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Cab IR manipulation plug-ins
Old 5th August 2019
  #1
Here for the gear
 

Cab IR manipulation plug-ins

Cab IR loader plug-ins usually have simple controls like volume, LP, HP, delay & panning. What features do you miss there? Changing the resonance frequency (bass) of the cabinet, parameters like the Kemper has (clarity, pick), transient shaping etc. What would you like to manipulate?
Old 5th August 2019
  #2
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don't know if possible or part of the IR but i'd like to bypass an IR often for a specific frequency range. but not really multiband processing, only like leave the bass frequencies untouched or as original. so lp/hp bypass parameter maybe a IR shift could also be useful. like taking the IR spectrum an transfer it up or down. could be done by normal pitching or this new way without changing the frequencies relationship (hard to explain).
Old 5th August 2019
  #3
Gear Head
 

What's missing are the non-linearities of the speakers themselves. All speakers produce distortion that varies in amount according to frequency and level. Impulse responses do not capture/reproduce this. I no longer use cab IR's for this very reason, but if an IR loader was capable of emulating this characteristic, I would use IR's because there are situations where it would be way more convenient.
Old 5th August 2019
  #4
GOR
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Quote:
Originally Posted by Superb View Post
What's missing are the non-linearities of the speakers themselves. All speakers produce distortion that varies in amount according to frequency and level.
I think that should be tested extensively though. When I tried to put an effect on a drumset, I played it back through my speakers and recorded it. Tested it with different speakers and volumes, but the resulting recordings of different volumes did not differ as far as I can tell. Though it was noticable that the used mic's characteristic changed when leaving its sweetspot.

Could also be that those non-linearities are totally negligible or I did something wrong
Old 5th August 2019
  #5
Gear Head
 

Quote:
Originally Posted by GOR View Post
I think that should be tested extensively though. When I tried to put an effect on a drumset, I played it back through my speakers and recorded it. Tested it with different speakers and volumes, but the resulting recordings of different volumes did not differ as far as I can tell. Though it was noticable that the used mic's characteristic changed when leaving its sweetspot.

Could also be that those non-linearities are totally negligible or I did something wrong
Sorry, I thought we were discussing guitar cab IR loaders, which in that context speaker distortion, or lack thereof is audible when comparing an cab IR with the speaker/mic/room it was created with.
Old 5th August 2019
  #6
GOR
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Quote:
Originally Posted by Superb View Post
Sorry, I thought we were discussing guitar cab IR loaders, which in that context speaker distortion, or lack thereof is audible when comparing an cab IR with the speaker/mic/room it was created with.
No please, I'm actually interested in this topic. I would love a cab IR plugin with realistic sound. But in my personal tests non-linearity didn't seem to have much impact. I'm a guitar n00b though XD Maybe someone could provide examples for comparison or even IRS captured to show the differences. So far all IR loader seem to load "single dimentional" responses and I thought they might have done research on that too.
Old 5th August 2019
  #7
Gear Maniac
Well, if you are talking about doing cabinet IR's recording direct with a tube amp, the reactive load is an essential part of the equation. Those "frequency/level nonlinearities" mentioned earlier are addressed there. I use the Suhr Reactive Load and get amazing results from my tube amps and IR's.

If you are just talking about guitar cab IRs coming from some sort of modelling device or plugin, how good they sound are going to be highly dependent on the quality of the amp modelling. Obviously some are better than others.

Then there is the plain fact that not all IR's are created equal. Some are amazing (Celestion's own IRs for example, or Ownhammer's IRs)... others are only so-so, and some downright suck.
Old 6th August 2019
  #8
Gear Maniac
Quote:
Originally Posted by Superb View Post
What's missing are the non-linearities of the speakers themselves. All speakers produce distortion that varies in amount according to frequency and level. Impulse responses do not capture/reproduce this. I no longer use cab IR's for this very reason, but if an IR loader was capable of emulating this characteristic, I would use IR's because there are situations where it would be way more convenient.
Speaker distortion is orders of magnitude less than the amplifiers' distortion (even from a clean guitar amp) and does not contribute meaningfully to the resulting guitar tone.

The two major sources of nonlinearity in a woofer is due to excursion and thermal limits. If you manage to audibly distort a guitar speaker, it will sound nasty and be destroyed in less than a minute.

"Cone break-up" is a misnomer for a phenomenon that occurs with just a few microvolts applied to the speaker. It is completely captured in an IR, and there's no need to "push" the speaker for "break-up." The pushing is instead pushing the amp.

There have been efforts to capture the Volterra kernels of guitar speakers, and it's brought about no audible improvement over IRs. All the involved experts agree on this, and it's evident in practice when IRs are captured and used appropriately.
Old 6th August 2019
  #9
Gear Head
 

Quote:
Originally Posted by dpsbb View Post
Well, if you are talking about doing cabinet IR's recording direct with a tube amp, the reactive load is an essential part of the equation. Those "frequency/level nonlinearities" mentioned earlier are addressed there. I use the Suhr Reactive Load and get amazing results from my tube amps and IR's.

If you are just talking about guitar cab IRs coming from some sort of modelling device or plugin, how good they sound are going to be highly dependent on the quality of the amp modelling. Obviously some are better than others.

Then there is the plain fact that not all IR's are created equal. Some are amazing (Celestion's own IRs for example, or Ownhammer's IRs)... others are only so-so, and some downright suck.
You are correct, although for clean sounds on an amp with negative feedback it matters less, the more NFB is used. The NFB is trying to maintain a constant voltage versus frequency across the output of the amp, something that is very easy with a resistive load and imperfect with a reactive load. The more NFB we use, the closer we can get to lowering distortion and flattening the frequency response.

But once you begin to overdrive the output section, the negative feedback loop is broken and can not reduce distortion and frequency response variations - the amp reacts more to the load for clipped signals, just like an amp that does not use negative feedback. This is where a reactive load is of the greatest benefit in using IR's. We can get a bump in the low end and a gentle rise in the treble, like a real speaker.
Old 6th August 2019
  #10
Gear Head
 

Quote:
Originally Posted by yeky83 View Post
Speaker distortion is orders of magnitude less than the amplifiers' distortion (even from a clean guitar amp) and does not contribute meaningfully to the resulting guitar tone.

The two major sources of nonlinearity in a woofer is due to excursion and thermal limits. If you manage to audibly distort a guitar speaker, it will sound nasty and be destroyed in less than a minute.

"Cone break-up" is a misnomer for a phenomenon that occurs with just a few microvolts applied to the speaker. It is completely captured in an IR, and there's no need to "push" the speaker for "break-up." The pushing is instead pushing the amp.

There have been efforts to capture the Volterra kernels of guitar speakers, and it's brought about no audible improvement over IRs. All the involved experts agree on this, and it's evident in practice when IRs are captured and used appropriately.
I'm not talking about audible speaker distortion caused by pushing a speaker to it's limit. I'm referring to the presence of harmonics generated by the speaker at operating levels well inside the ratings of the speaker. Thickening, not clipping.

Here's my example for you:

Stock Princeton Reverb amp with the exception of a switch to allow for -2dB (stock) or -4dB of negative feedback, and a Celestion G10 Greenback (30W) speaker.

The graph below is THD vs frequency from 80 - 300hz. Amp controls were set to flatten the frequency response so that equal power vs frequency would be applied to an 8 ohm resistive load. Level was set to drive the amp to 1.2W output (NFB -2dB). This allows for about 10dB of headroom. I did not readjust the drive when using -4dB, so those specs are at 0.8W.

Distortion figures at 100hz

-2dB NFB:
ORANGE - Resistive load, measured at output - ~0.8%
BLUE - Speaker load, measured at output ~1.4%
BROWN (very top) - Miced speaker ~8.5%

-4dB NFB
GREEN - Resistive load, measured at output - ~0.8%
PINK - Speaker load, measured at output ~1.3%
GOLD - Miced speaker ~6%

This is not limited to guitar speakers either. For example, Neumann KH120's have close to 5% THD at 50hz/100dB SPL. (-25dB below fundemental) Source: http://www.neumann-kh-line.com/neuma...pen&term=THD+N
Attached Thumbnails
Cab IR manipulation plug-ins-thd-comparison.jpg  
Old 6th August 2019
  #11
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Quote:
Originally Posted by leksi View Post
don't know if possible or part of the IR but i'd like to bypass an IR often for a specific frequency range. but not really multiband processing, only like leave the bass frequencies untouched or as original. so lp/hp bypass parameter maybe a IR shift could also be useful. like taking the IR spectrum an transfer it up or down. could be done by normal pitching or this new way without changing the frequencies relationship (hard to explain).
The frequency specific bypass is definitely possible. Would be great for before / after comparisons. I was also thinking about the spectrum transfer you mentioned. This way you could change cabinet size (in terms of resonance) to sound between 4x12, 2x12 and so on.

Quote:
Originally Posted by GOR View Post
No please, I'm actually interested in this topic. I would love a cab IR plugin with realistic sound. But in my personal tests non-linearity didn't seem to have much impact. I'm a guitar n00b though XD Maybe someone could provide examples for comparison or even IRS captured to show the differences. So far all IR loader seem to load "single dimentional" responses and I thought they might have done research on that too.
I agree. We've done extensive tests with IR capturing in the last weeks. The non-linearities don't seem to have much of an influence. However, I've heard that argument of a lack of depth with IRs from a lot of people. But I believe the way of capturing the IR is absolutely important. Our latest experiments are barely distinguishable from the mic'd recordings.

Quote:
Originally Posted by dpsbb View Post
Then there is the plain fact that not all IR's are created equal. Some are amazing (Celestion's own IRs for example, or Ownhammer's IRs)... others are only so-so, and some downright suck.
Agreed. I often hear that there are a ton of different cab IRs out there. But if you are looking for quality stuff it comes down to only a few companies. Have you ever compared normal load boxes (like the two notes) with reactive load boxes (like your Suhr)?

How important is it to you (all of you) to mix different IRs to get a new fresh sound combination?
Old 6th August 2019
  #12
Gear Maniac
Quote:
Originally Posted by Superb View Post
I'm not talking about audible speaker distortion caused by pushing a speaker to it's limit. I'm referring to the presence of harmonics generated by the speaker at operating levels well inside the ratings of the speaker. Thickening, not clipping.

Here's my example for you:

Stock Princeton Reverb amp with the exception of a switch to allow for -2dB (stock) or -4dB of negative feedback, and a Celestion G10 Greenback (30W) speaker.

The graph below is THD vs frequency from 80 - 300hz. Amp controls were set to flatten the frequency response so that equal power vs frequency would be applied to an 8 ohm resistive load. Level was set to drive the amp to 1.2W output (NFB -2dB). This allows for about 10dB of headroom. I did not readjust the drive when using -4dB, so those specs are at 0.8W.

Distortion figures at 100hz

-2dB NFB:
ORANGE - Resistive load, measured at output - ~0.8%
BLUE - Speaker load, measured at output ~1.4%
BROWN (very top) - Miced speaker ~8.5%

-4dB NFB
GREEN - Resistive load, measured at output - ~0.8%
PINK - Speaker load, measured at output ~1.3%
GOLD - Miced speaker ~6%

This is not limited to guitar speakers either. For example, Neumann KH120's have close to 5% THD at 50hz/100dB SPL. (-25dB below fundemental) Source: http://www.neumann-kh-line.com/neuma...pen&term=THD+N
I could ask a lot of questions about your testing... But ignoring all else, your graph immediately jumps out as unrealistic. No speaker THD response I've seen shows that kind of a smooth and flat response from 80-300Hz. Something ain't right, I suspect some kind of mistake in measurement.
Old 6th August 2019
  #13
Gear Addict
 
grannis's Avatar
Quote:
Originally Posted by forwardaudio View Post

How important is it to you (all of you) to mix different IRs to get a new fresh sound combination?
I always use dual IRs - typically starting with a classic combo like a 57 and 121 on the same speakee, but then randomly trying others to see if it sounds better or worse until I get bored!

Having a tool that would automatically give you something like an audio "slide show" of pairs IRs on a clip of guitar, and rate each combo while it is playing wold be very cool
Old 7th August 2019
  #14
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Quote:
Originally Posted by grannis View Post
I always use dual IRs - typically starting with a classic combo like a 57 and 121 on the same speakee, but then randomly trying others to see if it sounds better or worse until I get bored!

Having a tool that would automatically give you something like an audio "slide show" of pairs IRs on a clip of guitar, and rate each combo while it is playing wold be very cool
Sounds like Tinder for IRs . Very nice!
Old 7th August 2019
  #15
Gear Maniac
Quote:
Originally Posted by forwardaudio View Post
Agreed. I often hear that there are a ton of different cab IRs out there. But if you are looking for quality stuff it comes down to only a few companies. Have you ever compared normal load boxes (like the two notes) with reactive load boxes (like your Suhr)?

How important is it to you (all of you) to mix different IRs to get a new fresh sound combination?
I first dipped my toes into the tube amp direct via IR waters with a Radial Headload Prodigy. It did not sound good to me... at all... no matter what I did. Thankfully I bought it somewhere that has a generous return policy. I bought it thinking I could kill two birds with one stone and use it as an attenuator live as well.

So I broke down and splurged for the Suhr Reactive Load. It put an immediate smile on my face using Ownhammer IRs. I since have invested in some of the Celestion IRs and pretty much use those exclusively now.

I typically track just using a basic single IR but at mixdown I will switch it to a dual stereo IR. Usually a ribbon/dynamic or a ribbon/LDC combo panned mostly hard left/right and one side with a teeny tiny bit of a delay. Makes a big open sound if that is your goal.

I just use NadIR... free and gets the job done quickly and easily.
Old 8th August 2019
  #16
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Yuri Kogan's Avatar
 

Quote:
Originally Posted by yeky83 View Post
Speaker distortion is orders of magnitude less than the amplifiers' distortion (even from a clean guitar amp) and does not contribute meaningfully to the resulting guitar tone.

The two major sources of nonlinearity in a woofer is due to excursion and thermal limits. If you manage to audibly distort a guitar speaker, it will sound nasty and be destroyed in less than a minute.

"Cone break-up" is a misnomer for a phenomenon that occurs with just a few microvolts applied to the speaker. It is completely captured in an IR, and there's no need to "push" the speaker for "break-up." The pushing is instead pushing the amp.

There have been efforts to capture the Volterra kernels of guitar speakers, and it's brought about no audible improvement over IRs. All the involved experts agree on this, and it's evident in practice when IRs are captured and used appropriately.
Really?!
Old 9th August 2019
  #17
You guys do know that the best tool for manipulating an IR is the DAW you use every day right? Load it into a track, go to town with whatever you want, export it again, use it in whatever IR focused application you want.
Old 9th August 2019
  #18
Gear Head
 
Cirrus's Avatar
 

Re "speaker breakup" in guitar cabs... I think it typically manifests itself in guitar speakers as compression. A broad rule of thumb is that they start to compress more once they get above about half their power rating. I've very situation dependent, though. Alnico tends to compress more than Ceramic, for example. And some classic amp/speaker combos will basically never get there. For example, a Mesa into a 4x12 of Vintage 30s in most situations will get nowhere near the ~120 watts that would represent half the power handling of those speakers. Whereas an AC30 into two Alnico Blues will be pushing well into speaker compression before the amp starts to break up. And, indeed, if anyone's ever compared an AC30 with blues to an AC30 into more powerful ceramic speakers, you'll notice that while you can get louder cleans with the 100db/w Blues than 97db/watt greenbacks, if you crank the volume all the way up the volume is about the same because by then the blues are compressing heavily whereas the greenbacks still have something to give.

So that's my two pence - the level dependent non-linearities of a speaker cab typically manifest as compression rather than audible distortion. And for that reason, they are more easily felt than heard by a third party, because only the person actually playing can feel the difference between what they're putting into the guitar and what they're getting out of the speaker.
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