IR Question

  • Thread starter Thread starter matttornado
  • Start date Start date
M

matttornado

Active member
What exactly is an IR (impulse response)? Is it just another name for a real pre-recorded amp simulation? How and why would I use them?
Are they primarily used for recording?

Thanks!
 
In the context of guitar talk it's just an EQ curve, usually that of a cab/speaker/mic chain. Mostly used when you want to use your amp without a cab, or when using a modeller and wanting to recreate a certain cab. Live and recording, pretty nifty stuff but takes a lot of messy about to get great results.
 
In layman's terms its a "pre recorded" guitar speaker.

To use them you need an IR loader. Lepou makes a good one for free called Lecab I think it is. You can use them different ways and with real amps too but these are what you need when using amp simulators. Guitars will sound like shit without an IR when using amp sims.

Theres millions of IRs available for free online if you dig. They're great honestly. Instead of having to swap speakers in a cab just click the button.

I've found some of the better ones are ones you pay for like official Celestion but "Gods Cab" was one of the more popular free ones back in the day. Was just a great capture of a Mesa cab iirc.
 
They’re great. I used to have a treated space with all kinds a mics and mic pres. I can get a better recorded tone with my Torpedo with waaaaay less effort.
 
There's a much more complicated explanation, but for most guitarist's simple purposes, it's basically a digital imprint of a guitar speaker/cabinet and mic recording chain. If you have the appropriate equipment, it allows you access to tons of cabinets, speakers, mics, mic preamps, etc, and takes the process of miking a cabinet out of the equation when trying to record, or sending something to a PA system. They have completely changed the way I play guitar at home over the past decade.
 
Good luck, it's a bit of a rabbit hole.

I'll add that you can achieve far better results creating your own over using commercial ones, due to the fact that every amp will respond differently to a given reactive load. Results using commercial IR's can sound good, but it's a crap shoot involving luck and patience. Custom made ones for your setup will truly represent your mic'd cab....but that's probably for another thread (y)
 
ZEN Amps said:
Good luck, it's a bit of a rabbit hole.

I'll add that you can achieve far better results creating your own over using commercial ones, due to the fact that every amp will respond differently to a given reactive load. Results using commercial IR's can sound good, but it's a crap shoot involving luck and patience. Custom made ones for your setup will truly represent your mic'd cab....but that's probably for another thread (y)
Click to expand...



100 percent truth here for sure. My two notes torpedo is completely different in response and feel when playing, or when reamping than when using a real cab and mic. Especially in the low end, I can’t get near the low end with Two notes as I can with my cab: the good kind of low end. That harmonicly rich build up that blooms like nothing else: impossible to get in my experience compared to a real cab. I assume it has everything to do with two notes fixed impedence load ( while it is a reactive load, that still doesn’t solve every issue.)
 
They are great for recording or sound reenforcement without putting a mic on a guitar cabinet. In that context, I think most people probably get better results than with an actual mic (I sure do, because the professional making the IR is much better than I am at mic'ing a cab).

A lot of folks try to use them for backline with a supposedly "full range" PA type cabinet, and that's where I'd say just use a guitar cabinet. The mic'd up sound is just different than what we're used to coming from a backline and it's just not particularly satisfying IMHO.
 
cardinal said:
They are great for recording or sound reenforcement without putting a mic on a guitar cabinet. In that context, I think most people probably get better results than with an actual mic (I sure do, because the professional making the IR is much better than I am at mic'ing a cab).

A lot of folks try to use them for backline with a supposedly "full range" PA type cabinet, and that's where I'd say just use a guitar cabinet. The mic'd up sound is just different than what we're used to coming from a backline and it's just not particularly satisfying IMHO.
Click to expand...

I don’t know about a “PA style cabinet”, but if you mean running directly to FOH, then yea that’s for sure a thing, and extremely popular and clean. It’s much better (at bigger venues) than having a cab on stage blasting through the FOH killing the sound of the band as a whole, cant stand that. Going direct has so many advantages it’s not even fair, the only reason guitarists don’t like it is out of sheer selfishness. I use that word because I cant think of a better word to describe it.
 
VESmedic said:
I don’t know about a “PA style cabinet”, but if you mean running directly to FOH, then yea that’s for sure a thing, and extremely popular and clean. It’s much better (at bigger venues) than having a cab on stage blasting through the FOH killing the sound of the band as a whole, cant stand that. Going direct has so many advantages it’s not even fair, the only reason guitarists don’t like it is out of sheer selfishness. I use that word because I cant think of a better word to describe it.
Click to expand...

I consider FOH as sound reenforcement, where the IR works super well. You can keep the stage volume down and get great sound from the FOH to cover the venue
 
VESmedic said:
100 percent truth here for sure. My two notes torpedo is completely different in response and feel when playing, or when reamping than when using a real cab and mic. Especially in the low end, I can’t get near the low end with Two notes as I can with my cab: the good kind of low end. That harmonicly rich build up that blooms like nothing else: impossible to get in my experience compared to a real cab. I assume it has everything to do with two notes fixed impedence load ( while it is a reactive load, that still doesn’t solve every issue.)
Click to expand...
VES that lack of low end thump was my experience for years as well, until I did some extensive testing on loads, their effect on the output stage of a given amp, and other fun stuff. Short version is reactive loads vary wildly, and do not deliver consistent results across amps - meaning the effective eq curve will change amp to amp given the same RL!

And the long version...ultimately we created our own IR's, ones that compensate for how the amp reacts differently to the specific reactive load that will be used.

For example in a Diezel VH4 - Mesa 4x12 cab combo, the amp puts out noticeably more under 500Hz than when coupled to a Suhr reactive load. It responds differently again with a Tone King Ironman II, and sounds awful with the Two Notes stuff. So it's not necessarily that the IR is lacking lows (it's just a simple eq curve after all), it's the difference in impedance curves between that particular amp-cab to the amp-RL combo contributing to the change in eq.

So we created a separate IR for every amp-cab combo in our collection, rather than just one for every speaker. The IR's are so close now that they almost phase cancel with the original mic'd cab, and all that low end chunk is retained. And it only took a few hundred hours! Hmm, I'm starting to think my obsession with tone is slightly unhealthy.
 
Last edited:
ZEN Amps said:
VES that lack of low end thump was my experience for years as well, until I did some extensive testing on loads, their effect on the output stage of a given amp, and other fun stuff. Short version is reactive loads vary wildly, and do not deliver consistent results across amps - meaning the effective eq curve will change amp to amp given the same RL!

And the long version...ultimately we created our own IR's, ones that compensate for how the amp reacts differently to the specific reactive load that will be used.

For example in a Diezel VH4 - Mesa 4x12 cab combo, the amp puts out noticeably more under 500Hz than when coupled to a Suhr reactive load. It responds differently again with a Tone King Ironman II, and sounds awful with the Two Notes stuff. So it's necessarily that the IR is lacking lows (it's just a simple eq curve after all), it's the difference in impedance curves between that particular amp-cab to the amp-RL combo contributing to the change in eq.

So we created a separate IR for every amp-cab combo in our collection, rather than just one for every speaker. The IR's are so close now that they almost phase cancel with the original mic'd cab, and all that low end chunk is retained. And it only took a few hundred hours! Hmm, I'm starting to think my obsession with tone is slightly unhealthy.
Click to expand...


this is smart! Never thought about doing that. So just so I understand you, you made specific IR’s of THAT specific cab that you own with a neutral power amp? Or did you incorporate the actual amps power amp into the equation? I assume that’s what you meant, because I would guess that would be the only way you could actually get the “true” impedance curve. So then, with that IR you made, you would only use that IR ( or multiple, however many you made with that specific setup) with that specific amp you made the IR with? Is that right? Sounds like a genius idea, and something I would benefit from or others who own multiple heads and multiple cabs to actually use those IR’s made with that specific amp.
 
Actually my enthusiasm for knowledge sharing might be getting me into trouble - this will likely end up in a commercial product at some point. Hit me up via PM mate (y)
 
ZEN Amps said:
Actually my enthusiasm for knowledge sharing might be getting me into trouble - this will likely end up in a commercial product at some point. Hit me up via PM mate (y)
Click to expand...
Or get you rich. That is an incredible idea. I dont really research IRs these days and I know technology has gotten very good but this sounds like something that isnt out there. Might wanna delete these posts if there isnt a patent on this.
 
Deleted member 26052 said:
Or get you rich. That is an incredible idea. I dont really research IRs these days and I know technology has gotten very good but this sounds like something that isnt out there. Might wanna delete these posts if there isnt a patent on this.
Click to expand...

Im not sure yet that this hasn’t been done, if it’s what I’m thinking zen has done. There are many IR’s out there that were done with a specific amp and cab instead of the traditional neutral power amp and cab setup for making IR’s. However at the same time, I’m not sure that this is what zen is referencing exactly, but maybe, we will see .
 
Last edited:
I'm not sure I'm setting the world on fire with new ideas, but it's an approach that works considerably better than using any old IR - and it's consistent.
 
Last edited:
You must log in or register to reply here.
Back
Top