Stackable ribbon module - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

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 21st August 2011, 10:20 AM   #1
brunob is offline brunob  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Erlangen, Germany
Default Stackable ribbon module

I have built a very simple module that can easely be stacked on top of another to build a long line array. The idea is to use the two steel tubes that will fit on two long steel bars.

The ribbon area is 20 cm x 1.2 cm (or 1.0 cm). The steel frame is 22 cm long.

One of the picture shows a ribbon of 0.8 microns thick (no breathing allowed near the ribbon!). Aluminium foils provider: Foils List.

Magnet: 1.4 x 1.5 x 5 cm , N48.
Magnetic field strength: 0.74 and 0.64 T for the 1 cm gap; 0.70 and 0.58 for the 1.2 cm gap. The smaller value is for the middle of the gap, the larger for the magnet surface. Measurement were performed with a Hirst GM05 gaussmeter.

Frerquency response measured at a distance of 52 cm with ARTA.
Attached Images
File Type: jpg HPIM0630.JPG (343.9 KB, 795 views)
File Type: jpg HPIM0628.JPG (376.4 KB, 731 views)
File Type: jpg HPIM0629.JPG (393.9 KB, 714 views)
File Type: png 0.8 m.png (36.7 KB, 687 views)
  Reply With Quote
Old 21st August 2011, 10:41 PM   #2
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
Why not one long run ? disadvantage , advantages with stacking .......
  Reply With Quote
Old 21st August 2011, 11:50 PM   #3
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Quote:
Originally Posted by a.wayne View Post
Why not one long run ? disadvantage , advantages with stacking .......
I think the chosen 12mm width is about optimal
magnet field weakens beyond that

and with 12mm a long ribbon becomes hard to handle
mechanical constructing is easier as well

but you get higher Fs with short ribbon
but quite good if it does 1khz
  Reply With Quote
Old 22nd August 2011, 10:25 AM   #4
brunob is offline brunob  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Erlangen, Germany
Quote:
Originally Posted by a.wayne View Post
Why not one long run ? disadvantage , advantages with stacking .......
Good question.

Advantages:

- safety: putting together two long rows of magnets is difficult and dangerous because of the strong forces involved
- less weakening of the magnetic field with the increases of the ribbon length
- more choice for the ribbon material (e.g. 2.5 microns, 25 x 25 cm sheet from Lebowfoils)
- I plan to build a straight line and a concave line and compare both

Disadvantages:
- magnetic field in the gap is not as homogenous
- comb filtering could occur if the dead space separating the ribbon radiation areas is too large
  Reply With Quote
Old 23rd August 2011, 11:03 AM   #5
brunob is offline brunob  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Erlangen, Germany
Default concave line array

Has anyone experience with a concave line array of ribbons?
  Reply With Quote
Old 25th August 2011, 06:00 PM   #6
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
I'm going to build a short ribbon and compare .. currently have a 1200MM x42mm mid-range prototype and will compare it's efficiency to say a 350mmx42mm.


we will see....

Last edited by a.wayne; 25th August 2011 at 06:02 PM.
  Reply With Quote
Old 3rd October 2011, 10:20 AM   #7
brunob is offline brunob  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Erlangen, Germany
Default Dip at 4 KHz

The frequency response of my ribbon modules shows a dip at about 4 to 5 KHz.

I wonder where this dip is coming from?

If I would increase the width of the left and right sides of the ribbon module, by attaching another 2 x 2 cm rectangular tube on each side (see pictures in the first post of this thread), then the frequency of the dip would go lower. The frequency responses are shown in the first picture atached to this post.

If I cover the back of the driver with felt, then the dip dissapears and the level at 2 KHz is slightly lower (second attached picture).

I first thought this effect was due to the diffraction from the edges. I don't think this is the cause of the dip because when adding felt in the back of the driver, the dip is strongly attenuated.

Attached Images
File Type: png 2 cm baffles.png (42.3 KB, 484 views)
File Type: png felt.png (23.3 KB, 102 views)
  Reply With Quote
Old 4th October 2011, 08:16 AM   #8
diyAudio Member
 
Join Date: Apr 2008
Quote:
Originally Posted by brunob View Post
The frequency response of my ribbon modules shows a dip at about 4 to 5 KHz.

I wonder where this dip is coming from?

If I would increase the width of the left and right sides of the ribbon module, by attaching another 2 x 2 cm rectangular tube on each side (see pictures in the first post of this thread), then the frequency of the dip would go lower. The frequency responses are shown in the first picture atached to this post.

If I cover the back of the driver with felt, then the dip dissapears and the level at 2 KHz is slightly lower (second attached picture).

I first thought this effect was due to the diffraction from the edges. I don't think this is the cause of the dip because when adding felt in the back of the driver, the dip is strongly attenuated.

Cavity resonance.
  Reply With Quote
Old 11th October 2011, 05:10 PM   #9
brunob is offline brunob  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Erlangen, Germany
Quote:
Originally Posted by Groove-T View Post
Cavity resonance.
Which cavity do you have in mind? Could you elaborate?
Thanks
  Reply With Quote
Old 11th October 2011, 05:46 PM   #10
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
use two, with a crossover around the dip
  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
DIY ribbon info requested (constructing a ribbon unit) SpinMonster Planars & Exotics 15 11th April 2011 08:27 PM
Endangered Audio - Gristleizer Module & New Module Line! endangeredaudio Vendor's Bazaar 0 5th March 2010 03:03 PM
Fountek ribbon tweeter 3cm2 ribbon black square alumunum faceplate lduarte1973 Multi-Way 3 16th June 2009 08:50 AM
AD21065L module ingrast Digital Source 0 12th September 2004 09:24 PM
LCD module? DJG Swap Meet 0 12th December 2002 11:01 PM


New To Site? Need Help?

All times are GMT. The time now is 09:12 AM.


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