And then there is infinite baffle, in (through) wall, subs that can go incredibly low with very little effort.
That's awesome. I was probably thinking about the newer 18 inch drivers, which I have only seen in their commercial designs.
Thanks for the update.
Best,
Anand.
I bought my sub drivers two years ago. They don't sell the 18's for DIY use and after just checking their site, they also are not selling the 15's either anymore. So you can only get the built subs from Rythmik with the 15" and 18" drivers.
Well said
8xAE-IB-15. Takes it down so low, it's only limited by what the room size can reproduce. The front wave NEVER meets the back wave.
8xAE-IB-15. Takes it down so low, it's only limited by what the room size can reproduce. The front wave NEVER meets the back wave.
Attachments
Jazz Man,
I just realized I thought about asking you what you meant with that OB bass doesn't carry any distance, but forgot to do it. Could you ellaborate what you mean?
I spent some time on this. Josh at Data-Bass measured mostly 21" drivers so not too helpful. He did measure 15" MTX drivers, but those aren't available here and I had never heard of them before so not for me.
Josh liked the Rythmik 18" sealed quite a bit. This sub did show compression at 115 dB SPL outside measured at 2 meters and on long term use (as opposed to peak of 115dB SPL indoors...). I could certainly live with that!
I'm not aware what a Klippel is so Googled "BMS 18N462 Klippel" and only hit on your post, so I'm wondering what you were referring to.
Anyway, I went onto UniBox and modeled several pro 18" (B&C, Faital, Beyma, Eminence) in sealed boxes of 150 and 200 liters and while they are all 93dB+ efficient they displayed about 15dB drop by 20Hz...so not really so efficient. A 95dB-efficiency driver (at 100Hz) that is 80dB by 20Hz will need to be equalized/DSP to be flat from 20Hz or so...that is why so much amp power is needed I guess.
I'm going to dig more, but here's where I'm arriving at now. BTW, Rythmik's site shows their 15" available for DIY - not the 18" though. The 15" Rythmiks require 3 cubic feet (85 liters) in a sealed box, so also smaller than the pro drivers. I confess I was linking the idea of 18" pro driver subs, but it's looking like the 15" Rythmiks with servo might be a better option (despite looking small vs my 18" Faital mibasses 😀)
You can think of it as the opposite of an IB, the front and rear waves will meet at some distance and largely cancel out.
I'll take some time, and go through some of this for you
I'm not aware what a Klippel is so Googled "BMS 18N462 Klippel" and only hit on your post, so I'm wondering what you were referring to.
I only found a BMS 18N862 Thiele-Small
Here's an explanation of "klippel" https://www.klippel.de/fileadmin/kl...ts/KLIPPEL Speaker Component Measurements.pdf
There seems to be an ongoing large scale mis-understanding of what it takes to produce deep bass. This is evidenced by the continuing notion that di-poles are even considered for deep bass. Deep bass needs HUGE boxes. Or they need HUGE closets/garages/or what-ever else spare space one might have. We can get by with moderate sized boxes using pro woofers, but in the majority (but not all) cases the bottom octave will remain elusive. Bottom Octave=16-32 Hz. Huge refrigerator size boxes often times do not sit well in domestic settings, hence the compromises start. That's why the sub-woofer driver was invented. When I started this adventure back in 1974, sub-woofer drivers weren't available. We used the rare 15 with low Fs, and as close to the optimum Q, as we could find. Vas was simply a fact to be dealt with. Dave Wilson was young back then, too. He sourced a German company, Magnat, for an 18inch. Look back in history, for the size of THAT thing. Most PRO woofers do NOT like to be installed in sealed boxes. A PRO woofer that excels in the mid-bass is not going to do so well in the deep bass. We then get to the fork-in-the-road to where we are considering a ported box for mid-bass, and a sealed box for bass. Sorry, but they usually don't mix well. How to get them to blend, is beyond the scope of this particular rant, as it's still devoted to deep bass. I have achieved really good test results with the RSS series of sub-woofer drivers from PE. The Ultimax might be better, but I have not tried any of those. The RSS 18 inch will perform well in a 4 cubic foot box, but it will be only of moderate efficiency. Multiple units are the answer, for more than just one reason. I suspect they will perform pretty good in a home theater based system. Many of the folks only use the one (HT) system, but, for the very-few that have a dedicated 2-ch analogue system, I would not use the RSS sub-HT approach. For a 2-ch system, we want old school woofers, huge boxes, a mix of tubes and Class-A solid sate, and a 2-track reel-to-reel. I state this NOT as a trip down memory lane, so much as an illustration to what superb sound quality is all about. Most of the audio folks today, will have not heard such a system. This is why they remain steadfast in their [also] modern day belief systems.
Anyway, I went onto UniBox and modeled several pro 18" (B&C, Faital, Beyma, Eminence) in sealed boxes of 150 and 200 liters and while they are all 93dB+ efficient they displayed about 15dB drop by 20Hz...so not really so efficient. A 95dB-efficiency driver (at 100Hz) that is 80dB by 20Hz will need to be equalized/DSP to be flat from 20Hz or so...that is why so much amp power is needed I guess. Data-Bass: Subwoofer Measurements
Horacio, just for fun, why not model the BMS 18N862 in a proper vented box, to illustrate the difference, between it, and sealed. Interesting here, that you should point out 80db SPL at 20Hz, when a di-pole will be even worse.
I'm going to dig more, but here's where I'm arriving at now. BTW, Rythmik's site shows their 15" available for DIY - not the 18" though. The 15" Rythmiks require 3 cubic feet (85 liters) in a sealed box, so also smaller than the pro drivers. I confess I was linking the idea of 18" pro driver subs, but it's looking like the 15" Rythmiks with servo might be a better option (despite looking small vs my 18" Faital mibasses
And finally, there is this: Data-Bass: Subwoofer Measurements
I'm not aware what a Klippel is so Googled "BMS 18N462 Klippel" and only hit on your post, so I'm wondering what you were referring to.
I only found a BMS 18N862 Thiele-Small
Here's an explanation of "klippel" https://www.klippel.de/fileadmin/kl...ts/KLIPPEL Speaker Component Measurements.pdf
There seems to be an ongoing large scale mis-understanding of what it takes to produce deep bass. This is evidenced by the continuing notion that di-poles are even considered for deep bass. Deep bass needs HUGE boxes. Or they need HUGE closets/garages/or what-ever else spare space one might have. We can get by with moderate sized boxes using pro woofers, but in the majority (but not all) cases the bottom octave will remain elusive. Bottom Octave=16-32 Hz. Huge refrigerator size boxes often times do not sit well in domestic settings, hence the compromises start. That's why the sub-woofer driver was invented. When I started this adventure back in 1974, sub-woofer drivers weren't available. We used the rare 15 with low Fs, and as close to the optimum Q, as we could find. Vas was simply a fact to be dealt with. Dave Wilson was young back then, too. He sourced a German company, Magnat, for an 18inch. Look back in history, for the size of THAT thing. Most PRO woofers do NOT like to be installed in sealed boxes. A PRO woofer that excels in the mid-bass is not going to do so well in the deep bass. We then get to the fork-in-the-road to where we are considering a ported box for mid-bass, and a sealed box for bass. Sorry, but they usually don't mix well. How to get them to blend, is beyond the scope of this particular rant, as it's still devoted to deep bass. I have achieved really good test results with the RSS series of sub-woofer drivers from PE. The Ultimax might be better, but I have not tried any of those. The RSS 18 inch will perform well in a 4 cubic foot box, but it will be only of moderate efficiency. Multiple units are the answer, for more than just one reason. I suspect they will perform pretty good in a home theater based system. Many of the folks only use the one (HT) system, but, for the very-few that have a dedicated 2-ch analogue system, I would not use the RSS sub-HT approach. For a 2-ch system, we want old school woofers, huge boxes, a mix of tubes and Class-A solid sate, and a 2-track reel-to-reel. I state this NOT as a trip down memory lane, so much as an illustration to what superb sound quality is all about. Most of the audio folks today, will have not heard such a system. This is why they remain steadfast in their [also] modern day belief systems.
Anyway, I went onto UniBox and modeled several pro 18" (B&C, Faital, Beyma, Eminence) in sealed boxes of 150 and 200 liters and while they are all 93dB+ efficient they displayed about 15dB drop by 20Hz...so not really so efficient. A 95dB-efficiency driver (at 100Hz) that is 80dB by 20Hz will need to be equalized/DSP to be flat from 20Hz or so...that is why so much amp power is needed I guess. Data-Bass: Subwoofer Measurements
Horacio, just for fun, why not model the BMS 18N862 in a proper vented box, to illustrate the difference, between it, and sealed. Interesting here, that you should point out 80db SPL at 20Hz, when a di-pole will be even worse.
I'm going to dig more, but here's where I'm arriving at now. BTW, Rythmik's site shows their 15" available for DIY - not the 18" though. The 15" Rythmiks require 3 cubic feet (85 liters) in a sealed box, so also smaller than the pro drivers. I confess I was linking the idea of 18" pro driver subs, but it's looking like the 15" Rythmiks with servo might be a better option (despite looking small vs my 18" Faital mibasses
And finally, there is this: Data-Bass: Subwoofer Measurements
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Oh boy. Hope you are feeling better after taking that chip off your shoulder through the rant.
You are jumping to conclusions without understanding what I'm saying. The point is not which alignment is more efficient. Obviously OB for bass is inefficient. Anand was pointing to the higher efficiency of pro drivers, which is true, and my point was that when you set up those pro drivers for sub duty they aren't as efficient unless you use huge boxes.
Example, per your request: BMS 18n862 is 94dB efficient at 1 W and 1m, but put into a sealed 85 liter box it's about 77dB at 20Hz (1W, 1m) and 94dB at 200Hz. Apply 250W and you get 100dB SPL at 20Hz and this great driver has Xmax to spare and at 250W it's at 8.5mm vs 19mm Xmax, so could be pushed harder. And will likely have low distortion per the displacement being below 50% of Xmax. Doubling sealed box size to 170 liters we get 103dB SPL at 20Hz. I don't care for vented boxes.
Now take the Rythmik DS1502 which is smaller and only 89dB efficient, yet applying 250W (50% of the plate amp nomilal power) also delivers 100dB SPL at 20Hz, although displacing 13mm vs 15mm Xmax. Maybe higher distortion, but the servo does help so don't really know. So my point is that Rythmiks make sense in smaller sealed boxes vs the pro drivers I've modelled despite being less efficient. Don't mean that Rythmiks are a special breed vs other sub drivers - just one brand I have had very good results with. With servo.
Maybe if you reread the post you'll noticed I had dropped the idea of OB subs, so my focus was Rythmiks vs pro drivers in sealed boxes. 4 sealed subs delivering 100dB at 20Hz in a smallish room should do ok for my music listening.
A labyrinth, such as my 17-foot sub, while requiring a rather elaborate box is in the same acoustic family as an OB and IB.
17 foot pipe sub 12-230 Hz ±5dB
B.
17 foot pipe sub 12-230 Hz ±5dB
B.
I don't feel any different today, than I do any other day when the absurd notion of a di-pole is proposed for "sub" bass. Your phobia of the vented box is shared by many. Alas, you have reached a solid foundation based conclusion as to what will work bet for your situation. That is an OUTSTANDING accomplishment, particularly considering all the flooby dust that circulates in these various audio discussion sites. You might want to read through this again:There seems to be an ongoing large scale mis-understanding of what it takes to produce deep bass. This is evidenced by the continuing notion that di-poles are even considered for deep bass. Deep bass needs HUGE boxes. Or they need HUGE closets/garages/or what-ever else spare space one might have. We can get by with moderate sized boxes using pro woofers, but in the majority (but not all) cases the bottom octave will remain elusive. Bottom Octave=16-32 Hz. Huge refrigerator size boxes often times do not sit well in domestic settings, hence the compromises start. That's why the sub-woofer driver was invented. When I started this adventure back in 1974, sub-woofer drivers weren't available. We used the rare 15 with low Fs, and as close to the optimum Q, as we could find. Vas was simply a fact to be dealt with. Dave Wilson was young back then, too. He sourced a German company, Magnat, for an 18inch. Look back in history, for the size of THAT thing. Most PRO woofers do NOT like to be installed in sealed boxes. A PRO woofer that excels in the mid-bass is not going to do so well in the deep bass. We then get to the fork-in-the-road to where we are considering a ported box for mid-bass, and a sealed box for bass. Sorry, but they usually don't mix well. How to get them to blend, is beyond the scope of this particular rant, as it's still devoted to deep bass. I have achieved really good test results with the RSS series of sub-woofer drivers from PE. The Ultimax might be better, but I have not tried any of those. The RSS 18 inch will perform well in a 4 cubic foot box, but it will be only of moderate efficiency. Multiple units are the answer, for more than just one reason. I suspect they will perform pretty good in a home theater based system. Many of the folks only use the one (HT) system, but, for the very-few that have a dedicated 2-ch analogue system, I would not use the RSS sub-HT approach. For a 2-ch system, we want old school woofers, huge boxes, a mix of tubes and Class-A solid sate, and a 2-track reel-to-reel. I state this NOT as a trip down memory lane, so much as an illustration to what superb sound quality is all about. Most of the audio folks today, will have not heard such a system. This is why they remain steadfast in their [also] modern day belief systems.
Whoa. might need paragraphs to get around my dyslexia.
So it seems like you have a lot of good knowledge and experience to share to the forum. Why do we see you mostly on someone else's dipole thread trying to convert them to an enclosed box solution? Why not also give advice on other aspects of the design and debate the merits of those? Or start your own threads?
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Hi Lewinski,
Are you able to do some basic tests with scrap baffles and such in your lounge room?
I have had good open baffle systems and if I had no cost constraints, WAF constraints or neighbor issues (I live in an apartment) I would run pair per side 12" servo subs to around 40hz-60hz with room correction for the subs. Crossed to 15" pro audio woofer. But big dipole woofers work well too if you have the space for lots of large woofers in your room. I have tried both ways when I lived in a house.
Are you able to do some basic tests with scrap baffles and such in your lounge room?
I have had good open baffle systems and if I had no cost constraints, WAF constraints or neighbor issues (I live in an apartment) I would run pair per side 12" servo subs to around 40hz-60hz with room correction for the subs. Crossed to 15" pro audio woofer. But big dipole woofers work well too if you have the space for lots of large woofers in your room. I have tried both ways when I lived in a house.
Good morning, sir. Or good day to you as I see you are from down under. I have already done all as you suggest. Can't say as the last time i started my own thread, though (maybe never ?). It's not so much as I am trying to "convert" someone. It's more of a effort to clarify and educate regarding open baffle/ di-poles as there is so much false information floated around by some.
There was some really good dialogue surrounding the consideration of a cone driven horn (for mid-range), back circa 2015. Both classes 101, and 102 started by Mr. Lewinski.
But........"no good dead goes unpunished"
I understand what you are getting at, above. But you do realize that when both sides of the cone of a driver operating as a dipole are not enclosed by any "box" they experience the same thing as they would find in a very large (e.g. room sized) box? This has the advantage of allowing the driver to operate near its resonance with something very close to the "free air TS parameters" similar to an infinite baffle system. In both cases, the low frequency efficiency of the driver in terms of SPL per Watt of input power is maximized. To clarify, I am talking about the driver's nearfield output above, not the farfield one.
The challenge with dipole "bass" is combining the driver's nearfield response with enough front to back pathlength to reduce cancellation, as much as necessary (see my point on this below). There will always be some amount of cancellation with a dipole system - that is unavoidable. But the question of whether dipole bass is practical and sufficient for output down to 20Hz (lower is not really practical) is really just a matter of proper design and application.
As I have mentioned many times, the room size plays a very important role in whether or not any dipole bass system can produce enough SPL at very low frequencies. The room MUST be rather large in order for a dipole subwoofer to work. By large I mean some dimension of 40 feet (12m) or more to reach 20Hz. Smaller rooms seem to "short circuit" the front and rear output of the dipole. This is why I often suggest a closed box subwoofer below 80Hz, and this also simplifies the design of the OB/dipole speaker quite a bit as well. But that is mainly because most people do not have a good understanding of the room size requirements for dipole subwoofers. I am trying to help them to get a good result more than I am trying to bash dipole subboofers with such a statement.
What would probably be more productive in this discussion would be to compare the performance in the 20Hz-40Hz octave for dipole and sealed systems in terms of SPL and efficiency. The monopole sealed box will always win in terms of subsonic output (e.g. below 20Hz) as well as max SPL, but in a home environment there is not real need to exceed 110dB at 20Hz for most people.
When you constrain the max SPL and LF extension to reasonable values, and have a large space to listen in, a dipole "subwoofer" can work well, sound good, and meets all the necessary requirements.
My buddy told me once how much better a Ferrari was than a Nissan GTR. After he ran out of breath, I told him that it didn't matter, they both gotta drive 5km/h in traffic. Same for bass. Whilst not subsonic, almost every dipole system I heard was more enjoyable than many conventional setups in laypeoples houses. Also, like my 5km/h analogy states, sometimes having the ability to produce deep bass is counterintuitive to what you're trying to accomplish. Lots of different goals in hi-fi.
Some people who have "the ability" to produce big bass with monopole subs, do a horrible job employing it. It's like watching a Mustang leave Cars and Coffee. There is a fine line between chaos and control. Writing off dipole as this flawed concept would be a lot easier to stomach if the alternative was as universally great as some suggest. Not everyone has a house or location where they can chase 20hz like it's some fountain of youth. That's where dipoles shine IME. I'll take music over an eviction notice any day.
Some people who have "the ability" to produce big bass with monopole subs, do a horrible job employing it. It's like watching a Mustang leave Cars and Coffee. There is a fine line between chaos and control. Writing off dipole as this flawed concept would be a lot easier to stomach if the alternative was as universally great as some suggest. Not everyone has a house or location where they can chase 20hz like it's some fountain of youth. That's where dipoles shine IME. I'll take music over an eviction notice any day.
I shortened Charlie's quote a bit, just to keep the site's preferences happy. Readers are encouraged to go back and read his post in it's entirety.
With respect to "both sides of the cone". Yes. But bear in mind that the rear of the cone is in anti-phase to the front of the cone. Thus, we are not picking up double the effective cone area. The averaged baffle size sets up the point of cancellation starting. As frequency descends lower, the cancellation is greater. The one kool thing is, though~~ the cancellation is somewhat linear when considered in, and of itself, and will be 6db/oct until Fs, where it then descends at 18db/oct. But, we are only concerned with getting down to Fs. Here's where another important point comes up. The purveyors of the OB for bass tend to recommend "pro" style drivers. Well, that's both good and bad. The good is (but not limited to) they can sound REALLY really good. [THAT] they are flexible in what size box they can be used in, also lends itself similarly (but to a lessor degree) to be used with no box at all. Depends quite a bit on the various Q factors. The bad part is, pro woofers tend to have a higher FS than their hi-fi counterparts.
We can take a time-out here and actually answer the OP original question, and suggest the Acoustic Elegance drivers for such a task. The AE drivers have already been suggested a couple of times before, in this rather lengthy thread.
Now, at this point we must realize these devices are going to be used in a listening room. For sure, the larger the better, and the closer to a rectangle vs. a square the better as well. If we accept the concept that mono-pole bass interacts with the room boundaries, we must also accept the notion this will happen with OB bass as well. If mono-pole bass has points along the frequency curve where just the right (meaning wrong) distance can have a cancellation effect, then this can occur with OB bass as well **EXCEPT* this interference is now of a positive constructive force. In either case this is not of linear fashion. It is frequency select. The difference between the two bass systems is that mono-pole is omni, where-as OB is figure eight. Thus, with the mono-pole, there is greater flexibility in placement of the device. The often used marketing slogan for OB bass is, "they interact with the room less". Well, yes, kinda-sorta. But that's not the entire story. It's more like a head-line from a biased news source. The OB bass device absolutely needs the room to have a chance of sounding somewhat acceptable. Mono-pole does not. Take both outside and see whatcha got.
As far as OB in a large room/large venue, I seem to recall a very good report on such an attempt at one of the various European Triode Fests. This could be the 40+foot room Charlie was talking about. As I recall it used a baffle of about 12 feet wide, by eight feet tall. Several Altec 15's, and probably a horn(or horns) for the mids/highs.
Now, contrast this effort to the oft described notion that seems to be peddled among some, but not all, of the contributors here on this forum:
"getcha a 18x42 inch plank, cut a hole for a woofer, put a 15mH choke in line with it, and MARVEL at the extreme high quality bass you will have"
Well, I know of such a guy who drank this kool-aide. I was a bit too late. He followed one of the gurus' advice and bought an Alpha-15. I asked him to report back after he installed it. He even built an "H" frame. He proclaimed it sounded like crap. In the mean time, I taught him how to build a proper enclosure for a 12 inch pro-woofer that I selected. I mean I taught him step-by step. He said, "Man this has far exceeded my expectations". Of special note here, is, he also built an LX-521 about 5 years ago. He uses it in a different room, then what he built upon my recommendations. He lives in a VERY large home. In partially keeping with Barenek's Law, he says he loves the 521, but admits that the degree of money involved and all the processing to get the thing to sound good, he wished he had taken my approach much earlier. For about $900.00 in materials and a HUGE amount of sweat equity, he has himself a pair of speakers comparable to at least $5000.00 in retail. Probably even more.
The end.