The FR125-Spiral project has begun! - diyAudio
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 25th September 2005, 10:47 AM   #1
diyAudio Member
 
Join Date: Aug 2005
Default The FR125-Spiral project has begun!

Hi all

I'm sure some of you have seen the so called Spiral Horn design to speaker box enclosure as outlined by M. Takenaka in his website. On one of its pages he went into saying that higher Qts speakers in general should work very well in a Spiral Horn design, although failing to give theoretical justifications. Well, when I think of high Qts I think of the W/FR125S speakers from CSS (being from BC after all), so I decided to go for a spiral horn speaker for my newly planned computer audio rig. Hopefully this would also help complement Dave's growing list of viable FR125S box plans.

I've contacted Mr. Takenaka and he mentioned having heard OF these new CSS speakers. His suggestion was to build a Linear Model L100 spiral horn (from his website) with some slight enlargements to the box. The spiral itself, he said, need not be re-calculated. This is perfect since the L100's height of ~45cm is the height of most 19" LCD monitors, including mine. These should therefore be asthetically pleasing as computer speakers, provided that the bass is not too overwhelming for near-field.

What can I say? Why do it when the FR125S has already very good bass in BR enclosures? Dare to be different I guess. I am making these out of curiosity more than anything else.

I dropped by my local Home Depot this evening to buy the pipe segments and the winding wire for the spiral, as well as ordered a piece of 4'x4' ply to be cut to my plan. The lumber person grumbled somewhat but eventually succumbed to my endless barrage of "it's just straight cuts" Don't let them stop you from exploiting them!

More to follow, including parts details and pics when I wake up tomorrow...


NOTE: Does anyone have experience building enclosures using LePage's "No More Nails" adhesive? I was hoping to get away without buying any clamps for this project...
  Reply With Quote
Old 25th September 2005, 11:37 AM   #2
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
Hmmm, I never seen that before. Looks to me like it'd just act like a looooong port. Good luck and let us know how it sounds!

As for the glue, I tried it on a hardwood (oak) and will stick to yellow glue and clamps. Might work gangbusters on softwood or MDF though.
  Reply With Quote
Old 28th September 2005, 12:50 PM   #3
theNoid is offline theNoid  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Rock River, WY
Send a message via Yahoo to theNoid
A quick look without research look slike you are simply dividing your port into two sections, effectively making it a dual port design, requiring longer lengths, which is where the spiral helps. Yes? No? Maybe?

Noidster
__________________
"Mmmmm......Beeeer"
  Reply With Quote
Old 29th September 2005, 07:44 AM   #4
diyAudio Member
 
Join Date: Aug 2005
Quote:
Originally posted by theNoid
A quick look without research look slike you are simply dividing your port into two sections, effectively making it a dual port design, requiring longer lengths, which is where the spiral helps. Yes? No? Maybe?

Maybe. From what I understand, the original builder set out to create an alternative construction method for rear-loaded horns. He ended up with a horn constructed in a spiraling manner which seem to exhibit 2 advantages:

1) Easy to build with no need of advanced woodworking skills beyond those of building a rectangular box

2) Elimination of standing waves and distortion inside the horn via absence of angular corners and parallel planes

Whether these assertions are true stand to be tested. I'm merely making these out of curiosity. Mr. T seemed to have discovered that this box type operates more on the principles of BR rather than a horn, but the fluid dynamics of a conch-like shape seem to have overcome the problem of conserved sound energy in a BR (ie, low Fh means that the lower range needs to borrow energy from across the wave spectrum, resulting in sags in SPL/Frequency)
  Reply With Quote
Old 1st October 2005, 09:53 AM   #5
Nanook is offline Nanook  Canada
diyAudio Member
 
Nanook's Avatar
 
Join Date: Feb 2004
Location: Chinook Country.Alberta
Default the spiral horn..

I spent the better part of a month (actually two weeks if I can remember correctly) tearing the theory of the spiral horn down into something that I could understand. I think if you look at the "spiral horn" as a port, that is the beginning. The port is not divided into two (look at the paths very carefully). The port is a Hemlholtz resonator. Tune it to the Fs of the driver, using whatever software or mathematics you have at hand. Now look at the port as its own system. try to create a spiral horn that will fit the port when wound in Mr. T's fashion, and tune THAT horn to the same frequency.

I think it is a special kind of hybrid. But it does make sense. Tune the port to a frequency, create a horn within the port to "amplify the frequency", and you will get an acoustic gain of that frequency.

Maybe I'm missing it completely but I don't think so. Good luck
If you've completed them , how have you found them to be ?
__________________
stew -"A sane man in an insane world appears insane."
  Reply With Quote
Old 10th November 2005, 08:54 AM   #6
diyAudio Member
 
aletheian's Avatar
 
Join Date: Apr 2004
Location: Philly
Default How's the project goin'

I'm considering building a spiral port myself... loosely based on the same project, but with a pair of cheapie HI-Vi B3s'. They seem to be a nice combo of lowish Fs and high-ish Qts, so theuyll make a good cheap test subject.

I was thinking of tweaking the box to make it more golden-ratio-ish, and redoing the math on the port and spiral... I'd be interested to hear how yours is going.
__________________
Heghlu'meH QaQ jajvam!
  Reply With Quote
Old 10th November 2005, 09:20 AM   #7
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
I wonder if there's a way we can work out some of this using Martin's MathCad worksheets.
On the subject of No More Nails, ordinary carpenters glue only requires around 15psi to set like rock, and you can easily achieve this with something as simple as masking tape. I built a pair of cabinets using the folding mitre technique Terry Cain mentions, and it works perfectly. Also, the glue, as it drys, provides around 5psi of pressure / suction itself, helping still more. So this no more nails stuff could be worth a shot.

Scott
__________________
Community sites www.frugal-horn.com http://frugal-phile.com/
  Reply With Quote
Old 10th November 2005, 09:33 AM   #8
diyAudio Member
 
Join Date: Aug 2005
The construction was put on a halt when midterms and stuff came up... I'll be finishing it up soon

Cabinet construction with just 2 clamps and a hand drill requires a lot of enginuity
  Reply With Quote
Old 10th November 2005, 10:39 AM   #9
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
And patience.

It'll take you several days what could be done in one.

Ask Santa for more glueclamps Click the image to open in full size.
  Reply With Quote
Old 10th November 2005, 11:09 PM   #10
diyAudio Member
 
aletheian's Avatar
 
Join Date: Apr 2004
Location: Philly
I posted some musings on the spiral math in another thread:
http://www.diyaudio.com/forums/showt...989#post763989

it seems like a cool design to me, if it is implimented properly... I have 2 amps to finish building, and then I can get down and dirty with some carpentry... yaaaay!
__________________
Heghlu'meH QaQ jajvam!
  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
813 Project has begun ! Steven-H Tubes / Valves 2 27th June 2007 07:14 PM
Spiral Shaped Transmission Line Enclosure Project Complete kneadle Multi-Way 45 4th November 2004 01:30 AM
The quest to fix my amp has begun! wintermute Solid State 25 22nd December 2003 08:11 AM


New To Site? Need Help?

All times are GMT. The time now is 07:37 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