Guitar Cabinet Simulation with Impulse Responses Explained 

Amps would be 1/3 cheaper if they didn't insist on using that option nobody uses.

Damn! I KNEW I was doing something wrong! Finally.

I didn't see that coming lol

Thanks!!

how's that😢

FX Loop send is the simplest way to do it; you're bypassing the power amp section but if you don't generally push it hard enough for power amp distortion it probably won't matter.

MyThezoo I have an old Marshall SE100 (speaker emulator/load box) that i can plug the speaker output from my Marshall head (for example) into and then get a line signal to plug into my interface/DAW. The SE100 have separate outputs for the built in analog speaker emulated signal and a non emulated signal that can be used with IR´s etc inside the DAW and with the SE100 you dont need to have a speaker connected to your tube amp since its also a load box. This way you are also certain to get the sound of the whole amp and also completely silent recording as with a POD device or similar.

Still working on it! Fun stuff

unfortunately, I don't have a link... I have a folder full of all kinds of IR's mixed in. I think it is a rosen audio IR though.

+Sam Schmidthuber no, I prefer not to much of the time. (Sorry so curt, this was a pre-coffee Brian response 😂 )

I do occasionally use a thumbpick though. I just like the "feel" of the fingers. It's just how's I do's it! 😂

Wampler Pedals totally understandable! Like Brent!

Alan Angel I was thinking the same thing. The only mic that makes sense (and should be the standard) it's that ear doll used to record orchestral presentations.

Look for one that uses the highest convolution possible. Many of the cheaper ones have very small sample rates and are therefore lower quality sounding

Yes, and even worse... we BOTH do!! LoL - I still use SansAmp even while using my Eleven rack on other tracks.

​@@IFY0USEEKAY Great to hear that, lol. Though I have to say, the more I play with impulse responses with the PSA-1, the more I like it! I think the idea is to compensate for different "cabinets" with the "high" control...

Late response. The entire point of making an IR is to capture the frequency curve of a speaker cab. The video gets a couple of things wrong. The sine wave method sends a neutral sine wave across the frequency spectrum, which is useful cuz a sine wave is a single harmonic at a fixed level moving through the frequency spectrum which makes it easy to capture the IR. Putting it through the front of amp is NOT a good idea cuz you would run into preamp coloration and preamp distortion, which WILL change the tone. For best results, you want to generate the noise through a solid state power amp. This way you get pure output WITHOUT preamp coloration. Assuming the SS poweramp is NOT CLIPPING, you would be able to capture the sound of the cab perfectly.

Yes

I do have an older one about that.

You'd use pink noise.

Right, white noise and pink noise will show frequency response and is how many of the RTAs (real-time analyzer) work for EQing a room. But...mathematically it is easier (and arguably more precise) to run a chirp waveform like you hear in this video because the IR algorithm will know the mathematical function cos(wt^2) and thus be able to apply the inverse of it to extract the impulse response. You can read about the deconvolution operator if you want to know more.

Thanks for the explanation, that is logical, Captain, but what would be more scientific would be to use a spectrum of individual frequencies. I think I'm right in saying different frequencies will give a different result, so to us one very high pitched chirp is not going to be representative. If you use one frequency, it should be in the mid ranges.

Agreed, I stand corrected.

The majority of the tone comes from the speaker. If your amp sim has a removable IR, run it without the cab and see how it sounds. It's pretty terrible. IRs capture a digital snapshot of the speaker and uses it to filter the amp sound. It's VERY accurate.

Egnater into two notes captor, then into IR device then into mixer for better results of direct recording. I did a video on this a few weeks ago actually

Awesome! So direct out of the speaker out into the captor into a bluguitar blubox into the mixer? Hoping for a cheaper solution, but you get what you pay for. Thanks for the reply!

I understand you, but not everyone prefers it that way. Some popular IR’s are intentionally ran through guitar tube amps as a USP. The really interesting stuff is Kemper-esque profiling IMO.

Just kidding Brian. I enjoy these videos. Learning something new is always good. Especially when it’s about pedals and amplifiers.

Because the defining characteristic of any guitar sound is often the most overlooked one: the speaker. A lot of amps do have a di out with cab simulation tho if you want a cabless solution with no IR. But imo, built in cab sims don't compare to an actual loaded IR.

If it's an IR loader it's not analog by definition

@@GiacomoVaccari You're right. It's my bad. Didn't check what I wrote. I mean not analog but separate device with IR load capability. What I'm trying to say is this - you have something like Mooer Radar with bunch of IRs and a laptop with a DAW, IR loader and same IRs (same sample rate, etc). Is there any difference in sound?

@@Recovery_Station I don't know myself since I have little experience with IRs but one would assume the difference would be miniscule

It isn’t the amp itself generally, it’s the speaker cabinet, mic, room, and mic positioning. Some companies make “profiles “ which are sort of similar to what you are referring to however

@@wampler_pedals Hmm. Well I guess the big question is if I look at a graph of the impulse response of a certain amp and cab in a certain environment, would that not be replicable using only filters to basically EQ in the same frequency response?

Not exactly because there’s a “time” axis with IR’s, it’s sort of like a eq over a set amount of time. That eq changes during that time just like the mechanical device (the speaker cabinet). Also, the eq is quite extravagant, I’m not sure it could be done accurately with just some analog eq’s.

@@wampler_pedals Oh, well thanks for replying and answering my questions.

Thank you

Not only that but preamps themselves have all kinds of filters that affect all frequencies and in results when you want to use amp sim or analog gear, that you wouldn't pass through another preamp, will get colored by impulse more than it should. That's the reason many IR makers use solid-state power amps, although some use tube ones and get amazing results.

+NeZversTutorials yes, most good IRs are that way, however a quick google search will show people offering there IRs via a variety of ways, including the input. Like I said, some IRs are great, some suck horribly. Many factors involved. Keep in mind that I’m explaining this very basically, it’s not intended for someone who even knows what an IR is to begin with.

I just thought that would lead plenty people shooting in their own foot. BTW cheers from Latvia! ;)

see my comment below regarding this. It'll work, it'll just bring the suck.

yes! as if you mic the amp far away you'll get direct and reflected sound(reverb) as well.

basically the program that injects the sine sweep is the same that receives the captured sound.

Thanks. I understand the basic principle of recording the colouration of a signal then applying the difference profile to other signals. They were doing that with reverb profiles ages ago when I was still active in studio recording. What I mean is , where is the transient? As in an abrupt change in level if the injected signal is a sine wave, or a sweep of sine waves? What I'm wondering is; if the mathematical convolution routines in the IR software are somehow deriving what it estimates as the response to transients by extrapolation from the test sweep results or whether the word "Transient" is somehow misused here. I guess I'll have to go and dig amongst the techie articles...

KozmykJ I don't know but if consider the transient as "the component of high frequency within the a attack of a sound" you'll still be measuring frequency amplitude within the time variable. I'm probably not understanding your doubt; my lack of knowledge. I guess one could use the shotgun noise to convolute it trough.

Re-reading your reply I think I understand now. The abrupt change is done by the "instrument" (source) that you use; the amp or room only responds to that impulse. I guess

You can use IR’s several Different ways. If using your computer/DAW then yes you will get MUCH better results with some sort of interface, even if it’s an inexpensive one. They do make pedals which you can put IR’s on as well though.

It depends on how you are using them, but impulses themselves don't create latency.

NeZversTutorials I'm referring to using them in real time through a full range system ! Is there latency compared to using an analogue speaker sim ? Is there latency compared to a miked up cabinet ?

Impulse responses are partly used to replicate the natural latency of ones rig, the other part being timbre.

Greg Boland Depending on implementation, the latency might have a direct relationship to the number of 'taps' used by the discrete convolution integral. A 128 tap IR will have a delay of 128*Ts, where Ts is the sampling period (e.g: 1/48khz).

Brad Atherton i was about to say that...(no i wasn't...not enough smart...)

I'm prescribing you to 10 Valium per day for your Convolutions. Take 2 in response to your impulses.

+UmpO Rama no, it doesn’t work that way

Wampler Pedals I know, I know. A boy can dream though. Right? Is it an anaolg circuit and digital circuit thing? Just curious.

Like a profiler? kemper does that I believe

Then you have been missing a lot lately because couple developers have made their impulse loaders to do what you described - TSE audio (made also loader for 3 Sigma audio) and Kazrog done that first.

Well, you could take IRs with different poweramp volumes. As he said, it's just a snapshot of the current setup, amp, cab, speaker, mic, mic placement, even mic preamp and soundcard. With the right knowledge and tools you could probaply tweak the IRs to emulate that breakup or just make one from scratch (all digital signal processing is basically IRs) and you can most definitely add dynamic reaction there. Imo, while I absolutely agree that it's not perfect, it's just so damn convenient. Especially if you don't have a fancy cab/recording setup or just don't want to annoy your neighbours with a cranked amp when you get that idea for a song at midnight. Even EytschPi42, who has an isolated room with miced cabs uses a torpedo studio for most of his demos, because of convenience

@NeZversTutorials I can't find any information on there existing plugins to simulate non-linear aspects of speakers from those developers. Mathematically, only linear time-invarient systems can be modeled using impulse responses. It's impossible to capture non-linear information from an impulse.

@Uzmeyer They're definitely convenient! I personally like that I don't have to worry about things like mic placement when using them. Provided the impulses were captured by someone who took into account things like phase and placement of microphones, all that hard work is done for you already. Creative engineers will utilize the added flexibility of IRs to enhance their work and create much better recordings. But I just think it's important for people to realize what they can do and what they can't do with IR - understand the limitations and don't get caught up by hype. And the fact is, a lot of what we like about certain amps in certain situations is mathematically impossible to capture via an impulse response. What you said about taking IRs with different poweramp volumes wouldn't be enough to simulate breakup. Breakup and compression are impossible to simulate with impulse responses, because breakup and compression are not linear processes, and impulse responses can only capture linearities. I'd like to see a someone discuss these limitations, and maybe make a video showing the concrete audible differences of what can and cannot be captured by IR. Maybe Wampler could do it.

@Justin Satriano You are right, it's only LTI with IRs, i got something mixed up. Probaply thought about something like Volterra series, wich can do non linearity. Not sure if you could capture that though. Kempers for example im pretty sure also only capture IRs but you can change gain and so later, at least that's what im getting from the demos, but no idea what is actually happening there. My signal processing professor once even talked about simulating tube amps, gotta look if i can still find the notes, it's been a while. And yeah, a video about the possibilities and limitations would be great, people tend to get carried away with new&awesome tech to the point of using it for everything, even if the older tech is still better in some situations (like when recursive programming became a thing and suddenly everything had to be done that way). Also I believe you *can* theoretically capture everything mathematically, but for the time and effort you could probaply just buy a couple dozen great amp setups.

nope, Indiana. Kitty was off gallyvanting or something.

Hi Ricardo. That's because this video is 3 years old and in the meantime these links expired:) Rosen digital changed their name and website to Lancaster Audio. The link for free IR loader is lancasteraudio.com/pulse/ (they don't offer any cabs for free anymore) But RedWirez are offering free high quality IRs for a Marshall 1960. I'm using these and they sound amazing. redwirez.com/pages/the-marshall-1960a-ir-pack If you'll dig more on the internet you'll find a lot of free high quality stuff that is offered. Companies that are offering one product for free hoping they'll sale you more. Hope this helps

Pedro Martins Agreed... it's a game changer.

I'd love your Two Notes Torpedo Live too. Give it to me :D