Well I'm still waiting for a price but I decided to see what kind of box Elemental Designs could make for me. My wood working skills are ok at best, and some of what I wanted to do would more easily be achieved with a CNC machine. Elemental has such a machine and will build boxes to your design and specifications for a fee, though previous quotes from them have been very reasonable.
I have the HF version of the 12" RS series Dayton subwoofer and the 500 watt Dayton amp. Currently its mounted in a Dayton 2 cubic foot sealed box lined with dampening material. I was not happy with this subwoofer, and decided I wanted to try a better built box ported and tuned to a very low frequency. I modeled this woofer and came up with two boxes I liked, a 3.5 cubic foot box tuned to around 25hz and a 4.5 cubic foot box tuned to around 21hz. I decided to go with the larger of the two, and I'm having a 1.5" thick MDF box made with heavy bracing and a slot port tuned to 21hz, or so. It will weigh about 130lbs before the woofer and amp are added. I'm also going to upgrade the parts in the amp a little, replace the power supply caps with some better quality caps of larger size, and bypass them. I'm going to upgrade the opamps as well with some AD825's I have around. The box will come in plain MDF, so I'm going to veneer it with a wood veneer. My last veneer project came out great, so I'm excited to see how this comes out. I will post pictures once its finished, but thought I would talk about it now before I commit to anything. Looking for thoughts and feedback from all of you.
I have the HF version of the 12" RS series Dayton subwoofer and the 500 watt Dayton amp. Currently its mounted in a Dayton 2 cubic foot sealed box lined with dampening material. I was not happy with this subwoofer, and decided I wanted to try a better built box ported and tuned to a very low frequency. I modeled this woofer and came up with two boxes I liked, a 3.5 cubic foot box tuned to around 25hz and a 4.5 cubic foot box tuned to around 21hz. I decided to go with the larger of the two, and I'm having a 1.5" thick MDF box made with heavy bracing and a slot port tuned to 21hz, or so. It will weigh about 130lbs before the woofer and amp are added. I'm also going to upgrade the parts in the amp a little, replace the power supply caps with some better quality caps of larger size, and bypass them. I'm going to upgrade the opamps as well with some AD825's I have around. The box will come in plain MDF, so I'm going to veneer it with a wood veneer. My last veneer project came out great, so I'm excited to see how this comes out. I will post pictures once its finished, but thought I would talk about it now before I commit to anything. Looking for thoughts and feedback from all of you.
Im currently in the middle of a sub woofer project myself, and I encourage you to go for it if u want personally i build my own enclosures because id rather spend my money and other things but if you want it done right then by all means do so but the only thing I see that I would do differently is the tuning of your cabinet, i know the sub is a great sub but for a 12" 21 Hz is calling it close and unless you want a really flat response from it I'd go with the 25 Hz tuning but that's me and 130 lbs, I'm only 15 and i like big and bad too but 130 lbs is a little much for just a 4.5ft^3 enclosure, instead of the 1.5" MDF I'd go with 1" or maybe 1.25" MDF and just dampen it with 3/4 material.
The 1.5" enclosure thickness is because they work with 3/4" sheets and combine them. The only choices are 3/4" or 1.5". If I had my choice I would go with a 1.5" baffle and 1" for the rest. However, for the strongest and least resonant box possible, thicker is better. I've really never found dampening material to offer enough of an improvement to go with it over a thicker box. The bracing is quite imense as well, which contributes to the large weight.
As for the tuning, going with the 25hz tuning requires the smaller box to be flat, and probably would give me a -3db point in the 20-22hz range, which is pretty darn low. I believe it would also give me increased output in the range that matters most. However, I have heard various boxes at various tunings and really like the sound of a box tuned down that low. I think for now I will stick with the lower tuning. I also don't believe that its too much for that woofer, it models quite well with that setup.
I actually have built quite a few boxes now myself, but having worked with both my own cuts and those from a CNC machine, as long as I can afford it, I prefer it. I'm sure a better wood worker with better tools could do a perfectly adequate job, but I have found thus far that I can't easily match the quality I get from machine cut wood. All the edges are cut at 45's so that when they meet up I have a good strong 90. THe bracing is cut with great accuracy and can be made to press up against the woofer magnet for added strength and resonance control. I recently finished a computer speaker project that involved some Tangband drivers, and I made the enclosures myself, and the quality was fine for that. I also made the enclosures for my brothers Scan Speak based monitors, which came out great. I just wanted something better, and I really didn't have time to make the box myself, so I decided to have it fabricated.
As for the tuning, going with the 25hz tuning requires the smaller box to be flat, and probably would give me a -3db point in the 20-22hz range, which is pretty darn low. I believe it would also give me increased output in the range that matters most. However, I have heard various boxes at various tunings and really like the sound of a box tuned down that low. I think for now I will stick with the lower tuning. I also don't believe that its too much for that woofer, it models quite well with that setup.
I actually have built quite a few boxes now myself, but having worked with both my own cuts and those from a CNC machine, as long as I can afford it, I prefer it. I'm sure a better wood worker with better tools could do a perfectly adequate job, but I have found thus far that I can't easily match the quality I get from machine cut wood. All the edges are cut at 45's so that when they meet up I have a good strong 90. THe bracing is cut with great accuracy and can be made to press up against the woofer magnet for added strength and resonance control. I recently finished a computer speaker project that involved some Tangband drivers, and I made the enclosures myself, and the quality was fine for that. I also made the enclosures for my brothers Scan Speak based monitors, which came out great. I just wanted something better, and I really didn't have time to make the box myself, so I decided to have it fabricated.
Should be a great project and a lot of fun. I think the 1.5" walls is a bit over kill. I'm building a new pair of subs with 4.5 cu ft enclosures. The drivers are 15" JBL 2235H. These JBLs are monsters with 20 lb magnets. I am only using 3/4" MDF as it is recommended by JBL for this enclosure. I'm going to use rosewood veneer. Should look very sharp. Don
I agree it will look sharp. However, as for the 1.5" being overkill, again, have you compared. I mean, if the idea is to make a box that is as non-resonant as possible, 3/4" really isn't very good at that, especially in the bass region, where the energy is greatest. I'm a big fan of mass loading in general, I prefer mass loaded turntables, isolation devices, speaker stands, etc. In the case of this subwoofer, I want to try a mass loaded enclosure. I currently have a 3/4" box, and it resonates horribly, and its even braced internally.
I would also note that some of the modern 10"-15" woofers with 20mm+ of xmax have been known to destroy 3/4" boxes. Examples are the car subs like Kicker L7 solobarics and JL Audio W7 subs, inwhich the companies had to recall the first boxes they shipped them in because the subs were cracking the boxes. Knowing how these companies operate, and knowing that they would not have moved to a 1" thick box unless they had to, given the extra cost, I would say that in some cases 3/4" is not only not thick enough from a resonances stand point, but also pure strength.
I know my own sub only has something like 12-14mm of xmax, and would not destroy a 3/4" box, but again, I'm doing it for mass loading. I want a box that will not contribute any of its own noises to the project.
I would also note that some of the modern 10"-15" woofers with 20mm+ of xmax have been known to destroy 3/4" boxes. Examples are the car subs like Kicker L7 solobarics and JL Audio W7 subs, inwhich the companies had to recall the first boxes they shipped them in because the subs were cracking the boxes. Knowing how these companies operate, and knowing that they would not have moved to a 1" thick box unless they had to, given the extra cost, I would say that in some cases 3/4" is not only not thick enough from a resonances stand point, but also pure strength.
I know my own sub only has something like 12-14mm of xmax, and would not destroy a 3/4" box, but again, I'm doing it for mass loading. I want a box that will not contribute any of its own noises to the project.
I'm not familiar with the car woofs you mentioned, but more than likely they are sealed enclosures which can have tremendous internal pressure. Since you are building a ported enclosure you don't have to design for this problem. However, It's not my place to try and talk you out of something you've already given thought to. If properly designed and tuned your port will relieve the excessive stress on the enclosure. If not your port will be blowing air and sounding like gale force winds.
I'm a fan and believer in JBL speakers. My feeling is that a company that designs, builds, and markets speakers that cost in excess of $30K is a good source of technical info. They recommend using 3/4" properly braced MDF for the 4.5 cu ft 2235H driver.
What I'm building is a different looking, yet functionally equivalent JBL B380. And, in doing so following JBL's design specifications. Don
I'm a fan and believer in JBL speakers. My feeling is that a company that designs, builds, and markets speakers that cost in excess of $30K is a good source of technical info. They recommend using 3/4" properly braced MDF for the 4.5 cu ft 2235H driver.
What I'm building is a different looking, yet functionally equivalent JBL B380. And, in doing so following JBL's design specifications. Don
I understand your feelings Don about JBL. I happen to disagree simply from the fact that JBL sells 30,000 speakers having little bearing on their enclosure building skills. What you have however is a pro-woofer which is capable of far less excursion and force than the woofers I'm talking about. Such a woofer probably can easily get away with a thinner enclosure without having an impact on sound.
As for the JL and Kicker thing, the original issue was with sealed boxes. However, Kicker then had problems with the ported boxes falling apart as well, and went with thicker MDF. The problem they had is that the woofers basicly vibrated the MDF apart around where the speaker mounted, causing the screws to strip out, and the wood to fall apart. The solution became a thicker box, though I imagine that t-nuts might have worked just as well.
As for our disagreement on box thickness, I think this is because we are attacking the reproduction of bass from two very different directions. You are using a large prowoofer in a setup that will offer greater efficiency in its band. However, it will either require a much larger box, or will not play as deep, or as loud in that deep range, while also having greater distortion, potentially. Though I am not able to measure my setup yet, it should be able to play flat down to 21hz, and have a -3db point around 19hz. It should have a peek output at around 115 decibles free space, and so probably closer to 120-125 decibles in room. Your setup will more than likely play closer to 120-125 decibles free space, and so potentially much louder in room, but will not be playing as low, and one might argue not as loud in the sub bass region. Like I said, I think we are attacking bass from different perspectives and will achieve different results.
Many of the highend home audio companies, JBL included, use boxes in excess of 1" thick in the highend products. Some companies like Wilson or Aerial go so far as ot build boxes in the 2-4" thick range to reduce vibrations, and it has even measurable impacts on the performance of the speaker. My goal with this project was to once and for all develope a subwoofer that will match the performance of the very high end subwoofers from companies like Aerial, that I had used and liked. Just FYI, the cost of a 3/4" box was 200 dollars and 50 dollars to ship, the cost of a 1.5" box is 260 dollars and 60 dollars to ship. I find the 70 dollar difference in cost minor in the scope of the project, and well worth the potential benefit. If nothing else I won't have to worry about anyone trying to steal my subwoofer.
As for the JL and Kicker thing, the original issue was with sealed boxes. However, Kicker then had problems with the ported boxes falling apart as well, and went with thicker MDF. The problem they had is that the woofers basicly vibrated the MDF apart around where the speaker mounted, causing the screws to strip out, and the wood to fall apart. The solution became a thicker box, though I imagine that t-nuts might have worked just as well.
As for our disagreement on box thickness, I think this is because we are attacking the reproduction of bass from two very different directions. You are using a large prowoofer in a setup that will offer greater efficiency in its band. However, it will either require a much larger box, or will not play as deep, or as loud in that deep range, while also having greater distortion, potentially. Though I am not able to measure my setup yet, it should be able to play flat down to 21hz, and have a -3db point around 19hz. It should have a peek output at around 115 decibles free space, and so probably closer to 120-125 decibles in room. Your setup will more than likely play closer to 120-125 decibles free space, and so potentially much louder in room, but will not be playing as low, and one might argue not as loud in the sub bass region. Like I said, I think we are attacking bass from different perspectives and will achieve different results.
Many of the highend home audio companies, JBL included, use boxes in excess of 1" thick in the highend products. Some companies like Wilson or Aerial go so far as ot build boxes in the 2-4" thick range to reduce vibrations, and it has even measurable impacts on the performance of the speaker. My goal with this project was to once and for all develope a subwoofer that will match the performance of the very high end subwoofers from companies like Aerial, that I had used and liked. Just FYI, the cost of a 3/4" box was 200 dollars and 50 dollars to ship, the cost of a 1.5" box is 260 dollars and 60 dollars to ship. I find the 70 dollar difference in cost minor in the scope of the project, and well worth the potential benefit. If nothing else I won't have to worry about anyone trying to steal my subwoofer.
Ok I just ran the woofer you mentioned in WinISD Pro, which is what I use for speaker box design, and compared it with the the 12" dayton woofer I am using. Now mind you, I have no way, without measuring, of knowing how distortion will compare, but going by the difference in technologies used, I would just imagine that it would be lower with the dayton. I know someone did do measurements and found it to be one of the lowest distortion woofers on the market, and in a sealed box had distortion on part with servo systems, or so was said.
However, having both in 4.5 cubic foot boxes, both tuned to 20hz, my sub will play flat down to 20hz, your sub will not. Its minus 3db point is 49hz, mine is 19hz. Maximum spl with the power limits and between 0-60hz puts them at about the same, just around 115 decibles. The Jbl being slightly more, but that is at around 60hz. Now in the defense of the JBL, I will say that if you take room gain into account, it should play closer to 20hz, as it is about 10 db's down at 20hz. However I have never found room gain to be the best way to round out the frequency response, I find bass to sound lacking when I rely on it. However, my experience with designing a box to be flat through the range I want it to perform in causes it to sound as I like, with full bass extension.
However, having both in 4.5 cubic foot boxes, both tuned to 20hz, my sub will play flat down to 20hz, your sub will not. Its minus 3db point is 49hz, mine is 19hz. Maximum spl with the power limits and between 0-60hz puts them at about the same, just around 115 decibles. The Jbl being slightly more, but that is at around 60hz. Now in the defense of the JBL, I will say that if you take room gain into account, it should play closer to 20hz, as it is about 10 db's down at 20hz. However I have never found room gain to be the best way to round out the frequency response, I find bass to sound lacking when I rely on it. However, my experience with designing a box to be flat through the range I want it to perform in causes it to sound as I like, with full bass extension.
As your research demonstrated the 4.5 cu ft enclosure is not ideal for the 2235H. It functions far better in an 8 cu ft (or so) enclosure. I'm going with the smaller foot print for practical reasons. As I recall the enclosure is tuned to 29 hz, but I may be wrong on this. Because the driver is compromised in the small enclosure it requires a 5 db bump at 25 hz to keep it flat. I have an Ashly EQ to provide this, and a pair of 700 WPC SS monoblocks (one for each sub).
The 2235H/2245H are not the loudest subs JBL makes, but considered by many to be the best in terms of sound quality. JBL makes car subs that can move more air and make more noise, but the trade off is in how well they reproduce the music.
I'm currently using a pair of subs I build with Infinity Kappa 12.1D car audio drivers. It's truly amazing how nice they sound. I was surprised considering the drivers on cost about $100 each. Don
The 2235H/2245H are not the loudest subs JBL makes, but considered by many to be the best in terms of sound quality. JBL makes car subs that can move more air and make more noise, but the trade off is in how well they reproduce the music.
I'm currently using a pair of subs I build with Infinity Kappa 12.1D car audio drivers. It's truly amazing how nice they sound. I was surprised considering the drivers on cost about $100 each. Don
The Dayton driver modeled quite well, and you can see how the small enclosure dampens the 2235H below 30hz (this is where the 5db bump at 25hz comes in). Many people run the B380 without the 5db bump as the freqs below 30hz are out of the hearing range for most of us over 40 years old. Since most of what we hear as bass is in the 40hz to 80hz freqs it's important to keep that part of the curve flat. Don
An externally hosted image should be here but it was not working when we last tested it.
I don't understand why your images look different from mine. This is an image from my version.
I would like to know, how do you get them to handle 800 watts, I found them to overload beyond 250-300 watts. I understand that having too much isn't a bad thing, gives you some headroom, but seems like you won't use much of that 800 watts. I know some people really like the sound of drivers like the JBL's, I think they definatly sound different. It's not my taste, and thats this hobby really, we find an area we like and go with it. I'm just now starting to get into high efficiency speakers, but I still find myself not liking the sound of efficient large woofers in large boxes and horn tweeters/midranges. I will say, the ability to give realistic dynamics is impressive, if I could get that with the sound I prefer from home audio drivers would be ideal.
I would like to know, how do you get them to handle 800 watts, I found them to overload beyond 250-300 watts. I understand that having too much isn't a bad thing, gives you some headroom, but seems like you won't use much of that 800 watts. I know some people really like the sound of drivers like the JBL's, I think they definatly sound different. It's not my taste, and thats this hobby really, we find an area we like and go with it. I'm just now starting to get into high efficiency speakers, but I still find myself not liking the sound of efficient large woofers in large boxes and horn tweeters/midranges. I will say, the ability to give realistic dynamics is impressive, if I could get that with the sound I prefer from home audio drivers would be ideal.
Don't know what's up with the different graphs. I'm just a hacker who enjoys the DIY projects at a somewhat superficial level.
You're absolutely right about the 2235H power handling. My amps have considerably more power than required to drive the subs. I don't listen to music a high volumes. My mid-freq speakers only have a pair of 60 WPC tube mono-blocks driving them. Rarely do I have the volume over 25%.
Enjoy the ride and have fun building the new sub. Be sure to post pics when finished. I'm always interested to see the designs and finishes others come up with. Don
You're absolutely right about the 2235H power handling. My amps have considerably more power than required to drive the subs. I don't listen to music a high volumes. My mid-freq speakers only have a pair of 60 WPC tube mono-blocks driving them. Rarely do I have the volume over 25%.
Enjoy the ride and have fun building the new sub. Be sure to post pics when finished. I'm always interested to see the designs and finishes others come up with. Don
As for the different graphs, I'm wondering if we are using different version of the program. I'm using the Alpha Pro version, you might be using the older program, which is supposed to be less accurate, but is a more complete program with less errors. Other possibility is that you models the HO instead of the HF sub maybe? Although, the HO models pretty bad in a 4.5 cubic foot box.
After redoing the numbers for the dayton sub, fixing some issues, completing it more, checking the specs on the JBL, I finaly began to see models that looked like what I expected. Somehow, I was getting peak SPL that was almost identical for both of our subs, and given the efficiency difference, I just didn't believe that was likely. I found a mistake in my dayton sub specs which was making it more efficient than it should be. I also had the xmax in wrong, I had it as 19mm instead of 14mm, which made it look as if it could play louder without problems. Once that was fixed I got the graphs you see, and then looking through the other graphs, I see that the JBL offers 5-10 decibles more output between 50 and 80hz. It drops off quite a bit more below then, however, like I mentioned before, given room reinforcement, I bet that JBL sub will be quite nice down as deep as most music.
My main reason for wanting a sub that could play so low, even at the expense of some output, was to get a more realistic sound from a few types of music I like which goes quite low. One is organ music, which I actually do like listening to, and find just doesn't have the realistic impact and depth that a real one does. The other types are synthesized music which has 30hz on down synthesized into the music, and though I don't listen to it often, or even much at all, I wanted to know it was being reporduced correctly. I also think its useful in movies, which this sub pulls doubly duty for, as a lot of explosions go down into subsonic range. However, I have always felt that my subwoofer projects have not done the best job on Stand-up Basses low end, or of the lower end of Piano's, etc. I wonder if I might find a more realistic sounding subwoofer if I tried a project like yours, or possibly another good 15" woofer from another company. I liked the one from Usher, its specs are nice, power handeling is good, might work quite well. My original thought on this would be to make woofer/speaker stands to go under my current speakers. By having a pair, I could have them play from 50hz up to 150-250hz, and then have my speakers take over after that. I thought that by having a good set of woofers under each speaker, I would get that better lower midbass range I was looking for, but the cost is high, and I haven't bothered yet. Some day maybe. All sorts of projects I want to try and haven't yet.
After redoing the numbers for the dayton sub, fixing some issues, completing it more, checking the specs on the JBL, I finaly began to see models that looked like what I expected. Somehow, I was getting peak SPL that was almost identical for both of our subs, and given the efficiency difference, I just didn't believe that was likely. I found a mistake in my dayton sub specs which was making it more efficient than it should be. I also had the xmax in wrong, I had it as 19mm instead of 14mm, which made it look as if it could play louder without problems. Once that was fixed I got the graphs you see, and then looking through the other graphs, I see that the JBL offers 5-10 decibles more output between 50 and 80hz. It drops off quite a bit more below then, however, like I mentioned before, given room reinforcement, I bet that JBL sub will be quite nice down as deep as most music.
My main reason for wanting a sub that could play so low, even at the expense of some output, was to get a more realistic sound from a few types of music I like which goes quite low. One is organ music, which I actually do like listening to, and find just doesn't have the realistic impact and depth that a real one does. The other types are synthesized music which has 30hz on down synthesized into the music, and though I don't listen to it often, or even much at all, I wanted to know it was being reporduced correctly. I also think its useful in movies, which this sub pulls doubly duty for, as a lot of explosions go down into subsonic range. However, I have always felt that my subwoofer projects have not done the best job on Stand-up Basses low end, or of the lower end of Piano's, etc. I wonder if I might find a more realistic sounding subwoofer if I tried a project like yours, or possibly another good 15" woofer from another company. I liked the one from Usher, its specs are nice, power handeling is good, might work quite well. My original thought on this would be to make woofer/speaker stands to go under my current speakers. By having a pair, I could have them play from 50hz up to 150-250hz, and then have my speakers take over after that. I thought that by having a good set of woofers under each speaker, I would get that better lower midbass range I was looking for, but the cost is high, and I haven't bothered yet. Some day maybe. All sorts of projects I want to try and haven't yet.
I understand your desire to have the subs as stands for the other speakers. My current subs function as such, and I've designed the new subs (2235H) to do the same. I'm copying the design of this Yamaha sub for the 2235H enclosures. Just scaled it up in size. These will have the rosewood veneer.
Since I x-over the subs at 80hz there are times when you can hear/feel the direction of sound. Having two with one under each of the other speakers it eliminates the problem. It also lifts my L100s and stacked 2405H slot tweets to the proper listening elevation. Don
Since I x-over the subs at 80hz there are times when you can hear/feel the direction of sound. Having two with one under each of the other speakers it eliminates the problem. It also lifts my L100s and stacked 2405H slot tweets to the proper listening elevation. Don
An externally hosted image should be here but it was not working when we last tested it.
yeah I have a theory on why subwoofers benefit from being placed under the main speakers. One is potential mechanical noise that the cabinet, driver, etc. makes. If a sub is near a corner, and it excites that corner, causing something as simple as a wall outlet to shake, suddenly you can tell the direction of the bass. Any mechanical noises that arise from the cabinet, such as port noise, suspension noise, the amp ratteling, voice coil slap, etc. All of these things are much higher in frequency than what the sub is supposed to reproduce, and are very directional, as we all know. I know, subs aren't supposed to make those noises, and a properly sized one for the system won't, but I still find that even high end subwoofer amps have parts that rattle, port's still might make a noise from time to time, and controlling vibrations in the room is very difficult.
Then you have the arguement over how directional bass is, I'm quite certain it isn't, if its clean and free of any higher order fundamentals, overtones, harmonics, whatever. These shouldn't come from the recording, as the crossover should filter those out, but I do wonder if the speaker could potentially be making them. For instance, when you play a 20hz tone, and you can readily hear it, more than likely its harmonics, and some of those harmonics I have heard above what the speaker crossover point is, 60hz. My current sub is so much better than previous ones in this regard that it is much more non-directional than any I have had before. It has no self noise, its limits exceed my listening levels by huge amounts, distortion is very low, etc. The only problem I had was a lack of really low bass energy, and I wanted a tad bit more output. I also like the sound of ported subs better I think.
Then you have the arguement over how directional bass is, I'm quite certain it isn't, if its clean and free of any higher order fundamentals, overtones, harmonics, whatever. These shouldn't come from the recording, as the crossover should filter those out, but I do wonder if the speaker could potentially be making them. For instance, when you play a 20hz tone, and you can readily hear it, more than likely its harmonics, and some of those harmonics I have heard above what the speaker crossover point is, 60hz. My current sub is so much better than previous ones in this regard that it is much more non-directional than any I have had before. It has no self noise, its limits exceed my listening levels by huge amounts, distortion is very low, etc. The only problem I had was a lack of really low bass energy, and I wanted a tad bit more output. I also like the sound of ported subs better I think.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.