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The Center of the Sun - photos


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#1 of 59 OFFLINE   Patrick Sun

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Posted February 21 2001 - 03:07 PM

Okay, here's a bunch of photo's of my DIY center channel speaker construction. I'm sure there are plenty of ways better to build the box, but going for simplicity and hope that form follows function.

The idea being I wanted a more consistent front sound stage, so I decided to use the tweeter and midrange from my DIY main speakers, and their crossover network. Then I would surround the tweeter and midrange with a woofer on either side of them. It's a modified D'Appolito design for center channel speakers.

This meant I had to figure out what woofer driver I would need to use to give my good coverage in the upper bass range as my midrange and tweeter handle the frequencies from around 460Hz and up. My main speakers had paper cones, so that was a consideration in the woofer driver selection.

With the help of EdP (can't thank him enough!) and many others on the HTT/HTF/HTG, I finally decided on the Vifa M18WO-09-08's, a paper coned driver. I had considered the Vifa P17WJ-00-08's, but it was a polyconed driver, and the M18WO-09-08 having a better low end response, I decided to go the paper cone route.

The components.
1 Philips AD11600/T8 1" dome tweeter
1 Peerless 1385 4" midrange (encapsulated)
2 Vifa M18WO-0908 woofer drivers.
2 2" wide ports 6.8" long - tuned enclosure to 45Hz
14 liters of volume for each woofer compartment
3/4" thick MDF to be veneered in something resembling rosewood.
28"x10"x14.3" are the outer dimensions for the enclosure.

Here we go:

Day 1 (Saturday 2/17/01)

The raw materials - wood panels:

Photo 1 : Here are the scraps of MDF from my previous Sunosub projects.

Photo 2 : More MDF scraps.

Photo 3 : Here a look of the MDF panel cut to my specifications by a friend of mine with a wood shop that would put Tim "The Tool Man" Taylor to shame.

Day 2 (Sunday 2/18/01)

Assembly

Photo 4 : For the front panel, I decide to use T-nuts so I can take out the drivers easily, this means glueing in a piece of plywood to give the T-nuts something to sink their teeth into because MDF is easily stripped. Here I am marking where the plywood panel should go on the backside of the front panel.

Photo 5 : I test for fit of the panel, roughly, and this give me an idea of how things will be put together.

Photo 6 : Here's the plywood panel and the glue.

Photo 7 : I proceed to squirt the glue on the back of the front panel.

Photo 8 : The plywood is glued in place.

Photo 9 : It doesn't look like it, but I'd got that front panel and the plywood underneath that stack of MDF, and this will apply the weight for a strong glue bond.

Photo 10 : Now I start placement of the tweeter and midrange, as well as the inner walls/braces for the enclosure.

Photo 11 : I mark off the walls and the drivers on the plywood for cutting purposes.

Photo 12 : Here's a close-up of the markings I made.

Photo 13 : Using a ruler and a compass, I draw the circles I need to cut into the front panel for the tweeter and midrange.

Photo 14 : I start with drilling the pilot hole for the router and the circle jig combo.

Photo 15 : The router doing its thing, cutting circles for me.

Photo 16 : Both the holes for the tweeter and midrange are now cut.

Photo 17 : I test for fit of the drivers.

Photo 18 : Next I start on the hole for the woofers. This gives me an idea of the total area the woofer will occupy on the front panel.

Photo 19 : I do the hole for the other woofer.

Photo 20 : After finding the center of the woofer hole and the inner width I need, I drill in a pilot hole for the router/jig combo.

Photo 21 : Routing out the woofer hole.

Photo 22 : Woofer hole finish and woofer waiting for placement.

Photo 23 : Test for fit of the woofer hole.

Photo 24 : I finish cutting out the hole for the other woofer.

Photo 25 : Test for fit of the other woofer hole.

Photo 26 : On the back panel, I mark the center point for the small terminal cup, this requires a 2" hole.

Photo 27 : While I drill out a pilot hole, I quickly discover my jig won't allow me to cut in a 2" hole.

Photo 28 : I use the compass to draw the circle, and then use the router free hand and cut out the cup hole.

Photo 29 : Test for fit of the terminal cup in the back panel.

Photo 30 : I drill holes for the screws to be used to firmly attach the cup to the back panel.

Photo 31 : I use 6-32 1.5" screws/nuts for the terminal cup.

Photo 32 : Screws are in.

Photo 33 : Nuts are screws on with washers.

Photo 34 : I drill the holes for the tweeter.

Photo 35 : I drill the holes for the midrange.

Photo 36 : To use T-nuts, the hole needs to be widen just a little bit, about 1/4" deep, which explains the masking tape on the drill bit.

Photo 37 : I apply a little glue around the holes for the T-nuts for extra adhesive.

Photo 38 : Then I hammer in the T-nuts.

Photo 39 : To seal the T-nuts, I apply some more glue around the T-nuts.

Photo 40 : I do the same for the midrange regarding T-nuts.

Photo 41 : I start on the woofer screw holes and the T-nuts, but then I realize I need to cut in the port holes...

Photo 42 : I place the ports for fit on the front panel.

Photo 43 : I draw in the port's outer ring and the hole needed for each port.

Photo 44 : I freehand the port with the router (since it doesn't have to be perfectly cut).

Photo 45 : Test for fit of the port and the new port hole.

Photo 46 : Both port holes have been cut.

Photo 47 : Test for fit of the ports.

Photo 48 : Next I start on the inside walls and the bracing for the back panel (which will allow me to use wood screws to screw in the back panel, and give me access later when I need to make changes for the crossover network.

Photo 49 : I use a saber saw to cut out of the corners out of the inner walls for the bracing to sit on.

Photo 50 : Test for fit of the bracing and the walls.

Photo 51 : Here's a shot of both inner walls with the required corners cut out of them.

Photo 52 : Here is where I draw in the grooves that I will use to hold piece of plywood that have the crossover network for the tweeter and midrange on one piece, and the bass network for the other piece.

Photo 53 : I use the router, and the straight piece of MDF to provide a rail to slide the router down to route in a 1/4" deep groove into the walls.

Photo 54 : The router in action, routing out the groove.

Photo 55 : One wall's grooves are done.

Photo 56 : The other wall's grooves are done, and the plywood pieces are tested for fit.

Photo 57 : This is how the crossover network will look inside the enclosure.

Day 3 (2/19/01)

Photo 58 : I finish applying glue for the rest of the mounting holes for the T-nuts.

Photo 59 : I hammer in the T-nuts for the woofer mounting holes.

Photo 60 : I seal up the T-nuts for the mounting holes.

Photo 61 : finally done with all the holes and T-nuts.

Photo 62 : Now is the time to glue the top, bottom, and side panel together.

Photo 63 : Apply the glue on the bottom panel.

Photo 64 : Apply the glue to the top panel.

Photo 65 : Apply the glue to the inside wall panels.

Photo 66 : I use the front panel (on the bottom) to line up the panels before clamping the panels together.

Photo 67 : The clamps are used to keep the panels glued together as tight and close to being a rectangular box as possible.

Photo 68 : One more look at the clamped up box. Notice the crossover panel stuck between the inner wall panel for fit.

Photo 69 : While the box is clamped, I was playing around with the bracing, and noticed that the bracing is sitting a bit too high, so I route just a little bit off the bracing so I can account for the weather-stripping later.

Photo 70 : Here's a look at the bracing.

Day 4 (2/20/01)

Photo 71 : This is the day I glue the front panel to the box, so here's all the necessary glue on the front panel.

Photo 72 : More clamp action, but this time, it's to clamp the front panel to the box.

That's it for now.

I'm waiting for some crossover parts, mainly the polypropylene capacitors from Madisound.

Next up:

1. Finish the crossover networks.

2. Install the bracing (leaving a 1/16" gap for the weather-stripping to add to the final back panel depth.

3. Veneer the box, cut out the driver holes in the veneer.

4. Screw in the drivers, hook them up the crossover, and hook up the crossover to the terminal cup.

5. Hook up the center channel speaker to the receiver and have a listen.

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#2 of 59 OFFLINE   David A. Frattaroli

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Posted February 22 2001 - 12:01 AM

Looks like it's coming along great, Patrick. You could probably cut your production time in half if you didn't stop to take pics every 60 seconds! Posted Image

Seriously though, you can never have enough pictures.
Keep 'em coming.

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#3 of 59 OFFLINE   Patrick Sun

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Posted February 22 2001 - 12:33 AM

David, people keep telling me that I would do the projects faster, but in the end, with waiting times and drying times, I doubt it. Plus, taking a photo break helps me plan out the next step and allows me time to think about it, instead of just plowing into oblivion.

If I get the right veneer, I will experiment, and try the procedure you described for applying the veneer for your DAF's, with the glue on both surfaces, dried, and then iron the veneer onto the MDF. I do appreciate that section on you HT DIY website.


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#4 of 59 OFFLINE   Philip Hamm

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Posted February 22 2001 - 12:41 AM

Thanks for taking so much time to share your experience with us, it is much appreciated. Keep this up and you might bring a new meaning to the term "Pat's the best".

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#5 of 59 OFFLINE   Patrick Sun

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Posted February 22 2001 - 01:40 AM

Phil, thanks for the kind words. I mainly just make it up as I go along, so don't take my journey as the only way to do something, there are plenty of ways to skin a cat, but at least people should get less intimidated by the idea of DIY after seeing the photos.

Believe me, the construction of the box is the easy part, I'll wager that the crossover network will drive me nutty in the coming weeks. That's the proof in the pudding.


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#6 of 59 OFFLINE   Anthony F.

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Posted February 22 2001 - 01:54 AM

Looks great so far! The bracing looks rather substantial. Is this pretty standard or is it a bit of DIY overkill. Just wondering how resonsances affect speakers that aren't designed to crack foundations. What the effect would be of less bracing, other than a lighter box. Posted Image

#7 of 59 OFFLINE   RAF

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Posted February 22 2001 - 03:00 AM

Patrick,

Very nicely documented!

Posted Image Posted Image

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#8 of 59 OFFLINE   Patrick Sun

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Posted February 22 2001 - 03:28 AM

Anthony, I'm using the back bracing just so I have some pine to screw and unscrew the wood screws into when I need to remove the back panel and gain access into the innards of the enclosure to make changes, mainly in the crossover section for dialing into the right mix of crossover components. MDF won't survive repeated screwings/unscrewings because it would be stripped too easily. It just adds some rigidity to the box, but probably not necessary (most commercial boxes probably don't have a lot of bracing in them). The little speakers are usually made with 1/2" thick MDF or wood or particle board (yuck!).

Resonance problems might occur but MDF is pretty dead (many speaker makers use it). It depends on the type of wood used, and how it interacts with the frequencies. Some do their best to use dead sounding wood, like marine-treated woods (I think GregM likes the baltic birch for building speaker cabinets, but my memory is fuzzy on the exact name of the type of wood, so I could have gotten that part wrong).

RAF, thanks! Just thought I'd share a different project with you all. With so many DIY subwoofers in here, it's good to shake up the mix. Posted Image


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#9 of 59 OFFLINE   Chris Hoppe

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Posted February 22 2001 - 06:53 AM

Pat, can I ask where you are getting the crossover design? Is this based on an existing kit or are you designing a crossover from scratch?
What you got back home, little sister to play your fuzzy warbles on?

#10 of 59 OFFLINE   Patrick Sun

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Posted February 22 2001 - 07:14 AM

Chris, I am using the same tweeter and midrange drivers that are in my DIY main speakers. Here's a webpage for the construction of them from my old EE professor, Dr. Leach of Ga. Tech.

Here's the crossover for this particular 3-way speaker.

So I will be using the crossover for the tweeter and midrange, and then doing the designing for the crossover for the woofers.

The tweeter (2nd order) crossover point is 4800Hz. Its L-pad is around -2dB.

The midrange crossover points are (2nd order) 460Hz and (1st order) 2400Hz. Its L-pad is around -3dB.

I plan to cross the woofers at around 400Hz with a 2nd order L-C circuit.

The problem was getting the same consistent sound across the front 3 speakers, so that's why I am using the same tweeter and midrange which take care of frequencies from 460Hz-20Khz. The woofer are only working from around 100Hz-450Hz.

So that's where I am. I have ordered the components for wiring the woofer in parallel and in series, but I think I'll be using the series connection for ease of design and for getting the SPLs of all the drivers aligned easier.


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#11 of 59 OFFLINE   Chris Hoppe

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Posted February 22 2001 - 08:16 AM

Another thing to consider Pat..

What your building there is not really an MTM, which is actually a good thing, as it's not good to place an MTM sideways.

The woofers do not need to be symetrically arranged because they are operating below the range where they would contribute much to the dispersion pattern.

/ T
W/ M

I think perhaps your best option is to use the same woofer as the original system you are trying to match. Only instead of placing it below the vertical mid and tweet, place it to one side. You can then rearrange the box dimensions however you want, as long as you maintain the same volume and tuning.

It's sound should be mostly indistinguishable from the mains.


What you got back home, little sister to play your fuzzy warbles on?

#12 of 59 OFFLINE   Ron-P

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Posted February 22 2001 - 08:40 AM

Looks awesome Pat Posted Image Posted Image I wish I had enough time to build speakers, but my next project is a two-story club house for my daughter. Maybe I'll put a surround system in it Posted Image

One suggestion though. From now on when you take your pictures have a nice looking brunette in a swimsuit model everything Posted Image


Peace Out~ Posted Image

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#13 of 59 OFFLINE   Patrick Sun

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Posted February 22 2001 - 09:05 AM

Chris, I thought about doing that (flipping the woofer to the side of the tweeter/midrange), but aesthetically, it didn't appeal to me, and the original woofer is 10" and my total height requirement was 10" including panel thickness, so I threw that design out the window. Plus, I hated the asymmetrical-ness of that design. I call mine a W-(T/M)-W form factor CC design (like the Aerial center channel).

Ric, thanks. Will this link do for you?


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#14 of 59 OFFLINE   Andres Munoz

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Posted February 23 2001 - 01:39 AM

Very nice Pat. You're the best at documenting progress. Lots of pics and detailed explanations.
Can't wait for the rest.

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#15 of 59 OFFLINE   Patrick Sun

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Posted February 24 2001 - 04:09 AM

Geez, I got in most of my capacitors from Madisound yesterday, so I totaly gEEked out last night and was laying out the crossover networks. I had forgotten what a pain that part of the process was. But in the end, I got to an acceptable compromise. I was planning on putting the tweeter and midrange crossover networks on one panel, and the woofer crossover network on the other panel, but in the end, I had to use one panel for the midrange, and I stuck the crossover networds for the tweeter and woofer on the other panel. It was time-consuming (for me) since I started from scratch with no pre-fab boards. I had the edited for TV version of Starship Troopers on, so passed part of the time pretty quickly.

I'll try to have some more pix up by Monday or Tuesday if not earlier.


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#16 of 59 OFFLINE   Patrick Sun

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Posted February 25 2001 - 10:53 AM

Well, folks, The Center of The Sun (COTS) is operational! I worked about 5-6 hours today to get it done. I finalized all the wiring of the crossover and the connections to all the drivers. I'm still waiting on the final version of a 20uF polypropylene capacitor, but I'm using 2 10uF electrolytic caps just to get the sucker working. Hopefully I'll get the final cap in the mail tomorrow via UPS. I made my ports, and installed them, as well as screwing in all the drivers (20 screws! Ack!) by hand (can never be too careful not to puncture a hole in the drivers).

Currently, I have it playing as the left front speakers, and I'm pretty darn impressed at how close it sounds to my right front speakers. It's eerie. It doesn't sounds like my current center channel speaker, which has always been a little boxy sounding to me.

I could run 2 of these COTS as mains and most people wouldn't be able to tell them apart from my other mains. In fact, it wouldn't take much to convert this design to tower speakers at all either.

I'm also surprised I got all my wiring and soldering done correctly on the first shot. Posted Image

I have the 2 woofer drivers hooked up in series, and used the crossover design for that particular configuration. It doesn't seem to have an adverse affect on the overall sound quality. I'll try to run some measurement of the 300-600Hz range to see if I have a dip there, but I'll do this later after I'm take a well deserves break for the rest of the day.

BTW, this COTS is truly a heavy beast! I'm going to have to install another wire shelf to help out in the weight department because I think my RPTV would not withstand so much weight on top of it well. I'm guessing it weighs around 30-45 pounds with all the drivers, crossover components, and MDF in it.

I'll try to have some photos up when I finalize the crossover with that 1 last capacitor.

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#17 of 59 OFFLINE   Patrick Sun

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Posted February 26 2001 - 03:56 PM

Day 5 (2/22/01)

Photo 73 : I test for fit on my bracing, and determine I need to sand down the inner walls just a bit, so that's why the sander is there.

Photo 74 : The long brace needed a bit routed off (like Lincoln logs), and I applied glue on the required surfaces.

Photo 75 : The glue is also applied to where the bracing will be attached. I use a pen to draw a pair of lines where the brace should be aligned.

Photo 76 : Clamps are placed to squeeze the bracing's glue for a tight bond.

Photo 77 : The cabinet is flipped over, and I apply glue for the other long bracing piece.

Photo 78 : Again, clamps are used to squeeze the bracing for a tight bond.

Photo 79 : More glue, more bracing, this time, it's the piece that goes along the side of the cabinet.

Photo 80 : Using the clamp, and the short piece, I position the side bracing between the 2 lines I previously drew for final placement (not shown). This is to ensure the fit of the "T" style bracing I'm using.

Photo 81 : I glue the other side bracing.

Photo 82 : This gives a better picture of the placement of the side brace (I also glue the bracing's bottom which butts into the inside front panel).

Photo 83 : Here's a shot of both bracings being clamped for a good couple of hours (or more). You can also see all the glue I apply to the inner walls and the long pieces of bracing. Go nuts with the glue!

Photo 84 : This is a close-up of the clamping and how the "T" style bracing is being utilized. At this point, I haven't glued that short piece of bracing yet.

Photo 85 : I just remembered to drill holes through each inner wall so I can feed the woofer drivers' wires to their terminals. As you can see it's a tight fit with the power drill. I recommend drilling the holes earlier than this, before installing them into the box.

Photo 86 : I test for proper hole size by feeding a piece of wire through the hole I just drilled, this is the second wall. I needed 2 passes to get the hole oblong enough to fit the speaker wire through it.

Photo 87 : Finally the top little piece of bracing is ready to be glued to the side bracing to form the "T".

Photo 88 : There's lots of surfaces to apply glue for these little short pieces of bracing.

Photo 89 : More clamping is involved in getting the tight bond from just glueing the bracing to the cabinet's inner walls.

Photo 90 : I quickly get both little pieces of bracing glued into place and clamped. I give the glue of the bracing the entire next day for the glue to dry.

Day 6 (2/23/01)

Photo 91 : It's now time to caulk the inner seams of the cabinet with all the bracing in place.

Photo 92 : As you can see, I've caulked the backside of the cabinet inner seams.

Photo 93 : Finally, all the inner seams are caulked.

I wait an hour for the caulk to dry. While it's drying, I start on the crossover network. This takes forever and a day to do. There's lots of places where you just have to be patient, and do all the little things to get it wired up correctly.

Photo 94 : I originally wanted to put my tweeter and midrange crossover components on 1 board, and the woofer on another board, but it just wasn't going to happen, I ran out of real estate on the board for both the tweeter and midrange, so I put the midrange on one board and the tweeter and woofer on the other board. This part took a while since I was playing around with the best way to lay everything out, so to get to this point, I must have spent 1-2 hour mucking around. There is one capacitor missing (I used an electrolytic cap in the upcoming photos just to get the crossover running while I waited for the polypropylene cap to arrive).

Photo 95 : I mark the holes for the terminals (black with screws on them) and drill them. I got the terminals and the other terminal mounts at Radio Shack.

Photo 96 : More drilling of holes for the components on this board. I do the same with the other board, of course.

Photo 97 : Here is what the boards look like with most every component tie-wrapped to the board. The terminals are attached with little machine screws and nuts (bought at Home Depot).

Photo 98 : Here's a shot of me screwing around...actually getting the components connected to one another based on the crossover I cobbled together. This board is the midrange crossover. It's always a good idea to keep your inductors oriented 90 degrees from one another.

Photo 99 : Just a shot of most of the bits and pieces I used, like male and female spade connectors, and the ring terminal connectors (I spent the next day getting all my inputs terminated with the ring connectors for a nice clean fit, it was a tedious, and yet, therapeutic exercise. I use the insulated female spade connectors when I knew it was going to be used to connect to a driver (to avoid shorting out the connection). The crimper is a godsend. Can't do good connections without it. At this point, it's around 3 a.m. and I'm tired, so I go to sleep.

Day 7 (2/25/01)

Had a wedding to go to on Saturday, and just didn't feel like working on this project, so I took the day off. Now's it's Sunday.

Photo 100 : Doesn't my cat look so impressed with me? I bring in the cabinet, and the drivers because it's time to put it all together!

Photo 101 : These are wires for the woofer drivers. For the connections to the crossover network, I crimp on the insulated female spade connectors to avoid short circuits (If you're cheap, just wrap them up with electrical tape, red for the positive lead, black for the negative lead). I always wrap the negative lead wire with black electrical tape to avoid confusion later. The female spades that will be connected to the woofer driver is not insulated because they will be a couple of inches apart when connected to the driver.

Photo 102 : A shot of me crimping these nifty ring terminal connectors. They allow be to really neaten up the crossover on the input terminals where I have make those little bitty jumpers for provide the positive and negative terminals for 3 sets of drivers (seen on the left side of the board). I had to solder 3 inductors in series to get 8 mH of inductance (FYI). And there's the electrolytic caps I am using temporarily until I get my poly cap (needed two 10 uF caps parallelled to get a 20uF cap) for the woofer crossover.

Photo 103 : Here's a close-up view of both crossover board slipped into their new home.

Photo 104 : Here's a wide view of the backside of the speaker with the crossover installed. I measured it just right to fit 2 levels of crossover components.

Photo 105 : I install the midrange driver, and then connect the wires for the tweeter. My other kitty is fascinated by the whole process.

Photo 106 : Next up is one of the woofer drivers, notice I don't need the insulated female spade connectors.

Photo 107 : Make sure you take your time screwing in the driver screws. I use my other hand to shield the head of the screwdriver from the cone, lest it slip and puncture it. This is where using T-nuts really pays off. I think I used 10-24 1.5" machine screws for the woofers and midrange. Again, kitty is mesmerized by the process.

Photo 108 : What can I say, kitty (Fred) just can't wait for me to finish up so I can play with him.

Photo 109 : The tweeter screws are 8-32 1.5" machine screws IIRC. I use the corresponding T-nuts for the tweeter driver.

Photo 110 : And here is the midrange. This is laborious since I dare not use a power drill.

Photo 111 : The other woofer's wires are connected to the driver.

Photo 112 : Finally, all the drivers have been screwed into all the front panel.

Photo 113 : Here's my testing which wood screw I want to use for attaching the back panel to the cabinet. This one is a #6 wood screw. I test for depth as well as "unscrewability" in case I need to get back inside the cabinet later.

Photo 114 : I test a #8 wood screw, and this is the one I decide to use. It was harder to strip its phillips head, so that was part of my rationale to use it over the #6 wood screw.

Photo 115 : I mark where the bracing is the strongest, so I can intersect some lines to get the screw hole placements in a moment.

Photo 116 : Just thought that it was really tough to get the back panel off if I can't push a hammer through the woofer hole (which I had been doing before I screwed in all the drivers to the front panel). I drill 2 holes, and loop some speaker wire through the holes (with 2 knots for added strength/support when I pull on it later).

Photo 117 : This is what the back panel will have hanging out of it for the interim (I'm thinking about putting in a "handle" later). But it works, and you never see it once I put it in its place in the HT.

Photo 118 : I connect the crossover leads to the terminal leads of the back panel. I use a long piece of speaker wire for flexibility when I take off the back panel and don't want to disconnect it from the crossover.

Photo 119 : This is foam weatherstripping which I'll apply the bracing to produce a good seal mainly for the woofer enclosures.

Photo 120 : I apply the weatherstripping all around the bracing. Yes, I forget to put it on the inner walls, but I'll be back inside once I finalize my woofer crossover components, so I'll fix that at a later time.

Photo 121 : It's finally time to close up the cabinet.

Photo 122 : Remember those marks I made? Now I use them to make the intersections which give me the holes to drill for the wood screws.

Photo 123 : I use an 1/8" bit to make the pilot holes for the wood screws.

Photo 124 : To countersink the wood screws, I use a thicker bit to drill a depth of 1/8" or so. The masking tape is used for the depth marker.

Photo 125 : The screws are screwed into the bracing nice and evenly. I confess, I forgot to include additional depth for the foam weatherstripping, so the back panel is not completely flush with the rest of the cabinet. I will remedy this by routing out a perimeter 1/16" deep, 1.75" wide, on the inside back panel. I got the medium compressible weatherstripping. Doh!

Photo 126 : The last thing to do is create the ports for each woofer. I need roughly 7" long ports 2" wide. I found these 2" wide, 4" long ports, so I bought 4 of them with the intention of sawing off 2 of the ports to use to extend the other 2 ports. I love my PVC pipe saw, just handy for this application. I wound up having to saw it off around to get the 3" of length for each pipe add-on.

Photo 127 : Both of the chopped down ports. They get chopped down where their fins disappear.

Photo 128 : I use black electrical tape for the adhesive on the inside and outside of the port.

Photo 129 : Here's the total new length for the port.

Photo 130 : Ta-da! Once the ports have been inserted and hammered into the port holes, the center channel speakers is finally operational.

Photo 131 : Here's a shot from the left corner.

Photo 132 : And here's a shot from the right corner (sorry, proud papa operating the camera!)

Photo 133 : Since I can't connect the CC speaker up to my current setup (have to re-arrange everything to fit this speaker over the RPTV), so just for fun, I listened to it as the left speaker just to see if I had gotten my connection all wired up correctly. Amazingly enough, I got my crossover hooked up right on the 1st try. Oh yeah, next to it is my Giant Pickle Sub.

Photo 134 : A gag shot of the CC speaker incorporated into the HT setup.

Photo 135 : Here's what my HT setup looked like before I moved everything around to accomodate this new CC speaker.

Photo 136 : This is how my HT setup looks after I moved my HT gear around. I had to relegate my Harman Kardon PA5800 5-channel amp into the closet behind the subwoofer where my subwoofer amp also resides (but that's okay, I rarely need to "see" it anyway).

Photo 137 : Here is how my current HT looks like with the new CC speaker in place. I'm tempted to forego the veneering as the front panel's color is a close match with my mains, and it's not like I'm impressing anyone with my stuff anyway.

Day 8 (2/26/01)

Well, I have just a bit of testing to do to finalize my woofer driver crossover. I did some measurements of the CC speaker with the woofers connected in series. I'll post the graph as soon as I can get the numbers all graphed out.

But, from a cursory glance at the numbers, I can tell that I will need to connect the drivers in parallel to get a 4-6dB increase in the SPL output from 400Hz and down to even out the output from the rest of the drivers.

I calibrated my new CC speaker with the rest of my system, and I needed to bumped up the center channel speaker output by +2dBs on my receiver. I'm thinking when I go with a paralleled woofer load, I won't have to boost the center channel output much at all.

Stay tuned for the rest of the story.

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PatCave ; HT Pix ; Gear ; Sunosub I + III ; DVDs ; LDs
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#18 of 59 OFFLINE   Greg Monfort

Greg Monfort

    Supporting Actor



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Posted February 26 2001 - 04:51 PM

Lookin' good Pat! Posted Image Well braced, I like that. Over the top documentation too. Posted Image Makes me wish I had done the same over the years.
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>But, from a cursory glance at the numbers, I can tell that I will need to connect the drivers in parallel to get a 4-6dB increase in the SPL output from 400Hz and down to even out the output from the rest of the drivers.

>I calibrated my new CC speaker with the rest of my system, and I needed to bumped up the center channel speaker output by +2dBs on my receiver. I'm thinking when I go with a paralleled woofer load, I won't have to boost the center channel output much at all.
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You lost me. I thought from all the correspondence that you had worked it to have matching efficiencies WRT the mains. With the TV being a baffle, seems it would be close to the floor gain of the mains. If tonal balance is close, it may be better to raise the mains up off the floor more.

GM

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Loud is beautiful, if it's clean
Loud Is Beautiful, If It's Clean

#19 of 59 OFFLINE   David A. Frattaroli

David A. Frattaroli

    Stunt Coordinator



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Posted February 26 2001 - 11:49 PM

Nice Job.
Pat, you could use some CA glue to connect those port lengths. It would form a permanent bond since it fuses to the plastic together. You can get CA glue at hobby/model shops.

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#20 of 59 OFFLINE   Patrick Sun

Patrick Sun

    Studio Mogul



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Posted February 27 2001 - 03:18 AM

Dave, thanks for the tip. If the electrical tape doesn't hold, I'll give the CA glue a shot.

GregM, take a gander below if you'd like:

Here's a graph of the CC's frequency response with the woofers connected in series.

I can't really explain the dip near 100Hz. If I wanted to keep the woofer in series configuration, I am thinking about either taming the tweeter with a different set of current divider resistors. But I think the better thing to do (to make up for the 1/2 space baffle of the CC) is to change the midrange current divider to mimic the tweeter's current divider to gain some more dBs from 450Hz-5000Hz. But this would leave me with a little less SPL on the woofer end relative to the midrange/tweeter. But, depending on how much I gain when I parallel the woofer, I'll see how much I want to change the L-pads on the tweeter and midrange crossover.


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PatCave ; HT Pix ; Gear ; Sunosub I + III ; DVDs ; LDs
"Jee-sus, it's like Iwo Jima out there" - Roger Sterling on "Mad Men"
Patcave | 2006 Films | 2007 Films | Flickr | Comic-Con 2012 | Dragon*Con 2012