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I'm recording a guitar to my DAW. It's a clean signal. Then I apply an amp and Impulse Response signals I like. I heard that IR's should be applied after amp. What about effects like chorus, flanger, reverb etc. Should I apply them after or before IR?

Should it go clean signal -> amp -> IR's -> effects

or:

clean signal -> amp -> effects-> IR's

I noticed that when I apply effects before IR's then things like reverb and chorus last longer. That's probably because the IR is applied on all the signal affected by reverb and chorus and it becomes kind of overwhelming then.

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  • What effect are you doing with the impulse responses? Reverb? Does the thing, whatever it is that you call "IR", have a dry/wet control? Impulse responses can be used to reproduce linear systems like rooms, reverbs and equalization curves. To some degree, some aspects of amplifiers and speaker cones, but not their non-linear properties. If your "IR" means room acoustics simulation, for simulating a mic'ed amp in a room, I guess you need to adjust a dry/wet control to get more of the direct dry signal and less IR'ed signal in the mix.
    – piiperi Reinstate Monica
    Jan 1, 2019 at 16:08
  • I use one of the IR's from: Free Redwirez IR Library • Marshall 1960A • Celestion G12M-25s My convolver has dry/wet knob and I turned I set it to 100% wet. But I don't think that's the case here. Let's presume there are same settings in both cases I mentioned above. Is there some kind of a rule how to do it properly in a chain? Maybe someone who has already done it will share some knowledge with me cause I'm newbie.
    – Raven322
    Jan 1, 2019 at 16:16
  • I guess the Marshall and Celestion things are supposed simulate an amp and a mic'ed speaker - in a cabinet, in a room, recorded with a mic? So essentially it's an amp simulator. What is the "amp" you're talking about then, if the whole signal goes into another amp simulator - is it just a preamp simulator?
    – piiperi Reinstate Monica
    Jan 1, 2019 at 16:22
  • These impulses are sampled cabs. They were recorded with different microphones in a different positions. Just like you said. My guitar signal goes to a plugin in my daw where I can set input and output level of this signal and add effects like reverb, flanger etc. I'm amplifying the signal with overdrive effect also. I'm kind of lost. What in all of that can be described as "amp?" overdrive? And yes I'm using guitar amp simulator. That's the plugin I'm talking about.
    – Raven322
    Jan 1, 2019 at 16:52
  • I think that input signal knob is treated as a preamp and output signal knob can be treated as an amp. Am I right?
    – Raven322
    Jan 1, 2019 at 16:59

1 Answer 1

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The rule is: arrange the signal chain in the order you would in real life.

Each of the software-based processing components performs the task of one or more physical devices or components.

Convolving a signal with an impulse response recorded from a (linear) signal processing system (or component) such as a reverb effect, or an acoustic room, corresponds to running the signal through the actual system (or component) from which the impulse response was recorded.

As far as I understand, your question is, "In which order should I connect these things in a signal chain: (1) preamp, (2) effect, (3) power-amp, (4) cabinet? Should I put my effects between the preamp and power-amp, or should I run the cabinet microphone's signal through the effects?" This question could be answered just as well in a purely "real hardware" situation, where you only have actual physical hardware. How would you connect the components? You have to clarify to yourself the conceptual role of each of your software components.

(Theoretical mumbo-jumbo. If the components you call "effects" are linear and time-invariant, i.e. if they don't add any nonlinearities like distortion or modulate their parameters over time, then in theory, the order of processing should not matter, because convolution with an impulse response is a linear time-invariant system. And linear time-invariant systems can be connected in any order without affecting the final result. But if the effects are nonlinear or time-variant, i.e. if they add nonlinearities to the signal, or if they modulate their characteristics over time, then the order of processing does matter in theory. Whether any of this matters in practice however, is a different question.)

If the amp simulator that you imply is only used as a preamp (for overdrive/coloration) also includes cabinet simulation, then you are virtually running your signal through two cabinets in series. Which most probably sounds bad.

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  • Thank you for you answer. How do I know which effects are linear and which of them are not? Like among the most popular like chorus, reverb, flanger, phaser, delay.
    – Raven322
    Jan 1, 2019 at 18:04
  • You can treat EQ, reverb and convolution as linear (though there are special cases of colorizing or "vintage" EQ plugins). Anything that compresses or otherwise distorts the signal is non-linear. Chorus might be linear but not time-invariant. But really, arrange the components in the order you would in real life.
    – piiperi Reinstate Monica
    Jan 1, 2019 at 18:12
  • Ok, I checked and this is how my signal chain looks like: Guitar clean signal goes to audio interface then to DAW, then I add cab simulator vst, that vst also has pedal effects and I can manipulate preamp knob as well as power amp knob there. Then I turn off the cabinet that is built in into that vst and then the boosted signal that leaves this vst meets convolution with IR's from real cabinets. Is it good?
    – Raven322
    Jan 1, 2019 at 18:13
  • That's probably good. Two cabinets in series is not necessarily wrong, because in pop music, anything goes. But having a clear conceptual model of the signal chain helps you control what's happening. There are people who don't understand anything and just click click click away until it sounds good. :)
    – piiperi Reinstate Monica
    Jan 1, 2019 at 18:16
  • I always try to understand things as deep as it is possible and that's why I'm asking. As I think about these IR's I got I treat them as cabinets itself. So they should be and sound the best at the end of the chain, just as cabinet (speaker) is. Am I right? Thanks for your time piiperi :) I really appreciate it.
    – Raven322
    Jan 1, 2019 at 18:18

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