Dive Into Deep BASS: Build Dual 21 Inch Subwoofers Yourself! - Earthquake 21's

#subwoofer #bass #bassboosted
Ever wonder if a 21" sealed subwoofer can create bass you can feel? Check out this build as I take an SB Audience Rosso 21SW800, where I test whether or not room gain can help me reach subsonic frequencies in my room. Tested and revealed both room gain and bass that you can feel.
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[@wally7856]

1st KZbin build I seen where the builder understands proper bracing. Nicely done.

[@silicon.alchemist]

Quick hint: Tee nuts which have the teeth on them are very difficult to install unless you can hammer them in. This is even more difficult on the inside of an enclosure. They also don't work that well on MDF. There is a variation called a Propell nut, which does not have teeth on the flange, but has small ridges on the barrel. These are much easier to suck in with a bolt and work much better when you don't have hammer access. If you are worried about spinning them in the hole, just apply a dab of epoxy when you install them. Available at most woodworking stores and Mcmaster Carr.

[@wadimek116]

Thank you unfortunately I learned it hard way

[@mullinperformanceaudio5902]

We got to see the moment Nick realized he was a basshead.

[@Toid]

Haha! I mean I do like this, but I also feel like there can be too much bass 😂

[@blakebrockhaus347]

@@Toid no such thing

[@Toid]

@@blakebrockhaus347 😂🤣😂🤣

[@mullinperformanceaudio5902]

We really need to get you and Justin to Slamology next year.

[@toddspraker8916]

There can never be too much bass.

[@cragre28]

I learned a trick for t-nuts or hurricane nuts when I built a bandpass box a few years back. After you have you speaker cut out done and before you assemble the box, put the subs into the cut out and drill out the holes the same you did. Then install the t-nuts just like you did, but go ahead an drill a small hole in the t-nut flange so you can run a small screw through the t-nut and into the wood. It will not fail if you do this and you don't have to worry about it stripping out, no matter how many times you take your subs in and out.

[@Toid]

That’s a great tip! I know some people also put a little bit of superglue when they seat it so that it doesn’t fail.

[@caidelander2561]

I’m so shocked this channel doesn’t have millions of subscribers. Awesome video and the subs look great.

[@frankpanis2748]

Great video! I'm already running dual B&C 21SW152 in LLT but I'm wondering to utilize these large boxes for a second 21" B&C and make them sealed. I also agree on feeling such a pair of 21" woofers. They indeed deliver the visceral impact that dwarf most smaller subwoofer out there.

[@jukkamaljanen6644]

I love these build videos! Tip: you can simulate box, analog/dsp filters and their effects on group delay with VituixCAD. It seems ported is pretty close to closed box after you have EQed it to equal FR curve. But there are other clear benefits for closed when you go below port tuning frequency 👍

[@russellanderson746]

Great video! I remember reading in Martin Collom's book that, in room, an f3 of around 40 hz. was good to shoot for due to typical room gain. Also, I must point out distortion increases directly with excursion...no matter what the distortion rating of a particular driver is.

[@MrAndromeda290]

Thanks for all your videos. I'm a newbie in the speaker build, but your videos give me a lot. Greetings from Slovakia.

[@MrCrabra]

What is your room dimensions? Room gain is dependent on longest dimension of the room. Great build by the way. SB Audience is available down here in Australia at reasonable prices. Cheaper than Dayton…

[@saber0089]

Nice build. I'm planning to build a 21" devastator to get that mid bass kick my 15's don't give. A lot of the tips you gave will be helpful to my build!

[@nuen7825]

I had the same issue and just bought a cheap 12' subwoofer and made a 1ft³ enclosure with port at 65hz for it. Now I feel the kicks from 65hz to 110hz flat. This little sub makes so much difference. Now even the old disco songs with lots of midbass sounds good in my sound system. Yesterday I seated in between the two subs and was amazing to feel the bass starting from the little sub in the left going to the big one to the right. It's so satisfying to see and hear this project finished!

[@zarboaudioprojects1430]

That is seriously impressive low, LOW frequency output! What did your father say about it if he heard it? Man that's like having 1/3 of a standard door as a subwoofer. I had a multi-12" Titanic sub in an attic of very similar shape and the room was REALLY good at boosting the low end. I can only imagine what two 21" subs feels like! What happens in the other rooms of the house when you're running bass sweeps? Anything fall off the shelf yet?

[@shawnbrennan7075]

Beasting that subwoofer around gives me Gene DellaSala vibes. Nice work! Bottomless bass, gotta have it.

[@DimitarAtanasov-o3m]

I use 4x12" sealed DIY and can confirm that sealed + DSP (or infinite baffle if possible) is awesome. There is no replacement for displacement! My next will be at least 2x21-24". Great content here!

[@Toid]

That is awesome! I ended up doing two 21s with Dsp and am very happy with it. It’s pretty amazing when you can start getting those big subwoofers to move air. I had a friend come over the other day who thinks me for turning on the bass shakers. I told him I didn’t have any bass shakers. And he was surprised. He said I got all that shaking from your subwoofers? It was pretty epic.

[@DimitarAtanasov-o3m]

@@Toid it needs to be heard to be believed! After someone hears the transient response and the way this pressurize the room, no other acoustic type of enclosure could beat it :)

[@arnicus208]

When soldering connectors, attach the two mating portions together; so if it does get soft from the heat, the opposite side of the connector keeps everything aligned until it cools back down.

[@jeromelester8]

Super solid enclosure - nice job!

[@DarienCharlton]

Man...I was going to build a couple of copy cat SVS PB16s (with an 18" driver) but this video makes me feel like I should build 2 sealed 21s instead...

[@Acoustic_Theory]

Bag End used small sealed boxes with EQ since the 1980s, but in many cases the room is the right size to provide enough gain at low frequencies that very little EQ is needed. This is an interesting build video in concept. You could gain similar performance by using more smaller subwoofers in similar small sealed boxes, like doubling up on the 15" woofers instead of going to a 21", but the 21" is a way to skip right to the larger Sd instead of buying multiple small subs.

[@bradstone2603]

I'd be interested in a video where a previously made set of speakers is remade but with a more comprehensive wall material (say, laminated MDF/Synthetic Stone/Accoustic Pinboard, or some other such idea) and show a side by side comparison of the specs of the two.

[@FakthorX]

Excellent. You make me want to build a wall of these

[@N4CR]

Great to see this. This isn't even a high excursion 21" (I'd have gone for a different driver personally). 21" is in my opinion the minimum you need to get good infrasonic and low group delay and avoid a million 18" subs. Far higher efficiency too. DIY subs are the only way to go if you want heaps of bass. You can't buy big 21"s or more usually. But don't stick them all in tiny boxes. High excursion 21s need 1m3 or more to really do well sealed typically and you want to ensure they have a long enclosure. I'm making mine from Epoxy instead

[@joaquinkline3191]

Not to knock his experience but my only minor quibble was, if you have the room (he did) why squeeze that bad ass 21” in there? I realize it’s extra weight and probably requires some help to move around, but people buy couches all the time. Once installed though, you don’t need more people to get it just right if that’s required later.

[@benfits8768]

I'm about to build some. I was going to make them 600x600 like this video but you are saying the bigger the box the better? If I make it bigger what would you suggest?

[@RobertCookcx]

This is a fun experiment and I understand what you mean by feeling the energy. The car audio guys get the benefit of "room gain" far easier with nominal 12" subs even. As much as I am tempted to try this, having monuments in my media room would be cumbersome vs. just rolling with my 12" sub and the 4 butt kickers in my seating area. If I was pumping 30 Hz to the living room, it wouldn't take long for my wife to be knocking on the door. LOL I will want to try it though....

[@cabasse_music]

thats it i'm building one of these for my office. 9' x 8' x 9' so totally not overkill at all

[@nintariplays5654]

so odd, I thought you would have felt 20Hz and below pretty good with the ported ultimax build you did in that room :D I built a ported one using the 18" ultimax and OMG...even in a 24'x24' unfinished basement with block walls and concrete floor... it fills this room very very well!!

[@Toid]

You could feel most of it. But it’s a different feeling. And there’s definitely some bass that you could hear before but now all the air in the room is energized making it a unique feeling.

[@jismo7]

I built a ported sub for the Dayton Ultimax 18" (about 8 cuft) and it did indeed get to 15Hz. However, in a 17ft square room it was impossible to DSP it to a reasonably flat repsonse. It was totally unmusical and boomed. I ended up selling it.

[@brianraulerson5037]

You got 2 subs and your boys got a new fort from the boxes. I certainly have sub envy now. Those things are crazy!

[@tdevosodense]

Can you build a earthquake horn , used by cerwin vega in cinemas in "the old days" 👍👍👍

[@Toid]

I really like that idea. That would actually be really cool.

[@georgegermain740]

Would a Leslie style rotating horn make a good sub? Or is that better left to mids and higher htz?

[@johnnycorn7225]

I'm getting ready to do that setup with three stereo integrity SQL 12s 3 cubic feet sealed for the first compartment firing into another 10 cubes in the enclosure, always graduating angles and doubling the volume of the throat through three folds. That particular horn setup sounds like nothing else and is worth the work

[@edierllamasfixedthis]

THIS is the page I’ve been longing for.

[@danpetermann6509]

I've been feeling the bass since 1992! I have a pair of Cerwin-Vega AT-100's (15" woofers) pushed by a DBX BX mark II amp. I'm finally redoing the surrounds as they've really gotten stiff over the years. I can't believe how unbelievably reliable they've been

[@iikatinggangsengii2471]

im enjoying this sp2000 - c9 -a12t sound, sound great but still 'down to earth' and portable sound experience, which is good thing and suit the devices/synergy

[@markfischer3626]

This is an excellent design. The principle on which all woofer/enclosure systems can be analyzed is Newtons second law of motion applied to forced oscillation, the same way your cars suspension is designed.. The FR is controlled by 3 parameters, the mass of the moving part, the cone, voice coil, bobbin, the spring constant, and the damping factor. In this design, a quasi acoustic suspension design the stuffing plays an important role. The woofer is forced to push air back and forth between the fibers causing a frictional loss generating a tiny amount of heat related to velocity of the air. This is the same principle that causes the space shuttle to heat up when it reenters the earth's atmosphere at high speed. The spring constant is to a large extent controlled by the difference in air pressure inside and outside the enclosure. This eliminates all of the problems caused by ported designs. Because the air pressure is applied uniformly on the cone there are no differences in radial or circumferential force on different areas of the cone eliminating the twisting and shearing forces mostly mechanical suspensions create. At critical damping the response falls off at 12 dB per octave below system resonance which means you can extend FR below resonance with equalization. The Crown amplifier was also an excellent choice. Gobs of power, extended LF FR, excellent reliability and customer support and a great value. Its what I would have chosen.

[@romanalison8972]

Worth having a look at Scott Manley's explanation of re-entry physics on the Tube (search Heat shields...).

[@fieldcar]

Just a FYI for people looking for ballpark CEA-2010-A measurements, the B&C 21DS115-4 puts out the following in a vented configuration with the vent blocked. Though, there are a lot of differences in the ts parameters, so take this with a grain of salt. 10Hz: 97.2 12.5Hz: 108.5 15Hz: 114.7 20Hz: 113.5 25Hz: 115 31.5Hz: 119.3 40Hz: 125.3 50Hz: 128 63Hz: 129.6 80Hz 131.5 100Hz: 132.9 125Hz: 134

[@TokeBoisen]

I assume these are in-room. 110 at 20 Hz anechoic is insane sealed.

[@fieldcar]

@@TokeBoisen No, CEA-2010-A requires ground plane measurements outdoors without any nearby buildings/objects. Look at audioholics' subwoofer reviews for photos when they take measurements. The one large flaw with these measurements is the variable of weather/temperature that skews results.

[@TokeBoisen]

@@fieldcar, yeah, I realised after, my mistake. I figured it must have been in-room due to the figures. The value of surface area I suppose.

[@fieldcar]

@@TokeBoisen I know what you mean about the surface area. I just got the monolith THX 13, and it doesn't even come close below 15Hz. I guess I should have just mustered up the courage to DIY.

[@TokeBoisen]

​@@fieldcar Well, there are tradeoffs. To get those SPL figures from a sealed sub you need tons of power, and you'll need more DSP-shaping to achieve a flat response. The THX 13 is an incredible subwoofer for anything above infrasonic, and we don't like to admit it, but infrasonic content is not as prevalent as we can be led to believe. For what it's worth, I've considered redoing my enclosures as ported to gain the output above 20 Hz, as well as the efficiency gains.

[@bkims]

I think from my limited experience the biggest drawback of a low tuning port (aside from excessive VB) is that its length greatly increases group delay. Sometimes sounding like muddy/boomy bass (I could be speaking somewhat inaccurately here though). That said I think that short ports for midbass applications are unbeatable.

[@behappybevegan]

Fantastic build and result. Well done. Placed a link on the asr forum.

[@krevilplays]

I am attempting a similar sealed project with Bianco 18" 450W. This driver seems special. It has better low end extension. Initial sims show playing flat till 10Hz with max power and within 11mm xmax limits. 4.2cuft.(Qtc 0.88) looks to be perfect size without any power limit down to 10hz. Price is sweet too.

[@jasontimothywells9895]

Great video , I have 2 of these 21 inch SBs , I haven't had the time to build cabinets, and niw I am motivated again .

[@kevinfreestone9822]

Love this box. I usually use 3 quarter inch marine Plywood with a double baffter (so 1.5.inch), but will try this next time.

[@AwesomeSauceShow]

That's the video I was waiting for, for month's!

[@NTSCuser]

Reminds me of an article in a 1969 edition of Hi-Fi News in which the author built his own then, unheard-of eighteen-inch subwoofer enclosure which doubled as a TV stand and was styled to match his Quad ELS speakers which are not known for their low bass output.

[@audfrknaveen2256]

❤️❤️❤️❤️❤️❤️😀😀😀 no words !!!! I can see your excitement itself explains how incredible your build is 😀😀👍👍 what's the room size by the way? ..

[@soniclab-cnc]

yep...second box is usually easier to put together. I have most of my tolerances down for my machines but I have to tweak stuff constantly. I do some complicated builds and have lots of experience but still make mistakes.

[@BlenderRookie]

Your room is shaped almost exactly like mine. Old attic turned into a computer room , in my case. I have been contemplating going with a couple of 18 inch Dayton ultimax subs.

[@Amansshed]

I HAVE BOTH AND FOR MUSIC GO WITH THE ROSSO UM18 IS A MOVIE SUB FOR MY LIKING, BUT EVERYONE IS DIFFERENT

[@BlenderRookie]

@@Amansshed I don't listen to much music and they would primarily be used for movies.

[@Amansshed]

@@BlenderRookie the um18 is a monster sub for movies because it has such a heavy cone and xmax but if you got 4 rosso that wound better because you have way more surface..more surface is cleaner as xmax creates distortion.. you will need to be at least 20feet away to get the best out of them. put a 15 about 10feet away to fill in the dips from 30hz up.. you will get dips as your far away.. you will have to move the 15 to suit you.. its a puzzle

[@robertearlreynolds7064]

Large Driver, Small Volume sealed subs are my Jam. They sound great, but require HUGE power as they are crazy inefficient. But with modern D Class Amps becoming affordable, they are totally the way to go.

[@ladjkaoz]

you definitely got a thum up. I see other videos where the buld boxes but not a single graph of frequency respond... 👏👏👏 great job... I was watching this other Vid where he shows how to gain even more dbs by frequency cancelation. not sure if it would apply since you have your sub side by side...his name is Michael curties. probably you know all that...

[@scottouimet2865]

Yea ppl don't understand, I got 2 Resilient sounds Team 18s on about 20,000w and it's incredible

[@craigenputtock]

You're talented. I wish I could do that stuff.

[@Toid]

You can do it!

[@95Sn95]

Nice subs for a pro audio style, personally I'd think a high excursion sub would be more impressive, and H.E. doesn't mean bad SQ either there's several 21 & 24 high excursion high BL subs that are tight and accurate. The sundown 24" is an impressive speaker but I don't know the acoustics of it wether it's tight or sloppy. A future project that would be cool is build an experimental concrete enclosure vs a wood and do audio tests. Apparently there's crazy priced high end concrete enclosures but there was a guy selling them very affordable because well there just concrete.... It should be a perfect enclosure audio wise there's obviously a bunch of caveats of it tho. But a basic form a bucket some gravel chicken wire and a few bags of cement and PVC pipe an afternoon and whalah concrete enclosure... Sand and epoxy and it could even actually look nice... Don't get me wrong this is a nice project that will shake your foundation I'm sure.

[@GoalieNurse]

This is the type of bass I like- body shaking!

[@rigorhead01]

So awesome! I love building speakers!

[@jdrissel]

I like to use a couple of #4 screws to hold the T-nuts in on the backside. The washer trick is fine for initial assembly, I use it too, but after some play time and needing to open things up to make repairs or changes, those t-nuts might not be so solid anymore, and it is almost always the last $$+-=€°| one that falls off. If you are lucky it just falls into the box. If you are not, it falls through the spider and leaves you with a driver to rebuild...

[@AshyLarryTM]

Nick, you have the coolest shop. I wish I had the room for a CNC.

[@Toid]

Thank you. Now I just need to get the shop clean. 😂

[@Techdiscussed]

Did you build your own CNC?

[@Toid]

@@Techdiscussed no. It’s a CNC4Newbie

[@Bassotronics]

Some people go through hoops and lots of effort into making a box that is strong with lots of bracing so the walls don’t flex but in the end, all that work can be saved just by putting the subwoofer in a tube. Tube’s natural round shape cannot flex thus not needing all that unnecessary bracing and extra weight. Just put a thick front and rear baffle and you’re good to go!

[@Bassotronics]

On a side note, locating an 18” or 21” tube is a little hard. Although there are huge pvc water tubes that can be used.

[@vishaalgargi]

Bro u the og?

[@Bassotronics]

@@vishaalgargi Yes

[@vishaalgargi]

@@Bassotronics cool, brother i hope one day, i will have a system capable enough to play the bass i love u track so that i can finally experience it for myself.

[@ciddax754]

Unported 21" ... simply WOW!

[@FOH3663]

Very nice! fwiw; Un-check the auto ranging/formating... Re-size your OmniMic window, for standardization, ie., when measuring LF, subs use 200hz as an upper limit, 45dB-105dB Uncheck the auto formating... This way you quickly develop visual references for vis-à-vis comparisons. As always, keep up the good work.

[@GehirnfaschingDD]

Interesting project. At the Moment i consider building an active Driven subwoofer enclosure With a Sandwich baffle filled with Quartz Sand. Since youve got a cnc this would also be an interesting project for you. Also its Not quit common these days but it heared some speakers in 2002 and always wanted To build one… actually two of These.

[@kaitsobato]

These are some nice subs man ;D I have two 15" Ultimax in a 23"x20"x16" box but wish i would have made them more square-ish :D Have fun

[@danaolson2871]

Both sealed and vented woofer will have room gain. To match the output of a vented system you just need twice the displacement. So a second woofer of the same size or a larger woofer with the same Xmax and twice the cone area will do the job. The same size woofer with twice the Xmax would also work and you would have a very small box. It's all about displacement = Xmax * Cone Area. Just like in engines, there's no replacement for displacement. Sealed systems are high fidelity and have response all the way to zero Hz. Vented systems go whiff below the port tuning and they make low bass by ringing like a bell. That's low fidelity.

[@bassman9544]

yeah hehe

[@kellyswoodyard]

I have an old Cerwin Vega active 15" sub. It moves a LOT of air. I picked it up at a Salvation Army store, for $80. Had it serviced by my long term tech, he offered me $500, there and then. No deal.

[@3yearsago287]

You gotta see Steve Meade subwoofer he build for his home theater. It's huge!!

[@95Sn95]

Something hardly anyone does is it is a good idea to put some glue on the T nut, they are notorious for not staying seated and then everything spins causing a real bad time, then it's try n unscrew with sub facing down to keep tension on the nut. Just a blob of e6000 ontop or under it whatever.

[@itsmetorque]

Excellent quality uploads.. Even in 240p 👌🏻

[@StickySli]

Simce I discovered SB audience, I cannot wait to build some JBL old-school style bookshelf speakers with some 15" subs.

[@mrlinde6518]

Great video! Did you ever manage to perform some distortion tests on the 21" sealed subs? Also can you offer a quick word on choosing the ROSSO-21SW800 over the NERO-21SW1100D?

[@Manic1578]

Nice I run a single mach 5 FTW 21 inch sub in the same size box off a Inuke 6000.

[@glenlieder6673]

Pro tip: install t nuts before paint, use c clamp vise grips to install them.

[@QAT4969]

"that's enough talk, let's get cutting.." why does it seems familiar..like i've heard it sumwhere..? "enough talking, let's start eating" GUGA FOODS..!! haha..love your builds man..!! sincerely inspired by your work...will be joining you soon enough. gotta get that CNC machine & table saw 1st.

[@mephInc]

My Monoliths already take up a ton of room...... Hind sight I guess. Looks very impressive

[@MartinHAndersen]

Congratulations, fantastic results. My I ask why you didn't choose the SB Audience NERO-21SW1100D? Is the subs also for music, not just movies?

[@Toid]

This is going in my theater room, so it’s mainly going to be used for movies, but it sounds good for music as well. As far as why I didn’t use the Nero, it’s sealed output was not as good as the sealed output on this. This one just worked better for this design.

[@jimthvac100]

Besides these wonderful Sealed Subs you built I have not seen you build any of the acoustic suspension design, mostly build ported speakers. I understand One has to build a ported design when they want to use high efficient drivers (If they want it to go much below 50Hz 3db down.) I was curious if you considered building a sealed speaker (front left and right application) using the 15" Dayton Audio DCS385-4 or similar? This Particular driver works well in a sealed enclosure I model it using WinISD at 33.5Hz 3db down in a 3.9 ft3 box its about a 90db efficient. I was going to pair it with an 8" Eminence Beta-8A for lower midrange and the Selenium D250-X for upper midrange using the H6512 6.5” x 12” Wave Guide. and for upper frequencies using the DS18 PRO-DKN25 1" Phenolic Horn Loaded Bullet Tweeter (This tweeter is supposed to have very good dispersion and sounds great I bought a couple and playing around with them and they sound awesome. Crossover points of 200Hz, 1.2kHz, and 4.5kHz. Only reason I am thinking on this 4 way is for maximum dispersion. Even if you decided on a three way design I would enjoy watching you build it or even another sealed speaker design. I know the 12" Aurum Cantus AC300/75C2C can go down to 48Hz 3db down in a more modest 2.1 ft3 box.

[@e-zeescrossovers6188]

What's your thought about increasing cabinet dimension? For example, what would be the effect of keeping same foot print (depth + width) but adding some extra height to cabinet? Would there be a benefit or tradeoff to that extra internal volume, in this specific 21" sub application? For example, what if 1 or 1/2 cf was added as height?

[@altosack]

As he discussed, more volume will give a lower Qts, lower F3, and diminished power handling. He didn’t like the trade offs since with the combination of room gain and DSP it was flat to 10 Hz, anyway. I look at the power handling a little differently. The lower enclosure F3 will allow less DSP adjustment, and require less power to reach the same equalized SPL, so the slightly diminished power handling still gives at least as much overall flat SPL. Whether the increased materials and more required space is worth it is up to you. Myself, I would have used an 18” Ultimax in the same size cabinet. This gives you a starting Qts of 0.8 and F3 of 26 Hz, so almost no equalization is necessary. Of course, the 21” will move more air and has a higher SPL, but with a slightly less natural sound with the increased DSP adjustment. Horses for courses.

[@janus1977]

Awesome build, me wanty..

[@JakeAlmighty]

enjoyed the video. how would you say this box compares against the really large ported GSG diy builds? (ie. 20hz devastators) my room is about 24' x 16'

[@Toid]

There’s nothing really wrong with either box design. One of them is going to be ported, which will limit your frequencies below the port tuning and for best power handling, you want to make sure to have a high pass on it. With something like the sealed the advantages are you don’t need a high pass and you’ll be able to get those subsonic frequencies. The disadvantage with the sealed is, it’s going to take more power to achieve the same SPL at lower frequencies, which mean the ported will have more overhead. Now the question that I was trying to answer was, do you have so much overhead that it’s unnecessary. Ie, you’ll never use the overhead.

[@AwesomeSauceShow]

I bet you can get more content out of those subs, I would love to see reactions of people, maybe set a cup of water near them to visualize the POWER! ;)

[@furnoproductions1314]

what are your thoughts on the crown xls 2002 vs xti 2002?

[@alexbarkovsky4591]

Great job!

[@dennisbohner6876]

Always glue your sound absorption materials.... there could be some loosening if there are vibrations.

[@timLoder]

Have you ever considered making a set of speakers with violin holes beside the woofers?

[@danrussell9357]

Great Video

[@justinclacherty9181]

This looks great! When you model it in WinISD do you take into account the loss of volume from the bracing and the insulation or is it safe to ignore this?

[@Toid]

You do. However, with this being a sealed subwoofer, you have a lot more liberties with the internal volume.

[@justins.1283]

Wonder what those drivers would do in a folded horn cabinet?

[@philiptalbert458]

Awesome 👍

[@annihilationindustries1990]

🤣😀 Love your reaction to the first time you have heard 21s . wait till u hear them in a car walled off

I want to purchase the build design. But got some questions: - Is the woofer cut out part of the design? - Are the Speakon connection cutout parts of the design? - For the looking of the box, shouldn't it be better that the rear panel falls into the side panels? This obviously impacts the design of the bracing, but would be better looking. - What diameter to you use for the MDF plates? 25mm or 30mm? (30mm is more stiff) - Why dont you use a 38mm MDF for the front so you wont have to glue 2 front plates together? - You said the box is 6ft3 internally (170L) is this the real available space? - The braces are taking up space, what amount do they use? Will that impact the 6ft3 mentioned before? - Why dont you use a linkwitz transform and only DSP for correction? - You are using insulation/rockwoll to prevent resonance....but what frequency resonance are you talking about? - What is the impact of the insulation/rockwoll on the available amount of space/air in the cube, does it impact the 6ft3 available space? I hope you can clear this up for me and other people. Thanks for you reply!

[@reinenorrbin5120]

Great vid. So many comments, so little time.... How would you rate these small sealed boxes to a UM18 or the HTS544t, since you tried them all. Lets say its for ht 50/50 movies amd musk

[@thepirateswirled]

I would be interested too, since I'm inbetween 3 or more choices, the Dayton UM18 as closed box and more.

[@aktionp20]

Now I got to know. How do these sound with music?

[@Vietturtle2023]

Love it!

[@HPMIKE55]

Great job 😎👍 I just wanted to know where did you get the installation or can you send us a link where we can get the same installation you just installed ? Thank you 😎👍

[@Toid]

Do you mean the enclosure?

[@HPMIKE55]

@@Toid No sorry the rock wool

[@Toid]

@@HPMIKE55 oh, gotcha. They sell it all over. I think I bought this from Lowe’s.

[@johnstarks5323]

8:42 I would love to hear that on an ADMARK AD42 or CVR-D 3302

[@Miketheconservative]

Have you tested Rockville amps? Would be interested to see how they compare to crown!!!

[@versus023]

thats funny cause, since like 4 weeks I'm thinking of building a table into a subwoofer. I have to deal with a relatively small living room but open space with kitchen and hall way. I was thinking to build a 15 in the table, which have a 5.67 internal volume with port and braces. then I was suggested to go 18, and someone mentionned 21 and I was sceptic. didnt thinking those 21'' could go as low in a sealed enclosure. We have rougly the same volume available. Might do this one but not in the same form factor box.

[@N4CR]

Nice cab bracing btw..

[@jessicaembers924]

You should make that from pressed strips of solid iron wood!

[@bernhardh6184]

Great video! What‘s your verdict about one of these 21“ vs the two of them?

[@unknownspectre]

You mentioned building these with the PSS555's in the last livestream. At the price, this is extremely intriguing, particularly for near field bass. Have you modeled the drivers in this enclosure?

[@Toid]

I haven’t. I think Justin brought that up and then I had mentioned that it would be interesting to model in this type of enclosure. Part of the issue was some of the PA drivers that I did look at was the room gain started too late for my room. At least later than I would’ve liked. So you’d want to figure out what your room gain should theoretically be, and then model it with that.

[@crztrn1]

simply, awesome

[@Edinsism]

After having 2 subwoofers i don't think its possible to go back, even if those could easily output for that room with 1.

[@JungYT]

I would like to know more about the room gain and design that you were testing out.

[@Toid]

Thank you for commenting. I did a video on that. Here it is: kzbin.info/www/bejne/mZzVpaOqh6qqptEsi=RS5RQM3G2JJ7Pp4A

[@blaze2051]

the problem is your xti2002 Frequency Response (at 1W, 20 Hz - 20 kHz)so how exactly did you manage to get 5hz?

[@bournelucid]

I only have a single 18" and i can feel the lows in my chest, i cant imagine dual 21"s lmao🤣

[@st170ish]

Give Toid a bottle of glue and brush he turns into Picasso! Im wondering what its bigger brother Nero would be like, Qts is a fair bit lower a tad more Xmax heavier cone and 3db more sensitivity

[@Toid]

It didn’t model nearly as well as far as room gain was concerned. Honestly, I checked out quite a few 21 inch subwoofers in these are the ones that I thought would do best with room gain being considered. The other one’s really seem to be more tailored to a ported enclosure

[@Pentenfi]

Yes, finally! 😁

[@donjaun540]

OMG awesome. Kit please. 😜🙃🍿