Why Don't We see more LARGE Sealed Subwoofers?

With more and more 21- 24" subwoofers becoming available, why are people still porting them? Is it possible that by taking a large 21" subwoofer and putting it in a sealed box, that you can make a smaller box than a ported 18" and get just as good if not better low end extension? That is exactly what we will be talking about today.
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[@Toid]

A quick note. A 2’ x 2’ x 2’ box externally is 8 ft.³ however we care about the internal volume. When you calculate using three-quarter inch MDF with a double front baffle, the internal volume is 6.372 ft.³ once we subtract for bracing and subwoofer it is closer to 6 ft.³ I’m sorry for the confusion, I completely skipped over that.

[@Toid]

It seems some people are confused about the linkwitz transform. That is not EQ that’s being added, that is simulating the organic gain that we will receive via the room. This is called room gain. The linkwitz transform is just helping you visualize how that subwoofer will react in your room. So no, this will not affect excursion. If you want to know what the excursion will be, you need to look at it without the linkwitz transform applied.

[@zackolthoff4470]

@@Toid affect

[@AwesomeSauceShow]

I always wondered if the internal bracing is being considered in speaker design, actually asked about it on several channels, but here you clarified something that was nagging me for a long time. Thank you! I also wonder if we diy-ers can get close to the REL 1510 sealed sub performance (quickness),... Would love to see a head to head of your 21'' beast with them.

[@briantracy1324]

It sounds like this would be ideal to build into a boxed section of wall cavity if you have a dedicated home theater room.

[@evilinside5984]

By earthquakes slaps passive radiator calculator, 6cubes net, using 2-15 inch v2 slaps(these have 112.5mm=4.5inches of total XMAX!) would tune to 20Hz! They also recommend powered subwoofer forwards, and slaps mounted on back panel, loading off the wall, for best performance.

[@TokeBoisen]

I had this exact process with my (smaller) 15" sealed boxes. Some notes and pitfalls: - In my room, the Fsc for my subs is somewhat more resonant than what WinISD comes up with. - Erin's room-gain simulation assumes a 100% sealed room. Most likely not the case, so you might see a steeper drop-off or less flat response at the lowest end. - Remember that WinISD does SPL simulations at 1 meter, anechoic. You will most likely see 4-6 dB higher in room due to half-space or even quarter-space loading in corners.

[@JoelHernandez-tz3vk]

I can probably add another pitfall here. In my house, no matter where you go, there are windows... which also means there's glass everywhere. So it's physically impossible in my current house to have a truly bespoke home theater. But it was, at least by US standards, dirt cheap so we didn't have the luxury to be picky. On that 3rd point however, I assume you fix that mainly by installing more than 1 subwoofer. But I always wondered. How many subwoofers do I need?

[@TokeBoisen]

@@JoelHernandez-tz3vk multisub is generally about more even bass across seats or a larger area. For most people you can get decent bass across a row of seats with two subs. Most research conducted into the matter suggests four subs is the most you need before diminishing returns kick in, even for listening rooms with several seats. With regards to SPL, you have to factor in the air volume of your space and figure out what SPL you want to hit, to determine how much subwoofer you need. In most rooms, unless you stack the subs on top of each other, every doubling of the number of subwoofers results in 4-5 dB more output. So if you have a truly large room, it's probably easier to get bigger subs than more.

[@JoelHernandez-tz3vk]

@@TokeBoisen I've always read on several articles that I want anywhere between 2 to 4 subwoofers. The when I use 2 and when I use 4 is the not so clear part.

[@TokeBoisen]

@@JoelHernandez-tz3vk there isn't really a situation where four subs aren't better than two, but there might be situations where more than two is overkill. Rule of thumb is two subs can help you even out bass for a row of seats. Four subs will help you even out bass for several rows. But four subs will also get you more even bass for that single row, if that's what you have.

[@DIYAudioGuy]

That is going to be epic.

[@Hexen525]

I have a Skar EVL-18D2 in my vehicle. Had it in a 4.5cu ported box. Loud, boomy bass. Pulled it out, placed it in a 3cu sealed box. Tighter, more controlled bass. Not going back to the ported again.

[@mkshffr4936]

Twin 15s or 18s are probably a more practical approach especially since there would be far more drivers to choose from. My design approach would be to shoot for f3 right about at the room gain turnover point and a total system Q from .5 to .8. that way no mucking about with eq would be needed.

[@Pedrodemio]

This is a really nice way to setup a sub I have a 12" in a 40 L sealed cube that is barely bigger than the driver and it plays down flat to 105 dB @ 20 Hz and even goes up to 110 dB @ 10 Hz with barely any EQ due to my quite small room

[@TechEtrix]

Could you provide some more technical info on your sub? This sounds super interesting! I just got my hands on an SB2000 from SVS and yours appears to be having at least similar performance

[@Pedrodemio]

@@TechEtrix sure, just let me know what else you wanna know It’s a 12” Sub by a Brazilian brand called Questo, sadly they aren’t in business anymore, but parameters are similar to what you can find in good quality subs Amplifier is built in and it’s a P68 from Rod Elliot that I’ve built many years ago, and for DSP just a MiniDSP 2X4

[@TechEtrix]

@@Pedrodemio Thanks for the fast reply! Also, those are some great specs! Sadly would be extremely costly to build in germany. Guess I'll remain good to go with my SB-2000😂

[@seangarrison3515]

This is a very helpful and informative video. I've always wondered about room gain and how to calculate it. Can't wait to see real world tests.

[@michaelhosack6718]

I own a sealed subwoofer (only 12" driver): SVS SB-1000. It works great in small to medium living room. According to manufacturer specs, its frequency response is 24-260 Hz +-3 dB (2-meter ground plane, quasi-anechoic). Based on measurements with a microphone in my old living room, it reached 20 Hz with only about 2dB drop off. There was a huge room gain peak at around 40 Hz that I had to EQ down. The PB-1000 model is ported and is spec'ed down to 19 Hz, however it weighs 46 lbs. The SB-1000 only weighs 27 lbs. For music, I don't see any point in the ported model unless the room is large. Room gain makes a huge difference.

[@Elliott-Designs]

Amazing video as always! Looking forward to seeing how the subs perform in room!

[@Bassotronics]

Instead of using a Midbass woofer, how about using a car audio subwoofer? I know the efficiency is not as good but the T/S parameters for car audio subs supposedly does not correlate and the performance can be quite surprising. A JL Audio high quality subwoofer would be interesting to test with.

[@michaeldougherty6036]

I've always had a pretty good ear for good audio. But watching your video, and all that spreadsheet math makes it clear that I still know very little about the true finer points of being an audiophile. Great stuff!

[@Audfile]

I love my ported RSL Speedwoofer mk2. They are so tight and precise and keep right up with my CSS 1TDX Superiors.

[@Pentenfi]

I am looking so much forward to this! I live in an apartment in a German city so all my builds have to be rather small. For subs it's something like 10" ported, 12" sealed, dual 10" sealed...this is as big as I gets for me (it's enough though). Still I'm dreaming of builds like yours!

[@mikeortiz2139]

I think I'll be fine. Currently building dual 15" HO seal subs. My room is 10x12x9. Planned amp is one Crown XLS 1002.

[@EveryDayJay415]

Would love to see a micro cube 18” sub build I have my ultimax 18s in the 4cf flat pack but wonder if they can be built smaller with similar output/vs ported .

[@Clobercow1]

These larger PA speakers tend to be pretty stiff. You'll need to do some algebra to determine if this will work well or not. So you'll need to calculate the apparent power vs real power. This is where you look at the VA (wattage for AC current), and compare it to phase the coil phase angle, and do some math to see if this higher sensitivity is really giving you what you need to get the results you want. Note, winISD doesn't do this calculation. What I think you'll see is that as you try to get this driver to use its excursion, you'll find that the driver tends to get more and more stiff so the low end you end up with will be lower than you think. That's will a very strong BL. This particular driver has a very low motor strength for it's size and a fairly high QTS. This is sort of an advantage that we don't see with other 21" drivers and I think it's important to discuss that. Someone may take the PE 21" PA woofer and toss it into a box and think they can do this, and, the results may not be what is expected. This is why these drivers are typically ported. Their natural roll off as they play lower may be a bit more sharp than expected. Another note is that the sensitivity number, is not to be mistaken with efficiency. The primary limiting factors for sub-woofers output in the lower octaves is displacement and power. Most woofers are no more sensitive at 30hz than any other woofer. I've modeled many and I was surprised to find this to be true in may cases.

[@Nonamehere1]

Thanks for the comment, a lot of knowledge between the lines.

[@anandshah71]

Hi Buddy you are the person I need help. Can u help me design subs I don’t understand parameters and software

[@Clobercow1]

@@anandshah71 My best advice is to watch this channel, and DIY Audio Guy, and start doing some reading on those parameters and what they mean.

[@EBMproductions1]

@@Clobercow1 So what your og comment means is if you want 30hz or lower go for a sub built like a car audio sub or home audio sub and not really a PA sub? But also is the sensitivity deal the same at 40hz or are pa woofers better at 40hz n up due to pa woofers builds and nature? Asking as i want to run 18 inch pa woofers as my home audio subs and in a car to annoy a few spl guys but the goal in spl will be 45hz to 55hz burps not musical and low.

[@mastervang2058]

I've always that wondered about subwoofer sensitivity. Is there a set frequency for subwoofers when measuring sensitivity? Let's say a both were measured at 100 hz, wouldn't you get two very different numbers if you used a car audio subwoofer which was designed to play low but with but has less sensitivity compared to a pa speaker which cannot play very low.

[@genebrugnoni2784]

Im excited to see how this works out.

[@davemartin9912]

"I dunno" says the guy that has 4 18" Bag End S18E subs and an ELF-1 integrator anchoring his listening room. I developed a love for sealed enclosures when I lived in an old ranch house that had a mouse problem. :-)

[@willbrink]

Personally, I prefer sealed subs vs ported for music. Ported subs are great to go thump thump for HT, none I have heard didn't sound like mush for tight fast accurate base for music. I know ported subs have gotten better over the years, but musical subs from companies like Velodyne are my choice. I wish I had the skills and patience to DIY a good sub!

[@GTILOUD]

Are you into car audio at all? I’m designing a box for nine 12” subs all separately chambered sealed.

[@abelcanahui3459]

Why did you choose the Rosso 21s for this sealed box? Just trying to explore your track of thought in this build to learn. Thanks!

[@mullinperformanceaudio5902]

This is what I'm jealous about with home audio guys. They make any size enclosure they want. Lol

[@Toid]

That’s funny, because I was thinking the same thing with car audio guys lol

[@Enlightenment_2025]

Oh, I envy both of them.

[@jukkamaljanen6644]

Thanks for the vid! I'm facing this same question right now, but for a smaller driver, a woofer for a 3-way build. One thing that is possible with a dsp processor, is that with playing around with the pole frequencies of Linkwitz transform, you should be to EQ it quite flat to 10 Hz with just one filter. Port tuning is after all one form of "analog", acoustic EQ. Anyway I'm highly interested in the outcome and sound comparison of the two box types, so please hurry with the construction! 😉👍

[@jimthvac100]

I confident your idea will work. I never considered using DSP for controlling the base for a subwoofer. I don't have the equipment to test something like that. I need to do some research into some that might be affordable. I also was going to build some efficient speakers that use one of the 15" Lafoce woofers but decided a larger 18" Lafoce SAF184.03 could go even lower at the same price and slightly smaller cabinet. I want to use it in a three way build with a Eminence Alpha-8MRA 8" sealed back midrange, and the Selenium D220TI 1” Driver you used in a previous build. crossing at 450Hz and 1500Hz. This should give nice dispersion and should be good to about 39Hz 3db down with an internal volume of 4.3 ft3.

[@Toid]

That sounds like a really nice build!

[@tweakerman]

Love your channel, it's really informative, & you do great speaker build👍

[@Toid]

Thank you

[@audfrknaveen2256]

Eagerly waiting 😀😀😀 just yesterday I finished building one 18" ported sub

[@Toid]

Nice!

[@audfrknaveen2256]

On internet there is not much one to one comparison between Ported Vs Sealed with EQ. For example if a ported sub is tuned to 20hz F3, with the help of EQ, Sealed sub should also be tuned to 20hz F3. And compare both subs in a single room, at same locations. Both subjective and objective measurements at same listening position. And then subs at near field, and also very near field(just behind the couch, to observe tactile feel)

[@mantaproject]

Thanks for doing this, I was thinking of the same question but there's nothing about it on the internet.

[@fookingsog]

Sealed, alternatively termed "acoustic suspension" would probably be the best option, especially if the amplifier you're driving it with doesn't have a very good "damping factor"!!!

[@Pgr-pt5ep]

The bigger the cone area, the stiffness of the cone needs to be exponentially greater to compensate for the cone distortion. The problem is amplified when the backpressure is greater as in a sealed enclosure.

[@analogkid4557]

Awesome! Going to check these drivers out.

[@ajc-th5ei]

Great video. Quick note: having a linkwitz transform can reduce the amount of watts you can feed into the subwoofer. You might want to check that due to excursion limits. I noticed that with modeling a Kracken 21"

[@Toid]

Great point, the linkwitz transform is just simulating what we might expect out of room gaIn. It won’t actually be applied to the eq.

[@ajc-th5ei]

@@Toid i think miniDSP has a spreadsheet for coming up with the values to enter into their DSPs. So trying the linkwitz transform with the miniDSP 2x4 HD, if you still have it, might be fun to compare.

[@Pentenfi]

@@ajc-th5ei He uses the Linkwitz Transform to simulate room gain. Erin from Erin's Audio corner made a video about this. Room gain behaves ideally like a Linkwitz transform from the lowest room mode down to 1Hz. Of course, in reality it differs. He didn't simulate a DSP setting primarily.

[@ajc-th5ei]

@@Pentenfi -yeah, but I'm thinking more on how to use a linkwitz transform to obtain the low end extension, then correct aberrations with other filters, and get lower at the cost of sensitivity due to excursion limits when using LT. But your point is well taken on this simulating room gain.

[@Pentenfi]

@@ajc-th5ei I haven't tried any LT yet, but it's also on my to do list. I think your approach will work well

[@michaelcorlet2998]

Very informative.thanks.

[@stefanweilhartner4415]

i prefer to not have the same dimensions in every direction of the box to have separate resonance frequencies. you could also use the golden cut ratio to position the driver more up on the front and not in the middle. this way the reflections come back to the driver at different points in time and affects different frequency ranges but with lower intensities. close to the bottom you could add a horizontal piece of wood with a hole in the middle and this small chamber is filled with two different absorber materials to kill the standing wave. between the two damping materials essentially a reflection barrier is being created where a few percent gets reflected upwards. this way you disrupt the standing wave and it gets partially absorbed.

[@patrickbennett439]

I got 2 skar EVL 18s in a slightly oversized sealed box, best skv2 4500 skar amp, 320 alt, 0 guage, lithium battery. Shakes hard and hits pretty low for a sub with a 32 hz FS. I typically like a lower FS sub, I learned about FS after buying the EVLs. I had an L7 kicker 15 with a lower FS and it had a different sound sealed. It was like looser or sloppier than the EVLs. The EVLs shake very hard though at high power.

[@evilinside5984]

@patrickbennett439- What was the net cu. ft., that your sealed enclosure was for your kicker L7 15? Did it hit the 20s to 30s hertz freq., better than the 50s to 60 hertz freq.? Also, what is the net cu. ft., of the sealed enclosure, for your pair of skar EVL 18s?

[@patrickbennett439]

@@evilinside5984 EVLs have a 4 ft cubic area per sub. My L 7 only had like a 3.5 ft I think. Its close to that and its not the max for that sub. SOmehow that sub still did just fine. Back in the day with that L7, i never really tested it on exact hz levels. I just played chopped n screwed albums and it hit low. I still have that L 7 in storage. My EVLs still shake my truck on a 18 hz test track, but its not loud, just shakes a lot. It started picking up volume at 22hz. 28 hz it hits with ease and loud. People complain about how 18s dont hit highs, mine do pretty good but not like 10s or 12s. Most my slowed rap still isnt much below 25 hz and the EVLs do it well. Theres a few songs that a ported box might get that 22 hz louder on, but whatever. Sealed is king and I dont really give up much lows at all. 18s get it either way. Since volume isnt an issue, I love quality. Still hear me knockin from blocks away. People say they can feel my bass when i pull up near them and thats that sealed bass shake they feel. Ported boxes shake cars while sealed somehow shakes people better, so less rattle and all the earthquake. Metal moves with the slower bass waves from ported boxes, not good in my opinion and Ive had both. I like tons of power and use more subs than boxes. A port is about equal to another sub so I just go with subs and not ports. One day, the stereo realm will figure it out, but right now we live in the age of ported.

[@evilinside5984]

@@patrickbennett439 - I have been a Car Audio competitor for over 30 years. I also have designed and built subwoofer enclosures. I love the sound of sealed subwoofer's. But the trick to get the most low freq. output, is to go Large= 2x + on the Mfg. Rec. Sealed specs. Like about 7 cu. Ft. Per EVL 18". If you would like to see how it would sound, just pull 1- 18" out, and if your enclosure has a center divider, just cut out a 12" hole or so( big enough, but not so big, that you can't fit a pc. of wood through your subwoofer cut out, to be able to cover the hole in the center divider, should you want to go back to 2-18"s, in 4 cubes each), then just put a pc of wood over the 1-18" hole you took out( use a foam rubber gasket, or RTV silicone if on a wood box), around the 18" hole before covering it, to seal it better. If enclosure is carpeted, it should be fine as is. Drive around playing itlike this to see if you like this sound= should be more Low freq., and Less 60Hz+. Remember though, as far as out put goes, it will be half cone area, and half power, this is just to see if you like the Sound better. Then if you do, you could just make another enclosure the same specs, and have 2- separate enclosure's, or Build a whole new enclosure, the size and shape, that will fit/work for you. I have 4-18" in approximately 30 cubes, and they sound Amazing!

[@patrickbennett439]

@@evilinside5984 Id like to hear that. In my experience with systems, theres very little over sizing a sealed box because, Ive taken ported systems and sealed em to see how that sounded and well, it just worked the woofers to hell and i had to re glue them. They didnt blow but it wasnt really better sound than just a slightly oversized sealed box. You can loose loudness with too big and over extend woofers, but sounds like you got that to work for you. Awesome. So my box is slightly oversized per sub according to specs and they hit low as shit. Im curious if I went a tiny bit bigger, that might still work. My woofers jump so dam far though right now.

[@evilinside5984]

@@patrickbennett439 - Yes, a much bigger box= much less mechanical power handling. I forgot to ask how much power you are giving your Skar EVL 18s, amp model, and wired impedance? Oh, and my enclosure for my 4-18s, i designed to be able to have 4 different tune/set ups. 3- Big Aero Ports, and i can block off the ports 1 @ a time to change tuning freq., as well as block them all off, and run them sealed. My 18s have 4 inch coils, that i have put 5,500 watts RMS, as clamped using the term lab power probes, on 1 subwoofer before, without a problem. They have over 4 inches= over 100 mm of peak to peak excursion, with an Fs in the 20s, they sound Amazing, and detailed. With the power ive got to use, they will do over 150 Db, @ 18 Hz, in a No-Wall set up, in my SUV! I won a Champion Ship Ring, for highest, Low Freq., Musical Average.

[@skallywagzzz]

Now that this is 2 years Old would you amend anything? different driver etc? Also would a Behringer NX6000D be a sufficient amp for this? its the only well priced amp local to me.

[@Toid]

I wouldn’t. Every time I turn them on, I’m amazed. I love them. And yes an NX6000D would be more than enough.

[@skallywagzzz]

@@Toid Much Appreciated thank you for your prompt reply 🙏

[@FatFolksProductions]

I been watching so many videos on DIY. Not sure if i want to go sealed or ported. My setup is in a smaller room 12x12 which would you suggest? 50% Music 50% Movies.

[@bennyspieler528]

I have 2 Ultimax 18 in 4ft³ enclosures and they do about 105dB at 20hz. With dsp i got them pretty linear in my room. I am thinking about building mini marty enclosures for these two but actually its enough.

[@rickbutcher3459]

I built a 12cu box. Put r13 insulation in it on the walls. Does that effect the cuft?

[@asilva781]

I built two subwoofers for music my systems. I know the compromise of sealed boxes and as well both are isobaric. Yes, I know, very poor eficiency. But iI get a very clean musical bass perfect for music.

[@CoreMaster111]

My experience shows that if I ever build another sealed box then I need to build a big box and I need a subwoofer with a lot of power. Otherwise it's just underwhelming unless you want to use DSP to tone down all highs and pump up lows. Room gain may not add as much as you expect, especially good sounding bass but it's all different for various setups.

[@z1berzerker]

Curious to see this build 👍😎 wonder about Passive Radiation 🤔... Keep up the great videos 📹 👍

[@Toid]

Thanks Joseph. Tomorrow night me and DIY audio guy are going to go live and talk about sealed versus ported versus passive radiator. If you have any questions, you might wanna catch the live stream tomorrow. That way we know what we can answer.

[@z1berzerker]

@@Toid I will be watching 👀 😀 👍 for sure

[@hymugglee6236]

How much power should my power amp have for 2 "15 dayton hf in a HT setup in a large room 500sqft? I currently have 400wpc but it is not enough.

[@annihilationindustries1990]

Yah im not sure why almost all the subwoofer manufactures for car audio always has the sealed enclosure recommendations smaller than ported ! Like why would i want to jam to dubstep and rap with an estimated FS of 49hz for a 10 inch driver just because they say .5 cubes is ok 😅. Yah a bigger sealed box will handle less power because theres no ability to port load like a ported, but the drive would be more efficient, drop lower and the curve would be flatter than a small enclosures frequency curve .

[@cabasse_music]

awesome video. at first glance that sub was giving me serious PA driver vibes with its seemingly stiff surround, and i assumed it was going to have a much higher EBP than 47. is that a foam roll? i thought it was just doped paper at the edges. i am basically doing just this at a much smaller scale, with a cheap Saga Elite (SAG0207) in-wall sub - dual 8's of some glass fiber type in a very small (stud-depth) sealed backbox. instead of DSP i have a used DBX EQ, with the lowest frequencies turned way up, and it goes quite DEEP and much louder than i can use in my current space. planning to try to take it with me when i move into a real detatched house, it's too much for a townhouse and i don't even use it currently.

[@bikall1]

just build 2pcs 12 inch sealed servo subs. They go down to 15HZ and up to 200 almost flat no problem. Best subs i ever had.

[@JC-lk3oy]

I'm with you 100% on this. My Rythmik L12 gets down to 15hz without issue and is clean and clear throughout its range. Sealed servo subs are impressive.

[@bikall1]

@@JC-lk3oy mine are also rythmik. I tried to run them open baffle, but sealed has more output and suprisingly a flatter output. Combined with magnapan lrs.

[@JC-lk3oy]

@@bikall1 yeah, I know Danny likes to run his rythmik setups OB bit I've found the same as you. Without DSP sealed seems to go deeper and stays flatter.

[@ER-rt9le]

This video popped up in my feed. I got a good deal on 2 Bag End Infrasub 18s sealed subs. Just curious if these are considered good from a designers perspective?

[@garygranato9164]

looking forward to this

[@robotag95]

Hi. What speaker profile did you use for WinISD? Trying to design a box for this driver.

[@rare_grooves_shack_1983]

having not watched this video yet, I'm sure internal volume and cabinet size and resonances will be an issue, i wouldn't be surprised to hear that sealed airsprings are more likely to make larger surface area woofer cones more prone to flex, or requiring added bracing

[@jimbendtsen8841]

I love the Piggly Wiggly hat. There used to be one in Minnesota, but I don't think there are any here any longer.

[@7thsoneli]

Whats with the spam on youtube now??? getting messages from fake scammers in the reply's looks like almost every comment reply is sent a message for a gift,how do we get rid of this???

[@theno1deejay]

Great video. For me, sealed subs sounds more musical than ported. I can´t build myself so I use two Canton Plus C 12" passive subs.

[@kenwebster5053]

The explanation I have encountered for the past 50 years or so, is that speaker & box act like a tuned spring system, the speaker diaphragm being one spring & the effective box volume being the other. If you want to promote low frequencies, you have to get both these components tuned together. Now if the box is sealed, it's effective volume is pretty obvious, but that tends to lead to a rather large box volume for a given speaker. This can be awkward, especially for a sub as low frequencies require a larger optimal box than high frequencies, because of their wave lengths. However, putting a port in a box, makes it respond similar to (but not exactly the same as) a much larger sealed box. Therefore, using the same speaker a smaller ported box can achieve the same low end as a larger sealed box. From this, we can see that subs are pretty much all ported, because it allows a smaller box to achieve the desired low end response. However, in all this there are generally compromises, simply because there in no free lunch. The ported box tends to have less accurate fidelity & may have some dips in it's response curve that are not present in the sealed box design. This can be smoothed to an extent with cleaver design choices. Generally at the same tech level, a sealed box of appropriate design & construction will will have a more natural and higher fidelity sound than a ported box. There will be a difference in manufacturing & sale price for that though. Also, depending on your audience, they may or may not care about natural sound reinforcement, they may just want to party off to excessive bass. So, horses for courses as the saying goes. It has been said, there are only 2 types of music, Pub Music or Spiritual Music, or another way to look at it is Music Enjoyment vs Music Appreciation, the latter being transported by the sheer timbre of each exquisitely expressed note. Not everyone wants the same thing all of the time.

[@poleepwka]

I have done something similar. 18 " woofers in sealed case. The Faital 18XL1800 has a FS of 29hz and sensitivity of 95db .You plan to EQ the subs flat before putting them inroom. Currently I did not apply any EQ for the sub, but EQ the subwoofer inroom. Would there be a difference in performance?

[@Toid]

This theory, I was just seeing what the outcome could look like theoretically. But I will apply EQ only after I place in the room.

[@poleepwka]

@@Toid I had a Linkwitz transform, but it was way to boomy once I placed it inroom. Much better result with applyong EQ once in place. Looking forward to your findings and how it will correlate with my own experience.

[@captanspace]

My living room isn't closed, it has an access to my kitchen. Do I still have the room gain? Should I consider the distance from the living room wall to the kitchen wall or to the other living room wall?

[@Toid]

You do still have room gaIn, but it would be a lot harder for anyone to guesstimate it. I also didn’t talk about other gains like boundary gain that you can also get. Having said that, you could someone visualize the amount of gain if you had a measurement microphone. As long as you take a Nearfield measurement microphone of your subwoofer, and then a measurement again at your seating position, you’ll be able to see the gain you are receiving.

[@bellajay713]

Which would be louder at 25hz. A 12" sub ported at 25hz or a 15" sub in sealed box?

[@adddictionsGTP]

Interesting video. If it work’s in theory it should work in practice.

[@Toid]

Let’s hope so

[@chrisf7249]

I just put two eminence 18” sigma pro subs into sealed 3cf boxes. (2.3cf after deductions) Got them on a dbx drive rack and qsc 1850hd, and I just inverted the frequency response from one of these box building programs in to the eq. It definitely tightened up the base. I think I’m getting about 1/2 the volume of what I was with them in the bigger vented ones.

[@chrisf7249]

I’m not sure how to do that, but will look into it.

[@chrisf7249]

Just an update, I found a tone generator and used it to generate the lower 7 band frequency’s of the 27 band EQ built into the dbx to help adjust it. That sure made a difference also. Now the bass sounds pretty flat from 200-30hz.

[@datdudeinred]

Wait that huge dip in max power in 20cuft box was due to the driver having a huge qts right? not just because of size of the box? correct me if im wrong.

[@Toid]

It is due to the size of the enclosure. As you increase the size of the enclosure, the easier it is to reach the mechanical limits of the subwoofer. This is true for all subwoofers.

[@BlankBrain]

Surprisingly, a 15" driver in a 5½ ft.³ ported cabinet can sound very good. Two 4" diameter long ports result in controlled extended response.

[@Toid]

Yeah, I’m currently using the MX15 in about a 5.3 ft.³ box ported. This sounds very good I’ll be interested to see how much of a difference if any at all the 21 inch makes. Or said differently which one I prefer

[@BlankBrain]

@@Toid I reverse engineered JBL 4343s when they came out. My stepfather and I built a modified pair. I replaced the horn and lens for the compression driver with a Carlson Coupler called The Tube. I used a heavier JBL 2215A woofer. I never got the 2405 super tweeters. The Tube extended the upper range of the 2420 compression driver. I didn't feel competent to design a crossover, so I bought active crossovers and tri-amped. I borrowed an HP Wave Analyzer to tune the ports. I used 1" x 1" and 2" x 2' oak glue strips and crossmembers, which the originals don't have. Over 125 #10 screws in each cabinet. Parts of the cabinets are 2" thick to stop resonances. I just pounded on the sides and back to tell where that was needed. I used Wilsonart teak plastic laminate (similar to Nepal Teak) rather than veneer. It actually improves the sound quality. It's held up against moving, children, and parties. I really like the cabinet design that you came up with. The reinforcements are great. They would be labor intensive without CNC or some automation. Do you just make a template and use a router? I really appreciate your innovative work. stereonomono.blogspot.com/2012/12/jbl-4343.html

[@Toid]

@@BlankBrain that sounds like an amazing project. Definitely a labor of love. I’m going to have some plans available for this particular subwoofer box that will include all the dimensions for the braces. So, if you don’t have a CNC, you can cut them in the individual pieces if you have to as well, and all that will be in the plans. but the dimensions of everything will be there so that you can easily transfer it to a piece of MDF, and use whatever tools you have.

[@KidAgainHobbies]

i modeled this in winisd and the xmax is way over if you boost these frequencies. is this what happens in your room with these subs?

[@Toid]

You have to check the X max before you add the Linkwitz Transform. That filter just simulates the bass you’ll get by putting it in your room. Since you aren’t artificially boosting, it will not affect Xmax.

[@adamdjd7882]

Yo nick, can you make a video about the DSP section of this build? I’m new to the hobby of diy audio and see people adding filters on winisd, but I don’t understand how to practically implement them in the real world. I’m definitely going to build these beasts, watched the video about 10 times haha. Keep it up mate

[@iikatinggangsengii2471]

even i use it more than mine desktop

[@vader540is]

Power Sound Audio has been selling plenty of sealed 21inch subs ( B&C neo)

[@bikdav]

You need to do a comparison between sealed and ported.

[@mrboat580]

I could fit two sealed, vs one ported in my room in a music only system. Oddly enough, the bass in the music I tend to listen to ends up rolling off at about the same rate as these sealed subs do, anyway. A single ported sub ended up being in an awkward spot in the room that I would basically have to move it to for optimum performance, and then put it out of the way when not in use. Two subs ended up fixing more issues and being much more forgiving with placement and then there is the added benefit of stereo (left/right channel) subwoofage.

[@jeromelester8]

What about passive radiator?

[@blakebrockhaus347]

passive radiators would also be a good option. but all the 21" passive radiators I've found are $200+ so it'll more than double the cost of the sub

[@kingwillie206]

Try a passive radiator and get the best of both worlds. You’ll have a small tunable box.

[@royrodriguez4779]

Subscribed! You had me at “large sealed subwoofer” I was thinking of switching out my vented 12’s (pair) for a pair of sealed 18… 21 seems like overkill to me…. Though I’ll wait for your video to find out Anyone have a pair of sealed 18s that can share their 2 cents????

[@kevinb.8649]

I love the punch of sealed subs. Takes a little more power but sound quality and tightness of the bass can’t be beat. And radiators are kinda the best in between.

[@gravitystorm61158]

I’ve got a Polk PSW10 10” front firing with a front chuff port. Yep, it works… I’ve also got a Hsu VTF-2 down firing back ported huge cabinet. The Polk is speaker wire powered feeding a pair of Model 6’s. And the Hsu on LFE. On Carpet, the Polk sounds better. Put a piece of MDF under the hsu,, and the hsu fills my 2 story living room. But, I just got a Sunfire SDS10, haven’t had the time to play with it though. Just finished the burn in. But, I’d be down hooking up 2 subs on my theater set up. Both next to 1988 model year Polk RTA11TL’s. A Cambridge Soundworks “The Center” center channel 5 driver speaker, and surrounds are Cambridge Soundwoks Ensemble pair mounted to the ceiling behind the listener. In a 12X16 room. But my point is, “if you don’t mind a huge system and have the room, why not do 21”-24” subs? If your amp can push it.

[@iikatinggangsengii2471]

on good chain that should be my preferable as well, but lot of factors in chain that yeah, hard to explain

[@kurtbrisch5776]

YG Acoustics makes a sealed box with a custom built in house 21" driver machined out of a solid billet of aircraft grade aluminum alloy. On the down side it's cost more than most peoples cars.

[@danrussell9357]

The flow of the content is easy to follow. Please make a follow up video.

[@csj9619]

Such a large driver may not be necessary. The Emimence LAB-15 has been proven to go low, BUT the enclosure size may be larger than what's desired.

[@jsbrads1]

It occurred to me and speaker can have a microphone and when you place it, you can have it play a hertz scale and listen to the result and create sound for the current room with a bit of software.

[@zarboaudioprojects1430]

Coming from a stereo setup where my main listening room is sporting a 5.5" subwoofer, this thing literally scares me. I remember when a 12" sub was pretty cool and if you got a raise, you went for the 15" sub. What kind of world are we living in? :)

[@Toid]

That’s funny, I was just talking about that. If you had a 12 inch, you were rocking it now it’s kind of funny because it’s 21 inches basically the same price as the 18 inch Ultimax it’s really crazy to think about. 😱

[@shawnbrennan7075]

Genius! I'm surprized a pro sub has that low of an f3 sealed.

[@Toid]

Yeah, it’s actually really impressive. SB Audience sells a more expensive one, but does not model nearly as well. The crazy thing is it’s not that expensive either. It’s about $385. Which is about the same cost what is the ultimax 18 inch.

[@hadleymanmusic]

Port resonance;; flute the port with front baffle distance positioned in the proper spot inside the fluted end.

[@eliebreaux6504]

How's the build coming along? Really interested to see your real world results.

[@Toid]

The build video is up

[@eliebreaux6504]

@@Toid Yeeeeesssss.

[@GurvanBHC7]

Hey, someone can give me a winsd file for this sub? I can't get the "driver editor" to work for this sub, the parameter seems off...

[@Toid]

Try to input the values in this order kzbin.info/www/bejne/hZ2afGithtd5d8k

[@GurvanBHC7]

@@Toid Thank you very much i will try it. I need 4 sealed sub. Can’t decide between Ultimax 18’ or this 21’ from SB Audience…

[@GurvanBHC7]

@@Toid I tryed this, but nothing worked… This is the first time i failed to enter parametre on winisd

[@Toid]

@@GurvanBHC7 make sure you are inputting the correct units. Also check to make sure auto calculate is on and allow the program time to auto calculate by clicking a new field after your input, the data.

[@AllboroLCD]

Some say if your system is inclined for music, you do in fact want a sealed sub. Ported for those who are into theater/gaming. Ive been a bit curious on "dual opposed" sealed subs myself lately.

[@Toid]

Dual opposed is a great option. I almost considered doing that for this build. As far as why people say a sealed sub is typically better is due to the fact that it has a lower group delay. Wouldn’t be cool if we could keep the lower group delay and still get the extension that a lot of people want for home theater? that’s what I’m hoping for at least

[@AllboroLCD]

@@Toid I suppose thats where DSP comes into play?? DSP isnt completely shunned by the audio elite when used in the lower bass registers.

[@AllboroLCD]

@@Toid If you can find images, the Altec Lansing AHT 2300 sub is a very intriguing design for dual opposed. One of the first ever THX rated subs when the tech was licensed for home in the early 90's. Back when the rating actually meant something.

[@jordesign]

I have a dual opposed cube myself, and I love it, especially for music. It is a 14" cube, with two 10"ers...

[@littlewicky1]

@@Toid isnt that where servo subwoofers come into play? Rythmik sells their drivers and amps if you want to DIY

[@nearchd504]

I have a 18inch Lf Driver fitted into a ported enclosure. And now i have choked it's slot port and it sounds better inside room now In s sealed enclosure with the volume of a ported enclosure.

[@chrisharper2658]

Looks more like a regular woofer meant for large spaces than a sub-woofer to me. I'm no expert but looking at the Qts, wouldn't that be best suited for an open baffle design? In your small space, it sure will get loud.

[@dheepak10]

It will be interesting to see the final results. Powersound sells its S2112M secondary (without amp) for USD 1699 and Primary (with amp) for USD 2699. Enclosure size is very close to 6cu.ft as well; different driver though. Will be interesting to see the results DIY can achieve.

[@Enlightenment_2025]

Bigger is better. I tested my hearing on youtube. I could hear down to 50hz only. 30hz with headphones. 30hz response is good enough for me instead of 20 hz. All in practical terms.

[@lennart637]

Reminds me of the PSA S2112M, BetonArt Tyrone or Ascendo SMSG21. If the Q is high (0.8 and above) this wouldn't have a sonical benefit over a smaller (18" woofer) ported sub.

[@RobertCookcx]

Maybe a solution is to sacrifice the F3, preserve the sub's inherent efficiency, and augment the low-end (i.e,

[@Toid]

The reason why you can do this is because it is so sensitive. You’re still able to achieve more than enough SPL EQing it down. Could you do what you’re saying,? Yes. However you would have so much overhead that you will never use. Basically, the subwoofer is so sensitive, that you’ll never reach the max SPL of the subwoofer in a normal environment. I’m the end it just comes down to what it is that you’re trying to accomplish. In this case, I’m more than willing to sacrifice some of the sensitivity to get a lower extension…especially since I know that it’ll meet all of the SPL requirements needed. As far as the DSP goes, you’re going to need a DSP any subwoofer inside a room. So I don’t see the DSP being an issue.

[@earlfenwick]

Sorry to be that guy, but 2x2x2=What? Love your show!

[@jamesrobinson9176]

Lol +1

[@Toid]

A box that’s 2 feet tall by 2 feet wide by 2 feet deep. That’s 8 ft.³ external but the internal volume is what we care about. Using three-quarter inch material with a double front baffle you’re at 6.372 ft.³ once you add in the bracing and the subwoofer you’re right around six total cubic feet.

[@thirumalkumaran]

The logical explanation i think is removing brace volume and driver volume! could land up from 8 to 6!

[@Toid]

@@thirumalkumaran Ah, yes. Those are external measurements with a double front baffle using three-quarter inch material the total internal volume without bracing and subwoofer is 6.372 cubic feet. Once you add in the bracing and the subwoofer you’re closer to 6 ft.³.

[@earlfenwick]

Alles klar! Love you show!

[@Jonas_Aa]

Do you really need to brace the box that much when having low frequency? I thought bracing was more when you want to go higher in frequency. So basically you need to brace more to make the sides shorter to not have higher frequencies resonant the sides of the box.

[@dfgrow]

I think the speed of sound in fps is 1125.3 but great video

[@7thsoneli]

I use 18 inch skar in a 3 cube box with 6 an boost at 30 Hz

[@Dope.And.Pretty]

But is this a realistic gain? Sure a sealed box with room gain can perform similarly or perhaps even better to a ported box WITHOUT room gain, but a ported box gets room gain too, does it not? Then once you take that into account, you have an even louder (potentially better, depending on your proclivities) setup.

[@Toid]

It does have room gain, but not as much as a sealed subwoofer. You have two things going against a ported subwoofer. The first is that a ported subwoofer is going to drop off in frequency, adding much faster rate past port tuning. The second is that with a ported subwoofer you’re also going to have to put a high pass on to protect it past port tuning. This makes it unpractical that you’re going to get much gain past port tuning.

[@Toid]

As far as realistic gain, check out the build video where I ended up building these and testing the final response. kzbin.info/www/bejne/o36ad2majLKSmsUsi=V2Ou4TWYWAAosvkY

[@Dope.And.Pretty]

Why does a sub in a ported box have less room gain than the same sub in a sealed box? Shouldlnt you usually be looking for a sub that has the port tuned close to the lowest frequencies you're playing anyways? Most music doesn't play much lower than 30hz, I can't imagine wanting to play below 20.

[@Toid]

@@Dope.And.Pretty think you’re misunderstanding the issue. The difference is how quickly the base drops off in each system. Ported subwoofer would drop off 18 dB per octave. Sealed subwoofer only drops at 12 dB per octave. on top of that with a ported subwoofer, you lose cone control after port tuning. So you will need to add a high pass to protect the driver. That high pass will typically be tuning. If you plan to really push your subwoofers, then you’re going to have a very steep high pass. Think 48 dB per octave. That’s just to protect your subwoofer. With a properly designed sealed sub you don’t need any high pass. What does that mean? Well for those who want it, depending on the room, they can hit significantly lower notes. Know whether that’s important to you or not is another story. But a lot of people in the home theater environment are wanting to go as low as they possibly can with as much as intensity as they can. a fun visualization would be to download the free program WinISD. Model a ported subwoofer like the Ultimax 18 or 15. Tune it to 20 Hz, then go to your filter tab and put a high pass on it. I think you’ll get a better visualization of what’s actually occurring. And if you want to, you can put a curve very similar to what we did in this video on room gain. Then take the same subwoofer and put it in a sealed box with the same room gain, and no high pass filter. that way you can visualize the difference.

[@Dope.And.Pretty]

@@Toid My application is in a car, so no need to go that low. Will just be listening to music, which doesn't often drop below 30hz. The one huge drawback I do see with ported is it seems about impossible to get around chuffing without going to a very large/long port, which then takes up the whole trunk.

[@AndrewUnruh]

So the presenter has hit on something that many of us have hit on over many years. Short answer: it usually works. Long answer....it depends. A small cabinet at a given frequency and spl will always have a larger internal pressure swing than a larger cabinet. I had one instance where the internal pressure (and gage vacuum) inside the cabinet distorted the shape of the surround so much that at high sound pressure levels, a popping noise could be heard. On the other hand, I have been running a set of 15" JBL professional woofers in a small-ish sealed cabinet for years without any problems. BTW, here is a related question that I used to ask prospective acoustic engineers during an interview: You have two speakers playing at the same low frequency (wavelength

[@Oystein87]

Huh? Why we don't se MORE?👀 I see a kinda big selection bigger size subs in close enclosures on the market🤷‍♂️ All the way from small 6,5" all the way to the big 80" (80" membrane size, 100" screw to screw) Ascendo sub...

[@SageBlueMusic]

I need a smaller version of this with 70-90db 13hz bass lol.

[@audfrknaveen2256]

After adding parametric EQ filters, winisd shows cone excursion crazy high.

[@Toid]

Are you saying after adding the linkwitz transform? If that’s the case, it will be, but keep in mind, you’re not actually adding a linkwitz transform, you’re just simulating with the room will do organically. In order to look at the actual con excursion, you need to remove the linkwitz transform.

[@audfrknaveen2256]

@@Toid yes yes i mean the linkwitz transform. 😊😊😊😊

[@Toid]

@@audfrknaveen2256 yeah. If you take that off, you’ll see what the actual excursion of the driver is. We’re just using the link with transform to simulate the type of gain that you’ll receive in your room..

[@blueflame0003]

i got 2 18inch in a seal box...and that same company makes 21inch in a seal box PSA....

[@patrickbennett439]

Hell yea, im slammin 2 18s sealed box too. @ skar EVL 18s on the 4500 skv2 amp 7k peak or so.

[@fookingsog]

And if you place the two sub boxes side by side, they will acoustically couple and the frequency response will go down!!!

[@scottwolf8633]

Try dipole loading.

[@sonusancti]

2x2x2= 8 cu ft. correction

[@Toid]

Correct. But we are not interested in the external volume. We are interested in the internal volume. The internal volume of the double front baffle bracing and subwoofer is about 6 ft.³.

[@jessicaembers924]

My answer to if your 21" sub ain't got enough OutPut in a sealed enclosure is, get yourself TWO 21" Subs in Two sealed enclosures. And if you're into BandPass make it Four 21" subs! :-)