I am currently building a set of HDTs.  Should be done soon, can't wait !!!  :D


Since many people have been so helpful to me on these forums (thanks very much !) I thought I would add a little bit and contribute something.

For anyone building the HDTs, one task you have to deal with is drilling the oval openings between chambers.  These are well detailed on the instructions from Decware.  However you have to work out how to drill all the 1/2" holes around the oval, I mean how many and where.  To do this task I used my PC to make a drilling template.  For those of you who would like a copy, I am making it available at the following location:

http://home.cogeco.ca/~rsolda/Audio/HDT/Templates/HDT_Oval_Template_2.pdf

You can print this pdf file out (be sure to print it out at 100% scale) and cut out the template rectangle (dotted lines) then simply draw horizontal and vertical lines through the center location of your oval on your work piece and tape the template using the cross hairs to center the position of the template.  I then used a punch to mark the centers of each of the small drill circles on the MDF, removed the template and used the 1/2" spade bit to drill them out.

To ensure that your oval is the right size when it prints, you can measure the rectangle. It should be exactly 8"x6" to be the right dimensions.

Hope it helps you DIY'ers out.  It is a great project to build but sure takes time to do it all.  Wonder what they will sound like?

I hope to post pictures when I am done.

Rick

Actually Brad the hole drilling and then "breaking" out the waste part leaving a jagged edge is an "on purpose" design aspect of the HDT. Steve claims it helps diffract waves and create beneficial "turbulances" as the rear wave enters the side chambers.

[quote author=Chris K  link=1130981033/0#2 date=1130982536]Actually Brad the hole drilling and then "breaking" out the waste part leaving a jagged edge is an "on purpose" design aspect of the HDT. Steve claims it helps diffract waves and create beneficial "turbulances" as the rear wave enters the side chambers. [/quote]

I have a hard time believing this given the lack of driver excursion with the FE206.  There isn't much air moving here to create "turbulances", at least ones significant enough to create an audible difference.  It's possible, but I just have a hard time believing  ???
Now with a driver like the MKII it's a (little) easier to swallow.

2sounz

  I printed @100% on two computers and 2 printers  and the ovel comes out  to be....3 3/4" X 5 5/8" on both. the linews you have drawen need to be close enough together to be able to break the center out after drilling with a good blow from a hammer. What you've show would be a little two far apart to work.


 The line that marks the centers should be 4" X 6"


   Thanks for your help with this, it'll make the build easier for all if we can get it right. I know when I print from my cad program to Adobe writer and then print on both computers its exactly 4" X 6" but it doesn't even work when I e-mail it to myself.

  I guess with your pattern, if someone was to just take and mark new lines to get the 4" X 6" size they needed, then make the same witness marks all the way around they could make it work just fine.  The division of the oval just needs to be divided in to smaller increments.

  Very good idea,


   BobZ.

[quote author=Zygi  link=1130981033/0#6 date=1131050410]....... I know when I print from my cad program to Adobe writer and then print on both computers its exactly 4" X 6" but it doesn't even work when I e-mail it to myself.

     BobZ. [/quote]
Just for grins guys, have you tried to email a TIFF instead of a .jpg or .pdf. As we all know compression does terrible things to a signal, and images as well.

Brad,
There are 2 types of "turbulence" to consider in a speaker box: the airfoille type when you are dealing with large amounts of air, like at low frequencies and also the "sonic" type like you have to account for at mid frequencies which are complicated by reflections inside the cab. I think the idea is to break up the mids by causing a sonic turbulence.

I'm sure someone will tell me if I'm FOS, but at the level of spl in most pro cabs I have experience with, breaking up mid freqs with turbulence is very important.

Chris,

Of course, you are absolutely correct. My thinking, like yours, is that it should be better to use a vector based format, especially a PDF, for any transfer of graphics. What's going on? I've transfered billboard graphics to printers, 3 or 4 on a floppy before, in Adobe and Corel with no losses or color shifts. I know it should work.

BTW, that's across different versions of each with no anomalies.

MOD:
After re-reading the thread, I removed my silly questions, since I misunderstood the problem to be email related, anyway.
Nice try 2Sounz, just .....  uhh ..... fix it and it will be helpful.

Maybe you have a better jigsaw, than I do. I have an effortless drill.

Is there a "Touche" smiley?  So true, but what's a/an SLO? I don't think I want one.