BEC Posted October 24, 2004 Author Share Posted October 24, 2004 Well, both boxes are functioning now. Really sound great. I was impressed with the amount of bass out of one box and now with two, a fantastic amount of bass. I will be listening, measuring and tweaking for awhile. Bob Crites Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted October 25, 2004 Share Posted October 25, 2004 Bob: What are you using to absorb standing waves inside the box? Also, what driver is being used (maybe this info. is up above -- I haven't read through the entire thread. Erik Quote Link to comment Share on other sites More sharing options...
BEC Posted October 25, 2004 Author Share Posted October 25, 2004 Erik, One of the boxes has nothing inside for padding now and the other one has foam carpet pad. I want to do some testing to see how the carpet pad works and to see if something works better. The drivers are the full complement of a Khorn or Lascala. One of the purposes of the boxes is to be able to quickly change out a driver with one I have rebuilt as a check for proper function. All the drivers are easily accessable including the woofer. It takes me less than a minute to change out the K-33E. The crossover is that of a Cornwall (Type with one cap value change to cross over to the squawker at 400 hz. If you or someone else should want one or a pair of the boxes, The cabinet shop that built these can turn them out pretty easily since they have them in a CAD program. They just feed in a sheet of MDF or other 3/4 inch material to the CNC router and out the other side comes all the cut pieces. Bob Crites Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted October 25, 2004 Share Posted October 25, 2004 Interesting! I hope you continue to update this as you experiment. Cabinet stuffing is such an influential part of this process, and I have had good results, depending on the type of box alignment, with industrial insulation, natural fiber wool batting, polyfill, and carpet pad such as what you're using. Also, are you using any kind of bracing within the enclosure, itself? I would be really fun to try these sometime! Erik Quote Link to comment Share on other sites More sharing options...
BEC Posted October 25, 2004 Author Share Posted October 25, 2004 Erik, The box has no extra bracing. It is essentially a 2 ft cube that is glued and nailed. I haven't been able to to find anything causing vibration or resonance yet so that seems to be satisfactory. I played them for awhile at 113 db measured at 1 meter last night. Listened and felt around on them for any sign of any vibration and did not find any. Lots of testing left to do. Just have to find the time. Bob Crites Quote Link to comment Share on other sites More sharing options...
emmet2u Posted October 27, 2004 Share Posted October 27, 2004 OOOOOPS Quote Link to comment Share on other sites More sharing options...
emmet2u Posted October 27, 2004 Share Posted October 27, 2004 Bob, From what I can see you have a 2' cube, but I am wondering about the shelf. How deep is it, and how much is left open, and where? Also, wht is the size of the openings on the front? BTW, the Heresy's are sounding better every day. Quote Link to comment Share on other sites More sharing options...
BEC Posted October 27, 2004 Author Share Posted October 27, 2004 The shelf extends back 9 1/2 inches. The ports in the front are sized to give the same area as in a Cornwall. They are about 9 X 2 3/4 inches each. Bob Crites Quote Link to comment Share on other sites More sharing options...
emmet2u Posted October 27, 2004 Share Posted October 27, 2004 Thanks for the info Bob. I'm thinking about building a "shortwall". WAF is part of the reason. Quote Link to comment Share on other sites More sharing options...
BEC Posted November 16, 2004 Author Share Posted November 16, 2004 Bump Bob Quote Link to comment Share on other sites More sharing options...
mike stehr Posted November 17, 2004 Share Posted November 17, 2004 When you say two foot cube, you aren't refering to internal volume? Isn't the typical cornwall cabinet around 6 cubic feet internal volume? What would be the internal volume of your K-33 bass enclosure that you are using? Have you tried blocking the ports somewhat (with wood or books or whatever) to see what happens? I think polyfil has a resistive kind of damping to it, it can be used to make the enclosure seem larger to the driver, something to that degree. I think a half pound of polyfil per foot of internal volume? I'm using a pair of '85 vintage Fostex 15" alnico woofers in my Cornwalls. The K-33 is a fine woofer, but the Fostex is....I dunno, I prefer it tonewise. With the Fostex's in the Cornwall cabinets, the port tuning frequency comes in at about 35, 36 Hz. I think that's around a stock Cornwall roll-off. The Fostex and K-33 (Eminence?) have pretty close Fs, the Fostex maybe a wee bit higher. With a audio generator through a power amp, there is a bit of a peak at 70, 80 Hz. But I think it's room induced. I still need to check it over again, maybe try some polyfil, blocking the ports, etc... A stiffer back panel and cabinet bracing would be a big bonus sonics wise, IMO. I dunno if it would depreciate the value of a stock Cornwall, however. Quote Link to comment Share on other sites More sharing options...
BEC Posted November 17, 2004 Author Share Posted November 17, 2004 Mike, The external size is a 2' cube. That gives an internal of about 22.5 X 22.5 X 22.5. This comes to slightly over the measured internal volume of a Cornwall. I made it slightly oversize on purpose since during tuning, I can easily decrease the volume if it helps to do so. Bob Crites Quote Link to comment Share on other sites More sharing options...
3dzapper Posted November 17, 2004 Share Posted November 17, 2004 In a letter to one Art Kulek in 1989 PWK wrote: "Your comments on the Cornwall® were interesting. The developemnet was 'cut and try', based first on a slot-in-the-back and then a port in the front. Dick Moore, a former employee, examined the Theil Equations (became available about 1975) and told me I had missed the optimum design by about 3%." Your La Wall sounds about in the same neiborhood Bob. I would love to build a pair with the top in a box, adjustable for toe in/out. I was thinking about a T-nuts in the bottom section with a threaded rod through an arced slot in the top fastened with a washer and a wing nut. Rick Quote Link to comment Share on other sites More sharing options...
mike stehr Posted November 17, 2004 Share Posted November 17, 2004 "Dick Moore, a former employee, examined the Theil Equations (became available about 1975) and told me I had missed the optimum design by about 3%." That wouldn't be too bad considering the Cornwall was conceived way before the days of Theil/Small, would it? Quote Link to comment Share on other sites More sharing options...
BEC Posted November 17, 2004 Author Share Posted November 17, 2004 Your La Wall sounds about in the same neiborhood Bob. I would love to build a pair with the top in a box, adjustable for toe in/out. I was thinking about a T-nuts in the bottom section with a threaded rod through an arced slot in the top fastened with a washer and a wing nut. Rick ---------------- Rick, Sounds good. Since these were ment to be used for driver testing, easy access to the drivers was my primary concern. The design can easily be modified to enclose the top end and your toe in/toe out adjustment sounds like a winning idea. You can make the woofer installation much easier by mounting from the back of the motor board. Again, I wanted woofer access from the front. Bob Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted November 18, 2004 Share Posted November 18, 2004 Bob, I've been looking over your pics again. The depth of the cab looks just long enough to accomodate the K401 without having the driver hang off the back. So the bass cab is about the same dimensions as a LaScala bass bin? And the height of the motorboard would be about the same as the full LaScala cab height? Trying to get this into my imagination to approximate real world dimensions. Quote Link to comment Share on other sites More sharing options...
BEC Posted November 18, 2004 Author Share Posted November 18, 2004 Dee, The front is almost exactly the size of a Lascala (or a Cornwall). Depth is also about the same as a Lascala. The mid-driver extends back to almost the back of the bass cabinet just as in the Lascala. Bob Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted November 18, 2004 Share Posted November 18, 2004 Thanks Bob. I'm thinking. Could be dangerous. Probably harmless. Quote Link to comment Share on other sites More sharing options...
jwc Posted January 22, 2005 Share Posted January 22, 2005 Bob, This thread seems to have died and I keep checking for it to pop up again. I am very curious about your testing of this cabinet with different drivers. It's been a couple of months now. Have you got any update? thanks jc Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 22, 2005 Share Posted January 22, 2005 ---------------- On 1/22/2005 8:12:59 PM jwcullison wrote: Bob, This thread seems to have died and I keep checking for it to pop up again. I am very curious about your testing of this cabinet with different drivers. It's been a couple of months now. Have you got any update? thanks jc ---------------- JC, you were reading my mind tonight. Whats going on Bob? Terry Quote Link to comment Share on other sites More sharing options...
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