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Reproduction of timbre

Discussion in 'Sound Science' started by old tech, Apr 23, 2019.
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  1. gregorio
    1. I'm talking about the "best way to do it" you also are talking about a "best way to do it", the problem is that your way is not the best way! "Regular people" either don't do anything at all or they just use the built-in auto systems, so neither of us are talking about regular people but people who take it more seriously than "regular people", audiophiles and others for example.

    2. Apparently not according to you, because what you're advocating is a "way" that doesn't achieve the best sound! The "way" that I'm talking about can achieve the best sound and it doesn't cost much, just a cheap measurement mic and free software (which many who take it more seriously than "regular people" have) but it's quite a complicated process with various pitfalls, which is why I don't generally advocate it.

    3. So based on a single personal experience, you're extrapolating what's the "best way" for everyone, without accounting for the actual issues involved. Exactly what audiophiles so often fallaciously do!

    Again, you're doing exactly as predicted and exactly what you yourself so often argue against: Defending your assertions at all costs, regardless of the actual facts and multiplying the contradictions!

    bfreedma likes this.
  2. bigshot
    I'm talking about the things you can do with a typical AVR. Do you have one in your system? Did you use Audessey or something like that to set it up? This is what I have to work with. It's what most people with 5.1 systems have to work with. That's what I'm talking about. The next step above that is a miniDSP. I might get something like that someday and start all over from scratch. I don't know if I would need to do tweaking beyond the measurements with that. Maybe.

    I noticed something interesting about the resonant frequencies in my room last night. They appear to be below 20Hz. I was watching a Japanese horror movie and in a silent scary part of the film, my walls started buzzing. Whatever is inside the walls was vibrating (Insulation? 2x4s? I don't know). In any case the audio was stone silent to my ears- just the walls were shaking. Then I could hear the buzzing slowly shift away from the walls to the phonograph's resonant frequency. Eventually it became an audible ultra low hum and all the buzzing disappeared. I guess they put a bed of sub audible bass in the sound track to just get the air vibrating in the scary part. Horror movies are the only things I run into resonant frequencies with. That must be an established technique. This is the only time I've heard it totally isolated like that. Usually it comes along with a normal audible bass rumble. I wonder if they intend for the walls of movie theaters to start making noises? When I was a kid I saw Earthquake in sensurround and plaster fell down off the ceiling of the theater.
    Last edited: Jul 29, 2019
  3. bfreedma
    Or maybe you have a large dip around the crossover point and don’t know it. Given that you clearly have the knowledge to do it and a lack of visibility to if and how the issue was resolved, I struggle to understand why you don’t take measurements to see what’s actually happening rather than relying on what you think is happening. At minimum, you walk away confirming you’ve addressed the issue. If most cases, you can make substantial improvements with a little effort.

    IME, most mixed use rooms have numerous nulls with a single sub, even in its “best” position. While multiple subs may be harder to calibrate, they tend to solve far more issues than they cause, particularly when calibrating for more than one small MLP.
  4. bfreedma

    Very few cinemas are reproducing bass under 30hz and most cut off above that. Modern shared wall multiplexes don’t get great feedback from the viewers of the romantic comedy when the theater next door is resonating bass through a wall far too thin to attenuate it significantly, let alone block it.

    This is not intended to knock your sub as it’s a competent unit, but have you ever really confirmed it’s output? I don’t think you’re getting significant output near or below 20hz unless you’re seeing some serious cabin gain.
  5. bigshot
    Wouldn't a dip at the crossover show up in a tone sweep? Lack of bass definitely isn't the problem in my particular room. It's bathed with bass. I had a guy who was an engineer from Dolby visit once, and the one thing he commented on was how solid the bass was. Could a peaked roof have something to do with evening that out? Or maybe it's some sort of technical trick by Bob Carver. I've never had to address that. manually

    The EQ in the Sunfire sub is all internal and automatic. I don't have control over EQ from the AVR because the sub is powered by itself.

    The main things I've adjusted by ear are the high end rolloff (I don't like things too bright- that is a personal taste because I play a lot of old music that isn't always well filtered), a little broad Q boost to the middle to give it more "in your face" (not sure how to describe that any other way), and the crossover to the sub in the mains. There is a upper mid notch that the auto EQ put in. I played with it to see what it was doing and liked it, so I left it alone. The centers and rears have their own curves because they are totally different kinds of speakers. I don't think I did much to change the auto EQ on those, I mainly adjusted the levels on them.

    Interesting about the bass in theaters. That must be a special treat just for the blu-ray audience.
    Last edited: Jul 29, 2019
  6. bfreedma

    It can be hard to identify a dip at the crossover point by ear and having one wouldn’t cause a lack of bass (other than at the cancellation point). I’ve heard many home theaters with more bass overall than needed that still had cancellation issues. The Carver subs don’t anything wrong, but they also don’t have any special sauce that other vendors with onboard EQ don’t have. And they can’t break the laws of physics. That said, it’s possible you have a room that’s very conducive to bass reproduction but there are too many factors involved to determine it from your description.

    Why not get a mic and software and see what’s happening? For a small investment, at worst you waste a little time and money. At best, you may find some significant improvement.

    Edit - are you sure your AVR isn’t also EQing the sub? The fact that it’s self powered isn’t a limitation, so unless the Yamaha EQ simply doesn’t address the sub, it should be including it in the cal. General best practice is to run the sub’s internal calibration, then run the auto EQ routine on the AVR. That’s how I’ve found it to work best with my JL’s which are also powered and have onboard EQ.

    I don’t know what Yamaha you have, so can’t say for sure that it’s EQing the sub, but the only AVR EQ I’m familiar with that didn’t is the older version of Pioneer’s MCACC.

    Edit 2 - yes, you can definitely dig lower with a good HT sub than what you get in theaters. Sometimes significantly so. Unfortunately, some studios, Disney being the main culprit, are dramatically reducing bass on BR as they continue to optimize for soundbars with small bass modules. It started about 2 years ago. Before that, some of the “big” movies had amazing bass available for those with the capacity to reproduce it.
    Last edited: Jul 29, 2019
  7. bigshot
    I'll do that when I get the money together for a miniDSP. At this point, there is no way for me to manually adjust anything about the sub anyway, so even if I could identify problems, I couldn't address them. There may be null points in parts of the room where people don't sit or stand. That wouldn't necessarily be a problem would it?

    One interesting thing about the bass in my room... The back of the room has a bar area that is half the width of the room. The other half is taken up by a bathroom. The bar area, door to the bathroom, bathroom and shower form a shape pretty close to an exponential horn. When you play music and stand in the shower, there is a ton of bass. Good for singing in the shower!

    I think the high peaked roof might have something to do with the sound of my room. The angle of the roof directs overhead reflections to the opposite wall over the heads of the people in the room. It isn't like a flat ceiling that reflects like the floor, bouncing sound like a pool table bumper back into the room.
    Last edited: Jul 29, 2019
  8. bfreedma
    Lol at the image.

    The miniDSP is a great unit. For crossover phase cancellation adjustments, you don’t need it - if you do have a dip, it can usually be resolved by changing the AVRs setting for the subwoofer distance, essentially altering the delay to avoid cancellation.
  9. bigshot
    If the sub is right next to the main and in perfect phase, it would be mostly cancellation with the rears and reflection off the back wall, right?

    I wonder if there are null points over my head because the rears are high up on the wall? I guess there isn’t typically a lot of bass in the rears except for FX movies. And the way my furniture is arranged, there isn’t much wall reflection going on anywhere near the sitting positions. Most of it is over 5 feet up in the air.
    Last edited: Jul 29, 2019
  10. Glmoneydawg
    Most SPL meters are not very accurate/sensitive below 35hz or so....room size and wavelengths are probably an issue at low frequencies. ... i will let somebody better educated expand on that:)
  11. Glmoneydawg
    If anybody wants to experiment you can download Vandersteens "vandertones" off his website for free...120hz down to 20hz in small increments....pretty handy for getting flatter bass response in room....and finding things that rattle in your listening room lol.
  12. gregorio
    1. And as predicted, you're just contradicting yourself more and more! You are NOT talking about "the things you can do with a typical AVR", you have consistently talked about response curves; understanding them, calibrating to them, saving baseline response curves, comparing them and tweaking them, but typical AVRs don't give you response curves, all they give you at best is frequency output curves! So, if you're not using a measurement mic and software, where are you getting these response curves you're calibrating to, saving, comparing and tweaking?

    2. And again, more contradiction! What has "powered by itself" got to do with it? We're talking about the signal it's outputting and the freq response of that signal at the LP, not where it's power is coming from. So where is it getting it's signal from? If you're using a typical AVR then it's getting that signal from your AVR, not itself. Therefore you can EQ that signal from your AVR, unless of course your AVR doesn't have a manual EQ facility for the sub channel, in which case, you are contradicting your assertions and advice to others (which was to manually EQ your speakers relative to response curves)!

  13. bigshot
    As I said many times, I started out by using the Yamaha auto EQ with the measurement mike and I saved that out as a baseline response. I EQ by ear from there. My AVR's auto EQ only sets the crossover and level of the powered subwoofer. It doesn't EQ the LFE channel. However the sub came with its own measurement mike and its own calibration tool built in. I ran that when I got it, and I've never changed it because there is no way to display or adjust the curve manually.

    Maybe I'm not speaking clearly enough. You seem to have trouble understanding what I am saying.
    Last edited: Jul 31, 2019
  14. gregorio
    Yes, I am having trouble understanding what you're saying! I don't know of any AVRs that allow you to "save out" the response curves at the listening position for each speaker and even if your Yamaha AVR does, then your advice could only apply to those with the same AVR, not everyone! And, you stated "With me the most important thing is to have a saved baseline response to compare to. Then you can easily compare to see if your adjustments have made things better or worse." - but now you're saying after the baseline response you "EQ by ear from there", how do you "easily compare" your "baseline FR curves" to your ears? You can obviously only compare a FR response curve with another (subsequent) FR curve, otherwise you are literally comparing different things!

    And again bigshot, you're defending at all costs, even at the cost of contracting yourself even more. This is following the exact same course as the stereotypical disagreement between an audiophile and the science/facts that we see so often here in this sub-forum, how could you of all people fall into that trap??

    Last edited: Jul 31, 2019
  15. bfreedma
    Not to pile on, but YPAO prior to the introduction of RSC (including subwoofer and parametric EQ) is a comparatively primitive autoEQ system. You really need to try something more modern/capable to address phase and time domain issues - you might be surprised how much better they are. If I recall the model of subwoofer you use correctly, it's EQ is limited to the 3 largest peaks/nulls, so given that your AVR isn't EQing the sub, there are likely some large improvements possible there with an updated auto EQ as well.

    I'm struggling to understand how you can address all of the issues not corrected by your version of AutoEQ by ear. Have you ever taken measurements of FR or a waterfall to see what's really going on?
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