Home Forums DIY Speakers and Subwoofers Sealed ~5 cuft UM18-22 Duo – Build Thread Reply To: RE: Sealed ~5 cuft UM18-22 Duo – Build Thread

  • splinter

    December 8, 2021 at 8:09 pm

    Remaining build pics.

    My 50mm Allen cap screws were only threaded to the half way point, so I had to slice down a stick of 12mm plywood with my bandsaw and glue them on the inside to pack out the mounting hole length. Worked well and there was plenty of excess thread I could use to make sure each bolt was properly threading into it’s tee nut.

    On the inside I pinched the tee nuts with a screw to mitigate risk of blow out, but install was painless in the end (better than when I did my Cinema 6’s, had to grind off one bolt head).

     I stuffed each sub with about 1.8 kg of polyester fluff, roughly 0.75lb per cuft, then stapled in some fabric strips to stop the fluff falling to the bottom, though that may happen over time regardless.

    Perfect fit. Here you can see my vibration damping feet, they’re about 30mm tall and made of really gummy rubber. Do exactly what the SVS ones do but these only cost me $30 for 8. Not much vibration in room thanks to those feet. They do make it super hard to move each sub around as the feet are so grippy.


    And here it is in the front of my messy soundstage! The speakers on the ground are my bass amp and PA foldback monitors. 

    I’ve been running the amp next to my desk while tweaking the miniDSP, once done I’ll hide all the cables away again. 2nd sub placed in the mirrored rear but it’s to disorganised back there for photos at the moment.

    I do regret not taking a photo of both subs completed next to each other haha, but each sub had final assembly next to it’s destined spot.

    Next post sound impressions and measurements.


    I will say there’s been a negative with these so far, and that’s the pressurization of my room. It’s so unbelievably easy with these to hit 100db during demos that while it hasn’t felt loud, my ears have gotten popped like you’ve been diving or descending altitude resulting with slight ache in both ears from the pressure. I’m very careful with my ears, have custom moulded musicians earplugs and the like – just had them running a bit hot for the room maybe. Also wonder if I should’ve gone with two PB-2000 pros hahahha, something ported to avoid that pressurization. 

    Apart from that these things sound awesome.