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Why do Cab IR's seem lacking?
Old 2nd July 2020
  #211
Speakers respond linearly to the voltage going into them.
Old 2nd July 2020
  #212
Quote:
Originally Posted by Raaphorst View Post
Speakers respond linearly to the voltage going into them.

Well, maybe in the virtual world.

In the real world, they come close at very low voltages....



-tINY

Old 3rd July 2020
  #213
Gear Nut
 
brainditch's Avatar
 

Quote:
Originally Posted by Raaphorst View Post
Speakers respond linearly to the voltage going into them.
Didn't want to rain on your parade, but no. Linearity is only so in real systems as a point of comparison, i.e. a relatively small range of energy exchange between the limits of Brownian Motion and Molecular Disintegration. The center of this Linear portion of the scale might be thought of as a Point of Reflection, extending equally higher and lower in energy. Both the top and bottom of the scale have non-linearities, usually a Curve of Instanciation at the bottom, and a Curve of Saturation at the top. This entire curve is known as a Logistic Curve (exponential at certain portions), and is the most common energy curve (and therefore for nearly all actions) in the universe. SO no, the energy-related responses of speakers (or guitar strings, for that matter) are not truly linear, but may conveniently be described as such WITHIN LIMITS.
Old 3rd July 2020
  #214
Quote:
Originally Posted by brainditch View Post
Didn't want to rain on your parade, but no. Linearity is only so in real systems as a point of comparison, i.e. a relatively small range of energy exchange between the limits of Brownian Motion and Molecular Disintegration. The center of this Linear portion of the scale might be thought of as a Point of Reflection, extending equally higher and lower in energy. Both the top and bottom of the scale have non-linearities, usually a Curve of Instanciation at the bottom, and a Curve of Saturation at the top. This entire curve is known as a Logistic Curve (exponential at certain portions), and is the most common energy curve (and therefore for nearly all actions) in the universe. SO no, the energy-related responses of speakers (or guitar strings, for that matter) are not truly linear, but may conveniently be described as such WITHIN LIMITS.
Are there simple ways to measure it, other than running sines through it?
Old 3rd July 2020
  #215
Gear Nut
 
brainditch's Avatar
 

Quote:
Originally Posted by Raaphorst View Post
Are there simple ways to measure it, other than running sines through it?
In short, no. Any complex phenomena requires complex analysis. There are some software packages that are free that can provide some intermediate complexity waveforms and generate time-based analysis that is moderately complex, such as Room E.Q. Wizard and ARTA, but of course these are really just the basics. Most of the better ways and means require some sophisticated external hardware and expensive software.
Old 3rd July 2020
  #216
Lives for gear
running sine sweeps at least will deliver some guesses about resonances and modes. this is by far not sufficient, as 1) the timing is crucial, guitars have a strong attack, and 2) there is intermodulation and this will create new resonances based on the sum and difference between all involved frequencies, and not covered with a single sine.
as the cone is a mechanical thing that can bend and has a certain softness, there is also a form of nonlinear compression, and energy loss, so different modes concurring, can eat energy from each other, which is very hard to predict, and may even be a little bit non-deterministic, or depending in the most complex ways on the status a few milliseconds in the past.
Old 3rd July 2020
  #217
Must say I love IRs, but maybe I like the total dynamic feel it offers. Am also a fan of the old Palmer Speaker Simulator PDI-03 and love using EQ with a steep high pass. Love that super direct sound. And adding ambience with another IR.
Old 3rd July 2020
  #218
Lives for gear
Quote:
Originally Posted by Raaphorst View Post
I believe when we see THD in a signal measured by a microphone, something like a Shure SM57, it's extremely likely the THD is coming from the mic and not from the speaker. Also, check info on: Maximum Linear Excursion for speakers.
No.
https://service.shure.com/s/article/...language=en_US

Quote:
Originally Posted by John Eppstein View Post
Believe what you like, but you're wrong. The speasker produces MUCH more distortion than the mic. Not that a 57 is really a good mic to use as a reference, but still.....

"Maximum linear excursion for speakers" is not relevant. We are talking about the behavior of speakers long before they hit maximum excursion.
Given that guitar speakers specifically tend to have near-zero Xmax (linear excursion, based on coil/gap geometry), it's entirely possible they're typically operated at/near/past the supposed mechanical linear range.
You can see this in my data: in the low frequencies, the distortion skyrockets with power input, indicating Xmax is being thoroughly exceeded.

Quote:
Originally Posted by Raaphorst View Post
Speakers respond linearly to the voltage going into them.
Up until high levels, the frequency response remains constant.
The distortion levels do not.

I've presented the data.

Quote:
Originally Posted by NeoVXR View Post
running sine sweeps at least will deliver some guesses about resonances and modes. this is by far not sufficient, as 1) the timing is crucial, guitars have a strong attack, and 2) there is intermodulation and this will create new resonances based on the sum and difference between all involved frequencies, and not covered with a single sine.
as the cone is a mechanical thing that can bend and has a certain softness, there is also a form of nonlinear compression, and energy loss, so different modes concurring, can eat energy from each other, which is very hard to predict, and may even be a little bit non-deterministic, or depending in the most complex ways on the status a few milliseconds in the past.
Fourier takes care of most of this. If you use a sine sweep, you can plot frequency and phase response, which can then be transformed into an impulse response, showing us time-domain behaviour in a more useful way.

The hysteresis of the cone itself is an interesting notion, but I'm not sure how far that'd go, nor how audible the result would be.

With regards to IMD, I'll leave this:

Quote:
Originally Posted by Wikipedia
IMD is only distinct from harmonic distortion in that the stimulus signal is different. The same nonlinear system will produce both total harmonic distortion (with a solitary sine wave input) and IMD (with more complex tones).
Which suggests that a sine sweep (which gives you harmonic distortion curves) should provide plenty of data.

IMD is measured differently, but the mechanism producing IMD is the same as the one producing HD, just operating under different conditions.

Chris
Old 4th July 2020
  #219
Lives for gear
the usual transformational math that works with superposition and integral, is only valid if there is no distortion.
a sine sweep will not have the same result as a dirac pulse, or a white noise, or a pulsed noise.
phase relationships cannot explain the timing behavior sufficiently.
thus, I proposed some "delta" tech, to introduce at least some of the non-linearities. but in the first place, we need a library of impulses that are cleaned from those non-linearities. I guess this can be done best with putting together the different methods of measuring, with the help of pattern recognition and data mining.
Old 4th July 2020
  #220
Lives for gear
 
zvukofor's Avatar
Meanwhile, i disliked the sound of just IRs as speaker simulation for like 8 years, but i found a nice way to bring back that kind of nonlinearities to sound.
It is not the same as a nonlinear model of a real speaker i couldn’t care less about, but it gives a lot of what i was missing using IRs alone. Just a compressor with short enough A and R times gives very similar distortions - more on LF, less on HF, adjust to taste, brings back a lot of nonlinearities that lacks in current cab models.
Old 7th July 2020
  #221
Lives for gear
Quote:
Originally Posted by NeoVXR View Post
phase relationships cannot explain the timing behavior sufficiently.
Citation?

There's an awful lot of maths and existing technology that relies on the relationship between phase and time.

Chris
Old 7th July 2020
  #222
Lives for gear
don't take stuff out of context.
what time-dependent saturation does to the harmonics and to the resulting wave form, cannot be modelized with phase, except in thin slices, and you need windowing etc. etc., it does not truly represent the process as a whole.
requirements: quasi-stationary, linear (= no distortion, continuous transfer curve)

(that's how we in the first place entered the whole debate and attempt to engineer something different. the guitar amp cannot be represented with some impulse. neither the amp component nor the speaker component.)
Old 3rd August 2020
  #223
this is also a very interesting paper concerning modern black-boxing techniques (which I think Kemper is also using): https://www.researchgate.net/publica...eural_Networks
Old 4th August 2020
  #224
Quote:
Originally Posted by Raaphorst View Post
Speakers respond linearly to the voltage going into them.
WANNA BUY A BRIDGE? I have several available throughout the country.... New York, San Francisco, Louisiana. You can make a lot of money on the tolls.....?

We would like speakers to be linear, but the truth is that only electrostatics really are, and only with a limited amount of low end.

Planars are coming close.

Both are lots of money and don't go very loud.

Any moving coil dynamic speaker is not going to be linear due to drag induced by the non-linear spring action of the surround and spider. And every one is non-linear in a different way, which is why speakers don't all sound the same.

The other enemy of linearity is The Laws of Physics, specifically, inertia and momentum, all that Newtonian stuff.

When a speaker, having mass, is moving in a particular direction it does not want to change. The suspension imposes a mechanical brake.

They do TRY to behave in a linear manner... But they fail.
Old 4th August 2020
  #225
Quote:
Originally Posted by brainditch View Post
Didn't want to rain on your parade, but no. Linearity is only so in real systems as a point of comparison, i.e. a relatively small range of energy exchange between the limits of Brownian Motion and Molecular Disintegration. The center of this Linear portion of the scale might be thought of as a Point of Reflection, extending equally higher and lower in energy. Both the top and bottom of the scale have non-linearities, usually a Curve of Instanciation at the bottom, and a Curve of Saturation at the top. This entire curve is known as a Logistic Curve (exponential at certain portions), and is the most common energy curve (and therefore for nearly all actions) in the universe. SO no, the energy-related responses of speakers (or guitar strings, for that matter) are not truly linear, but may conveniently be described as such WITHIN LIMITS.
Jeez, a person who's actually wordier than me!

Even if you can't spell "instantiation"....
Old 4th August 2020
  #226
Quote:
Originally Posted by chris661 View Post
No.
https://service.shure.com/s/article/...language=en_US



Given that guitar speakers specifically tend to have near-zero Xmax (linear excursion, based on coil/gap geometry), it's entirely possible they're typically operated at/near/past the supposed mechanical linear range.
You can see this in my data: in the low frequencies, the distortion skyrockets with power input, indicating Xmax is being thoroughly exceeded.



Up until high levels, the frequency response remains constant.
The distortion levels do not.

I've presented the data.



Fourier takes care of most of this. If you use a sine sweep, you can plot frequency and phase response, which can then be transformed into an impulse response, showing us time-domain behaviour in a more useful way.

The hysteresis of the cone itself is an interesting notion, but I'm not sure how far that'd go, nor how audible the result would be.

With regards to IMD, I'll leave this:
Quote:
Quote:
Originally Posted by Wikipedia
IMD is only distinct from harmonic distortion in that the stimulus signal is different. The same nonlinear system will produce both total harmonic distortion (with a solitary sine wave input) and IMD (with more complex tones).

Which suggests that a sine sweep (which gives you harmonic distortion curves) should provide plenty of data.

IMD is measured differently, but the mechanism producing IMD is the same as the one producing HD, just operating under different conditions.

Chris
Hi Chris!

As usual, Wikipedia has done a pretty fair job of explanation, but has missed/glossed over a thing or two.....

IMD and HD are different in structure. HD only contains frequencies in the harmonic series. IMD, however, can and does contain nonharmonic frequencies. Consequently IMD is generally audible at lower levels than many types of HD.

Wikipedia does not appear to be considering structure, which is kinda important in audio, don't you think?
Old 4th August 2020
  #227
Lives for gear
Oh, this thread's still going.

While IMD and HD are different, they are the products of the same physical processes (non-linearity in the driver's motor/cone/suspension) but with different input signals.
As a result, I don't think there's any great need to measure IMD.

I think, if we have an Accurate Cab Simulator(TM) that accounted for harmonic distortion, then if we measured it, it would also have IMD.

Chris
Old 4th August 2020
  #228
Quote:
Originally Posted by John Eppstein View Post
WANNA BUY A BRIDGE? I have several available throughout the country.... New York, San Francisco, Louisiana. You can make a lot of money on the tolls.....?

We would like speakers to be linear, but the truth is that only electrostatics really are, and only with a limited amount of low end.

Planars are coming close.

Both are lots of money and don't go very loud.

Any moving coil dynamic speaker is not going to be linear due to drag induced by the non-linear spring action of the surround and spider. And every one is non-linear in a different way, which is why speakers don't all sound the same.

The other enemy of linearity is The Laws of Physics, specifically, inertia and momentum, all that Newtonian stuff.

When a speaker, having mass, is moving in a particular direction it does not want to change. The suspension imposes a mechanical brake.

They do TRY to behave in a linear manner... But they fail.
Yes I agree. I came to this conclusion after I researched more on this subject. Not sure what this means for me using monitors and headphones for mixing. I guess it's all very non-lineair, funky, subjective. Which is no problem, or maybe I should say: I was never aware there was a problem.
Old 4th August 2020
  #229
Quote:
Originally Posted by chris661 View Post
Oh, this thread's still going.

While IMD and HD are different, they are the products of the same physical processes (non-linearity in the driver's motor/cone/suspension) but with different input signals.
As a result, I don't think there's any great need to measure IMD.

I think, if we have an Accurate Cab Simulator(TM) that accounted for harmonic distortion, then if we measured it, it would also have IMD.

Chris

Not at all. You may be able to get from one to the other using some kind of mathematical model, but implementation is a different issue. We simply don't have the compute power to do any of it near-real-time with any accuracy.

If you can live with playing through a poor model and then render the final model post-tracking, you might end up with a good rendition of a real guitar amp - without the exorbitant trouble and expense of using a $100 speaker and transformer-coupled power amp.



-tINY

Old 5th August 2020
  #230
Gear Nut
 
brainditch's Avatar
 

Quote:
Originally Posted by John Eppstein View Post
Jeez, a person who's actually wordier than me!

Even if you can't spell "instantiation"....
Yeah, well, you know what they say..."Wordiness is next to Dogliness", with or without autospell!
Old 6th August 2020
  #231
I don't think we want intermodulation distortion in the modelling of a speaker cab.
Old 7th August 2020
  #232
Quote:
Originally Posted by Raaphorst View Post
I don't think we want intermodulation distortion in the modelling of a speaker cab.

Speak for yourself. If its not there, it's not an accurate model, though.

As easy as it is for me to set up one of a dozen options with a mic, having a spooky-clean "cabinet" in a modeler is a nice option. If I want it to sound real, I'll use a real one.




-tINY

Old 7th August 2020
  #233
Gear Guru
 
monkeyxx's Avatar
When I use the Two Notes Torpedo Captor with a tube amp head, and an IR loader in the box, it's clearly a different sound than running through a cab in the room.

The good part is I find that particular rig very "sweet" sounding in its own way. It sounds some how more idealized than a miked up amp/cabinet with the same head. It's a pretty sound. Completely usable in a musical context.
Old 7th August 2020
  #234
Lives for gear
 

Quote:
Originally Posted by monkeyxx View Post
When I use the Two Notes Torpedo Captor with a tube amp head, and an IR loader in the box, it's clearly a different sound than running through a cab in the room.

The good part is I find that particular rig very "sweet" sounding in its own way. It sounds some how more idealized than a miked up amp/cabinet with the same head. It's a pretty sound. Completely usable in a musical context.

Same. Torpedo Live for me. Recently got a Cab M+ and running that straight out of my pedal board too.
Old 7th August 2020
  #235
It's cool now we have the choice. And I love it that we can improve our sounds and get new tones. This is good for art.
Old 17th August 2020
  #236
I have build a cabinet filter in Reason. I created a listening test, using 3 different sounding cabinets. Two using impulse responses, one using my own custom filter. Which one do you prefer?

Check it out yourself:
https://melodiefabriek.com/blog/scre...abinet-filter/
Old 19th August 2020
  #237
Running the CHOW hysterisis or tape in between and/or after the IR gives quite interesting results that seem to glue the high end to the lower frequencies, which imo is one of the biggest issues of sims.

Regarding this, I also got an idea for a new style of IR making and will return with it soon.
Old 19th August 2020
  #238
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Yuri Kogan's Avatar
 

Quote:
Originally Posted by Mordae View Post
Running the CHOW hysterisis or tape in between and/or after the IR gives quite interesting results that seem to glue the high end to the lower frequencies, which imo is one of the biggest issues of sims.

Regarding this, I also got an idea for a new style of IR making and will return with it soon.
But imagine what the real speaker/mic/pre/real tape would sound like then
Old 20th August 2020
  #239
Quote:
Originally Posted by Yuri Kogan View Post
But imagine what the real speaker/mic/pre/real tape would sound like then
I wasn't suggesting this is something you want to do in real life. The plugin just has a really good way of making high frequencies feel a part of the lower ones, which is a big issue with fuzz sounds usually.


Attached is the idea that I had. Should be pretty balanced and focused!
Attached Files

Aaltotarha_Waterfront.wav (62.2 KB, 72 views)


Last edited by Mordae; 20th August 2020 at 12:39 PM..
Old 20th August 2020
  #240
Lives for gear
 

I see these long threads on cab IR's - modellers - Amp sims' ....

Painstaking analysis and comparison.

OK for piano, drums, orchestra sometimes you have to use the rubber version because they're huge instruments.

But for guitar the real deal is so straight forward .... grab a Fender Princeton (or whatever), decent pedal board and a SM57 and your 99% there without the need for anything that goes in the night!
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