location, even the crowd in the hall.....

 

[shatteredsquare]

you are also capturing to a lesser degree the resonance of the cabinet which has it's own harmonics and resonances

wait wait wait you mean when the cab gets spun up and vibrating it has it's own resonance nodes that get added to the sound? like blowing over a coke bottle makes it's own note? or blowing over a coke bottle with a little water in it makes a different note? hmmmm that sounds like witchcraft

 

[Rex]

wait wait wait you mean when the cab gets spun up and vibrating it has it's own resonance nodes...

Every object has its own resonances. Tap on the kitchen table — it sounds a certain way. Tap on a 2 x 4 — different resonances, so it sounds a different way. Cut that 2 x 4 in half and tap on it again — different resonances, different sound.

...that get added to the sound? like blowing over a coke bottle makes it's own note? or blowing over a coke bottle with a little water in it makes a different note?

Resonances aren't notes that get added to the sound. They're just a greater emphasis on sounds that are already there. When you blow over a bottle, you're hitting it with a lot of energy at a lot of frequencies. The note that sounds is the energy that's already in your breath at that frequency.

hmmmm that sounds like witchcraft

Nah, it's just physics. Playing a wonderfully phrased run of notes with feeling and nuance... now that's witchcraft.

 

[shatteredsquare]

The note that sounds is the energy that's already in your breath at that frequency.

were you home schooled

 

[BillyZeppa]

were you home schooled

It's true, the bottle forms an oscillator and the moving air provides the energy 'electricity' to power it. The frequency of oscillation can only be at a specific frequency determined by the volume and relative dimensions of the bottle. A clicker or impulse near the opening of the bottle would also produce a 'ping' at the same frequency. ( btw - no worries, I know you were just kidding, but some people still don't know basic science)

Ok, so a 'speaker in a cab attacked to a tube amp' is also somewhat of an oscillator with its resonant feq., ...like a bottle, right? Or wrong? If so, then what is the decay period for that? Does it exceed the IR time of 170ms?

 

[shatteredsquare]

It's true, the bottle forms an oscillator and the moving air provides the energy 'electricity' to power it.

tracking that, the bottle resonates at it's own note, it oscilates from the energy

but dude said

The note that sounds is the energy that's already in your breath at that frequency

the note is already in your breath

 

[Rex]

but dude said



the note is already in your breath

Okay, I didn't word that very well. The energy in the note that the bottle produces is already in your breath.

Making a note by blowing over the neck of a bottle uses the same mechanism as a whistle. You get a stream of air blowing across the bottleneck, while part of your breath is forced into the bottle and back out, crossing the first stream. That causes periodic interruption of the first stream, and a note is produced.

That whistle mechanism doesn't exist in loudspeakers. A loudspeaker can't produce more energy at a given frequency than it already receives at that frequency.

 

[BillyZeppa]

That whistle mechanism doesn't exist in loudspeakers. A loudspeaker can't produce more energy at a given frequency than it already receives at that frequency.

The typical speaker resonance at about ~100Hz. as modelled in the AFX, is a sort of 'whistle' though, isn't it?

 

[h.c.e.]

The typical speaker resonance at about ~100Hz. as modelled in the AFX, is a sort of 'whistle' though, isn't it?

My, admittedly idiot child like, understanding of that resonant property of the speaker/cab is not that it will cause a harmonic resonance like the bottle example, but rather the property will cause the power amp (due to the physics of impedance and inductive load) to have a jump in output at that particular frequency. Like, not so much a harmonic in the sense of a standing wave, but more of an excitation in the amount of power that is amplified at output? Or, ya know, something like that anyways

 

[BillyZeppa]

My, admittedly idiot child like, understanding of that resonant property of the speaker/cab is not that it will cause a harmonic resonance like the bottle example, but rather the property will cause the power amp (due to the physics of impedance and inductive load) to have a jump in output at that particular frequency. Like, not so much a harmonic in the sense of a standing wave, but more of an excitation in the amount of power that is amplified at output? Or, ya know, something like that anyways

That's interesting. I had envisioned this typical 100Hz. bump for example as a pendulum or low Q tank.
For example I had envisioned that if you ran an instantaneous impulse (ping) into the power amp, the speaker would copy the impulse of coarse, and then it would ring ever so slightly at the 100Hz. resonance, perhaps only three or four cycles before decaying into irrelevance.
AND given this mild 'pendulum' effect, at the same time, a continuous signal at constant level would also increase 'output' at this 100Hz. point, just as you describe... so maybe we're both right.

Another thing of interest is how resonant is a speaker without connection to amp at all - what if you discharge a suitable static electricity buildup across the speaker terminals of a speaker (in cab) and record the result. will the impulse smear out - it has to. what is the spectrum and is there any ringing?

Anyway, I guess for this thread all we need to know is that no audible ringing extends beyond the IR length.

 

[Rex]

The typical speaker resonance at about ~100Hz. as modelled in the AFX, is a sort of 'whistle' though, isn't it?

Nope. Whistles (and Coke bottles) generate frequencies that aren't there by having two air streams interfere with each other. That mechanism doesn't exist in loudspeakers. Resonances don't add anything that's not there already, and they don't amplify any frequency beyond the energy that they're fed with at that frequency.

 

[Rex]

My, admittedly idiot child like, understanding of that resonant property of the speaker/cab is not that it will cause a harmonic resonance like the bottle example, but rather the property will cause the power amp (due to the physics of impedance and inductive load) to have a jump in output at that particular frequency. Like, not so much a harmonic in the sense of a standing wave, but more of an excitation in the amount of power that is amplified at output? Or, ya know, something like that anyways

That's essentially correct. Loudspeakers do have a mechanical resonance, but they also have an electrical resonance as you described, which has an effect on the amplifier's output at that frequency.

 

[benvigil]

Reminds me of John Suhr's story about making an amp for Clapton... how they had to rebuild the cabinet out of cheap pine and make the baffles as loose and crappy as possible so it would "sound right." LOL

 

[shatteredsquare]

My, admittedly idiot child like, understanding of that resonant property of the speaker/cab is not that it will cause a harmonic resonance like the bottle example, but rather the property will cause the power amp (due to the physics of impedance and inductive load) to have a jump in output at that particular frequency. Like, not so much a harmonic in the sense of a standing wave, but more of an excitation in the amount of power that is amplified at output? Or, ya know, something like that anyways

It's both, at the same time. The wooden box itself has an acoustical resonant peak, that's why on a 1960A cab when you palm mute an A power chord it hums and makes your eyes jiggle. But the speakers (electromagnets) have an impedance curve, and the power amp sees more or less resistance along that curve, which makes for another resonance, but that one you can tune in VR land with the speaker page.