fiberglass TL

[pkitt]

I will see what I can do, but going from an F3 of ~25Hz to one of ~20 Hz will likely require a fairly large increase in volume. If I haven't posted anything here within the next couple of days, remind me with another post, okay?

pkitt:
i just designed a model according to your measurements, and two things ýmmediately shown up:
1 - the best shape for it resemples slightly a pipe, seen with the burning cavity facing backwards and the mouth piece facing upwards. the woofer would be on the "knee" (later i'll put this idea attached).
2- it's interesting as drawing this gave me the idea that if the pipe was bigger, it would be easier to build. do you mind simulating a bigger volume for a tappered pipe, please? if, for example, you can reach the 20Hz at -3dB that would be doubly perfect: bigger size and the desired 20Hz.

picowallspeaker:
i'm just imagining you a little bit like me, always with a notebook and from time to time registering there the "crazy" ideas that come in. what do you think of this "rising" pipe thing?

 

[pkitt]

Okay, a really big tapered TL for the L26

Okay, I increased the volume of the 15:1 tapered TL for the L26 by making the beginning area be 6.75 Sd and the ending area be 0.45 Sd. The only other change from the smaller tapered TL is that more stuffing is required; you now need 90 ounces uniformly distributed by density (1 lb/cu.ft.) in the first 37" of the line. The L26"s center is still 14" from the beginning of the line. Again, this is a really big line containing ~220 liters. I wouldn't want something this big but its F3 is just a smidgen over 20 Hz. I've attached the response graph.

pkitt:
i just designed a model according to your measurements, and two things ýmmediately shown up:
1 - the best shape for it resemples slightly a pipe, seen with the burning cavity facing backwards and the mouth piece facing upwards. the woofer would be on the "knee" (later i'll put this idea attached).
2- it's interesting as drawing this gave me the idea that if the pipe was bigger, it would be easier to build. do you mind simulating a bigger volume for a tappered pipe, please? if, for example, you can reach the 20Hz at -3dB that would be doubly perfect: bigger size and the desired 20Hz.

picowallspeaker:
i'm just imagining you a little bit like me, always with a notebook and from time to time registering there the "crazy" ideas that come in. what do you think of this "rising" pipe thing?

 

[brockzila]

i work in glass and have watched the utube link from earler and every thing he dose is a viable way of making a mold.
as for the cone you are talking about.
I have heard of the foam and petrol tech but it has to be the right type of foam. some will not melt enough and will stick in side your cone and others will melt with the heat as the resin goes off.
there is no way to make the mould in one go as removing the plug would be impossable. making it in sections is possable but again the bends would have to be perfectly constant or again it would mess things up.

when it comes to joins then you will be fine. a layer over the entire thing then a few coats of flow coat and you will be fine.


if the cone was straight, it would be all good but the fact that it wraps around a post.

well good luck.

i will help where i csan if you need any info on the glass side of things.

good luck keep us updated on the progress

 

[sergiof]

hello again, everybody,

as you can see in this thread, the idea of building two huge 3way loudspeakers came a little bit down as soon i decided to show the project to my girlfriend... it's a huge pair of speakers, so...

i changed my ways to a pair of 2 ways speakers (using both the W15CY and the fountek JP3), in a voigt pipe, that would be aided by a discrete "wall" subwoofer. this solves me some problems, and creates me others as well.

since i'm going to use the subwoofer below 100Hz (1st order cut, maybe), what do you think would behave better? the Seas L26RFX/P or the L26ROY (or any other)?

if it goes for the L26RFX/P, there's no need to bother pkitt (to whom i'm deeply thankful!); if it goes for the L26ROY...well...the TL becomes different, i believe...

thank you for your help, and please forgive me my constant change of mind!

(brockzila, i will really need your help and expertise in the "emphasis clone" project... if you think you can help me i'll be deeply thankful)

 

[picowallspeaker]

Surfing on the web -a sport with lots of fiberglass!- I found the site .

It made me thinking of a japanese I saw somewhere in the web space that built transmission lines with an helix inside a large PVC , with constant measure throughout the line

The link is http://www3.ocn.ne.jp/~hanbei/eng-intro.html