IR Properties

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

  1. AlbertA

    AlbertA Member

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    It depends on your goal. If your goal is to accurately reproduce the sound of a cab captured by a reflection-free far-field IR, then you need a playback system of sufficient fidelity to do so.

    Jay may be alluding (but I don't want to put words in his mouth) to the fact that in the past people having tweaked an amp model while using a close mic'ed IR, then switching to using the far-field IR and expecting magic to happen without changing any amp settings. Instead, the user should just tweak from scratch just as if you were using the real amp.
     
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  2. Chocol8

    Chocol8 Member

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    The 70 meters was to get 35 meters from any wall so 200 ms travel time. Would 20 ms be enough?
     
  3. dlc86

    dlc86 Member

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    Just tried the IRs Jay sent me today.
    Even though it's not specified which one is the far-field IR, it's pretty easy to tell once they're auditioned, it's one of the most natural sounding IRs I've tried to date (and I've heard literally thousands of them), it has no phasiness at all and I don't need to push the mids on the EQ as I usually do to balance close-mic IRs.
    The close-mic IR sounds good too but has a bit of phasiness and the highs are not as smooth as on the far-field one.
    The "fake" far-field instead is pretty much unusable, I guess who captured it had absolutely no clue about what he was doing.

    Thank you very much for having shared them, looking forward to try the far-field at higher volume tomorrow with my atomic CLRs, I guess it will sound even better thru those speakers.

    Now I just hope more reflection-free far-field IRs reach the market, I've tried a few of them over the last few years but most (if not all) of them clearly had some comb filtering caused by reflections.

    I have one question for you Jay if it's not too long/hard to explain:
    I had the impression that if I apply the minimum phase transform to your far-field IR the sound changes noticeably and becomes a bit "phasey" while with most close-mic IRs the difference is almost impossible to hear (unless they contain huge room reflections).
    Why is that happening? Maybe something to do with the ground-plane measurement or is it just that particular speaker not being close enough to a minimum phase system?
     
    Last edited: May 22, 2019
  4. yeky83

    yeky83 Member

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    That's interesting. Perhaps it's in part due to the greater presence of the "construction of the cab" part of the far-field sound that Jay talks about in post #102? No idea.
     
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  5. Jay Mitchell

    Jay Mitchell Member

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    I've said this many times: no speaker in an enclosure is even approximately a minimum phase system. There is never a reason to apply a minimum phase transform to an IR of a guitar speaker.
     
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  6. Jay Mitchell

    Jay Mitchell Member

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    I won't say anything about its origin except that it ain't "fake."

    I'd be inclined to guess the same thing.
     
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  7. Jay Mitchell

    Jay Mitchell Member

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    Thanks to the folks who are reporting their experiences. Hopefully we'll hear from more in the next few days.
     
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  8. Mark Al

    Mark Al Member

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    I also tested out three IRs from Jay today, which I asked him via PM and Jay kindly shared with me. I was instantly wow-ed by one of the IRs, it's easily one of the most natural sounding, balanced IR I've heard in a long time (I am no stranger to IRs, owning tons of IR from OH, RedWires, Celestion). It is almost entirely void of the typical boomy lows and hyped highs from near field IRs. It's balanced and rounded, it worked really well for Fender tones, and there is minimum amount of reflection I can hear from that IR as well. It's just great!

    I have no problem identifying one of the other IR as the near field IR, as I am quite familiar with the typical NF sound signature. And the last one is a far field IR with TONS of reflections, rending it almost useless.

    Immediately, I asked Jay, where do I find more IRs like this!! I know it's very limited experience with one particular far field IR, but I am definitely hooked, this far field IR sounds so much more natural, balanced and closer to the AITM feel. Man, we need more of those, please :)
     
  9. Jay Mitchell

    Jay Mitchell Member

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    What I'm seeing so far is a direct correlation between the graphic data I have presented and the audible characteristics of the IRs as identified by the auditioners. I've worked with this kind of data for decades, so the correlations are well-known to me. It would appear that they are also sufficiently obvious that the "average person" can detect them and connect them to the data I published, ergo there is a purpose in presenting "theory" (actually hard data based on proven principles) in discussions about sound.
     
  10. Chocol8

    Chocol8 Member

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    Is one of these 3 IR’s the Atomic Fender one posted earlier? I downloaded that one to test, but if there is something better I will send a PM.
     
  11. hippietim

    hippietim Member

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    Jay sent me the three IRs this evening. I have limited time to test. I loaded them on my AxeFX III and used the Deluxe Reverb factory. I turned off the reverb and loaded all three IRs in the cab block with default settings. I tested with my PRS PS Brent Mason which has a great mix of humbucker and single coil sounds. I only had time to listen with my Genelec monitors.

    There is no question which IR was not Jay's. That thing sounded terrible. There was a truly bizarre resonance thing happening like a cheap acoustic guitar simulator with a very brittle top end. This IR was harsh with any amount of gain from the amp. Using a drive pedal was completely unusable IMO.

    Ok, now the good. Jay's IRs are freakin' great. Really. Either one was usable with no adjustments to the preset. The edge of breakup sounded just like a DR should sound - a little angry but still keeping it together. The clean tones were really nice when I switched to singles or rolled back the volume. The high end was thick like a Fender should be with the volume opened up to the point of breakup when you dig in. The low end held together really nice. The two combined sounded very good together - if I had more time I would have experimented with the mix. I tried the drive pedal in the preset (sorry I don't recall which is used). I got exactly what I would expect from a DR - good top end crunch, the mids more pronounced but smooth, and the low end stayed tight.

    Bottom line for me is that Jay's IRs capture the essence of a DR cab and have a natural resonance. They really want to make me just play the guitar - unfortunately, I need to go do grown up stuff for a bit before I crash.
     
  12. Dave Merrill

    Dave Merrill Supporting Member

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    So this sounds promising. People are swapping these into their regular modeling rigs and noticing a real difference. That's really great.

    Jay, you might have a side business there if you weren't opposed to it. Seems like musicians would appreciate it too.
     
  13. Pat6969

    Pat6969 Supporting Member

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    Seems there’s something to be said for knowing what you’re doing!
     
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  14. Jay Mitchell

    Jay Mitchell Member

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    No. I have not shared that one in wav format.

    It's not a matter of "better." Of the three IRs I'm making available, two are of the same cab, taken with the same mic. One is close-mic'ed, the other was taken with the mic at 2 meters. It's an interesting comparison with no uncontrolled variables that is not available elsewhere.
     
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  15. Guitardave

    Guitardave Supporting Member

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    I'm curious to try them. Not sure if you already posted it but what speaker is it?
     
  16. BINGEWOOD

    BINGEWOOD Member

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    Thanks for these IRs Jay. I think they are great examples to help get the concepts and graphs in the thread across, and two are a lot of fun to play through/sound great!

    I prefer the one I think is the far field so thanks again for this information/lesson and the IRs.
     
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  17. The Trout

    The Trout Member

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    Jay, any chance to try one of your far field IR in .wav? Like many around, I have thousands of near field IRs but they all sound like s**t in live conditions IMO, so much that I finally decided to bring back my old PDI-03.
     
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  18. Cool Hand Luke

    Cool Hand Luke Member

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    This echoes my sentiments perfectly. Just a bit better articulated. I also got the three IRs from Jay and this was my response to him in an email I sent right after testing them out briefly:

    *********************************

    Alright,

    I couldn't help myself. Late last night after finishing the last episode of Game of Thrones I had to give the IRs a try. Being at home I was limited to using my headphones (which is far from ideal - I know) and give them a go. The headphones are Beyerdynamic DT150s so they are decent without the typical exaggerated bass and treble that many "hi-fi" headphones suffer from (IMO).

    Anyway, I suck at these kinds of things so I will probably guess all the IRs wrong. However, I do have definite preferences.

    B) Is very loud and sounds messy and brash to me. I did not like that one at all. I think that is the third party IR.
    A) Sounds pretty good but I think it is a bit bassy and it's got a bit of hollowness to it. I think this is the close miked one of yours and that the hollowness is caused by the reflections in there.
    C) Sounds really good. It sounds like an amp sounds. I think that is the far-field one. With IRs like that there is no need to have a million taken of each speaker with different microphones at different angles, distances, etc. It just works. Now, this may all be self suggestion but I really look forward to trying this IR through my Headrush.

    Thanks,
    Thomas
     
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  19. dlc86

    dlc86 Member

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    Ok so maybe the right question is: why most raw close-mic IRs seem to be very close to their minimum phase version?
    Is that something caused by the close-micing itself?

    I probably chose the wrong word. With "fake" I meant it is an IR that is not what it's advertised to be: a far-field IR (which by definition should be reflection-free)
     
  20. Chocol8

    Chocol8 Member

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    I don’t think that is the definition of far field. I would have taken far field to mean the mic was placed far enough back to capture the entire cab/speaker rather than be pointing at a specific spot on a specific driver. More than a few feet as opposed to a few inches or less for close mic’ed.

    It would only be reflection free if it is recorded in a large/open space with the mic on the ground. I used to measure home theater subwoofers this way. We would put the sub in the middle of an empty parking lot and lay a calibrated measurement mic on the ground 2 meters away. The sound would still reflect off the ground and back up, but since the mic was laying on the ground it would not pick up the reflections. Measured this way the subs had much less low frequency response but also much smoother curves than you would see in room. Most importantly for us though, the measurements were consistent for apples to apples comparisons and not dependent on the room, placement in the room and mic placement.

    I never even thought about doing this for guitar IR captures but it makes a lot of sense. The extra challenge is that we didn’t care about environmental noise above 120 hz but for guitar cabs you are going to want an extra quiet parking lot or a very large room.
     
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