speaker + Cab models vs impulse response? Help!

Discussion in 'Digital & Modeling Gear' started by Elwin Ransom, Jan 1, 2020.

  1. Elwin Ransom

    Elwin Ransom Member

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    This is probably a bit of a noob question, but I've been running an older modeler for years (POD X3 Live) and it was made before digital models of impulse response were really a thing. Lately I've begun to hear a lot about loading impulse responses into your rig (Ox box or other reactive load boxes, Helix, Kemper etc.). I understand that they're a digital recreation of how a speaker interacts with a given amp but I'm wondering how that differs functionally from speaker and cabinet models. When I swap out different speaker and cabinet models on my X3 Live, isn't that essentially the same as choosing different impulse responses? Just looking for a little clarity on what we're all actually talking about.
    bonus question: How do you choose an impulse response? ie: how do we label them? (If we simply label them with the name of the speaker being modelled, isn't that just the same as cabinet models? Hence the confusion for me.)
     
  2. AuntieDiluvian

    AuntieDiluvian Member

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    Yes - from a practical perspective it's two different ways of saying the same thing. There are some differences in the tech used to achieve them, but that really doesn't matter in terms of how you use them.
     
  3. John Mark Painter

    John Mark Painter Member

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    Different technology.

    How to choose them?
    You are using a real specific cab with actual mics in specific positions run through outboard gear/post processing etc to get a specific tone from that cab.

    It’s a snapshot of that setup.

    Different IR vendors are creating different tones based on their taste and recording techniques. You have to find what works for you
     
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  4. Lele

    Lele Supporting Member

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    Old modelers too, mostly use impulse responses to simulate speaker/mic behavior: the difference is the lower resolution of old modelers.
    Let's use an equalizer as example, since at the end an impulse response (convolution) is like an equalizer with many bands.
    A current modern modeler can manage an equalizer with one thousand bands, so it means that you can adjust fine details of your sound getting more clarity, killing harsh frequencies, like a real speaker.
    The old modelers had small eq capability, like for example 10 or 20 different bands only. So it means that you had much less possibilities to adjust your sound; reducing harsh frequencies meant reducing also some good tone characteristics and at the end you couldn't really simulate properly the behavior of a good speaker/mic.

    Then if we add that today you can even try to use far field IRs to simulate better what our ears typically perceive, you'll understand that the evolution of current IR convolvers is really a step forward.
     
  5. dspellman

    dspellman Member

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    Try running something like a Two-Notes Torpedo C.A.B. (newer version has an /M tacked on). Used, these can be had for $150. It provides some spectacular cabinet IRs differently from most, and it provides tube power amp sims as well. You may find that the combination of that and your X3 is capable of challenging a lot of the high-priced spreads.
     
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  6. voss451

    voss451 Member

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    I use a Pod X3 with a Mooer Radar ir loader pedal and it improves the sound 100%. It's definitely worth it to get a 2nd hand ir loader vs buying a whole new modeller.
     
  7. aleclee

    aleclee TGP Tech Wrangler Staff Member

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    I like to name them Suzanne 1, Suzanne 2, etc. ;) Seriously, you name them whatever works for you.
     
  8. Elwin Ransom

    Elwin Ransom Member

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    What confuses me is that newer modellers (like a helix) use both IRs and cabinet+speaker models so there must be some functional difference. Those cabinet+speaker models also include mic choice and placement so I’m still a little foggy as to how IRs figure into the equation and how to go about using them. Many of the YouTubers out there throw around IRs like we all know what they’re talking about but I can’t help wondering why they use them if they’ve already set up a good sounding cabinet+speaker model and adjusted the mic settings to taste. Sounds like IRs are just another level of tweakability that is currently beyond the discernment of my ears?
     
  9. Elwin Ransom

    Elwin Ransom Member

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    I appreciate the humour but I meant, how do we label them in a way the meaningfully differentiates their function from a speaker model? How do we begin to talk about them and their characteristics in a concrete way (other than some subjective descriptor like “warm” or “spongy”)? Are they measurable in some way?

    Am I over thinking this and should just spend more time playing guitar?!
     
  10. KenG

    KenG Member

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    Helix cab mics allow for distance not placement on the speaker. IMO adding that extra dimension would be an improvement in cab sounds.
     
  11. Lele

    Lele Supporting Member

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    Why do we have one million od pedals?
    Why do we have thousands of different guitar amps?
    Because they have a different "flavor" (sometimes with little or no difference at all). The same can be said about billions IRs and stock cabs (that are anyway IRs).

    Yes and no.
    A good sounding speaker sim is almost the most important part of your tone (if we talk about most hi-end modelers that have finally solved the other missing detail till yesterday, that is the dynamic response), so imho it's fine to look for a good solution about it. And for this reason I'd really suggest to read the thread started by Jay Mitchell that I linked in my previous post.
     
  12. Deaj

    Deaj Silver Supporting Member

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    Guitar speaker(s) and cabinet are perhaps the most important (or influential) component of a guitar amplifiers sound. This is no less true in the digital domain. As already noted in responses to the OP the speaker emulation in earlier guitar amp/cab modeling platforms is similar to the speaker/cab/mic impulse response files used in current modeling platforms, generally speaking. Both are static EQ filters. The most significant difference is the number of frequency bands used to represent the speaker/cab/mic (resolution). The higher the resolution the more frequency bands, resulting in a more accurate representation of these elements. Todays impulse responses are a huge improvement over earlier guitar cab emulations.

    An impulse response, in the simplest of terms (and as others have posted here), is a fixed, high resolution EQ. A frequency sweep impulse is sent through the speaker/cabinet to be emulated, powered using a neutral amplifier. That amplified impulse is captured with the microphone to be emulated, preferably through a neutral mic preamp. The impulse captured by the microphone records how the speaker/cab 'color' the frequency sweep impulse. This results in a static EQ with enough resolution to represent the sonic characteristics of the speaker/cabinet and microphone being emulated - this is the impulse response. Neutral mic pre and amplifier ensure that these components add as little of their own sonic characteristics as possible (or not, if one desires to have the sonic characteristics of one or more of these components captured and integrated into the resulting impulse response).

    As noted above a speaker/cab/mic impulse response is a static EQ filter. While they can emulate the sonic characteristics of a given speaker/cab/mic they In no way emulate the interaction between a guitar amp and guitar speaker/cabinet. This is true for earlier cab emulation as well. This interaction may be modeled but not within an impulse response file. These files contains no code, just static data.

    Regarding the naming of guitar cab impulse response files - ideally the file name will provide some basic indicators for cab make/type, speaker make/model/version, and microphone used in the capture of each impulse response (example: mesa_2x12_g12h30_sm57.ir). Such naming convention is necessary to organize impulse response files and so that one may easily identify the content of these files. Commercial cab IR libraries often contain more than 100 impulse response files so organization and quick identification are crucial.

    The relatively low resolution of the cab emulations in earlier modeling platforms limits the level of detail in said emulations, thus limiting the difference between, say, one 4x12 cab emulation verses another 4x12 cab emulation. Here, then, it might make sense to name such emulations something like... 4x12 #1, 4x12 #2, 4x12#3, etc. Simple choices, simple names.
     
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  13. burningyen

    burningyen Member

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    Helix cab sims are essentially IRs that are grouped by cab+speaker type. So when you’re selecting the mic distance you’re really just selecting a different IR shot at that distance.
     
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  14. therealjoeblow

    therealjoeblow Member

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    I was just going to post this after all the tldr responses.
     
  15. Elwin Ransom

    Elwin Ransom Member

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    Ok that really helps! Thanks so much for that explanation!
     
  16. cwlivingston

    cwlivingston Member

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    All PODs, even the first one, used impulse responses for the speaker + cabinet + mic sounds.

    They only used the term “speaker and cabinet modeling” (or whatever they said) because IRs were new (to them) technology and they weren’t 100% sold on it yet. But they had to choose between a static eq insert or the newer and more promising (but not quite great yet) IR technology, so for future development flexibility, they chose IRs.

    Don’t let “speaker and cabinet modeling” throw you. There was never really such a thing. It was always IRs. They’ve just gotten a lot better, especially in the last 5 years.

    Pete Anderson continued to use his POD 2 until very recently because he loved the Deluxe Reverb model, but as the IR technology improved over the years, he had L6 load newer cabinet IRs into the firmware. I don’t know why they didn’t make that available to all customers except they didn’t want to do anything to hurt sales of their newer PODs.

    But to be clear, your POD X3 has IRs. Just not great ones. Try bypassing the cab section and run into your DAW hosting an IR loader. There are good free ones. Redwirez offers a great free G12M set. You might be shocked how much better the X3 sounds with better IRS.
     

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