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Are the Helix impulses "actual" impulses?


mitchbakermusic
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So I'm neck deep in making a comparison series between Fractal and the Helix right now, and I've been bothered so much by a thought that I had to come here for a definite confirmation or denial.

 

My question is this: Are the Helix cabinet impulses the actual microphones being placed in front of the cabinet being captured, or are the microphone models actually impulse responses of the microphones being placed upon a neutral reference microphone's impulse response of the speaker cabinet? If that phrasing doesn't make sense, I'll explain with two methods, using an SM57 as an example:

 

Method One: The Standard.

Cabinet is set up, an SM57 microphone is set up in position to capture it, impulse is taken, then the microphone is moved around and captured in various other positions/distances. Then the SM57 is changed for, say, an R121, and the whole cycle repeats itself.

 

Method Two: The Cool, Modern, Easy Way

Cabinet is set up, a neutral reference microphone (designed for completely flat frequency response) is set up in position to capture the cabinet in all the same positions as you would a normal mic. Then a impulse response of an SM57 is placed on top of the neutral impulse response to give it that flavor, and so on and so forth with other microphones' impulse responses.

 

The reason I ask is that it is highly unusual for me to see that the AKG D12 and D112 are options for every single guitar amp, and I feel like that would be way too much effort for Line 6 to go through on microphones that are basically only used for bass amps and kick drums. It makes a lot more sense that they simply had those impulse responses to stack on top of each other, and figured they might as well include them with the guitar cabs.

 

This was something Fractal was doing for quite some time before they started focusing more on actual microphone blends, so this is no accusation of foul play, I would just like a clear answer on this.

 

Thanks!

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Likely option 2 as Two Notes and similar products approach the variables. However, this is only speculation.

 

Option 1 would be available by taking IR's of Kemper cabinets that people have mic'd up....however unless they are merged you don't get complete amp/cab separation and it might be hit and miss.

 

How are the IR providers noting there process? It seems that by the number of files for some it might also likely be software models??

 

 

Recommendation when doing your comparisons after seeing two of the latest. Set up similar cabs so the amp models can be focus of comparison and take some time to setup the amp at least on the basic level. Most everyone will adjust hi and low cut on the cab. By doing this in your videos it will show that you are working toward a true comparison rather than bashing one or the other based on fizz, etc. I would say that your efforts are a little better, but you are active on the Fractal forum so transparency provides a reputable view. Maybe even use similar IR's on like amp presets.....just a recommendation from my perspective.

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I doubt you'll get a definitive answer on this, but I'm not sure why that would matter either way quite frankly.  The two cabinet processes are clearly different, but both serve different purposes, and are useful in different ways.

 

Method One provides a very exact duplication of speaker, mic, and mic placement, but it can't be changed without changing to a completely different IR.  It's also subject to the environment it was recorded in and carries with it those artifacts from that environment.

 

Method Two is probably not as precise in it's duplicaiton but offers the advantage of being able to quickly and easily change microphones, placement and certain room artifacts.

 

For myself I prefer the convenience of Method Two as it allows me to quickly audition various setups to get to the sound I'm looking for.  Some people may prefer to be purists and are willing to pay the penalty in terms of lack of convenience and flexibility.  I'm just glad I have the ability to go either way if I want to.

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How are the IR providers noting there process? It seems that by the number of files for some it might also likely be software models??

 

 

Recommendation when doing your comparisons after seeing two of the latest. Set up similar cabs so the amp models can be focus of comparison and take some time to setup the amp at least on the basic level. Most everyone will adjust hi and low cut on the cab. By doing this in your videos it will show that you are working toward a true comparison rather than bashing one or the other based on fizz, etc. I would say that your efforts are a little better, but you are active on the Fractal forum so transparency provides a reputable view. Maybe even use similar IR's on like amp presets.....just a recommendation from my perspective.

I know there are plenty of other companies that do this, and as I said in the OP, this is no accusation of foul play, I just want to know if this is commonly known information already about the Helix. Fractal provides notation between which impulses were captured with a neutral microphone and which are blends of actual microphones, though that notation is a little confusing and you have to research what the suffixes mean to understand and distinguish them.

 

And in the first part of the series, I was running through the exact same cabinet impulse set up in my DAW, so I'm not exactly sure what you're referring to there. I ignored hi and low cut because as I said in the intro, they weren't intended to be the best tones in the world and you can dial these in to your preference when you actually have the units, but I was trying to just give you a straight up comparison of the amp models alone, not dialing things in to my or your personal preference. Not to mention I wasn't actually using the cabinet blocks built into the units.

 

I'm completely transparent in saying I prefer the Fractal, I think that's perfectly clear, I'm not trying to act like I'm totally unbiased. I said that in the intro to the video. I am more active in their community because I prefer their product an use it more often, simple as that. However, I have no vested interest in the success of Fractal or the failure of Line 6, I'm doing my best to support my pro-Fractal opinions with effective evidence, and I'm giving the Helix credit where I think credit is due. I am not on a crusade to "bash" one or the other, I'm just trying to cut through all the crap that's out there and give people honest information about the differences between the two so people can decide for themselves what's right for them.

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the following article taken from the Helix blog and pasted here could perhaps partially answer to your question...

 

We call the speaker emulations in Helix “hybrid cabsâ€, because they use a number of proprietary algorithms to reproduce the same frequency and dynamic accuracy typically seen in a 2048-point impulse response, but at far lower DSP usage.

 

Not only that, a hybrid cab allows you to move the microphone from directly on the grill to up to 12 inches away (in .5 inch increments), and accurately captures the proximity effect/bass boost of the microphone in all positions while doing so. All of this detail means that the speaker cabinet reacts just like the real thing, not just sounding better but feeling better under your fingers.

 

Yeah this part is making me think these are stacked impulses rather than actual microphones. Perhaps even the proximity/distance parameter is impulse based as well? Maybe we'll never know for sure :(

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I tend to believe the same thing..

IMO the mics are not modeled, and therefore not added to mic-neutral IRs..

 

Might be but the bass mics on the guitar cabs make me lean toward modeled. Same with the 2 Notes and Atomic. It's really speculation as I'm sure no one will confirm since it's part of their proprietary magic sauce.

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So I'm neck deep in making a comparison series between Fractal and the Helix right now, and I've been bothered so much by a thought that I had to come here for a definite confirmation or denial.

 

My question is this: Are the Helix cabinet impulses the actual microphones being placed in front of the cabinet being captured, or are the microphone models actually impulse responses of the microphones being placed upon a neutral reference microphone's impulse response of the speaker cabinet? If that phrasing doesn't make sense, I'll explain with two methods, using an SM57 as an example:

 

Method One: The Standard.

Cabinet is set up, an SM57 microphone is set up in position to capture it, impulse is taken, then the microphone is moved around and captured in various other positions/distances. Then the SM57 is changed for, say, an R121, and the whole cycle repeats itself.

 

Method Two: The Cool, Modern, Easy Way

Cabinet is set up, a neutral reference microphone (designed for completely flat frequency response) is set up in position to capture the cabinet in all the same positions as you would a normal mic. Then a impulse response of an SM57 is placed on top of the neutral impulse response to give it that flavor, and so on and so forth with other microphones' impulse responses.

 

The reason I ask is that it is highly unusual for me to see that the AKG D12 and D112 are options for every single guitar amp, and I feel like that would be way too much effort for Line 6 to go through on microphones that are basically only used for bass amps and kick drums. It makes a lot more sense that they simply had those impulse responses to stack on top of each other, and figured they might as well include them with the guitar cabs.

 

This was something Fractal was doing for quite some time before they started focusing more on actual microphone blends, so this is no accusation of foul play, I would just like a clear answer on this.

 

Thanks!

 

 

 

the following article taken from the Helix blog and pasted here could perhaps partially answer to your question

 

------------------------------------------------------------------------------------------------------------------------------------------

 

Helix Hybrid Cabs

 

...

 

We call the speaker emulations in Helix “hybrid cabsâ€, because they use a number of proprietary algorithms to reproduce the same frequency and dynamic accuracy typically seen in a 2048-point impulse response, but at far lower DSP usage.

 

Not only that, a hybrid cab allows you to move the microphone from directly on the grill to up to 12 inches away (in .5 inch increments), and accurately captures the proximity effect/bass boost of the microphone in all positions while doing so. All of this detail means that the speaker cabinet reacts just like the real thing, not just sounding better but feeling better under your fingers.

...

 

 

I don't presume to know what technology Line6 has implemented in their cabs but from this blurb in their description of how their "hybrid" cabs are designed with "proprietary algorithms" it sounds like perhaps they figured out a way to combine an IR with mic modeling in such a way that rather than having a different "stacked" IR for each mic distance, instead they have a parameter that can be changed in concert with the IR that changes the sound and the perception of the mic distance. In other words, perhaps they just figured out how to make mic distance an adjustable parameter in tandem with a single IR. Almost like they have shoe-horned in their own programming into IRs which would ordinarily be treated as a sort of monolithic .wav file. Or.. perhaps it is just stacked separate "Mic" IRs, or changing the mic distance selects a completely different IR, I am strictly speculating.

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While I think their process is closer to #2, there is a "tell" that it's more than that.   " a hybrid cab allows you to move the microphone from directly on the grill to up to 12 inches away (in .5 inch increments),"   Specifically the .5 inch increments and the limit of 12" and the unwritten lack of offset/angle.   That functionality of .5" increments rather than just whatever distance you want (which is a model elsewhere throughout the helix) indicated they sampled  impulses at .5" increments.  Now, digitally, they may only be changing the applicable portion of the response that changes at difference distances and making enhancements digitally to make it as "real" as possible, but this would account for the increments, and also account for the lack of angle parameter.  The limit of 12" again... if it was completely a model, why would that matter?  

This method, and again it's just a guess, would also make having microphone angles quite a tall order.  Instead of the 24 readings per mic they may have now, add another 10 (0 - 45 degrees at 5 degree increments) at each increment... (10 x 24) and we're up to 240 measurements per mic plus all the overhead to "clean it up/enhance" it in the code. 

 

I'm guessing it's WAY more complicated than this, but just based on other consistencies throughout the Helix, I'd guess they did at least 24 impulse responses per microphone ON EACH CABINET and manipulate what they need digitally to keep size down and to enhance quality.

 

Just a guess.

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When I make a hotdog, do I use real mustard or fake mustard?

 

The only real difference and determining factor is,  how each one tastes to you.

Beginning with a great HotDog, Mustard can improve it! The wrong Mustard can ruin it. But no amount of Mustard can fix a lousy Hot Dog! ;)
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Beginning with a great HotDog, Mustard can improve it! The wrong Mustard can ruin it. But no amount of Mustard can fix a lousy Hot Dog! ;)

Ahh yes, but its only yours and my in·ter·pre·ta·tion on on what is the right or "wrong" mustard... 

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Seems like just a load of EQ matrix filters. I would be satisfied with an amp without a cab but the Helix does not do that. I was integrating my GSP1101 as there are some clean tube models on there I just love. Loop out to the GSP 1101 grab the clean tube amp model w NO cab set on "direct", sounds amazing coming back through the Helix in front of the Helix main amp model. Ever try to use a Helix amp without a cab or how thin the preamp models are? 

Why is there no "direct" option on the Helix instead of all this fuss about IRs and mics. They all change the sound drastically, I just do not get why we have to do this using the IR or whatever the Helix has.

When I play an amp through my std guitar cab they all sound great and you EQ the particular amp to taste. My speakers do not color the hell out of the sound and there is no mic to completely alter the entire thing. I do not like the sound of cheap green low wattage speakers or the sound of hollow box cabs with no sense of dampening of standing waves. So why would I want an IR of such a cab?

I have used speaker line taps like the Radial JBX instead of trying to mic amps to send to the PA or DAW. The Helix has great XLR but there is all that coloring matrix going on. Sorry but the whole IR "shmow" seems to be the wet dream of recording hobbyist who want the sounds of old cabs and low efficient speakers using all sorts of mics that completely change the entire sound. What difference does it make about the amp if it can be completely rendered a crap fest by merely using a IR/hybrid and a weird mic? I thought all this modeling was trying to attain the feel, sound and response of a real amp. As long as you have a great IR apparently it does not matter a rat's a s s about the amp model. 

Seems just all EQ and filtering to me. Someone asked if all the Helix cab things are not just the same filter block tweaking EQ with added mic filter blocks to change the tones thinking you are dealing with different cab IRs. To me the musical question of the day is: are recording hobbyists sending us down the wrong road focused on recording rather than if a modeler can replace a real amp playing live??? 

It seems very easy to get caught up in the virtual illusion of the Helix world, one I am using this amp wit this cab and this wonderful mic, no you really are not. 

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Seems like just a load of EQ matrix filters. I would be satisfied with an amp without a cab but the Helix does not do that. I was integrating my GSP1101 as there are some clean tube models on there I just love. Loop out to the GSP 1101 grab the clean tube amp model w NO cab set on "direct", sounds amazing coming back through the Helix in front of the Helix main amp model. Ever try to use a Helix amp without a cab or how thin the preamp models are? 

Why is there no "direct" option on the Helix instead of all this fuss about IRs and mics. They all change the sound drastically, I just do not get why we have to do this using the IR or whatever the Helix has.

When I play an amp through my std guitar cab they all sound great and you EQ the particular amp to taste. My speakers do not color the hell out of the sound and there is no mic to completely alter the entire thing. I do not like the sound of cheap green low wattage speakers or the sound of hollow box cabs with no sense of dampening of standing waves. So why would I want an IR of such a cab?

I have used speaker line taps like the Radial JBX instead of trying to mic amps to send to the PA or DAW. The Helix has great XLR but there is all that coloring matrix going on. Sorry but the whole IR "shmow" seems to be the wet dream of recording hobbyist who want the sounds of old cabs and low efficient speakers using all sorts of mics that completely change the entire sound. What difference does it make about the amp if it can be completely rendered a crap fest by merely using a IR/hybrid and a weird mic? I thought all this modeling was trying to attain the feel, sound and response of a real amp. As long as you have a great IR apparently it does not matter a rat's a s s about the amp model. 

Seems just all EQ and filtering to me. Someone asked if all the Helix cab things are not just the same filter block tweaking EQ with added mic filter blocks to change the tones thinking you are dealing with different cab IRs. To me the musical question of the day is: are recording hobbyists sending us down the wrong road focused on recording rather than if a modeler can replace a real amp playing live??? 

It seems very easy to get caught up in the virtual illusion of the Helix world, one I am using this amp wit this cab and this wonderful mic, no you really are not.

There's a lot that you say in the above, but I think it boils down to, at least my interpretation of what you're saying, is that you don't like the idea of modeling the mic/cabinet combination vs not.

 

Helix and is capable of bypassing that part of the modeling. I understand you have some really nice cabinets and speaker combinations that you like a lot.

 

Have you tried building patches that do not model the mic/cabinet or use IRs, and instead send the raw modeled amp signal out the Helix outputs, and feed those into a good quality power amp and then direct to your real, favorite, high quality cabinet(s)?

 

I'd be interested if that gave you more what you're looking for, and seems like that might be the "direct" option that you mention above that the Helix does not do (I think it does), unless I'm misinterpreting your statement (really a question): "Why is there no "direct" option on the Helix instead of all this fuss about IRs and mics.[?]" I think the answer is that there is.

 

As far as IRs, Helix cabs, etc, the process is a pretty sophisticated transformation of the signal. Same type of modeling/filtering that happens for high quality reverbs to capture the reverberation characteristics of real spaces from cathedrals to caves to tiled bathrooms.

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Seems like just a load of EQ matrix filters. I would be satisfied with an amp without a cab but the Helix does not do that. I was integrating my GSP1101 as there are some clean tube models on there I just love. Loop out to the GSP 1101 grab the clean tube amp model w NO cab set on "direct", sounds amazing coming back through the Helix in front of the Helix main amp model. Ever try to use a Helix amp without a cab or how thin the preamp models are? 

Why is there no "direct" option on the Helix instead of all this fuss about IRs and mics. They all change the sound drastically, I just do not get why we have to do this using the IR or whatever the Helix has.

When I play an amp through my std guitar cab they all sound great and you EQ the particular amp to taste. My speakers do not color the hell out of the sound and there is no mic to completely alter the entire thing. I do not like the sound of cheap green low wattage speakers or the sound of hollow box cabs with no sense of dampening of standing waves. So why would I want an IR of such a cab?

I have used speaker line taps like the Radial JBX instead of trying to mic amps to send to the PA or DAW. The Helix has great XLR but there is all that coloring matrix going on. Sorry but the whole IR "shmow" seems to be the wet dream of recording hobbyist who want the sounds of old cabs and low efficient speakers using all sorts of mics that completely change the entire sound. What difference does it make about the amp if it can be completely rendered a crap fest by merely using a IR/hybrid and a weird mic? I thought all this modeling was trying to attain the feel, sound and response of a real amp. As long as you have a great IR apparently it does not matter a rat's a s s about the amp model. 

Seems just all EQ and filtering to me. Someone asked if all the Helix cab things are not just the same filter block tweaking EQ with added mic filter blocks to change the tones thinking you are dealing with different cab IRs. To me the musical question of the day is: are recording hobbyists sending us down the wrong road focused on recording rather than if a modeler can replace a real amp playing live??? 

It seems very easy to get caught up in the virtual illusion of the Helix world, one I am using this amp wit this cab and this wonderful mic, no you really are not. 

 

I'm confused. If you don't like the cabs, why are you using them? I don't use the amps or cabs and just go into the front of an amp.

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When I make a hotdog, do I use real mustard or fake mustard?

 

The only real difference and determining factor is,  how each one tastes to you.

Of course if it sounds good to you, it doesn't matter. I was just curious if there was clear knowledge one way or the other among the Helix community, and it appears that there isn't. Again, no cry of foul play if Line 6 does this.

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  • 1 month later...

I'm confused. If you don't like the cabs, why are you using them? I don't use the amps or cabs and just go into the front of an amp.

I gave up using traditional guitar amps a long time ago. The Helix is my latest working of a non guitar amp rig. If you are using the Helix to run into an amp and not using the modeling, you wasted a whole lot of money. I do like a few cabs using the Coles 4038 what I was hating as that 57 and similar mics even on various IRs that sound is so thin and midrangy. I finally got some Ribbon mic IRs I like and stopped using the internal cabs. Some of the 4x12s with the 4038 sounded pretty good to me providing one does not choke off the frequency response like many seem to do. I am not interested in a thin midrange guitar sound and that seems to be a raving fav among many. What I was trying to get at in the former post was how much mics alter the sound and why can't there be some sort of DI like thing which gets the amp sound without coloring it so much with speaker and mic IRs. A bad speaker sim or IR can ruin an amp tone real quick or make it exceedingly difficult to get the tone one is after as is it the amp or the IR? Can a great IR make a crappy amp model sound good, maybe. Impulse Response seems to be the name of the game. 

I guess the point is you cannot use an amp without an IR whereas on your normal rig using your speakers natural sound you do not need a coloring IR and mic thing. 

I use a blend combination of a high end guitar speaker loaded 4x12 and a FRFR rig. 

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If you are using the Helix to run into an amp and not using the modeling, you wasted a whole lot of money.

What? Some peoples pedalboard cost more than Helix, and when you think about the routing, 8x8 interface, being able to monitor yourself with an amp and going to FOH with modeling enabled, how can one say that it's a waste of money? I don't use an amp with Helix, but Helix is designed to be flexible enough to use in all kinds of situations. That's why they also gave us 4 loops ;)

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What? Some peoples pedalboard cost more than Helix, and when you think about the routing, 8x8 interface, being able to monitor yourself with an amp and going to FOH with modeling enabled, how can one say that it's a waste of money? I don't use an amp with Helix, but Helix is designed to be flexible enough to use in all kinds of situations. That's why they also gave us 4 loops ;)

 

Yeah, actually, I think even if the Helix didn't offer amp/cab modeling, it would be a good bargain as a multi-fx processor alone. I love using it with real amps for effects only. It works great. I mean if you think about what you get - the 4 loops, the scribble strips, snapshots, MIDI control, and then all the effects. You couldn't really build a pedalboard with all those features for less than $1500.

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You're new here, aren't you? ;)

 

You'll have better luck asking for pictures from the CEO's most recent colonoscopy...

Now why would they give away their prized profile shot? ;) Seriously I don't understand this mindset. If (assuming Im correct) the IR's used by Helix are proprietary to Helix only, then why not release the software and let us make our own? This abundance of IR's would only sell more Helix units wouldn't it? Im only going by the fact that so far, the idea of making amps n cabs and such worked pretty good for Kemper. Granted theres some that just don't want to weed thru the junk to find a diamond tone wise.

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What? Some peoples pedalboard cost more than Helix, and when you think about the routing, 8x8 interface, being able to monitor yourself with an amp and going to FOH with modeling enabled, how can one say that it's a waste of money? I don't use an amp with Helix, but Helix is designed to be flexible enough to use in all kinds of situations. That's why they also gave us 4 loops ;)

Yup, mines is a glorified G-System replacement that I also use as a direct recording rig

 

Edit: I actually use the soldano clean channel in conjunction with my amps dirty channel because a) it sounds great and b) saves me having to get a cable cut to work with my amps 6 pin din

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Of course if it sounds good to you, it doesn't matter. I was just curious if there was clear knowledge one way or the other among the Helix community, and it appears that there isn't. Again, no cry of foul play if Line 6 does this.

Hey Mitch, I get your wavelength on this. It's interesting from a technological standpoint - "better" or "worse" is irrelevant. I'm down with that outlook.

 

To directly answer the original question, nobody here knows exactly how they are creating the cab emulations.

 

Your theory of stacked impulses is sound to me and I agree that is one possible method that could deliver what Helix is doing but I'm not convinced that is what we are looking at here. I'll try to meander through why I think that...

 

*begin speculation*

 

From what I understand about the way the HX modelling system works, they are using a profiling system similar to that of the Kemper at a component level to create or "capture" algorithms that represent each section of the circuit in, for example, an amplifier in order that the final emulation of the complete device has the same interactivity between its controls and reactivity and dynamic quality in the complete emulation as in the original device.

Now, given that this is their supposed approach to circuits it stands to reason that they would be applying a similar approach to cab and mic sims in order to maintain a uniformity within their platform for the actual processing (less different means less difficult when it comes to programming code and hardware). If that is the case then my understanding is that to actually stack impulses would require a much greater processing overhead than the Helix hardware allows for (given that you can only load a couple of IR before it poos the bed) leading me to think this cannot be the method they are employing and it would be more logical for them to take a similar approach to how they are supposedly creating the amplifier or effects emulations.

My idea of it is that rather than stacking impulses what they are doing is that they are instead combining a bunch of distinct algorithms for each option within a cab block and "generating" a single impulse based on the selected options entirely separate from the audio path and then conforming the signal to that single generated IR. I think this because this method minimises the DSP heavy process of conforming a signal to an IR to just a single instance while still providing all the options for variability we seem to have in the box with comparatively little processing overhead. The group of algorithms generates the IR once upon configuration and then the only realtime process that needs carried out is conforming the signal to that single IR.

 

*end speculation*

 

What think you?

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