Dear @deep_333 @phusis and friends:
Here the mode calculator and other 2 interesting links for almost all of us:
Room Mode Calculator_0.xls (live.com)
Microsoft Word - whitepaper10.doc (harman.com)
R.
Geddes multiple subwoofer method - 3 subs vice 4
Geddes recommends 3 subs for optimal sound - a different perspective
Interesting video depicting Geddes philosophy on using subs. Also, he treats the main speakers as part of the bass solution and does not recommend using high pass filters as this takes away from the total bass capabilities of the entire speaker sub interface system. I am going to experiment this weekend. Also, a higher crossover frequency for the first sub collocated closer to the main speakers is new to me. Recommended above 100 hertz for the first sub and then incrementally lower for the 2nd and 3rd sub in an asymmetric pattern.
I feel like the Geddes approach for sub integration closely resembles what I have been doing for years without even knowing this method. So, my 18” deep bass and 15” mid bass drivers on the field coil speakers become part of the solution instead of being taken out of the equation. That’s what I have been doing and that’s what I thought sounded best to me. Multiple ways to do sub integration but this method is the one that pretty mirrors how I have been doing it for years.
45 responses Add your response
@deep_333 wrote:
Interesting, so you could experiment with two different subs approaches (more on that below) with no restrictions in regards to size.
Infrasonics is a big deal with movies (and even music, to an extend), no doubt, and those who haven’t heard the difference the octave below 20Hz can do here (with select movie source material) obviously don’t know any better. A pair of 15"-loaded high power capacity subs (direct radiating, sealed) crawling low enough would begin to give an indication of infrasonics, but the real impact and significance comes with much larger air displacement area - not intended as an effect per se, but rather reflecting the means of what is really necessitated at frequencies that low to attempt and approximate energy linearity and some kind of minimum headroom. Meaning, if one has the intention of trying to investigate on the importance of infrasonics in one’s home setup, be that with movies and/or music, it’s vital that a surplus of effective cone area - in addition to a lot of power (and proper concrete flooring and overall room construction) - is attained for this purpose, and for most audiophiles that’s likely a lot more than they imagine and care to implement in their homes. Which is a shame, because it’ll be a stone unturned (an important one at that) for many on what infrasonics can do to the experience of sound in general.
I’ve heard of the Devestator subs, yes, though technically they’re not really horns but rather a high order bandpass design (basically ported) that utilizes the output from both the front and back wave of the cone, and which mimics suspiciously close the design of Josh Ricci’s Skram subs, just tuned lower and thereby bigger. If I’m not incorrect the front wave of the cone (the 21" driver is situated, and hidden inside the cab) shoots into a short, expanding slot (or horn), while the back wave is loaded via the bigger part of the enclosure into large, square ports. The output is then summed through the short horn/port sections. The important takeaway here is the higher efficiency compared to typical hifi-ish or even cinephile subs, which is also seen by their larger size (i.e.: Hofmann’s Iron Law), but they’re still good to about ~15Hz or so and would make an interesting ground of comparison to the lower eff. subs in the other room for you to embark on. Technically, my tapped horn subs are also a high order bandpass design, but here the front wave of the woofer fires directly into a compression section and then expands into a regular horn path that via its length dictates the tune of the design (which through the Devestator’s is done via the backwave into the ported cab section), which is why the core of the design is really a horn, and the backwave of the cone is situated close to the mouth area that will then sum with the wave of the horn. If you want to up the efficiency factor further, while maintaining extension down into the 30Hz and (when corner loaded) even 25Hz area, non-truncated front loaded horn subs like the 12Pi horns or similar-ish iteration from John Inlow are the way to go. With this we’re talking a minimum of 105dB sensitivity, and they’re rather massive in size. Imagine the whole front section of the horn being one big mouth area, and it should give you an indication of the power at play here. Really though, it comes down to the sheer quality of bass which is utterly smooth, layered and immersive, and firing these things up to prodigious SPL’s (which requires very little power) the effortless force and presence is something to behold. Hifi subs are mere toys by comparison, sonically and SPL-wise - believe me. The interesting thing for you will be comparing the importance of infrasonics, not least in music, from the low eff. subs with the more extension restricted higher eff. sub counterparts. Myself I’ve opted for the higher eff. solution (full click @25Hz, and rolling off from here) for both music and movies in a single listening space. The price of infrasonics is lower efficiency and a large sub count to add up on the necessary displacement here, and moreover there’s a sonic implication because lower tuned, direct radiating designs simply sound different compared to higher eff. iterations, not least when they have more or less hidden cones. The latter are inherently more musical to me, and to boot they energize the listening space very differently and more effectively than smaller subs.
It’s certainly a much easier process than cutting out the stuff by yourself, which would have also required the proper machinery in a dedicated space and preferably assembly experience. |
@phusis , appreciate the info you provided....I have a couple of rooms in my basement for audio (no WAF issues), 1 for multichannel and the other room for stereo. Size of speakers and subs is not an issue (bigger the better). I recently went up to a pair of the 18inch F18 Rythmik subs for my multichannel room, which go infrasonic, usable output down to 10hz, an entire octave below 20hz technically speaking...All you hear from the naysayers is.."There’s no content that hits that low or ya can’t hear that low", whatever. On the contrary, it’s flipping nuts, the impact these monster subs have on many tracks, that i have heard a thousand times. It’s a new phenomenon, lol.... It is also perhaps a motivation to try out something different in my stereo room....like a pair of large horn subs! My current open baffle GR subs that i have in the same room are good for what they are, but, it’s more for precision (not for the visceral maniac stuff). Have you heard of these Devastator horns? I ran into a couple of AVS threads with guys talking about it.... It looks like they get down to 19hz, comes with all the flatpacks, i.e. seems to be a more complete easier diy kit. I’d hate to stare at drawings and start cutting wood from scratch, not have it be too much of a time investment.
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@deep_333 wrote:
They’re the tapped horn principle, DIY and called MicroWrecker (a sibling to the LilWrecker tapped horn, which has a 5Hz lower tune for a 50% addition in volume (30cf.) and ~3-4dB hit in sensitivity). I got the plans over at AVS Forum from a developer there, and had them built by a cabinet maker. The developer also simulated drivers for the specific design in the Akabak (or Hornresp) software, and so had a range of suitable woofer choices to go with. These have to have the proper electromechanical parameters within a fairly narrow window in a given tapped horn design for them to work the best here, which is to say to properly resonate the horn; too weak a motor and the horn isn’t "excited" enough, and too powerful a motor will compress the air too severely at the throat, also leading to insufficient horn resonation. The B&C 15TBX100 (8 ohm) unit I’m using sits right in the middle of the desired performance window here, and so is close to the ideal driver for the purpose. Close, because it lacks the very last bit of excursion range to be fully exploited at its rated power (1000W nominal power handling, 2 hour pink noise test, free air) before hitting Xmax in this design with a ~23Hz tune, but it’ll take 600W up until that point, so perhaps a theoretical 2dB SPL subtraction overall. Fine with me, as a single MW will still do over 120dB’s down to 25Hz with the B&C unit, and I have two of them - corner mounted. The same driver is used in Danley’s TH-115 subs, but being this tapped horn design has a higher tune the driver can be used at full power here. Size of speakers doesn’t seem to scare you off, but be aware it’s still a 20cf. volume per cab. When you see them "in the flesh" it can a bit unsettling getting a feel for their true size, I know it was for me at first. In the same ballpark there’s also great designs by Josh Ricci over at Databass.com, notably the Skrams, Skhorns and Othorns. The latter is also a tapped horn, though built around the 21" B&C 21SW152 woofer - a beast - and with a ~28Hz tune. Initially I intended to have a pair of the Othorns built, but the woofers were out of stock for months, and so I opted for the MW’s. The Skrams are a great design as well, and more driver "friendly" than the Othorn. Meaning, a range of 21" pro woofers can be used here, whereas the Othorns are only fully pleased with named woofer or its IPAL equivalent. The inspiration for the MW’s were Danley’s TH-50 tapped horn, and they’re very much alike in vital areas. Josh Ricci opted to develop the Gjallarhorn tapped horns instead (also inspired by the TH-50), which is built around TC Sounds LMS-Ultra 5400 driver (18"), but that driver is no longer built. A beast of a sub, and about the most one can squeeze out of an 18" woofer, I’m told. They’re tuned a bit lower than the MW’s, but I never truly considered them as they are too monstrously sized (plus more than 300 pounds w/driver) and a bit hampered in their upper range due to the slightly lower tune. In any case any of the above designs are extremely capable in putting out high quality bass at prodigious SPL’s and low distortion levels - certainly compared to most any low eff. "hifi" subs out there. |
Dear @m-db : " on a used Plus in any size I think you might be amazed. " hings are that I already had the DD Plus experience not in a home system but with an audio distributor. Rally good.
However the pulp/paper cone of my HGS ones are the ideal for my speaker woofers where the DD driver build material is different with a different bass reproduction signature. Thank's for your advise.
R. |
...know about that "plastic’y" sound all too well and it goes all the way up to their top end line. The measurement heavy JBL/Harman PhDs don’t seem to care too much, as long as it measures great! They may need to put their big egos down and learn a thing or two from the likes of Borresen, Yamaha, TAD, etc. What horn subwoofers do you use? DIY? or something else? I might be interested in getting one. |
I'm having difficulty visualizing this with the written description. Do you have a top view sketch/schematic with distances, etc (that you can post here)? "Picture says a thousand words", Confucius said.
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It is interesting how strongly bass affects our perception of audio. Owning the JBL 4367 I more or less agree Phusis take on them but will add my thoughts as this thread is about bass. I have been using them with subs for the last year (60-65hz highpass) and recently got rid of my subs (sold one and gave one to a friend) in prep for new subs on order. With the subs the system as a whole is warm and impactful, I can play them very loud with no ear fatigue at all. But without the subs the speakers seem a touch bright to me (they measure “flat” with a bit of HF roll off in my room). The interesting thing is the subs are the only change and they were measured and adjust flat to 25hz and roll off from there. Now that it has been a month or so without subs the speakers sound a touch warm again. All in all pretty interesting with no change to the mids or highs. Just that lass octave and 1/2. I don’t have much horn experience other than these speakers and demos of the Klispch line (which I did not really care for if I am being honest). I sit 10’ from my speakers and a well damped room, 7” broad band panels at first reflection points, fully treated ceiling, full carpet, big soft fabric theater seats, so that might play into it too. My UHF adjustment is 0.5db down which makes a bigger difference than one might think. The 4367 currently is my favorite speaker I have owned, their flaws are minor at their price point and have honestly given me a moment of pause as I am not sure what I would change too. which leads me to changing my subs and trying a more active approach and I plan to dip my toes into digital correction and see how it goes
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@rauliruegas wrote:
+1
It depends on the particular horns (and amps) too. Auditioning the popular JBL 4367 monitors (which are somewhat smaller than my mains + subs system) I’ve found them too "hot" sounding over longer durations in being more forward and incisive in their sonic nature than my own system. To by fair, in many ways the 4367’s are delightful speakers; exhilarating, energetic, honest, clean, extremely informative (I’d say a wee bit too "insisting") and - apart from the low octave shifting towards a warmer imprinting - fairly coherent. The thing is though, to my ears and sensibilities they simply become too much over time, and moreover I find string instruments like violins to have a slightly "plastic"-like and/or nasal character to them (I prefer the M2’s and 4349’s here with their flatter waveguide), which is a dealbreaker to me. My EV main speakers by comparison with their large format horns + subs are sonically more akin to large panel speakers; more relaxed, less "beamy," fuller and more visceral/physical/dense. Where it becomes apparent they’re a larger package overall, apart from their more natural height of presentation, is at higher SPL’s (not least with movies) where the sheer unadulterated force and power is at full display. It’s what I’ve been saying quite a few times by now: typically, the larger the horn the less it sounds like a horn. Somehow though it goes contrary to what people expect of smaller vs. larger horns in thinking the latter will be too much for its own good in domestic environments (and they may be in smaller spaces), but often it’s the other way ’round and smaller horns sounding more agitated and "aimed" at the listener. Visitors, upon listening to my setup, have often been surprised at the presentation and that it isn’t intrusive or in-your-face. There’s no way around though that horns are more present and in a way more direct sounding with less reflected sound being part of what hits the ears.
I would expect that too. I’m sitting about 11ft. from my mains, and here they cohere and sum very well. The TH subs, flanking the mains in the corners, are carefully dialed in delay-wise through the Xilica DSP.
It’s an experience that’s difficult to explain. Those who’ve heard horn subs often find them to sound more convincingly extended than smaller direct radiating subs, even though the latter may extend deeper on paper. For horns to go below 20Hz very large size is required. Mine roll off below 25Hz, and below 20Hz there’s no information whatsoever - both due to the specific design limitations and that they’re high-passed below 20Hz (36dB/octave BW). |
Dear @deep_333 : My room geometry is not easy to use the Harman calculator, these are more or less the dimensions/shapes: as I posted my apartment has 2 parlors from the entrance door. First parlor where is not seated the system its wall distance to the other extreme, where is the second parlor/listening area/system, are 9.70m to the window that’s behind the speakers. Now the speakers are at 95cm. in front of the windows and the left speaker is at 30cm. from the side wall, the rigth wall is at 8.5m from the left one. The center of the speaker tweeters in between are at 2.60m and the speaker woofers at 3.05m. Listening area length is 4.70m and the wide is around 4.5m. Exist a passageway of 1m. wide by 14+m. in length. This apartment has 3 bedrooms and two complete bathrooms. All in one floor, so is a little big. Dining room is big and the dining room central/rectangular table is for 10 seated people. Both parlors are full of ( mainly ) wood furniture as the dining room and all around exist wood display cabinet ( like seven of them ). The parlor furniture are made from natural absorbtion materials and due to the shape of the wood furniture it works as difussors. Rigth now the system is working truly fine and till today I think that I can’t do ( ? ) anything to improve its very high quality MUSIC reproduction and very high resolution. It does not matters the SPLs the room/system just refuse to distort: MUSIC stage always is there/nothing change but SPL. Yes, its noise floor and distortions levels are so low that can be dangerous to the ears with out taking in count due that we can’t be aware of those distortion levels. No, I normally listen at around 82 or even a little lower db SPL and only during some kind of system audio items tests I listen at 95db with peacks at 105+db for only a few minutes.
R. |
Dear @phusis : " I don't buy into the music vs. HT subs distinction. " Agree, my mistake.
" while I myself opt for horn-based subs.... "
In general I like the immediacy of the MUSIC reproduced sound that's a main live MUSIC characteristic. One " but " on horns ( at least to me ) is that I don't like its reproduced sound seated at near field position ( say 2m. ) I think we need at least no less than 3m. and obviously that depends of the room too. At near field position my ADS are way better than horns or electrostatics. Unfortunatelly I never had the opportunity to listen a true horn subwoofer ( at least that goes to 16hz. ) but I tend to beleive you.
R. |
@rauliruegas If you should happen on a used Plus in any size I think you might be amazed. All the best. |
Dear @deep_333 : I really appreciated your post and you can be sure that I will do all those. Tou touched a critical issue in the subs correct integration to the room/speakers: PHASE that almost no one really speaks about when are talking of subs and " playing "/changing with comes with very high rewards that for me were unexpected to say the least.
By coincidence and before read your post last nigth I was " playing " with subs Phase making some changes ( btw, we modified the phase control in the HGS to go from only two phase positions to almost continuous changes. My HGS have several modifications made it by a friend and me: I changed the stock internal wiring from the drivers to the amp for pure silver KK cable, I by-passed all the internal fuses and changes passive and active parts in the input board and internal crossover circuit board. Even I change the damping foam by long hair virgen wool. The subs are at around 20 cm. from the floor and have a dead weigth of 30kg at the top plate. ) and I did it using CD MUSIC source as " Day after Tomorrow " that at its very first track comes with deep bass made/using synthesisers and I use other film soundtracks as Gladiator and the like and late in the nigth I gone to sleep but not totally satisfied. So, I wake up early today and followed playing with phase changes this time doing with LPs mainly using the Telarc 1812 that has a wide kind of different bass frequency ranges and recorded with acoustic instruments and not synthesiser that’s different and after the changes with the phase finally I was truly satisfied with and learned the critical importance of PHASE about. Thank’s for your knowledge advise. I’m just learning what it’s exiciting to me in that critical sub/speaker subject. Thank’s again.
R. |
@rauliruegas , An L shaped room makes things a bit more complicated on the sim domain. Talk to an integrator. It is hard to write technical essays on a thread. Nevertheless, the harman room mode calc will still work between any 2 parallel walls in that room. Google harman room mode calculator. You would enter your room dimensions to determine where the hell all the strongest nulls/peaks are. The results would look like this....
Here’s another way to visualize it....(top view, scratch rough sketch)....Also how you deal with nulls and peaks. Goofy bass is all a guy hears unless he does stuff like this. (Basic Physics - Standing waves/nulls/peaks occur between parallel walls). This again shows you the advantage of larger rooms. The smaller the room, the harder it gets to deal with this.
Here’s some expansion on what i was trying to describe with the Harman virtual sub principles. By strategic placement of subs, you can get rid of many of the strongest peaks/nulls upto the sub’s crossover frequency. For nulls/peaks occurring at frequencies higher than the sub’s crossover, you have no other choice but absorption. In short, you can use subwoofers to REMOVE nulls/peaks. It is not just for giving some oomph on the low end for a flaccid speaker.
If you had 4 subs, this is how you would place them and phase adjust them to get rid of the maximum number of the strong nulls/peaks in light of the above mentioned principle (up to the sub’s crossover point). sub 1: 1/4 lengthwise, 1/4 widthwise position sub 2: 1/4 lengthwise, 3/4 widthwise position sub 3: 3/4 lengthwise, 1/4 widthwise position sub 4: 3/4 lengthwise, 3/4 widthwise position.
If you only have 2 subs, sub 1: 1/4 lengthwise, 1/4 widthwise position sub 2: 3/4 lengthwise, 3/4 widthwise position.
Same principle works for the room’s heightwise modes. You ever heard of guys lifting subwoofers off the floor to the heightwise modal points? That is the reason and the physics behind it. The idea is to tackle the max number of strong nulls/peaks with sub placement...and then use absorption to deal with the rest (modal nulls/peaks/frequencies higher than the sub’s crossover). It is also a very very good idea to get subwoofers with a variable phase knob (not just a 0/180 phase switch). Rythmik is a good example of subwoofer brands that give you a variable phase knob.
Everything else should be diffusion so you don’t kill the room with absorption all over the place. Focus only on the main listening position. Hope that helps you...and some of the other confused guys here...
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Dear @deep_333 : I agree with you in everything and specially in " I am only concerned about my main listening position. ". My 2 subs are rigth at the front stage side looking each to other: the drivers sound reproduction does not goes " direct " to me as the sound from the main speas.kers. My room is an inverted L with two parlors ( first smaller one ) in the second and main parlor is where the speakers/subs are seated in front of my listening position. Exist a left side wall behid de left sub but the rigth side sub has not a direct wall because there is is the dining room a big one with wood furniu.ture. Through several months maybe over 1 year I tested every imagined subs positions and was exactly where are seated today what works in that room/system. Even that I can be seated at 4m. from the speakers my prefered and day by day listening sessions are at 2.5m ( around ).
R. |
@rauliruegas wrote:
Velodyne, REL and whatever else don't hold a monopoly on bass reproduction that's especially suitable for music. Subs that are deemed mostly that are usually too small to be an effective Home Theatre equivalent, and so they're really only good in the context of music reproduction at less than elevated SPL's. Home Theatre subs tend to be bigger (sometimes much bigger), for good reason, but the popular crux appears to be that many of them are ported variants. Whether ported or sealed is not the issue for me, but rather overall design execution and adherence to physics; both principles can deliver very good bass performance, but being sealed subs are usually smaller I'd wager they're winning the most hearts. Therefore, as you can surmise, I don't buy into the music vs. HT subs distinction. Look at the DD18+ review and the section quoted by you. Obviously it's very good at HT duties in addition to music, so the two are not mutually exclusive - it's about having enough effective cone area to cover both bases, and moreover added cone area and higher efficiency equals lower distortion and a cleaner, more effortless bass. Win-win. Speaking of which: sealed or ported are only two ways to go about it. Some prefer open baffle iterations, while I myself opt for horn-based subs. Horn subs don't suffer from low efficiency or port noise, and with tapped horns in particular the horn itself does the heavy lifting, not the driver. High efficiency into the lower octaves means a very large air radiation area, and thus very little cone movement (especially from TH's, which have excursion minima at the tune) - even at prodigious SPL's. This is both the most musical, smooth, effortless and naturally full bass I've heard, and as well the most visceral, indeed downright scary powerful bass for movies to boot. The catch: they're large. |
There are all kinds of guys making things too confused on different threads... - Basic physics - standing waves/peaks/nulls occur between 2 parallel walls...Ya "effectively" absorb on those 2 parallel walls just as it pertains to your listening position to mitigate it....and leave the rest of the walls alone for absorption (i.e., don't suck the life out of/kill the room). Get the Harman room mode calc and plot your room modes, for starters. I am not concerned about what happens anywhere else in the room, no corner crap nothing.... I am only concerned about my main listening position. For example, It's a li'l strange to me when i see guys put a bunch of crap in the corners and all over the place as if they are hanging around/dancing around in a corner. I "effectively" absorb down to 30 hz with my ACDA panels on the front wall, back wall, left wall, right wall for my primary listening position (modes check, sbir check). Yes, they are 16 inches thick and weigh 220lbs each for a reason. I use a couple of different lighter panels on the ceiling for the same purpose and to take care of some floor/ceiling bounce issues. - That's it...no more absorption...Everything else i use is diffusion (first reflection, ipsilateral, contra, etc, whatever to boost perceived resolution, detail, spaciousness and so on for the listening position) - I don't usually put subs on the front stage for show...Refer to the harman paper - virtual sub principles, especially If restricted to 2 subs (very few people set up more subs than 2) Reading the results of a room mode calculator will guide you more on placement for the same purpose. In fact, you can mitigate a certain amount of modal issues with multiple subwoofers, placement and phase adjustment (a bit trickier to do), except only up to the crossover point of the subs...For something higher, you would need absorption. In short, follow the physics...and when you do, you may rejoice/float around in a uniform warm womb of bass....the core foundation for jawdropping sound.
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Dear @deep_333 : " " Not true...depends on what you get...I use 8 of the acoustic fields ACDA panels ....clean down to 30hz. "" Problem with room treatment and especially in the bass range because its main importance is that " clean down to 30hz ". First question could be at which frequency starts to " clean " and if exist in room measurements of frequwency response with and with out those kind of panels. Always is important not only what we are avoiding with but what we are losting with, obviously always exist trade offs and depends of each one of us what kind of trade off we are ready to take. Other alternative is something as the C20 electronic bass trap that operates between 15hz to 150hz :
AVAA C20 - Active Bass Trap - PSI Audio
I don’t have a dedicated room/system and when I had professional room treatments ( several kind of through the years. ) I really never been totally satisfied with. At random with the stuff in my parlor as wool carpets and the kind of the parlor furniture and treatment diffusors and curtains and mainly to the subs position I’m lucy enough to stay really satisfied as ever with no apparent troubles in all the room/system frequency range quality level reproduction at diffrent S¨PLs and different kind of MUSIC. In the other side and about the ported loudspeaker still today is what almost all top manufacturers use it and the customers jut buy because there are not to many sealed/acoustic suspension speaker alternatives. Even Wilson uses ported. For subwoofers I totally agree: must be sealed not ported.
R.
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Not true...depends on what you get...I use 8 of the acoustic fields ACDA panels...250 lbs each, 16 inches deep (a bear to handle, obviously need a larger room to handle this stuff)...takes care of business clean down to 30 hz.
Agreed, I recently got a pair of the 18 inch sealed Rythmiks, replacing 2 of my F12G for certain types of music..visceral soul churning slam fest down to an octave below 20 hz, can't make this stuff up. |
@phusis : " Looking at the CEA-2010 maximum peak output of the DD18+ puts it in the upper middle range of all subwoofers ever tested and near the top of all sealed subwoofers. It produces output easily in excess of 110dB over the critical music range and offers impressive deep bass output as well mustering over 103dB at 20Hz and almost 99dB at 16Hz which is impressive for a sealed subwoofer. The DD18+ CEA-2010 output is amplifier limited above 20Hz and was distortion limited at and below that point. The DD18+ is the first commercial subwoofer that I have ever evaluated that was able to produce a CEA-2010 passing result at 10Hz. 86.1dB may not seem like much but any passing result at the 10 and 12.5Hz bands denotes rather prodigious deep bass output capabilities due to the amount of displacement involved to produce any meaningful output that low in frequency, not to mention that distortion must be under some amount of control as well. If distortion is ignored completely the DD18+ can almost muster 90dB at 10Hz. "
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Dear @phusis : Velodyne ( at least my HGS, not the DD models with Kevlar driver. ) were made for MUSIC sound reproduction systems and not HT where needs are different and especially on SPL. The Velodyne aceleromete/servo ( patented. ) avoid that THD can goes over 0.5% and when it’s approaching that figure power gone lower but not the bass frequency.
I never had a problem with my HGS and maybe because my main speakers has 95db efficiency but I measured at my seat position ( near field. ) 97db SPL with peacks at around 105db and the bass range is fabolous. I readed other reviews on the DD models where what you read it did not happens but at the ned the critical subject is to mantain ( for listen MUSIC not HT. ) the THD at minimum in the bass frequency range. This is the why of my post more than about thisor that sub.
In your link review we can read this ( HT ):
" Batman Begins followed by the Dark Knight, both of which offer not only a very powerful and engaging audio track but also are enjoyable movies to watch. The master volume was set to -15 for the entirety of both films. Throughout the various action and dramatic sequences of the films the DD18+ provided a stellar performance. Subtle background bass undertones were just that and when demanded the DD18+ provided a lot of power and room shake. On sections that contained deeply extended bass the DD18+ had generous extension that provided an extra feel or size to the sound that lesser subwoofers simply do not. As previously discussed the performance of the DD18+ as far as definition and ability to track notes is excellent. If there was any small caveat to the DD18+ performance it might be that it was not quite as sharply dynamic on a few parts as I recall they can be, the tumbler chase scene being one example, the gatling gun test, bankers shotgun blasts and the hospital explosion being others. My large listening room acoustics are such that it is very difficult for a single subwoofer, even a very capable and powerful one such as the DD18+, to handle alone so perhaps the DD18+ was being limited a little on a few extremely loud sections. Audio memory is a hazy thing at best so I can’t be sure and to be quite honest I’m stretching to find even that small caveat with the DD18+’s audible signature. It is that good. What I can be sure of is that the DD18+ always sounded composed throughout and easily produced one of the top performances that I have experienced from a single subwoofer in my room. Very deep bass was presented with apparent ease and fundamental tones or pitches of bass transients were spot on. "
Not so bad as those measurements and the reviewer seats one DD-18 at 4 meters from his seat position, not near field.
R.
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My subwoofers offer high pass connectivity and filtering. The manufactures instructions suggests: If your main amplifier has difficulty driving your main speakers bass to your satisfaction then give the subs high pass circuit a try. If your main speakers are small and lack bass then give the subs high pass a try. I love the way my amps drive my speakers low bass. A few of my older LP's simply sound better with the subs off. Since these subs multi parameter, frequency band auto optimization does so well matching the speakers low frequency presentation, high pass filtering is noticeably wasted. Surprisingly, this decade old twenty minute optimization software quickly and easily solves much of todays hifi subwoofer setup and integration issues.
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@audioquest4life wrote:
For your 15" and 18" woofers to have the "Geddes effect" they'd have needed to be properly spaced apart, and not placed in the same pair of speakers. What you can do however is using your no doubt great Classic Audio Loudspeakers in their intended full-range mode as two bass sources, and then add two subs placed along the opposing wall or side walls for a 4 bass source DBA. |
@rauliruegas wrote:
True, but..
Let’s get real - there’s no magic bullet here. According to the Audioholic’s review a single Velodyne DD18+ won’t even reach 120dB’s; it runs out of steam just above 115dB’s - at 50Hz and ~7% distortion. At 20Hz it’ll do some 103dB’s with a distortion level going well beyond 20% at this output. By all accounts these are very respectable numbers for a sub this size, but after all - it’s just physics and their limitations. What you’re referencing (i.e.: 120dB’s with no more than 0.5% distortion) is close to impossible with anything other than a truly gigantic subs system that wouldn’t fit anywhere practically. You want low distortion in the lower octaves at higher levels you need much more displacement, and in effect efficiency and size. No technological trickery with small, low eff. cube subs will do that, unless multiplied in significant numbers at a very hefty price tag (unless it’s a DIY approach). Go high efficiency with 2-4 large boxes (likely also DIY) on the other hand is another matter. So, lower distortion in the bass area is very important indeed, but to get there there’s no way around what I just specified above. Few however are willing to do what it takes, if they even realize it. Instead they resort to finger pointing and calling the likes of stacked sub towers flanking main speakers for being "overkill" and what not, thinking their puny and expensive cubes are all what it takes. If only they knew.. Excerpt from named review.
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Dear @james633 : Mainly I'm talking of MUSIC home/system reproduction where the whole frequency range belongs/"lives" through the bass range. As better the bass range in any audio system as better the whole quality MUSIC reproduction levels. That's why THD in the bass range is just so critical due that high THD levels as the JTR ( that are for HT not MUSIC: ) subs afects all the whole MUSIC frequency range system due that the different bass frequency ranges develops harmonics that has direct influence in the midrange and from here to the HF range. You are fine with that 5%-10% on THD and no problem with me, it's only that's way to high in frony/against the 0.5% at 120 db in the Velodyne. We can have a perfect room/system sub blend with a " marvelous " frequency chart but the main issue down there is not that perfect blend but the developed THD level by the subs inside the subs system range at seat position. That's all, it's not about to subs it's about MUSIC reproduction quality level.
Just my way of thinking, R. |
As for digital vs apologue I think we are talking about crossovers and less so sources. If you want an all analogue system (vinyl) and want to stay that way analogue is the only option but there is not really a way to correct timing. As for digital crossover out of a digital source good implementation should be pretty transparent if everything stays digital and at least as transparent as adding all the parts in analogue options. In my limited experience both options have been fine and it comes down to the particular piece. |
Rauliruegas, A good sub is a good sub, JTR is just ugly (I have a mixed theater room, painted black, so no big deal). Not sure THD matters too much as they are all good and far out pace even the largest of speakers. Integration is most important. At any rate they have a trial period so I will see soon. Not really looking to debate subs, they all perform well but some data from audioholics. The E112 at 105db-ish /25hz has 25% THD and the JTR is 05% at 105db-ish. The perlisten 215 is 3% at the same volume/hz but 3 times the price. Both JTR and Perlisten are digging deep into infrasonics and should just be cruising at 60hz under 100db. Velodynes are nice subs, I have not heard one in 20 years though. |
Dear friends: For me exist a critical issue to use DSP for the high-pass filtering and blend the subs to the mains. The question is for each one of us way of listening MUSIC. I own thousands of LP's and only hundreds of CD and I really don't care about streaming even that today digital in many ways surpass the analog alternative but due that I listen mainly to LPs I can't contaminates the overall analog signal doing it that pass through a digital domain . Apples can't mix with oranges at least for me. Main difference between analog and digital and where digital outperforms analog is in the bass range but even that I know that I prefer to stay all the way down to analog but as I said: this is me and only an opinion.
R. |
Dear @james633 : " I don’t see anyone using JTR stuff for music.." Well the main reason is that JTR subs are designed for HT in specific and not for MUSIC systems. In HT THD is not to important and even that the enty level RS1 measured more or less " fine " its THD goes to high but your JL are not way better in that regards and certainly not only in the RS1 price range but with out the " impact " in the low bass that has the RS1.
Btw, it looks a lot to the Velodyne 18"/15" that are higher in price but more important is that Velodyne's THD goes at 0.5% thank's that the design checks in real time over 16K times each second the woofer excursions. In the other side: " I would like to try 4 at some point.." Of course you can but at one specific seat position we need only 2 subwoofers and Harman showed 30+ years ago why even that in its study said the optimal are 4 for the " room space " not one and only seat position as with dedicated MUSIC system .
R. |
I am going to dip my toes in a digital solution soon. I got rid of my JL subwoofers (with apologue high-pass) and ordered new subs (JTR RS1). This time around I am going to try the MiniDSP SHD for sub integration. Not sure the MiniDSP will be good enough for a long term solution for me (clean enough? Maybe?) but it will let me try different filters and what not (has its own PEQs, and Dirac too). If I like the solution I will try something more highend as money allows. The SHD is limited to two subs and I think I would like to try 4 at some point
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There is no right one way to setting up a subwoofer system, but there are some common denominators. The first is as @erik_squires described, a complete two way crossover is mandatory preferably digital because this is the only way to accurately time align the individual drivers. @james633 With a 64 bit floating point processor running at 24/192, DSP is totally invisible. There are only sonic advantages and no disadvantages as long as good DACs are being used. The most important concept that Geddes advances is the use of multiple subs also championed by @audiokinesis. Two is the minimum, I use 4 as does audiokinesis. @audioquest4life It is not the size of the woofer that counts, it is the frequency range it operates in. The higher a woofer goes the more important is the use of a high pass filter. Many large woofers are running up to 350 or even 500 Hz. This is well into the midrange. Middle C is 256 Hz. Bass under 100 Hz will cause doppler distortion of everything else carried by the driver. The is also no such thing as too much head room. You also have to use a filter if you plan on time aligning the drivers which IMHO is mandatory. Another important concept is running low bass with up to 20 dB of gain. This gives you the visceral character of a live performance. If done right it does not make the bass warm or boomy it just increases the vibratory sensation of the music. My favorite curve increases bass at 4-5 dB/oct from 100 Hz down. 20 Hz is hot by 10 dB. Some rooms may require more. The room is key. I am very fortunate as my listening room was designed as such and there is no back wall. The room opens to the rest of the floor which is acting as one big diffusor. So in my situation I am listening just as much to the drivers as I am to the room whereas most people are listening more to the room. Another important factor that was mentioned was room treatments for bass do not work. It is a total waste of money which could have been spent on another subwoofer or a better crossover. @erik_squires I have no idea in this day and age why someone would use a ported loudspeaker. We have loads of powerful amplifiers and digital signal processing can give you any reasonable frequency response you require. Subwoofers in particular should always be sealed as port noise is ubiquitous with the amount of air moved by a subwoofer driver. The effect of lowering many types of distortion including IM, Harmonic and Doppler and increasing headroom is just as important as adding low bass when using subwoofers with two way crossovers. Good for you. Now try getting this into the heads of most subwoofer users who are being sold a bunch of malarkey by the manufacturers. |
Well I’m glad to see that several on this thread, including @audiokinesis are taking up the issue of distortion and dynamic range of the mains being something worth considering when adding subs. :) Too often that behavior gets overlooked for one reason or another. |
Earl Geddes investigated both symmetric and asymmetric placement of multiple subwoofers and concluded that asymmetric placement following a few basic guidelines was superior. Nothing against Todd Welti’s study of symmetrical placements, but there are other options. As for whether or not to highpass filter the mains, the short answer is, it depends. If the main speakers and/or their amplifiers are being taxed, then it makes sense. In @audioquest4life’s situation, his main speakers have approximately sixteen times the cone area of a 6.5" midwoofer, and probably at least twice the excursion. Those interested can do the math. Ideally any highpass filter in the main speakers’ signal path is not audible to the point of being detrimental. I have customers who have tried it both ways and use a protective highpass filter, and customers who have tried it both ways and do not. When I design main speakers with subwoofers in mind, I tend to give them sufficient excursion-limited headroom that a protective highpass filter is optional instead of mandatory in most applications. Duke |
Dear @lonemountain : I don't know if you know the Harman Subwoofer White Papers that are a scientific modeling used to avoid standing waves and those null points, it's truly extensive and here Harman Inernational ( JBL between other audio items. ) conclusions:
" 74 CONCLUSIONS • How many subwoofers are enough? Four subwoofers are enough to get the best results of any configuration tried. Two subwoofers is very nearly tried. Two subwoofers is very nearly as good and has very good low as good and has very good low frequency support as well " That's at room/system seat position. Top speaker manufacturers with passive designs use the passive crossover ( high-pass, band-pass, low-pass and the like ) to blend " perfectly those speaker used drivers and not only the crossover but time alignment and several other issues. There are several ways to implement the high-pass filter when using a pair of self powered true subwoofers with out " problem ". In my case ( audo system ) the high-pass was implemented at ampifiers input doing only a change in the input value capacitor that comes/came by amplifier design and blended almost " perfectly " using the subwoofers own low-pass filters , phase and volume. Never is an easy task to blend the mains with subs but it can do with a little of patience . Btw, my subs are ( acoustic suspension. No ported/reflex. ) positioned in front of the main speakers and facing each to the other not looking to the seat position as the main speakers but side to side ( I don't know how to explain it. ). R. |
“The reality is that in many cases the negative sonic effect of the DSP platform may be less than the negatives of not using delay at all or filtering the mains and creating phase issue.” I agree with this statement. Any negative of high-passing or time alignment is greatly out weighed by the positives. |
I agree with Geddes and this he is one of the few out there with the right idea. ATC has always agreed with "don't insert another filter in a very audible place" idea when adding a sub. Our efforts on the pro side with multiple subs have worked every time in solving room bass issues, especially avoiding bass build up on the back wall (behind your listening position) and nulls in the space that you cannot resolve due to console placement (which would parallel a sofa position in a home listening room). So we follow the plan that multiple, smaller, lower SPL level subs located on different walls (if at all possible) seems to give us the most even bass in the listening space. What appears to be more important than high pass filtering the mains (which inserts a very audible dip in response at 80-125 and gets worse with distance of mains to sub) is adding delay to the mains. This part ATC does not agree on inserting a DSP across the entire audio band to accomplish this mains delay, as you can "hear" many of these DSP platforms. This is why they stick with an analog input to not force you to listen to a permanent unchangeable DAC. The DSP effect is certainly as audible as cable differences, or differences between DACS, CD players or other digital sources. The reality is that in many cases the negative sonic effect of the DSP platform may be less than the negatives of not using delay at all or filtering the mains and creating phase issue. Brad |
Dear @audioquest4life : @erik_squires is rigth even with bigger speakers than monitors smaller ones and I disagree with Geddes.
In the other side you are doing nothing new and nothing as what Geddes says because you are talking of what speaker manufacturers do: midrange, mid bass and bass no matters wich kind of drivers they use in their speaker designs ( field coil or not ). It depends what the manufacturer is looking for and at which market price he wants to offer.
R. R. |
"I will always disagree with using the main subs without a high pass filter as being universally better, especially with smaller mains." That may be true for small speakers. I guess my giant mains with aforementioned 18" and 15" bass drivers don’t fall in your small speaker category, so I am safe from ridicule for using the Geddes method. Diversity of thought is such a valuable thing to embrace. Not many people get it.
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I will always disagree with using the main subs without a high pass filter as being universally better, especially with smaller mains. The distortion produced by smaller woofers in the lowest octaves is measurable and limits the overall dynamic range of the main speaker, ESPECIALLY with ported speakers. Plugging speakers used with subs can also further dramatically increase the available dynamic range of the mains. If you are placing 4x12" or larger subs, then I can’t imagine most main speakers have much to contribute, besides distortion. If all you care about is maximum bass dynamic range, with no thoughts given to distortion, I guess Geddes is correct. If you care about the entire dynamic range envelope then a high pass on the mains may be just the thing. |
