Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

A DIY Ribbon Speaker of a different Kind
A DIY Ribbon Speaker of a different Kind
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 13th February 2018, 05:04 PM   #1191
borzi1024 is offline borzi1024  Hungary
diyAudio Member
 
Join Date: Aug 2016
To be honest I do not have real measuring mic too.
I use Panasonic WM61 capsule (3-4 $), connected to a modified USB sound card mi input. (CM6206 chip, new one around 10 $, I bought 2nd hand 4$)
Changed the coupling capacitors to higher value to have flat low freq. originally it starts to drop at 50 Hz.

I used it for my sub level adjustment and DRC at low freq. (measure with REW, create filters, export filter to convolver, play music with computer connected to HDMI digital amp with TI equibit chips)

Then I recognized it is quite accurate in the entire audio range.
I can measure my headphone up to 19.5 kHz

Even it is not a real calibrated instrument, can provide sufficient results.
Attached Images
File Type: png Senheiser HD555.png (82.5 KB, 88 views)
  Reply With Quote
Old 13th February 2018, 10:07 PM   #1192
WrineX is offline WrineX  Netherlands
diyAudio Member
 
WrineX's Avatar
 
Join Date: Mar 2004
Location: Den Haag
Quote:
Originally Posted by borzi1024 View Post
Hi,

I step forward with resonance and distortion problem.
Both of my prototype diaphragm (Canson paper and Xerox never tear) had similar behavior.
Resonate one low freq, and there is a big distortion on that frequency and a multiplication of it.
After try several things without real success I read again the patent US4903308 and implement solutions mentioned there.
The Canson paper distortion almost disappear and Xerox (more floppy material) improves a lot.
The phenomena and one solution is clearly written in the patent, and the described solutions works for me.
Wrine implement similar strips earlier.
I tried also with foam tape it was not working, fiber glass works.
I made a video of Xerox vibration (around 37Hz):
YouTube

"The present transducer as best seen in FIG. 1 will
have a resonant frequency dependent on the specific
transducer size and the material employed.As shown in
FIGS. 1 and 5, parallel strips of damping tape 73 are
adhered at predetermined locations on the inside of
each web end portion 24a, 24b, 26a and 26b. The strips
of tape, preferably made of a woven fiberglass such as is
found in strapping tape, aids in flattening the amplitude
response and reduces harmonic distortion resulting
from the device’s resonant frequency and its multiples.
Best results have been obtained with a damping tape
mass of about g of the mass of the diaphragm 22, divided
into strips spaced equidistantly apart from near the end
of each web portion to the edge of the central dia
phragm expanse. While three parallel damping strips
are shown, it will be appreciated that an increased num
ber of parallel damping strips spaced equidistantly but
closer together also works well."

Other thing is the damping of "elastomeric cords":
"The length of cord on each side of the expanse as indicated
at 65 in FIG. 2 determines the low frequency below
which the frequency response of the diaphragm is atten
uated. Such attenuation is desirable because the lower
frequency response in a diaphragm has a greater ampli
tude and must be attenuated to improve the overall
response. It has been determined that a cord length of 1;
inch, with the cord fastened l inch away from each side
of the expanse, satisfactorily attenuates frequencies
below 100 Hz."

you can see in the video the paper acts weird down low. it flaps around and does not follow signal very well ofc 37 hz is low of course but this happens higher up as well. to get lower best results i got was either going heavy. or add that thick foam window tape. that 4mm thick pvc stuff. but still it is in no way perfect. i got better results when i made the round parts out of bended and coated foam bord. while the middle part remaind a rubanoide coil former thing

YouTube


YouTube


Do note heavy eq used i believe. but not the weird wobbly paper thing going on. eq used is in the video or description

Last edited by WrineX; 13th February 2018 at 10:10 PM.
  Reply With Quote
Old 14th February 2018, 05:49 PM   #1193
borzi1024 is offline borzi1024  Hungary
diyAudio Member
 
Join Date: Aug 2016
Your double winding solution seems has under 1% THD from 800 Hz till 5 kHz.
Outside more.
I'm still wondering how to reach the mentioned under 1% distortion in entire range.

Tedlar membrane with fiberglass strips, 36 awg silver wire.
That's the secret? (or under 1% THD in entire 150Hz-20 kHz range is not true)

I hope Sergiu can measure soon again to see what distortion level he reached with Canson, alu coils, and special cuts.

I get first trial of alu tape coils cut with vinyl knife on DIY cnc machine.
Unfortunately it is useless because only a small part is ok, at least something and I hope he can cut it perfectly.
Attached Images
File Type: jpg Coil.jpg (384.1 KB, 73 views)
  Reply With Quote
Old 14th February 2018, 06:41 PM   #1194
WrineX is offline WrineX  Netherlands
diyAudio Member
 
WrineX's Avatar
 
Join Date: Mar 2004
Location: Den Haag
Quote:
Originally Posted by borzi1024 View Post
Your double winding solution seems has under 1% THD from 800 Hz till 5 kHz.
Outside more.
I'm still wondering how to reach the mentioned under 1% distortion in entire range.

Tedlar membrane with fiberglass strips, 36 awg silver wire.
That's the secret? (or under 1% THD in entire 150Hz-20 kHz range is not true)

I hope Sergiu can measure soon again to see what distortion level he reached with Canson, alu coils, and special cuts.

I get first trial of alu tape coils cut with vinyl knife on DIY cnc machine.
Unfortunately it is useless because only a small part is ok, at least something and I hope he can cut it perfectly.
i am pretty sure it is not true, since not one measurement was posted EVER, of a comercial ruba. also dispersion patern or polar plot sucks, never posted either but it is the truth. by the way silver wire >? why would anyone use that. besides being expensive it does not do a whole lot. alumnium would make more sence

one other thing you mic has to be able to even measure that low distortion. the Panasonic is as good as the noise floor to do so i had a umik and it llooked really flat in distortion but it was purely because it could not resolve lower distortion.

Last edited by WrineX; 14th February 2018 at 06:44 PM.
  Reply With Quote
Old 14th February 2018, 07:58 PM   #1195
borzi1024 is offline borzi1024  Hungary
diyAudio Member
 
Join Date: Aug 2016
Silver wire I read in patent US4903308.pdf. I do not know why it is good.
Maybe it works like the foam on rubber and fiberglass tape.

Mean time I made some progress.
Made 3rd diaphragm and assembly today:
Canson 125g/m2 with 0.17 diameter copper wire coil.
I put 4 fiber glass tape stripes on each wing.

It is the 1st rubanoid where I can enjoy the sound what is coming out!
I will put more tape later try to dump the resonance at 120 Hz.
It goes up to 17 kHz. Distortion is not that bad this time.(see close field measurement)

I upload 2 videos, playing with my DIY closed box sub crossed at 80 Hz.
Without equalization.
I start to trust, it is not waste of time to play with it. Click the image to open in full size.

Video1
Video2
Attached Images
File Type: png Canson_0_17_distrotion_close field.png (108.5 KB, 59 views)
File Type: png Canson_0_17_with_sub_listening_pos.png (114.7 KB, 58 views)
  Reply With Quote
Old 16th February 2018, 05:57 PM   #1196
ondesx is offline ondesx  France
diyAudio Member
 
Join Date: Apr 2008
Quote:
Originally Posted by borzi1024 View Post
Silver wire I read in patent US4903308.pdf. I do not know why it is good.
Maybe it works like the foam on rubber and fiberglass tape.

Mean time I made some progress.
Made 3rd diaphragm and assembly today:
Canson 125g/m2 with 0.17 diameter copper wire coil.
I put 4 fiber glass tape stripes on each wing.

It is the 1st rubanoid where I can enjoy the sound what is coming out!
I will put more tape later try to dump the resonance at 120 Hz.
It goes up to 17 kHz. Distortion is not that bad this time.(see close field measurement)
Hello,

The choice of silver is due to its good behavior to corrosion and oxydation. But, if the copper is completely enclosed after gluing it, it will do the job as well...

This driver needs attention on three main sectors :

Firstly, the centering of the coil in the double magnetic gap is very important. If there are variations during the movement of the coil, this will induce distorsions. It's thus of prime to find an elegant way to maintain centered the coil in the gap all the time, while keeping its free displacement... Not an easy task ! Most of the used methods aren't effective !

Secondly, the material and the final constraint of the webs are of paramount importance. Since the humidity changes will obviously modify the specs of paper and, thus, the sound, "simple" paper is here the worse solution. The freedom of the webs, both up and down, at the two sides, will induce quickly an erratic movement of these edges, as soon as the audio power into the coil will be large enough... The resulting distorsion will then be very high ! Thus the constraint, i. e. the form of the webs, and their "termination" (up, down and on the sides) must be studied to avoid this erratic behavior for high input levels.

Thirdly, the whole weight of the complex "coil+webs" have to remain as low as possible, otherwise the impulse response, as well as the frequency response, of the system will be poor. Thus, the intrinsic rigidity have to be obtained with a compromise in mind !...

Hope this helps...

Best.

Last edited by ondesx; 16th February 2018 at 06:02 PM.
  Reply With Quote
Old Yesterday, 09:35 PM   #1197
borzi1024 is offline borzi1024  Hungary
diyAudio Member
 
Join Date: Aug 2016
I play further with ruba.

1. Place damping inside (air filter cloth what I have home)
It has big effect around 1kHz (see close field measurements)

2.Try to paint the membrane, I was looking for "flexible" paint. I found in local shop Body 950 stone chipping protection for cars http://hbbody.com.gr/products/filesU...IP_710_tds.pdf

The application of this material is far from perfect (ugly), because the diaphragm was already assembled and because I'm unexperienced in spray painting.
I was surprised how heavy it is, I almost double the diaphragm weight. (86 g)
I was expecting it kills the highs totally, but surprisingly the effect is not that much for highs.
It sounds less "paper", less shouting, subjectively.

Unfortunately I have no an-echoic chamber for measurement, and since it has dipole radiation the measurement strongly effected with room reflections. (I plan to make "an-echoic" measurements outside in my garden when the weather became better.)

I play with measurement in different positions, and seems as I have less resonation/distortion at lower freqs, I measures closer to theoretical "open baffle" freq response.

I was looking again to Mr. Linkwitz's site.
He was developing many dipole speaker systems.
Unfortunately I not heard any of the system, but there are too many review which tells his systems has extraordinary life-like sound.
Electro-acoustic models

What is the right baffle size, design for ruba?
Equalization to get proper low mid response?
Attached Images
File Type: png Paint_damping.png (148.0 KB, 4 views)
File Type: jpg Paint_internal_damping.jpg (673.0 KB, 5 views)
File Type: jpg Black_paint.jpg (934.7 KB, 5 views)
  Reply With Quote

Reply


A DIY Ribbon Speaker of a different KindHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Ribbon Bookshelf Speaker LineArray Multi-Way 2 6th June 2008 12:38 PM
What kind of laptop to analyze speaker ostie01 Multi-Way 2 27th December 2005 08:18 PM
New Ribbon Speaker Technology - Approach the perfect speaker? cocolino Planars & Exotics 49 16th January 2005 11:12 PM
What kind of speaker design is this? Keith TDI Multi-Way 8 25th March 2002 04:56 AM


New To Site? Need Help?

All times are GMT. The time now is 12:27 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki