Yet Another Four Dayton Audio Ultimax UM18-22 18" Sealed Build

AdamAttewell

Well-known Member
Hello all,

Just about to start building my first subwoofers which will be four Dayton Audio UM18-22's in sealed cabinets.

These will be replacing the two SVS PB16's I had previously so am hoping these are going to be a worthwhile upgrade.

Seeing as these are the first subwoofers I have ever built I did not trust myself to cut to the MDF for the cabinets so I purchased the Denovo Audio flat pack cabinets.

Everything arrived yesterday from Sound Imports except for one of the drivers which is in Northampton & I am in Nottingham so looks like that wont arrive till Monday now.

I know this is a pretty common build but if anyone has any advice or tips please do feel free to chime in as I am learning as I go here :D

Many thanks for all the help & advice in advance, I will be updating this thread regularly with my progress & pictures.

Wish me luck

Adam
 

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xxGBHxx

Well-known Member
Take your time, don't rush, enjoy the process. Any bit's you're not 100% sure of don't guess just ask in here there's some very knowledgeable and experienced people here who are happy to help (unless you're skilled enough to dig yourself out the ensuing mess! ;))

Good luck

G
 

AdamAttewell

Well-known Member
Many thanks G for your message I have just started gluing the braces to the back of the cabinet.

I am following the Part Express video on YouTube made a slight error & clamped the wrong braces down to start with as you can see in the picture with four clamps in position.

Hopefully no harm no foul as I have now moved the clamps to the cross brace instead.

Never used this Titebond Ultimate wood glue before, its very thin compared to the wood glue I normally use.

Starting to worry I won’t have enough glue in this 946ml bottle & can’t get any quickly.

What do you guys think? Should this bottle be enough for four subs?

If not will any wood glue work or do I need to buy a specific kind?
 

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xxGBHxx

Well-known Member
Many thanks G for your message I have just started gluing the braces to the back of the cabinet.

I am following the Part Express video on YouTube made a slight error & clamped the wrong braces down to start with as you can see in the picture with four clamps in position.

Hopefully no harm no foul as I have now moved the clamps to the cross brace instead.

Never used this Titebond Ultimate wood glue before, its very thin compared to the wood glue I normally use.

Starting to worry I won’t have enough glue in this 946ml bottle & can’t get any quickly.

What do you guys think? Should this bottle be enough for four subs?

If not will any wood glue work or do I need to buy a specific kind?
Titebond has an excellent reputation generally so I wouldn't worry about it. It's used by many professional carpenters especially in the US. 1L will go a long way so more than enough I would think.

That said any will do. Personally I swear by Gorilla Wood Glue. Similar to PVA in consistency but very strong. Amazon have 1L of it on next day Prime for about £8. From bitter experience I know the bond is stronger than a 2*4 C24 joist.

One tip I did pop up somewhere else on here. If you have an edge of an MDF board to glue (e.g. where corners meet) run a thin bead of glue down the edge and rub it in with your finger then leave it dry for 10 mins. Go back, re-glue it and it makes for a much stronger bond. End "grain" on MDF is extremely porous so doing this allows the glue to soak in and makes for a much stronger bond.

G
 

AdamAttewell

Well-known Member
Titebond has an excellent reputation generally so I wouldn't worry about it. It's used by many professional carpenters especially in the US. 1L will go a long way so more than enough I would think.

That said any will do. Personally I swear by Gorilla Wood Glue. Similar to PVA in consistency but very strong. Amazon have 1L of it on next day Prime for about £8. From bitter experience I know the bond is stronger than a 2*4 C24 joist.

One tip I did pop up somewhere else on here. If you have an edge of an MDF board to glue (e.g. where corners meet) run a thin bead of glue down the edge and rub it in with your finger then leave it dry for 10 mins. Go back, re-glue it and it makes for a much stronger bond. End "grain" on MDF is extremely porous so doing this allows the glue to soak in and makes for a much stronger bond.

G
Thanks for the info G, I will order the 1L bottle of Gorilla Glue off Amazon for £8.36 just in case I run out. I probably won’t but I always buy to much of this kind of stuff:D

Never knew about that tip, so you put glue on the edges of the wood first & let it dry & then apply more glue & then attach both peices together?
 

xxGBHxx

Well-known Member
:)

So where you are attaching 2 sides like this |_ the "edge" will butt against the "face" so you have a very thin piece (18mm wide strip if it's 18mm thick board) sticking onto a face. That 18mm edge (or whatever thickness the board is) is particularly porus because it's been cut/shaped, especially with MDF. Pre-gluing allows the glue to soak into that exposed narrow edge and basically stops so much of the glue soaking into the MDF and weakening the joint.

The reason it's only 10 mins is because you don't want the glue to dry, you want it to go tacky (the exact same principle you use by applying PVA to a wall before you plaster to help suction) and it will still bond with the fresh glue you apply. You then get a really deep strong bond that will break the wood before the joint breaks.

Does that help?

G
 

AdamAttewell

Well-known Member
:)

So where you are attaching 2 sides like this |_ the "edge" will butt against the "face" so you have a very thin piece (18mm wide strip if it's 18mm thick board) sticking onto a face. That 18mm edge (or whatever thickness the board is) is particularly porus because it's been cut/shaped, especially with MDF. Pre-gluing allows the glue to soak into that exposed narrow edge and basically stops so much of the glue soaking into the MDF and weakening the joint.

The reason it's only 10 mins is because you don't want the glue to dry, you want it to go tacky (the exact same principle you use by applying PVA to a wall before you plaster to help suction) and it will still bond with the fresh glue you apply. You then get a really deep strong bond that will break the wood before the joint breaks.

Does that help?

G
Yes thanks very much for explaining further, I will do that from now on with the remaining three cabinets.

Hopefully this first cabinet one will be OK even though I did not prime the faces.
 

xxGBHxx

Well-known Member
Yes thanks very much for explaining further, I will do that from now on with the remaining three cabinets.

Hopefully this first cabinet one will be OK even though I did not prime the faces.
Yeh it'll be fine. I'm just a "over the top" kind of DIYer and over specify everything I make/build. My cinema room, for example, is so well built nothing short of a small tactical nuke is going to take it down ;)

G
 

AdamAttewell

Well-known Member
Not made much progress unfortunately due to family & chasing down where the hell DPD have delivered the fourth driver.

I have hit a slight problem though with the front baffle, I can get it to fit but I have to slide it into position with a clamp it's so tight.

This is going to be a right pain when a cover the mating surfaces with glue as it will push it all off.

I guess I have used to much clamping pressure when gluing the sides on making the gap slightly to small?

So what are my options? I with thinking of sanding down one edge of the front baffle but am concerned I wont get it very straight.

Cutting a millimetre off the edge with my table saw will be next to impossible.

Any ideas?
 

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mattkhan

Distinguished Member
Flush trim router bit does the job but I guess you don't have a router?

Gluing with the piece in position but not glued is the way forward for the next one :)
 

AdamAttewell

Well-known Member
Flush trim router bit does the job but I guess you don't have a router?

Gluing with the piece in position but not glued is the way forward for the next one :)
Hello Matt,

Yes I don't have a router, I ordered one yesterday with some bits, should arrive tomorrow.

I decided to sand the front baffle slightly by hand with a block & that did the trick.

I only needed to take about half a millimetre off & it fits in very snug.

Regarding the flush trim bit I thought that would not work in this scenario?

Never used one but from watching videos it seems that the bearing on the bottom of the bit rests on top of the piece of wood you wish to be flush with?

Here the wood is sort of trapped between the two sides of the cabinet, running a flush trim bit down the side of the front baffle would not work as what the bearing is resting on is already flush?

Probably did a totally crap job of explaining what I meant :facepalm:

I have included a photo of how the front baffle is trapped between the sides.

I had the same thought about the next three cabinets & having the front baffle in place before clamping the sides together.

Would I not be in the same position though as I would imagine that if I glue & clamp everything together with the font baffle in place & then try to remove it after the glue has dried on the side panels it will be well & truly wedged between the sides?

Only way around it I can see is to glue the sides & front baffle all at the same time but I don't know if I would be able to before the glue starts to set.
 

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mattkhan

Distinguished Member
A flush trim bit just needs an edge against which to trim, any old edge will do if need be

If you clamp at a point with no, or insufficient, resistance against the clamp then things go out of alignment. Ultimately you only need to hold it firmly into position til the glue sets so it sounds like you might be clamping too hard and/or have the clamp placed incorrectly.
 

AdamAttewell

Well-known Member
A flush trim bit just needs an edge against which to trim, any old edge will do if need be

If you clamp at a point with no, or insufficient, resistance against the clamp then things go out of alignment. Ultimately you only need to hold it firmly into position til the glue sets so it sounds like you might be clamping too hard and/or have the clamp placed incorrectly.
I think you are right I am clamping to hard, I will ease off with them on the next cabinet.

Thinking of using my brad nailer in combination with the clamps.
 

xxGBHxx

Well-known Member
I think you are right I am clamping to hard, I will ease off with them on the next cabinet.

Thinking of using my brad nailer in combination with the clamps.
Popping a couple of brads in before you clamp generally stops the surfaces shifting due to the clamping.


I use the Quick Grip ones and even with such a low pressure when I glue two wide surfaces together they still shift easily as the surfaces slide out of alignment when they displace the glue. A couple of brads sorts it or side clamping if you have bid enough clamps.

G
 

AdamAttewell

Well-known Member
Sorry for the lack of updates, progress has been slow but I would rather take my take my time & make as few cock ups as possible :D

I have finished gluing together cabinets 1, 2 & 3 with hopes tomorrow I can get cabinet four built tomorrow.

I have started looking at how I am going to get all the edges smooth as I think its very difficult to get a perfect cube that will need no sanding or trimming. You probably can but my D.I.Y skills are not sufficient enough :D

I was going to sand everything flush but I am thinking this will take quite some time & my neighbours are going to want to kill me when I am finished.

So as Matt alluded to earlier the flush trim bit seems a great option but I can see an issue with the front baffle.

I have attached an image I have labelled, hopefully this will make it easier for me to explain what I think will be the problem with using the flush trim bit.

If I run the flush trim but down edge 1 I will also need to run the flush trim bit down edge 2 which will effect 3 the rounded over edge.

I found it very difficult even with brad nails & clamps to get the second piece of the front baffle to be exactly in exactly the right place due to how it floats around on the glue when you clamp it down or moves a little when you fire a brad nail in.

There is also a slight tolerances in the cuts as they are slightly to big (I am talking 1 mm or under)

Due to the slightly wonky front baffle piece when I run the flush trim bit down edge 2 I am going to flatten off the rounded edge by an uneven amount so the amount of material removed from the rounded edge will be different from on one end to the other.

This will look strange as it wont be even across this entire edge so was thinking I will need to use a round over bit to fix this?

Problem is the radius of the rounded edge is bigger than any of the round over bits I have with 1/2" being the largest.

How do I find out what size round over bit I require or am I approaching this entirely the wrong way?
 

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AdamAttewell

Well-known Member
I don't understand how you have got to wanting to flush trim an already rounded over edge?
I need to flush trim or sand that rounded over edge as it is not flush with the side of the cabinet.

There is a lip caused by the edge of the front baffle overhanging the edge of the box. Only very slightly but there is a lip there.
 

mattkhan

Distinguished Member
I would trim it off and then decide how it looks while bearing in mind that there is very real potential to make it worse if you attempt to fix it. Ultimately once you paint it and stick it in a room then probably you won't notice it anyway.
 

xxGBHxx

Well-known Member
OK.

There are two ways.

The way I'd do it is to use a filler (Toupret is my recommendation but any wood filler will do) and use that to fill the ridges/gaps. Feather the edge and then sand smooth with a 320 or 400 grit paper. This will get you an almost perfectly flat surface. While this will mean your surface isn't perfectly square it works because your ridge is small and on a very large surface with a carefully feathered/sanded edge once painted will be impossible to see.

Second is to flush trim and then re-round the edge. This is more fraught with problems because of the way they've been rounded (It's an odd design choice to use a 18mm round on an 18mm board). I tend to agree with @mattkhan that you'll almost definitely never notice it once it's done, it's painted and you leave it 2-3 weeks.

On a dside note I'm always a little confused how some people obsess and go to massive lengths and time/money to achieve absolute perfection on these builds. Different strokes I appreciate but when I go and watch a film in my cinema, I'm not sitting there worrying about the fact I chipped some the MDF off my cabinets as I carried them down the stairs. Indeed even after I purposely "bodged" the attaching of velvet to the tops of them by joining 2 scraps together with staples I never ever notice even when they're only 8cm below my screen. Yes, it's good to strive for perfection but I'm not there to stare and obsess over the perfect finish on my speakers, I'm there to watch a film. Indeed I would even go as far as to suggest if anyone is worrying about having perfectly finished anything in a cinema (especially if it's a dedicated cinema) they are absolutely focussing on the wrong thing completely.

Back on topic. I'd suggest the first option but the second will also likely work.

G
 

AdamAttewell

Well-known Member
So made much progress over the last couple of days, I flush trimmed all the edges & then rounded them over.

I ended up blending the different radius's of the front baffle & sides by hand with sand paper which turned out great.

I also rounded over the lip that surrounds the driver which looks very nice. I did not take any pictures as it was very late & light conditions were bad. I will get some up shortly.

I also got one of the plate amp holes cut, just three more to go:D

Question regarding feet, I was planning to run no feet and just sit them on my carpet like I did with my SVS subs.

I see many use the Dayton rubber feet or spikes, what would you guys recommend?

I would of thought decoupling the sub from the floor was a bad idea as I want to feel that tactile feedback?

Was looking to either use these spikes:

M8 Speaker Spikes for Speakers Stands & Subwoofers (X8) Fits Atacama & Mission 700220131583 | eBay

Or these rubber feet:

Adam Hall hardware - set of black rubber feet, in a bag Set of 8 38 x 15 mm Black: Amazon.co.uk: Musical Instruments

But if I won't gain any advantage I will save myself the hassle of installing them :laugh:
 

xxGBHxx

Well-known Member
Pictures or it never happened ;)

Sounds great.

I actually drilled and prepared for some spiked feet but in the end I never actually fitted them. Like you my two go onto carpet and I really needed as much gap under the screen as I could get so I just decided not to use them in the end. I didn't even bother trying to compare with or without so I don't even know if it would make any difference to the sound either.

All I know is that the bass is monstrous and I'm happy with that.

G
 

AdamAttewell

Well-known Member
OK so some pictures of my current progress, got all the holes now cut for the plate amps.

It been a day of measure, measure, measure & then measure again :D

I used a jigsaw & a long piece of wood as a fence clamped to the cabinet to get a nice straight cut, I could of cut free hand as there is plenty of room for error with how large the flange on the plate amp.

So I am now ready for paint but & thinking of filling in the divots created by the brad nails before starting the DuraTex.

Last thing I want to do it start painting for you to be able to see where the brad nails are.

I was going to use wood glue & MDF dust as a filler but it does not work very well. I do have some wood filler but I read that you can only use vinyl based filler as DuraTex wont stick to acrylic based fillers?

On the manufactures website it states that no primer is needed if applying it directly to wood.

I see some use a 50/50 mix of wood glue & water to seal up the MDF before painting to stop telegraphing but it seems the manufacturer thinks this is not necessary with DuraTex?

I get the impression that DuraTex is so thick that is covers many imperfections & with me rollering it on which causes an irregular pattern you wont be able to see them?

Never used this stuff before so its I am guessing here :D
 

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