IR Properties

Discussion in 'Digital & Modeling Gear' started by Jay Mitchell, May 17, 2019.

  1. vtgearhead

    vtgearhead Silver Supporting Member

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    Home-made EMT plate? Cool!
     
  2. big mike

    big mike Plexi Loving Admin Staff Member

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    Quit the bickering.
    Threads been reviewed by multiple moderators and no spam has been seen by our eyes.

    And I’m as anti this section as it comes

    Stop thread crapping or we will ban from the thread
     
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  3. Chocol8

    Chocol8 Member

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    So I got a little headphone time again tonight. Still waiting on an opportunity to play LOUD.

    Tonight I created a couple of new patches in the Amplifire using their D lux amp model with all default settings (I think everything at 5 or 12:00) and the cab block starting at the default settings. No other blocks were used.

    Jay M B was horrible and was tossed very quickly. I mostly compared A and C to each other and to Atomic’s included D Lux cab. I used a strat with SD Antiquity Surfer II’s straight, with a Clapton active midboost (midboost O but volume 10 which is hotter than unity gain) and with a Tumnus (Klone) set to a slight clean boost. All combinations, mostly on the neck pickup tonight.

    The Atomic cab is bass and mid bass heavy. VERY heavy. Not wanting to get too involved, I tried to tame it with just the “bottom” knob in the cab block. Even with that control at -12 dB it was still too boomy but getting into the ball park of A.

    Jay M A was also bass/mid bass heavy but not as much as the factory cab even with the -12 dB bottom setting. Reducing the “bottom” by 6 dB helped get this one closer to JM C but it was still thicker. The first take away is that you can’t fix the extra bass with a simple knob turn on the Amplifire. It’s going to take more effort and one or more EQ blocks at a minimum. I was hoping the cab block controls would get you closer than they did but that was wishful thinking and I knew better.

    JM C was my favorite in this application. At first I thought I was getting more breakup with this IR than the others when pushing it with a hotter signal which didn’t seem to make sense. Then I realized the amp block was distorting the exact same (duh!) but the other IRs were obscuring it a bit. Jay M C was not boomy and was the most clear and detailed sounding. Even with the “Bottom” dialed back on A, C was clearer.
     
  4. Dave Merrill

    Dave Merrill Supporting Member

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    I hope that as the preeminent (only?) expert in the field, you'll find a way to get a collection of these out to the public, through your own company, or by partnering with someone else.
     
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  5. Corinthian

    Corinthian Member

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    I’ve just tried Jay’s IRs and I’m coming at this from a slightly different angle to most. I’ve spent a lot of time in studios and I’m comfortable with the sound of my guitar through monitors. I have never been looking for the ‘amp in the room’ thing from a modeller.

    First of all B… yeah, that’s horrible. Sound like it was captured in a bathtub. Even with judicious low cut it’s not something I’d ever use on its own. I don't think using this is a fair comparison as it sound much worse than any commercially available IR I've heard.

    Agree with others that C sounds like the far-field impulse to me and I'm going to go with that assumption… so the following is moot if that’s incorrect.

    Given I’m looking more for good recorded tones rather than AITR, and that the vast majority of recordings have been done with close mics I was expecting to say that the far-field sounded more like an amp in front of me but that I’d prefer to use the close-mic response for my purposes. But the far-field doesn’t just sound more like it’s in front of me. It’s clearer, more balanced and just sounds better. Even after applying a low cut and other EQ to the close-mic I greatly prefer the far-field.

    But sure, on it’s own you’d probably expect the far-field to sound better, but what about in the context of a mix? Pretty much all the greatest recordings were close-miced. Well in a mix the clarity of the far-field is still there, making it more clearly audible. But more importantly for me, it obscures other instruments far less. So not only can I hear the guitar better, I can hear everything else better too. BTW, that can’t completely be explained by the proximity effect of the close-mic creating more bass, because it’s still the case after low cutting the close-mic. It is of course just one example in one song but if all far-field IRs are like this then they will make the sound engineer’s job much easier!

    I’m not going to write-off close-mic IRs just yet as they have worked well for me and many others. I’d also like to try out some different cabinets suited to different kinds of music so I can hear the differences in some other contexts. But based on this experiment (and the assumption that C is the far-field) I’m a believer.
     
  6. Mark Al

    Mark Al Member

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    Exactly my experience as well, Jay's FF IR works really well when played in a mix. It's fundamentally different tonal characteristics than near field IRs.

    I have since tried to EQ a couple of my patches with either Helix stock cab or other NF IRs, with Jay's FF IR as the benchmark. I tries to dial the NF IRs to sounds as close as possible to it in term of its tonal balance and warmth... Well, for certain NF IRs, after some work, a lot of high/low cuts, it can be tweaked somewhat similar, however the typical NF IR always have some offending frequencies where it's either humped or valley-ed, which becomes painfully obvious when compared with to a balanced benchmark. And I feel reluctant to use Parametric EQ to tweak further... At the same time, Jay's IR works out of box effortlessly with no tweaking necessary.

    From my perspective, this is qualified as a game changer.
     
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  7. BjarneDa

    BjarneDa Member

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    Yes but also every great recording of guitar/s is heavily filtered in the mix to make sure it didnt fight with any other instrument just listen to many of the available isolated guitar track you find on internet and i.m.o all of them sounds crap on its own.
     
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  8. Corinthian

    Corinthian Member

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    Oh, I'm well aware of that. But the point is very few of them were far-field miced so if we're after great recorded guitar tones it would be a fair assumption that a close-miced IR would get you there. In this case the IR that sounded best on its own also sounded best in the mix.
     
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  9. nicolasrivera

    nicolasrivera Gold Supporting Member

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    Altiverb delivers the best results. IMO
     
  10. Jay Mitchell

    Jay Mitchell Member

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    Thanks for the confirmation. I've been saying exactly the same thing now for more than 11 years.
     
  11. Jay Mitchell

    Jay Mitchell Member

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    Let me offer one note of clarification: per post #40, the chart at the bottom (Log IR^2 of the NF IR) clearly shows a reflection at ca. 8ms. So this is not reflection free. Because I elevated the cab about 4 feet off the floor, the floor reflection was shifted back in time and reduced in level by 12dB compared to what you'd get with the same cab on the floor. Its effect has been mitigated but not eliminated altogether. I can acquire reflection-free near field IRs, but it's a much bigger hassle, and I have no personal interest in doing so.
     
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  12. Jay Mitchell

    Jay Mitchell Member

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    Just to clarify: it is a commercially available IR. That's why I included it. If you'd auditioned that and thought that far field IRs sounded like that, you'd have gotten entirely the wrong impression.
     
    Last edited: May 24, 2019
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  13. gigsup

    gigsup Supporting Member

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    I wouldn't come to this conclusion.

    It's interesting that many have pointed out that the majority of electric guitar recordings have been done with close mic'ing, but that 'you never listen to the amp that way'.
    But if you think about it, you do in fact listen to the amp that way.
    You listen to those recordings or performances through other playback systems, on studio monitors, headphones, or PA systems which are doing their best to reproduce 'that sound' of that instrument in that room at that distance.
    Getting that part of it right is just as challenging for musicians as engineers, given different venues, different equipment, so many variables.

    What is being presented here, as I understand the thread, is a method to obtain Impulse Responses in such a way that only the direct sound from the speaker under test is obtained within the critical 20ms of the sample. Knowing that sound moves at roughly 1 foot per millisecond, this implies that the distance from the speaker to any reflective surface (assuming you are in a room) is no less than 10 feet from the speaker
    in any direction. This implies the test microphone is equally distant from any reflective surface, to insure first reflections are beyond 20ms as well.
    It should be noted that the mic is as much a part of the system as the speaker itself.
    You can move the mic towards the speaker and take an IR, without paying the room reflection tax, but things change acoustically the closer you move the mic to the speaker.

    I'm here to observe and hopefully learn some new things.
    If this IR method whittles down the sound of my favorite amps to 10-20 IR's each, and they are consistent between many playback systems, that's fantastic.
     
  14. ColdFrixion

    ColdFrixion Member

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    While it's true there are many examples of guitars that have been EQ'd to fit the mix and sound different in isolation, it's simply not true that every great recording featuring guitars are heavily filtered and sound like crap on their own. Three well-known examples include Journey's "Don't Stop Believin'", Heart's "Barracuda" and .38 Special's "Caught Up In You". The guitars for each sound good, if not great, in isolation and have not been heavily EQ'd to fit the mix compared to how they sound during isolated passages.
     
    Last edited: May 24, 2019
  15. Corinthian

    Corinthian Member

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    While respecting the non-commercial rules here, the obvious next question is how to I (as someone who doesn't capture his own IRs) start to acquire far-field IRs? AFAIK nobody is offering them commercially using your techniques, is that correct?


    Well I guess someone somewhere must have found some value in it then! For my own comparisons I loaded up one of the stock 1X12 Deluxe IRs in the Axe-FX III and it sounded much closer to either of the other two IRs. Between the stock IR and your A, I could go either way depending on the tone I was after. C was the clear leader though.


    I'm not sure I follow. What conclusion would you not come to?

    Again I'm not sure I'm following so excuse me if I'm talking at cross purposes. But there really is a big difference between how you hear a close-miced amp compared with hearing one in the room with you. As you say in your next paragraph this is about capturing the sound of the cabinet without the effects of the room, which is one of the things sound engineers are trying to achieve with close-micing. Because a guitar part is more than 20ms long you have to do that with isolation (which is less than perfect) and keeping the mic close to the speaker, but with a short enough IR and a large enough room it's possible to move the mic far enough away to capture the entire cabinet without the effects of the room. I think that's what you're saying too but I don't follow the part above.
     
  16. gigsup

    gigsup Supporting Member

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    The conclusion I don't arrive at is that IR's will make a sound engineers job easier to do.
    If you are working with a sound engineer, you're not paying that person to stand in the room with you and admire your amp sounds, though they should be paying close attention to them.
    They are employed to balance the sounds between all inputs into an aesthetically appealing whole, while maintaining that sound in context with the mix through a wholly different playback system in another acoustic space, be it in the control room, a church service, or dozens of wireless headphones.
    But how they accomplish that is not the point.
    The point is that sound, however it is generated, is mixed and presented on a totally different playback system, to the satisfaction of an audience.

    So, as a real life application in live sound, you have a synth that perfectly samples a Steinway piano, or a genuine Steinway piano.
    Someone makes the choice to use one or the other, despite your personal preferences as a sound engineer.
    The same choices follow with a mic'd cab or an IR emulation of the cab.
    Not saying one is better or worse, I am saying you will always hear the results through a different speaker system, with its own limitations enforced on it by the acoustics of the space it is in.
    Particularly with regard to live sound, that is the gig.

    I was referring to the conditions that (I assume) are necessary to record your own reflection free IR, not the actual recording of a guitar part. See below. (You can guess how big the warehouse is)

     
  17. antcarrier

    antcarrier Member

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    This is... too true. I have had quite a few 'bad batches' even when I thought I had everything set up correctly.
    Especially being an amateur recordist myself, capturing FF IRs is hard and requires a lot of patience. The results are rewarding, however.
     
    Last edited: May 24, 2019
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  18. Yek

    Yek Member

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    Like an airplane crashing through the roof? :D
     
    Last edited: May 24, 2019
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  19. yeky83

    yeky83 Member

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    I think it's more likely that a sound that does not contain significant early reflections will be easier to be "mixed and presented on a totally different playback system, to the satisfaction of an audience." And it certainly helps that the sound signature does not change drastically with every tiny mic movement, or that you have to deal with hundreds of IRs per cab.
    Particularly with regard to live sound, if the band sounds good together as an ensemble, then the use of a matching far-field IR within the context of that band will likely sound good.
     
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  20. Corinthian

    Corinthian Member

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    I think maybe you interpreted my saying the engineer’s job would be much easier as meaning it would become obsolete, or so easy that anyone could do it. I certainly don’t mean it’ll become that easy.

    What I mean is that this one particular IR in the one particular context I tried it was both more audible and obscured other instruments less than the two close-miced IRs I tested it against. I’d love to test more but if that is the case with other far-fields in other mixes (and it may not be) then a major part of mixing, that is creating space so everything is audible, will be much easier than it is with current IRs.
     

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