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

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.

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.

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

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

That thing is a beast!

You’re an excellent woodworker !

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

Great job 👏🏾

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 😇

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 🍺

Very very nice.

it's beautiful

This really makes me want to build a sub!

Nice work!! Came out super clean!!

Great job.

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.

Xcellent work awesome 👀 😊😊

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

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.

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

You killed it!

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!

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

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

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

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

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

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

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 😂

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

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.

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?

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

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. 👍👍

any design or sound test results? nice job !

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

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?

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.

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

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

Looks awesome but you forgot the bottom of the sub

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

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.

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

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

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

Looks good, but why nails instead of screws?

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?

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

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

What amp for the sub do you use?

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

TOID and DIY Audio Guy brought me here. 🤜🏽

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.

What are the mwasurments of this enclosure?

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

What kind of amp are you using?

why such a small cabinet ?? good build though

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

What part of TX are you from

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

What size T nuts did you use?

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

Try building an 18 inch open baffle sub…

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

Throw some poly fill in and it will dig deeper

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

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

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... :-)

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

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

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.