derrickdj1 Posted June 12, 2016 Share Posted June 12, 2016 Well summer is here and time for another project. I planning on replacing to subs this year. I'm getting geared up for the BackBum Buster sub. I will use this nearfield behind a sectional sofa couch. The ideal is to get the driver within 4 inches of the sectional. The subwoofer height will be position where half will be firing under the seat and the other half at the lower back. The candidate driver will most likely be SI DS4, 1200 watt RMS. 2 Quote Link to comment Share on other sites More sharing options...
Scrappydue Posted June 12, 2016 Share Posted June 12, 2016 Why ported? Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted June 12, 2016 Author Share Posted June 12, 2016 We did some experiments in the ULF thread on different system and ported delivered more tactile response *TR). it is a matter of spl intesity and particle velocity. I am still thinking about it tonight. Another option is to just some of my exiting drivers and do a large dual box sealed 12 cu ft UM 18 and two 6 cu ft boxes to completely surround the sectional couch. The dual box would be 48X32X 18. This can be made to look like a sofa table and something similar for the two six cu ft. boxes using the SI drivers. This would give me four seal 18's and four vented. I may need to model all of this out and see where I am. The goal is no more subs than I currently have. SPL in not that important, as long as I can hit 115 db at 20 or 17 Hz. The second goal is to increase TR because that is really what we are after in the HT. The UM 18 and SI 18 HT like big boxes. The large sealed boxes will need less power, dig deeper, and have a bigger mid bass punch. By Monday I will make up my mind on going sealed or ported. The ported box in the pic is tuned to 15 Hz. 1 Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted June 13, 2016 Share Posted June 13, 2016 For the average home theater maybe a closed sub would make a difference....not in your though. The vented idea works great, and whether you use the DS4 or the UMAX18 I think the way to get something new and improved is to go with a box size you haven't had yet. A lot of the DS4 models seem to be shooting for around 20CFT, and the extension you would have that way, right behind the couch would give you the benefits of a closed sub with 4 drivers in it potentially. But opening the door on an even larger box may tempt you to change the others too... Quote Link to comment Share on other sites More sharing options...
ZEUS121996 Posted June 13, 2016 Share Posted June 13, 2016 We did some experiments in the ULF thread on different system and ported delivered more tactile response *TR). it is a matter of spl intesity and particle velocity. I am still thinking about it tonight. Another option is to just some of my exiting drivers and do a large dual box sealed 12 cu ft UM 18 and two 6 cu ft boxes to completely surround the sectional couch. The dual box would be 48X32X 18. This can be made to look like a sofa table and something similar for the two six cu ft. boxes using the SI drivers. This would give me four seal 18's and four vented. I may need to model all of this out and see where I am. The goal is no more subs than I currently have. SPL in not that important, as long as I can hit 115 db at 20 or 17 Hz. The second goal is to increase TR because that is really what we are after in the HT. The UM 18 and SI 18 HT like big boxes. The large sealed boxes will need less power, dig deeper, and have a bigger mid bass punch. By Monday I will make up my mind on going sealed or ported. The ported box in the pic is tuned to 15 Hz. 115 db at 17-20 HZ? You do need to warn the seismologists of the upcoming event LOL Mark Quote Link to comment Share on other sites More sharing options...
jason str Posted June 13, 2016 Share Posted June 13, 2016 I would recommend using a round port flared on both sides rather than a slot port on a driver like that to reduce port chuffing under high excursion. Wrapping the port tubes in damping material would be another good addition. Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted June 13, 2016 Author Share Posted June 13, 2016 (edited) For the average home theater maybe a closed sub would make a difference....not in your though. The vented idea works great, and whether you use the DS4 or the UMAX18 I think the way to get something new and improved is to go with a box size you haven't had yet. A lot of the DS4 models seem to be shooting for around 20CFT, and the extension you would have that way, right behind the couch would give you the benefits of a closed sub with 4 drivers in it potentially. But opening the door on an even larger box may tempt you to change the others too... A 20 cu. ft. box is out of the question due to room aesthetics and it is just to big. I have heard an array of 4 Stonehammer subs, four, 20 cu ft. boxes stacked and it is potent beyond words. My pant legs were flapping from 20 ft. away. I would recommend using a round port flared on both sides rather than a slot port on a driver like that to reduce port chuffing under high excursion. The slot ports are good size and should do OK in the nearfield since they will be set lower than the farfield subs. I've not had and problems with cuffing from the Marty type subs which is 1 cu. ft. less. I am still on the fence on doing the BackBum Buster as a vented sub with one driver vs a sealed version with two divers. I also don't know how to do round ports yet, lol. Edited June 13, 2016 by derrickdj1 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted June 13, 2016 Author Share Posted June 13, 2016 I'm going to back track on the 20 cu ft. box. I have the perfect spot, furthest away from the MLP, approx. 26-28 ft. I will build the BackBum Buster and the 20 cu. ft After Shock sub! Time to get going! 1 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted June 15, 2016 Author Share Posted June 15, 2016 Well, I started the build on the 12 cu ft. sofa table style sub. Pic's of the progress in the AM. 1 Quote Link to comment Share on other sites More sharing options...
Shodrewken Posted June 15, 2016 Share Posted June 15, 2016 You're a deep bass machine bud! Looking forward to your pics! 1 Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted June 15, 2016 Share Posted June 15, 2016 Love the idea and the enthusiasm DJ. Can't wait to see these beasts ☺ Aftershock lol dwfinitwly the right name! Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 15, 2016 Share Posted June 15, 2016 Well, I started the build on the 12 cu ft. sofa table style sub. Pic's of the progress in the AM. THAT'S what you need. 1 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted June 15, 2016 Author Share Posted June 15, 2016 Last night, just time for the base and side. I had a good morning until the heat drove me indoors, lol. Hopefully later today or tomorrow I will cut the subwoofer opening and get the baffle and top onl I found a little bargin at Homedepot, a nice top piece. 2 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 15, 2016 Share Posted June 15, 2016 Sweeeeeeeeet! 1 Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted June 15, 2016 Share Posted June 15, 2016 DJ you got no fear making these things, they look great and professional. Good luck and please finish it within the next 10 days :) :) 1 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted June 16, 2016 Author Share Posted June 16, 2016 I'm hitting a slow spot. I have to make some pretty precise cuts around the slot port and all this needs to be in line with the subwoofer. Most slot ports go all the way across and it is a bit easier. I did get a good deal on the marble style counter top. Slightly damaged and good mark down on the tops. Some were $11 to 20 dollars. So, I grabbed one. Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted June 16, 2016 Share Posted June 16, 2016 Sweet. Marble top will look great. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 16, 2016 Share Posted June 16, 2016 Derrick, you should have invested in a track saw by now (I don't believe I've read where you have). Once you do, you'll kick yourself for not doing it sooner, I know I did. 1 Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted June 16, 2016 Share Posted June 16, 2016 .. Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted June 16, 2016 Share Posted June 16, 2016 Thanks Derrick. I realize my sub setup will have cost more than the rest of my system combined...but thats largely because i got great deals on each component. Coming to the realization that almost all subs at stores are not sufficient and one of any sub wont make a HT great is a process. Its been surprising and eye opening to realize just how difficult it is to fill a ht room with enough low end bass to really reproduce a movie properly. I told a friend I was selling my RSW and his reaction was "oh? Was it overkill in your room?" shows just how far ive come in 6 months. Full Bass Addict 3 Quote Link to comment Share on other sites More sharing options...
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