ttocs
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Post by ttocs on Dec 20, 2020 12:40:34 GMT -5
ttocs, hsamwel .... I have a little different spin on the idea while being in full agreement on the principle that the LFE channel and bass from small speakers (yes, BM!) are best served by different solutions. B - I believe LFE requires a solution biased toward much lower frequencies (generally <40Hz, even though LFE spec goes up to 120Hz), needing higher peak output to create the "E" in LFE, and generally not containing the nuances of music or dialogue. C - I believe BM requires a solution biased toward frequencies between 40Hz and 200Hz, does not need the same peak output as LFE, and has music and dialogue content that benefits from the more articulate reproduction provided by full range speakers. i.e. excellent full range speakers like ttocs' Martin Logans or my Magnepans. p.s. I really think this is a great topic and I honestly have never seen it discussed anywhere else! Kind of amazing. I agree with all of the above. Marc, if what I'm hearing as better clarity is not due to less distortion, then what would you suggest is the reason for the much clearer audio coming from the Center Channel specifically? All 3 movies I watched last weekend were noticeably more intelligible with respect to Center Channel audio. |
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Post by marcl on Dec 20, 2020 13:22:49 GMT -5
ttocs, hsamwel .... I have a little different spin on the idea while being in full agreement on the principle that the LFE channel and bass from small speakers (yes, BM!) are best served by different solutions. B - I believe LFE requires a solution biased toward much lower frequencies (generally <40Hz, even though LFE spec goes up to 120Hz), needing higher peak output to create the "E" in LFE, and generally not containing the nuances of music or dialogue. C - I believe BM requires a solution biased toward frequencies between 40Hz and 200Hz, does not need the same peak output as LFE, and has music and dialogue content that benefits from the more articulate reproduction provided by full range speakers. i.e. excellent full range speakers like ttocs' Martin Logans or my Magnepans. p.s. I really think this is a great topic and I honestly have never seen it discussed anywhere else! Kind of amazing. I agree with all of the above. Marc, if what I'm hearing as better clarity is not due to less distortion, then what would you suggest is the reason for the much clearer audio coming from the Center Channel specifically? All 3 movies I watched last weekend were noticeably more intelligible with respect to Center Channel audio. Oh I don't doubt there's better clarity and it's related to distortion or transient response or other things. Maybe I misunderstood, but I'm saying the sub reproduction of LFE explosions does not cause it to distort the reproduction of a bass fiddle. The bass fiddle is better rendered by the ML while the explosions are better rendered by the sub. That's the reason to separate them. I'll admit I may be out of sync with the current system, but it made perfect sense that you'd get better center channel low end from your MLs than your subs. If you now are using a dedicated sub (separate and distinct from your LFE subs) for center channel bass, and center bass is not going to the MLs .... does that sound better than when you had center channel bass going to the MLs? If that's the case, then it means this center channel sub performs better in the bass than the MLs do? |
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ttocs
Global Moderator
I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
Posts: 8,171
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Post by ttocs on Dec 20, 2020 18:39:29 GMT -5
Ok, so I ordered a miniDSP for the BM Group (two stacks of 2 subs each, total of 4 subs working together), that'll give the most versatility and hopefully help with this null. I'm also going to make attempts at experimenting with DIY bass traps using the 4 bales of mineral wool I've got on hand. I dedicated today to playing with doors, absorption panels, and subwoofer placement. Of the three, placement and doors had measurable impact for the big null between 60-80Hz. Doors There are 5 doors in a hallway left of the room, and one opening to basement stairs in the back of the room. Closing all the doors and the opening to the basement was not the best. Leaving the basement stairs open and one bathroom door open resulted in the best overall improvement vs all open, and that includes closing off the hallway opening. Closing off what is now open causes more problems. Absorption The panels I have on hand which are 30"x48" ranged from doing relatively nothing to being destructive. I tried single and multiple corners, 4' and 8' tall, side walls, front and back walls, and they just aren't up to the task. After dinner I might try using some new bales of mineral wool in the corners, but I'm kinda pooped right now. Placement This is by far the easiest to get really noticeable results from. By moving the Right SOS (Stack Of Subs) farther and farther from the right wall caused the null to become smaller and smaller in width (Hz), and changing the depth (dB) for the better - albeit in altering the lumps between 5-10dB down. The issue with the improving placement as the SOS is moved left is that it's now becoming a problem for room layout. I'm gonna see this through however, just to see what happens. I don't mind moving the tv a little left, but it really can't move more than 4-5". Think of the Left Speaker, TV, and Right Speaker as an accordion, I can move the Right Speaker/SOS left 9" and only need to move the tv half that to keep it centered. But this is working against two things, one being the dining area, which can be encroached upon by a few inches, the other being the tv mount WHICH IS NOT MOVING! So I think there's about 4-5 inches of movement for the tv before it runs out of runway, could be wrong by a little, but that's pretty close. So it's really the TV that is the limiting factor in bass-happiness. Here's a plot showing the starting point with no Dirac, and where it's at now after Dirac and moving the Right SOS. edit: Annotated incorrectly in the first image, now corrected. Added the comparison of best before and after Dirac. Volume levels were not changed between measurements, the Post Dirac is a lower level. Dirac 3.0.11. I got much better results with 3.0.5 in the past.   Each stack works just fine even without being able to use the built-in XO in each sub due to using the LFE inputs on the subs which doesn't go through the XO. So for the dedicated augmented bass purpose for each Main speaker, they will be easy to tame, as previous quick tests have shown. The lowest common denominator with these four subs is when they all work together. Right now one stack is connected to the Left Sub Out, and the other is on the Right Sub Out. The important thing to keep in mind is the primary goal which is to augment the bass in two channel mode with no Dirac, and this requires that they be placed as close to the L&R speakers as possible. I'm forced to work backwards because I also want to use these for BM. So it's a back and forth sort of thing. Get each pair good, then make all four good, then make sure each pair still works good. The new miniDSP arrives tomorrow so Tuesday will be fun. I'm happy that I won't need to close off the hallway, or the basement stairs. I'd do it if it was a good improvement. So tonight quick and dirty bass traps. Tuesday night, miniDSP tuning. |
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Post by marcl on Dec 20, 2020 18:50:28 GMT -5
Corners are the best bet, but the mineral wool probably isn't dense enough to work on the frequencies that you need. Owens Corning 703 or the denser 705 4" or 6" thick will work better. Also helps to have the side facing into the room covered with heavy kraft paper or a thin sheet of plastic ... or get some of the FRK 705 and use it only for the outer layer. And they need to be away from the wall, not against it. So best way to do that is standing in the vertical corners or laid across the floor-wall corners or hanging across the ceiling-wall corners. I realize the last idea is not practical for experiments. But since they need to be away from the wall, maybe put them directly behind each sub stack. Edit: I went down the bass trap rabbit hole a few years ago, and it definitely made a difference ... albeit in small increments with diminishing returns. I estimate I have at least 50 pieces of 703 or 705, 2x4ft x2", stacked 4, 6 or 8 inches thick. There are six of them 6" thick across ceiling corners, 4" thick floor to ceiling two vertical corners, 8" thick 4ft high one vertical comer, and the front right corner is "super chunk" triangles of 705 completely filling the corner floor to ceiling. Then - since the TV is 4ft from the front and speakers are farther than that - I have four 2x4ft x8" thick pieces on edge on the floor 2ft high (just up to the height of the TV base) and extending out from the corners and front wall four feet. These last ones that are farthest from the wall made the biggest difference incrementally. All this to say ... it takes a LOT of DIY traps and I moved them around the room many times and measured each time. Incremental changes were at best 2db, and many times there was no effect at all ... especially on walls. Adding heavy kraft paper to the room-facing side improves performance a couple db on its own. Edit 2: A little more information on the effectiveness of bass traps for those who may be interested. The attached measurements represent snapshots over several years, starting with a system with no bass traps and one 10" sub, to adding a second 12" sub and 25+ bass traps, and then some further refinement with a miniDSP and other speaker positioning. Finally there's the result of Dirac calibration applied to a room where all other avenues of modal resonance remediation had been tried.  Glad to discuss here or in PM if anyone has any questions. |
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Post by hsamwel on Dec 23, 2020 7:34:27 GMT -5
1. Why would bass mangement+LFE mixed together create distortion? 2. How can one or two subs playing together for each channel play better than let’s say five together calibrated and placed att good positions? 3. What if you use all of the 7 subs for ONE mixed mono channel with a MiniDSP? And then let Dirac calibrate it as one? 1. LFE is solely for sound effects and low frequency sounds and rumbles. Dolby never intended the LFE audio track to be mixed with any other track. Every channel is supposed to be produced by a "Full Range Speaker. This is not the answer you seek, yet. In a movie with action taking place along with dialogue, the LFE track will be playing heavy, low, thunderous sounds - all of which are below 100Hz - while dialogue is going on. It's reasonable to keep these audio tracks separate so the LFE sounds don't interfere with sound that has more detail in the lower ranges. This can be assumed to be conjecture, until you try it. I separated the LFE into its own subwoofer group using the 3 subs I had at the time. This meant that the bass below the crossovers for all the Small speakers would now be produced by the Large Left/Right speakers with very capable woofers that operate very well up to their 300Hz crossover in the speaker itself. The Center Speaker was instantly clearer and more intelligible!!, and so were the Surrounds. So, my system, in my room, with my subwoofers, having the LFE go away from all the other speakers resulted in a substantial gain in clarity in all the Small speakers. So then I began raising the XO setting for the Center Speaker, which I have had complaint with in regards to the weak low end, and with each raising of the XO there was improvement. At the point where I decided to get more subwoofers, the XO setting was at 150Hz for the Center speaker. Now, I have a subwoofer waiting to be tested, just for the Center channel only. I'll get to that in a few days after working on other things first. 2. This is not really a question with enough clarity to answer with specifics because, in my mind, there are some nuances in what those one or two subs are setup to do. In my case, I have 4 subwoofers in 2 stacks of 2, next to the Left and Right Main speakers. They have two duties: To run as a group of 4 for Bass Management (sorry Keith, I will use BM as a designation for all bass below the XO for all Small speakers) for all Small speakers. And, to run as dedicated pairs for the Left and Right speakers BUT using the High Level Connection (HLC) and used as Augmented Bass for the L&R. My L&R speakers have bass controls for contouring the bass. One is for 75Hz and below, and the other is for Mid-Bass boost and cut. Between these two controls, and ARC, there is quite a lot of help in the bass region before enlisting Dirac for anything. In addition to the above, each subwoofer has some versatile controls plus ARC. The idea of Stack-Of-Subs (SOS) is something promulgated by Rel. I have always liked the idea, but could never find information or demonstrations proving the concept, just a lot of talk by Rel. I "wanted" more subs, so I decided to try this and test it out. I have not had the time do do this yet. I'm working on using the 4 subs for the BM Group. With the work that's been going on within my house, it's something that's been relegated to the little time I spent on it last weekend to get ready for a Movie Night! last Monday. And even though there really was very little time in getting the system up and running after a MAJOR rewiring, the movies we watched sounded the best so far! But, to answer one version of your question directly, they can't. But. Specific intended purpose for the subwoofers comes into play, so it's not so simple for everyone, specifically me. My primary purpose for having the SOS is for the HLC method for augmented bass for the Mains. The secondary usage is for BM. I'm working on each pair to be as good as they can be, and that is working out VERY well! But I also want the 4 subs to play well together, and for this I am getting close to getting another miniDSP. There's a huge dip I will be working on tomorrow, firstly with altering the placement of each SOS and its companion Left or Right speaker but placement options are limited, secondly with room treatment, thirdly by adding a couple doors to my room. I'm in no rush, just want to cover the bases with regard to the foundation of the learning involved. So it's a step by step process. 3. I will never go back to a combined LFE/BM system. I "am" amenable to using more miniDSP's for each multi-sub group so Dirac can calibrate each group as an individual. Again, it's a step by step process. I want to exhaust as much as I am willing and capable of before going on to the next idea. So in the end, the system may (probably) end up being 2 main subwoofer groups for 7 of the 8 subwoofers that are connected to the Center Sub Output for LFE, and Left Sub Output for BM. The HLC for each Left Pair and Right Pair of subs is relatively passive as it is setup to respond from the same speaker connection as the Left and Right speakers, and as such Dirac will calibrate the Left w/SOS and Right w/SOS as full range speakers. The Center Speaker and its Subwoofer will be controlled by a active XO, so the processor will not be involved and Dirac will calibrate as a full range speaker. I’m not questioning your findings.. Many times the quality of bass is due to having less capable subs than main speakers. Having $10000 front speakers and complaining that the bass is not as good from the $1000 subs is a little obvious to me. Especially above 50-60hz. This was not directed at your setup specifically. But moving bass to main speakers is not always such a good idea. Why? Well, for the same reasons you move your subs around to get good bass. The difference being that the fronts have their place and most often can’t be moved to a better place. So you get the bass you get from the place they stand, good or bad. Separating LFE and BM I can buy.. But having no less than 2 subs for each. Optimally 4 subs for each. That’s alot of subs. Probably why most make do with mixing LFE and BM. I agree with having a higher crossover for the center. When going below 60hz I have noticed it gets a little muddy. I usually don’t go lower than 70-80hz for a center. Dirac has helped with this though. I have a friend that has struggled with his center as well. He’s always had really large and expensive center speakers. Always set them to large due to them going down to 30-40hz.. Now he has them set at 80hz and no more trouble with intelligibility. Where the center is placed it’s often not good to have another ”sub”. Stacking subs is quite old. I remember Miller & Kriesel recommended this also way way back. Your setup is quite special like Marcl’s is. So general statements or rules probably don’t apply. Either way it’s interresting to read about your experiments. Thanks for sharing! |
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Post by foggy1956 on Dec 23, 2020 8:55:44 GMT -5
Ok, so I ordered a miniDSP for the BM Group (two stacks of 2 subs each, total of 4 subs working together), that'll give the most versatility and hopefully help with this null. I'm also going to make attempts at experimenting with DIY bass traps using the 4 bales of mineral wool I've got on hand. I dedicated today to playing with doors, absorption panels, and subwoofer placement. Of the three, placement and doors had measurable impact for the big null between 60-80Hz. Doors There are 5 doors in a hallway left of the room, and one opening to basement stairs in the back of the room. Closing all the doors and the opening to the basement was not the best. Leaving the basement stairs open and one bathroom door open resulted in the best overall improvement vs all open, and that includes closing off the hallway opening. Closing off what is now open causes more problems. Absorption The panels I have on hand which are 30"x48" ranged from doing relatively nothing to being destructive. I tried single and multiple corners, 4' and 8' tall, side walls, front and back walls, and they just aren't up to the task. After dinner I might try using some new bales of mineral wool in the corners, but I'm kinda pooped right now. Placement This is by far the easiest to get really noticeable results from. By moving the Right SOS (Stack Of Subs) farther and farther from the right wall caused the null to become smaller and smaller in width (Hz), and changing the depth (dB) for the better - albeit in altering the lumps between 5-10dB down. The issue with the improving placement as the SOS is moved left is that it's now becoming a problem for room layout. I'm gonna see this through however, just to see what happens. I don't mind moving the tv a little left, but it really can't move more than 4-5". Think of the Left Speaker, TV, and Right Speaker as an accordion, I can move the Right Speaker/SOS left 9" and only need to move the tv half that to keep it centered. But this is working against two things, one being the dining area, which can be encroached upon by a few inches, the other being the tv mount WHICH IS NOT MOVING! So I think there's about 4-5 inches of movement for the tv before it runs out of runway, could be wrong by a little, but that's pretty close. So it's really the TV that is the limiting factor in bass-happiness. Here's a plot showing the starting point with no Dirac, and where it's at now after Dirac and moving the Right SOS. edit: Annotated incorrectly in the first image, now corrected. Added the comparison of best before and after Dirac. Volume levels were not changed between measurements, the Post Dirac is a lower level. Dirac 3.0.11. I got much better results with 3.0.5 in the past. View Attachment View AttachmentEach stack works just fine even without being able to use the built-in XO in each sub due to using the LFE inputs on the subs which doesn't go through the XO. So for the dedicated augmented bass purpose for each Main speaker, they will be easy to tame, as previous quick tests have shown. The lowest common denominator with these four subs is when they all work together. Right now one stack is connected to the Left Sub Out, and the other is on the Right Sub Out. The important thing to keep in mind is the primary goal which is to augment the bass in two channel mode with no Dirac, and this requires that they be placed as close to the L&R speakers as possible. I'm forced to work backwards because I also want to use these for BM. So it's a back and forth sort of thing. Get each pair good, then make all four good, then make sure each pair still works good. The new miniDSP arrives tomorrow so Tuesday will be fun. I'm happy that I won't need to close off the hallway, or the basement stairs. I'd do it if it was a good improvement. So tonight quick and dirty bass traps. Tuesday night, miniDSP tuning. Curious, with the miniDSP do you build filters individually, combined, or both, prior to running DIRAC? |
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ttocs
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I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
Posts: 8,171
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Post by ttocs on Dec 23, 2020 11:54:39 GMT -5
I’m not questioning your findings.. Many times the quality of bass is due to having less capable subs than main speakers. Having $10000 front speakers and complaining that the bass is not as good from the $1000 subs is a little obvious to me. Especially above 50-60hz. This was not directed at your setup specifically. But moving bass to main speakers is not always such a good idea. Why? Well, for the same reasons you move your subs around to get good bass. The difference being that the fronts have their place and most often can’t be moved to a better place. So you get the bass you get from the place they stand, good or bad. Separating LFE and BM I can buy.. But having no less than 2 subs for each. Optimally 4 subs for each. That’s alot of subs. Probably why most make do with mixing LFE and BM. I agree with having a higher crossover for the center. When going below 60hz I have noticed it gets a little muddy. I usually don’t go lower than 70-80hz for a center. Dirac has helped with this though. I have a friend that has struggled with his center as well. He’s always had really large and expensive center speakers. Always set them to large due to them going down to 30-40hz.. Now he has them set at 80hz and no more trouble with intelligibility. Where the center is placed it’s often not good to have another ”sub”. Stacking subs is quite old. I remember Miller & Kriesel recommended this also way way back. Your setup is quite special like Marcl’s is. So general statements or rules probably don’t apply. Either way it’s interresting to read about your experiments. Thanks for sharing! I'm really enjoying the journey with this sub bass stuff. I've had lots of questions for years and could never get satisfactory answers. Now that I'm using myself as a lab rat it's leading from one query/result to another. Some of my comments about which speaker or sub does what are a moving target, but I present them as ideas to consider. My journey of moving the BM to the Mains resulted in improvement. Then separating a single channel for having a dedicated sub resulted in further improvement, etc. When you pair it all down, getting back to what Dolby specs for Surround and ATMOS seems to give the best result channel to channel, subwoofery notwithstanding, that's a separate issue. Dolby specs each channel to be full range except the .1 which is limited to 120Hz. How we get there is why there's so many directions we can take with regard to Large/Small speakers, and single/multiple subs for BM in addition to the single/multiple subs for the .1 channel, or, as you stated, combining the BM and .1 together in a particular single sub or multi-sub group. And your point about placement is valid if it's just for getting the best bass. But, my effort in placing the twin stacks is very specific to a primary purpose, with a secondary purpose close behind just because it can (BM that is). I'm trying new ideas, just because. I'm not only stacking subs, I'm also trying some arrangements normally experienced in live audio events, again, just because. Once I learn how to break the acoustics in my room, which I've done quite a bit this year, then I can hone in on the better arrangements. This stuff is such a "secret" for some reason. Probably the most critical frequency range is in the lower 3-5 octaves. This is where things can get very bloated, weak, one note, boomy, etc. But get this right and it's a cool experience! This is all good fun, and I love being able to share what happens, no matter if it's pass or fail. |
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ttocs
Global Moderator
I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
Posts: 8,171
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Post by ttocs on Dec 23, 2020 11:59:36 GMT -5
Curious, with the miniDSP do you build filters individually, combined, or both, prior to running DIRAC? I have yet to build any filters with the miniDSP, so don't know how yet. What I have done is play a little with PEQ in the miniDSP and got a good result with the LFE subwoofer group. I ended up not needing that after I moved the subs to where they are, but it was pretty easy to lower a big bump. But yes, I did the placement, then PEQ, then Dirac. |
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Post by foggy1956 on Dec 23, 2020 12:37:32 GMT -5
Curious, with the miniDSP do you build filters individually, combined, or both, prior to running DIRAC? I have yet to build any filters with the miniDSP, so don't know how yet. What I have done is play a little with PEQ in the miniDSP and got a good result with the LFE subwoofer group. I ended up not needing that after I moved the subs to where they are, but it was pretty easy to lower a big bump. But yes, I did the placement, then PEQ, then Dirac. But, do you PEQ the individual subs, the group, or both? |
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ttocs
Global Moderator
I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
Posts: 8,171
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Post by ttocs on Dec 23, 2020 13:02:36 GMT -5
I have yet to build any filters with the miniDSP, so don't know how yet. What I have done is play a little with PEQ in the miniDSP and got a good result with the LFE subwoofer group. I ended up not needing that after I moved the subs to where they are, but it was pretty easy to lower a big bump. But yes, I did the placement, then PEQ, then Dirac. But, do you PEQ the individual subs, the group, or both? When I used the PEQ it was for 1-sub in a 3-sub-group. I played with each one and found one that responded well to the issue. Also, the individual settings for each sub were quite different, including Gain, Inverted, Delay, and High Pass and/or Low Pass settings which mostly were Bypassed except as needed. |
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Post by hsamwel on Dec 23, 2020 18:00:49 GMT -5
I’m not questioning your findings.. Many times the quality of bass is due to having less capable subs than main speakers. Having $10000 front speakers and complaining that the bass is not as good from the $1000 subs is a little obvious to me. Especially above 50-60hz. This was not directed at your setup specifically. But moving bass to main speakers is not always such a good idea. Why? Well, for the same reasons you move your subs around to get good bass. The difference being that the fronts have their place and most often can’t be moved to a better place. So you get the bass you get from the place they stand, good or bad. Separating LFE and BM I can buy.. But having no less than 2 subs for each. Optimally 4 subs for each. That’s alot of subs. Probably why most make do with mixing LFE and BM. I agree with having a higher crossover for the center. When going below 60hz I have noticed it gets a little muddy. I usually don’t go lower than 70-80hz for a center. Dirac has helped with this though. I have a friend that has struggled with his center as well. He’s always had really large and expensive center speakers. Always set them to large due to them going down to 30-40hz.. Now he has them set at 80hz and no more trouble with intelligibility. Where the center is placed it’s often not good to have another ”sub”. Stacking subs is quite old. I remember Miller & Kriesel recommended this also way way back. Your setup is quite special like Marcl’s is. So general statements or rules probably don’t apply. Either way it’s interresting to read about your experiments. Thanks for sharing! I'm really enjoying the journey with this sub bass stuff. I've had lots of questions for years and could never get satisfactory answers. Now that I'm using myself as a lab rat it's leading from one query/result to another. Some of my comments about which speaker or sub does what are a moving target, but I present them as ideas to consider. My journey of moving the BM to the Mains resulted in improvement. Then separating a single channel for having a dedicated sub resulted in further improvement, etc. When you pair it all down, getting back to what Dolby specs for Surround and ATMOS seems to give the best result channel to channel, subwoofery notwithstanding, that's a separate issue. Dolby specs each channel to be full range except the .1 which is limited to 120Hz. How we get there is why there's so many directions we can take with regard to Large/Small speakers, and single/multiple subs for BM in addition to the single/multiple subs for the .1 channel, or, as you stated, combining the BM and .1 together in a particular single sub or multi-sub group. And your point about placement is valid if it's just for getting the best bass. But, my effort in placing the twin stacks is very specific to a primary purpose, with a secondary purpose close behind just because it can (BM that is). I'm trying new ideas, just because. I'm not only stacking subs, I'm also trying some arrangements normally experienced in live audio events, again, just because. Once I learn how to break the acoustics in my room, which I've done quite a bit this year, then I can hone in on the better arrangements. This stuff is such a "secret" for some reason. Probably the most critical frequency range is in the lower 3-5 octaves. This is where things can get very bloated, weak, one note, boomy, etc. But get this right and it's a cool experience! This is all good fun, and I love being able to share what happens, no matter if it's pass or fail. Note that Dolby specs for large 20-20k hz speakers is for cinemas. In home there was always ment to be bass mangement. There aren’t that many speakers for homes that play flat down to 20hz at reference levels. Also, it’s not realistic to have 5 or more full range speakers in homes. But if you have real full range front speakers and they give good response at their location then I can’t see why moving BM to them would harm. The bass above 50hz should feel faster, especially for music I guess. Dirac calibrates my fronts to about 22hz flat with Harman 4db. I could actually reconfigure my system to have large fronts and set my two subs to LFE with a serial connection (I have a XLR out on my subs). Then run Dirac again to see if I get the same improvements you’ve got.  |
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Post by hsamwel on Dec 23, 2020 19:22:13 GMT -5
ttocs, hsamwel .... I have a little different spin on the idea while being in full agreement on the principle that the LFE channel and bass from small speakers (yes, BM!) are best served by different solutions. A - I don't believe BM sounds better separated from LFE because the nature of the content causes interference and distortion between them when played through the same speakers. I believe BM sounds better separated from LFE only if the system reproducing the BM is fundamentally different and better suited to the task ... i.e. not just a separate set of subwoofers. B - I believe LFE requires a solution biased toward much lower frequencies (generally <40Hz, even though LFE spec goes up to 120Hz), needing higher peak output to create the "E" in LFE, and generally not containing the nuances of music or dialogue. C - I believe BM requires a solution biased toward frequencies between 40Hz and 200Hz, does not need the same peak output as LFE, and has music and dialogue content that benefits from the more articulate reproduction provided by full range speakers. i.e. excellent full range speakers like ttocs' Martin Logans or my Magnepans. D - As far as I have found in my research, the Harman paper on multiple subs provides the most rigorous mix of simulation and empirical data supporting two or four subs distributed, not with respect to L/R channels, but rather optimized to provide more uniform bass response across listening positions and reducing the magnitude of peaks and nulls ... in acoustically small rooms, in which we all live. REL doesn't provide much science behind their stack idea, though the stack idea does have legitimate origins in large scale sound reinforcement with lots of science describing several solutions ... very complicated physical and phase relationships as well as crossovers and levels. I just don't think the sound reinforcement use case translates to small room acoustics. They are never dealing with modal resonances. So ... again agreeing in principle, I like a solution that definitely sets LFE apart with its own speakers and amps. I believe BM is best served sent to full range L/R speakers, perhaps augmented with subs only <40Hz. This is how my system is set up now. p.s. I really think this is a great topic and I honestly have never seen it discussed anywhere else! Kind of amazing. Yes, even though LFE has most of its sound in the <60hz region it does have alot above it as well. It’s a myth that all the sound in explosions and such only happen in <40hz. I would say it’s important to have subs (with BM) from <80hz if you are playing at reference level or near it and want to have bass played as hard, loud and clean as it’s meant to. Most front speakers, even though in some cases reach 20-25hz, won’t get the SPL as cleanly as a sub does at reference levels. Especially below 40-50hz. So using fronts for BM can work but it depends on how loud you play and how they measure at their location. It’s great as you do with adding subs <40hz for BM. If the fronts measure great and can cope with the SPL 40-80hz it should all be good. You get the best from both sides, speed and depth. I agree with bass from BM (all channels) probably isn’t focused on <40hz. But this depends on production. There are 5.0 sources (however rare) and some may put heavy deep bass in all channels. Then you have the crossover and slope to think about. You need to have some margin. If the fronts play good to 50hz, 50hz is not a good crossover point. Maybe 80hz is better? Not directly related but.. I read an article some years back about subs and bass. In it the writer dismissed ”music” subs or alike. He simply stated, if you can’t get bass to sound good with music and movies alike then you haven’t got a good enough sub compared to your fronts. He also wrote that most people will pay huge amounts for front speakers and skimp out on the sub(s). According to him a sub should generally cost about the same as the front speakers to play equally good. I lost the article I’m sorry to say, so I have no link. But if I remember correctly it was some ”heavy weight” from the industry at the time. I can safely say I have skimped out!  |
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ttocs
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Post by ttocs on Dec 23, 2020 20:56:51 GMT -5
Note that Dolby specs for large 20-20k hz speakers is for cinemas. In home there was always ment to be bass mangement. There aren’t that many speakers for homes that play flat down to 20hz at reference levels. Also, it’s not realistic to have 5 or more full range speakers in homes. Actually, Dolby is pretty easy going on the specs for speakers. Below are some quotes direct from the ATMOS guide. “DolbyAtmos® Specifications”Screen Speakers: LCR “2.3 Frequency Range:40Hz to 16kHz,+3/–6dB”Subwoofer LFE @+10dB “3.2 Frequency Response: 31.5–120 Hz, ±3 dB”Surrounds: Includes Sides, Rears, Tops. “4.6 Surround Sound Frequency Response:40Hz to 16kHz,+3/–6dB”Surround Subwoofers if using BM @+0dB “5.2 SurroundSubwooferFrequencyResponse:40–120Hz,+3/–6dB
Each surround subwoofer (if bass management is used) must have a frequency response of 40–120 Hz, +3/–6 dB.”But if you have real full range front speakers and they give good response at their location then I can’t see why moving BM to them would harm. The bass above 50hz should feel faster, especially for music I guess. When I had BM going to my mains I liked the sound much better than when BM was mixed with the LFE in the 3 subwoofers. Now that I've got BM going to a dual purpose subwoofer group the BM didn't improve, but I wanted to keep the Left and Right solely for L&R duties without extra bass concerns. |
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Post by cwmcobra on Dec 24, 2020 8:06:43 GMT -5
Great discussion on subwoofer system configuration. I have a quick question of confirmation. I have an XMC-2 on order and will be using it in a 9.4.6 configuration. Since that leaves only the Center Subwoofer channel available, am I correct that I can not separate LFE and BM in this configuration? Seems a no brainer, but just want to confirm that I'm not missing something. I'll be using a miniDSP 2x4HD to manage the subs and could play with having different crossover and PEQ settings for each of the two pairs of subs, but I'm not sure that would make a positive difference. The two sub pairs are Bill Fitzmaurice DIY sealed 15" Tuba HT folded horns and PSA XV15 ported subs. If I could separate the low frequency channels, I would send BM to the Tubas that will be located in the front corners of the room, behind an acoustically transparent screen. Separate LFE would go to the XV15s located in the seating/listening area, connected to the XMC-2 using Emotiva VSUB-1 wireless system to provide location flexibility. Thoughts and comments appreciated.
Merry Christmas to all!
Chuck
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Post by marcl on Dec 24, 2020 8:33:09 GMT -5
Great discussion on subwoofer system configuration. I have a quick question of confirmation. I have an XMC-2 on order and will be using it in a 9.4.6 configuration. Since that leaves only the Center Subwoofer channel available, am I correct that I can not separate LFE and BM in this configuration? Seems a no brainer, but just want to confirm that I'm not missing something. I'll be using a miniDSP 2x4HD to manage the subs and could play with having different crossover and PEQ settings for each of the two pairs of subs, but I'm not sure that would make a positive difference. The two sub pairs are Bill Fitzmaurice DIY sealed 15" Tuba HT folded horns and PSA XV15 ported subs. If I could separate the low frequency channels, I would send BM to the Tubas that will be located in the front corners of the room, behind an acoustically transparent screen. Separate LFE would go to the XV15s located in the seating/listening area, connected to the XMC-2 using Emotiva VSUB-1 wireless system to provide location flexibility. Thoughts and comments appreciated. Merry Christmas to all! Chuck The only way to separate LFE and BM in this configuration is to configure Center Sub as LFE, which would send BM to any speakers configured as Large. You would then connect the miniDSP to the Center Sub output and do gain and time alignment for your four subs in the miniDSP. No need to do any PEQ there, because once the four subs are aligned, Dirac sees the Center Sub output as one sub and will handle the frequency response and impulse response corrections, as well as alignment of the "virtual sub" with the other 15 speakers. If for some reason you wanted to limit the bandwidth of LFE sent to particular subs you could do that with crossovers in the miniDSP. Back to the PEQ question .... I've done some PEQ in the miniDSP and the rest in Dirac, I've done individual sub PEQ at the output stage or overall PEQ at the input stage, and some of each .... in the end, I just trust Dirac to do a better job overall. PEQ filters can introduce some phase shift so cascading them can cause interactions that you have to chase. The simpler route is to let Dirac do it. Note also that you may need to invert the polarity of one or more subs depending on placement. Aligning the subs can be facilitated by using REW to measure the subs individually in their range (like 40-100Hz) for the purpose of getting accurate timing information from the Impulse Response plots in REW. So what if your Large speakers only go down to 40-50Hz and you'd like to have the subs cover that bottom octave or two? You can do this with a little extra hardware. Let's say your L/R fronts are large. Split the outputs, send one split to the front speakers, and send the other split to a combiner and send the output of that to the second miniDSP input. Now you have your Large L/R front signals combined and in the miniDSP. Configure a low pass filter at that input of the miniDSP to the crossover you want ... like 24db/octave at 50Hz. Then mix this signal with the LFE signal in the routing block. Now you have full range LFE AND low passed BM going to all four subs. Here's my setup. The DWMs are planar woofers that augment the bass of my L/R Magnepan 3.7s. But you see how the bass management from the L/R Large speakers ends up at the miniDSP and mixes with the LFE. In my case I low pass the BM at 35Hz.  |
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Post by cwmcobra on Dec 24, 2020 8:46:53 GMT -5
Thanks marcl. Am I interpreting correctly that configuring Center Sub as LFE would send BM to the large speakers only and not to the subs? And the 4 subs would all be LFE only? That will be interesting to try. The LaScala LCRs spec low FR at 42 Hz and the Heresy surrounds at 50 Hz. So if there is any BM content below that, it would be lost in this configuration, correct?
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Post by marcl on Dec 24, 2020 9:08:44 GMT -5
Thanks marcl. Am I interpreting correctly that configuring Center Sub as LFE would send BM to the large speakers only and not to the subs? And the 4 subs would all be LFE only? That will be interesting to try. The LaScala LCRs spec low FR at 42 Hz and the Heresy surrounds at 50 Hz. So if there is any BM content below that, it would be lost in this configuration, correct? You are correct. And that's why (for the cost of a couple splitters and some cable) you can easily route that low BM to the subs and have the best of both worlds. I have my front Magnepans set to Large and all other speakers set to Small. The Small speaker bass goes to the Magnepans, and then below 35Hz everything goes to the subs. And now that I think of it .... if you're using La Scalas for LCR, it's even simpler. Set your L/R to Small crossover at 40Hz. Set the Center to Large. Bass management will go to the Center. Then you just have to split the Center output and send one half to the miniDSP. You could use a Y cable. |
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Post by cwmcobra on Dec 24, 2020 10:20:15 GMT -5
Thanks marcl. That's just the potential solution I was looking for. I have a couple of XLR splitters and cables, so your suggested configuration should be easily attained. In the end, it will all come down to which approach sounds better, of course.
Cheers!
Chuck
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Post by marcl on Dec 24, 2020 10:35:03 GMT -5
Thanks marcl. That's just the potential solution I was looking for. I have a couple of XLR splitters and cables, so your suggested configuration should be easily attained. In the end, it will all come down to which approach sounds better, of course. Cheers! Chuck Cool! And as I have found, there is no doubt that a full range speaker will make ALL the bass sound better (within its limits) than subwoofers built for high output and very low frequency extension. If you need any help with the miniDSP side let me know. To put a low pass filter right at the input you have to use the Advanced setting on the filter block and paste in Biquad coefficients from the calculator included with the plugin. |
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Post by cwmcobra on Dec 24, 2020 13:46:12 GMT -5
Thanks again marcl. I'm a ways away from actually dialing in the system, but appreciate the offer of support!
Chuck
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