On the 8" day of Christmas...

[unclejunebug]

I started a project to design a subwoofer as a gift for a buddy of mine but had never done any design of my own. The project was an opportunity to get a little experience with using WinISD and Fusion 360 as I had never used either of these programs before. I got as far as I could on my own by following online tutorials and what not and started this thread a few months ago to fill in the gaps where I had questions or was just plain unsure of something.

Originally I was planning on doing the build as a surprise gift and was trying to base my design off of info I had gleaned from questions I asked about my friend's plans for living room renovations. Because of that I went from a standard enclosure to a low profile design. Ultimately I decided that designing something for renovations that were yet to be complete was a bad idea. I spilled the beans and was glad I did as his plans changed after knowing that a subwoofer was "en-route" and as an added bonus, his wife was on-board!!!!

With this new information I went back to a standard enclosure design. My goal was to keep the total build cost within a reasonable budget and fit in a relatively small enclosure while still ending up with something that would be worthwhile and sound/perform well. I got a lot of great help from the forum members here which was much appreciated! Wogg shared his Indy subwoofer design which fit the bill from a size constraint perspective and I ended up basing my design on his. Ultimately I wanted a down-firing sub so I made a few changes to the enclosure dimensions to accommodate that as well as placing the port on the rear of the enclosure and to slightly increase the internal volume. Here's what I came up with in Fusion 360...



The enclosure is 3/4" MDF with a double baffle. The port was moved to the rear of the enclosure and the amp turned sideways to make room. The enclosure will be painted white and it's going to stand on some 2" tall feet made of birch and stained with a dark tone (General Finishes Espresso). This color scheme matches my buddy's OS's that he built a few years back fairly well. I originally planned to rabbet all edges but decided against it due to time constraints. Instead I only rabbeted the bottom edge of each side so half off the double baffle would recess into the enclosure.

Over the past few weekends I got all the pieces cut, recesses trimmed out, and the enclosure assembled. I did run into a bit of a DOH! moment after rabbeting the sides. I did a dry fit and realized that I didn't want to make the rabbet run the length of each piece which left me with a 3/8" gap in each corner which you can see below. Lesson learned!



I filled the gaps with some tiny cut pieces of MDF, finished assembling the enclosure and flush trimmed the top and bottom pieces. The mounting ledge of the SA70 amp I'll be using was a bit taller than I expected so I nailed some 1/2" MDF onto the backside of where the amp will go to give me more material for the install screws. This also worked great as a guide for the bottom bearing flush trim bit used to cutout the amp opening. The pic below is as the enclosure stands now.



Since this is a gift I want it to look as good as possible which in my mind means NO SEAMS!!!! My next step is to follow this trench method I found for hiding b u t t joint seams. From the pictures it looks like a cove moulding bit is used and I don't currently have one so I'm in a bit of a holding pattern until one gets delivered, which should be tomorrow. I'll be racing to get this done before Christmas but it may end up becoming an "8" days of President's Day" build haha

EDIT: I failed to mention the components I'm using for this build. The amp is the Dayton SA70 and the subwoofer is the DCS205 8" sub. I originally planned to use the DCS205 but then went back and forth between that and the SD215A-88 from Wogg's build. I had settled on the SD215A and ordered one but eventually switched back last minute due to the Cone excursion graph I was getting with it in WinISD. In my thread linked above I was getting excursion above Xmax from 40-60Hz with the SD215A but none of that with the DCS205. From the feedback I got in that thread it wouldn't be damaging to the subwoofer itself but would rather add a little distortion at high volume. I don't know if that distortion would have even been discernable to the ear but since this was a gift and I had a way to remove that added distortion by going with the DCS205 I ultimately decided to do that.

[djg]

Too late for you now, but a simple method for a trench (actually v groove) is to put a small 45 degree chamfer on the appropriate edges before assembly so a v groove results upon assembly. I read that here on PETT.

[Steve Lee]

That is some good looking fabrication work.

[unclejunebug]

Too late for you now, but a simple method for a trench (actually v groove) is to put a small 45 degree chamfer on the appropriate edges before assembly so a v groove results upon assembly. I read that here on PETT.

Ah, thanks for the tip! My next project will be a sub for myself to replace my aging piece of turd MTX SW2. I might have to look into this depending on how the trench method goes on this one.

That is some good looking fabrication work.

Thanks! While I'm fairly please with how things have turned out so far there are a few things that the pictures don't quite show. That said I think I'll be happy with how it all turns out in the end.

[Steve Lee]

Just keep going and try to overlook the imperfections, Sir.
That thing (box) will not be visually scrutinized much if at all (once installed) and that is a fact we all need to get in our heads and to accept as DIY/builders.

I am STILL agonizing over a Samba kit build where I am still constructing the cabinets from scratch after a freaking year!

Why?

Because I keep coming back here and looking at all the awesome creations of others and find my efforts lacking in perfection.

I don't want to post my progress nor pictures because I fall so short of all those who have been doing this for far longer than I.


This is a HOBBY for most of us and the entire reason that PARTS EXPRESS EXISTS.

If a bunch of industry professionals/anal-ists [on this site] run-off all the wanna-be DIY market what purpose do they or this website serve?


Help and encourage one-another.

THAT is the explicit PURPOSE of this site.



Sorry for my little rant.

PTL and enjoy your awesome hobby.


Best!



Steve.

[unclejunebug]

Just keep going and try to overlook the imperfections, Sir.
That thing (box) will not be visually scrutinized much if at all (once installed) and that is a fact we all need to get in our heads and to accept as DIY/builders.

I am STILL agonizing over a Samba kit build where I am still constructing the cabinets from scratch after a freaking year!

Why?

Because I keep coming back here and looking at all the awesome creations of others and find my efforts lacking in perfection.

I don't want to post my progress nor pictures because I fall so short of all those who have been doing this for far longer than I.


This is a HOBBY for most of us and the entire reason that PARTS EXPRESS EXISTS.

If a bunch of industry professionals/anal-ists [on this site] run-off all the wanna-be DIY market what purpose do they or this website serve?


Help and encourage one-another.

THAT is the explicit PURPOSE of this site.



Sorry for my little rant.

PTL and enjoy your awesome hobby.


Best!


Steve.

Hey, I hear ya. I am a perfectionist to the N'th degree, most often to my detriment. It's one main reason why my wife hates doing renovation projects together haha. Ultimately I know that the little things that I see are things that most all others would never ever notice or even care about in a million years but still hard to overlook for myself. It's a good reminder though just to keep on working and enjoy the process rather than obsess over the minutia. Fingers crossed! I'm gonna have to if I want to be done in 10 days.

[unclejunebug]

Made a fair bit of progress over the past few weeks but things are coming down to the wire! I wanted no visible seams and went with the trench method to hide them. I've only used bondo once before so I am by no means an expert with it and while I think the final result will look great, I grossly underestimated the amount of work that goes into this method. Someone with more experience would likely be much quicker but man, I had a heck of a time getting the trenches completely filled and flat. What I thought would have taken part of a day ended up taking part of three or four days.

Here are some routed trenches. I don't think I quite went the prescribed 1/8" deep but I also didn't want to have to build up too much with the bondo. Had to go a bit more shallow around the port opening to be safe...



I put down three applications of bondo total with sanding in between and after the third one I still had visible dips where some of the trenches were. I would smear it on and initially it would look good but then a few minutes later the bondo would seemingly "bottom out" and the dip would be visible again. Eventually I got tired of mixing and sanding the darn stuff (makes a TON of dust). I had most of the trenches filled with the bondo so I decided to fill in the rest of the gaps with wood filler. After one coat I was pretty much there...



At this point I was ready to round over the edges and went with a 3/8" roundover. Unfortunately I wasn't quite done with the bondo as I needed more for the newly rounded edges...

[unclejunebug]

Throughout the bondo sanding process I got a little rowdy with some 80 grit sandpaper and had quite a few visible scratches from it. They looked deep enough and were plentiful. After spending all that time making the seams disappear I wasn't about to have sanding scratches show up in my paint. To get rid of them I decided to just coat the whole thing in glazing putty and sanded with 400 grit. After the final sanding the enclosure wasn't that pretty to look at but it was baby's bottom smoooooooooth...

​​

Since I'm short on time I wanted to be able to paint all sides simultaneously. I had some scrap boards and plywood that I used to make a paint stand. I hit it with with two coats of aerosol Zinsser B-I-N with some 400 grit sanding in between coats and after. I followed that up with two coats of white semi-gloss spray paint and this is where I'm at now. I'm very pleased with how it's looking.



I had some tack cloth fibers show up on the top of the enclosure in the second coat of paint which is a bummer. I'll have to sand those off lightly and respray a bit. I'm hoping that I'll have time tomorrow to finish the assembly. I plan to line the inside walls with some foam and then I'll just need to drop in the port, amp, and sub and I'll be all done! I just might make Christmas after all!!!

[Steve Lee]

Your friend is going to be very pleased to have such an heirloom as this creation, Sir!

Outstanding effort.

:D

[unclejunebug]

Your friend is going to be very pleased to have such an heirloom as this creation, Sir!

Outstanding effort.

:D

Thanks, Steve! I'm very happy with how it turned out. It's been a lot of work but a learning experience for the next one .

[unclejunebug]

I had some time this morning and was able to finish up the sub before Christmas! I lined the inside with some dampening foam and then dropped in the port, amp, and the sub itself. The port is tuned to about 32Hz. After that I attached the feet to the bottom with some pocket hole screws. The feet were made out of birch, stained espresso, and finished with a satin clear. After they were attached I covered the bottom with some brown protective felt.




Here it is all done! I am really happy with how it turned out. Always nice to see something from start to finish and have it end up close to what you were you expecting haha. I did a quick sound check and watched a bit of the Mines of Moria scene from LOTR: The Fellowship of the Ring. I am pretty impressed with what this thing can put out considering it's an 8" sub and it will be a great improvement to my buddy's system since he's currently sub-less. Merry Christmas everyone!

[trevordj]

It looks great! Well done. Be careful with the glazing putty. The uncatalyzed stuff can cause staining through some paints which won’t show up for awhile. I did the trench method on my subwoofer boxes but I won’t do it again. The amount of effort to make the joints disappear is just too much. A much easier way to hide the joints is to simply do 45 degree miters or, my preference, lock miters. But, I have never tried doing a round over over the miter. I have seen people do a round over right up to the joint and that seems to work as well. -Trevor

[unclejunebug]

It looks great! Well done. Be careful with the glazing putty. The uncatalyzed stuff can cause staining through some paints which won’t show up for awhile. I did the trench method on my subwoofer boxes but I won’t do it again. The amount of effort to make the joints disappear is just too much. A much easier way to hide the joints is to simply do 45 degree miters or, my preference, lock miters. But, I have never tried doing a round over over the miter. I have seen people do a round over right up to the joint and that seems to work as well. -Trevor

Thanks, Trevor! I wasn’t aware of that potential issue with the glazing putty. I guess time will tell if it shows through. There wasn’t that much of it left after sanding and I’m hoping the BIN primer will seal it enough to where it won’t be an issue.

I haven’t heard of the lock miter bits before and they look like they make great joints but seem very tricky to setup. I think to try out that method I’d need a much more sophisticated router table. A precision lift seems like it would be a huge help as well.

[trevordj]

Thanks, Trevor! I wasn’t aware of that potential issue with the glazing putty. I guess time will tell if it shows through. There wasn’t that much of it left after sanding and I’m hoping the BIN primer will seal it enough to where it won’t be an issue. I haven’t heard of the lock miter bits before and they look like they make great joints but seem very tricky to setup. I think to try out that method I’d need a much more sophisticated router table. A precision lift seems like it would be a huge help as well.

Oh ya, definitely a router table with fine adjustment is necessary for the lock miter. I also found the infinity tools meter setup jig to be worth its weight in gold for the setup.

If you don’t have a fine adjustment on your router table than a regular miter is much more obtainable (either on the table saw or with the router). You could always reinforce it with a spline, dominoes, or biscuits. Just something to thing about for the future. It looks great though! Very well done indeed.

-Trevor

[unclejunebug]

Oh ya, definitely a router table with fine adjustment is necessary for the lock miter. I also found the infinity tools meter setup jig to be worth its weight in gold for the setup.

If you don’t have a fine adjustment on your router table than a regular miter is much more obtainable (either on the table saw or with the router). You could always reinforce it with a spline, dominoes, or biscuits. Just something to thing about for the future. It looks great though! Very well done indeed.

-Trevor

I think for the next project I might do mitered edges with biscuits and then round that over. Im thinking if the seams are within the round over they may not bother me so much.