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Thread: Alternative to Ryhmik

  1. #51
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    Default Re: Alternative to Ryhmik

    Hi Brian, got any pictures of the F18HP? And how much more output will it have compared to the F15HP?
    Last edited by mikesiskav; 12-10-2016 at 01:17 PM.

  2. #52
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    Default Re: Alternative to Ryhmik

    Quote Originally Posted by N Boros View Post
    Thank you for the detailed explanation. This helps a lot. Okay, so the high damping setting on your subs are going to be the most accurate in terms of phase. The sealed subs can be more accurate than the ported subs in this regard. What does the more accurate phase setting give you in terms of sound quality? Are you able to get more detail out of the same piece of music? Does it allow a more accurate location of where the bass is supposed to be located in the room (I have no idea, I'm just thinking about how phase is important in your main speakers in being able to locate sounds in three dimensional space, sometimes even behind you. But, with a subwoofer the signal is in mono so I don't think that this makes sense)?
    Phase and ring are related. You cannot get a system with high phase shift and yet give you no ringing in time domain. I understand most people treat some of the characteristics as if they have total degree of freedom. For instance, one thing I mentioned about ported sub is it has 4th order roll off. Most will think it is no big deal, I can live with that. But what i have not told you is 4th order has 2 Q values because a 4th order system can be thought of cascade of two 2nd order system with each 2nd order has a corner frequency F and a Q value. In other words, we have F1,F2,Q1,and Q2. Most will think he has complete freedom of picking F1, F2, Q1, and Q2. Unfortunately, it is not the case. So in reality, when some DIY picks a driver A and puts in a ported box B, most often he will get one high Q value and one low Q value. He cannot get low Q values for both both Q1 and Q2. The most commonly Q value combination is something like Q1=1.1 and Q2=0.6, or Q1=1.2 and Q2=0.5. Now you see the trend? If you try to reduce one Q, then the other Q pops up or if you want to make F1=15hz and keep Q1 and Q2 to the values you want, then F2 becomes 25hz. It is a constant game of seesaw.
    [EDIT]

    Another way to look at this problem is we compare sealed subs with ported subs. What is added to the system when we go from a sealed sub to a ported sub? The only thing we add is the port tuning frequnecy. That is, we add only one extra degree of freedom and yet we have two new variables F2, Q2 introduced in the system. That is why it is so difficult to controll all F1/Q1/F2/Q2 values exactly what we want them.


    Now if someone in college say I have access to symbolic math equation solver that I can solve this problem exactly. What he wil find is in order to get both Q values to be at 0.6 or lower, the enclosure may need to be so big or the driver needs to be so compliant that it becomes impractical. When we have one high Q and one low Q in your system, the ringing at the time domain is mainly determined by the high Q characteristics. That is why it is not a fair comparison for sealed and ported subs. Josh and other has tried to EQ a ported sub to a sealed sub in order to do subjective evaluation. Once you understand the big picture, you don't even bother to do that.
    Last edited by RythmikAudio; 12-12-2016 at 10:45 AM.

  3. #53
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    Default Re: Alternative to Ryhmik

    Quote Originally Posted by RythmikAudio View Post
    Phase and ring are related. You cannot get a system with high phase shift and yet give you no ringing in time domain. I understand most people treat some of the characteristics as if they have total degree of freedom. For instance, one thing I mentioned about ported sub is it has 4th order roll off. Most will think it is no big deal, I can live with that. But what i have not told you is 4th order has 2 Q values because a 4th order system can be thought of cascade of two 2nd order system with each 2nd order has a corner frequency F and a Q value. In other words, we have F1,F2,Q1,and Q2. Most will think he has complete freedom of picking F1, F2, Q1, and Q2. Unfortunately, it is not the case. So in reality, when some DIY picks a driver A and puts in a ported box B, most often he will get one high Q value and one low Q value. He cannot get low Q values for both both Q1 and Q2. The most commonly Q value combination is something like Q1=1.1 and Q2=0.6, or Q1=1.2 and Q2=0.5. Now you see the trend? If you try to reduce one Q, then the other Q pops up or if you want to make F1=15hz and keep Q1 and Q2 to the values you want, then F2 becomes 25hz. It is a constant game of seesaw.
    [EDIT]

    Another way to look at this problem is we compare sealed subs with ported subs. What is added to the system when we go from a sealed sub to a ported sub? The only thing we add is the port tuning frequnecy. That is, we add only one extra degree of freedom and yet we have two new variables F2, Q2 introduced in the system. That is why it is so difficult to controll all F1/Q1/F2/Q2 values exactly what we want them.


    Now if someone in college say I have access to symbolic math equation solver that I can solve this problem exactly. What he wil find is in order to get both Q values to be at 0.6 or lower, the enclosure may need to be so big or the driver needs to be so compliant that it becomes impractical. When we have one high Q and one low Q in your system, the ringing at the time domain is mainly determined by the high Q characteristics. That is why it is not a fair comparison for sealed and ported subs. Josh and other has tried to EQ a ported sub to a sealed sub in order to do subjective evaluation. Once you understand the big picture, you don't even bother to do that.
    I always feel dumber after reading one of Brian's posts, but sure makes me glad I'm a Rythmik owner

  4. #54
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    Default Re: Alternative to Ryhmik

    Quote Originally Posted by RythmikAudio View Post
    Phase and ring are related. You cannot get a system with high phase shift and yet give you no ringing in time domain. I understand most people treat some of the characteristics as if they have total degree of freedom. For instance, one thing I mentioned about ported sub is it has 4th order roll off. Most will think it is no big deal, I can live with that. But what i have not told you is 4th order has 2 Q values because a 4th order system can be thought of cascade of two 2nd order system with each 2nd order has a corner frequency F and a Q value. In other words, we have F1,F2,Q1,and Q2. Most will think he has complete freedom of picking F1, F2, Q1, and Q2. Unfortunately, it is not the case. So in reality, when some DIY picks a driver A and puts in a ported box B, most often he will get one high Q value and one low Q value. He cannot get low Q values for both both Q1 and Q2. The most commonly Q value combination is something like Q1=1.1 and Q2=0.6, or Q1=1.2 and Q2=0.5. Now you see the trend? If you try to reduce one Q, then the other Q pops up or if you want to make F1=15hz and keep Q1 and Q2 to the values you want, then F2 becomes 25hz. It is a constant game of seesaw.
    [EDIT]

    Another way to look at this problem is we compare sealed subs with ported subs. What is added to the system when we go from a sealed sub to a ported sub? The only thing we add is the port tuning frequnecy. That is, we add only one extra degree of freedom and yet we have two new variables F2, Q2 introduced in the system. That is why it is so difficult to controll all F1/Q1/F2/Q2 values exactly what we want them.


    Now if someone in college say I have access to symbolic math equation solver that I can solve this problem exactly. What he wil find is in order to get both Q values to be at 0.6 or lower, the enclosure may need to be so big or the driver needs to be so compliant that it becomes impractical. When we have one high Q and one low Q in your system, the ringing at the time domain is mainly determined by the high Q characteristics. That is why it is not a fair comparison for sealed and ported subs. Josh and other has tried to EQ a ported sub to a sealed sub in order to do subjective evaluation. Once you understand the big picture, you don't even bother to do that.
    Thank you for the explanation. I wasn't aware. This helps a lot!

    I have one more followup question. All things being equal, the sealed designs will always be more accurate in terms of minimizing ringing. So the sealed subwoofers will best match my Sierra 2 speakers, which have exceptional transient response. I like the accurate sound of those speakers 98% of the time (sometimes that extra detail is too much on certain passages).


    1) So if I am after the most accurate in terms of a matching subwoofer to these speaker, is a sealed subwoofer always going to be the best choice in my situation? My primary use is for home theater and I have a dedicated theater room that is about 1660 cubic feet and sealed.

    2) If so, is it just a matter of choosing the right sized sealed subwoofer that can give me the maximum clean output I would want?

    For example, I think the loudest I would ever listen to a movie would be at reference volume, which can demand up to 115 dB peaks in the LFE channel. So the F12 will not be able to cleanly hit those levels, even in this smaller room with 2 or 4 of them. Multiple F15HPs would likely be able to do this though. Now I could go with multiple FVX15s and use them with one port plugged to probably get similar output capabilities and similar transient accuracy, but the F15HPs will technically still have a little better transient response. We already start to see the need for a ported subwoofer. I can get the same output for a bit cheaper, if I am okay with the extra ringing. But, if I had a larger room and still wanted to hit 115 dB peaks, then it gets even more difficult try to stay with a sealed subwoofer in my application. The reason everyone can't choose a sealed sub to give the most accuracy is because some will have larger rooms and may want to listen at reference volume and a sealed subwoofer will just be too big and too expensive to use, when a more efficient ported subwoofer can be made to give the output needed, with the tradeoff of not quite as accurate transient response.

    3) Is this a reasonable way to decide when to go with ported over sealed, if you want to maintain the most accurate transient response?
    Last edited by N Boros; 12-14-2016 at 10:42 AM.

  5. #55
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    Default Re: Alternative to Ryhmik

    I was reading through this thread today; too bad it didn't keep going to provide the answers to the above post.

    Greg

  6. #56
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    Default Re: Alternative to Ryhmik

    Quote Originally Posted by ggarner149 View Post
    I was reading through this thread today; too bad it didn't keep going to provide the answers to the above post.

    Greg
    Since making the last post a little over a year ago now, I have learned quite a bit more about subwoofers and choosing the appropriate size for a room. Here are a collection of those thoughts, in case nobody else comes to add to the conversation.

    First of all, in a small room (any room that any of us have at home) full reference volume of 85 dB on average and 115 dB peaks in the LFE is not something that I or most any people want to listen at. Over at AVS forum there are a small group of people that talk about regularly listening to movie soundtracks at this level, or even above that level. (Consistently listening above this level regularly will cause permanent hearing damage slowly over time). But, really if you get an action Blu-Ray movie with an over the top soundtrack and adjust the volume dial, where is it usually set, where will you find it comfortable for the entire movie? If your receiver came with room EQ like Audyssey, then it will tell you where the volume is at with respect to reference volume, where it was mastered. If you don't have a relative volume setting on your receiver that was EQed in this way, you can just use a SPL meter to get a rough idea of how loud you like to listen. Most Blu-Rays for the home are mixed at 75 dB on average with as much as 105 dB peaks in the LFE. Typically I will listen somewhere between -20 dB and -15 dB, for such movies. I did nudge my subwoofer trim level up a bit after I ran Audyssey, maybe by 5 dB. The room EQ could be boosting things, maybe as much as say 5 dB. Let's say that if I really get crazy and crank things up when I have guests, then maybe I nudge things up by another 5 dB. So the absolute loudest that the LFE would need to be in my room would be about 75 dB - 15 dB + 5 dB + 5 dB + 5 dB = 75 dB on average with 105 dB peaks. This is a very safe estimate.

    Before when I was thinking that I want subwoofers to be capable of safely playing at full reference volume and as much as 115 dB peaks, this was simply because when I go to a movie theater to watch a movie, that is the level that most movies play at, or maybe slightly louder as many are mixed hot and I sit 1/3 of the way into the room from the screen for a more immersive viewing experience. At home this is uncomfortably loud. So how much subwoofer do I need? Well I can go over to data-bass.com, where Josh Ricci measured the new Rythmik subwoofers and pick out the one that will give me clean 105 dB peaks.

    http://data-bass.com/data?page=system&id=145&mset=171

    Just look under the "Static Graphs" tabs of the measurements and find the "In Room" CEA 2010 bursts. I find that for the F18 the subwoofer struggles most at 16 Hz with 103 dB output levels. For all other frequencies in the table, the subwoofer can put out either a little bit more, or a massive amount more. I want to make sure that I can hit 105 dB peaks and that it is clean (quite a bit less than 20% THD). Well I plan to get two subwoofers, so I can get about another 3 dB from the second F18. This gives me the 105 dB peaks. The distortion is a little higher at 16 Hz than I would like with 3rd order distortion being the main contributor. This would show up as around 48 Hz, which we can hear. However, Josh's room is a 3500 cubic foot room, with at least one hallway open to other parts of the house. So, I would probably get a little bit of room gain down low to where the distortion at 16 Hz, wouldn't be quite that high at 16 Hz and like I already mentioned I would rarely listen where peaks would be that loud. I would typically listen at least 5 dB less. So in my case, a pair of F18's can play anything that I can throw at it, within the levels that I would normally listen, with very low distortion.

    If I wanted to save some money, I could just shoot for getting two sealed Rythmiks that can hit 105 dB peaks cleanly at 20 Hz and then have the sub roll off below 20 Hz. Looking at Rythmik's chart ( http://www.rythmikaudio.com/ ) I could probably step all the way down to an F12, since a pair of F18s could put out about 111 dB at 20 Hz, cleanly. When we step down in driver size, the distortion will likely rise. So maybe I could step down to a pair of L22s or F15HPs would probably be safe, or even down to an F12 is probably even okay, but it might have high distortion at 20 Hz with a 105 dB peak. I guess I am a little picky though. I would prefer that the speakers and subwoofer are just reproducing the signal as faithfully as possible. So if there are some rare sounds below 20 Hz, which I know that we can't hear, only feel, I would like the subwoofer to reproduce it without adding distortion up in the audible band with 3rd or 4th order harmonics.

    Since I have a room smaller than Josh's room and I don't listen to movie soundtracks at really high levels, I have the flexibility of going with a sealed subwoofer. If my room were larger, or I listened at louder playback levels, or I just wanted to be the same output (at most frequencies) for less money, then I could just get ported Rythmik with a smaller driver. There are downsides here going with a ported model, in terms of having a larger subwoofer cabinet and transient response that isn't quite as good as a sealed Rythmik. But, since I have a smaller room and don't listen too loud, I am planning to go for a sealed Rythmik because I don't mind spending a little extra money to get a little bit better transient response. I remember one forum member within the past year describing the difference between the ported and sealed Rythmiks like this: high damping on the ported model is like mid damping on the sealed model, mid damping on the ported model is like low damping on the sealed model. So how are the ported and sealed Rythmik's different with respect to transient response? The sealed model has one more notch to go for faster transient response and the ported model has one more notch to for a more fuller sound. I am seeking the most accurate, so the sealed on high damping is what I want.

    I have Sierra 2s for my front speakers. So wouldn't a pair of F18's be ridiculous because of the mismatch in output levels? Well the F18's can likely cleanly get to 105 dB peaks in my room. The Sierra 2s can play 95 dB sustained in room without showing any compression, as measured by a forum member here:

    http://forum.ascendacoustics.com/sho...nts-in-my-room

    I only need them to play 95 dB peaks cleanly. So I think that they do actually match well. And again, the only reason for the F18s over say the F15HPs or L22s would be so that I can play below 20 Hz content that some movies call for.
    Last edited by N Boros; 02-17-2018 at 03:31 PM.

  7. #57
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    Default Re: Alternative to Ryhmik

    Hi, Thanks for chiming back in with your experience. Your listening preferences match my own and I like your logic and analysis. My biggest issue is my room size. It is a 3,000 cu ft room but opens to another ~7,000 cu ft. There are some walls in each room, but it still presents a big space for bass. My preference though, like your own, is for sealed subs. I'm even thinking the new E15HP2 (pair, eventually) is an interesting option as it is almost as loud at 20 hz as the F18. But even Rythmik hasn't published it's performance curves yet and I haven't seen anyone comment on them at AVS or here.

    For a single-sub placement, is there anything magic about placing it in the front of the room? the FV18 installation guide says one good placement is in between the front speakers. I prefer mine behind me as it is less in the way, but also a few feet closer to my ears.
    Last edited by ggarner149; 02-19-2018 at 12:34 PM. Reason: spelling

  8. #58
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    Default Re: Alternative to Ryhmik

    Maybe I should expand a little on my comments and add some context. Currently I have an old Outlaw LFM-1 subwoofer in the corner of a finished basement that is completely open concept. So the total space might be 10,000 to 12,000 cubic feet. My priority is home theater, though I do a slight bit of listening to concert Blu-rays and music. Anyways, if I were to go with a subwoofer in this particular space I would not at all be looking for a sealed subwoofer. The ever so slight improvement to transient response would in no way make up for the fact that I have a huge space and can get output much more economically with a ported subwoofer. Currently I'm not happy with the bass, because there is very little feeling to the bass, even though I hear things mostly fine. I can hear that my Sierra 2s as mains have better transient response than my subwoofer and I have it placed and integrated well.

    Because of this I plan to put up a couple of walls to get down to about a sealed, rectangular 2,000 cubic foot room. What is nice here is that as I mentioned above, even a small sealed subwoofer basically gives me all of the output down to 20 Hz that I need and should be pretty much clean even down at 20Hz. However, there are some movie soundtracks that dip below 20Hz, so I want to make sure that the subwoofer can also produce those well and with low distortion, which is why I'm leaning towards the F18s. The sealed rectangular room allows me to know, because of Todd Welti's research at Harman, where the optimal placement of two subs will be to minimize the standing waves (and as a result each seat will sound very similar). The smaller sealed room also makes the use of bookshelf speakers for mains and smaller speakers in other areas also fine. Things are predictable and easier to plan, even into the room treatments to help fix some of the room anomalies. Best of all, the smaller sealed room allows me to pressurize the room with bass. This will give me the bass that I can feel, that is currently lacking. If I want to pressurize a 10,000 to 12,000 cubic foot space, then I need subs with massive output capabilities. A single FV25HP might not be enough. So do I want to spend large sums of money on subwoofers to try to pressurize the whole basement, and have my wife and kids probably upset with me , or just put up a couple of walls to come at the problem from a different angle?

    If my room were much larger than 2000 cubic feet, or I liked to listen a bit louder, then sealed subwoofers would no longer be feasible for me. I would be looking at bigger ported models. If music were a priority and I weren't quite as concerned about the tactile feel of the bass, then maybe smaller sealed subwoofers would be fine for me in a larger space though.

    For the placement of a single subwoofer, typically the best thing to do is the "subwoofer crawl". With this technique you put subwoofer in your seat that you will listen at. You can only typically get one good seat for the bass with one subwoofer. To find the best location for the subwoofer you crawl around to the different locations for the subwoofer while listening to sweeps. Make a sweep for about 10 seconds from 100Hz down to 20 Hz here. Unplug or turn off your other speakers. Once you find the location where the sweep sounds either the most even, or there aren't any nulls or dips, then you have found a good location for the subwoofer. Take the subwoofer out of your seat and put it in that spot. The bass that you heard in the location should be very similar to what you have now in your seat. If the bass doesn't have any nulls yet it doesn't sound even, you should be able to run a room EQ like Audyssey, which will be able to bring down any peaks and make the bass even from 20 to 80Hz.
    Last edited by N Boros; 02-21-2018 at 12:29 PM.

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