The #1 Internet Source Of Audio, Video and Speaker Building     Components, For Home, Office, Mobile And Prosound.       Call: 800-338-0531 Site Last Updated   The SO1: A Solid Beginner Project I struggled to arrive at a name for my version of the Dayton 2 (Wayne at speakerbuilder.net) or BR-1 (Paul at PE), both built using the Dayton 6 ½" woofer and 1 1/8" silk dome tweeter.  As I pondered, my 14 year old son jibed "How about Stupid Obsession?" I would never show disrespect for anyone who builds speakers as a hobby, but the name appealed to my twisted sense of humor and reminded me that I should not take this hobby too seriously (see THE OBJECTIVE below).  Besides, the folks on Tech Talk usually have a good sense of humor, so I thought they might appreciate the name. Thus was born the SO1s.

The Objective

My objective, nothing nearly as technically elegant as stated by others on the Project Showcase, was to build a set of speakers as a form of relaxation over the 2000 Christmas vacation, using the drivers mentioned.  This objective resulted from a “stress reduction” tape I listened to for “continuing legal education” credit (required in California).  The presenter asserted that those who spend most of their lives behind a desk should have a hobby that requires them to use their hands and take more than a day to do a project.  That really "resonated" with me, to use the current parlance.  I had some old 6" x 8" Ford full range speakers left over after installing a new car stereo and speakers in my Mercury Villager minivan, and decided to build some speakers for my son's room.  So off I went surfing in search of tweeters, ran across the PE site, began reading posts on Tech Talk, was impressed with the community, and decided I would not only build speakers for my son, but also try a pair for myself using the aforementioned drivers.  Knowing nothing about crossover design, I originally planned just to use the stock Dayton 2000 Hz crossover, since that crossover point was a little over twice the posted Fs.

Then work intervened, requiring me to give up my Christmas vacation for an emergency hearing. I did not get to these speakers until May 2001. Good thing, too, because it gave me time to build other sets of beginner speakers and hone my woodworking skills a bit, as well as to learn more about crossovers and so forth from The Reverend (Wayne at speakerbuilder.net), Mr. Smartypants (aka PE Paul), and others on Tech Talk.

The objective was met.  I had fun building the SO1s and am pleased both with the sound and appearance. More on the sound is below under Impressions.

The Enclosure

I also had to arrive at a visual design.  At the time I was building these, I was toying with a different colored front baffle than the rest of the box.  I had seen some speakers on a website somewhere with a narrow grille (grille of course required for SAF) and thought I would like the look with a contrasting front baffle.  This required some space to either side of the drivers, that is, a design counter to the currently popular narrow-fronted speaker.  I also wanted the grilles to be even with the top and bottom of the speakers.  And I had to find someplace for the port.  I understood then (and I now understand I may have been wrong) that the port should not be close to the woofer, so I put it above the tweeter, creating an inverted pyramid shape. 

Center-to-center from the woofer to the tweeter is 5 3/4".  I did not measure CTC for the tweeter to port, but because of space constraint, placed the port very close to the tweeter.  The hole diameters were as follows: woofer - 6 9/16" outer, 5 13/16" inner, router depth for flush mounting 3/8"; tweeter - 4 7/16" outer, 3 13/16" inner, router depth for flush mounting 3/16"; port - 3 outer, 2 9/16" inner, router depth for flush mounting 3/32".  I routered the holes in the front baffle using my Sears 1.5 hp router and a Jasper circle jig (both newly acquired for this hobby).  I also routered the side edges only of the front baffle with a ½" roundover bit before construction.

I also constructed two H-braces, one for each box, out of scrap ½" MDF for the sides of the H, and 3/4" MDF for the cross brace, gluing with TiteBond II and clamping.  They were from scrap and I forgot to take notes about them, so I don't have dimensions, except I know the cross brace was 8" long, and around 3" wide.  Below I will discuss the crossover and modifications to it.  During box construction, I cut the hole for the speaker terminal cup with a jig saw, centering the hole on the back baffle, and predrilled the holes on the inside of the back baffle for installation of the crossover and add-on Zobel network, and on the outside for the terminal cup.  I also screwed the crossover, Zobel, and terminal cup in at that time, then removed them again, so I would not have to "break in" the MDF later. I always install the crossover after all painting, so that the crossover does not get covered in sanding dust.  I use hex heads because they are easier to install using my 1/4 inch ratchet inside the box after the box has been entirely assembled.  I use 3/4" black oxide screws from PE (see parts list) for external connections (drivers and terminal cup).

 Then I glued it all together, doing the back, top, bottom and sides at first.  On all sides but the front, I used liberal amounts of TiteBond II, and then clamped the box.  I also installed the H-braces using TiteBond II, locating them about 1/3 of the way down from the top, centered on the sides.  I used no screws.  (Picture shows the box assembled, with H-brace in place, but without front baffle.)  After the glue set, I sprayed flat black spray paint on the brace and above it so no raw MDF would be visible through the port after assembly.  Then I siliconed all the glued seams.  For the front baffle, I put a bead of silicone along the inner edges and TiteBond II along the outer edges, and clamped the baffle in place.  I did that because I used a round tube of silicone in a trigger applicator, and I knew it would be hard (more likely impossible) to get it inside after the box was glued up completely, especially with the H-brace in the way.  The boxes seem to have sealed fine.

At this time I also constructed the grilles, which I discuss separately below, and predrilled the pilot holes for the grille guides, and the holes in the grilles and cabinet for the insert and cup portions of the grill guides.  (Two pictures above, the completely assembled boxes are shown).  There is blue paint around one of the port holes because I had decided to paint the boxes blue to match a quilt in our bedroom, and thought I would need to install the ports before painting, so I "cut in" the port hole on one enclosure.  Good thing; the blue was all wrong and abandoned in favor of piano black.  I also decided I could wait until the end to glue in the ports, so I did no more cutting in.  Also notice the notches in the tweeter holes for the tweeter terminals.)

 The Crossover

As I write this, I have yet to build my own crossover.  I had ordered the stock Dayton 2000 Hz crossover when I first started on this project.  As time went by, I learned about Zobel filters and posted a question about whether I should use one.  PE Paul resoundingly responded “Yes” and gave me values, including a bypass cap.  I had no need to place a PE order at the time, so off I went to Fry’s to buy the parts (see parts list).  I never could find a .1 uF bypass cap anywhere, even later when I had reason to order from PE – that cap was backordered at the time.  So, my Zobel is a simple cap + resistor unit.  I soldered the cap and resistor together, Gooped them to a piece of Masonite the measurements for which did not keep, but around 1 inch wide and as long as the long side of the Dayton crossover.  Those were soldered to positive and negative lead wires, one end to go to the crossover and the other end to go to the woofer.

 Grille Construction 

I wanted a grille which was both narrow on the face of the enclosure and thin in width.  In my first two projects, using the Ford 6x8 speakers, I made grilles by cutting out pieces of ½" MDF with a jigsaw, but I am notoriously cheap and hated the waste.  So the next time (a center channel) I cut strips of 3/4" MDF and glued and clamped them to make the grill.  I intended to use a similar construction here.  Since I wanted the grille thin, at first I tried to use Masonite, but it would not glue together well.

So, I went back to ½" MDF.  For each grille, I cut two ½" strips to length for the tall side, and two strips about 1 1/4" wide for the top and bottom, less an inch in length to take account of the sides that I had already cut.  I then notched the top and bottom pieces at an angle to make room for the grille guides, and glued them together with TiteBond II and clamped them.  When they were dry, I ran them through the table saw with the blade as close as possible to the rip fence, which yielded a width just a little less thick than the length of the grill guide insert press fit pieces.  I think the width was a little less than 3/8".  Then I routered the front edges carefully with a ½" roundover bit, with the router mounted to a small tabletop router table.  Next I clamped them to the enclosures (which were not yet painted) and drilled guide holes with a small bit from the outside of the grilles into the enclosure, so that the grille guide inserts and cups would line up exactly when all work was done.  Then I drilled 3/8" inch holes for the grill guide inserts (which were sanded down a little to cut down on length), and painted the front and edges flat black, so the MDF would not show through the black grille cloth.

Result?  Not so great.  Three-eighths of an inch is not big enough around for the grille guide inserts, and I did not have access to a 7/16" bit, which is what is really required.  When I tried to press the grill guides in, the grilles came apart at the seams, but luckily suffered no damage.  So, I reglued and reclamped, borrowed a ½" auger drill bit from a neighbor, and, after the glue dried, redrilled the holes.  The holes were then too big for the guides to press fit, so I glued the guides in with Goop and let it dry for a while, then repainted the grilles with semi-gloss black (just because that was handy from a previous project) and let them dry overnight.

I was doing this last bit of work after I had finished painting the enclosures, so now it was time to stretch and staple PE’s black grill cloth over the grilles.  This is harder to do with the guides in place, but I knew had to glue the guides in and did want to risk glue dripping onto the cloth from the grille guide hole.  My wife, who is a quilter, used a rotary cutter to cut the cloth for me.  She also helped me hold the cloth in place and suggested I attach opposite corners, then the sides, while stretching the cloth.  I stapled the cloth in place as I was stretching it, then trimmed the excess cloth.

 

Finishing the Enclosures: The Elusive Black Piano Look I have learned that no matter how hard I try when I cut the pieces for an enclosure, nothing ever lines up perfectly.  It may be my table saw, which is quite old, or it may be me, or it may just be the way things are.  I always need to sand some edges and fill some imperfections.  I sand with a $15 Rock Solid 1/3 sheet sander from Orchard Super Hardware.  I slap on 60 grit sandpaper and in no time demolish those pesky places where the edges don’t line up.  I have found that spackle works best for filling cracks and holes, though I don’t use screws anymore.  Wood putty shrinks too much, takes too long to dry, and requires too many applications to get things right. So I did all that, and then began finish sanding.  Wayne J. posted some shots of piano black bases he made for a project, and I posted asking how he did it.  Following his instructions (which he adapted from Mike Rootz, whose project is also on Project Showcase), using my little Rock Solid sander, I sanded progressively with 80, 120, 320, and 400 grit sandpaper, leaving the MDF nice and smooth.

Then I tried to brush on some Zinsser sealer we had leftover from a bathroom refinishing project.  Disaster; too many brush strokes.  Off that came with the sander, and more progressive sanding til smooth again.  Then I sprayed both boxes with six coats of Zinsser BIN white pigmented shellac sealer, which you can buy in spray cans at OSH or Home Depot.  To make it easier to paint all six sides, I screwed four 1" screws about halfway in on the back where the terminal cup was to be installed.  I sprayed the back first, then turned each box over and propped those screws on a piece of scrap 3/4" MDF, and painted the other five sides.

I put the first coat on very thin, let it dry for probably half an hour, then put on a second coat.  I hand sanded between the 2d, 3d, 4th, and 5th coats with 400 grit sandpaper, leaving about half an hour between coats, then applied the final coat.

On a Friday night, I sanded the other five sides, tacked everything, and masked the backs with masking tape and newspaper.  I turned the boxes over on the screw bases discussed above, and began priming.  I put on grey Rustoleum automobile primer because Lowe’s, which is the only place I could find the Krylon High Gloss Black Appliance Epoxy recommended by Wayne J., did not have the epoxy primer he also recommended.  I applied four coats of the primer, again putting the first coat on thinly, and sanding between the 2d and 3d coats with 400 grit sandpaper and tacking before starting each new coat.  Friday night was done. 

On Saturday morning, I began the process of putting on six coats of the Krylon epoxy paint.  Again, the first coat went on very thin.  I waited about half an hour, then put on a second coat.  I then waited 2 hours and hand sanded with 400 grit paper.  I tacked and painted.  Then I waited 2 hours again and rubbed the surface with the 3M synthetic steel wool pads from the parts list, grade 000.  They work great for this purpose, better in my opinion than sandpaper.  I tacked and painted.  I repeated that every two hour until I reached six coats. 

Two hours after the final coat, I began applying Painter’s Touch clear gloss enamel.  I waited fifteen minutes to half an hour between coats.  I did no sanding or rubbing between coats.  The last couple of coats, I sprayed the front baffle, then the other sides, then put another coat on the front baffle, since it would not run like I was afraid the sides would.  I think that is part of why the front shines so well. 

I went to bed Saturday night feeling quite self-satisfied.  On Sunday morning I got up early, in a self-congratulatory mood, intending to take some pictures before church.  Pride goeth before the fall.  As I was moving the speakers into position for the shots, I banged a corner of one smack onto the front of another, digging all the way through to the white sealer on the front, but not really damaging the other box.  So I hand sanded using 220 grit until my mistake was feathered out.  I then used the 3M pad on the rest of the box.  Darned if I was going to prime again, so I just applied more Krylon epoxy – one coat before leaving for church, and another two after that, if I recall, again rubbing with the 3M pad and tacking between coats.  Then I put on three coats of the clear enamel, again putting it on thick on the front, until I ran out.  I called that good and let the boxes dry for a couple of days.

 Impressions

Initially, oh “bleep”!  Later, whoopee!  I will elaborate. For the initial tests, I used only foam in the cabinets and taped the port in place using duct tape.  I tested the speakers in our family room, which is 18 feet wide by 23 feet long, with lots of open area.  I put them on top of my 26 year old Frazier VIIs, which placed the tweeters very near to ear height while the listener is seated.  The speakers fire into the long part of the room.

Boo hoo.  Harsh highs, and weak bass.  I won’t bore you with my test music; it all sounded awful.  “Clearly all this DIY stuff has been a fraud and I am going to go eat worms.” So I cobbled together two tweeter pads with two pieces of wire, a resistor and twist connectors, connected that contraption to the crossover and positive tweeter lead, and put about 50% poly fill behind the woofer.  Listened again.  Much better.  It is amazing what magic a resistor and some poly fill can do.  Dire Straits “Brothers in Arms”, Boz Scaggs’ “Lowdown” and “Lido Shuffle”, Boston’s “More Than a Feeling”, and Dan Fogelberg’s “Higher Ground” all sounded much better, though I was still a little disappointed in the bass while very happy with the vocals and highs.

So I went ahead and finished the whole shebang.  As noted, in final assembly, I increased the poly fill behind the woofer.  Then, around 11:30 the night I finished them, I ran through the same songs plus some others.  Happier still.  Highs crisp and clear but not harsh; vocals clear and not sibilant; bass stronger, but I have to say, still weaker than I had thought it would be based on what had been said about these woofers on Tech Talk.

Then I finished the grilles and took the speakers upstairs to our bedroom, which is where they were intended to reside.  The bedroom is about 14 by 14, with a lot of furniture, including a tall queen size double padded bed.

What a difference a room makes!  I now understand all the debate over designing to a room.  In the bedroom with the speakers closer together and all the other stuff in the room, the SO1s sound phenomenal.  The bass is deep, tight, hard hitting, but not boomy.  The soundstage is no particular place, but sort of wanders around in front of you.  All the reference songs previously mentioned, plus “Thunder Road” and “Jungle Land” by the Boss, “Black Diamond” by the Rippingtons, and “Hotel California” by the Eagles sound great.  When Don Henley hits the bass drum twice after the opening bars of Hotel California, you can hear and feel the “thump thump.”  A guilty pleasure from my early years is “Pleasant Valley Sunday” by the Monkees, which gains a new clarity on the SO1s.  Chip Douglas’ great bass line and Michael Nesmith’s guitar hooks really stand out, and Micky Dolenz’ vocal is crisp without a hint of harshness or sibilance.

All in all, I am very pleased, especially since this is my first “real” project.  I would join those who say that these woofers and tweeters are an incredible bargain.  If you are a first timer and scared of building a crossover, I would use the Dayton crossover and add a Zobel and padding resistor.  You can make those additions without a soldering iron using twist-on connectors if you need to (though you can buy a soldering iron for about twice what you will pay for a package of twist-ons, so why not make the investment?)  If you are not put off by building a crossover, I would try Wayne’s Dayton 2 or Paul’s BR-1.

Acknowledgements

I know it’s not Oscar night, but I have to thank PE Paul, Wayne Jaeschke, Viperoni, and other folks whose names I neglected to record who posted responses to questions; Parts Express for selling good stuff at reasonable prices and for hosting such a great message board; my dad for the table saw; my wife for helping with the grilles (as well as all the other obvious mushy stuff); and my son for helping with the name.

Now go build some speakers!

Profile

Dan Carroll is an attorney who is nearing 50 but knows he is not 14 years older than he was when his son was born, nor 6 years older than when his daughter joined the family through international adoption, and certainly not 16 years older than the day he took his wedding vows.  He specializes in energy issues, which means you can blame him for the energy mess in California if you wish – he sure should not be running an old table saw and a new router putting load on the system in present circumstances!  He lives with his family and a golden retriever/chow/spaniel mix named Beauregard Emanuel Carroll in a small suburb of California’s fair capitol city.  When he is not working, spending time with his family, reading Tech Talk and speakerbuilder.net, working, building speakers and listening to music on them, working, watching his son’s Dixieland jazz band perform, eating too much, or working, he sleeps.

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