Overnight Sensation MTM build

[Kristian_AUS]

After much deliberation weeks ago and help from many forum members (thanks again!) regarding my 5.1 HT/music build I've started on the OS MTM's. They'll first be used as my mains and move to surround duty after I build a trio of Sunflowers (L/R/C).

After all I've purchased, the folks at the local hardware stores know me pretty well by now. This build also sidetracked me for a little while - I started to make my own router table which has been fun. Waiting for the laminate to dry on the top as I type.

I've sketched them up just to help me plan the build and I've stumbled across something I want to run by everyone. I'm going to put the ports on the front because they'll be close to my wall. When I lay out the ports I need to move the MTM up the baffle by 1" to make room for the ports. In the attached picture I have them 0.75" from the inner walls and just under 0.5" from the base. I remember reading that ports should be at least 1" away from surrounding surfaces. The ports themselves are also very close to each other. Thoughts?


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EDIT: I thought I'd add some more information to this thread about the tools/parts I purchased for anyone out there considering their first build. I know I spent quite a bit of time deliberating what I should buy and reading threads here about peoples experiences. I had an overseas move a few years ago and had to get rid of most of my tools, so I had to start almost from scratch. I purchased tools a little on the higher end of the price range as I'm planning on some renovations and wanted to make sure that they'd last. I was quite surprised that I bought most of my tools in retail stores, their prices were typically the same or sometimes cheaper than online.

Router: DeWalt DW618PKB Fixed/Plunge Base Kit, variable speed
- Bought from Home Depot for $199. Selling points to me were that the guides on the plunge base were larger in diameter than most of the other brands and had less play in them. The built in dust collection was also a selling point where for the others I looked at it wasn't offered, or was an additional accessory. They also have a 3yr warranty and free servicing in the first year.

Saw: Skil MAG77LT Worm Drive Saw
- Bought from Home Depot for $175. It was the cheapest worm drive saw I could find with a cast base. I wasn't particularly impressed with the quality of stamped bases I saw on some other saws. Anything that'll help to give me a cleaner, more accurate cut. Using a home made saw guide I've been able to get panels that fit together very well. However, I'd definitely recommend a table saw if you've got the money and space as I've found it takes me quite a bit of time to set up each cut.

Random Orbital Sander: DeWalt D26453K, variable speed
- Also bought from Home Depot. They had it advertised for $79. But they beat competitor's prices by 10% and the DeWalt outlet store had it for $74. So that coupled with a Home Depot credit card discount of 5% brought it down to $63. I was leaning towards a Bosch ROS20VSC as I read they were a little quieter, but I don't think the DeWalt is loud. What I didn't like about the Bosch was that its dust collector was a bit of a pain to open and close, where the DeWalt had a simpler twist off mechanism. The vacuum adapter on the DeWalt is also built in, where the Bosch is separate (but caters to 2 diameters).

Shop vac: Stanley Wet/Dry Vac, 10-Gals, 4-HP
- On special at True Value for $40. Works great as a shop vac, but I wasn't that impressed when I used it to extract dust with the plunge base router. From what I've read, the dust extraction on the DeWalt router works well so I'm guessing the flow on the vac is maybe a little sub par. I thought it'd suffice as it's more powerful than many other vacs out there in that price range. You get what you pay for I guess.

Veneer: www.veneersupplies.com
- Quite a few members purchase from here, and the prices/selection was great. The first order of walnut veneer was unfortunately damaged in transit but they were great about getting a replacement on its way to me.

Router bits: www.mlcswoodworking.com
- Once again, a tip from other members. The prices/selection was good and shipping is free. Much cheaper than the local hardware stores.

I'll post some pictures of the build as it progresses. Hopefully this will help any new diy'ers considering their first build.

[randyohoh]

Re: Overnight Sensation MTM build

You might consider a slot port which would need to have the same area and length as the two round ports. Hopefully one of the more experienced members will affirm this idea.

[Kristian_AUS]

Re: Overnight Sensation MTM build

You might consider a slot port which would need to have the same area and length as the two round ports. Hopefully one of the more experienced members will affirm this idea.

Thanks for chiming in, but I'm going to stick to round ports. Paul mentioned it can be done on his website, and another member has done it as well. I'm just curious about the position seeing that the guideline seems to be 1" from the wall and on this design it's difficult to achieve.

[Wolf]

Re: Overnight Sensation MTM build

After much deliberation weeks ago and help from many forum members (thanks again!) regarding my 5.1 HT/music build I've started on the OS MTM's. They'll first be used as my mains and move to surround duty after I build a trio of Sunflowers (L/R/C).

After all I've purchased, the folks at the local hardware stores know me pretty well by now. This build also sidetracked me for a little while - I started to make my own router table which has been fun. Waiting for the laminate to dry on the top as I type.

I've sketched them up just to help me plan the build and I've stumbled across something I want to run by everyone. I'm going to put the ports on the front because they'll be close to my wall. When I lay out the ports I need to move the MTM up the baffle by 1" to make room for the ports. In the attached picture I have them 0.75" from the inner walls and just under 0.5" from the base. I remember reading that ports should be at least 1" away from surrounding surfaces. The ports themselves are also very close to each other. Thoughts?

[ATTACH=CONFIG]45853[/ATTACH]

You probably won't get many answers for queries posted in the Gallery, which is for finished projects and links to write-ups. Try the TechTalk forum for questions.

Later,
Wolf

[Leroy R]

Re: Overnight Sensation MTM build

On 3/8/14 I replied to your PM with this message giving all the dimensions for port and driver placement.

Ok, I recalculated the dimensions. I used schedule 40 PVC for the ports mounted to the rear of the baffle, recessed about 1/2" into the baffle.

Layout of the baffle is center of the ports are 1 7/8" from the left edge of the baffle for the first port and 4 1/8" from the left edge of the baffle to the center of the second port. Both ports are 1 7/8 up from the bottom of the baffle.

The center of the lower woofer is 5.5" from the bottom of the baffle and 3" from the left edge of the baffle.
The center of the tweeter is 9" from the bottom of the baffle and 3.75" from either the left or right edge of the baffle depending on whether you are doing a right or left speaker.
The center of the upper woofer is 12.5" from the bottom of the baffle and 3" from the left edge of the baffle

The baffle is 6" wide and 16" tall. The overall box depth including baffle is 10" if building with 3/4" material. If you use 1/2" material the depth will be 8 1/2" and you will need to reduce the recess of the ports to 1/4" into the rear of the baffle and additional support toward the rear of the ports to keep them from breaking out of the baffle might be a good idea. I use the original polyurethane gorilla glue to glue my port tubes in. It expands so you want to clamp the tubes in place until the glue dries so it doesn't push them out.

I hope this helps. Let me know if you have any more questions.

I think the primary concern with ports is the space between the port opening inside the enclosure and the side that opening is facing. So in your case it would be the distance of the back of the port to the rear wall of the enclosure. That distance should be approximately the same or greater than the inside diameter of the port. If I remember correctly the ports in mine were almost touching the side walls and bottom of the cabinets. I can't remember if I did 3/8" or 1/2" round overs on the openings of the ports. Mine were a Christmas gift for my mom in Michigan so I don't have them handy. I just went back to Pauls page to get his enclosure dimensions again and recalculated all the dimensions again as if I were going to build another set and the above dimensions for driver and port locations are what I came up with.

https://sites.google.com/site/undefinition/overnightsensationmtm

Pics of the ones I built are at the end of this thread

http://techtalk.parts-express.com/showthread.php?223992-Following-suit-and-making-two-pair-of-overnight-sensations-my-second-build

[Kristian_AUS]

Re: Overnight Sensation MTM build

I modeled the PE adjustable length flanged ports but didn't like how they looked with the cut flange so I'm going to go with Lee's spacing as mentioned above using 40 PVC 1.25" ports.



I had a few other designs conjured up but thought I'd keep my first build a little simpler. This is the look I'm going for with a previous idea to the right. I'll be using walnut veneer and going for a polished black finish, either satin or gloss.

[Kristian_AUS]

Re: Overnight Sensation MTM build

The build is coming along really nicely. Finished my router table which I'm really glad that I made. I decided not to make a base which will make it easier to store, it just rests on two saw horses. It made flush trimming the finished boxes very easy. I thought about buying a table but I wanted a large work surface (2'x4') and most commercial offerings were quite pricey, and having a reason to spend more time in the garage isn't a bad thing either. I've just begun to make a fence for it.



One thing I think that I could have done better was the bracing. I'm using 3/4" MDF and according to Paul C. may not require bracing. I decided to put one in for safe measure and made a window brace which I put a little higher than the middle of the cabinet (due to moving the drivers up on the baffle to make space for the front ports - see Leroy R's build). In hindsight I would have just used a ~1.5" wide brace spanning the width of the cabinet instead. This would have allowed me to mount the cross-over midway up the back of the cabinet. Now I'm limited to the top and upper rear of the cabinet.



It's almost time to decide on which receiver to buy, I don't have anything to hook the speakers up to right now. I thought it was hard enough deciding which speakers to build but sifting through all the information on a receiver is rough. I've distanced myself from the tech world for a while and figuring out what I want now/might need in the future is proving a challenge. Room correction (the different levels of Audyssey, HK's EzEQII etc) not to mention networking, airplay, built in can openers...and time doesn't help me whittle down the selection, I've been finding more options I find - Emotiva which seems like great bang for the buck, and and and... I might start by deciding on which room correction seems the 'best' and go from there.

[Kristian_AUS]

Re: Overnight Sensation MTM build

Not much progress on the speaker front last night except for marking out the baffle for the cutouts and working on the fence for my router table.

I'm contemplating the order of the finishing steps for the cabinets. I'm planning on having a gloss black baffle and veneering the rest.

Either:
1) glue baffle, veneer the sides, trim the baffle, paint the baffle
or
2) veneer the cabinet, trim the baffle (before it's glued on), paint the baffle then glue it to the cabinet
or...?

While 2) may be a little finicky (lining up the baffle, glue squeezing out of the joint, ...) I think it may be easier to get a gloss finish on the baffle before it's attached. I'm concerned that with 1) it may be difficult to sand/polish the baffle close to the veneer. Any suggestions?

[Leroy R]

Re: Overnight Sensation MTM build

I typically apply the veneer to the cabinets before I attach the baffle. It makes trimming the veneer a lot easier. Apply blue painters tape to protect the veneer from glue squeeze out and glue the baffle on. Flush trim and round over the baffle leaving the blue tape on to protect the veneer from the router bearing. Remove the tape from the veneer and mask off the baffle. Apply stain and poly to the veneer. Once the poly is cured, apply tape and masking paper to protect the veneer and paint the baffle. I apply a couple coats of clear over the paint as well.

Here are some before and after shots of the Aurbacs I built.

[Leroy R]

Re: Overnight Sensation MTM build

Also if you can lay the baffle face down, apply the glue to the contact surfaces of the box and then set the box on the baffle and clamp it, the glue squeeze out will not run onto the veneer. It will pool at the joint or spill over onto the baffle where it can be trimmed or sanded off before painting. You still need to apply the painters paint to the veneer at the edge of the joint, but it eliminates the chance for the glue to run down the cabinet to the unprotected veneer before you can wipe it off.

[Kristian_AUS]

Re: Overnight Sensation MTM build

Thanks for the tips Lee! How was it polishing/sanding the baffle? I imagine that it would have been difficult to get the finish you did close to the paint/veneer transition. Did you use poly over the paint too - I was wondering if they were compatible?

[Leroy R]

Re: Overnight Sensation MTM build

rattle can clear enamel over the paint. I've used Krylon and Rustoleum and prefer the Krylon. It's easier to spray. I'm not sure if poly would react to enamel paint or not. Also not sure if you can spray the enamel clear over poly. When sanding between paint layers, you are using very fine grit and doing so very gently so isn't very hard to prevent damaging the tape. You should also be spraying very thin layers of paint. You may not even get full coverage until the second or third coat. After a couple coats of primer, a few coats of paint and a couple coats of clear you should be at about the same thickness as the poly. How good your seem is depends how straight your masking is.

[Wolf]

Re: Overnight Sensation MTM build

I've applied both brush-on and spray polyurethane over enamel paint. As far as wipe-on, make sure the paint is cured first.

Polyurethane will give a yellowish tinge (except over black), whereas Polycrylic will not.

Later,
Wolf

[Kristian_AUS]

Re: Overnight Sensation MTM build

Thanks for the tips. I bought a couple of rattle cans and plan do a few tests on scrap to see how they go on. I'm hoping that one type of clear will be compatible with both the stain and paint which might improve the finish and minimize seams.

Good tip Wolf, I didn't realize polyurethane gave a yellowish tinge. Do you mean that it's noticeable over paint (other than black) or also veneer?

[knowledgebass]

Re: Overnight Sensation MTM build

Polyurethane will yellow over time. Most will start out mostly clear, although the oil base ones may have a bit of a yellow hue. The water-base ones tend to start out clear and are more UV resistant (e.g. have more inhibitors). Hasn't happened to me yet, but it will still apparently yellow in time.

I'm unfamiliar with polycrylic. From the description and given the (R) mark Minwax includes after the word "Polycrylic," it sounds a lot like the water base polyurethane I've used from General Finishes. Don't take my word for it though, as I have no experience with it ;)