IRs and Cab Sims

[Grandy]

What do they do or are supposed to do? Iridium seems to appear everywhere these days. Is it or others like it worth their hefty price tag? Tech21 products have been around for some time. I'm happy with my Sansamp though it's not perfect by any means. Guitar Rig software is nice too.

I'm more interested in recording than live applications. What do you think of the new stuff compared to the old? Experiences?

 

[bgmacaw]

Impulse Responses are a measure of the response of a speaker, cabinet, mics and room over time. This is different from the old, EQ based, cabinet sims. So, you get a different sound if, for example, the IR uses close-in mic vs the close-in plus a room mic or just a room mic. Speaker response can vary a lot too, for example a 4x12 Vintage 30 cab vs a 6x9 offset speaker cab. Time also captures how these elements interact.

The price tag doesn't have to be hefty. Hotone, Joyo, Mooer and Nux have some good IR loading options. As for IR's themselves, I've been mostly using the ones from Ownhammer or York Audio.

 

[Grandy]

I've watched Mike Hermans' Nux demo a few times. I really wanted to like it. I've tested it through a small amp at a shop that sells them. I don't here it. Maybe it's just me and my ears.

I liked how the DSM & Humboldt Simplifier sounded on Andertons' demo but I don't believe I could here the difference between an old style cab sim and these new IR devices in a musical context (meaning a recording of a guitar in the whole mix).

I think we often get confused about guitar sounds when the context changes. I know I do. Standing in front of a loud guitar cab is one thing. Then there are the mics, the mixing console, effects, mastering, a few AD conversions and back and ....

Are they they selling snake oil? There's always a little bit of that in marketing isn't there? The most traditional vintage amp or reissue loads of mojo we can't explain, right?

Can you here the difference? Convince me.

 

[bgmacaw]

Can you here the difference? Convince me.

I'll try to record some stuff tonight for you, my Monoprice 5w into the Hotone IR Cab. Most of the tracks I record for the weekly Twanger Central tracks here use this combo.

The important thing with IR's is that they will sound best live going into a FRFR amp or PA system. Going into a regular guitar amp will have that amp's own characteristics mixed in and they may not match up well.

 

[Guitarteach]

I've watched Mike Hermans' Nux demo a few times. I really wanted to like it. I've tested it through a small amp at a shop that sells them. I don't here it. Maybe it's just me and my ears.

I liked how the DSM & Humboldt Simplifier sounded on Andertons' demo but I don't believe I could here the difference between an old style cab sim and these new IR devices in a musical context (meaning a recording of a guitar in the whole mix).

I think we often get confused about guitar sounds when the context changes. I know I do. Standing in front of a loud guitar cab is one thing. Then there are the mics, the mixing console, effects, mastering, a few AD conversions and back and ....

Are they they selling snake oil? There's always a little bit of that in marketing isn't there? The most traditional vintage amp or reissue loads of mojo we can't explain, right?

Can you here the difference? Convince me.

Testing through a small amp, means you just heard a small amp. PA or studio monitors are their target.

I use cab IRs on guitars in my DAW and they certainly add an authentic and very recognisable natural ambience to a guitar track. You can hear the cone/s of the speaker as if its there. The tools to use and make IRs are often built in the DAW and you can find free IRs to try them out. Def. not snake oil, but I suspect many are misused into guitar amps.

I have an AC30 cab IR I use a lot as it really gives an ‘in the room with you’ sound.

Our band is recording a lot in lockdown. I have also made acoustic guitar IRs of our instruments so we can make the piezo recordings match the microphone tone. Pretty good results considering and allows us to get great sounds in less than ideal remote situations.

 

[codamedia]

What do they do or are supposed to do?

They simulate the sounds of cabinets, speakers and microphones. It has many advantages over micing a cabinet on a stage or in a studio.

• Less live mics on a stage
• Ability to use a multi-mic setup at various distances rather than be forced into a close mic position.
• They allow modelers and profilers to be used direct to the console... no amp needed at all.
• Easy to experiment in the studio and live with various cabs/speaker/mics... without hauling around dozens of cabs/speaker/mics. This is also a rabbit hole if you are not careful.

Iridium seems to appear everywhere these days.

Iridium is just an amp sim/modeler that also has a cab sim / IR loader in it... but that's how amp modelers work. Helix, Fractal, Headrush, BOSS, etc... etc... they all do that.

IMO, Two-Notes leads the way with Cab Sims as their IR's are dynamic, just like working with real cabinets and mics.
Ownhammer, 3-Sigma, and many others offers static IR's.... which are a snapshot of a given setup. They work great as well, but for a different sound you change the IR.

EG: With a dynamic IR you move the mic (and change tone) by moving the virtual mic. With a static IR you move the mic by loading a different IR that has the mic baked into that position.

Tech21 products have been around for some time. I'm happy with my Sansamp though it's not perfect by any means. Guitar Rig software is nice too.

All of those have cab sims. The older products are just an analog circuit simulating the tone, IR's and Modern cab sims go much further. But they all work fine to varying degrees.

 

[klasaine]

Lotsa great responses here. I'll just add that ultimately, IRs in conjuction with a load box are just another tone tool. And a pretty versatile one at that.
I mic amps, I use a modeler (Iridium), I use software amp sims and I use IRs (2-Notes Cap X).

Here's a personal scenario ... I have two Dr. Z heads that are in the Vox camp (Carmen Ghia and Mazerati). When I really really need an AC15 or AC30 tone, I use one of those heads and one of the several 2-Notes Vox 2x12" cab IRs. Sounds great and way more 'Voxy' than micing my non-Vox cabs. *Iridium Vox (Chime) sim is also xlnt!

Here's another ... I don't have a 4x12 cab anymore but I do have a non MV Plexi clone head. There's a bazillion 4x12 IRs out there - every era, every spkr combo, closed back, 1/2 open, slant, straight, Mesa, Orange, Marshall, Laney, Suhr, etc.

Using IRs w/a load box is kind of a no brainer for modern, home recording.
To reiterate - they're just another tool.

 

[Grandy]

Thanks for your input y'all. I guess I'll have to try some of the new tech at some point. The problem is that it's a lot harder to estimate whether you like it than checking out an fx pedal, amp or guitar. You never really know until you try it in your own set up.

I guess I should trust my own ears. It's good if it sounds good. I'm pretty happy with my set up at the moment. For some things the virtual gear in my computer are fine. I can endlessly change the sound afterwards. And sometimes the Sansamp is ok too. I only wish I had a nice spring reverb on my computer. Maybe when I update the computer and the DAW.

The key for me seems to be the price quality ratio. I don't want to play 500% for 5% improvement (which I'm not sure I can here) in sound.

 

[swervinbob]

I’ve tried not to go too far down the rabbit hole with ir’s. I started with Ownhammer and have mostly used just them. And they come with so many mic combinations it can seem overwhelming. You just need to learn how they label everything. I mostly just use the OH1 mix, which is just a 57 and 121 mix. They’re labeled OH1-00 which is the brightest mix and then you get a bit darker as the number rises (01, 02...) sometimes I’ll mix the brightest and a darker mix. Just depends, but I usually just have one or two from each cab loaded I don’t get too crazy thinking I need 5000 mic mixes.

I’ve got a Two Notes Captor and have Wall of Sound which is Two Note’s ir plugin. I’ve messed with it a little, but I’m kinda lazy and already know what I like so I just grab an Ownhammer cab and go with it. But it sounds great also.

Recording with an analog cab sim can be just fine, but with impulse responses you can use the same amp (or amp model) and guitar, click a mouse once or twice to load a different cab, and put another track down with a different sound.

 

[Digital Larry]

Impulse Responses are a measure of the response of a speaker, cabinet, mics and room over time. This is different from the old, EQ based, cabinet sims.

To get slightly pedantic for a moment...

Signals and filters can be represented in time domain or frequency domain. Mathematical transformations can be made between the two. I consider them equivalent. e.g. a sine wave is a single vertical line on a frequency chart. Yes I studied and practiced EE and the "impulse response" of a circuit is something we all learned 40 years ago as representing the essential character of linear electrical circuits as well as mechanical systems such as the pendulum or a weight suspended from a spring (some very simple examples). A loudspeaker is much more complicated than those things but the same concepts apply.

Long ago I measured an H&K Red Box and found it to be a second order low pass filter with a peak around 2.5 kHz. With analog components that's fairly easy to accomplish with a single op amp and about half a dozen other parts. It doesn't give you the detail of a real speaker's many ups and downs, so the approximation is only "sorta". However, that circuit does have an impulse response and if you wanted to have an IR that sounds like an H&K Red Box, it's just as easy as anything else.

Digital impulse responses vary in the number of samples they have. More samples allows more detail to capture all those little squiggles you see on frequency response charts. I can't recall the exact relationship, one to one, one to two, but it's something like that.

I'm not sure I get the concept of a "dynamic" impulse response though... in the end it's a table of numbers that you convolve your signal through. https://en.wikipedia.org/wiki/Convolution

 

[SRHmusic]

...
I'm not sure I get the concept of a "dynamic" impulse response though... in the end it's a table of numbers that you convolve your signal through. https://en.wikipedia.org/wiki/Convolution

I'm guessing that dynamic impulse responses would be useful only for things that vary with signal content, like speakers or transformers that could saturate and have different responses at different signal levels. These should have some memory effects, as well. In other words they're "non-stationary" systems. There are probably a lot of ways to attempt to models these things, requiring more or less processing power.

I get how IRs sound for recording, but I think there's a fundamental problem in a live performance space. A PA or FRFR interacts differently with the room than an amp speaker cabinet. (It's like an impedance matching problem.) Perhaps in a huge venue it would sound like a mic'd amp. In a small venue the ones I've heard sound like a recording of an amp being played through the PA, as if the amp is in a completely different room (which is actually the case, effectively).

 

[Digital Larry]

I'm guessing that dynamic impulse responses would be useful only for things that vary with signal content, like speakers or transformers that could saturate and have different responses at different signal levels. These should have some memory effects, as well. In other words they're "non-stationary" systems. There are probably a lot of ways to attempt to models these things, requiring more or less processing power.

I don't know how things are done in real products, but strictly speaking, IRs and convolution cannot model distortion or compression or modulation (level or time dependent behavior).

 

[SRHmusic]

I don't know how things are done in real products, but strictly speaking, IRs and convolution cannot model distortion or compression or modulation (level or time dependent behavior).

Right, a single IR is by definition linear. Dynamic IRs sound to me like dynamic convolution where a different IR is used under different conditions. That might still only capture tone like changes, not things like harmonic distortion from compression unless the time frames are very short for when IRs are selected. This seems less like convolution and more like real time modeling. Volterra series make more sense here to me, but I've never played with these enough to see how it works out for audio. (I've used these things more for control applications, model estimatation.)

Some discussion here, selected quotes, not sure how accurate this discussion is(!). It would be great to find some demos of different approaches and their limitations.
https://dsp.stackexchange.com/questions/34355/dynamic-convolution-vs-volterra-series

"A flavor of dynamic convolution ... has a different impulse response associated with each range of instantaneous input."

"So, we monitor the input, convolve pulses depending on their amplitude and in the end we some everything together as if there is a set of linear systems operating differently and the output simply swings across their output depending on the amplitude of the incoming pulse.

"Right, so, Dynamic Convolution --> Sum convolutions per impulse of different amplitude."

 

[USian Pie]

I installed a free IR loader DAW plugin to try with Reaper.

I recorded some tracks using the direct out from my amp. The direct takes a tap off the output to the speaker so it reacts a little to the amps’s output stage but it has no simulation of speaker characteristics. The normal direct out sound is what I’ve come to expect - harsh and bearing little resemblance to a mic on the speaker.

I applied a “Deluxe P12” model from Line6 to that direct sound and was very impressed. It would easily work in place of the mic’d speaker sound.

I also have a SansAmp Liverpool. While it gets rave reviews, the clean speaker-emulated direct sound from it has disappointed me. It still has that harsh overly-detailed direct quality. Putting the Deluxe P12 IR on a Liverpool track fixed that, too.

I’ve been real tempted by the Mooer Radar and Torpedo boxes just to have something that would work in real time.

 

[theBedroomRocker]

I record a lot using IRs and really like how practical and realistic it sounds. I'm a big fan of Torpedo Wall of Sound, but also got great results using other IR loaders. I've made a comparison using 7 Celestion IRs, which may be interesting for some looking into these:

 

[gonzo]

i bought a Strymon Iridium back in 2020, at the beginning of the pandemic.

immediately started work on a full length instrumental album, called "Elemental", that used nothing but the Iridium.

here:


my '82 60 watt Mesa Boogie Mark IIb head has not been turned on since.

i use York Audio IR's almost exclusively now,
after 3 years of experimenting with almost everything.

if my Iridium got stomped by an elephant today,
i'd buy a new one tomorrow.