First build - Overnight Sensation MTM

[DIYTodd]

This is my first speaker build except for a few car audio subwoofer boxes I made in my youth. I've had a dormant interest in DIY audio for around 20 years. I've always wanted to build and eventually design my own speakers. Audio and woodworking are both of interest to me so DIY speakers are the perfect fit. Up until now my only woodworking experience has been of the carpentry variety. My knowledge and skill in fine woodworking are yet to be developed. I recently acquired a new to me Delta Unisaw. Now that I've built the projects for my kids school that paid for the saw I can turn my attention to speaker building. I didn't know about this forum when I was first looking for designs to try. I happened to come across Paul Carmody's web site from a link I found somewhere. After browsing through his designs I decided that the Overnight Sensation MTM looked like a good first project. When ordering the parts I noticed these forums; now I understand what the PE forums are that people kept talking about. After perusing the forums here I'm excited by all the other potential designs. Somehow I'm going to need to find an extra income to support this hobby. As I type this my parts haven't arrived but I did start enclosure construction last night. I cut all the sides to length and rabbeted the corners. I took the rabbets into account and changed the appropriate measurements to keep the interior volume the same. I've read posts indicating that simple but-t joints are adequate. I did the rabbets because I wanted to practice with the dado set that came with my saw; they also seem to ease assembly. I bought a circle jig and a Bosch router as well but I was stuck when I found I didn't have a 1/8" bit to drill the pilot holes for the circle jig. It was about 2:00 AM when I discovered this so I had to stop for the night. I work night shift and on my days off I still sleep in the day and do things at night to make it easier on me. Unfortunately this often means if I don't have everything I need I'm often stuck until the next day.

[Chris Roemer]

Re: First build - Overnight Sensation MTM



That's how I like to build 'em too.
Make my rabbets w/a router - VERY clean.

[DIYTodd]

Re: First build - Overnight Sensation MTM

I was able to try out the Jasper circle jig tonight. It works really well, so much dust though. I did notice after I routed the hole for the binding post cup that it took a lot of material out of the back of the speaker. If I'd ordered the type where only the shafts are drilled through it would preserve some stiffness. Oh well, first project, you live and learn. I was also a little too eager to rout the vent holes. I had intended to make them the inside diameter of the PVC with a rabbet on the inside of the box that the outside of the pipe would slip into. That way less PVC would be exposed and I could round over the outside edge. Instead I routed them the outside diameter of the PVC. It will still work, just not the detail I had intended. If I have time I'll build the crossovers tonight as well so I can start finish prep. I bought some cherry veneer I intend to put on the sides and top. I want a black baffle for sure, I may also paint the back and bottom black since they will never be seen. If I do that I will have more veneer left for other projects.

[DIYTodd]

Re: First build - Overnight Sensation MTM

Built the crossovers tonight. Everything straight from the BOM except the 10 Ohm resistor. The one on the BOM was out of stock so I ordered a different brand. The suggested layout seemed well thought out so I went with that.

[Chris Roemer]

Re: First build - Overnight Sensation MTM

Nice.

[nikkoluvr]

Re: First build - Overnight Sensation MTM

welcome back to the addiction.........er, hobby I too have a Delta Unisaw, and love it. I've built the OS MTM's, OS's, as well as Paul's Core's. You will enjoy them, they are fun to listen to. What do you plan to dress them up in? My OS MTM's are in pommele Makore (not quite finished, of course), and I did the OS TM's for my son in Afromosia, if I remember correctly. The core's are in the much used "raw MDF" that so many of us use!
nikkoluvr

[DIYTodd]

Re: First build - Overnight Sensation MTM

The plan is black baffle with cherry veneer on the sides and top. I think I'll go black on the back and bottom as well since they will never be seen. I'm kind of in a hurry to try them so I think the finish may not get all the love it would otherwise.

[DIYTodd]

Re: First build - Overnight Sensation MTM

I test fit all the components then glued the front and back on. The crossover will fit through the driver opening so I'll install it later. I've Bondo'd the defects and sanded prior to priming. MDF can be annoying, I set them down wrong and there isn't a sharp corner anymore. I thought I'd made a mistake earlier by routing the vent holes so the PVC cam all the way to the surface. I think now it's better than my earlier plan. I used a 1/4 roundover on the PVC and it routed perfectly. A small amount of Bondo to fill the micro holes around the edge and it came out great.

[JDCrae]

Re: First build - Overnight Sensation MTM

Looks really nice!

[DIYTodd]

Re: First build - Overnight Sensation MTM

I gap filled with Bondo and primed with Duplicolor scratch filling primer. I've never painted on MDF/Bondo/Primer so I wasn't sure how perfect it needed to be. After applying paint I learned it needs to be absolutely perfect or you can see the blemishes. Now I know. I wanted to paint the black portions with Krylon Fusion satin black but they didn't have any at Lowes. I bought the two other products pictured to give them a try. After spending most of the night trying to get them right I wish I'd looked at another store and found the Krylon Fusion. The following night I sanded the imperfections out of the Rustoleum finish and applied the Krylon I had gone in search of. Much better finish and great dry times. I apparently have the dustiest house there is because I cannot keep bits of dust out of the finish as it dries. I'm just going to have to settle for "good enough" Someday maybe I'll have a dust free painting area. After the paint dried I tried my hand at veneer following this tutorial. I applied cherry I picked up at woodcraft. Overall the veneering has gone much more smoothly than the painting. I thought I'd try my wife's paper cutter to rough cut the veneer, it worked really well. I only had time to do one tonight, unfortunately I work tomorrow night so it might be a while before the other gets veneered. I plan to finish them simply with a few coats of Arm-R-Seal.

[Kevin Wehrle]

Re: First build - Overnight Sensation MTM

Looks great. I enjoyed building mine and they make a nice set of office speakers.

[Philzeemon]

Re: First build - Overnight Sensation MTM

DIYTodd...

Good choice on a First Build...you will be impressed with the OS-MTM's capabilities... I look forward to seeing them completed. Thanks for the build thread and your posting.

[DIYTodd]

Re: First build - Overnight Sensation MTM

I sacrificed a little sleep before work to get all the veneer applied. I temporarily mounted the drivers to see what they would look like complete. There isn't any finish on the veneer yet.

[DIYTodd]

Re: First build - Overnight Sensation MTM

With one coat of Arm R Seal. The finish actually looks a little better in person. I think I'll do the recommended 3 coats.

[DIYTodd]

Re: First build - Overnight Sensation MTM

Finally finished. For the most part I'm quite happy. The biggest problem came from my decision to paint part and veneer part. I couldn't decide to veneer first then mask and paint or paint then veneer. I decided to paint first. I ended up with a few scratches and nicks in the paint from the veneering process. That is my fault, I should have masked off the paint entirely once it was dry. I also had the front baffle glued on during the whole process. If would have saved a lot of problems if I attached it later so I could paint and veneer simultaneously rather than wait for one to finish then moving on. I think I was worried about getting the baffle properly attached with all the finishes in place, but I don't think that would have been a big deal. After routing the hole for the terminals I realized it was a big hole and some simple through-the-wood terminals may have been a better choice. I doubt it will really matter but I can see why so many projects have them. After some false starts I used Krylon Fusion black satin for the painted areas. I think that will be my go-to paint until I get an HVLP gun. I couldn't decide if I wanted satin or flat so I went satin. I think now I may have preferred flat. Actually, I think I want something between pure flat and satin but I couldn't find that in Krylon fusion. I put some felt pads on the bottom so they are slightly isolated from the surface thy sit on.

As for listening they sound great. Unfortunately, I don't have anything else here at home except headphones to audition them against. That's the main reason I wanted to build speakers, I don't have any. I've tried them with my old Sansui 1000A tube receiver with great results. The Sansui has been sitting for about a decade since I last used it. It looks like I need to recap it, one of the output tubes will red plate after about 10 minutes. I don't think it has anything to do with the speakers, it's always the same tube. Fortunately I was worried about something like that happening and was watching the tubes very closely the whole time. I ordered a SMSL SA-60 which also seems to work really well. Since these will probably end up on my desk the SA-60 will most likely be their main source of amplification. My son is already talking about what we are going to make for him. I'm excited to try other designs. Thanks to Paul C for all the work he put into these designs we all enjoy.