Jump to content

SME

Members
  • Content count

    1,313
  • Joined

  • Last visited

  • Days Won

    68

Everything posted by SME

  1. SME

    Horn length extension on Othorns?

    I see (now). Some details in the photo are hard to make out, what with all those huge boxes in the way. 😉 I think this is key. Models in Hornresp and whatnot are helpful to understand what happens in an idealized 2pi space, but when you stuff 8 Othorns into a tiny cinder block room whose dimensions are smaller than most of the wavelengths of interest, much of that goes out the window. How much footprint does that well and sump pump take up? I don't know if there is space for this, but what happens if you arrange them into two groups of four with all units firing into the front wall? Each group is two units wide and two units high and the width between the two groups is twice the width between each group and each side-wall. I'd also invert the unit on top so the mouths are closer to the ceiling, and maybe put them up on platforms to get them closer to the ceiling for better symmetry. Is there room enough in the left corner for that to work? I'm guessing the room is maybe 12 feet wide? So I guess that means 12" between the side wall and each group and 24" between the two stacks. Maybe that's too close. Or perhaps it works if there is enough distance to the front wall? Another option may be to cluster all eight (or just six?) subs in the center, still firing everything toward the front wall but forcing all sound to exit along the side-walls. In this configuration, the cabinets could be perhaps be angled to create expansions in order to reduce high order resonances and possibly boost output even more. Obviously, both of these options will work much better if the ceiling and right wall gaps are closed. Anyway, just throwing out more ideas here. I know if I had that kind of appetite for bass and a dedicated room, I'd probably just build my system into the structure itself.
  2. SME

    Sundown ZV4 18D2 - sealed enclosure

    Lower crossover can be easier to integrate because the wavelengths are longer so interference is more likely to be constructive. However, every situation is different, and there are pros and cons to different approaches. I wasn't sure how low your mains could go. Some other guy on here with horns was pretty much set on using 60 Hz, and I think I might have gotten you two confused. If your subs play well together to higher frequencies, it can often be helpful to cross above 80 Hz. I cross at 100 Hz FWIW, and in fact I currently have MBMs behind my sofa that contribute up to about 150 Hz on the FL/FR channels with optimized DSP to make sure everything plays together in phase. Bass localization is not an issue at all, but I'll probably change this configuration at some point in the future.
  3. SME

    Horn length extension on Othorns?

    EIGHT Othorns?!?! I don't doubt he broke windows. To be frank, if he is so concerned about getting the most performance possible from 8 Othorns, I suspect his health might legitimately be in danger, or else he just happens to like testing spaceship parts for launch worthiness in his spare time. To address the question directly, I am far from being an expert in these things, but what @StainlessSteve says here sounds right to me. The tapping effectively acts as a tune, where the horn between the driver and tap is 1/4 wavelength at the tuning frequency, below which native response drops with 24 dB/octave, plus the roll-off introduced by the requisite HPF to prevent unloading. In other words, any boost in extension achieved by reconfiguring the cabinets will be mostly overwhelmed by the natural roll-off of the systems. An optimized configuration could maybe help boost overall output though, and how the horns interact with the room boundaries is another variable. I think getting the mouths closer to the front wall is the right move, but I'd be reluctant to fire them into the center of the room because this will result in symmetric side-wall reflections that combine to create a deeper null along the center line of the room. Why not fire them into the side walls? This will minimize distance between the mouths and the most rigid boundaries. If smoother side-to-side positional response is desired, the horns could also be placed firing into the front wall in two-high stacks in a 4x1 configuration. Of course if the real goal is to get more extension, maybe he should just *upgrade* to Skhorn's which can be tuned a bit lower at the expense of some output. :)
  4. SME

    Sundown ZV4 18D2 - sealed enclosure

    Any boost you do sacrifices headroom, and if you boost in the wrong place, you can end up making the bass more resonant / boomy. Take measurements at multiple locations in the room and avoid EQing (boost or cut) anything that is not consistent from seat-to-seat. The averaging feature in REW can be helpful here. Note that you shouldn't worry about EQ until you've optimized distances.
  5. SME

    Sundown ZV4 18D2 - sealed enclosure

    I recommend going with what measures best. Another option to consider is to put the other sub on the left at the rear of the room, as laid-out. That will likely give you the best deep bass performance. However, integrating with the mains is likely to be trickier. It might work OK though if you are using it with mid-bass horn(s) and/or the XO frequency is lower.
  6. SME

    Sundown ZV4 18D2 - sealed enclosure

    In your room, the left corner is more beneficial than the right because there is no large opening near it like there is with the right side. The "other" left corner, against the left wall instead of the front wall, may be even better. From your measurements the two subs obviously work better if they use the same polarity. It also looks like some low end bass boost would be a good idea. Are these measurements done with the sub low pass filter active? I assume so because there is a lot of roll-off above 80 Hz. Also, in your second set of plots you are using a linear instead of log frequency axis. I suggest using a log axis for future plots. Also, it's helpful to be able to compare multiple measurements at the same time on the "All SPL" tab.
  7. SME

    Sundown ZV4 18D2 - sealed enclosure

    Where did you get that idea? In a symmetric room, placing them in similar locations on each side can help reduce the effects of room modes. However, in an asymmetric room, it doesn't make as much of a difference. There are pros and cons to different locations, and every room is different. For sub performance alone and especially when you have EQ available, I would say that the best location is in corners or more generally as close as possible to the longest walls in the room. From your picture, that would appear to be the corner on the left (if it were available). However, another factor is how well the subs integrate with the mains. For quite a lot of the range, the subs and mains will be having to play together, and placements near the mains can help with that. I also agree with @Infrasonic that your best bet is to try a few configurations and take measurements. This can be quite an involved process being that you have two subs and probably want the best integration with the mains too. Each configuration is likely to have its own optimal settings for the delay/distance on each sub. The optimal crossover frequency can also vary. How many configurations options do you have available? By the way, it looks like your left and right speakers are not the same distance from the center. Is this on purpose? Is your main listening position centered between them and it's your center channel that's misaligned? If so, then perhaps that's OK. Otherwise, you should probably move the left or right speaker so that they are the same angle relative to where you sit, even if that means bringing the right one more to the inside.
  8. SME

    Bulding the Room2 listening room

    By noise free, do you mean acoustic (i.e. fans), electric( i.e. hiss), or both? If you're open to plate amps, you might look at some of the lower power offerings from SpeakerPower. They work best with 4 ohm, however. I believe they are based on the ICE amps, so you may be able to find other amp designs based off of ICE in EU. (Most of the ICEs I think like 4 ohm more.) Finding anything that's acoustic noise free with that power level will be tough.
  9. SME

    Samps DS21 Build

    Can you run a slower sweep? That might help reduce the ripple. Otherwise, looks good. It looks like you hit the tune you wanted right on the mark.
  10. SME

    Samps DS21 Build

    The lower peak substantially depends on the suspension compliance, which is probably the least accurate T/S parameter given and the most likely to change with break-in as well as temperature and humidity.
  11. SME

    Samps DS21 Build

    Driver break-in may shift the impedance peaks ever so slightly, but it won't affect the tune, which depends only on the cabinet volume and port characteristics. Edit: I think you're closer to 21.5-22 Hz. The tuning frequency is precisely where the phase crosses zero.
  12. I would add that the low-pass filter on the LFE channel will tend to soften any clipping that's present there anyway. The most offensive clipping is that which occurs on the mains channels, but I have found that the relative offensiveness of the clipping depends a lot on the quality of the playback system. If the playback system has sufficient headroom, a good balance between low and high frequencies, and no substantial mid or high frequency resonances, then most clipping is likely to be fairly inoffensive. My older playback systems likely suffered from all three of these deficiencies, and clipping in movies tended to be quite offensive to the ears. With my system now, and especially if reshape the response (where necessary) to compensate content created for X-curve calibrated systems, most clipping I hear just sounds kind of like a dirty recording, as though some of the signal isn't getting through. The sound quality is still obviously degraded, but it doesn't offend the ears like it did before. It also seems like most movies these days use soft limiting and/or compression instead of hard clipping like in the bad ole' days. That's good because most people have playback systems that are not so forgiving.
  13. SME

    Inductance modelling

    I recalled wrong. I was probably thinking about how much to reduce Fs by and not how much delta Mms to have. Thanks for the correction. Adding an Mms of 60% of cone mass should reduce Fs by 20%, so that seems to be about the right ballpark.
  14. SME

    Inductance modelling

    Per the response there, it looks like your RSS is effectively infinite. That may be perfectly fine for the model, but I haven't looked at the details. I agree with the comment about the added mass being too high. IIRC, you want something like 10-20% of Mms or else the error are potentially high. Also, one issue with impedance measurements that may or may not apply here is that they aren't accurate unless the driver is mounted to a very rigid baffle and in a forward firing orientation. In an up-firing orientation as when set on a bench top, the parameters can come out very wrong. That's why I don't have any free-air impedance sweeps of any of the drivers I bought.
  15. SME

    Othorn - HT capable?

    You show a strong bias towards using horn subs based on the assumption that more headroom is always good. Of course more headroom is better, all else the same, but beyond a point, the differences are extremely minute. There are many factors that influence sound quality. Distortion and headroom are only a part of the picture, and in fact, they are barely relevant in a small room at the levels you are operating at. This is further supported by experimental evidence involving blinded listeners. In addition to headroom, horn speakers have other characteristics that give them their unique sound vs. other types of speakers. Key among them is the controlled and limited dispersion of sound. In contrast, horn based subs don't offer much more dispersion control than their sealed and vented brethren do. At low-to-moderate levels, the difference in sound between different types of subs is *much* more similar than the difference in sound between horn and direct radiator speakers. Intuitively, it may seem that use of horns on the bottom end will provide a better "sound match" to the mains, but this is not at all true. I already outlined the factors that come into play, which are of far greater importance than the level of distortion at the levels you are playing at. The importance of room modal resonances can't be emphasized enough in your case, given your brick wall construction. Look, horn subs should work just fine for you, with the caveats you are already aware of. It's just that, without giving attention to other aspects of the system, replacing your sealed sub with a horn or two (assuming they are co-located) is unlikely to have much impact on your sound quality. Maybe that doesn't matter to you. It's remarkable how many people listen with their eyes rather than with their ears. The saying goes, "seeing is believing", and experiments shows that most audiophiles are strongly influenced by the visual sense when evaluating the "sound quality" of equipment. If you really want the best sound quality, I suggest you start by investing in measurement system so that you can see what the bass response is doing in your room. I would also say that EQ capability for the sub is a must. Maybe the SVS SB16 has that built in. Knock down the worst room resonance or two, and you'll likely hear a very different sound, which could be a game-changer. Here's another thought. If you want to maintain more controlled dispersion into the lower frequencies like your main speakers have, why not build some sealed sub arrays? If you give you them a lot of volume, you could probably use fairly inexpensive drivers. You could stack the subs on top of your mains or maybe invert the mains and put some drivers underneath and some on top. For inspiration, check out @Infrasonic's system here. By spreading out the bass radiators, he is able to reduce room interaction considerably, and the sheer number of drivers gives him enormous headroom. FWIW, I bet he plays his system well above 110 dB.
  16. SME

    Othorn - HT capable?

    This doesn't solve the phase match problem. If one uses a textbook electrical LR4, then the phase shift of the high pass and low pass filter will be identical vs. frequency. However, unless the speaker and sub(s) are ruler flat throughout the crossover region and co-located, they likely won't be phase-matched to begin with. The THX crossover was developed assuming the mains were sealed and had a natural Qtc=0.707 (Butterworth) 2nd roll-off. Two cascaded 2nd-order Butterworths makes an LR4, so the THX crossover applied a single 2nd order Butterworth to the mains and a full LR4 LPF to the subs. Provided that the subs didn't roll-off anywhere within the crossover region, that the mains behaved precisely as specified, and that they were co-located such that room effects applied to each equally, the result was ideal. In reality of course, "bass management" is a stinking mess. The whole point of it was that one could put the subs somewhere better for sub bass, but often the "better" locations are not so good for integrating with mains, especially where multi-listener is a priority. And of course, very few mains are sealed with perfect Qtc 0.707 and Fb 80 Hz. Any significant deviations from there substantially influence the phase response in the critical crossover region. Most mains these days are ported and tuned well below 80 Hz, so they have only slight phase shift at that point. They would do better with a full LR4 HPF, but few AVRs / processors seem to offer more than one XO type. My Denon AVR has the THX 2nd order 0.707 HPF baked in, which totally destroys the bass-managed mid-bass response with any speakers I've owned. The LFE response may measure picture perfect, but the mid-bass response of the other channels looks like trash. Also, how many subs are actually flat through the XO? Most of the beefier drivers are already dropping off from inductance effects. Sad to say, home theater "technology" is still stuck in the 90s in many respects. Great sound pretty much requires extensive customization, as I've learned over the years, and the affordable options for doing so leave a lot to be desired.
  17. Is the YouTube version sanitized or something? Just going by ear here, but I'm not noticing much bass at all. There seems to be a tiny amount of content around 20 Hz, but otherwise it's just mid-bass and at fairly moderate level. It sure has a lot of distortion though. If that music is pushing your sub too hard, you don't want to even try playing a movie until you figure out what's wrong.
  18. SME

    Othorn - HT capable?

    To be clear, @lilmike 's horn designs appear to be very good. I just wanted to point out that there's a lot more to good sub performance and good integration than what type of alignment is used. As I detailed above, you might want experiment with different (higher) crossovers. You emphasized integration with the mains as a high priority, and I'm arguing that good integration with mains has more to do with working around room effects. I didn't explicitly mention it, but phase match between the mains and subs is also crucial. This is partly addressed by optimizing the sub delay, but that only insures a good match at one (usually the crossover) frequency. Phase match can be tricky to get right when the mains roll-off rapidly near the XO frequency as yours do. I believe front-loaded horns like your mains exhibit 24 dB/octave roll-off below their lower limit, similar to vented cabinets. A lot of people try to cross vented mains at least half-an-octave higher than the point that they roll-off. So for example, you might consider crossing at 90 Hz instead of at 62 Hz. I personally cross at 100 Hz, even though my vented mains are tuned to ~45 Hz, because anything lower than 100 Hz just sucks in my room. Yes. Sealed subs are expensive for the headroom. How horns factor in depends on how much it costs to build the cabinets. They are complex enough that they could be a substantial part of the overall cost. For home theater, I think flat response with strong output to 15 Hz is a good sweet spot, and it's not difficult to achieve in most instances. While 15-20 Hz is not as substantial as the content above 20 Hz, I believe it still contributes a lot. Below 15 Hz, returns diminish rapidly as price and/or complexity also rises rapidly. Below 10 Hz seems to be hit or miss as perception of that content seems to primarily depend on how the floor responds. A 20 Hz TH can maybe make some sound at 15 Hz, but it won't play flat to 15 Hz unless your room has a big bump there. A 25 Hz horn has no business even trying. Keep in mind that unlike FLHs like the F20, a TH *requires* a high pass filter to protect it from unloading and avoid heavy distortion and/or permanent damage.
  19. Thanks for the offer, but it'll be some time before I'm ready to do serious testing on other systems, at which point I'll need to be present to listen to the results myself. Of course, if I move to Europe or something, it could happen sooner. A flat in-room response will probably not give the best sound. At the very least, you'll probably want 5-6 dB of bass boost centered around 80-160 Hz. You may also want a more gradual slope (i.e. 1 dB/octave) a ways above and below that point. Feel free to experiment, of course. I'm not aware of any online samples from Floyd Toole's book, but if you are curious, I highly recommend buying it. In my opinion, it's the best book on the subject of sound reproduction, particularly for small room systems. A lot of stuff in there seemed counter-intuitive to me when I first read about it, but my experience over time as led me to change my mind and conclude it was correct.
  20. Those look interesting. I'll definitely read them when I get the chance. The first article I opened (most popular) is dated 1998. Surprise surprise. This is hardly a "new" problem. The latest edition of Floyd Toole's Sound Reproduction book also has an entire chapter dedicated to discussing cinema sound where he remarks about the 2 kHz knee among other issues. Toole is consulting with an industry group that has recently been studying the problem with the aim of eventually establishing new SMPTE standards to address the problems with the X-curve. Toole's and Harman's recommendation seems to be to calibrate smoothed in-room response to a target that looks more like the Harman curve was is optimized (at least in theory) for "anechoic flat" speaker response cinema rooms and listening distances. While I think this approach would lead to an incremental improvement, it's still less than ideal. For starters, when people talk about frequency response, they don't bother to specify *how* the response was smoothed and *what form* was smoothed. These details actually matter a lot as far as the end result is concerned. For starters, one can choose a smoothing kernel which can be a flat-top ("moving average"), which is easiest to implement. Or it might use some kind of curve, for example a gaussian, which provides a smoother looking end result. As for what form, one can smooth the magnitude, the power, log-magnitude (i.e. the dB value), or the complex amplitude (where magnitude and phase are treated together as a composite 2D value). Power smoothing yields results most consistent with RTA and other continuous averaging instruments. Complex smoothing is actually mathematically equivalent to frequency-dependent window (!). FWIW from my testing, REW appears to do log-magnitude smoothing with a kernel that's similar to a gaussian. While it makes the data look prettier, it has a substantial effect on the end product. Furthermore, I have 99.9% confidence in the fact that fitting in-room response to any kind of target (even a room variable target) is suboptimal. Smooth in-room response should never occur in practice where any reflections are present, which means that in the process of EQing in-room response to be smooth, one actually introduces harmful resonances. How ironic! While I am a ways away from definitely solving this problem, I get the feeling I'm further along than anyone else at this point. It sure sounds like it.
  21. SME

    Othorn - HT capable?

    As I said, the question of whether horn subs have a "unique sound" that can be heard indoors is debated. Actually, that discussion assumes quality drivers and a competent build to begin with. Ideally, a sub shouldn't have a distinct sound at all beyond that which can be adjusted using EQ, but it's not hard to get a distinct (bad) sound from a sub that's poorly designed or poorly built. That goes for sealed, vented, and horn subs alike. As for what integrates best with your horn speakers, the question of sound characteristic is not especially relevant here. The sound depends far more on the effects of the room on the chosen placements for the sub(s) and listeners, any EQ or crossovers that are used, and the linear response of the sub at its upper limits. As I said, horn subs have more limited upper frequency capability, which makes them less flexible in small rooms. This means that you may be able to achieve better integration with the mains by *not* using a horn sub. It's really a minor thing, but I believe it's a lot more important than sound characteristic. In terms of sub design choice, the relevant questions are how much SPL you want with what kind of extension, how much space you have, how much effort you are willing to put into the build, and much money you are willing to spend. A pair of decent sealed 18"+ subs will give you plenty of SPL and extension for the modest listening levels you indicated. It seems to me that you've already made up your mind that horns are the only way to go. If so, then there's likely nothing any of us can say to convince you otherwise. And to be fair, you'll probably do just fine with horn subs like the F20. However, if you are serious about getting best integration with the mains or with choosing a design that fulfills your needs while better fitting your budget for money and space, you should definitely consider other design types. FWIW, I'm running 4 x high performance sealed 21" cabinets which get pushed to 125-130 dB from time to time. I chose them because I was space constrained, wanted a lot of extension, and was willing to spend the money.
  22. Sadly, even a cinema that's "designed, implemented and maintained properly", seems to be a rare occurrence. While my memory may not be completely reliable, my impression is that cinema sound quality (at least here in the States) has trended worse over time. I recall being fairly impressed by new cinemas built in the 90s and early '00s, but newly built/renovated cinemas I've heard in the last few years since are meh at best. I believe a big part of the issue is the X-curve calibration standard and a shift toward stricter adherence to the target. The standard actually allows for a +/- 3 dB deviation, which gives a lot of leeway to a calibrator to allow more bass and treble and to smoother the knee at 2 kHz, all while remaining "compliant" with the standard. However, I suspect this kind of manual tweaking is not done much anymore as cinemas cut labor costs associated with setup and maintenance including calibration work. Many cinemas are probably calibrated entirely automatically. I'm not opposed to automation when it actually works, but for audio calibration, current technology is not up to the task. I'm trying to change the situation by working on better technology. I have a very novel approach that is showing enormous promise, but it'll probably be at least a year before I can test it outside my own room. It also remains to be seen how much tweaking it will need to work robustly in a variety of different rooms. I do have confidence that I could eventually adapt it to work in all kinds of rooms, which would be very exciting. Then the challenge would be to get the industry to actually update their standards, but in the meantime, it could probably be marketed to cinemas directly where it could provide substantial SQ improvements via download-able X-curve re-EQ meta-data.
  23. SME

    Inductance modelling

    IIRC, WT2 exports to ZMA, which REW can import. I just tried it on one of my saved measurements, but I can't make REW calculate the parameters because all I have is an impedance measurement of the driver in the box. To calculate the inductance parameters, it must also calculate the rest of the T/S parameters which requires a free-air baseline and another measurement with added mass or in a test box of known volume.
  24. You have a point. When I said "unfiltered", I left it vague. The context was ULF, which could be informally taken to be under 20 Hz. Extension under 20 Hz seems to be pretty rare these days, but there is a decent amount of stuff that reaches to 20 Hz or 25 Hz, as you pointed out. Of course studios have no obligation to deliver audio that's flat to DC (or 3 Hz?). Though it's nice when it happens. I wish they'd do it more often, for the tactile transducer users among other reasons. I know a number of cinemas have transducers now. Although they may be mainly of the "shaker" type with poor extension.
  25. This thread is more about full-range content than bass, but it is content related, so I think it works best here. In the future, I may post this somewhere on AVSForum, but for now I want to keep it to a limited audience. As I've mentioned in the main LF Content thread, the X-curve calibration standard in cinema causes two major problems: Tonal balance that deviates substantially from neutral and from what is typical used (informally) for music production and what sounds good on a home system that is optimized for music. Inconsistent calibration between different dub-stages and cinemas. As I also noted, many UHDBR/BD/DVD releases these days have high quality home remixes that fix most of these tonal balance problems. This is true for most recent Disney releases these days (including, e.g. the new "Star Wars" and much recent Pixar and Marvel stuff). However, much legacy content as well as lesser quality home-remixes do not feature any re-EQ and retain the inverse-X-curve signature. The effect of X-curve calibration is to attenuate both high frequencies, via the -3 dB/octave slope in power response, and the low frequencies, which arises from forcing a flat power-averaged response even though virtually all speakers have a significant drop in directivity for low frequencies and what absorption is present in typical dub-stage / cinema rooms is also less effective at low frequencies. As a consequence of the altered tonal-balance, most mixes are likely altered to sound good in the dub-stage during the re-recording mix process in which highs and lows are boosted to compensate. The resulting mixes, in addition to translating unreliably between theaters, sound less than optimal when played back on a home system. The auditory symptoms are mixed. I find it easiest to hear the problems in the dialog. Sometimes only one of the excess highs or the excess lows is audible in the unaltered track because the boost dominates. For example, some cinema mixes, the dialog comes across very bright. In others, it comes across very boomy. Sometimes, the dialog seems relatively balance, in terms of high vs. low, but with the mid-range being relatively depressed, intelligibility often still suffers. Dialog is both much easier to understand and much more enjoyable to listen to when it's presented neutrally. Unfortunately, the required correction varies between track for both of the above reasons. Mixers don't necessarily attempt to defeat the X-curve alterations in any systematic way. Instead, they "turn various knobs" and listen until they are satisfied with the result. So the ideal filters to reverse their changes may vary between mixes. And because the X-curve calibration method isn't even consistent between dub-stages, EQ-adjustments that give good sound in one dub-stage may not work well in another. In fact, there's evidence that X-curve calibration doesn't even achieve consistency between the left and right vs. center screen channels vs. surround channels in the same dub-stage. The situation is a big stinking mess for sure. Nevertheless, even if the adverse effects of the X-curve standard on the mix cannot be perfectly reversed, it's possible with some rudimentary EQ to improve the sound quality of cinema mixes considerably. Now that I've finally achieved a stable, reliable audio reference in my own sound system, I've been giving attention to this problem. In this thread, I hope to document some of the candidate corrections that I've applied to improve the sound quality of various movies. I would encourage anyone with the required capabilities to give these a try and share feedback. To implement these requires the ability to apply various biquad EQ filters such as high and low shelves and Peaking EQs, ideally to the streams *before* bass-management. Though for my first pass, I'm applying the filters identically to all channels, so it should work fine to apply them after bass-management as well. One issue I imagine most people will have is that they have a limited number of free filter slots. The more filters used, the better quality correction that's possible. I will try to limit the filters to what's actually needed. Edit: I posted a candidate correction for "Wonder Woman". Sweet!
×