DrWho Posted July 20, 2006 Share Posted July 20, 2006 I've been thinking about this for a while and figured I'd share a few ideas on the forum. The idea is spurred specifically by the demo of the Jubilee in Hope. It just didn't have enough bass. Am I a bass freak? Perhaps. But some of my favorite music doesn't sound right on every hornloaded bassbin I've heard. Is this a function of how these horns distort with information below their cutoff, or just the mere lack of LF information due to the steeper roll offs? Well why not build a bass horn that digs below the cutoff of my music and then see if I don't like? [] To my knowledge I know of no other subwoofer system that performs this way, but like any idea I'm sure somebody has already come up with it. Anyways, when playing around with horn modelling software I've noticed that you get a lot of peaks and dips when you make the mouth too small and the horn too short for the desired cutoff. And it seems like such a waste to use only half the power generated by the driver. I haven't yet drawn up a plan, but here's a rough sketch of the idea behind the layout. Both the front and rear wave of the driver will be hornloaded and will towards the end of their expansion share the same mouth. The stuff in red is protruding out of the page and is where the two wavefronts should meet again. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2006 Author Share Posted July 20, 2006 But you might say to yourself, but the rear and front wave from the driver will be of opposite polarity. I know this is just a basic modelling program, but I can't help but think there is some truth behind the phase data in these charts. What we have here is the SPL response for two horns. The darker being a 2 square foot mouth with a length of 4meters and the lighter being the same mouth with a length of 6meters: Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2006 Author Share Posted July 20, 2006 And then finally, the phase response of each system: Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2006 Author Share Posted July 20, 2006 So if you go ahead and add the two frequency response plots together in your head while taking into account a polarity reversal on the model we should get a relatively flat response from 16Hz up to 80Hz...perhaps slightly less output down low, but that would be reinforced by the room gain that the subwoofer ends up in. Another idea that has crossed my mind is to use a pair of drivers firing away from each other, but sharing the same cabinet in the middle and then porting the system to extend the output even lower. I'm not sure if the ports should fire into the same horn channel as the drivers or perhaps come out of the side and directly into the mouth where all the wavefronts combine. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 20, 2006 Share Posted July 20, 2006 DrWho This is a good idea. Something to think about. Instead of trying to horn load the back of a woofer, put the woofer in a box, horn load the front as normal, put a passive radiator or a push-pull woofer in the box opposite the first, and horn load that as well. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2006 Author Share Posted July 20, 2006 Now that's an interesting idea...and would get rid of comb-filtering problems up higher in the pass band as well. It would also be cheaper than running two active drivers as well. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2006 Author Share Posted July 20, 2006 So anyways, the goal was to come up with a hornloaded bass bin that would be feasible to implement in the home...with a 4m and a 6m bent horn coming together this isn't exactly small [] The idea behind the shape was to make it feasible to fit behind a 3 foot false wall and have the mouth in from the sides to allow for corner placement of the mains. I'm not sure if the math works out to make such a goal possible, but there does some to be some flexibility with the numbers. For what it's worth, here is the input information: Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2006 Author Share Posted July 20, 2006 One thing that has crossed my mind is how the Danley DTS-20 achieves such insane performance in an even smaller package. And apparently Tom talks about the concept behind the "tapped horn" in this pdf: http://www.danleysoundlabs.com/pdf/danley_tapped.pdf hmmm, I wonder if it's the same concept? Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 21, 2006 Share Posted July 21, 2006 intresting PDF, will read it in the AM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted July 21, 2006 Share Posted July 21, 2006 Not to take anything away from Tom Danley, but the so-called "tapped horn" idea has been around for quite awhile... like the proverb I'm fond of saying, "there is nothing new under the sun", horn-wise, that is... He had to know about this Electro-Voice patent, I would think... I wonder what is different enough to patent? Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 21, 2006 Author Share Posted July 21, 2006 Perhaps the use of only one driver? Or having it enter somewhere inside the mouth of the horn? Quote Link to comment Share on other sites More sharing options...
D-MAN Posted July 21, 2006 Share Posted July 21, 2006 I have yet to figure out when something is different enough to warrant a patent! Wayne Parham has a new dual 12" PP sub that would be worth looking at. He says some interesting things about how it tests and the push-pull effect. Here's the thread: http://audioroundtable.com/PiSpeakers/messages/17536.html DM Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted July 21, 2006 Share Posted July 21, 2006 Here's an interesting diy sub solution to 18hz by Roy Delgado. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=018&item=280008268599&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1 Quote Link to comment Share on other sites More sharing options...
jorjen Posted July 21, 2006 Share Posted July 21, 2006 Wow! I bet the wife could toss out the blow dryer with that in the house. [] Awesome looking sub. And to 18hz, oh my! Dana, Looks like Mr. Parham has made some progress on construction since the last time I checked for pics. Appears to be a somewhat complex build, but I would sure like to hear the results. Looks very cool. By the way, are you planning on constructing a pair of your Ascent with the new addition to the throat? Or, have you already? If so, what are your findings? No hijack intended Mike. Quote Link to comment Share on other sites More sharing options...
D-MAN Posted July 21, 2006 Share Posted July 21, 2006 It's always good to look at other's work out there, and hopefully glean some useful information. Push-Pull configuration is not something I know alot about, but from what I've read so far, it could be very cool on a subwoofer; i.e., the "next big thing", or at least, certainly another tool in the kit. Especially for HORN subs, a somewhat rare commodity. So Dad-D, Roy is making subs? That's his? Cool. Jordan, not yet. But I will eventually! I was hoping that you'd give it a rip and tell me! Dana Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted July 21, 2006 Share Posted July 21, 2006 Another forum member mentioned the auction, so I don't know what he would or would not have in the works. I thought it looked very cool though, and would be killer. Size though, it's a big rascal and actually would be quite good, I'd think, in a theatre setting. If someone had the space in a HT room or even with two channel, wowweeee. Talking about moving some serious air. Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted July 21, 2006 Share Posted July 21, 2006 uh guys....not my puppy. this was given to me to play with by a theater friend of mine. he really liked it and i asked him if he wanted a klipsch solution. solution? the kpt-884..... a guy out there make these subs and sells them to theater guys. it sounds very very good. it uses the aura 18 that my ex jbl buddy of mine designed for aura. he sent me a proto woofer in the early nineties to play with and i thought this woofer was the mother of all woofers. he did a great job on the design. by the way, hornloading a vented sub....hmmm, why didn't i think of that...... roy Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted July 22, 2006 Share Posted July 22, 2006 oops. Thanks for the clarification. I apologize for passing along incorrect info. [:$] Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 22, 2006 Share Posted July 22, 2006 That e-bay sub has no tech info. Guessing it looks 4ft wide, 2 ft high. Not sure what is coming out of those vents. I don't think it would qualify as horn loaded. The lisitng needs more tech info with operating theroy, performance expectations, or needs ot cite what legacy design it emulates (EV, Atlas, etc). Quote Link to comment Share on other sites More sharing options...
sunnysal Posted July 22, 2006 Share Posted July 22, 2006 dr. who, when you get a chance post some drawings of you idea. it certainly sounds interesting. The back wave length to to assure in phase relationship with front wave at exit should be easy to implement. tony Quote Link to comment Share on other sites More sharing options...
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