Change my mind-Ported subs cant touch sealed - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 116Likes
Reply
 
Thread Tools
post #1 of 201 Old 07-16-2019, 07:27 PM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Question Change my mind-Ported subs cant touch sealed

Greetings-


Not trying to make a fight club here...Ive been modeling subs for the last week, and every one with all things being equal sealed spank ported. Again this is with all things equal, same number drivers same cab same power. Sealed always extends deep into a black hole where as ported don't but you get a bit more spl(sometimes).



Example here is Two RSS390HF modeled in 6FT3 cabs both with 800 watts- Sealed barely crests excursion but im sure it'll be fine. I run mine now 500w 4.3 no filter all day and they laugh.


Ported has tiny bit more SPL - But sealed is like see ya! and keeps on digging. I used REW to measure mine- and YES I KNOW they need tweaking(MTG advised me im just working a lot this week) but mine dig into the single digits in my opinion like a boss. Mine are single woofer loaded 4.3ft3 sealed cabs.


Even doubling the ported cab to 12ft it still got left behind in extension. Also I chose 6ft3 because its a decent size(middle ground for me) and with excursion it was actually way easier to tame with the ported.



Yes I can go horn/TL style, heck i bought THTLP plans!!!! I was about to build two 7' tall monsters! until i heard they weren't meant for under 20hz..And as a Theater Junkie who goes all kid in a candy store when LF is shaking my room...I cant live with out it. Also the plywood total price it would have costed me was insane- I could have bought two more woofers for the cost of all materials. And honestly I was sad, I really wanted them to be my subs for the next few years. I had plans to make them into family collage- Of all of my kids from birth to present day- Figured that be a awesome thing to have in our theater/family room.



I gave ported a chance..Hell i cut a large ass hole in the tops of my cabs and stuck big ol PVC in there(modeled of course lol) and made a port tuned to like 18HZ based on WinISD and 12volt and it sucked. I felt like I lost all bass


Again I know my sweep is sloppy as i have not tamed it or tried to make it flat-but you cant deny that extension is good for a $180 driver.



Anyway- Im a broke [email protected]@ [email protected]@@, i support my wife and three kids with a crappy income, so I cant afford big ticket woofers. Even the UM18 are out of my reach, I can possibly buy two more of these when i save a little but unless the UM15 drops on sale again to $190- HF woofers are my golden ticket.





In closing---This is not a troll post, Its full of grammar mistakes and full of my experiences and what im seeing using WinISD/BB-Pro and Basta. and I just want to see some ideas and hear what this awesome community has to say and offer.



--What he forgot to say why!!! Well because I want a weee bit more, as we all do. And ive seen a lot of designs revolving around slapping twp woofers and gobs of power hehehe
Attached Thumbnails
Click image for larger version

Name:	1.PNG
Views:	126
Size:	51.7 KB
ID:	2591622   Click image for larger version

Name:	2.PNG
Views:	119
Size:	76.7 KB
ID:	2591624   Click image for larger version

Name:	62450500_636236513538630_7936234470695239680_n.jpg
Views:	115
Size:	48.9 KB
ID:	2591628  
Remy.Alexander is offline  
Sponsored Links
Advertisement
 
post #2 of 201 Old 07-16-2019, 07:44 PM
AVS Forum Special Member
 
trilkb's Avatar
 
Join Date: Mar 2017
Location: Cincinnati, Oh
Posts: 1,204
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 655 Post(s)
Liked: 333
Yes that's how ported boxes work, more spl at or around port tune. Sealed you can push to lower freq. Go explore "large low tuned ported boxes". Sealed are great, easy to eq as well. But if you want 17hz to be loud you build a ported box to 17hz. There's also horn boxes. But in general a sealed enclosure can do everything best (given the highs and lows between pros and cons). Freq range, spl through the freq, etc. It's all what you want that tells you what box you need. I run 8 sealed 12s and love them, but I need 8 sealed 12s to do what a 15" did in a 16' folded horn in terms of spl.

When modeling maybe you are doing something wrong. I just looked at the graphs and that's not right at all.
lknhomeaudio, kagtha and Will P like this.

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -

Last edited by trilkb; 07-17-2019 at 07:52 AM.
trilkb is offline  
post #3 of 201 Old 07-16-2019, 08:00 PM
AVS Forum Special Member
 
smcmillan2's Avatar
 
Join Date: Jan 2012
Location: Farmington, MI, USA
Posts: 2,024
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 875 Post(s)
Liked: 782
I guess I don't understand the question.

It's well known that (generally, still depends on driver, box size, etc.) sealed roll off slower than ported, so in the same outer dimensions sealed should dig lower than ported from a given point. Are you asking why?

Sub builds: Yet another Infinity 1260 build | Twins! | Modified V.B.S.S. build | UM12-22 builds | AV stand and sealed UM18s

Speaker builds: DIYSG HTM-10 build | DIYSG Volt-6 build | DIYSG Fusion-8 builds
smcmillan2 is offline  
Sponsored Links
Advertisement
 
post #4 of 201 Old 07-16-2019, 08:23 PM
Senior Member
 
CrusherW9's Avatar
 
Join Date: Apr 2016
Location: Central Iowa
Posts: 355
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 213 Post(s)
Liked: 127
I think the main issue is that you're limiting yourself to comparing alignments using a 390HF. Regardless, I recreated the models myself using the same driver, both in 6cf enclosures, and the ported one tuned to 20hz. The sealed alignment is running out of excursion even at 200w. I've attached a picture of my models on the "Maximum SPL" graph which shows the ported config firmly ahead when factoring in xmax as the limit. I've also attached a picture of the xmax graph at 800w. Running a driver over 2x xmax is.... probably not good. But perhaps my models aren't valid because I'm currently running WinISD in wine and using an old driver file I got out of a zip file from somewhere. Lastly, does it really matter what your extension is if you're 30db down at 10hz? Unless you have a lot of sealed subs to provide sufficient SPL down that low and shape the response to be flat, I don't see the point.

EDIT: Your "ported" model in WinISD is titled "Dual Ported". Is that a dual driver config? Additionally, your high pass on the ported model could be a higher order and it wouldn't reduce the 20-30hz range as much.
Attached Thumbnails
Click image for larger version

Name:	Screen Shot 2019-07-16 at 10.17.15 PM.png
Views:	102
Size:	43.5 KB
ID:	2591650   Click image for larger version

Name:	Screen Shot 2019-07-16 at 10.21.54 PM.png
Views:	80
Size:	60.3 KB
ID:	2591658  

"Becoming educated is more than just acquiring knowledge. It involves the ability to see the world in ways never before conceived."

Last edited by CrusherW9; 07-16-2019 at 08:30 PM.
CrusherW9 is offline  
post #5 of 201 Old 07-16-2019, 09:52 PM
AVS Forum Special Member
 
zora's Avatar
 
Join Date: Nov 2003
Location: Walla Walla, WA
Posts: 1,058
Mentioned: 2 Post(s)
Tagged: 1 Thread(s)
Quoted: 103 Post(s)
Liked: 82
Get multiples of the $29 JBL driver on sale now. Extension & cheap.
tjcinnamon and bebb like this.
zora is online now  
post #6 of 201 Old 07-17-2019, 02:43 AM
AVS Forum Special Member
 
bear123's Avatar
 
Join Date: Dec 2013
Location: PA
Posts: 6,343
Mentioned: 77 Post(s)
Tagged: 0 Thread(s)
Quoted: 2600 Post(s)
Liked: 4080
Playing devils advocate...I could argue that ported subs are drastically superior to sealed. With one or two inexpensive drivers, the extra output and extension you would have below 12Hz or so will be totally meaningless....not enough SPL to hear or feel anything from, and this only on a very minuscule amount of content compared to the 15Hz+ content where the ported subs will have drastically higher ouptut(2-3x more output around port tune) with much lower distortion and much higher tactile response.

In this scenario, the ported subs win in a big way. The only disadvantage is a larger cab that is not quite as easy to build.
bear123 is offline  
post #7 of 201 Old 07-17-2019, 02:50 AM
Senior Member
 
Join Date: Jul 2017
Location: Manchester, UK
Posts: 269
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 103 Post(s)
Liked: 164
If you're getting similar spl with ported and sealed something in you're modelling has gone wrong. Ported boxes offer wayyyy more spl than their sealed counterparts. For example a 21ds115 in a sealed cab vs a ported 12 cuft, only offers more spl below about 13hz, if you're bothered about single digits then go sealed, but like many others who only really care about +15hz I cant think of any reason to go sealed over ported.

Sent from my SM-G950F using Tapatalk
scottvalentin likes this.
monty6400 is offline  
post #8 of 201 Old 07-17-2019, 05:13 AM
AVS Forum Special Member
 
EndersShadow's Avatar
 
Join Date: Apr 2009
Location: Indianapolis
Posts: 6,138
Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 1234 Post(s)
Liked: 1516
There is no "best". They are two variations, both of which have pro's and cons. Which you pick will depend on a variety of factors specific to you, such as room size/construction/dimensions, the biggest box your willing to deal with, power on tap, driver size, your access to tools/flatpacks ect.

Also, WinISD gives you numbers, but as mentioned those numbers aren't the full picture. Take a sub and put it on concrete, and put it on a wooden sub-floor, you get two VERY different responses, but WinISD wouldn't show you that.

Then lets not forget the "Equal Loudness Contour" which shows that the lower in frequency range you go, the more SPL you need for the illusion of the same SPL of higher frequencies.....

In practice this means you need MORE SPL down low than up top so the WinISD chart showing that the sealed dig deeper wont actually translate normally into actual sound you can feel unless you are at crazy SPL levels.



The graph above is cleaner, but the graph below helps explain what your looking at.



In my situation if my wife would have allowed it, I'd go for 2 big large ported boxes, using big large drivers tuned low. I'd be taking up lots of space in the room, but I wouldnt need tons of drivers, I would get good ULF, and wouldnt need tons of amps/power/EQ to get a decent response. But she wont. So instead I'm going sealed with 12 of the JBL CS1214 spread across 4 enclosures, with a MiniDSP to EQ and 4 amps with around 2k each of power. With work I should be able to get what I want, but with all things you compromise. In my case my compromise was driver size, which helped dicatate box size, power & eq requirements.

But in general one is better than the other. And your also forgetting there are other options, also with pro's and con's, such as horns, infinite baffle, etc.

There is no "best" for everyone, there will be a "best" for you, but again its unique to your specific configuration and can't be generalized to apply to everyone.

My Setup | Custom MiniDSP Build | FS: If its For Sale, find it all (here)
Quote: There exists, for everyone, a sentence - a series of words - that has the power to destroy you. Another sentence exists, another series of words, that could heal you. If you're lucky you will get the 2nd, but you can be certain of getting the 1st. - Philip K. Dick

Last edited by EndersShadow; 07-17-2019 at 05:25 AM.
EndersShadow is online now  
post #9 of 201 Old 07-17-2019, 07:16 AM
Advanced Member
 
Jedi940's Avatar
 
Join Date: Dec 2009
Location: Northwest Ohio
Posts: 509
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked: 202
If your sealed output matches your ported output in modeling, it's because your ported box is undersized. To realize the benefits of a ported box, you usually need to double the sealed volume. A port in a box that's too small doesn't have any benefits over sealed.

Below is a graph with the 390 in a 6 cu.ft. sealed vs a 12 cu.ft. ported. Port tune is around 17Hz. Signal is 250 watts keeping excursion in check.



The difference at 20Hz is 109db vs. 102db in the sealed. This is the benefit of a ported box. More around the tuning frequency. The "cost" is the bigger box size.

In a smaller box size, 3 sealed vs. 6 ported, you can see the benefits of ported are less pronounced. This model is with 400 watts each still tuned to 17Hz. Since the box is smaller, it can handle more power without the risk of over-excursion.



The difference at 20Hz here is 102 sealed vs. 107 ported. You can also see the roll off is more gentle. It also shows that there is very little benefit from a 6 vs a 3 cuft box sealed other than being able to achieve the same volume with less power. On the other hand, in a ported, 6cuft box at 400 watts, 17Hz output is 103db while ported in a 12cuft box with only 250 W at 17Hz gives you 107db. That's a 4db gain at the tuning of the box.

Everything is a trade off. If you have the space and resources to build bigger boxes, you can realize some significant gains moving to a larger ported box for your subs. The bigger the box, the better the gains. Is a 12cuft box optimal for this 15" sub, probably not as there are better options but working with what you have, it should give you a better experience.
Attached Thumbnails
Click image for larger version

Name:	rss390.png
Views:	308
Size:	8.6 KB
ID:	2591768   Click image for larger version

Name:	rss390_smaller.png
Views:	342
Size:	9.4 KB
ID:	2591770  
LTD02, Heide264 and bebb like this.
Jedi940 is offline  
post #10 of 201 Old 07-17-2019, 07:58 AM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Yes both designs area dual woofers. Both 800W 6FT3 cabs Im only "down" at because I haven't gotten around to "tuning" my setup. When I get the time today or tomorrow to do as mtg suggested, it would look basically flat to 10hz. I was modeling dual woofers for the space saving and ability to push them harder vs single loaded cabs. space is limited-I can pull off two cabs and thats about it, but was looking to get every last drop out of them, and it seemed that dual loaded was better.

I have looked into TL/Horn, I suck at Hornsrep and as mentioned in OP i purchased the plans for the THTLP-I just got a lot of feedback they weren't meant for under 20hz. As for the single digits- yes there is not as much out there as 15+ but its there. You dont need gobs of spl to get the feel of it. Granted im at 100+DB but i dont need to go further there.

I was hoping going ported would get me a bit more- for some reason my "max spl" shows nothing haha- Im just chasing the best design for these subs. I dont see much love here for them which is sad because price vs performance is insane. Yes UM15 has more Xmax- but i compared them in winsid and they are about equal for spl so not worth the extra $50 per woofer
Remy.Alexander is offline  
post #11 of 201 Old 07-17-2019, 08:55 AM
AVS Forum Special Member
 
trilkb's Avatar
 
Join Date: Mar 2017
Location: Cincinnati, Oh
Posts: 1,204
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 655 Post(s)
Liked: 333
Quote:
Both 800W 6FT3
thats your problem. You are actually reducing the cabinet size even more by adding the port when you should be at 12cuft.

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -
trilkb is offline  
post #12 of 201 Old 07-17-2019, 09:00 AM
Member
 
drewp29's Avatar
 
Join Date: Mar 2010
Location: Southern Colorado
Posts: 151
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 63 Post(s)
Liked: 60
Jedi's response is probably the best here, based on the benefits of porting being at the expense of box size, and I agree, your graphs look off. The graphs Jedi posted are more in line with what I have seen in my experience.


If you have enough power on tap, enough cone excursion capability, and enough thermal power handling, you can tune a sealed response to yield quite good results down into single digits. However, those requirements usually mean high dollar subs, and high-ish dollar amplifiers. I know there is someone here who knows the numbers off the top of their head for cone excursion required for increased dB's, but realize 3dB of boost requires twice the power. If you are already close to the thermal limit of the woofer, doubling power will likely melt things in short order.


Just looking at your measurement graph, there is no way you'll run flat to 10Hz. Even if you pull the 60-85Hz range down to 110dB, you still need to boost around 12dB, which will require A LOT more power than you have available, and the 390HF's will probably die in the process. They are beefy subs and can handle quite a bit more than their rated power, but you'll kill them trying to EQ flat to 10Hz. If that graph is utilizing, let's say 300W (based on your comment on excursion), to boost 12dB you would need to push 4800W into them. Not gonna happen.


My thoughts as to why you felt you lost output when you went ported is that you probably didn't subtract the port volume from your WinISD model. A gigantic port takes up a lot of room in the box, making the volume the woofer sees much smaller, and thus drastically changing your tuning frequency. For example, the box I am working on is 20 cubic feet gross internal volume, but after subtracting the port volume (8" diameter port, 48" long) my net volume is approximately 18 cubic feet. I lose 2 cubes from the port and bracing. I modeled in WinISD with an 18 cubic foot volume, which puts my port tune with the aforementioned port at around 11.5Hz. If I modeled a 20 cubic foot internal, my box would need to actually be 22 cubic foot gross to compensate for the loss of volume.


Edit to the last paragraph: And with 20 cubic foot net internal volume, my port length would need to change to stay at the 11.5Hz tune. This is even more drastic with smaller box sizes, e.g., losing 2 cubic feet of volume in a 6 cubic foot gross box is a huge difference compared to a 20 cubic foot box.

Last edited by drewp29; 07-17-2019 at 09:12 AM.
drewp29 is offline  
post #13 of 201 Old 07-17-2019, 09:10 AM
Senior Member
 
notfastenough's Avatar
 
Join Date: Oct 2017
Location: The Colony, TX
Posts: 380
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 188 Post(s)
Liked: 219
Quote:
Originally Posted by Remy.Alexander View Post
Yes both designs area dual woofers. Both 800W 6FT3 cabs Im only "down" at because I haven't gotten around to "tuning" my setup. When I get the time today or tomorrow to do as mtg suggested, it would look basically flat to 10hz. I was modeling dual woofers for the space saving and ability to push them harder vs single loaded cabs. space is limited-I can pull off two cabs and thats about it, but was looking to get every last drop out of them, and it seemed that dual loaded was better.

I have looked into TL/Horn, I suck at Hornsrep and as mentioned in OP i purchased the plans for the THTLP-I just got a lot of feedback they weren't meant for under 20hz. As for the single digits- yes there is not as much out there as 15+ but its there. You dont need gobs of spl to get the feel of it. Granted im at 100+DB but i dont need to go further there.

I was hoping going ported would get me a bit more- for some reason my "max spl" shows nothing haha- Im just chasing the best design for these subs. I dont see much love here for them which is sad because price vs performance is insane. Yes UM15 has more Xmax- but i compared them in winsid and they are about equal for spl so not worth the extra $50 per woofer
So, you bought the plans for THTLP, but simultaneously don't have room for larger ported boxes? I'm missing some logic here.

If you don't have square footage, but do have cubic feet, then a ported box with a low tune is obtainable.
notfastenough is online now  
post #14 of 201 Old 07-17-2019, 09:24 AM
Member
 
Join Date: Oct 2017
Posts: 120
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 45 Post(s)
Liked: 28
If you want something that performs well in a small vented box it helps to model subs that perform well in small vented boxes. The 390HF already requires a pretty large sealed enclosure for a 15, so proper vented one is going to be quite big comparatively. Note the HF runs out of excursion 35hz with 500w while the HO stays below 12mm throughout. The HO will still perform well in a enclosure smaller then this.
Attached Thumbnails
Click image for larger version

Name:	390HF VS HO 1.png
Views:	44
Size:	43.5 KB
ID:	2591840   Click image for larger version

Name:	390HF VS HO 2.png
Views:	39
Size:	35.0 KB
ID:	2591842   Click image for larger version

Name:	390HF VS HO 3.png
Views:	41
Size:	36.2 KB
ID:	2591844  
BigJake82 is offline  
post #15 of 201 Old 07-17-2019, 10:26 AM
AVS Forum Special Member
 
asarose247's Avatar
 
Join Date: Mar 2010
Location: DIY enabled in SoCal / OC
Posts: 4,405
Mentioned: 104 Post(s)
Tagged: 2 Thread(s)
Quoted: 1238 Post(s)
Liked: 1083
piling on . . .
this quote from the BFM site posted in 2006 . .

A little quote I just picked up on another forum which might help to put a bit of extra real world perspective on the views of doubling cabinets and stacking rules (some spelling and punctuation corrected)

Rog Mogale

"a wall like a floor will reinforce the output as you now have the speaker and another virtual speaker or mirror of the speakers output adding to it. This is providing the speaker is close enough to couple in wavelength terms to the adjacent floor or wall. So a horn that requires a mouth of 5000 sq cm to have a certain low cutoff can have this figure halved if its in contact with the floor or quartered if its on the floor and against one wall. Hence half space, quarter space and so on.

So at what point does a stack of speakers all combining in phase change from one operating condition to another? Well, if the stack is on the floor then its in half space, but I'm not convinced the more cabs you add the more it operates like it was in quarter space. It will happen to a certain extent but I think you still have a new larger speaker with a longer horn in half space. I never automatically change from half space to quarter space or eighth space if I model more than one speaker. For me its just a larger speaker with a longer horn and bigger mouth if its a horn. Its still in half space. Likewise I always model mid tops in free space even if there are 8 of them. Its still a speaker, all be it a large one thats in free space. Its a difficult question to answer and I have a couple of times before, but a stack of speakers operating conditions don't change as much as you think unless you go very big. The bigger the speaker and the larger its radiating surface is the less it starts to obey the inverse square law. Why? well you are more likely to be in the near field of a sound source if it is marginally larger than you are. Its like you are physically nearer and will also visually look like this as the stack grows.




Its a debate that still continues. I think you still have a larger speaker with increased coupling to the floor, a longer horn path and bigger mouth if using horns and the increase in efficiency that brings, but still working in the same space. You can also add any effects brought about via any decrease on the inverse square law if the stack is large enough. But one thing thats doesn't happen is that you automatically add 6dB everytime you double the amount of speakers. You will get 3dB from double the amp power as a result of the lower impedance and only if the amp delivers twice the output into the new lower load, but you can never get 3dB from a doubling of sensitivity. So be careful when knowing the output of one cab and then addding 6dB everytime you double the amout to work out the new combined output. It will never be as much as you expect due to cabinet losses which destructively combine to reduce the sensitivity and the fact that most amps don't double their output into half the impedance."

I personally found this insight very interesting and it confirms to me that theory and practice are very different."

FTR, now running 2 30" THTLPS off a nx3000D, 400 w., some PEQ @ 25hz, pointed at the ceiling-20" loading into that upper back juncture, in the 18" space behind my seating, the 10 x 10 ish cave.
I just spent 6 years babying them with the BASH amps. The TR is there when it needs to be. The response is there and all the previous detailed caveats are true. chasing that 10 hz , the exponential expense of drivers, and the power to attain 'audibility" - 1 tunnel in the rabbit hole . . .

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
asarose247 is offline  
post #16 of 201 Old 07-17-2019, 12:54 PM
Advanced Member
 
Russell Burrows's Avatar
 
Join Date: Oct 2007
Location: Tamaulipas Mexico
Posts: 601
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 79 Post(s)
Liked: 30
Had 4 12 inch subwoofers burblap blown ported forgot my amp setting then did a much larger ported 4 15 inch ported burblap blown ported forgot my amp setting and four very large useless subwoofer enclosures.

Said efff it and said no more blown subwoofers due to forgot my amp setting so i went infinite baffle and i like it a lot.
First the downsides needs a very large unused closet or spare room or attic space but in my case i said efff it and purpose built a 310 cubic foot concrete ib.


Other downside is you need double the subwoofers of a ported for around a same spl using the buttometer to test.


Upsides are no rearwave coloration so music movies sound clear and clean.
No blown subwoofer worries since no port to unload.
Low amplifier power required .
No fiddling once built. So perfect for absent minded me.

Yamaha avr, diy l c r surround Behringer nx3000 dsp Fi car audio ib318 v2 310 cubic foot concrete ib lg pf 1500 projector.steren projector mount at diy 135 inch screen triple 15 boss build .
Pending buy fourty 6 inch drivers for some new mains new 4k projector 1240 cubic foot ib for 16 fi car audio ib318 v2 subwoofers 4 nx3000 dsp
Russell Burrows is offline  
post #17 of 201 Old 07-17-2019, 02:57 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,272
Mentioned: 322 Post(s)
Tagged: 0 Thread(s)
Quoted: 3790 Post(s)
Liked: 3759
I picked up about 12-13db going from sealed to ported at the tuning freq. Enclosure size should be larger for the ported enclosures for more output. Sealed comes nowhere close to ported.

You can see modeled vs measured here:

https://www.avsforum.com/forum/155-d...ted-build.html

Stronger motored drivers will do better in ported enclosures.
monty6400 likes this.
notnyt is offline  
post #18 of 201 Old 07-17-2019, 05:07 PM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by notnyt View Post
I picked up about 12-13db going from sealed to ported at the tuning freq. Enclosure size should be larger for the ported enclosures for more output. Sealed comes nowhere close to ported.

You can see modeled vs measured here:

https://www.avsforum.com/forum/155-d...ted-build.html

Stronger motored drivers will do better in ported enclosures.

Hmm- reading your thread now- I dont/havet heard mine bottom yet- and i have NO HPF, and ive gone to -10 and the room shakes all to hell. Never even seen my woofers go nuts either unless im playing "Bass I Love You" at -10/0 I may pick up a couple sheets of MDF and try ported 34'HX20"W20"D
Remy.Alexander is offline  
post #19 of 201 Old 07-17-2019, 05:08 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,272
Mentioned: 322 Post(s)
Tagged: 0 Thread(s)
Quoted: 3790 Post(s)
Liked: 3759
Quote:
Originally Posted by Remy.Alexander View Post
Hmm- reading your thread now- I dont/havet heard mine bottom yet- and i have NO HPF, and ive gone to -10 and the room shakes all to hell. Never even seen my woofers go nuts either unless im playing "Bass I Love You" at -10/0 I may pick up a couple sheets of MDF and try ported 34'HX20"W20"D
10k cubic foot room on a slab takes a lot...
Trimlock likes this.
notnyt is offline  
post #20 of 201 Old 07-17-2019, 05:28 PM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by notnyt View Post
10k cubic foot room on a slab takes a lot...
I can imagine lol--Your room bigger then the house I rent,,,,, Our "family/Theater" room is like 13'X12', I hate being poor(ish)

Maybe the issue i had was i used the same 4.2Ft as ported with large port as per winISD- I just want to keep my 10/15hz
Remy.Alexander is offline  
post #21 of 201 Old 07-17-2019, 05:38 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,272
Mentioned: 322 Post(s)
Tagged: 0 Thread(s)
Quoted: 3790 Post(s)
Liked: 3759
Quote:
Originally Posted by Remy.Alexander View Post
I can imagine lol--Your room bigger then the house I rent,,,,, Our "family/Theater" room is like 13'X12', I hate being poor(ish)

Maybe the issue i had was i used the same 4.2Ft as ported with large port as per winISD- I just want to keep my 10/15hz
Make your enclosures large, tune to about 15hz. Simulate what changing enclosure size does.
notnyt is offline  
post #22 of 201 Old 07-17-2019, 06:11 PM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by notnyt View Post
Make your enclosures large, tune to about 15hz. Simulate what changing enclosure size does.
Here is model - Orange is how I run my sealed now other is massive 13ft with 27HZ HPF because excursion is evil with 500W, If i drop to 250W SPL sucks vs sealed

I dont want to go W or D, so H is the way. max I think 6'.
Attached Thumbnails
Click image for larger version

Name:	i cant model.PNG
Views:	50
Size:	55.2 KB
ID:	2592044  
Remy.Alexander is offline  
post #23 of 201 Old 07-17-2019, 06:56 PM
Advanced Member
 
SpinMonster's Avatar
 
Join Date: Apr 2014
Location: Colorado Springs, CO
Posts: 963
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 498 Post(s)
Liked: 304
Quote:
Originally Posted by Jedi940 View Post



The difference at 20Hz is 109db vs. 102db in the sealed. This is the benefit of a ported box. More around the tuning frequency. The "cost" is the bigger box size.
One thing that the above graph isn't showing is the far lower distortion you get because the ported box reduces excursion at all of the reinforced frequencies. At 20hz you are getting 7db more which is tremendous but the excursion may be reduced so much that distortion goes from 30% down to 5%.

By the way, in this graph the sealed and ported have the same output down to 13hz or so

Data-bass has subs tested that can be used ported or sealed and the distortion numbers on the sealed are far higher.
Remy.Alexander likes this.
SpinMonster is online now  
post #24 of 201 Old 07-17-2019, 07:00 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,272
Mentioned: 322 Post(s)
Tagged: 0 Thread(s)
Quoted: 3790 Post(s)
Liked: 3759
Quote:
Originally Posted by Remy.Alexander View Post
Here is model - Orange is how I run my sealed now other is massive 13ft with 27HZ HPF because excursion is evil with 500W, If i drop to 250W SPL sucks vs sealed

I dont want to go W or D, so H is the way. max I think 6'.

Doing it wrong.

an RSS390HF will tap out excursion wise with 250w in a 4 cuft enclosure sealed.

Here are the models for what you're doing.

250w applied to both
blue - sealed 4ucft
green - ported 12cuft 16hz tune 6in port tube 4th order bw highpass at 13hz

spl


excursion


port velocity
notnyt is offline  
post #25 of 201 Old 07-17-2019, 07:32 PM
Member
 
Audiophile75's Avatar
 
Join Date: Feb 2018
Posts: 166
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 123 Post(s)
Liked: 56
I started with two of them each in 8cuft ported tuned to 18hz and powered at 550w and I “thought” that they were pretty awesome as well. Man, was I wrong. THEN I found this...... (same 15”HF BTW)
https://www.avsforum.com/forum/155-d...topics/1329971

And then built them in a corner and common loaded them like this .....
Click image for larger version

Name:	5B1A8366-198D-4E65-AF58-C0A3CC86BC05_1563416888182.png
Views:	41
Size:	16.4 KB
ID:	2592068

I sure wished I did it sooner, but on the flip side I got to learn what I though was great was not. Did I loose a little low end? Yes, but I gained spl and lower distortion (The drivers were happier) at the very same power levels. Do I miss the low end compared to the spl? No way. Spl cannot fix everything but having uniform bass at any level is far more important for me. There’s something to be said when your friends sit down next to you on your couch and you can see their mouth moving like they are trying to have a conversation but all you can hear is pure loud bliss of music coming from your speakers at extreme levels.

Last edited by Audiophile75; 07-17-2019 at 07:40 PM.
Audiophile75 is offline  
post #26 of 201 Old 07-17-2019, 11:11 PM
AVS Forum Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 21,213
Mentioned: 854 Post(s)
Tagged: 1 Thread(s)
Quoted: 2950 Post(s)
Liked: 3678
+1 to not's post above. i was just going to post similar data.

max output of two hf's (with xmax set to 18mm for both since i think 14mm is overhang only).

ported is twice the size 16 cubic feet tuned to 16hz, 2 drivers.

sealed is 8 cubic feet, 2 drivers.

ported picks up around 12db max output in the neighborhood of the tuning frequency.



what doesn't show up on these graphs is vibration through the floor. if on a lossy floor (or riser) the ulf can cause some shaking of the floor that some folks like.

being smaller, sealed have a placement advantage in some rooms.

smallish sealed can require 2-4 times the amp for the same level of output in the region around the ported's tuning frequency because the ported has much higher sensitivity in that region. each 3db of efficiency requires twice the amp power. that can lead to properly powered sealing systems costing quite a bit more.

a lot of folks questioned how important efficiency in the bass is until 'not upgraded from 8 lms sealed with gigawatts of power and even he reported a noticeable increase in the sense of low-end power in his system, eq'd the same as it was to his sealed rig.

so, very roughly speaking:

lossy floor/riser, cost not so important, space at a premium and/or small room with a lot of room gain, proper amp power and eq, sealed can be a good choice.

lossy floor/riser or solid structure, bang-for-the-buck more important, size not as important, medium to larger rooms, lower cost amps possible, ported can be a good choice.

---

ported horns take it one step further if size is REALLY not as important. :-)

all this assumes reasonably well designed examples of each type.

if going for sealed, give nearfield subs a try (sub located right behind the seat facing into the seat). some folks like that experience as well.

i typically suggest to folks to get their output first, then go for extension second. that typically makes for a more 'fun' system.

they can all work. pick what you like!
Attached Thumbnails
Click image for larger version

Name:	1.png
Views:	275
Size:	12.8 KB
ID:	2592092  

Listen. It's All Good.

Last edited by LTD02; 07-17-2019 at 11:25 PM.
LTD02 is offline  
post #27 of 201 Old 07-18-2019, 07:08 PM
AVS Forum Addicted Member
 
BassThatHz's Avatar
 
Join Date: Apr 2008
Location: Northern Okan range (NW Cascades region)
Posts: 10,787
Mentioned: 233 Post(s)
Tagged: 0 Thread(s)
Quoted: 3762 Post(s)
Liked: 4269
The oversimplified short-answer is:
If you care about 1-15hz then go sealed/IB, if you care about 15-30hz go ported/horned.

The longer answer is:
There is no such thing as the perfect box. They are all trading something for something else.

IB and Sealed is great for small spaces, or a simplistic design (or if your goal is flat-to-3hz with a zillion cones.)

I would say that if the cone count is low, ported or horned makes MUCH more sense because you won't have enough displacement to make the 1-10hz usable anyway. Or if you don't care for XLF and are fine with only ULF.
Or in Not's case where the room is barn-sized, and the subs are 15ft away and the floor is concrete and adding more LMS-18's being cost-prohibitive (and now impossible, as they aren't made anymore.)

The main downsides of ported is the 12 or 18db/oct HPF, and chuffing at high-spl and the phase issues near tuning.
The latter only being problematic if that is the box-type you are using for an MBM (at say 50hz) and only when not using multiple subwoofers in a 2-way subwoofer design. i.e. Phase issues at the end of the covered spectrum is moot (but everywhere else, it is...)

Sealed systems obviously never have chuffing + cone distortions, only just the cone distortions.
Sealed and IB tends to suffer from a lack of 15-30hz, and bottoming and overheating. The increased excursion per watt increases distortion for a given SPL. All of this can be solved by adding more of them, until you have sufficient headroom. (But that of course is costly and inefficient...)

IMO I'd take 32 sealed subs over 32 ported subs any day, because 1-10hz is extremely important to me. I don't want to be down -48db @ 2hz, I want it to be as extended as possible. To me movies and basshead music sounds boring and wrong without single digits, it just sounds "thin" (like using a speaker set to small instead of a large speaker set to full.) But that's just me, everyone has different priorities and tastes. I understand that not everyone can afford 100kW and 32 subs, of any diameter... and not-everyone wants that much regardless...

If everyone were the same, the planet would be hella-boring. (Without bad people, Batman is just an unneeded clown in a rubber suit... )

I must say though... the GHorn is one of the better 15-30hz "fart cannons" available, it still occupies the # 1 spot for the loudest single 18 @ 16hz on data-bass. That's why I modeled the HzHorn after it, it's not the most musical sub between 80-300hz, but it is loud and fun where it counts (and a pair can just-fit in my space ).

At the end of the day, it's your money and your system, spend it or save it however you desire most. i.e. do whatever makes you happiest. Life is too short not to. We can't take any of this stuff with us when we're gone.
Better to have done a 100 years of trying and failing, than a 100 years of doing nothing!

Last edited by BassThatHz; 07-18-2019 at 07:19 PM.
BassThatHz is offline  
post #28 of 201 Old 07-18-2019, 09:44 PM
AVS Forum Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 18,627
Mentioned: 135 Post(s)
Tagged: 0 Thread(s)
Quoted: 2495 Post(s)
Liked: 2550
It depends on the ported tune, you can make big boxes and tune very low. If I can pull up photobucket I can show my speclab graphs of the same scene sealed vs ported. The ported only dropped below 3hz but had much more spl above 4hz. Mine were tuned very low.

Nothing right now
MKtheater is online now  
post #29 of 201 Old 07-19-2019, 10:36 AM
Member
 
drewp29's Avatar
 
Join Date: Mar 2010
Location: Southern Colorado
Posts: 151
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 63 Post(s)
Liked: 60
Quote:
Originally Posted by Audiophile75 View Post
I started with two of them each in 8cuft ported tuned to 18hz and powered at 550w and I “thought” that they were pretty awesome as well. Man, was I wrong. THEN I found this...... (same 15”HF BTW)

I built a Cinema F20 for my 390HF as well, and am pumping at least 900W into it. I don't run a high pass (currently), and that little driver hasn't given up the ghost yet! Plus I tickle the clip light on my PLX3002 regularly, lol. IMHO, the F20 is the best thing to use a 390HF in if you can deal with the size of the box. I considered building a 2nd F20, but am hunting for single digits now, and attempting to test the structural integrity of my house - according to the girlfriend anyway...
drewp29 is offline  
post #30 of 201 Old 07-19-2019, 06:43 PM
AVS Forum Addicted Member
 
BassThatHz's Avatar
 
Join Date: Apr 2008
Location: Northern Okan range (NW Cascades region)
Posts: 10,787
Mentioned: 233 Post(s)
Tagged: 0 Thread(s)
Quoted: 3762 Post(s)
Liked: 4269
Quote:
Originally Posted by MKtheater View Post
The ported only dropped below 3hz but had much more spl above 4hz. Mine were tuned very low.
So says the guy who switches box-types faster than some switch underwears...
So says the guy who switched over to an IB (and now enjoys that config better, as per his own words.) hehe!
I may be a mandela alzheimer recoveree, but I don't forget THAT easily (yet!)

Many moons ago, when you said your current config is "better", care to elaborate on that? If LLT is so spectacular with the SPL etc, then why ever switch? You are making us second-guess statements here. hehe!
BassThatHz is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off