redtop Posted August 9, 2005 Share Posted August 9, 2005 How important is the location of the ports on a KLF-30? I've got one that I "HornEd" modified into a horizontal center channel. I would like to know the ramifications of moving the ports to the front of the speaker, so that I have the ability to set it back closer to the wall. If port size is more important than location, does it matter where and how they are positioned on the front? (i.e. separated - one at each end...instead of next to each other?) Thanks in advance. Quote Link to comment Share on other sites More sharing options...
jwc Posted August 9, 2005 Share Posted August 9, 2005 I will jump in with the same question. I spoke of this topic some time ago on this forum.. I can't remember where it was. I was considering building a clone of the KLF 30 with a different mid horn and tweeter. I also wanted to move the port to the front. I didn't get a lot of response. jc Quote Link to comment Share on other sites More sharing options...
marems Posted August 9, 2005 Share Posted August 9, 2005 Hello, I was thinking of doing the same to my 20's I was even thinking of putting the mid and tweet in the center just like the epics that have the D'Appolito alignment. But overall I don't think that putting the ports in the front would mess with the sound of the 30's, I also believe you won't have to be so room placement critical as you have to be with rear ports. I do like a front ported speaker better than a rear ported one for the fact that you don't lose bass in the back wall. I have also looked into ports that have wide flares on both ends, you can gain up to 3db with the flares on both ends. But I measred the O.D. of the port in the KLF's and the actual hole in the KLF's for the ports are 4.30". while the actual exit is 3.30" so if one was to go to a flared port you would have to use a 3" port but then you are down sizing the port by .30" and that might be a problem. So mabe stick with the orginal ports. Good luck, and let us know how they sound. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted August 9, 2005 Share Posted August 9, 2005 it might change the phase of the port output compared to the woofer output. Check with DrWho, he's up on all this cabinet engineering stuff. Michael Quote Link to comment Share on other sites More sharing options...
Jay L Posted August 10, 2005 Share Posted August 10, 2005 where the port exits in the rear of the cab makes no difference, and shouldn't matter if you put it on the front either. but when you go moving those 2 woofers further apart, the polar response suffers a bit. i measured mine, but i don't think i can post it. Quote Link to comment Share on other sites More sharing options...
jwc Posted August 10, 2005 Share Posted August 10, 2005 ---------------- On 8/10/2005 6:33:24 AM Jay L wrote: where the port exits in the rear of the cab makes no difference, and shouldn't matter if you put it on the front either. but when you go moving those 2 woofers further apart, the polar response suffers a bit. i measured mine, but i don't think i can post it. ---------------- Dude...post it. Quote Link to comment Share on other sites More sharing options...
STL Posted August 10, 2005 Share Posted August 10, 2005 You can move the ports to the front and/or go from 1 port to 2 smaller ports. I can help you determine the size and length of the two smaller port if you'd like. Leaving the enclosure sealed might work too (at the expense of low freq. output), but to truly know I would need the T/S parameters of the driver. If you want me to figure out the port stuff, let me know the following: 1) stock port diameter 2) stock port length 3) interior volume of the stock enclosure (or the interior measurements) Also note, the more accurate your measurements the more accurate my calculations will be. Quote Link to comment Share on other sites More sharing options...
redtop Posted August 10, 2005 Author Share Posted August 10, 2005 Thanks for the replies guys. I sure will be glad when Amy gets the e-mail notify turned back on. I've been a little late getting back to this thread because I was waiting for the notifications...doh! STL, How much falloff would you expect in the low frequencies in a sealed enclosure? If it's not too bad and since this is a center channel, maybe I shouldn't worry at all and just position it so that the ports have a couple of inches to "breathe" a little. I know I've seen several posts on the forum recommending to have at least 12-18 inches behind the ports, but I've always wondered if this advise was more about the room dynamics than actual speaker port performance. Any thoughts on this appreciated. Quote Link to comment Share on other sites More sharing options...
STL Posted August 10, 2005 Share Posted August 10, 2005 Sealing the enclosure and leaving the port on the back without enough room to breath are two differnt things. Without the T/S parameters, I cannot really know how the woofers will react. Some woofers can work in both sealed and vented enclosures, while other are made more specifically for sealed or vented applications. If the woofer is really optimized for a vented application, then you'll really lose a lot sealing it. Leaving the port on back and not giving it room to breath could very well lead to a lot of unwanted port noise. BTW I don't thin you really need 12-18 behind the port. A better rule of thumb is twice the internal diameter of the port (in all directions) but you might be able to get by with a little less. Quote Link to comment Share on other sites More sharing options...
redtop Posted August 10, 2005 Author Share Posted August 10, 2005 STL, Thanks for offering to "calc" my ports... There are two circular ports (side by side)that taper as they extend into the speaker cabinet. On the cabinet surface they are 3 3/4" in diameter and taper down to 2 1/2". The port extends 2 1/2" into the cabinet. Look forward to your thoughts on distance from the back wall as well as possible positioning on the front. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
jwc Posted August 10, 2005 Share Posted August 10, 2005 ---------------- On 8/10/2005 8:08:22 PM redtop wrote: STL, Thanks for offering to "calc" my ports... There are two circular ports (side by side)that taper as they extend into the speaker cabinet. On the cabinet surface they are 3 3/4" in diameter and taper down to 2 1/2". The port extends 2 1/2" into the cabinet. Look forward to your thoughts on distance from the back wall as well as possible positioning on the front. Thanks in advance. ---------------- Red Can you show a picture of that port? Are your speakers disassembled? jc Quote Link to comment Share on other sites More sharing options...
redtop Posted August 11, 2005 Author Share Posted August 11, 2005 jc, The speaker is still assembled and I can take a picture of the ports later tonight, if that will help. BTW, where are you located in GA? I'm NE of ATL about 45 minutes. Quote Link to comment Share on other sites More sharing options...
jwc Posted August 11, 2005 Share Posted August 11, 2005 Pictures would be good. Infact, I would love to see your center channel. I live about 40 minutes west of Atlanta. My mother lives in Cumming and my sister in Monroe. jc Quote Link to comment Share on other sites More sharing options...
DrWho Posted August 11, 2005 Share Posted August 11, 2005 I take it this is what the center channels look like: W T W (woofer tweeter woofer) What's wrong with doing this kind of an arrangement: P W T W P (port woofer tweeter woofer port) I wouldn't recommend going to a sealed enclosure...these drivers were definetly designed to be ported. (going sealed would introduce a widehump in the response in the 60-120Hz range, which would totally destroy the balance of the speaker, requiring EQ and/or crossover changes). In fact, tuning the cabinet waaaaay too low would come closer to a "sealed cabinet response". But since the whole purpose behind this center channel was to timbre match everything, I don't see the benefit. Of the people doing these center channel builds, are any of you guys looking into 2.5 way crossovers (aka taperred array)? It would certainly remedy the polar response issue. Quote Link to comment Share on other sites More sharing options...
STL Posted August 11, 2005 Share Posted August 11, 2005 redtop, I didn't realized the KLF-30 had two ports. Sounds like you're all set to just move them to the front like DrWho illustrated. Quote Link to comment Share on other sites More sharing options...
redtop Posted August 12, 2005 Author Share Posted August 12, 2005 jc, I guess that would put you in the Villa Rica/Douglasville area? Sounds like you get to travel 285 a bit to visit the rest of the family! See next post for pic of my center... Quote Link to comment Share on other sites More sharing options...
redtop Posted August 12, 2005 Author Share Posted August 12, 2005 Here is the pic of the center. Please excuse the photo's orientation as it is currently in storage as I am in the middle of finishing my theater room. Dr. Who, Thanks for the input. I'm certainly not against re-working the motorboard (I did it once already...)to re-configure for front ports. I just wasn't sure what was to be gained or lost. I trust Klipsch to design and place speaker components where they make the most sense, so I am always a little leery of just trying stuff that pops into my head. You and STL obviously understand the engineering principles better than I. If there is any other input, I welcome it. Thanks to all replies. Quote Link to comment Share on other sites More sharing options...
STL Posted August 12, 2005 Share Posted August 12, 2005 As mentioned before, when you redo the motorboard be sure to move the woofers "in" towards the center as far as you can. With doing that will create couple areas (between the woofers and horns) where there isn't much wood so you might want to add a brace behind it. Make the brace so it snugly contacts the motorbard (at the "thin" spot) as well as what would be the top and bottom of the center enclosure. You can screw the brace to the motorboard and then just glue it (using clamps) to the top and bottom. Quote Link to comment Share on other sites More sharing options...
Lurch Posted August 13, 2005 Share Posted August 13, 2005 Does anyone know what the frequency response of the port looks like? Ports can get pretty ragged above the crossover point. If it is ragged, you might be better served with leaving it in the rear of the speaker! Quote Link to comment Share on other sites More sharing options...
Jay L Posted August 16, 2005 Share Posted August 16, 2005 ---------------- On 8/12/2005 9:58:49 AM STL wrote: As mentioned before, when you redo the motorboard be sure to move the woofers towards the center as far as you can. Make the brace so it snugly contacts the motorbard. ---------------- this is exactly what i did. Quote Link to comment Share on other sites More sharing options...
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