dkalsi Posted July 16, 2008 Share Posted July 16, 2008 I feel like constructing a speaker. I've really enjoyed JC forum on the Conwall DBB - what awesome looking (and probably even better sounding) speaker. I have to following parts on hand: Altec 511B horns, JBL 2404H tweeters, and K-55 drivers. I, like JC, love the bass on the Cornwalls and want to create something similar to the Cornwall DBB but on a budget. I wanted to know if it would be a good idea to construct something like the JBL 4435 It would be nice to create something that looks similar to the picture of 4435 above. Where there is two 15" woofer in the lower half and an Altec 511B+JBL 2404 on top. Is this a good idea to create a system with side by side woofers like this (i was reading JC Cornwall DBB forum and Dr.Who and DeanG advised against having horizontal orientation for the woofers). I am open to using a single woofer as well --, but because I would like more bass, is it possible for me to use a 18" woofer? I am just hoping some experts may chime in and suggest what I could possible build given the components l listed above. Thanks Quote Link to comment Share on other sites More sharing options...
djk Posted July 17, 2008 Share Posted July 17, 2008 Only one woofer in the 4435 runs up to the midrange crossover point, the other is rolled-off above 100hz. http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4435LR.pdf Quote Link to comment Share on other sites More sharing options...
dkalsi Posted July 17, 2008 Author Share Posted July 17, 2008 Thanks for that djk, I think this idea was also suggested in JC ConrwallDBB forum. However, he wanted both woofers to work together to increase db. Would it be a better to use a sigle woofer (maybe 18") woofer? Or could I still use the design above and not seperate the frequencies they will play? Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 17, 2008 Share Posted July 17, 2008 To make more clear what DJK is saying, both woofers operate together down low... and one is rolled off, leaving one out to the crossover point. This is like the tapered array in the RC3II center, the RC7 center etc. Same idea. Also called a 2.5 way crossover. Quote Link to comment Share on other sites More sharing options...
dkalsi Posted July 17, 2008 Author Share Posted July 17, 2008 I am just curious how much of an improvement in overall sound is there when utilizing two subs down low. Would it be better to create a system simlar to the JBLs (and having one sub rolloff say around a 100hz) or is it better to just utilized one 18" that will have sufficient output in the lower frequencies. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 17, 2008 Share Posted July 17, 2008 I would think that a single 18 would be troublesome to cross to a midrange horn, hard to say. Quote Link to comment Share on other sites More sharing options...
capo72 Posted July 18, 2008 Share Posted July 18, 2008 Michael raises an important point. There are plenty of drivers out there that will provide adequate low end performance, the problem is going to be finding one that has usable response up high to cross over to your 500 hz mid horn/ K-55 and porvide house shaking bottom end. It's all about compromises when trying to design your own speaker. I've had an ongoing DIY project for a while now and I still don't have it all figured out. I'm am using a single 18" as you mentioned above. I'm using JBL 2245 18" drivers which JBL says can be crossed over up to 800 hz, but most on the Lansing Heritage forums say they are only good up to 300-400 hz depending on the enclosure. I hope to be crossing over somewhere in that range to my JBL 2482 midrange driver mounted on my DIY 225 hz Tractrix horn. The 2482's have a frequency response from around 300-5000 hz. I then plan to crossover around 4500 hz to a pair of Bob Crites CT-125 tweeters. It's difficult to find drivers to give flat response across the entire spectrum in a 2-way or 3-way set-up. You may have noticed many of JBL's speakers are 4-way. The more drivers you ad into the mix the more difficult it becomes for the home builder to design passive networks. Maybe you plan to tri-amp or quad-amp with active crossovers. Once I get my bass cabinets complete and everything assembled, I plan to do frequency response tests on each individual driver in assembly to see what kind of actual response i'm getting from each driver before I decide where to put the crossover points. This may prove to be more difficult than it sounds. I just want to point out that alot of thought needs to go into a home brew project, unless you prefer to emulate a project that someone has already proven out like the DBB Cornscala. Just remember that the journey may be more important as the destination. Good luck, Jeremy Quote Link to comment Share on other sites More sharing options...
djk Posted July 18, 2008 Share Posted July 18, 2008 The more efficient a direct radiator is, the less bass it has. The No% (efficiency) of a direct radiator is only applicable in the octave between the EBP frequency and the mass corner frequency (one octave higher). For the JBL drivers shown that is 101dB, 97dB, and 93dB. The 2234 (used in the 4435) is 2dB more efficient than the 2235 shown in these graphs. The idea is to have the second woofer come in at the EBP corner to extend the bass without messing up the midrange. Most 18s do not sound good above 300hz (there are expensive exceptions), and being around 97dB they will look quite similar to the middle curve above. Quote Link to comment Share on other sites More sharing options...
djk Posted July 18, 2008 Share Posted July 18, 2008 Here is a double 15 design that works well to 500hz with the drivers stacked vertically. The sensitivity is about 102dB/2.83V/1M and is a minimum of a 4 ohm load (as opposed to two K33 drop to 2 ohms minimum). These drivers were originally designed for a Yamaha pro sound subwoofer and have a rubber surround. Note the small box size (8 cu ft for both), not much bigger than a Cornwall. A high-pass filter (included in the response curve shown) at 31hz is recommended, especially if using a phono and/or high power. Quote Link to comment Share on other sites More sharing options...
dkalsi Posted July 18, 2008 Author Share Posted July 18, 2008 DJK, What is the exact model of the drivers. I am open to driver selection as I have not purchased anything. The one problem is that I would like to orient the woofers horizontally. Having them vertically would make the speaker to tall for my liking (as was the issue the JC was having) unless I was to go with the same exact corner design JC created for the Cornwall DBB. I guess if I was to go with the side by side design, it might be a good idea cross one woofer at 100hz and allow the other to play up to 500hz. I would imagine a sigle 15" woofer could easily play between 100hz-500hz. Its the bass impact below 100hz where the second woofer would help significantly. But this raises another problem - the crossover - it would be incredible difficult to build. Please continue to share your thoughts. Quote Link to comment Share on other sites More sharing options...
djk Posted July 19, 2008 Share Posted July 19, 2008 view pdf 15269 / CAT NO - 1844 • santoprene rubber surround • extra thick treated paper cone • diameter: 15.187" • impedance: 8 Ω • ...more info PRICE : $ 103.99/ea. QTY. You may have to have either Bob Crites or myself order them for you, they have a high minimum order. Quote Link to comment Share on other sites More sharing options...
djk Posted July 19, 2008 Share Posted July 19, 2008 Best method http://www.pioneerelectronics.com/PUSA/Products/BusinessProducts/ProfessionalSpeakers/ci.TCM-1621%7C1622.Popup Alternate method (angled across each other) http://www.tadhomeaudio.com/sitebuilder/images/studio_2_s-204x190.jpg http://www.tannoy-speakers.com/products/303/large-3q-grill-off.jpg http://www.tannoy-speakers.com/products/303/large-front-grill-off.jpg http://www.tannoy-speakers.com/products/308/large-front-grill-off.jpg Works (last choice) http://www.pioneerelectronics.com/PUSA/Products/BusinessProducts/ProfessionalSpeakers/MODEL+2401 Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 19, 2008 Share Posted July 19, 2008 " advised against having horizontal orientation for the woofers" it depends on the cross over frequency and the slopes of the xovers. 500hz and below is not an issue as humans are less sensitive to all the audio nuisance classifications that exist if they occur below 500hz The slopes of the xovers are a factor to consider.....gentle slope xovers mean that your woofs would carry upper octave mid range as a result of the gradual roll off nature of gentle slope xovers. Quote Link to comment Share on other sites More sharing options...
dkalsi Posted July 20, 2008 Author Share Posted July 20, 2008 DJK, I someone was to help me with the design, I'd be happy to try any of the orientations you listed. Could you also explain why your last choice was your last choice? Thanks D Quote Link to comment Share on other sites More sharing options...
djk Posted July 20, 2008 Share Posted July 20, 2008 Because it doesn't sound as good as the other methods. I've done it that way on purpose in a church install with dual 12s. Hoisted up near the ceiling it has narrow enough horizontal pattern to reach the balcony without a lot of splash off the side walls, and wide enough vertical dispersion to cover the main floor. At home the reverse works better. The angle method reduces comb-filtering and boadens dispersion in the horizontal plane. The Tannoy has a bit of a cavity with some ramps that limit the vertical dispersion and reduce early reflections in the crossover region. The flat method works, Westlake still sells its TM-3 reference series monitor, but I think it's worth the effort to angle them. Quote Link to comment Share on other sites More sharing options...
dkalsi Posted July 20, 2008 Author Share Posted July 20, 2008 DJK, If you think its worth the effort, then that is definitely the route I will take. Would it be possible to design something like that using the yamaha woofers you listed above? I love the fact that the combined volume woud not be significantly bigger than a single cornwall. Is there any already established angle designs out there that I maybe able to use. The thing is that I wouldn't have a clue how to desgin something like that. If there are plans already out there and I just have to make the cuts, that would be awesome. Quote Link to comment Share on other sites More sharing options...
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