DrWho Posted October 10, 2005 Share Posted October 10, 2005 You're looking at almost exactly half the volume with the dimensions you listed. There is no way in the world you could get the two woofers to work with that volume unless you purchased two more and did an isobarik arrangement. Your other option would be to use a single woofer and a single port. This will maintain the same tuning and same slope, but you will lose 6dB in the bass....this would then require you to drop the HF section by 6dB to maintain the balance through the speaker. Sadly this is going to increase woofer excursion by 4x for the same SPLs, which will have an audible impact. The isobarik configuration loses 9dB, but compensating back to the same volume results in the same excursion while also reducing 3rd order harmonic distortion. So the only disadvantage here is making sure your reciever has enough power to compensate for the 9dB difference (which equates to 6x the power requirements). Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 10, 2005 Author Share Posted October 10, 2005 Well, I'll let ya know cuz for now that is the size. Maybe later can I build one the correct size but for now this is it. I'll let ya know if it works. I suspect it's gonna be fine for now. I set my center to small anyway. Should I go ahead and put the 2 ports in? Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 10, 2005 Share Posted October 10, 2005 I attached a picture that shows what effect such a process will have on the frequency response. I didn't model the exact same driver so the actual frequencies will be slightly different. The red line is the normal response to which the other two colors whould be compared. Both the green and blue lines are half the cabinet size of the red line, all three are modelling two drivers. The blue line indicates the response when using one port and the green line indicates the response when using two. The KLF-20 indicates a -3dB point of 34Hz so I think it's fair to assume a 40Hz tuning (I could be more precise if you knew the dimensions of the port). So using 2 drivers in a cabinet half the ideal size will result in 6dB less output at 40Hz or wherever the tuning point is (very similar to the graph I plotted....hmmm imagine that) [] I hope this helps...it wasn't nearly as bad as I thought it might be. Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 11, 2005 Author Share Posted October 11, 2005 So, if I have the center set to small and nothing below 80hz is going to it, I should be ok, at least until I can work in the correct size box? Quote Link to comment Share on other sites More sharing options...
Jay L Posted October 11, 2005 Share Posted October 11, 2005 imo i would get two klf-c7 woofers and rework the xover to use the midrange and tweet from the klf-20. unless you already have the 20 woofers... don't over stuff the enclosure with polyfill if your going sealed, if ported just throw some foam on the walls, no need to stuff it. Quote Link to comment Share on other sites More sharing options...
billyjoe72 Posted October 11, 2005 Share Posted October 11, 2005 FYI...I built my own out of a scrapped klf10 and it sounds great. It's not shielded and has to be about 20 or so inches from my TV. Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 11, 2005 Author Share Posted October 11, 2005 FYI...I built my own out of a scrapped klf10 and it sounds great. It's not shielded and has to be about 20 or so inches from my TV. Ya, you got the ones off EBAY for 90 or so bucks, right. I wanted them but blew it. So I had the luck to buy the parts from Klipsch for $440, but I'm happy. In fact, I'm waitin' for paint to dry right now on the new box. Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 11, 2005 Author Share Posted October 11, 2005 It is done! Hooked up and running. It is late so I wasn't able to really push it, but I did try out a few multi-channel audio selections. Fleetwood Mac Rumors was one test. Stevie Nicks always sounded kinda wierd singing Dreams on the C7, and some of that has to do with the recording, which is good but just not the FWM Rumors I grew up with. Anyway, it sounded really good with the new center. Tomorrow I will really give it a go and recalibrate things, etc. It sounds great in that smaller box. I may just stay with that. Thanks for all the input during this project. Billy Quote Link to comment Share on other sites More sharing options...
sunburnwilly Posted October 11, 2005 Share Posted October 11, 2005 " Way ta get er' done Billy !!! " [H] Quote Link to comment Share on other sites More sharing options...
redtop Posted October 12, 2005 Share Posted October 12, 2005 Wow that was fast! Got any pics? I showed you mine...now you show me yours...[][] Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 12, 2005 Author Share Posted October 12, 2005 Wow that was fast! Got any pics? I showed you mine...now you show me yours...[][] Hope this pic shows up. The enclosure is one of my original Scott 188t speakers. I had to cut out the original motorboard because this thing is built like a tank; double thickness MDF and glued to high heaven....I left about 1 1/2 " all the way around and cut a piece of 3/4" plywood to fit, then cut out the holes. I cut out 2 ports in the back the same size and installed the flared ports for a klf 20. Once I make a new speaker grill it will be slick. I may re-veneer it but let me tell ya, we ain't exactly interior decorators around here so it'll prolly ride just like that. Like I said, this enclosure is rock freakin solid and the speaker sounds unbelievable. Next question: Do I keep the rear surrounds as (2) RB 35s or a single C7? I mean, until I get ANOTHER C7. Quote Link to comment Share on other sites More sharing options...
redtop Posted October 12, 2005 Share Posted October 12, 2005 The pic didn't show. Make sure you use the file attachment field at the bottom of the messge reply screen. I know there is a button that says "Insert Image", but that does not work except on your computer. For the rest of us to see a pic it has to be added as a file attachment. Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 12, 2005 Author Share Posted October 12, 2005 try this Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 12, 2005 Share Posted October 12, 2005 ooo perty [] Quote Link to comment Share on other sites More sharing options...
formica Posted October 13, 2005 Share Posted October 13, 2005 The enclosure is one of my original Scott 188t speakers. I could see why you didn't want to mod the dimensions... BTW, if you ever feel like building larger enclosure, you can use a deeper cabinet with a similar motorboard... Quote Link to comment Share on other sites More sharing options...
redtop Posted October 13, 2005 Share Posted October 13, 2005 Nice job Billy! Looks like you had to be really precise to get everything to fit...[] Just remember, we talk a lot about theoretical optimums here on the forum. Whether your cabinet size is "perfect" or not doesn't matter...unless it matters to you. It the speaker you have built sounds good to you, that is all this forum is about...offering our experience and suggestions to those who are traveling uncharted waters. I thank you for starting this thread. It has brought new ideas and approaches to my attention and I shall be experimenting with some of them in the near future. Happy Klipsch-ing! Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 13, 2005 Author Share Posted October 13, 2005 Thanks,it fits in there just like I need. I'm not into moving the computer right now and frankly don't have time to do all that, build a box(or even get one built), etc. One day I may make it the optimum size but looking at Who's graph I'm not losing out on anything if nothing under 80hz is going to the speaker. It is definitely doing what I need in the midrange and up area. This is a major upgrade from the C7. Thanks again to all for participating. I declare this thread officially dead!! But I will start another one on the rear surround question right now. Billy Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 13, 2005 Share Posted October 13, 2005 Just curious...did you get a small hump in the 100Hz region? Perhaps making the center "muddier" sounding than the mains (muddy as in a relative term - it can be muddier without sounding muddy). The reason I ask is that different drivers behave differently when the ported cabinet size is too small. You'll notice it slightly on the graphs that there is an ever so slight boost in that range. Quote Link to comment Share on other sites More sharing options...
wstrickland1 Posted October 14, 2005 Author Share Posted October 14, 2005 Just curious...did you get a small hump in the 100Hz region? Perhaps making the center "muddier" sounding than the mains (muddy as in a relative term - it can be muddier without sounding muddy). The reason I ask is that different drivers behave differently when the ported cabinet size is too small. You'll notice it slightly on the graphs that there is an ever so slight boost in that range. I can't hear it. It sounds so much clearer and more balanced than the C7 that it's hard to imagine it getting any better. That's not to say it can't, but I simply cannot hear a hump in the 100 hz region. One day when my lazy butt has some time and money, I will get a box built that is the right size and then I will MAYBE be able to tell a difference, but I doubt it.. I do recognize that there are those who can detect this sort of thing, I'm simply not one of them. Billy Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 14, 2005 Share Posted October 14, 2005 Well I'm not saying the hump is there either - glad it's working out for you. Quote Link to comment Share on other sites More sharing options...
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