Ultimate DIY Subwoofer. Let's Build The 18" Ultimax

In this video we will design & build a sealed subwoofer. We'll be using the 18" Ultimax subwoofer from, Dayton Audio.
UPDATE FOR SUBSCRBERS: Yes I'm still planning to build Parts-Express kits, but unfortunately they are sold out everywhere. As soon as they are available again, we will pick right back up! Thanks for watching!!

[@MeTuLHeD]

You didn't paint the bottom? My OCD is screaming right now!

[@DIYhyfy]

🤣🤣🤣🤣🤣

[@constantine2731]

​@@DIYhyfy😂😂😂i miss messing up my brother books and DVDs back in the day he was odd as f he used to come back from school and go crazy 🤣

[@nickross1987]

Was thinking the same thing 😂 good job tho otherwise

[@merwynvincent]

He didn’t paint the inner walls too!! Is ur OCD a hypocrite!!😅

[@MunKeeButt67]

A two tone grey/ white or marble wrap would look good. This is a brilliant job 🙃

[@MiG-40i]

nice and clean job dude🤙the only thing i would do different is to use black screws maybe😊. I always had ported subs... i wanted that low end power. right now i have my first sealed one and i never go back. much more presize, quicker, dryer... way more controlled and it still goes waaay down to almost 20hz. that is deep enough 😇

[@AshyLarryTM]

Great video! Best wood fill you can get is that Titebond you have and the saw dust from your enclosure 👊🏽

[@Marzen216]

I just received this kit from PE. After watching this i feel validated ❤❤. This should pair up well with my two 12in subs and i have one port left on my DSP-Mini.

[@briansimmons5363]

Nice, did the 12" box that rocks. Best sub ever.

[@briansimmons5363]

the copper box that rocks

[@askmatt7283]

You did a really good job with this. Would love to see some frequency sweeps and show off how it’s performing in your room. Keep up the good work 🍺

[@DIYhyfy]

Thank you! Should have a video with measurements of different things coming soon.

[@rakitakhan]

It's easy to round out the corners inside the box also. Use a small ball or balloon in each corner and use spray foam behind it to fill the corner. This made a HUGE difference in my subwoofer. You can also round out all internal 90's in a similar way essentially making a tube with the woofer at the end.

[@tomkocur]

huge difference in what? Because acoustically, I don't see how any kind of chamfering or filleting (outside of areas designed for an airflow, like ports) would make any difference in a subwoofer. A sub like this will not play anything above 80Hz, which equals ~2m halfwave. Halfwave this big doesn't care about your little fillet. You do it on the outside because it looks better and is safer when there are kids around, but acoustically you don't improve anything. Fullrange boxes are a different story, baffle diffraction is a thing.

[@rakitakhan]

@@tomkocur Regardless of what you think or don't see, it DOES make a difference. I'm not a sound engineer but there is an improvement for the better in the sound and what I can feel.

[@tomkocur]

@@rakitakhan alrighty then 🤣 whatever makes you happy.

[@rakitakhan]

@@tomkocur FO. You must be one of those that think they're always correct. IDC. YOu can be right if you want.

[@tomkocur]

@@rakitakhan I'm not. If someone presents rational arguments, or at least shows a measurement, I'm more than happy to learn something new. All you bring to discussion is "trust me bro" with no further explanation or any kind of proof.

[@shaymcquaid]

Thanks to you, I have another great Boz Scaggs song! /,,/,

[@gene8933]

I have 2 18" Ultimax Although mine are stuffed. I will have to measure 1 with and 1 with out.

[@airtow6766]

Great driver for a build and I might as well give personal advice like most commenters. More internal bracing would have been good and some internal damping material to break up reflections would be smart. Good vid!

[@dippitydoinit]

Another nice video. I have one 15inch Ultimax kit with the Dayton Audio SA1000 amp and it shakes everything in my smallish house. Personally, I would have used some corner bracing and stuffed the box with polyfil but maybe that's not necessary.

[@DIYhyfy]

Yes this thing way exceeded my expectations. Definitely could use some bracing & stuffing. Wasn't actually planning to use it daily, but I actually have been. Will definitely wind up doing so. Thanks for watching!

[@DIYAudioGuy]

That thing is a beast!

[@m4c1990]

Damn, that 18 woofer looks very sexy...

[@halcyon7005]

If you haven't stuffed that pretty much to the brim with polyfill you are in for a treat when you do. The quality of the bass will go way up as well as SPL without distortion. Also, are you using any EQ or dsp to boost that roll-off? Ultimaxes do very well down low with that.

[@yesterdays-tech]

Awesome dude! New to speaker building myself. Have been tackling the DIY perks build. Was awesome to see your simple tool high precision build.

[@DIYhyfy]

Thanks for watching!

[@audiofrik]

You really did an excellent job in the creation of this video. Thanks.

[@jimtaggert7268]

You’re an excellent woodworker !

[@AsadAbbasi00]

What are the mwasurments of this enclosure?

[@DIYhyfy]

I did not take any measurements for this. I may take some for a future video on subwoofer measurement.

[@artotunkkari9684]

Sealed enclosure is only and right choice for ultimax series subs.

[@o.walker1370]

Why?

[@artotunkkari9684]

By looking parameters

[@pudintain9656]

What was the amp? And what was the xover point?

[@DIYhyfy]

I use a Crown XLS 2002. Xover around 80hz or so, system depending

[@Alex-yv8ej]

Great project! Can you tell me the dimensions of the case please? How many hz does the subwoofer play with these dimensions? 33hz or even lower? How thick are the MDF boards?

[@DIYhyfy]

This sealed enclosure is right around 2ft³. A sealed subwoofer like this can play well into the low 20hz range. Given enough power, this will play just about anything you throw at it. Sealed drivers also benefit from "room gain" allowing them to get a boost from boundaries.

[@Alex-yv8ej]

@@DIYhyfy Why didn't you take the building proposal from part express with 120l (4 ft³)? How deep can you get with your case? It's about half of part express's construction proposal.

[@CHUDHUCKER]

@@Alex-yv8ej at 46 seconds he does the 4 sqft

[@JensHove]

Very very nice.

[@charlesflute5737]

Great job 👏🏾

[@garygranato9164]

why such a small cabinet ?? good build though

[@Myhomeentertainmentsystem]

Thought about building speakers, but I found a good deal on some Peaveys

[@fabientaylor3873]

I read that this UL18-22 is made for sealed enclosures

[@desasch1687]

I have two of these in my pretty large home cinema. Going down below 20hz DSP'd in a pretty flat curve. The only problem is that the box is WAY to light for the power of this thing.

[@DIYhyfy]

I recently did some extensive bracing on this one. Should have done it for the video, but I was rushing things. Thanks for watching!

[@johncrespo4904]

Why the hate for sealed enclosures? Ive run both sealed and ported, and I feel sealed produced a cleaner tighter bass.

[@DIYhyfy]

Sealed is such a solid option. Especially for beginners to woodworking. I highly recommend them. Smooth roll off as well.

[@Gator11178]

This really makes me want to build a sub!

[@DIYhyfy]

What are you waiting for? Go for it!

[@megatron6238]

WHAT IS THE DIFFERENCE BETWEEN YOUR ENCLOSURE MEASUREMENT AND PARTS EXPRESS ENCLOSURE AND WHICH ONE GOES DOWN TO 19HZ

[@DIYhyfy]

I believe the PE enclosure is roughly the same volume. I'm sure both will play to 19hz, but at what level in your room is tough to say. If you want subsonic bass, go with a bigger driver perhaps.

[@paulcsaszar5824]

Awesome job looks beautiful

[@imip.1252]

Greating looking sub, nice job there! I'd love to see the measurements of it - with room gain, it could even dig deep. Do you think that a sealed 21inch would be a lot better than this?

[@DIYhyfy]

A sealed 21 could definitely compete or outdo this, depending on driver parameters. I recently built a vented 21. Check out the build. Thanks for watching!

[@buckmclean8391]

Please tell me...would you recommend this for music only? I want something that thumps.

[@DIYhyfy]

Yes absolutely. I only use for 2 channel, and I couldn't he happier. I'm comparing this to dozens of other good subs when I say that.

[@buckmclean8391]

Do u think the dayton 500watt plate amp would be enough for one of these, 2 channel music?

[@DIYhyfy]

It's possible, but I wouldn't count on it. These are pretty power hungry

[@chefchutardo5215]

Nice job, i have the same sub in the same size sealed box. Hope you do the measurements in this ! My wife hates it, i love it 😂

[@DIYhyfy]

Its a beast!

[@boltingskyline5234]

Looks nice. I'm no woofer expert, but isn't it best to incorporate a passive radiator opposite the main driver when using a sealed unit? I say this as My Sunfire XTEQ12 is a sealed unit with a passive radiator opposite the 12" Driver. Nice video. Makes me want to attempt some kind of custom build. 👍👍

[@DIYhyfy]

Passive Radiators are used to tune an enclosure. When we build sealed enclosures, we can tune the enclosure by controlling the size. PRs are great for certain use cases. But not required for all.

[@iyona14granturismogt6gtspo7]

A matching sheet of tempered glass on top to make it end table coffee table.

[@justinmanny86]

Once partsexpress restocks their 18" kits, Im planning on getting 2. I currently have dual SVS PB13 Ultras and they sound great but Im always on the hunt for deeper and better bass. Do you think 2 dual sealed Ultimax subs would be deeper/more output than the dual PBs? Id love to hear your opinion

[@DIYhyfy]

In all honesty, I have not heard the PBs. With that said, I can't imagine anything commercially available under 5K that would come anywhere close to one of these in output. As popular as these were, you should be able to find max spl numbers pretty easily online. Do Not let the sealed myth fool you. I've had competition subs that didn't play this low and clear.

[@justinmanny86]

@@DIYhyfy Thats great news! Im not sure how I didn't hear about GSG enclosures so I ordered an 18" MartyCube enclosure. I couldnt be more excited to build this thing! I'm planning on building 2 of them. My living room is about to sound insane in a few months lol

[@herrtrigger7220]

Before you buy these and get let down, a single Stereo Integrity budget 18 is louder than a pair of these from 20-40hz, using less power also. Built simple sealed subs with (2) SI drivers each sharing common airspace, 14 cu ft each, single Crown 2502 in Y-mode powering each driver from the L and R speakon outputs. One amp per cabinet. Ultimax soaks up plenty of power but a pair of them each sealed with the Crown clipping (800W per channel) in 4.5 cubes cannot even beat a single Hsu VTF3. It's your money. I wish I had known before I spent days building the Ultimax enclosures, what a waste of time. Erin at Erin's Audio Corner uses the same budget SI 18s in his theater, for good reason. Had to lower the sub vol on processor quite a bit as they were overpowering the room like crazy where the Ulimax were just 'decent' with about 40% more juice.

[@DIYhyfy]

There are undoubtedly better subwoofer out there, at better price points. There are a lot of these in the used market, and 2nd hand through other means. I actually purchased this for about $50 used.

[@_Wake_Up_If_U_Can]

We also purchased (2) Stereo Integrity 18V3s ($200 each including shipping). Built one box so far: 8 cubic foot sealed. Added a wooden ring around the woofer for a waffle grill protector. The surround sticks up 3/4" an inch requiring something directly placed on the woofer for a grill to be used. Still need to paint the wooden circle. We will be building the second 8 cubic foot sealed box this weekend. We designed a wedge box that matches the angle of the back of our couch. Sounds good but definitely does not have the same low end output as our: - (1) Alpine Type R 12" in a 4.25cu foot vented box tuned to 21hz -(2) Infinity Reference 1262Ws each in their own 4.56cu foot vented boxes tuned to 21hz Winisd shows the Alpine and Infinity Reference flat output to 21hz like 12 db ahead of the SI sealed 8cu foot, but below 20hz that 18" SI has a LOT MORE OUTPUT. We are using a Denon AVR760 LFE out to a Rolls M18B interface changer to XLR/line driver to a Crown XLS2000. We have a Parts Express dsp device on it's way. We have some room peaks up high that are very obnoxious and rattle our teeth.

[@Wannakatana2112]

Why not router a single piece of wood with a recess? Wouldn't that be more solid?

[@DIYhyfy]

Potentially, but they are firmly laminated together, and attached to a large brace. I'm not sure how big of an impact the extra millimeters would have on rigidity. But never know

[@PATRICEBAUDER]

Bonjour de la France........... superbe travail, j'aime beaucoup.......... vous travaillez dans de bonnes conditions, aération et ventilation, avec des bons outils, de la place dans votre atelier et aussi la possibilité de travailler sur le parking devant la maison, c'est vraiment très très bien ----------- ce "subwoofer" est très bien réalisé, il doit être fantastique pour le home-cinéma et également pour la musique, mais je pense qu'il doit falloir beaucoup de puissance, au moins 500 watts RMS en classe D pour qu'il fonctionne bien. un grand bravo pour votre travail

[@TerenceGrier]

I have this sub, in a 6 cubic foot ported box, in a 2018 Toyota Rav4

[@DIYhyfy]

Dang!!

[@richarddillon2632]

I have built 4 of these and they are great. Looking forward to seeing more of your videos . What amplifiers are you using? And what kind of spl are you getting? I at 40hz am at 128db using a xls2002

[@DIYhyfy]

Hey, yes these sound great. And so much more clean sealed. I've got this one placed directly behind listening position, and it doesn't disappoint! I'm powering all of my subs using a Xls1500 I believe. I would have to check exact model number. It may actually be the bigger Crown. I'm planning to do some measurements of lots of things very soon.

[@clburdick1]

Have you taken any measurements on the sub's performance? Curious as I'm thinking about making 2 of these and I'd like to see what you are getting out if it

[@DIYhyfy]

Hey I havent measured, nor plan to very soon. Its quite heavy. Subjectively this thing gets way louder than I need it to. It also digs very deep. I use plenty of power from a Crown amp. With its small size, and ease of build, its a great option. Also, this was in a much larger enclosure, tuned very low. I MUCH prefer the sealed.

[@clburdick1]

Which Crown are you running? The XSI 2502 puts out 750-800 watts per channel, seems like one of them could push a pair of these without a problem.

[@stevenshelp1107]

I've really considered the parts express passive radiator version of this sub. Not really that affordable but looks very enticing for size and extension. Also should be better SQ with the higher quality woofer on that model.

[@Acoustic_Theory]

The Ultimax 18" is happiest in a sealed box. The sealed volume helps control the moving mass of the woofer.

[@AliTran-h3u]

Do you have to have a power amplifier? Or you just hook up to speaker output?

[@DIYhyfy]

You will need at least a dedicated channel of a power amp to drive a subwoofer. Most cases you would have a dedicated amplifier, just to power your subwoofer.

[@jameshuntley428]

Looks good, but why nails instead of screws?

[@DIYhyfy]

Screws are highly unnecessary. Wood glue is stronger than wood. Therefore I don't see the need to add screws to the equation. They make finishing much more difficult & time consuming. Thanks for watching!

[@gtrguyinaz]

Try building an 18 inch open baffle sub…

[@DIYhyfy]

I would definitely like to try OB subwoofers eventually!

[@devswarring383]

Xcellent work awesome 👀 😊😊

[@karliemorris7318]

it's beautiful

[@Wannakatana2112]

Where do you find an amp pushing that much power?? I can only find 100x2, 100x4, etc

[@DIYhyfy]

Crown xls series. Has many watts of headroom. Thr other channel is running a 21" with no sweat.

[@Wannakatana2112]

@@DIYhyfy thanks! I want to get into woodworking and speaker building

[@AlessandroMinoja]

I have the same sub! Why you don’t use some foam in the cabinet?

[@DIYhyfy]

Hey, I since have. Didn't have any on hand for the build. Thanks for watching!

[@randomgene7]

any design or sound test results? nice job !

[@DIYhyfy]

Hi, at the time I didn't have a reliable measurement setup. I will likely measure lots of things in a future video.

[@Julius1225]

I really like the way you have build it this woofer. For how much you can build a 15" ? No paint...just the box itself?

[@DIYhyfy]

Tough to say. Really depends on the current prices of materials.

[@joeltopete8910]

Need 2 for 18”s

[@keijojaanimets819]

What kind of amp are you using?

[@DIYhyfy]

Crown XLS 2002 drivecore

[@rayadhali6136]

so no demo? what a waste of time. good thin i skipped to the end to make sure first.

[@DIYhyfy]

Yes good thing you skipped! You didn't get to hear 20hz! What a waste!

[@rayadhali6136]

it has equipment to measure those things u dusha@@DIYhyfy

[@dezofhellborn]

Nice work!! Came out super clean!!

[@DIYhyfy]

Appreciate it!!

[@kellyutley510]

Just not enough,JTR has 36 mm and down to 10 HZ

[@DIYhyfy]

Not enough for who?

[@0BURNT0TOAST0]

Not enough ? The JTR is like 5x the cost too. I would think you could get all you need out of these. FWIW I'd hit a stereo integrity HS24 waaay before a JTR.

[@paulcsaszar5824]

Looks awesome but you forgot the bottom of the sub

[@DIYhyfy]

I finished the bottom & installed feet. As much as this beast weighs, I doubt many will ever see the bottom of it!

[@Blockyroads88-88]

Were did u buy the mdf so i can build one myself!

[@DIYhyfy]

Local lumber yard. Available at any home depot & Lowes. .75" mdf

[@Blockyroads88-88]

@@DIYhyfy oh okay thanks!

[@worldofradomness1890]

What part of TX are you from

[@DIYhyfy]

I'm in north central Texas

[@wilsentwins]

What amp for the sub do you use?

[@DIYhyfy]

Crown XLS 2002 drivecore

[@spezzy]

Throw some poly fill in and it will dig deeper

[@69camaro19]

What size T nuts did you use?

[@DIYhyfy]

I believe they were .25"

[@69camaro19]

Thanks, I ended up getting 1/4-20's.@@DIYhyfy

[@mattadams7922]

Ohhhh Glue and screw man. The screws will create a mechanical connection and help to seal it that much better.

[@DIYhyfy]

Yea, no thanks. Glue is plenty strong, and no need to fill 100 screw holes!

[@mattadams7922]

I'm terrified if you used 100 screws. I get it's a big box but for the joints yeah all day screws and glue the vibration from the sub can separate the bond after time as the brads can pull loose just like the glue bond can crack and break. I tend to use a slightly flexible adhesive for that reason. Your box, your build, I've just learned from experience that vibrations and pressure especially sealed can really do some stuff.

[@bobslave7063]

Great job.

[@DIYhyfy]

Thanks for watching!

[@phoenixtonstudio8765]

What can i say... Cabinet material is too thin = boom box. Cabinet material will resonate as hell... and the cabinet will have a high sound transmission, up in the lower mids... So now you have two problems... wobbly bass, smeared lower mids, cause you can not integrate the sub right, into the main system. The sub will be locatable and sounds lousy ! No screws in the cabinet = the cabinet will crack sooner or later, especially under higher SPL... Why ? Cause the pressure which can not escape like in a vented box... A closed box must be built stronger than a vented one, cause of the pressure inside ! I build my own subs, for many years now and built speakers for over 40 years now... And say, this built was wasting time and money. My last built with a 12 inch sub, in a closed box, had a cabinet thickness of 50mm ( a special design of me = no sound transmission through the material ) ! Many... many screws to hold against the pressure inside. And the overall weight of this 50 ltr net 12 inch sub is 64 kg, without a single brace inside, cause the cabinet is rigid as hell... The complete sub system ( multiple 12 inch ones ) go down to 20 Hz, with under 1 % THD in the room, and a Group Delay of only 7 ms... and has a overall weight of 214 kg ! This 18 inch sub here, is a big air pump... nothing more. Cause of the weak built. I have 18 inch subs in my listening room ( the 12 inch are in my mastering studio ). One of the 18 inch sub has a weight of 150 kg ! The first built with a 70 kg built was weak as the built in the video ! Boomy, smeared lower mids and locatable... and this, with 44mm cabinet material ! After this failure, i designed the new subs, with the massive, i mean massive cabinet... Now the 18 inch ones ( i have two of them ), go down to 20 Hz smoothly, are good integrated into the big 4 way system and do what they should to do... Bring out clean the first two octaves of the frequency spectrum... So my advices are... Build the sub again... with a way more rigid cabinet, with many screws, and many braces inside... and damp it with stuff, which is used in cars to damp the car body... Then you have a chance to get clean bass... when the sub is well integrated into the main system... cause the main system must be delayed to bring out the best and to get a better Step Response... And build two of them, than you have a better choice against room modes... and the bass will be more clean, cause you have more power... means less cone movement = less THD = more dynamic reserves... :-)

[@DIYhyfy]

Thanks for watching!

[@wadimek116]

If you don't use a brace then you are a moron instead lmao. Many people did measurements braces do wonders and you don't need super thick enclosures with them. You could also do isobaric configuration if you really care and then walls can be quite thin and not much braces required. You also don't need to dampen sub as it changes the Q so you may lose a bit of efficiency for not much gain as you usually play below 80hz. I tested it in my enclosure and harmonics are very very low, my couch is resonating more from the bass waves than any harmonic distortion from enclosure is happening. Before you do such claims you should prove it first with measurements

[@sudd3660]

great content :) i have mostly built sealed myself, definitely needs dsp to get the most out of them. when you have a unit like the minidsp shd studio any passive subwoofer becomes fully adjustable with peq, just adds dac and power amp :) i find sealed goes deeper and have about the same performance pr volume, ported wins in output pr dollar if you do not need the lowest frequencies below port tuning. i got respectable 107db at 12 hz from my two 10" shallow driver subwoofers.

[@DIYhyfy]

Right on! I may play with DSP in future videos

[@gemargordon6885]

Are you using the miniDSP shd studio? I’m building a 4 12” sealed and I need something with eq! I bought a dayton dsp but I’m reading reviews that most don’t like to iWoofer app 😅

[@sudd3660]

@@gemargordon6885 i use the shd studio as volume control, room correction to main speakers and making passive subwoofer active, with all the dsp power of the mindsp. it is a pure digital unit so you need dacs and power amps. alternatively plate amps, hypex got digital inputs. minidsp has more units to choose from now, so pick the one that fits.

[@deaconbruce7216]

I have 4 of these sealed in my S10 blazer on a 8k amplifier and it drops low!

[@cordel666giglesworth6]

I've never been a fan of sealed enclosres but I have to say your is excellent

[@Toid]

You killed it!

[@brianraulerson5037]

Toid would've used 25 more braces.

[@Vegas_Baba808]

TOID and DIY Audio Guy brought me here. 🤜🏽

[@DIYhyfy]

Thanks for coming!!

[@GGray-gg4yn]

Nice clean job ! Would like to see a volume and frequency pot.

[@DIYhyfy]

Thanks, definitely planning a video dedicated to measuring everything I've got.

[@christopherparis6841]

4.5 cuft??? Holy fk dude get u a hundred dollar tops lanzar maxxp sub jffc a 15 calls for 2.15 sealed all the way to 24hz resonate freq.

[@DIYhyfy]

I had this on hand from a friend of mine. While I love it, I wouldn't have purchased a driver this pricey normally. Thanks for watching!

[@mohammadwasilliterate8037]

*One 18" subwoofer surely is plenty for most people, that thing would really sound great am thinking.*