Official Rythmik Audio Subwoofer thread - Page 1189 - AVS Forum | Home Theater Discussions And Reviews
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post #35641 of 41367 Old 10-16-2018, 10:00 AM
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I think sealed just integrates better with my system even when running hot or with strong bass content. Sometimes I don't realize that it actually playing louder than I thought.

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post #35642 of 41367 Old 10-16-2018, 10:59 AM
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This is a very good point. Those interested in a Rythmik subwoofer should be doing so mainly for the transient response. I have a pair of Ascend speakers for my mains with the RAAL ribbon tweeter and I want the exceptional transient response of the subwoofer to be able to match that well. Perhaps there is an inverse relationship between transient response and tactile response, where the better the transient response you get the worse the tactile response gets in some frequencies. If that is the case, then we would be seeking something that is not accurate to the signal, which I personally wouldn't want.

I do find this whole discussion very interesting, especially with my home theater mostly being used for movies. But, seeking after the perfect sub and conditions in the room (down to how the floor or riser is constructed) to improve the tactile response feels an awful lot like some two channel guys with trying to pair the amplifier, the cables and power cords with the speakers in just the right way to get a "synergy". Where if they just got good well designed neutral speakers, speaker cables and an amplifier and just EQed things to personal taste, then they would probably get there more quickly and spending quite a bit less money. Is EQ just the answer for reintroducing tactile response, if that is what we want?
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Consider the rest of the audio band where we hear better. In a well designed sealed dedicated theater room most go to the effort to put up acoustical panels (absorption and diffusion) to help give more even decay times of the sound in the room in a way that sounds natural to the ear.
We can measure to get a good sense of whether or not we hit the mark. The idea is that if the room is treated well, then the decay times (looking at waterfall plots) should be even at all frequencies with it gradually taking longer to decay as we get down into the bass region. If we were going to build a riser that resonates, wouldn't we want the decay times of that in terms of the vibrations of the floor structure to match the decay times of those same frequencies in the waterfall plots? That seems like it would be the most accurate. How would we construct such a floor? Is concrete just not the right material because it is too "dead" in terms of transmitting vibrations?
Hi,

I wish that I had answers to some of the questions that are being asked by you and others. Sometimes though, all we have are empirical observations, waiting for an explanation. Low-bass tactile sensations are a real phenomenon. We feel them all around us outside our home theaters. In nature, we feel them during an earth tremor, or a thunderstorm, or from a geyser erupting, or from something heavy hitting the ground. Where machinery is involved, we feel those low-bass tactile sensations from anything that produces tangible vibrations at the right low-frequencies.

I think that for many HT owners, divorcing the loud sound of low-frequencies, from the tactile sensations that we associate with those sounds, is sort of alien and artificial. I'm not sure that I have ever heard it expressed in exactly that way before, but I believe that most people who enjoy those sensations would agree with that statement. Section VII of the Guide, linked below, starts with an attempt to explain why we like bass so much. One of the reasons, in my opinion, is the tactile sensations that accompany low-frequencies. There are no comparable sensations which accompany higher frequencies.

I think that some of us are more susceptible to feeling various forms of tactile response, and I think that some of us may enjoy those sensations more than others. But, I believe that overall, TR is a meaningful component in our enjoyment of bass. Some symphonic pieces especially would be incomplete without those tactile sensations. And, when we turn our attention to movies, they become even more important.

One of the things that I point out in that Section VII, I mentioned, is that low-bass frequencies and tactile sensations in nature are typically not a good thing. The sound of a thunderstorm, or an earthquake, or an avalanche, is not something we enjoy. In fact, we react somewhat atavistically to them, with a sense of instinctive dread. Similarly, the sound of a large predator moving, or roaring, is terrifying rather than entertaining.

And yet, in movies, we can feel the cortical arousal associated with volcanoes, earthquakes, gunfights, explosions, etc while being entertained by both the visual spectacle and by the audio sounds and associated tactile sensations that accompany that spectacle. We get to be titillated without being terrified. I definitely think that the low-frequency tactile sensations which we instinctively associate with loud and low-bass sounds contribute to the overall effect. But, how much we like those sensations, and how much priority we want to give them in our movie viewing, for instance, is an entirely personal choice.

I completely agree with observations that the material construction of our home theaters can have a profound effect on, not only what we hear, but also on what we feel. The more solid and relatively inert the construction of our homes is, the more tactile energy it may take to excite us. And, the reverse is true for less inert structures. Not as much low-bass TR may be required to produce good effects.

I think that is particularly the case for people who are on suspended wood floors, which conduct low-frequency vibrations so well. Concrete over compacted soil is relatively much more inert compared to a wood floor suspended over a crawl space, or over a room below it. It consequently takes a great deal more low-frequency energy to feel the same low-bass tactile sensations on a thick concrete slab, in a brick house, than it does to feel those same sensations in a wood frame house, on a suspended wood floor.

I also wish that I had a better understanding of why some ported subwoofers are able to produce more overt low-frequency tactile effects than others. I would hope that some of the recent discussion will encourage some additional exploration of the issue. This discussion all commenced with the observation that the FV18 with a paper cone seemed able to generate more low-bass TR than the previous metal cone version. Whether or not that is a good thing or a bad thing, and whether there are negative trade-offs which accompany the ability to generate additional low-bass TR, are different questions, and entirely individualistic ones, in my opinion.

Regards,
Mike

GUIDE TO SUBWOOFER CALIBRATION AND BASS PREFERENCES

* The Guide linked above is a comprehensive guide to Audio & HT systems, including:
Speaker placements & Room treatments; HT calibration & Room EQ; Room gain; Bass
Preferences; Subwoofer Buyer's Guide: Sealed/ported; ID subs; Subwoofer placement.

Last edited by mthomas47; 10-16-2018 at 04:11 PM. Reason: Typo
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post #35643 of 41367 Old 10-16-2018, 03:54 PM
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Hi,

I wish that I had answers to some of the questions that are being asked by you and others. Sometimes though, all we have are empirical observations, waiting for an explanation. Low-bass tactile sensations are a real phenomenon. We feel them all around us outside our home theaters. In nature, we feel them during an earth tremor, or a thunderstorm, or from a geyser erupting, or from something heavy hitting the ground. Where machinery is involved, we feel those low-bass tactile sensations from anything that produces tangible vibrations at the right low-frequencies.

I think that for many HT owners, divorcing the loud sound of low-frequencies, from the tactile sensations that we associate with those sounds, is sort of alien and artificial. I'm not sure that I have ever heard it expressed in exactly that way before, but I believe that most people who enjoy those sensations would agree with that statement. Section VII of the Guide, linked below, starts with an attempt to explain why we like bass so much. One of the reasons, in my opinion, is the tactile sensations that accompany low-frequencies. There are no comparable sensations which accompany higher frequencies.

I think that some of us are more susceptible to feeling various forms of tactile response, and I think that some of us may enjoy those sensations more than others. But, I believe that overall, TR is a meaningful component in our enjoyment of bass. Some symphonic pieces especially would be incomplete without those tactile sensations. And, when we turn our attention to movies, they become even more important.

One of the things that I point out in that Section VII, I mentioned, is that low-bass frequencies and tactile sensations in nature are typically not a good thing. The sound of a thunderstorm, or an earthquake, or an avalanche, is not something we enjoy. In fact, we react somewhat atavistically to them, with a sense of instinctive dread. Similarly, the sound of a large predator moving, or roaring, is terrifying rather than entertaining.

And yet, in movies, we can feel the cortical arousal associated with volcanoes, earthquakes, gunfights, explosions, etc while being entertained by both the visual spectacle and by the audio sounds and associated tactile sensations that accompany that spectacle. We get to be titillated without being terrified. I definitely think that the low-frequency tactile sensations which we instinctively associate with loud and low-bass sounds contribute to the overall effect. But, how much we like those sensations, and how much priority we want to give them in our movie viewing, for instance, is an entirely personal choice.

I completely agree with observations that the material construction of our home theaters can have a profound effect on, not only what we hear, but also on what we feel. The more solid and relatively inert the construction of our homes is, the more tactile energy it may take to excite us. And, the reverse is true for less inert structures. Not as much low-bass TR may be required to produce good effects.

I think that is particularly the case for people who are on suspended wood floors, which conduct low-frequency vibrations so well. Concrete over compacted soil is relatively much more inert compared to a wood floor suspended over a crawl space, or over a room below it. It consequently takes a great deal more low-frequency energy to feel the same low-bass tactile sensations on a thick concrete slab, in a brick house, than it does to feel those same sensations in a wood frame house, on a suspended wood floor.

I also wish that I had a better understanding of why some ported subwoofers are able to produce more overt low-frequency tactile effects than others. I would hope that some of the recent discussion will encourage some additional exploration of the issue. This discussion all commenced with the observation that the FV18 with a paper cone seemed able to generate more low-bass TR than the previous metal cone version. Whether or not that is a good thing or a bad thing, and whether there are negative trade-offs which accompany the ability to generate additional low-bass TR, is a different question, and an entirely individualistic one, in my opinion.

Regards,
Mike



Regards,
Mike
This seems to be a big hole that could be filled by acousticians. It doesn't seem like it would be that difficult for them to be able to come up with a way to ensure that the decay time of the sound in the room (from waterfall plots) matches the decay of the vibrations in the bass region by suggesting plans for the construction of risers or subfloor. Take a company like GIK or Aurolex example. You can give them dimensions of your room and even get a UMIK-1 and and send them some waterfall plots and they can pretty accurately tell you which panels to put where in your room to give you even decay times. If you have a sealed rectangular room and move to another sealed rectangular room, you should be able to do the same thing and get a pretty similar sound from the same set of speakers.

But, with the same subwoofer moving from one sealed room to another could give you drastically different results in terms of tactile response, if one house is a new construction and the other is an older home. Or if one room was on the first or second floor and the other is in a basement. If it isn't possible for an acoustician to give detailed construction plans for how to build a riser or subfloor so that the decay time, of the sound would match the decay time of the vibration of the floor, then maybe they could develop tactile transducers that would be able to give consistent results. I'm a bit leery of wading into tactile transducers, because I wouldn't want the transient response of the tactile transducer to be worse than the subwoofer, which would be unnatural and pull you out of the movie as opposed to drawing you in. Much like if there is a slight difference of the audio and video, it is very distracting. After all I am purchasing a Rythmik subwoofer, because they have exceptional transient response.

Maybe I'll reach out to some of these companies (like GIK, Aurolex, etc.) and see if they already do something along these lines. About 10 years ago Gene had Aurolex give him detailed plans for making a riser that increased the tactile response, when you sit on it. But, he had already spent 10's of thousands of dollars with that and his is the president of Audioholics. I'm not just interested in increasing tactile response, but in a way that would match the sound waves and sound pressure in decay, which might be more difficult.
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post #35644 of 41367 Old 10-16-2018, 05:07 PM
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This seems to be a big hole that could be filled by acousticians. It doesn't seem like it would be that difficult for them to be able to come up with a way to ensure that the decay time of the sound in the room (from waterfall plots) matches the decay of the vibrations in the bass region by suggesting plans for the construction of risers or subfloor. Take a company like GIK or Aurolex example. You can give them dimensions of your room and even get a UMIK-1 and and send them some waterfall plots and they can pretty accurately tell you which panels to put where in your room to give you even decay times. If you have a sealed rectangular room and move to another sealed rectangular room, you should be able to do the same thing and get a pretty similar sound from the same set of speakers.

But, with the same subwoofer moving from one sealed room to another could give you drastically different results in terms of tactile response, if one house is a new construction and the other is an older home. Or if one room was on the first or second floor and the other is in a basement. If it isn't possible for an acoustician to give detailed construction plans for how to build a riser or subfloor so that the decay time, of the sound would match the decay time of the vibration of the floor, then maybe they could develop tactile transducers that would be able to give consistent results. I'm a bit leery of wading into tactile transducers, because I wouldn't want the transient response of the tactile transducer to be worse than the subwoofer, which would be unnatural and pull you out of the movie as opposed to drawing you in. Much like if there is a slight difference of the audio and video, it is very distracting. After all I am purchasing a Rythmik subwoofer, because they have exceptional transient response.

Maybe I'll reach out to some of these companies (like GIK, Aurolex, etc.) and see if they already do something along these lines. About 10 years ago Gene had Aurolex give him detailed plans for making a riser that increased the tactile response, when you sit on it. But, he had already spent 10's of thousands of dollars with that and his is the president of Audioholics. I'm not just interested in increasing tactile response, but in a way that would match the sound waves and sound pressure in decay, which might be more difficult.

I will be interested in what he tells you, but I think that the discussion of decay is a red herring when it comes to low-bass tactile response. The whole point of those low-bass tactile sensations is that they are somewhat sustained in nature. They are very different from the sharp/abrupt/percussive sensations associated with mid-bass chest punch.

I think that it would be very difficult to precisely correlate a sound (which would also typically be somewhat sustained) at 25Hz, or 20Hz, or lower, from the tactile sensations accompanying it, with sufficient acuity to distinguish the amount of decay in the tactile sensation.

GUIDE TO SUBWOOFER CALIBRATION AND BASS PREFERENCES

* The Guide linked above is a comprehensive guide to Audio & HT systems, including:
Speaker placements & Room treatments; HT calibration & Room EQ; Room gain; Bass
Preferences; Subwoofer Buyer's Guide: Sealed/ported; ID subs; Subwoofer placement.
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in my unusual situation due to room size I really have to crank up the bass trims and sub gain to get nice TR with music. say +8 on avr trim (-1.5) and 3 oclock on sub gain

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But, with the same subwoofer moving from one sealed room to another could give you drastically different results in terms of tactile response, if one house is a new construction and the other is an older home. Or if one room was on the first or second floor and the other is in a basement. If it isn't possible for an acoustician to give detailed construction plans for how to build a riser or subfloor so that the decay time, of the sound would match the decay time of the vibration of the floor, then maybe they could develop tactile transducers that would be able to give consistent results. I'm a bit leery of wading into tactile transducers, because I wouldn't want the transient response of the tactile transducer to be worse than the subwoofer, which would be unnatural and pull you out of the movie as opposed to drawing you in. Much like if there is a slight difference of the audio and video, it is very distracting. After all I am purchasing a Rythmik subwoofer, because they have exceptional transient response.
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I will be interested in what he tells you, but I think that the discussion of decay is a red herring when it comes to low-bass tactile response. The whole point of those low-bass tactile sensations is that they are somewhat sustained in nature. They are very different from the sharp/abrupt/percussive sensations associated with mid-bass chest punch
The challenge with TR is that we have no reference curve. @coolrda , myself, and others at one point were trying to determine what a Reference TR curve might look like. Like I said, I took a little sabbatical, but IIRC, we were leaning toward a downward sloping curve via the Vibsensor tool (mobile app).

About 2 years ago, I went to a KC GTG and was able to take FR and TR sweeps of the HT's on the crawl. Below are the results:

Spoiler!
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post #35647 of 41367 Old 10-16-2018, 06:04 PM
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I will be interested in what he tells you, but I think that the discussion of decay is a red herring when it comes to low-bass tactile response. The whole point of those low-bass tactile sensations is that they are somewhat sustained in nature. They are very different from the sharp/abrupt/percussive sensations associated with mid-bass chest punch.

I think that it would be very difficult to precisely correlate a sound (which would also typically be somewhat sustained) at 25Hz, or 20Hz, or lower, from the tactile sensations accompanying it, with sufficient acuity to distinguish the amount of decay in the tactile sensation.
I’ll let you know if I find anything out.


Or maybe we can just try to convince Brian to make a tactile transducer. Imagine having all of the controls on the amp, like a knob to adjust the damping and such. And knowing that it’s transient response would be equal to the subwoofer. I’d be first in line.
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post #35648 of 41367 Old 10-16-2018, 06:27 PM
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The challenge with TR is that we have no reference curve. @coolrda , myself, and others at one point were trying to determine what a Reference TR curve might look like. Like I said, I took a little sabbatical, but IIRC, we were leaning toward a downward sloping curve via the Vibsensor tool (mobile app).

About 2 years ago, I went to a KC GTG and was able to take FR and TR sweeps of the HT's on the crawl. Below are the results:

Spoiler!

I think it's important to continue to distinguish between low-bass TR and mid-bass TR. I know that you understand the distinction very well. Low-bass TR is primarily a movie phenomenon. I also think that we not only don't have any common ground as to what a low-bass TR curve might look like, particularly considering the fact that it would change with the room (as noted by Schrodinger) but we also don't know what the FR or decay rate of the TR should be, even if we tried to develop something based on average perceptions. What I mean by that is what is the TR decay rate in ms for a loud thunderclap, where lightning strikes nearby, or for a really heavy truck rumbling by, or for something heavy hitting the ground? Each one would change with circumstances.

When a sound mixer simulates those sounds in a movie, he makes the sounds however low, and loud, and sustained that he wants them to be in order to create the effect he is after. But, they are artificially reproduced or enhanced sounds, even if we did know what that precise natural sound and associated TR should be like. This isn't like the relationship between mid-bass sounds and tactile sensations, where we would at least have well known musical instruments (such as the decay rate of a kick drum) to guide us somewhat.

And then, our subwoofers, and our subwoofer boosts, and our rooms simply produce whatever TR that they produce, when those artificial effects are played in our system. As mentioned earlier, I really don't think that we could ever correlate the decay rate of the low-bass TR in ms, with the low-frequency sounds we were hearing. Our senses wouldn't be acute enough, even if we had some sort of standard to guide us. I don't believe we would ever notice or care about that kind of precision for movie special effects.

To some extent, our rooms are what they are, especially in mixed-use rooms. But, even in purpose-built HT's, room treatments will have very little effect on the frequencies we are discussing here. Where I think that we implement our personal preferences for low-bass TR, whatever they might be, is with the subwoofers we select, with the volume levels and subwoofer boosts we employ, perhaps with the wood risers (ala David Gage) that we put under our listening chairs, and with the use of tactile transducers.

I think that it's interesting to compare perceptions and preferences, and interesting to try to correlate those to the subwoofers which produce them. And, I think that it would be interesting to better understand the mechanism that allows some subwoofers to produce more low-bass TR than others. But, I don't have much hope for a meaningful reference standard for low-bass TR.

Regards,
Mike
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GUIDE TO SUBWOOFER CALIBRATION AND BASS PREFERENCES

* The Guide linked above is a comprehensive guide to Audio & HT systems, including:
Speaker placements & Room treatments; HT calibration & Room EQ; Room gain; Bass
Preferences; Subwoofer Buyer's Guide: Sealed/ported; ID subs; Subwoofer placement.
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Don't want compromises? Have both designs!
It's usually been frowned upon to mix ported and sealed, and you even mentioned the phase issues you can run into doing so. But, the idea is very intriguing. However, I think that if you have a sealed sub, the moment you introduce a ported sub into the room, you may as well go all ported, because you are going to lose what made the sealed sub desirable. Right?
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post #35650 of 41367 Old 10-16-2018, 08:34 PM
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I think it's important to continue to distinguish between low-bass TR and mid-bass TR. I know that you understand the distinction very well. Low-bass TR is primarily a movie phenomenon. I also think that we not only don't have any common ground as to what a low-bass TR curve might look like, particularly considering the fact that it would change with the room (as noted by Schrodinger) but we also don't know what the FR or decay rate of the TR should be, even if we tried to develop something based on average perceptions. What I mean by that is what is the TR decay rate in ms for a loud thunderclap, where lightning strikes nearby, or for a really heavy truck rumbling by, or for something heavy hitting the ground? Each one would change with circumstances.

When a sound mixer simulates those sounds in a movie, he makes the sounds however low, and loud, and sustained that he wants them to be in order to create the effect he is after. But, they are artificially reproduced or enhanced sounds, even if we did know what that precise natural sound and associated TR should be like. This isn't like the relationship between mid-bass sounds and tactile sensations, where we would at least have well known musical instruments (such as the decay rate of a kick drum) to guide us somewhat.

And then, our subwoofers, and our subwoofer boosts, and our rooms simply produce whatever TR that they produce, when those artificial effects are played in our system. As mentioned earlier, I really don't think that we could ever correlate the decay rate of the low-bass TR in ms, with the low-frequency sounds we were hearing. Our senses wouldn't be acute enough, even if we had some sort of standard to guide us. I don't believe we would ever notice or care about that kind of precision for movie special effects.

To some extent, our rooms are what they are, especially in mixed-use rooms. But, even in purpose-built HT's, room treatments will have very little effect on the frequencies we are discussing here. Where I think that we implement our personal preferences for low-bass TR, whatever they might be, is with the subwoofers we select, with the volume levels and subwoofer boosts we employ, perhaps with the wood risers (ala David Gage) that we put under our listening chairs, and with the use of tactile transducers.

I think that it's interesting to compare perceptions and preferences, and interesting to try to correlate those to the subwoofers which produce them. And, I think that it would be interesting to better understand the mechanism that allows some subwoofers to produce more low-bass TR than others. But, I don't have much hope for a meaningful reference standard for low-bass TR.

Regards,
Mike
Yes, I should have clarified. The quest for that you refer to as "low bass TR" is based off preference for the reasons you described. The intent would be to determine a TR curve that is more favorable for most when compared to other curves. Based on the subjective feedback of the KC GTG, the majority preferred a TR curve that had the highest vibration at the lowest frequencies, and slowly tapered off as it increased in frequency:

Spoiler!
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It's usually been frowned upon to mix ported and sealed, and you even mentioned the phase issues you can run into doing so. But, the idea is very intriguing. However, I think that if you have a sealed sub, the moment you introduce a ported sub into the room, you may as well go all ported, because you are going to lose what made the sealed sub desirable. Right?
What do you believe you lose?

With my setup, I take advantage of the sealed low frequency extension (5hz in my room), enjoy a house (or flat) FR, while still take advantage of the TR my FV15HP's provide in the near field.

This setup, is 100% movies.

In my room, phase issues (where it drops below the ported subs tune) are non-existent.
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Low-bass tactile sensations are a real phenomenon.
Harmonic distortion is also a real phenomenon. I often wonder whether and to what degree there is a disparate preference for more or less distortion in subwoofers among different enthusiasts. Some forms of distortion can make the sub sound fuller and I think some people likely prefer this fuller sound more than others.

I don't know the answer, but if two similar sized subs playing the same signal at the same output level produce a different tactile response, I wonder whether different levels of distortion could be contributing to the perceived difference in tactile response.
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post #35653 of 41367 Old 10-16-2018, 09:09 PM
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instead of distortion, think about ringing also...when I get the TR I want...ringing shoots all off the graphs. no ringing for me equals no bass in my space

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post #35654 of 41367 Old 10-16-2018, 09:59 PM
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Originally Posted by dominguez1 View Post
What do you believe you lose?

With my setup, I take advantage of the sealed low frequency extension (5hz in my room), enjoy a house (or flat) FR, while still take advantage of the TR my FV15HP's provide in the near field.
The low Q value of the sealed subwoofer, being better damped, will provide more articulate and detailed bass. However, I would think that will become harder to discern when blended with a ported sub with a higher Q value. Several people here commented a few pages back that a ported and sealed Rythmik sub, both set to high damping, is like the ported sub sounding like high, and the sealed sounding like "super high" damping. So there is a difference there.

But, it is an intriguing idea. Can we have our cake and eat it, too?

I don't believe it would work in my setup. I am using Dirac Live, which is measuring the sum of the two subs and applying EQ to a single sub channel, then into a Y-splitter. I'm not sure how EQ would work in this case. Any ideas?

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post #35655 of 41367 Old 10-17-2018, 12:41 AM
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Mike,


The paper cone version of FV18 has exactly the same bass extension, Q value of bass extension, and excursion limit as the metal cone verison. So we really need to be careful about drawing conclusion. I rely heavily on modelling (on both subwoofer drivers and subwoofer systems which are driver plus enclosure) to save my design time. I try to avoid tweaking. My explanation of the extra TR demonstrated at GTG is more from the efficiency improvement from midbass AND the subwoofer was not pushed beyond its capability. At GTG, playback SPL is at or near what our ears can bear. So headroom becomes very important and less extension gives more headroom. For every octave extension playing at same SPL, the excursion requirement is 4x. I really need to write this in big CAP letters. For the same SPL, the excursion requirement at 10hz is 4x of that at 20hz. So all sub drivers that are capable of producing SPL at below 20hz are long excursion drivers. That is from excursion point of view. Then from power consumption point of view, it is similar albeit it is not 4x. It is more like 2x. So playing a subsonic signal takes away amplifier headroom, especially at "competition" SPL level. Marc did all the level calibration and his familiarity of all the models making him perfect for the job. No roomEQ was applied, which was a wise decision. The impact of roomEQ to headroom is unpredictable. At the same time, that also makes our extension and damping setting switch effective in terms of trading off max SPL vs bass extension.


I still want to emphasize that the strength of our subs is the ability to reproduce the bass with details and articulation. The special effects of building collapsing or dinosaur footing are all synthesized. What is the reason gun shot sound from movies ALWAYS sound less impactful than the real gun shot sounds? It never sound like you are next to it. The real gun shot sound give you ear ringing afterwards. It is because there is a dynamic range limit the sound engineers need to work with. [PS: Of course several movies now actually add the afterwards ear ringing into the special effects which is really smart]. Under that constraints, the sound engineers need to make up by adding sufficient details in the synthesized effects. A building collapsing is not just one big boom. Otherwise they will all sound the same. How do we tell it is a 4 story building collapsing vs 20 story building collapsing? A skillful sound engineer can synthesize the sound based on his/her understanding of physics. The same thing is for dinasaur footing. We should observe when we walk, our heel lands first. So it is not a single boom for Dinasur footing. In the fly of phoenix, in addition to rumbling there are 100 things going on in that plane before the crash. Ideally, the strength of our subs should be their ability of hearing all 100 things working together instead of blurry 100 things or even some of them disappearing.

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post #35656 of 41367 Old 10-17-2018, 02:13 AM
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So it is not a single boom for Dinasur footing. In the fly of phoenix, in addition to rumbling there are 100 things going on in that plane before the crash. Ideally, the strength of our subs should be their ability of hearing all 100 things working together instead of blurry 100 things or even some of them disappearing.
This is exactly what I am experiencing since I have been using the F12s. You get abondence of detail and you can get a little more oomph by using low damping, which I do use for film only. For music I use high damping and the sub is actually engaged from around 50 Hz at - 6dB and then is flat from 45 Hz to 20 Hz.
I do not apply any eq only phase adjustment on the sub to get a better time alignment between subs and mains, which crossover at 45Hz, plus I filter the sub at 60 Hz as keeping the gauge higher produces a bump around 120 Hz although measuring the sub by itself shows the highest frequency being reproduced to be 100Hz (down possibly by 40 db). I belive that for music the most important things are having a good room to begin with and to integrate the right equipment for that room. The interaction between the two is so much more important than using esoteric cables.
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post #35657 of 41367 Old 10-17-2018, 08:48 AM
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The FR of a ported sub is the sum of that from woofer and the port and they are not always in phase. Here I attached 4 plots. First is FR plots of all 3: port, woofer, and sum. Next is the impulse response of all 3. The magenta is the port output and the yellow is the sum. The zero line is 3 division from the bottom (or the trailing response). As you can see woofer and port are not always in phase. This is not a surprise because below tuning frequency, the port and woofer are out of phase. For instance, at the end of second division, the port and woofer are out of phase and the sum has a zero-crossing 1/4 from the end of 2nd division. In fact, a good half second division has woofer and port out of phase. This happens again at the end of 3rd division into 4th divison.

As I already explained before if I stick a near-field mic to a 3" port on a 12" ported sub, the measurement I got is 4x (12db) higher (than the plot I just show above). If we place a ported sub behind the couch and sit close to the port location, it is like we emphasize the port output. So let us look at what-if in that situation. Let us say the net effect is as if the port output has been amplified by 6db, only modest gain. Let us look at the new FR and impulse response again. In reality because the distance between woofer and port, when we use particle velocity to convert to kinetic energy, you get even higher effectiveness because the differential nature of the force (when the woofer output and vented output is out of phase below port tuning frequency), a common technique in mechanical world. In the impulse response, the initial attack strength is the same, but the ringing swing now is stronger.
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post #35658 of 41367 Old 10-17-2018, 11:09 AM
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^^ Well written information on your last two posts there, Brian. Make sense to me. @Rythmik and @Mark Seaton are my two teachers here on avs 👍👍
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post #35659 of 41367 Old 10-17-2018, 03:17 PM
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One thing that does not get to mention that often around this part of avs is how the subs sound at low level listen? I am listening to some background music at -40MV while working and my FV15hps pair again puts a big smile on my face. They don’t draw attention to themselves but just sound soooooooo sweet/tight at such low level listening.
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post #35660 of 41367 Old 10-17-2018, 03:44 PM
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Originally Posted by Rythmik View Post
The FR of a ported sub is the sum of that from woofer and the port and they are not always in phase. Here I attached 4 plots. First is FR plots of all 3: port, woofer, and sum. Next is the impulse response of all 3. The magenta is the port output and the yellow is the sum. The zero line is 3 division from the bottom (or the trailing response). As you can see woofer and port are not always in phase. This is not a surprise because below tuning frequency, the port and woofer are out of phase. For instance, at the end of second division, the port and woofer are out of phase and the sum has a zero-crossing 1/4 from the end of 2nd division. In fact, a good half second division has woofer and port out of phase. This happens again at the end of 3rd division into 4th divison.

As I already explained before if I stick a near-field mic to a 3" port on a 12" ported sub, the measurement I got is 4x (12db) higher (than the plot I just show above). If we place a ported sub behind the couch and sit close to the port location, it is like we emphasize the port output. So let us look at what-if in that situation. Let us say the net effect is as if the port output has been amplified by 6db, only modest gain. Let us look at the new FR and impulse response again. In reality because the distance between woofer and port, when we use particle velocity to convert to kinetic energy, you get even higher effectiveness because the differential nature of the force (when the woofer output and vented output is out of phase below port tuning frequency), a common technique in mechanical world. In the impulse response, the initial attack strength is the same, but the ringing swing now is stronger.
This is great stuff @Rythmik ! Thanks for taking the time to do this. Let me put what you said into context of TR and Sound Intensity:

  • Placing the port close to the couch emphasizes the SPL in front of the port (near the back of the couch). In your what-if example, it is a 6db increase. However, there would be no net increase in SPL further away from the port (beyond the couch for example), and would look like your first example.
  • At the point when the woofer output and the vented output is perfectly out of phase, particle velocity (PVL) is at its highest, thereby increasing Sound Intensity (SIL) because SIL = SPL * PVL. This is something I've stated in the past that out of phase conditions increase PVL and resulting in increased SIL.
  • An increase in Sound Intensity equates to more vibration to the couch, or what we are referring as TR (Tactile Response).

Extrapolating further...

  • Sealed subs don't have these out of phase conditions like ported subs because it is just a driver and no port.
  • Placing a sealed sub in the same position of the example above, you'd notice a net gain in SPL relative to further away, but you would not see any increase in PVL because there is nothing fighting the phase. No net increase in PVL, no net increase in SIL, no net increase in TR

Conclusion:

This is why ported subs have more TR than sealed in the nearfield: increased PVL of the ported sub as it approaches the tune caused by out of phase conditions of the driver and port.

Increased PVL equates to increase SIL, resulting in more TR.

Sound about right? Others folks... feel free to weigh in.

-Dom
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post #35661 of 41367 Old 10-17-2018, 05:00 PM
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has rythmik ever considered titanium...I love my fujitsu ten eclipse titanium subs in my competition car....fujitsu ten eclipse uses aluminum for low cost subs and titanium for higher models...at least they used to.

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post #35662 of 41367 Old 10-17-2018, 05:06 PM
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has rythmik ever considered titanium...I love my fujitsu ten eclipse titanium subs in my competition car....fujitsu ten eclipse uses aluminum for low cost subs and titanium for higher models...at least they used to.
Due to recent China environmental regulations, the way our supplier used to make the silver cones coating it won't be possible anymore so the new method, which complies with the new environmental standards, will look exactly like titanium finish.

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post #35663 of 41367 Old 10-17-2018, 05:08 PM
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Originally Posted by dominguez1 View Post

Conclusion:

This is why ported subs have more TR than sealed in the nearfield: increased PVL of the ported sub as it approaches the tune caused by out of phase conditions of the driver and port.

Increased PVL equates to increase SIL, resulting in more TR.

Sound about right? Others folks... feel free to weigh in.
-Dom
Make sense to me.
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post #35664 of 41367 Old 10-17-2018, 11:49 PM
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Purchased a FV25HP today...

Will a Blue Yeti mic work for REW? I know nothing about REW but figured I best jump in head first if I want to utilize this thing proper.




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post #35665 of 41367 Old 10-18-2018, 12:35 AM
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Purchased a FV25HP today...

Will a Blue Yeti mic work for REW? I know nothing about REW but figured I best jump in head first if I want to utilize this thing proper.
Never heard of that mic, but it's possible. Most will recommend the UMIK-1 because it has built-in compatibility with REW. You can also get it from Cross Spectrum Labs if you want it calibrated, which improves precision below 20Hz and at the very high frequencies.

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post #35666 of 41367 Old 10-18-2018, 12:38 AM
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Never heard of that mic, but it's possible. Most will recommend the UMIK-1 because it has built-in compatibility with REW. You can also get it from Cross Spectrum Labs if you want it calibrated, which improves precision below 20Hz and at the very high frequencies.
Thanks man and yeah will look into the UMIK as well and that is what I have been seeing recommended as well.

The Blue mic is a pretty cool little microphone. - https://www.bluedesigns.com/products/yeti/ A lot of people use it for home recording and podcasts, but probably no for calibrating their subwoofers.

Just wanted to see if I'd be able to use it but you're probably right I should go w/ the pro UMIK mic if I want to start this off on the right foot.
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post #35667 of 41367 Old 10-18-2018, 09:12 AM
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The Yeti, like most recording mics, is not designed for flat response. It has an upper midrange peak and starts rolling off around 100 Hz (look at the polar plots, not just the ADC specs). So I would not use it for measurements unless you can provide a compensatory curve (do they provide that)?

The UMIK-1 is not a "pro" measurement mic IME/IMO but does a durn good job for most of us and is way easier to use (and much cheaper) than my Earthworks M30 for a fraction of the cost. As in, 99.99% of the time I am measuring a system, mine or somebody else's, I use the UMIK-1. I bought the CSL version to get better cal data (miniDSP has since improved their own cal procedure, not sure worth the extra $$$ unless you are exceptionally anal/picky) and the FR curves practically overlie compared to my M30.

So, short answer, yes get the UMIK-1 and be happy. Save the Yeti for recording and such.

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post #35668 of 41367 Old 10-18-2018, 10:09 AM
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Hey guys if you’re on Facebook, we’ve got a Rythmik Audio Subwoofer Owners Facebook group going! You’re welcome to join and share discuss your Rythmik pics and experience! It’s a fan made group with no affiliation to Rythmik Audio staff.

https://m.facebook.com/groups/257327308243597



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post #35669 of 41367 Old 10-18-2018, 10:34 AM
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Hey guys if you’re on Facebook, we’ve got a Rythmik Audio Subwoofer Owners Facebook group going! You’re welcome to join and share discuss your Rythmik pics and experience! It’s a fan made group with no affiliation to Rythmik Audio staff.

https://m.facebook.com/groups/257327308243597
Thanks for the link. I just went to the Facebook Rythmik group home page and requested permission to join.

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post #35670 of 41367 Old 10-18-2018, 10:35 AM
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Thanks for the link. I just went to the Facebook Rythmik group home page and requested permission to join.


You’re in, thanks.


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