Go Back   Home > Forums > Loudspeakers > Full Range

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 29th September 2012, 09:49 AM   #11
morgoe is offline morgoe  Australia
diyAudio Member
 
Join Date: Sep 2012
I don't have a huge amount of time to mess around with various designs unfortunately, so I've decided to take the BR/ML-TL Hybrid build here and change it into a U shaped design with my blocks. Does this sound feasible? Are there any particular things to keep in mind when I change the shape of the box, or should I just make sure to keep the volume the same?

This uses the Fountek FR88ex driver.

If you guys are able to confirm what I'm thinking and give me a "Yes this is a good idea" or "No stop horrible idea", then I'll go ahead and build a 3D Model so that I can put it together nice and easily.
  Reply With Quote
Old 30th September 2012, 12:59 PM   #12
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
A TL is probably the hardest system to build. I would not pick one for my first project, but what the heck, go for it.
  Reply With Quote
Old 2nd October 2012, 07:05 AM   #13
morgoe is offline morgoe  Australia
diyAudio Member
 
Join Date: Sep 2012
Why do you say that? The build in the PDF doesn't look too complex.
  Reply With Quote
Old 2nd October 2012, 09:15 AM   #14
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
It is easy to do a nice drawing. If it is an established design and you build EXACTLY what is drawn, then it is just woodwork. The physics of a TL are very complex. They are hard to tune, sensitive to stuffing densities, and from a woodworking side a lot more parts.

As this is your class project, not just building a nice pair of speakers, building someone else's published design is not what yo are looking for. I would think it would limit you in your block idea. Overly complex is kind of the opposite goal of industrial engineering. Aesthetics blended with creativity with the engineering to get a simple, pleasing yet effective, producible design.

I can build a very well engineered box-type speaker in an afternoon. They fail on the aesthetics part. You are looking to re-implement the second most complex box with a labor intensive assembly. When graded, think about the question of what does it do better?

Don't get me wrong. I have been thinking about what kinds of advantages in managing panel resonances your idea could help with. I may even make some test panels to do some measuring. I only suggest using the idea to make a unique shape from a simpler acoustic design first. There is a lot to learn about building speakers.

Bottom line is, you have lost a week on this forum where you could have done a couple of prototypes. Time to get sommething build.
  Reply With Quote
Old 4th October 2012, 10:37 AM   #15
morgoe is offline morgoe  Australia
diyAudio Member
 
Join Date: Sep 2012
Ok great. Thanks.

I actually started putting a prototype together this week (some of the pieces aren't flush - I did about 6 with a different and inaccurate method, but put them in there anyway.. all the newer ones are perfect). Pics:
Click the image to open in full size.

It's got the same volume as the design I posted, but semi-circular instead of rectangular. The issue I've got now is screwing every little piece together.. very difficult and time consuming. Is just glueing them together enough? Or could I thread long rods from top to bottom to keep them together?
  Reply With Quote
Old 4th October 2012, 11:35 AM   #16
mightym is offline mightym  United States
diyAudio Member
 
mightym's Avatar
 
Join Date: Feb 2008
Location: Checotah, Okrahoma former home of the Okra Fest
Gluing,

Since you are using bits that are aprox. the same size, and look to be same angle to each cut, glue the individual layers in circles ( only gluing the 2 half circles, not the entire circle, conversely you could glue the entire circle and cut into half circles after the adhesive has cured, this would give you a flat surface to attach the baffle to. ). When the layers have cured, then stack and glue the layers together.

The individual circles can be clamped with something as simple as a bit of string, or large elastic bands. The clamping force need not be excessive, just hold the bits together till the glue dries. Modern adhesives are generally stronger than the wood you will be joining anyway.

I would also probably put something on the top and bottom of the circles to keep the layers flat as the glue cured, this will make the stacking much simpler. If you have problems with the blocks moving about when the glue is still in the stage where its not tacky yet, an internal form could be constructed out of a simple cylinder of any material that will keep the blocks from moving 'till the glue sets.

I would also do the finish sanding of the outside surface of the blocks, and any staining, prior to glue-up. The "squeezle" ( Technical term for the glue that comes out of the joints, when clamped ) at the joints can be dealt with with careful scraping after it's cured, but glue's generally will not take stain.

Interesting concept, I'll look forward to seeing your final results.

John
  Reply With Quote
Old 5th October 2012, 09:03 PM   #17
philipc is offline philipc  South Africa
diyAudio Member
 
Join Date: Jul 2010
^^^ I concur

I've actually broken mdf boards trying to undo glues joints, so the glue is pretty strong.

How long till you have to submit the project?
  Reply With Quote
Old 7th October 2012, 03:51 AM   #18
morgoe is offline morgoe  Australia
diyAudio Member
 
Join Date: Sep 2012
The project is due on the 30th of October.

I went out and bought some second-hand wood (a requirement of the project is to use recyclable/second-hand materials) yesterday, massive rip-off but oh well. Not sure what wood it is, but its similar to Cedar, according to my Dad. Light, no warping, absorbent.. looks to fit my needs pretty well.

I've glued the pieces shown above just now, so we'll see how that turns out. Using a piece of string to hold the pieces in a perfect circle while it glues. Then I'll cut it in half after it dries.

I'm unable to find the FR88EX to buy anywhere online. I can find the FR89EX, and it looks very similar, can I slot it in this same design without many issues? I have to buy it soon - it'll take two weeks to get here and I only have 3 weeks left.
  Reply With Quote
Old 8th October 2012, 08:19 AM   #19
philipc is offline philipc  South Africa
diyAudio Member
 
Join Date: Jul 2010
With the available time left I would get what is available right now. The FR89EX is very similar to the FR88EX, you can use the same volume box, just change the vent length if you are going for the bass reflex design.

Some advice for 'free'. A good plan today is better than a perfect plan tommorow'!

I think for the object design class the emphasis is on the uniqness and design process and execution of the design. Correct me if I am wrong but the driver that you will be putting in the box is irrelevant, you could just use pc desktop speakers in the box, sound quality will only form a fraction of the total point allocation?

Keep us up to date with plenty of pics!
  Reply With Quote
Old 10th October 2012, 12:18 PM   #20
morgoe is offline morgoe  Australia
diyAudio Member
 
Join Date: Sep 2012
I've bought the FR89EX, it should be here within about two weeks. Not sure how I'll change the vent length, or how I calculate that? Don't need to worry about it for now.

Correct that the sound quality mightn't form much of the marks, but I also want something for my own personal use that'll sound as good as possible. I get to use this when its done!

I glued together the pieces I showed above, but the resulting structure was not very strong - I was able to break it just by squeezing the opposing sides of the circles. Is normal PVA glue enough? I can probably make it stronger by clamping it down and ensuring the blocks are forced into circle with a bit of elastic or something. Alternately, I could have little biscuits in between each blocks. I'd appreciate any advice here.

I've cut up 80 blocks out of my new wood, gotta cut another 20 tomorrow, then start glueing them together. I'll be glueing them into circles, then cutting them into semicircles (half through the glue line, half halfway through the block). 7 circles in total for 2 speakers. I'll then use the leftover wood I have to make the top/bottom/baffle out of planks. Sound like a good plan? Pics coming!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Unconventional speaker design - would this sound any good? morgoe Multi-Way 31 27th September 2012 07:14 AM
somewhat unconventional ESL design zweetvoetje Planars & Exotics 44 31st October 2010 02:12 PM
DIY unconventional speaker stands monstertrucker Multi-Way 9 27th September 2008 03:04 AM
Active multiway speaker design? leadbelly Multi-Way 12 23rd May 2007 11:52 PM
Unconventional subwoofer design BAM Subwoofers 19 28th December 2003 04:52 PM


New To Site? Need Help?

All times are GMT. The time now is 08:22 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2