Requesting the voices of experience on box design

[bostarob]

I've got some drivers in a box that I threw together last summer before I went to school. They contain HiVi F8's, and Vifa D25AG domes. The box is too small and ugly, so this summer I want to build another one. I need some advice on driver, port, and bracing placement.

--I haven't a clue where to put bracing, and I'm not sure If the port is in the best place (although it is convenient), or the drivers. How much should I offset the tweeter?
-andy

Here are my current plans:

 

[jbateman]

If you want to try to optimize the response of the tweeter by offsetting it on the baffle, there is a program called BDS at http://www.pvconsultants.com/audio/frdgroup.htm which can help. I had difficulty using it myself, however.

I like rear ports , unless the speaker has to be placed against a wall. Any port resonances or out-of-phase midrange signals that escape thru the port will be less likely to be heard. As far as bracing, the object is to divide the long panels into smaller, unequally sized panels. So don't put a brace exactly in the middle, or divide a panel into equal thirds.

 

[navin]

a brace or 2 and you could turn this into a TL

 

[OMNIFEX]

You have the braces in the most vital part, around the woofer.


Your also using a ducted port, in which, the wood used
for the ports, will brace the box as well.

 

[bostarob]

Turn it into a TL? How would I do that? I'd have to do a little more research on TL design, but I am considering one of those as a possibility. How would the size of a TL for this driver compare to a vented enclosure (.75 - 2 cu.ft internal)?

also - what is the diameter of a T nut? I don't have any lying around. (#8 and #10)
Thanks
-andy

 

[Ilianh]

If you want to try to optimize the response of the tweeter by offsetting it on the baffle, there is a program called BDS at http://www.pvconsultants.com/audio/frdgroup.htm which can help. I had difficulty using it myself, however.

Sorry, a little off topic here, but I wanted to say that this spreadsheet is awsome for not too complicated designs.

Yes, its not very user friendly, but still better than speaker workshop gui wise .

The only thing that I want to do but cannot is use rounder sides ie. spherical enclosures.

Anyone knows how any online references? hardcore maths are not too much of a problem but I suspect physics will be in the background, ugh.

 

[JOE DIRT®]

Ilianh there are pletty of programs out there for speaker design that are really user friendly....almost every site has one...the critical thing is that you know the specs on the drivers and what you are trying to accomplish....I personally would start off with a simple 2 way design...then you can figure out what your lacking...there are so many variables involved that there is never the perfect answer....but I`m sure the knowledgible members here will help you with questions


Cheers!!The DIRT®

 

[mikee12345]

tlines are approx 1.7metres long for 50hz so not applicable unles for home theatre and u want stands but u can use the height of the thing to keep the speakrs at ear level and get some nice bass also :-D eg 90cm high towers.

well i know that keeping the front face as narrow as possible is good.
rounded off corners are good too.

il have to find my lost links-ive gone too far into subs and forgotn to keep up with the midrange tweeter stuff :-D

i think that 340/2 * the distance between faces gives u the box resonances ( i think! ) i must find that link too lol

 

[bostarob]

Ohh BTW, Omnifex - I compensated for port volume!
Also, will having the port at the bottom of the enclosure make it sound muddy?
-andy

 

[navin]

well i dont know what teh volumes would be i did not doany exact calculations besides the length of TL is usually related to your F3 and the area is realted to teh Sd of the woofer you can save a bit of volume by tapering the TL fro say 1.25XSd to 0.75XSd.

if you put a vertical partition between the port vertical and the front baffle and a horzontal partition below the woofer you can make a TL.

 

[OMNIFEX]

Ohh BTW, Omnifex - I compensated for port volume!

Thats The Spirit!!!!!!

Also, will having the port at the bottom of the enclosure make it sound muddy?
-andy

A port can be anywhere, providing its not obstructed.

So, no. You won't have any muddiness from having a
port on the bottom. Maybe a slight breeze when walking
barefoot next the port while its playing, but no muddiness.


Best Regards,

 

[Ilianh]

Ilianh there are pletty of programs out there for speaker design that are really user friendly....almost every site has one...the critical thing is that you know the specs on the drivers and what you are trying to accomplish....I personally would start off with a simple 2 way design...then you can figure out what your lacking...there are so many variables involved that there is never the perfect answer....but I`m sure the knowledgible members here will help you with questions

Hi, well basicly it's not that I dont understand the spreadsheet, I understand it perfectly . It's the fact I can't simulate Spherical enclosures baffle difraction with that, or more like an egg shaped baffle , concerning spherical enclosures I'd suspect a rippleless bds graph anyway.

I'm used to user hostile software , at college we sometimes use programs made by our own teachers for our works.. hehe

I've never seen a program that could simulate a sperical enclosure, What I'm trying for a is a "simple" vented design.

Martin J. King's (www.quarter-wave.com) mathcad models for vented designs are about the best simulations I've used. But even then, no spheres.

Anyone knows how a "ring" around the driver would affect baffle diffraction? Like on those designs.

http://www.audioexcellenceaz.com/cain.htm