Rudy81 Posted May 29, 2011 Share Posted May 29, 2011 Guys, I'm planning on a DIY center channel build in the near future. It will be a two way speaker, actively crossed with dual 15" Kappalite Neo woofers. My plan is to use the 3/4" high density MDF I have left from my DIY horn build, beefed up as required with 18mm BB. I plan on building the woofer box individually and then making a separate HF horn enclosure to sit on top of the woofer box. Reason is that I want the ability to change out horns if desired at a later date. First question that comes to mind concerns the enclosure design. Does it matter if the drivers are in their own enclosure, such as JC's DBB, or can both woofers perform just as well in one enclosure? For example, one 10 cu. ft. enclosure vs. two 5 cu. ft. enclosures built together. I'm using WINisd to configure the size and ports. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 22, 2011 Author Share Posted June 22, 2011 No takers on my first post, so I just dove in. Here is the basic setup, dual 15" Kappalite Neo woofers, four ports. I expect to tune it somewhere between 40-45Hz. The reason for the odd shape is I will have it sit on top of my tapped horn subs and I need just enough room under my screen for the HF horn. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 22, 2011 Author Share Posted June 22, 2011 This has been my first venture into using MDF for a speaker build....it will be my last. I hate using this stuff. Very susceptible to damage, can't hold screws...etc. I had some MDF, high quality I might add, from my tractrix horn build and decided to use it for the enclosure. I should have used BB like I did form DBBs. Too late now, so I hope it will work ok. I beefed up the motorboard with a 1/2" BB plywood, glued and screwed, to give the woofer screws something to bite into. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 22, 2011 Author Share Posted June 22, 2011 Plenty of bracing to ensure I have a stiff box for the dual woofers. More to come next week when I can work on this again. Quote Link to comment Share on other sites More sharing options...
jbsl Posted June 22, 2011 Share Posted June 22, 2011 looking very nice! [] Quote Link to comment Share on other sites More sharing options...
mustang guy Posted June 22, 2011 Share Posted June 22, 2011 No advise, just wanted to commend you on a great project idea. I was thinking about doing something like that, but decided on a LaScala. I may end up some day splitting the LaScala like other have and put the bass cab under with the horn/tweet over the screen. That thing you are building should rock! Quote Link to comment Share on other sites More sharing options...
Ironsave Posted June 22, 2011 Share Posted June 22, 2011 No takers on my first post, so I just dove in. Rudy, I had nothing I could give regarding advice. Looks good so far..... Will be watching........ Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 24, 2011 Author Share Posted June 24, 2011 Thanks guys. I plan on finishing this build next week. I will be posting performance sweeps etc. Quote Link to comment Share on other sites More sharing options...
Moderators dtel Posted June 25, 2011 Moderators Share Posted June 25, 2011 Your right screws suck in MDF but glue holds like a weld, very strong. When using MD I usually just shoot small finishing nails just to hold it together and clamped until the glue dries. Looks good, I don't think the same cabinet would matter unless the two drivers were given different signals like some center channels, as one would act almost as a midrange and the other bass. ? Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 25, 2011 Author Share Posted June 25, 2011 In this configuration both drivers must be sent the same signal. Yep, during this build I have learned to truly hate MDF. It may be more dense than BB, but it sure is much more difficult to work with and seems much less durable than plywood. Quote Link to comment Share on other sites More sharing options...
Arash Posted June 25, 2011 Share Posted June 25, 2011 a question: how do you connect two woofers to a crossover? serial? parallel?or crossover has two output just wanted to know bcuz I'm about to diy a center Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 25, 2011 Author Share Posted June 25, 2011 a question: how do you connect two woofers to a crossover? serial? parallel?or crossover has two output just wanted to know bcuz I'm about to diy a center In my case, I connect the woofers directly to my amp since I am using an active crossover. If you are using a passive, you will need to determine what impedance the crossover can handle....I believe. Basic series or parallel will produce a change in impedance you will have to take into consideration. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 27, 2011 Share Posted June 27, 2011 I normally use t-nuts with MDF. They're very effective, especially if you want to experiment by swapping drivers. I kind of like MDF, but it IS messy when cutting or routing. Be sure to wear a mask. Looks great though! Will be staying tuned. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 27, 2011 Share Posted June 27, 2011 How high can those 15's effectively be crossed over? They seem awfully big for a center channel speaker. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 27, 2011 Author Share Posted June 27, 2011 They theoretically can go up to 1500Hz, although I don't plan on crossing anywhere close to that. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 27, 2011 Share Posted June 27, 2011 DUH, just re-read the first fost. I would have stayed away from seperate enclosures as you have done. Do you have any idea what horns and drivers you'll use? Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 27, 2011 Author Share Posted June 27, 2011 I am merely replacing the La Scala bass bin I have been using with something that better matches my taste and better matches JC's DBB bass bins, which have Kappalite 3015 LF's in them. I will continue using my P. Audio horn and driver (K69). Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 29, 2011 Author Share Posted June 29, 2011 While the paint dries, I took an impedance sweep of both drivers, wired together in parallel, as I plan to install them. Here are the free air results for the woofers. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 29, 2011 Share Posted June 29, 2011 OK, let's see if I get this. The drivers are wired for a 4 Ohm load (present a 3 Ohm load) and if the easiest load is at the drivers Fs then the Fs is around 47 Hz. What's the top (red) line represent? Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted June 29, 2011 Author Share Posted June 29, 2011 OK, let's see if I get this. The drivers are wired for a 4 Ohm load (present a 3 Ohm load) and if the easiest load is at the drivers Fs then the Fs is around 47 Hz. What's the top (red) line represent? That's the phase response and you can see the degrees on the right scale. Once the speakers are mounted, I will run the same sweep and I should get two peaks since it is a ported enclosure. From what I have been told, if there are any problems with air leaks or the enclosure itself, it should show up then. Quote Link to comment Share on other sites More sharing options...
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