WMTMW Teaser

I love getting parts-express deliveries Guess what I'm gonna build!

NOTE: There are some extra parts here...




All I need is the wood and I'll get crackin.

As far as the crossover, I don't think he ever did the tweaking beyond what the htguide thread discusses. I'm doing the WMTMW arrangement for half for looks and half for functionality. My center channel (To Be Built) won't have the height of the tweeter in WWMTM, and figured I'd keep them as close to the same height as I can (for what its worth).

Since my receiver (Yamaha RX-V765) doesn't have the guts to drive sub-4ohm speakers to high levels, I will be driving these with a Stewart PA1000 power amp from the pre-outs on the receiver.

Hopefully, I can keep progress on this moving quickly enough to be interesting.

Here is the design I have in mind:



Constructed of 3/4 inch mdf. Painted with satin or flat latex interior paint to match the color of my unfinished birch TV stand (pics in one of my older threads). The port is on the bottom of the main enclosure supported off the base by threaded rod encased by PVC pipe (also like my tv stand). The grill is TBD for now. I may like the looks without it.

I was going to go with a solid wood (knot-free pine) enclosure, but after reading lots of other people posing the same question, they were encouraged to use mdf instead to avoid problems with warping, cracking, and humidity.

I have cut most of the larger pieces, and will do some work with the radial arm saw to cut the rest this afternoon.

Enclosures under way! Made some progress yesterday. These things are going to be bigger and heavier than I thought they'd be.



And I never seem to have enough clamps. Thank goodness for brad nailers. I only use brads where the nail will not be routed or cut later, and there are some things that are much to difficult with clamps alone. Hope to get baffles routed and port tubes installed this afternoon.

The whole family has been sick for most of a week, but I finally managed to get some progress made. Time for a much needed update.

One thing I learned was that sheet mdf can have a natural bow to it. While I didn't notice when I built my tritrix speakers a while back (likely because they were much smaller), these larger towers showed some considerable bow to them when I was getting ready to clue the front/rear panels on. Had I noticed before I had done some of the construction, I would have had the curves oppose each other so it would end ups straight in the end. But I didn't, and thus they needed to be held straight for gluing. See my method of straightening below: Note, that is a piece of 3/4 in 1x6 oak that I bent against it...



I did use my 18 ga finish nailer to help move the process along here, too. Once everything was dry, I flush-trimmed all edges, cut all the driver holes, and put a 1/2 inch roundover on all sides. Here's where they stand as of now:



I used a 50/50 mix of wood glue and water to help seal the edges. I used this on my sub build and it worked quite well at preventing the paint from soaking into the cut edges. They stand 44 inches tall right now, will be 50 inches tall when done.

I was going to use regular black ABS for the ports, but didn't want to hassle with it and ordered some 3" precision ports as per mpotoka's parts list.

Next steps will be installing the ports, finishing the base-plates, then building the crossovers.

Crossovers assembled (not soldered yet):



The two on the right are for the Woofers, and the two boards on the left are combined Mids/Tweets.

Crossovers are probably my least favorite speaker building item to spend time on. I was going to make them all pretty with the solders and wires all hidden under the boards, but said, "screw it". No one will see these anyways... I hope to solder them up this afternoon.

Okay, so yesterday I managed to get the crossovers soldered and do a quick speaker polarity check with a AA batt to make sure the speakers were wired correctly.

Now for a noob question. Does it matter how the wires go to the crossover from the amp? Of course I would keep both speakers identical, but does it matter which line the red/black goes to? Here's the crossover pic:



Which line off of the source is red/black, and which side of the speaker is pos/neg? The tritrix build I did before had too much info and videos for me to have gotten this wrong, but this build is a bit more demanding for me.

Brian

Ok, thanks. Is it standard crossover design, then, for the black/neg to be the unaltered common line to all the drivers?

That did answer my question, thanks!

This is a dayton classic wmtmw. Google it and you'll see the htguide post which has the most comprehensive thread on it's design. Credit goes to mpotoka for the design. He has a thread here too.

Here is the link.

http://www.htguide.com/forum/showthread.php4?t=32615

Sorry about the double post, doing this from my phone.

And the plus/minus on the schematic means in or out of phase? Good to know.

I remember the crossover having some adjustability with changing the resistors, so I'm building them per the BOM and see how they sound.

I'm still waiting on a pm from mpotoka through htguide to clarify the series/parallel wiring question.

Thanks for your interpretation. Any help from some one experienced helps.

Just a quick update. The base plates are ready and as soon as I get some decent weather (without any chores taking priority) I will give these things a shot of primer.

And I have received clarification about the wiring: The woofers are in parallel and the mids are in series.

So, going slower than I'd hoped, but I'll get them finished eventually...

DONE! For now..



They are together and functioning. I am leaving them unpainted for now. I want to give them a color that will match/blend in with my future media room. So until that happens I'll have unfinished mdf (thankfully my awesome wife doesn't mind).

They sound real good. Running them through a Stewart PA1000 power amp using the pre-outs on my receiver (with RCA to XLR adapter cables). I still need to take some time adjusting them a bit and finding a good crossover point for the sub, but first impressions have been good.

Note that I used the filter BOM as posted on htguide when I started the build. I did not notice that the posted schematic--which is the most current filter he uses--is slightly different than the BOM. But to my untrained ears, the schematic built with the BOM components still sounds good

Got to love it, though. I built these to be big, sweet home theater speakers, and the first thing they get used for is watching Backyardigans with my daughter.

I'll give my two cents: The tweeter driver itself is sealed, so changing the shape/volume shouldn't affect it at all. And for the mids, since the volume of the chamber is the same, I don't think there will be any issue. As long as the driver arrangement/spacing is the same and the baffle width isn't significantly changed, you should be fine.