Ljk Posted March 17, 2017 Share Posted March 17, 2017 Not having much luck running the numbers for an 18 inch sa madrid sub. Only found one box design I could use with my tablet and the box size seems off. If it's not to much trouble could someone run the numbers, may be winbox for me? Seems sealed would be best for this sub but I am open to suggestion. Thanks Fs 48hz Rc 9.5 Qms 2.3 Cms 63mm Qes 1.1 BL 21.2 Qts .75 Mms 173.5g Vas 157.7 ltr Sd 1.3k cm 2 102 dB sensitivity Box is to be built out of 3/4 inch oak plywood. Freg. Range 25hz to 2k Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted March 17, 2017 Share Posted March 17, 2017 If you can link to the manufacturer's page with the complete T/S parameters I would be happy to model in WinISD. I don't think that is enough data for modelling as is. Quote Link to comment Share on other sites More sharing options...
Ljk Posted March 17, 2017 Author Share Posted March 17, 2017 7 hours ago, RoboKlipsch said: If you can link to the manufacturer's page with the complete T/S parameters I would be happy to model in WinISD. I don't think that is enough data for modelling as is. http://www.seismicaudiospeakers.com/18-inch-raw-subwoofer-driver-speaker/p/New-Madrid-18 If you scroll down to specs and click more you will see the T/S parameters. If you need more info let me know and I will call tech support. Thanks! Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted March 18, 2017 Share Posted March 18, 2017 Below is my model of the driver in a sealed box. There may be a few here who build these for a living that can do better so I just wanted to put that out there. My goal designing it was trying to get you to .707 alignment, which I understand to be more or less an "ideal" alignment for sound quality. The driver wants a lot of box space and so what I did here as you will see is stuff the boxes pretty heavily in order to lower the QTC. The highlighted one is a 12 cubic foot sealed box, stuffed heavily, resulting in a QTC of .707 (roughly). XMAX limited at 13mm (it probably does more but that is the mfg spec), you can see the output. Option 2 I am showing is a smaller box coming to 6.9 cubic feet, stuffed to the max it results in a QTC of .741 (roughly). XMAX limited at 13mm you can see the SPL output. These designs are the maximum stuffing, so the QTC can only be lowered by having an even bigger box. So put another way, you can continue to make the box smaller but are having a different QTC alignment. I do not know your goals or QTC goal. If it is higher, the box can be made smaller. I know some people do a 1.0 alignment, but from my limited knowledge, shooting for roughly .707 is a good spot. I can modify the models to suit your ideas/plans, just let me know. I do not know how to design ports properly so I can only plug something in regarding a vented sub and see what it does. RK Quote Link to comment Share on other sites More sharing options...
Ljk Posted March 19, 2017 Author Share Posted March 19, 2017 On Friday, March 17, 2017 at 0:12 PM, RoboKlipsch said: If you can link to the manufacturer's page with the complete T/S parameters I would be happy to model in WinISD. I don't think that is enough data for modelling as Would it be possible to chart 8cu ft sealed with above gtc and at 1.. Hope my editing has not caused any problems, thanks. Quote Link to comment Share on other sites More sharing options...
racebum Posted March 19, 2017 Share Posted March 19, 2017 that qts is way way too high to go ported. box will be absolutely gigantic. honestly i would use another sub or sealed and dsp with a LOT of amp power if you try porting something with that high of a Q in a smaller box it's going to be peaky and fall off, it will most likely sound like a giant midbass in that kind of design build to a .707qtc sealed and you have already been given that model. get a LOT of amp power and dsp it. ported would literally be a refrigerator size box the fall off curve on that looks more like a pro audio driver than HT. have you considered using multiples of a good 12 like the css sdx 12 or 15s if any good ones still exist? box space is usually the limiting factor with subs and this 18 just wants too much Quote Link to comment Share on other sites More sharing options...
Ljk Posted March 19, 2017 Author Share Posted March 19, 2017 Thanks racebum, for mobililty I really don,t want go over 8 cu ft. so I guess its 8cu ft sealed and stuffed to the max. Looking at the chart again I guess 8 cu ft is not going to change the plot much. Maybe gtc of 1. might? I am guessing not. For now I have to live with this sub down the road may be I can try something different. I was looking at the dayton ultimax 15 before my work truck broke down , in the future may be. . Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted March 19, 2017 Share Posted March 19, 2017 The models are sealed. Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted March 19, 2017 Share Posted March 19, 2017 New Madrid SA 18 8cft.bmp Here is 8cft - note this is NET, not the gross you have to account for braces and driver in the computation. The taller graph has no PEQ, the flatter graph has 8db of EQ at 35db, Q=2. 1100 watts for the 8cft without PEQ to reach XMAX 200 watts for the 8cft with 8db of PEQ at 35hz to reach XMAX, apparent power is roughly 1000watts (what you'd need to have in the amp for this) That is just one option for PEQ, how much and where you do it is up to you. There is no doubt this is a pro driver designed for that middle range bass to blast from 40 and up. With the PEQ it looks to me like the -6db point is around 30hz, and the -12db (point where it will probably be hard to hear in comparison to the higher frequencies) is 25hz. That's not bad. It's just designed for pro use which means high SPL and not so much concern or interest in the very low tones which can make a live venue difficult to EQ for those purposes. At home it should work fine. You just have to know what you are getting into. I have 2 8cft net (probably more like 10 or 11cft gross) that have Ultimax 18s in them. They easily go flat to about 15hz and play down to 10hz at -6db or so. That's the difference between a pro design and the designs built more for home theater. Nothing wrong with what you are considering building, it will do the job great, you won't hear much under 25hz though is my thought. It costs about $100 more for a Ultimax 18 (FYI). RK Quote Link to comment Share on other sites More sharing options...
RoboKlipsch Posted March 19, 2017 Share Posted March 19, 2017 Sorry it is a bitmap and must be clicked, it's Sunday and my brain is no longer functioning properly and I can't make a picture save right anymore Quote Link to comment Share on other sites More sharing options...
Ljk Posted March 20, 2017 Author Share Posted March 20, 2017 9 hours ago, RoboKlipsch said: Sorry it is a bitmap and must be clicked, it's Sunday and my brain is no longer functioning properly and I can't make a picture save right anymore No problem thanks for the help!. I am going to try an 8 cu ft box for now and see how it does. Down the road once when my truck is fixed and have more funds maybe I wiil try an ultimax. Thanks again! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.