microTower: Removable Base Mod

[cogitech]

First, I'd like to take the opportunity to thank everyone who has contributed to the success of my first DIY loudspeaker project. From helping me decide which project is right for me and my room, to the designer(s) of the cabinets (Dave and Chris?) and the drivers (Mark), the supplier of the kit (Bob/CSS) and then all the help offered throughout the build process (so many who have offered help). A BIG thank you to all. This is a fantastic forum and I feel privileged to be able to "rub shoulders" with all of you folks.

But a community is about give and take, so I thought I would share something that I designed into my "Castle" microTower build.

Based on the recommendations of you good folks (Chris, specifically, I think) I had decided to make the bottom panel of my towers removeable. I had also decided to install a flat base under the "feet" of my tower because I am using them on carpet. The challenges with this configuration are:

1) Getting a perfect seal between the ported bottom panel and the inside perimeter cleats.

2) Fastening the ported bottom panel

3) Fastening the base plate

4) Configuring all of the above to be easy/convenient to remove for stuffing adjustment, etc.

It came to me in my sleep. Seriously, I woke up one night with this idea in my head.

Here are the steps for a simple, effective, perfectly sealed ported bottom panel and base plate:

1) Install 1/8" closed-cell foam-rubber weatherstripping around the entire perimeter of the cleats

2) Partially install 1\5/8" drywall screws in the extreme exterior corners of the ported bottom panel (pilot holes required!)

3) Position the ported bottom panel on top of the weatherstripped cleats and adjust the drywall screws to protrude between 1/16th and 1/8th of an inch past the tower "feet"

4) Align the base plate and pre-drill appropriate pilot holes for easy (but secure) installation of wood screws.

5) Remove base plate and re-drill (enlarge) the holes so the wood screws just barely slide through

6) Position the base plate and install the screws through the base plate and into the pilot holes in the "feet", using a progressive criss-cross pattern to bring the pressure of the base plate against the heads of the drywall screws, simultaneously compressing the ported bottom panel against the foam-rubber and sealing the enclosure

Note: To disassemble, simply remove 4 screws.

(Oh, and the drywall screws are not visible from normal viewing angles when the speaker is standing upright)

The attached photos should go a long way to illustrating this easy, effective mod.

[cogitech]

The speakers have been burning in for about 80 hours now and they sound fantastic (with some EQ). I still have to cut and install the 1/4" front and top baffles to make the drivers flush, and then stain/finish the cabinets, but I am not so motivated to do so anymore, now that I hear them.

BTW, I put the PSBs (behind in the first photo) and my subwoofer back down in the basement HT setup today. This microTowers are all I need on my 2-channel system

First photo is just before installing the drivers for the first time, second photo is the speakers in action...

[Nanook]

Looks great. Yes, the problem with listening to any project (particularly if it is a very successful one), is that you don't always "have the time" between listening sessions to put some sort of finish on them

I have a few speakers in the "raw" state that have never been finished.

[rvsixer]

Nice job.

[zman01]

Cogitech,

Good design with the removable base with cleats. You have used wood screws - which yields a pretty durable thread for ply wood. However, even better is using threaded inserts - that way you can screw and unscrew many times without fear of the thread wearing out.

And if you get the stuffing amount right quickly, then no worries on wearing the threads out anyways.

The sound will be even better with flush mouting the drivers - if possible please do that.

Your speakers look great by the way! Congrats on a succesful build.

-Zia

[cogitech]

Originally Posted by Nanook

Looks great. Yes, the problem with listening to any project (particularly if it is a very successful one), is that you don't always "have the time" between listening sessions to put some sort of finish on them

I have a few speakers in the "raw" state that have never been finished.

Thanks, Stew. My folks arrive from Ontario today and I thought I might get my father to work with me on finishing them over the Thanksgiving weekend. He likes to have something to do, and he always "does it right" If all goes well, I'll post some more photos next week.

[cogitech]

Originally Posted by rvsixer

Nice job.

Cheers!

[cogitech]

Originally Posted by zman01

Cogitech,

Good design with the removable base with cleats. You have used wood screws - which yields a pretty durable thread for ply wood. However, even better is using threaded inserts - that way you can screw and unscrew many times without fear of the thread wearing out.

And if you get the stuffing amount right quickly, then no worries on wearing the threads out anyways.

The sound will be even better with flush mouting the drivers - if possible please do that.

Your speakers look great by the way! Congrats on a succesful build.

-Zia

Thank you, Zia!

The potential issue with wood screws occured to me, so I chose screws with coarse threads and in the back of my mind I was thinking that I could always move to a larger calibre screw if I really needed to. The threaded inserts would be a much more refined approach, indeed. However, as you say, there may be very little need to remove the screws repeatedly. In fact, I got so lucky with my stuffing that I have only removed the screws once; to take the photos for this thread. The speakers sound fantasic as they are, so I am leaving well enough alone. Still, I am glad I invested the time and effort to making the bottom panel removable.

I do plan to flush mount the drivers by laminating 1/4" plywood baffles over the areas where the drivers are installed. The reason this has not been completed yet is because I was searching for a way to cut a perfect 4\7/8" hole in the 1/4" plywood. I finally found a hole cutting accessory for my Dremel, so it is just a matter of taking the time to do it. The wood type, grain, and finish will be different than that of the main tower. I plan to stain the main towers quite dark (but still showing the grain) and the 1/4" baffles in more of a honey/almond colour. I'll post pics when they are complete.

[von.ah]

Originally Posted by cogitech

I plan to stain the main towers quite dark (but still showing the grain) and the 1/4" baffles in more of a honey/almond colour. I'll post pics when they are complete.

That sounds sharp.
Great build. The MicroTower Castle Brigade gains another proud knight.
I've been listening to mine for months and have yet to finish the grilles.

[cogitech]

Originally Posted by von.ah

That sounds sharp.
Great build. The MicroTower Castle Brigade gains another proud knight.
I've been listening to mine for months and have yet to finish the grilles.

Thank you! I didn't realize there are more Castle builders out there. Yours look gorgeous as far as I can tell from your avatar!