man it looks pretty good. exciting to see it come together, eh?
indeed it sure is squat compared to the drawings. i notice a couple places the angles between the pieces don't quite look right, but it may be due to the aforementioned saggy tape joints. double check, though, that each piece is angled 'up' from the previous one.
i believe 5/8" is as close as you're going to get to the right arc distance for 11°. the formula is
arc length = 11*(pi*6.375/360)
which ends up being ~0.612. 5/8 is .625. close enough for government work.
also, a note regarding gluage: consider gluing all the pieces by pairs. then assemble the pairs by pairs. seems kindof silly to do it by adding one piece at a time.
say your pieces are labeled a-k:
the first night, glue
a-b, c-d, e-f, g-h, i-j
together. the next night,
ab-cd, ef-gh, ij-k
then
abcd-efgh (ijk)
then the whole thing.
that'll be 4 days. unless the pieces are just too unwieldy. in which case, ignore everything i just said.
keep on truckin
/andrew - presents you with this spiral from architect Bruce Goff. the Bavinger house near tulsa, OK.
indeed it sure is squat compared to the drawings. i notice a couple places the angles between the pieces don't quite look right, but it may be due to the aforementioned saggy tape joints. double check, though, that each piece is angled 'up' from the previous one.
i believe 5/8" is as close as you're going to get to the right arc distance for 11°. the formula is
arc length = 11*(pi*6.375/360)
which ends up being ~0.612. 5/8 is .625. close enough for government work.
also, a note regarding gluage: consider gluing all the pieces by pairs. then assemble the pairs by pairs. seems kindof silly to do it by adding one piece at a time.
say your pieces are labeled a-k:
the first night, glue
a-b, c-d, e-f, g-h, i-j
together. the next night,
ab-cd, ef-gh, ij-k
then
abcd-efgh (ijk)
then the whole thing.
that'll be 4 days. unless the pieces are just too unwieldy. in which case, ignore everything i just said.
keep on truckin
/andrew - presents you with this spiral from architect Bruce Goff. the Bavinger house near tulsa, OK.
Attachments
Hey... I'm impressed...
About assembly... if your cut lines are clean.. and your joints have reasonably good contact.. I would certainly try pvc cement.. it worked pretty good with the little test model that I made.. don't forget to use the pvc cleaner.. The pvc cement will hold in a matter of minutes.. I think you'll find that that is a good thing... because it will be difficult to clamp these pieces.. I think your going to have to do this part pretty much by hand.
I think that you'll want to 'stuff' the pipe as you assemble it, because it will be difficult to get your hands up in there once it's glued up. (don't forget to run your speaker wire as well...at least if you put the stuffing in)
Also note that you could probably add a couple of degrees to the twist if you really wanted to strech out the spiral.. though I think I would probably try to get the best match possible.
Have you given any thought to the baffle for your speaker mount? I know you wanted to use the T.. and it seems like a good idea.. but how do you plan to orient it? Also, what do you plan to use for a tweeter..or will this be a co-axial design? (I've forgotten what drivers you intend to use).. Where do you plan to mount the crossover?
The reason I ask is that you may want to make provisions before you start gluing.. anyway... I'm still impressed..
About assembly... if your cut lines are clean.. and your joints have reasonably good contact.. I would certainly try pvc cement.. it worked pretty good with the little test model that I made.. don't forget to use the pvc cleaner.. The pvc cement will hold in a matter of minutes.. I think you'll find that that is a good thing... because it will be difficult to clamp these pieces.. I think your going to have to do this part pretty much by hand.
I think that you'll want to 'stuff' the pipe as you assemble it, because it will be difficult to get your hands up in there once it's glued up. (don't forget to run your speaker wire as well...at least if you put the stuffing in)
Also note that you could probably add a couple of degrees to the twist if you really wanted to strech out the spiral.. though I think I would probably try to get the best match possible.
Have you given any thought to the baffle for your speaker mount? I know you wanted to use the T.. and it seems like a good idea.. but how do you plan to orient it? Also, what do you plan to use for a tweeter..or will this be a co-axial design? (I've forgotten what drivers you intend to use).. Where do you plan to mount the crossover?
The reason I ask is that you may want to make provisions before you start gluing.. anyway... I'm still impressed..
faustian bargin said:
Thanks for the pic. Just wanted to mention that this assembly method is exactly what I described when I said "subassembly." http://www.diyaudio.com/forums/showthread.php?postid=126937#post126937 Glad to know we're on the same wavelength.
Dave
steve said:
The "human element" I mentioned a while back might throw a wrench in the works. A SMALL wrench. Every once in a while, I can't get a clean joint. I was always going to sort of "fill in" the joint.
See, here's how I think. I can use plaster of Paris, but it occurs to me that plaster of paris speaker enclosures are kind of rare.
Also, I should mention that I haven't started my morning I.V. of coffee (I wish. Can't believe we still take coffee orally).
Anyway, I need a "fill in" material.
Dave
steve said:
Thanks for the heads up. I had actually thought of everything EXCEPT running the wire through stuffing.
I do know how to orient the T, and it is crossed over to a tweeter. The driver is a Vifa P17-WG-00-06. It is crossed over at 2 or 3 kHZ (can't remember exactly) to a Vifa D27-TG-00-06. The tweeter is its own problem. Not sure how to mount that, but my understanding is that it doesn't actually NEED an enclosure.
The sweet thing about the Tee is that it can serve as a sort of electronics depository. There's three inches of space that are just sitting there, waiting for a crossover.
Oh yeah. The woofer fits EXACTLY on the tee, like they were made for each other. I'm going to get some felt material, but that's all I should need for a tight fit.
And your encouragement is much appreciated.
Dave
I hear you about the 'human element'.. one suggestion for cleaning up those joints would be to get a sheet (8x10) course sand paper (80 grit) and glue this sheet to a flat surface... then sand your cuts on this plane... Even if you are left with some filling... I still think there may be advantages to using the pvc cement..
I used bondo body filler on my speakers... it bonds very well.. and I've had no problems with shrinkage..I have had problems with shrinkage where I've joined pvc with other materials.. speaking of other materials... because of problems with resonance I lined my pipes with felt... I think I used driveway sealer to attach the felt (not recommended).. but before you glue up your pipes this might be something to consider..
regarding the tweeter.. I see two options.. to mount it on a baffle with your woofer.. the baffle is then mounted to the T. or you could build a mount off the other end of the T.. perhaps a short piece of 2" pvc with an elbow... at least it would match.
I used bondo body filler on my speakers... it bonds very well.. and I've had no problems with shrinkage..I have had problems with shrinkage where I've joined pvc with other materials.. speaking of other materials... because of problems with resonance I lined my pipes with felt... I think I used driveway sealer to attach the felt (not recommended).. but before you glue up your pipes this might be something to consider..
regarding the tweeter.. I see two options.. to mount it on a baffle with your woofer.. the baffle is then mounted to the T. or you could build a mount off the other end of the T.. perhaps a short piece of 2" pvc with an elbow... at least it would match.
lined with felt, eh? Sounds like a great idea. I should be able to pick that up at a fabric store.
Here's a pic. My hand shows where the three inch space is, where the electronics will be housed.
The woofer will fire straight down the pipe from one of the ends. I was thinking of mounting the tweeter on the side of "t" part of the tee with a strip of velcro, parallel with the woofer. On the outside part where my hand is, you see.
Here's a pic. My hand shows where the three inch space is, where the electronics will be housed.
The woofer will fire straight down the pipe from one of the ends. I was thinking of mounting the tweeter on the side of "t" part of the tee with a strip of velcro, parallel with the woofer. On the outside part where my hand is, you see.
Attachments
FYI, I reassembled the first enclosure two at a time, without trying to do anything but make each piece line up as flush as possible. Then I assembled all the subassemblies (this is all duct tape still). The angle is MUCH more exaggerated, almost 11° 🙂.
Dave
Dave
kneadle said:
Craft felt is usually a polyester. If you can get real wool felt it will probably work better. In this case i suspect the glue has as much to do with damping as the felt.
dave
planet10 said:
Two questions about that:
1) I had been thinking of buying some fabric, like curtain fabric, and making a glue bath for it. I would soak it in the bath, then line the inside of the enclosure. Would that do?
2) How much does something like that or wool-felt contribute to the stuffing density in TL, if at all?
Dave
The felt that I used in my speakers was actually roofing felt..usually called tarpaper.. it is very dense.. I had an extra roll left over from roofing my garage.. I would think that any reasonably dense material would work.
kneadle said:
Wool felt of sufficient thickness would contribute to the stuffing. My BD-Pipes use a lining of ~3/8" wool-felt and a little bit of dacron wool in the point for stuffing.
dave
I doub't that a felt material would significantly contibute to the stuffed pipe effect.. though it may have a tendency to absorb higher frequency sounds.. this would be a good thing... as the pvc has a tendency to ring..
As for gluing up some fabric... I think that is pretty much what I did.. only I used asphalt sealer. The idea would be to provide a layer of material with a different resonance. Quite honestly, I really don't know how much affect this will have on the sound quality of the enclosure... It will make them heavier.. and generally that is a good thing..
As for gluing up some fabric... I think that is pretty much what I did.. only I used asphalt sealer. The idea would be to provide a layer of material with a different resonance. Quite honestly, I really don't know how much affect this will have on the sound quality of the enclosure... It will make them heavier.. and generally that is a good thing..
ok.. I think that real wool felt of sufficient thickness could contribute significantly to the stuffed pipe effect..
I can now happily verify, faustian bargin, that the 11° works as designed. Whew! It took me FIVE segments to test it, so I was sweatin' bullets, but it's a go!
Yes, I took most of the day off to do this. I can do that.
Dave
Yes, I took most of the day off to do this. I can do that.
Dave
Kneadle:
I don't know if yo have commenced gluing yet, but I have a recommendation for great stuff if you have not.
PC7 and PC11 are epoxy glues that are rock hard and stick to PVC. I just got off the phone with the tech guy, and PVC it does work on.
I have used both, not on PVC but on other things, and forget about comparing these to other epoxy products. It cures rock hard, and holds like you wouldn't believe. Thick, it fills in slight indentations and can be sanded, primed and painted.
Available at "real" hardware stores, and probably True-Value types, though not sure about that.
PC7 has an hour working time, does not require clamping, and cures for service from 12 hours to 24 hours.
PC11 has 1/2 hour working time, does not require clamping,should be ready for service in 12 hours-assuming you are storing these anywhere near room temp. The major difference from PC7 is that it mixes with and works in water-very popular with marine people.
I don't know if yo have commenced gluing yet, but I have a recommendation for great stuff if you have not.
PC7 and PC11 are epoxy glues that are rock hard and stick to PVC. I just got off the phone with the tech guy, and PVC it does work on.
I have used both, not on PVC but on other things, and forget about comparing these to other epoxy products. It cures rock hard, and holds like you wouldn't believe. Thick, it fills in slight indentations and can be sanded, primed and painted.
Available at "real" hardware stores, and probably True-Value types, though not sure about that.
PC7 has an hour working time, does not require clamping, and cures for service from 12 hours to 24 hours.
PC11 has 1/2 hour working time, does not require clamping,should be ready for service in 12 hours-assuming you are storing these anywhere near room temp. The major difference from PC7 is that it mixes with and works in water-very popular with marine people.
kelticwizard said:
Since I'll be running water through these speaker enclosures (did I mention that?) that's big plus.
Thanks a million, once again, mr. wizard.
Dave
LOL, if these things don't work out, who knows what use you might find for some well made, sturdy PVC pipe spirals?
I am reminded of the comments of the well-known, excellent audio author David Weems. The first edition of his book, Designing, Building and Testing Speakers came out in 1980, before various things were understood about the Transmission Line. Throughout the chapter on Transmission Lines, Weems emphasized the strictly hit-and-miss character of the enclosure, as opposed to the very predictable closed box and vented box.
He has since changed his opinion of the Transmission Line, due no doubt, to the response becoming more predictable.
However, he ended the Transmission Line chapter of the first edition of his first book with the quote, (as near as I can remember), "There is a pronounced tendency for enclosures which were originally built as Transmission Lines to end their life as something else, such as doghouses".
I am reminded of the comments of the well-known, excellent audio author David Weems. The first edition of his book, Designing, Building and Testing Speakers came out in 1980, before various things were understood about the Transmission Line. Throughout the chapter on Transmission Lines, Weems emphasized the strictly hit-and-miss character of the enclosure, as opposed to the very predictable closed box and vented box.
He has since changed his opinion of the Transmission Line, due no doubt, to the response becoming more predictable.
However, he ended the Transmission Line chapter of the first edition of his first book with the quote, (as near as I can remember), "There is a pronounced tendency for enclosures which were originally built as Transmission Lines to end their life as something else, such as doghouses".
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