I've purchased a set of Bob Brines TB-20 plans and have started the build...first few pictures. I was able to skimp on the materials and get 2 complete speakers out of one MDF sheet but listen to Bob's advice and get 1 and half at least so you can cut oversize. I was lucky and didn't make too many mistakes cutting or gluing and didn't need more than one 49 x 97 in sheet. Crosscut sled makes perfect 90s and is vital if you're going to try to use only one sheet.
More Pics
Here is the next set of pics...I have the small Jasper jig but made my own for the larger circle cuts. Jig is a straight board about 3/4" x 1 1/2" by 18 with a hole drilled in the middle to allow the 1/4" upcut straight bit to clear the jig then trial and error (some measurement too
) to drill a 1/4" hole in the jig the correct distance from the bit to pivot the router around and end up with a circle the correct size. (Note numerous holes for different size holes)
Bessey clamps really help on getting square glue ups on panels with no room to spare...even then it was a close run endeavor.
Last pic is the start of the supra baffles. I did make a mistake with the circle jig on one of the port openings but had enough scrap MDF to make a new one
Here is the next set of pics...I have the small Jasper jig but made my own for the larger circle cuts. Jig is a straight board about 3/4" x 1 1/2" by 18 with a hole drilled in the middle to allow the 1/4" upcut straight bit to clear the jig then trial and error (some measurement too
) to drill a 1/4" hole in the jig the correct distance from the bit to pivot the router around and end up with a circle the correct size. (Note numerous holes for different size holes) Bessey clamps really help on getting square glue ups on panels with no room to spare...even then it was a close run endeavor.
Last pic is the start of the supra baffles. I did make a mistake with the circle jig on one of the port openings but had enough scrap MDF to make a new one
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Baffle time
Now for the supra baffles...used the pattern included in the plans and traced onto the piece a screwed up with the circle jig. This made the pattern which I cut out on a bandsaw and then sanded smooth. Marked the center of the pattern and drilled 1/4" holes for the circle jig shown earlier. Make sure you start at the largest diameter (makes the recess for the driver) then work in until you rout all the way through on the final cut. I also used 1/4" holes drilled in the front to ensure alignment with the baffles. If you do this make sure you do not drill all the way through the baffle face.
Now for the supra baffles...used the pattern included in the plans and traced onto the piece a screwed up with the circle jig. This made the pattern which I cut out on a bandsaw and then sanded smooth. Marked the center of the pattern and drilled 1/4" holes for the circle jig shown earlier. Make sure you start at the largest diameter (makes the recess for the driver) then work in until you rout all the way through on the final cut. I also used 1/4" holes drilled in the front to ensure alignment with the baffles. If you do this make sure you do not drill all the way through the baffle face.
Too early for praise
Thank you for the compliments...but I didn't follow directions and the supra baffles are small enough that the round-overs ate into the lip that surrounds the drivers. Probably won't make an audio difference (at least that I'll be able to tell) but the visual rough edge will be highlighted I'm afraid.
I've assemble the filters per Bob's instructions coupled with North Creek techniques (at least as far as I'm able to duplicated them). Pretty messy but nobody will see them. I'll not describe the values of the different components as that is Bob's work. I used silicon to adhere the inductor and the capacitor to the peg board while also using zip ties to hold while drying and for added insurance. Used crimp on connectors, soldered and then screwed to the peg board (countersunk underneath w/nylon nuts on top). Red and Green wires to driver; Yellow and Black to the binding posts. Bob, I'd appreciate it if you could check my schematic and ensure it is correct. TIA.
On with the pictures...
Thank you for the compliments...but I didn't follow directions and the supra baffles are small enough that the round-overs ate into the lip that surrounds the drivers. Probably won't make an audio difference (at least that I'll be able to tell) but the visual rough edge will be highlighted I'm afraid.
I've assemble the filters per Bob's instructions coupled with North Creek techniques (at least as far as I'm able to duplicated them). Pretty messy but nobody will see them. I'll not describe the values of the different components as that is Bob's work. I used silicon to adhere the inductor and the capacitor to the peg board while also using zip ties to hold while drying and for added insurance. Used crimp on connectors, soldered and then screwed to the peg board (countersunk underneath w/nylon nuts on top). Red and Green wires to driver; Yellow and Black to the binding posts. Bob, I'd appreciate it if you could check my schematic and ensure it is correct. TIA.
On with the pictures...
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
On with the build pics...
Up next is assembling the speakers. Use lots and lots of clamps...probably can't have too many. Check all joints with the best square you have.
(note bottom needs to be tapped square with the front)
(Used a piece of plywood along the bottom to help keep everything aligned, should have used one on the top as well)
You could also clamp it dry, drill 1/4" holes in all the pieces then disassemble, glue, insert 1/4" dowels and cut flush. If you use dowels make sure you glue them in and then let them expand out for a significant period of time (weeks/months) then trim flush again.
Do this with the top, both braces, and the bottom.
Up next is assembling the speakers. Use lots and lots of clamps...probably can't have too many. Check all joints with the best square you have.
(note bottom needs to be tapped square with the front)
(Used a piece of plywood along the bottom to help keep everything aligned, should have used one on the top as well)
You could also clamp it dry, drill 1/4" holes in all the pieces then disassemble, glue, insert 1/4" dowels and cut flush. If you use dowels make sure you glue them in and then let them expand out for a significant period of time (weeks/months) then trim flush again.
Do this with the top, both braces, and the bottom.
rjbond3rd, Glad to hear your description, sounds like what I'm looking for...I listen mostly to Mark Knopfler/Dire Straits and girl/guitar; nothing very heavy and based on what Bob describes as their capabilities I felt this would be a very rewarding project. If anyone has any questions on the build I'll do my best to answer. Bob, I've tried to be careful on the filter pictures but let me know if you'd rather have them removed. Thank you for producing an eminently build-able speaker, can't wait to hear them!
Assuming that you used the specified 3/4" round-over and the supra baffle is 10" wide, the flat will be 8 1/2" and ever so slightly less than the diameter of the driver frame. So you WILL have a slight depression where the round-over overlaps the cut-out. When you finish the supra-baffle, the indentation will have a nice sharp edge and will look like a design feature. I did this to keep the width as small as possible.
The picture of the contour filter looks right. I know that many loathe the thought of an iron core inductor, but I chose the Erse Super-Q because of its very low DCR. Increasing the DCR with an air core inductor will change the alignment. It probably won't make much difference if you are using a stout SS amp, but if you use a high-Z amp, you may have to retune the speaker.
Bob
The picture of the contour filter looks right. I know that many loathe the thought of an iron core inductor, but I chose the Erse Super-Q because of its very low DCR. Increasing the DCR with an air core inductor will change the alignment. It probably won't make much difference if you are using a stout SS amp, but if you use a high-Z amp, you may have to retune the speaker.
Bob
Great pics and thanks for the detail!! Those are shaping up to be a fantastic set of speakers
One question, and this may not be the proper place to post this so if so just let me know, why does everyone use Cat5 wire? The quality of the wire is fine but nothing special. Its 24awg and depending on which color codes your using, the twist ratio varies. Is there a specific color code people use and or why Cat5? I've seen people make wires from braiding multiple Cat5 cables together to get a larger overall conductor while creating cancellation with the 90 degree angles. I've never seen people use just a single 24awg pair of wire and it seems its only done with single driver setups.
Sorry, I've seen a number of people doing this and saw your wiring so I thought I'd ask. I can move my question to another thread if deemed more appropriate.
Scott
One question, and this may not be the proper place to post this so if so just let me know, why does everyone use Cat5 wire? The quality of the wire is fine but nothing special. Its 24awg and depending on which color codes your using, the twist ratio varies. Is there a specific color code people use and or why Cat5? I've seen people make wires from braiding multiple Cat5 cables together to get a larger overall conductor while creating cancellation with the 90 degree angles. I've never seen people use just a single 24awg pair of wire and it seems its only done with single driver setups.
Sorry, I've seen a number of people doing this and saw your wiring so I thought I'd ask. I can move my question to another thread if deemed more appropriate.
Scott
Damping and insulation
Just followed the directions, used hardibacker secured with liquid nails. Used an utility knife to score the hardibacker...not the smoothest edges but cheap, easy and quick. Make sure you have enough space for all the edges, especially the unattached side, remember you'll be adding insulation as well. I did not do the top or bottom but everything else got the treatment.
Used a hammer drill to drill the holes...super slick. A masonry bit in the jigsaw allows smooth worry free cuts in the hardibacker. Cut to within 1/8 to 1/4 inch of the port hole then used a spindle sander to even it all up.
Just followed the directions, used hardibacker secured with liquid nails. Used an utility knife to score the hardibacker...not the smoothest edges but cheap, easy and quick. Make sure you have enough space for all the edges, especially the unattached side, remember you'll be adding insulation as well. I did not do the top or bottom but everything else got the treatment.
Used a hammer drill to drill the holes...super slick. A masonry bit in the jigsaw allows smooth worry free cuts in the hardibacker. Cut to within 1/8 to 1/4 inch of the port hole then used a spindle sander to even it all up.
A confession
Got in a hurry to hear how these things sound so I didn't take any pictures of the insulation installation but it cuts easy with a knife and glues on with Super 77 without any problems. Again make sure you leave room for all the pieces to fit together along the edges.
Soldered the speaker wires to the drivers installed the binding posts and then the filters and drivers.
Hooked it up to my DIYTube ST-35, a little Mark Knopfler "Get Lucky" and...
Unbelievable sound, they may never get finished because I don't think I can bear to put them out of service for that long!!!!! I'm now a FR convert!
Great listening room (not really) but they sound great anyway!
Bob, Thank you for such a great set of plans and awesom sounding speakers, I may have to build another set for HT.
Got in a hurry to hear how these things sound so I didn't take any pictures of the insulation installation but it cuts easy with a knife and glues on with Super 77 without any problems. Again make sure you leave room for all the pieces to fit together along the edges.
Soldered the speaker wires to the drivers installed the binding posts and then the filters and drivers.
Hooked it up to my DIYTube ST-35, a little Mark Knopfler "Get Lucky" and...
Unbelievable sound, they may never get finished because I don't think I can bear to put them out of service for that long!!!!! I'm now a FR convert!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Great listening room (not really) but they sound great anyway!
Bob, Thank you for such a great set of plans and awesom sounding speakers, I may have to build another set for HT.
Frequency response
Don't have a neat graph or anything but using a frequency generator (uncalibrated Iphone app "Freqgen") I can hear it at 20hz, it really starts coming on strong around 26-28hz at which point it is very usable and I can hear it to 16Khz which is the limit of my hearing. I'm very impressed, way better than I thought they'd be in the bass department.
Don't have a neat graph or anything but using a frequency generator (uncalibrated Iphone app "Freqgen") I can hear it at 20hz, it really starts coming on strong around 26-28hz at which point it is very usable and I can hear it to 16Khz which is the limit of my hearing. I'm very impressed, way better than I thought they'd be in the bass department.
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