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Thread: Measurements, EQ, and what we actually hear

  1. #81
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    Default Re: Measurements, EQ, and what we actually hear

    Well, I'd have to buy a new laptop (REW doesn't work on an I-pad) and a mic. That would be about half of the total cost of the project.

    I've spent a few years moving the speakers, and experimenting with different amounts of toe-in, and right now they sound the best they've sounded yet. I've gone from very close to the back wall to where they are now, over 3 ft. away from it (this is already further into the room than would be ideal, so I don't think we could bring them out any more).

    The idea of finding out what's wrong but not being able to correct it seems like it would be frustrating to me - that's why I would want to get the equalizer first.
    Last edited by James; 04-24-2022 at 10:20 AM.

  2. #82
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    Default Re: Measurements, EQ, and what we actually hear

    Treating with an EQ is the last thing you should do. You don't even know what is "wrong" and there may not be any real issue.

    Find out what you want changed. Deal with it with placement and room treatments if you can...or even different speakers

    If you still are not satisfied, then you EQ to your liking.

    You are going down the EQ rabbit hole without even knowing what you want changed.

    My 2 cents. Good luck.
    -curtis

  3. #83
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    Default Re: Measurements, EQ, and what we actually hear

    As I said, there are a few things I hear that I'd like to improve a bit. And my wife hears at least a few of the things I hear, so she'd also hear improvements (she just doesn't care as much as I do about it).

    I've exhausted the placement possibilities, and the two Tri-Traps are all we can reasonably use in our living room. They did make an audible difference - reduced some of the room mode resonances and cleaned up the sound a bit higher up as well.

    After going through more speakers than I can easily list, and loving the Towers, the last thing I'd want to do is get different speakers (which would be much more expensive than what I'm considering).

    Thanks for your advice and good wishes.
    Last edited by James; 04-24-2022 at 01:18 PM.

  4. #84
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    Default Re: Measurements, EQ, and what we actually hear

    Just bear in mind that there will always be room modes unless you have a completely absorptive anechoic chamber. Roland/Boss's room at their Japanese headquarters is apparently unnerving in how quiet it is. In a consumer space, unless you're willing to treat it to take it out of the consumer and into the professional realm, you'll always have resonances, you'll always have nulls. All you can really do is just move them in the frequency domain by moving speakers or moving you. For room treatments, the most immediate bang for the buck to help things above midbass (say, 250-300hz) are broadband absorption on the side walls to kill first reflections. Down below 250-300hz you're looking at bass traps.

    Psychoacoustically, the human ear is more tolerant of nulls than it is of peaks, and the tolerance is modulated by the steepness of the Q of the null or peak.

    If you're trying to set up a totally locked-in stereo image, strict two-channel, the first thing I would do is solve the time domain problem: get the speakers equidistant to the main listening position first. If you have no room correction in your processing, just measure it with string and tape. Once that's done, if the speakers you're using are going to throw a nice 3d image, they should be doing it.

    Once that's solved, speaker rotation for toe should be evaluated. This is mostly just to EQ tweeter behavior. Once that's solved, scan with REW and look at the "All SPL" tab. At this point you're about to open a pandora's box. You're looking behind the curtain. Some of the things you'll see there you can fix, some of them you can't. Adjust whatever EQ mechanism you have, rescan. Rinse, repeat. Welcome to tweaker's paradise. Now you can read up on RT60 measurements, how to manipulate their decays, realize you don't need a second career and just be happy getting basic time and frequency response nailed down as much as you can.

    Sometimes just getting the distance right on a pair of big towers and throwing an amp at them is nirvana.

    Anyway, changing EQ with no way to measure is configuring blind. Being able to measure with no way to change it gives visibility into the potential issue with no power to change it. I would find either of these options really annoying.

  5. #85
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    Default Re: Measurements, EQ, and what we actually hear

    Hi Alleric,

    Thanks - I actually went ahead and got a mic and REW. Short version - it's very interesting, many of the things it found I had already heard, but not all of them, and it improved the system in audible ways.

    We had some corner bass traps before, and the speaker positioning was very good, based on years of moving/listening/using a test CD/repeat.

    I used the old B&K house curve, based on theoretical and audible grounds, after a lot of experimenting with others, like Bob Katz and Harman. The simpler implementation with fewer points worked better than a more complex one:

    20 Hz 0, 200 Hz -0.5, 2000 Hz -3.0, 20000 Hz -6.0

    None of the corrections were very wide bandwidth and the cuts weren't very large, confirming my sense that our system and the speakers were already very very good.

    There are a couple of things REW didn't measure (I'm not sure why) so I'm doing some final tinkering by ear with those.

    With the Behringer equalizer on, there is a very slight decrease in sound quality generally, but it's really only noticeable in direct comparisons - kind of a more crystalline sound, a bit harder and cooler. And the improvements in frequency response outweigh that downside.

    It was fascinating/fun/frustrating/confusing, and ultimately very satisfying.
    Last edited by James; 06-26-2022 at 01:49 PM.

  6. #86
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    Default Re: Measurements, EQ, and what we actually hear

    I should add that the unsmoothed measurements had sharper peaks and dips than I hear - it was the psycho-acoustically smoothed graph that looked a lot like what I hear, but not completely.

    I've always heard a couple of things that my wife doesn't hear, and it turns out I was right about them - that was nice.

    But there are also a couple of things neither one of us heard that show up on the smoothed graph, which is interesting/puzzling.

    And even the unsmoothed graph isn't bad, compared to some I've seen - the overall frequency response is about +/-7db, so no 20db peaks or dips.
    Last edited by James; 06-26-2022 at 03:25 PM.

  7. #87
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    Default Re: Measurements, EQ, and what we actually hear

    Quote Originally Posted by James View Post
    There are a couple of things REW didn't measure (I'm not sure why) so I'm doing some final tinkering by ear with those.
    What, specifically, were the unmeasured things?


    Quote Originally Posted by James View Post
    I should add that the unsmoothed measurements had sharper peaks and dips than I hear - it was the psycho-acoustically smoothed graph that looked a lot like what I hear, but not completely.
    Considering that the peak and null "rhythm" accelerate massively as you go up in frequency, this is entirely normal. People often freak out when they see the initial unsmoothed REW spl curves, but this is commonly because they don't know how the math works concerning frequency and octave. Western diatonic music theory contains 12 semitones within a given octave, inclusive. Down between 10-20hz, each hertz almost contains a pitch on its own. That mess you see up north of 2k? Each of those peaks and nulls is a partial of a given pitch.

    The psycho-acoustic graph is pretty much the closest representation of what your system is doing compared to how you year it. For troubleshooting and configuration of a room, though, I highly suggest using Variable smoothing. This does pretty much the same thing, but in spots where you jaggies really matter it will amplify them graphically for you. Helps to localize issues you should actually care about.



    Quote Originally Posted by James View Post
    I've always heard a couple of things that my wife doesn't hear, and it turns out I was right about them - that was nice.

    But there are also a couple of things neither one of us heard that show up on the smoothed graph, which is interesting/puzzling.
    I can solve this one for you: your ears hear your room differently than a calibrated (or uncalibrated!) microphone. We want our rooms to play "flat" or match one of many house curves (Tool, HK, whatever). Your mic can show you all day that you hit that correctly with your config, but you will always hear it differently. Human ear, it does not have flat sensitivity to the frequency range humans can hear. What makes it worse is that the curve we actually hear varies at different SPL. This is is where the dynamic EQ built into the DSP of Denon receivers is solid gold. You tune your room at or near reference SPL, which is way louder than most people listen to things, then let Dynamic EQ be that magical DSP bridge to your human ears.

    Quote Originally Posted by James View Post
    And even the unsmoothed graph isn't bad, compared to some I've seen - the overall frequency response is about +/-7db, so no 20db peaks or dips.
    You're telling me your All SPL graph, unsmooth, shows no peak or null greater than 7db? Especially up past 2k? Peaks, that can happen. Nulls? If that's legit, buy a mixing desk and and charge mastering time per hour.

  8. #88
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    Default Re: Measurements, EQ, and what we actually hear

    There's a room mode at about 74Hz, and another one at about double that, that the measurements didn't show. But they're definitely audible on plucked double bass and plucked lute/guitar.

    Yes, I used variable smoothing for the eq filters - that's what REW recommends.

    I'm not sure I understand that part yet (I understand the bit about different volume levels). If our ears hear differently from mics, which I believe, then why use the mic to set the filters? Are we over-correcting somehow for things we don't need?

    Yes - I used a moving mic technique right about at our listening position, going across our couch from one side to the other, which covered both speakers to about the outside edges. I took about 160 measurements and used the average forever function. The unsmoothed graph is very smooth from 2k to 20K, with a flat to gently sloping downward curve down to about -5db at 20k.

    There were no recommended eq settings above 1K, with the B&K curve.

    Nice idea :-)

    The biggest irregularities are in the 100-200Hz region - there's a -5db cut at 120 and a -5.5db cut at 170.
    Last edited by James; 06-27-2022 at 07:35 AM.

  9. #89
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    Default Re: Measurements, EQ, and what we actually hear

    Quote Originally Posted by James View Post
    I'm not sure I understand that part yet (I understand the bit about different volume levels). If our ears hear differently from mics, which I believe, then why use the mic to set the filters? Are we over-correcting somehow for things we don't need?

    Because the mic has no psychology. The mic has consistency. The mic provides reliable validation of changes made. Bear in mind, there is no empirical "correct" or "incorrect" on a frequency response curve. Not everyone likes legit "flat". It can sound very thin, clinical. I happen to not mind that, but I also happen to not mind a 3db house curve. I also happen to not mind a 3db house curve with another 3db slope in EQ below 80hz.

    As for over-correcting things we don't need? That's a philosophical question. I can't answer that for you.

    Your nulls between 100-200? Those are likely your room jaggies. They are yours and yours alone. Love them. Embrace them. They are your friends forever (unless you treat the ever-loving crap out of your room).

  10. #90
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    Default Re: Measurements, EQ, and what we actually hear

    Right, I understand the personal preference thing for house curves. It's the measurements of the pycho-acoustically smoothed response before any eq that show things we don't hear that are puzzling.

    If we don't hear those, maybe we don't need to "correct" them with eq?

    The things I mentioned were peaks, with the eq corrections. But there are also some nulls, which I sort of understand aren't correctable with eq. Fortunately we seem to hear peaks more than dips, so it's not a big problem.

    It sounded great before, and sounds really great now, both on our test cd and with music - I think I can stop trying to improve things for a while (my wife will be happy about that :-)), at least once I get the room mode corrections done.

    I think I'm close with those - and they're bigger corrections than any of the REW ones.

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