D-MAN Posted October 7, 2004 Share Posted October 7, 2004 ---------------- On 10/6/2004 8:24:49 PM BEC wrote: D-MAN, I am sure the cabinet guy would provide them anyway anyone wants them. Since they are now in his CAD program that drives his CNC router, changes are easy and of course left flat for shipping would likely save a bit of money he charges for assembly. I should mention though that the guy can put that cabinet together so fast that he just looks like a blur to me, so, I doubt not being assembled would save much on his charge. Now, a question. I know that I need some padding on the inside of the bass box and I am looking for suggestions on easily available material for that. I wanted to do a bit of testing first to see what difference a lack of padding inside would have and have done that now. I have a peak at around 100 hz and a dip at around 300 hz. Other than those two points, the response is very flat down to around 30 hz. At that point it drops off smoothly at the rate of about 2 db per hz down to 27 hz which is as low as I attempted to measure. I have seen that something called "open cell" foam seems to be the thing to use for the padding but have not found any foam locally that calls itself "open cell". Some seem to use the "egg crate" foam and that stuff looks like it would be good but again, they want it to be "open cell". Any suggestions? Bob ---------------- Bob, I stayed with the traditional standby: fiberglass. Slightly messy but easily controllable in both depth and volume. I have not experimented with the others, but my KEF's have that foam stuff in them, too. I believe that that is used for its ease in manufacture, and that it can easily be glued in place. DM Quote Link to comment Share on other sites More sharing options...
BEC Posted October 7, 2004 Author Share Posted October 7, 2004 ---------------- On 10/7/2004 10:22:04 AM Frzninvt wrote: Here is what I used. http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-516 I attached it with Scotch 77 Spray Adhesive after cutting the pieces to fit in the cabinet. It did made a difference in the smoothness of the bass response in the '86 Cornwall II and removed any cabinet resonances. ---------------- I did see the material that Parts Express has and I guess I should have been clearer. I am sure that someone cuts the pieces that PE sells from larger sheets. By the time one pays PE for enough of that stuff to line the insides of the bass boxes, and pays shipping on that amount, it get somewhat expensive. More money for the foam than for the MDF to build the boxes. I am trying to avoid the fiberglass mess but expect that (except for the mess) it is close to ideal. Bob Crites Quote Link to comment Share on other sites More sharing options...
Dflip Posted October 8, 2004 Share Posted October 8, 2004 These guys make two inch thick egg crate style acoustical foam. Not sure if it is what you are thinking about or not, but the price is not too bad and can be custom cut for you. Don http://www.foamorder.com/acoustic.html Quote Link to comment Share on other sites More sharing options...
BEC Posted October 21, 2004 Author Share Posted October 21, 2004 Well, I got the second cabinet from the cabinet shop. Soon to have 2-channel driver test boxes. Bob Crites Quote Link to comment Share on other sites More sharing options...
D-MAN Posted October 21, 2004 Share Posted October 21, 2004 Sweet! Are you going to paint them or anything? Not that it matters for testing purposes, but those are so darn nice... DM Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted October 21, 2004 Share Posted October 21, 2004 Bob, is the cut for the woofer beveled? Are you also considering doing 12' drivers? I may have another donor. Regards, Terry Quote Link to comment Share on other sites More sharing options...
BEC Posted October 21, 2004 Author Share Posted October 21, 2004 D-MAN, At least until I get through all the testing and trying things in them they will just stay unfinished. Really just want to get the sound totally sorted out now. So far, I have only listened to one of the new boxes with a Lascala for the other channel. The way that works out is the the Lascala overpowers the new box on the mids and highs and the new box seriously out performs the Lascala on the low end. I need two of the boxes working to really judge the sound. Bob Quote Link to comment Share on other sites More sharing options...
BEC Posted October 21, 2004 Author Share Posted October 21, 2004 Terry, The woofer cutout is milled to allow the woofer to recess 1/4 inch into the front of the cabinet. That is just to make mounting from the front easier for a quick change out of woofers. If I were building them for just listening, I think I would just have the it cut for mounting the woofer from the inside of the motor board. That would look better and leave a grill as a possibility. I haven't looked into doing the 12 inch thing on woofers yet. Not sure that there is a recone kit for those. Bob Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted October 21, 2004 Share Posted October 21, 2004 ..........." the new box seriously out performs the Lascala on the low end......" Bob, I am so glad that you said that and I did not. I have believed as much for years. Do you have the new boxes crossed over at 400hz? Is the mid and top end attenuated? Regards, Terry Quote Link to comment Share on other sites More sharing options...
BEC Posted October 21, 2004 Author Share Posted October 21, 2004 Terry, It is like a Cornwall with the mid-horn of the Lascala or Khorn. Yes, the tweeter and mid-horn are attenuated like the Cornwall to match the woofer. The crossover is at 400 hz. I will do more testing soon on the pair and post some results. I have to get some padding in both bass cabinets and do a few other things to them and get down to some serious listening and testing to see if I have everything right. I like what I hear so far. Your old K-33 is performing admirably in the first cabinet now. Bob Quote Link to comment Share on other sites More sharing options...
IndyKlipschFan Posted October 22, 2004 Share Posted October 22, 2004 3 tweeters?? I may add.. maybe it is me, but a very clean pair of birch raw speakers like the la scalas... never finished in the new wood look.. to me.. I love. I passed on a pair a few years ago for 700 for the pair.. a 10- 10. I wish I had not have. Quote Link to comment Share on other sites More sharing options...
BEC Posted October 22, 2004 Author Share Posted October 22, 2004 Remember that I am building these as driver test boxes. The provision for 3 tweeters to be installed in one of the boxes is for tweeter comparison and testing. For instance, when I rebuild a pair of tweeters the rebuilt ones can be compared to a "standard" tweeter and to each other by use of switches to select one at a time. I have already been using a similar arrangement that sits on top of one of my Lascalas. This replaces that crude tweeter test fixture. Bob Crites Quote Link to comment Share on other sites More sharing options...
BEC Posted October 23, 2004 Author Share Posted October 23, 2004 Ok, back to work on the second cabinet today. I decided to try cheap foam carpet pad on the inside of the bass cabinet. This is $15.00 worth of foam carpet pad, a hot glue gun and scissors. I will leave the first box not padded to see the difference in sound. If I like this stuff, I will do the other box in it. If not, will try something else. Bob Crites Quote Link to comment Share on other sites More sharing options...
BEC Posted October 23, 2004 Author Share Posted October 23, 2004 Tweeter installation is with drive-in inserts using studs threaded into the inserts and wing nuts to attach. That would be for the ability to change them out quickly on this test box. Bob Crites Quote Link to comment Share on other sites More sharing options...
BEC Posted October 23, 2004 Author Share Posted October 23, 2004 If you have been following this thread, you may remember that I have been trying to figure out a quick way to mount the woofer from the front. Here is what I have worked out to try. There are 4 10-32 drive in inserts installed from the front. The hole for the inserts extends all the way through the motor board so that 10-32 X 2 inch screws can be installed from the back through the inserts. Then some metal plates are installed and held in place with wing nuts. The strap across the bottom of the woofer gives a lip to hold the woofer in place until the wing nuts are tightened. I still have to get some small springs to go under the 4 metal plates that will hold them forward against the wing nuts to position them out of the way (turned sideways) to ease installation. Bob Crites Quote Link to comment Share on other sites More sharing options...
psg Posted October 23, 2004 Share Posted October 23, 2004 If you have been following this thread, you may remember that I have been trying to figure out a quick way to mount the woofer from the front. Here is what I have worked out to try. There are 4 10-32 drive in inserts installed from the front. The hole for the inserts extends all the way through the motor board so that 10-32 X 2 inch screws can be installed from the back through the inserts. Then some metal plates are installed and held in place with wing nuts. The strap across the bottom of the woofer gives a lip to hold the woofer in place until the wing nuts are tightened. I still have to get some small springs to go under the 4 metal plates that will hold them forward against the wing nuts to position them out of the way (turned sideways) to ease installation. Bob, there was a subwoofer thread recently in which a URL was provided to a sub built under the HT room (in the basement). The sub consisted of many 15" woofers and they were held in the hole using a similar arrangement, but using C-shape d pipe holders. I should find the link because my explaination sucks. But I think it would work. Peter Quote Link to comment Share on other sites More sharing options...
psg Posted October 23, 2004 Share Posted October 23, 2004 Found it! See http://home.comcast.net/~klone-audio/page13-12Shiva1.html Sorry I didn't think to tell you either. I just now made the connection that you needed something like this. Quote Link to comment Share on other sites More sharing options...
BEC Posted October 23, 2004 Author Share Posted October 23, 2004 Peter, I had seen that link before. I think it is somewhere earlier in this thread. Since I am having to clamp the woofer from the front, I think the flat plates I decided on may be a bit nicer to the thick gasket than the pipe clamp idea. To mount them from the back side like those in the link, I think the pipe clamps would be best. Bob Crites Quote Link to comment Share on other sites More sharing options...
psg Posted October 23, 2004 Share Posted October 23, 2004 Sorry... And I thought I was on to something. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted October 24, 2004 Share Posted October 24, 2004 Bob: I've just now found this while directing another post about a blown K-horn tweeter your way. This box looks really outstanding! What a great idea! Erik Quote Link to comment Share on other sites More sharing options...
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