Rudy81 Posted December 6, 2010 Share Posted December 6, 2010 I have finally settled on a design for my DIY sub to replace my SVS 20-39 PC+. I figured I'd post the details here for the experts to look at before I trash four sheets of 18mm BB. Please let me know if you see any major problems with the design. I have been contemplating various DIY subs, including IB, SPUD, and Tuba HT. For various reasons I decided to go with an 18" driver (Maelstrom) ported enclosure. The box will be tuned to 15Hz and has a net volume of 15 cu. ft. Size will be 42"Hx31"Wx28"D. Here is a little diagram. Yes, I know the bracing shouldn't be solid....I just can't get Google Sketchup to let me cut holes in the braces. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 6, 2010 Author Share Posted December 6, 2010 This is SPL WinISD plot at 500 watts. I'm sure that sub will more than shake the house. BTW, here is a link to the driver: http://www.diycable.com/main/product_info.php?products_id=681 Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 6, 2010 Author Share Posted December 6, 2010 Here's the port air velocity at the same power. First port resonance will be above 240Hz, so the port should not present any problems. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted December 7, 2010 Share Posted December 7, 2010 It looks great to me but you might want to PM Michael Hurd and link him to this post. He's really good with winisd and DIY cabinets in general. If he says it's OK, I'd run with it. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted December 7, 2010 Share Posted December 7, 2010 Is the front baffle double ply? I can't tell from the drawing.. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 Oh yes, the baffle will be double ply. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 I am considering going with two Mach 5 IXL drivers vs. a single Maelstrom....price would be the same. Performance would be slightly better with dual drivers. I am planning on using a Crown XLS 802 to driver the sub....either bridged for one driver or two channel for dual drivers via a DCX 2496. Here are the models. BTW this is simulating 1000W. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 Air Velocity prediction Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 Cone excursion Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 Impedance. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 OTOH, the more I read on the subject, the more I realize there is not much to be gained by adding a second driver the box. I might just stick a single 18" Mach 5 driver. http://www.mach5audio.com/zen/index.php?main_page=product_info&cPath=65&products_id=181&zenid=2c574ca7a2e3a34c67c70ed442da9c96 Performance will be a little less than the Maelstrom, but at half the price.... Quote Link to comment Share on other sites More sharing options...
michael hurd Posted December 7, 2010 Share Posted December 7, 2010 Rudy: first of very nice room! I'd like to ask you first what your goals are before deciding on an end point, your desired output level @ what frequency. Are you going to be using this subwoofer for LFE effects in movies, or simply music>? If you try to run it in conjunction with other subwoofers that have varying phase responses, you will most likely have some cancellations. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 Mike: This build is for LFE on movies exclusively. My current dual RSW-15's are 'part of' my DBB's. No other subs will be in play since I am replacing my SVS with the build. Goal is to have a solid sub that can handle what Blu Ray audio is sending to the LFE channel. SPL will be nowhere near what that driver can do. We watch movies at near 'refernce' for Audyssey, which is around 75dB. I'm sure dynamics gets up well past, but that is the goal. This project started because I am getting amazing musical bass performance from my DBB and RSW-15 combination for 2 channel. However, duing movies, the SVS 20-39 PC+ is not enough in a 5000 cu. ft. room. I looked around for an Epik Conquest or similar but no luck. I have been looking for over a year. Since I enjoyed the DBB build, I figured why not do a sub build. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 BTW Mike, do you recommend round ports or slots.....or some other variation in a design such as this? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted December 7, 2010 Share Posted December 7, 2010 BTW Mike, do you recommend round ports or slots.....or some other variation in a design such as this? He used passive radiators in his last build. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted December 7, 2010 Share Posted December 7, 2010 BTW Mike, do you recommend round ports or slots.....or some other variation in a design such as this? Round ports offer less frictional surface area vs a slot port of equivalent tuning. GIven the choice, if you can fit a round straight port with roundovers and an inside flange, that would be my preferred choice. What is your budget? There is nothing wrong with the Maelstrom at all, it is a decent driver offering good performance. I would suggest also looking alternately at a pair of Acoustic Elegance AV-15X's, once John gets surrounds produced in house. ( his supplier was not going to produce any more loudspeaker parts ) The lead time will be longer on the AE product, but a pair has a few advantages to a single 18" driver. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted December 7, 2010 Share Posted December 7, 2010 It appears that you are around ~ 12-14 ft or thereabouts back from your screen. ( main seating ) If you want to be able to hit reference levels @ the seats, you need 115 db peak ( at the seating location ) from the LFE channel as compared to 105 for each other channel. I didn't have the new Gen II Maelstrom specs in WinISD... so this model is with the older Gen I specs. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 I suspect I will not be able to use a straight round port to have a 15Hz tune. It will likely be a pair with a bend in them. Decisions, decisions. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 OTOH, I can just change the design to place the port along the long side of the enclosure. I guess it doesn't matter where the port exits.....does it? Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted December 7, 2010 Author Share Posted December 7, 2010 BTW, many driver files can be found here: http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/14410-downloadable-winisd-pro-files.html Quote Link to comment Share on other sites More sharing options...
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