IR Properties

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

  1. yeky83

    yeky83 Member

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    This probably helps:
    https://www.thegearpage.net/board/index.php?posts/28560725/
    "cancellation of low frequencies that acoustic dipoles naturally produce..."

    And I gathered some of his quotes from other threads here:
    https://www.thegearpage.net/board/index.php?posts/28586023/
     
  2. gigsup

    gigsup Supporting Member

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    Hey, look!!

    A trail of breadcrumbs that leads into the forest...
     
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  3. DreamTheaterRules

    DreamTheaterRules Former Lyricist for Calhoun Tubbs Silver Supporting Member

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    Todays bread crumbs are the croutons of tomorrow...
     
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  4. Jay Mitchell

    Jay Mitchell Member

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    Try not to get distracted by the trees....
     
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  5. DreamTheaterRules

    DreamTheaterRules Former Lyricist for Calhoun Tubbs Silver Supporting Member

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    While also trying not to take a header on one of them... as several have done in this thread. :)
     
  6. Guitardave

    Guitardave Supporting Member

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    Finally got around to trying the IRs Jay sent. My apologies for the long delay.

    Short version is I found it much like the consensus opinions.

    IR A - good but I'd need to do some adjustments to make it work
    IR B - bad (really bad)
    IR C - nicely balanced and my favorite of the three

    Whether I prefer that IR to anything else wasn't really the point of the thread as far as I can tell? And I haven't had a chance to play them thru and speakers yet, only headphones. Each playback is different any way..

    And since my recording computer is working again I did a totally non-scientific series of short clips using my go to modeling patch of the Helix Deluxe Normal model. All three of Jay's IRs along with two LRS and two Helix stock cabs. No tweaking amp tone stacks between the options - just choose the normal sort of Deluxe settings I use with real amps (Bass - 4, mids - 5, treble - 4). The IRs have no hi/lo cuts, etc. The Helix cabs are whatever the default settings are when you pull them up. Again - I wasn't really trying to optimize anything in particular - more just curious how much impact the different IR/cab makes. No surprise at all that it's significant!!

    And this test reminded me of how bored I get with all this tweaking stuff. I could easily use several of these with minimal fine tuning.

    I know everyone approaches things their own way. For me tone mostly matters in the moment I'm playing. Does it inspire me to play my best? And the next gig I will dial the gear in differently - but that usually takes me a few seconds.

    Here's the link to the various IR clips if you want to see if you can guess which is which.

     
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  7. gigsup

    gigsup Supporting Member

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    I listened to your samples @Guitardave.
    #7 sounds like the one you were having the most fun with, so that's the one I like the most.

    I know you said it's not scientific, BUT, if I had to decide on the objective differences and attributes between the 7 choices, there are things I'd want to eliminate to reduce my own subjectivity.
    • The guitar would be recorded on a loop, the exact same licks/chords/progressions being used on each clip.
    • All EQ's disengaged. As flat as possible. I think this is important, as I only want to hear the filter effect of the IR, not the modeler.
    • No modulation or reverb effects, dry only.
    • No distortion. Only the clean, undistorted guitar signal through the most neutral digital chain possible, highlighting the IR.

    Someone is going to provide a data set from a 4x12 cabinet, and we all get to use REW to test @yeky83 's conjecture?
     
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  8. Jay Mitchell

    Jay Mitchell Member

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    Consider that, when you listen to a source of sound, you will never hear its average response. The proposed exercise would consume quite a bit of bandwidth and wouldn't demonstrate much of relevance to this thread, although, like any process that generates IRs, it might produce results that some folks would like.

    The only objective I have in acquiring cab IRs is to get a match to the sound and feel of a cab. The only validation for achieving that goal is playing through the IR and comparing it to the cab. Any ideas about postprocessing IRs - including averaging - must pass that test in order for me to consider them useful.

    It only takes a little imagination to realize that postprocessing possibilities offer a huge rabbit hole in addition to the ones that already exist. I did not set out here to share every detail of my acquisition and selection procedure, only to provide a set of minimum criteria and tools with which to evaluate IRs with respect to those criteria. I also shared two IRs that are final results of my procedure. What I have shared here is easily sufficient for anyone who is motivated to begin the learning process for acquiring cab IRs, but I have intentionally left some blanks that will need to be filled in.
     
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  9. Jay Mitchell

    Jay Mitchell Member

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    Seconded. I won't try to discriminate among signal chain differences unless extraneous variables are eliminated.
     
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  10. gigsup

    gigsup Supporting Member

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    Is this lesson done, or are those blanks a different thread?

    I'm confused as to the direction this thread will go in.
     
  11. Jay Mitchell

    Jay Mitchell Member

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    The lesson was entirely contained in posts prior to and including #40. I added some peripheral information after that, but the essentials had already been provided.
     
  12. bbgie1223

    bbgie1223 Supporting Member

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    Just tried these IR's out today. Right up front I'll just say that I'm not very articulate with TGP lingo as it relates to tone. I just know what sounds right to me. First, I didnt care for A. There's no application where this would work for me. Then I tried B. When I did I could swear that it almost sounded like an IR shot of the rear of a 4x12. Dunno that's just what I got. C was certainly the best of the bunch. Very present. Sounds like it will cut through the mix very well. Good sounding IR. Then I got an idea.
    I'm using these with my Gigboard so I can run parallel IR's in the chain. So I put B and C in parallel. Whoa what a sound! Just fantastic. Has all of the thump I need while not getting too wooly. The good thing about doing it this way is that you can perfectly mix the desired levels of each IR. I'm primarily a mid to heavier gain player so really didnt get a chance to try it on clean sounds. Made the Soldano sound as good as I've ever heard one from a digital unit. I know this was probably not the intended use but that's how I'll use it. Thank you Jay!
     
  13. Toffo

    Toffo Member

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    This is interesting, what we’re you using for amplification?
     
  14. Jay Mitchell

    Jay Mitchell Member

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    You're the only person who's reported finding any use for B. FYI, as I pointed out much earlier, that is not my IR. It is a commercially available "far field" IR that is loaded with reflections. It was included for comparison with a reflection-free IR. A and C are IRs of the exact same speaker.
     
  15. the swede

    the swede Member

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    Try A and C together, i did, sounds great.
     
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  16. bbgie1223

    bbgie1223 Supporting Member

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    QSC K8.2
     
  17. bbgie1223

    bbgie1223 Supporting Member

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    I didnt do that but certainly will try it.
     
  18. bbgie1223

    bbgie1223 Supporting Member

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    I should also point out that B is a good bit lower in the mix. Just used as a flavoring for A so to speak.
     
  19. mparada

    mparada Member

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    Finally got around to test those IRs. Thanks @Jay Mitchell!

    tl;dr: Reflections are a hollow nasal low frequencies. C sounds without those reflections, A has some, B has a ton. Helix stock cabs can get close.

    tl;dr2: I'm a noob. Disregard all the rest!

    FYI I'm total noob guitarist with not an ounce of experience so just take this with a heap of salt. :brick

    First the setup: humbuckers > helix (firmware 2.80) > AKG K52 (I also tried with crapy computer monitors and I could hear differences better with the headphones). I used the US Deluxe Nrm model in helix with default knob positions (not my favorite, but easier for other people to replicate).

    If I'm hearing correctly, reflections sound like a hollow nasal cave-like sound in the low end which muddies the notes (can someone confirm that?). B has a ton of reflections (sounds like it was recorded with an amp inside a well...), A has some reflections and C has none. Differences in A and C could also be proximity effects (added bass). And since B is a total different cab the differences in sound could come from everywhere...

    Regarding preference, I think I'd rather use C which has a cleaner, more defined, tone.

    I also tried helix's default cab for this amp model: the 1x12 US Deluxe. It defaults with a 160 Ribbon mic and 80 - 8k low - high cuts. At first, it sounded great! Close to the C IR. Once I removed the cuts it went downhill! Specially the low cut at 80 Hz takes away a lot of this muddied sound (due to reflections? I think so). What I tried was using a 4038 Ribbon at 12" back. It sounded much closer to IR C (and also better) to my ears. That without any low - high cuts. Still, IR C sounded more balanced and defined.

    Side note: compared to the golden years of some of you I have pig iron ears :puh... so what to me "sounded close" may well be night-and-day for you. :dunno

    Am I listening correctly? I mean, are the sound of reflections really this hollow nasal low end? I thought to make it crystal clear one could use a reflection free IR and than add the reflections (through software). Like, if reflections cause a comb filter in particular frequencies, one could simply add a synthetic filter that resembles reflections so that the one and only difference is the reflections. I know Jay mentioned that IR A was spectrally matched to C for comparison, is that the same thing? How far can two IRs be spectrally matched without actually turning one into the other?

    Can't wait to try the 4x12 too!
     
  20. Lele

    Lele Member

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    I love the far field IRs from @Jay Mitchell and I'm very grateful for them.
    I admit that the "C" IR is by far my favorite, and on the contrary I have some work to do to understand if I like the 4x12, too. It's clear that IR will need some deep tweaking of my Helix amp sims (I'd say mainly mid gain tones).

    One observation: the 1x12 "C" IR is really forceful in its "eq shaping", comparing it with my previous experiences with commercial IRs and my own one.
    (English isn't my mothertongue, and I could miss a better term and explanation now on)
    I mean that this IR characterizes the sound a lot, and somehow it makes more uniform and consistent the sound of any amp sim that I pick. But to avoid any misunderstanding I don't mean this in a negative way. On the contrary, I love the clarity I get from it (I think it's really the main thing I noted against any other IR) and the fact that I can use the lows/mids/treble adjustments of the amp sims in their wide range without getting really bad tones.
    I suppose I can say that it's also the typical trait of any real guitar speaker/cabinet to characterize the amp tone a lot, so at the end this IR is just doing its proper work!

    And now I have a one-million dollar question.
    When I use my backup modeler (the cheap and small Zoom G3n) what is the best way to get close(r) to the same (excellent) tone I can get from Helix + Jay Mitchell "C" IR?
    Obviously I have to try and to compare the two units together and not with headphones.
    But after comparing for example in a DAW what the main eq differences are between the Helix and the Zoom G3n, what is the best approach to tweak the tone? Looking at the (differences in) eq peaks or notches (and how wide should they be to have an important impact on the tone?) or else?
    My target is to add a graphic eq + a single band parametric eq in the Zoom G3n fx chain and use them to modify the tone of the speaker sims on board.
     
    Last edited: Aug 1, 2019

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