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17
Speaker Building
Conclusion
7
Connecting the Cabinets
5
The pieces that connect the upper open back units and lower bass
cabinets are constructed of 18 gauge perforated metal. I used an
online truncated cone calculator to get the pattern I needed for cutting
the metal to the correct size. I then hand formed it into the cone shape
and TIG welded it together, cutting a piece of circular metal that fit into
the top, welded that, and then drilled a hole to facilitate a way to bolt
the perforated cone to the upper MTM assembly.
Before everything bolted together, I cut a circular piece of wood
to mount the RCA jacks. This connects the wiring from the lower
woofer module (that houses the crossover) to the upper MTM
module, allowing the two to be separated. It was hot glued into
place right below the metal piece that bolts the perforated cone to
the MTM unit. I sewed up a grill cloth cover for the perforated metal,
using the same pattern I used to make that truncated cone.
Finishing Touches
6
This was then wrapped in speaker carpet and upholstered in vinyl
and faux suede, using a sewing machine (which was a first for me).
My wife gave me some pointers, ran a couple stitches, and then I
jumped in and started sewing up a fury! Luckily for me it all worked
out on the first try. I took the covers to a shop to have the “RSR” logo
embroidered onto them. I then stitched up the back and pulled them
over the enclosures, securing it with spray glue and staples. Roxul
brand rock wool was used for interior damping.
I’d also like to note the re-anodizing of the phase plugs on the
RS180 drivers. I watched a few videos on YouTube to see how it’s
done, and gave it a try. It took me about four attempts to get them
right. If you’d like to try it, the phase plugs popped right out for me
using a punch and a hammer from the backside of the speaker.
Acetone on a Q-tip dissolves the glue on the pole piece and phase
plug. I also watched a video on removing the anodizing. This uses
common drain unclogging crystals, also known as caustic soda.
After the stripping process, I used some 400 grit wet/dry sand paper
to hand sand them, then my bench grinder with a polishing wheel to
shine up the plug before the anodizing process.
Last, I used intake valves out of a cylinder head I had on hand to
use as feet. These were removed and polished up on my drill press.
That pretty much sums up the build of this speaker, which took
probably the better part of a year’s worth of work.
After all was completed I had a couple bum tweeters. They were finished literally three days before the Midwest Audiofest. I had one day to get a
quick listen and realize the tweeters were no good. I installed a set of Usher 9950s to verify everything else was working. The next day, we had
a storm come through and take out my power. Friday came, and off to the show I went with intentions of buying a new set of RS28F tweeters to
install the day of the show.
I ended up replacing them with another set I purchased at the 2013 tent sale. This time it was a score! I didn’t have time to do much final
tweaking before the show, and this was made apparent by the tweeters being a bit too “hot”. When I returned from the show I was able to adjust
the level and tune the bass enclosures a little. Overall, these are complete successes. They sound great and look the part, too.
About the Designer: Eric Woodring
I’ve been building speakers since I was probably 15-16 years old (now 38, how time flies!!) I started out in the
automotive side doing installs for friends and building a few home speakers here and there. I didn’t really get into
it heavily till about 10-12 years ago. It’s still fun to learn new things in the sound domain as well as my construction
skills. It’s great to have a place like Parts Express (who I’ve been ordering from since I was 15-16 years old...) to
support DIYers of all types. Not only selling the parts, but their customer support, hosting the MWAF/tent sale, and
the TechTalk board where I’ve been able to connect with fellow DIYers is about as good as it gets.
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