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

A Study of DML's as a Full Range Speaker
A Study of DML's as a Full Range Speaker
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 17th April 2015, 07:00 PM   #121
RGood is offline RGood  United States
diyAudio Member
 
Join Date: Aug 2014
Location: Midcontinent U.S.
Soldermizer,

First, please pardon the misspelling in my previous post. I haven't looked back at Li's abstract of conclusions, but he does list the DML efficiency as 0.92% and that of his conventional loudspeaker as 1.81%. He also indicates the overall sensitivity of the DML as about 7.5dB less than the conventional speaker, so I don't think there's really a discrepancy, at least in his test results.

I do think he used a very small panel, about 17 x 20 cm, and all his trials were with one panel material and one exciter position. You may learn more practical results about this technology with your experiments than Li did.
  Reply With Quote
Old 17th April 2015, 09:34 PM   #122
Soldermizer is offline Soldermizer  United States
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
"- Exciters are slightly less efficient than conventional loudspeakers. As a very rough guideline, expect to replace one speaker with two exciters in retrofit applications."
Buyers Guide - Exciters

OK either I'm wrong or somebody else said that DML is more efficient or both!

"Practical?" Me????

Mentioned earlier in this thread and possibly of use in tuning or just making a mess! Is there any point in looking at the resonances (Chladni or drum head modes) of a panel? All we need is a sine generator, some sand or flour (send the wife away for the afternoon first!) ... and blast the membrane. Having not done this at all, I am just speculating but even if we identify the modes and nodes, does this help in placing the exciters? The mere act of adding mass or damping to the panel changes everything, doesn't? Sort of like Heisenberg's uncertainty principle applied to audio tinkering.
__________________
The world awaits the album photo of the artist standing before his Steinway and the album to be titled Fully Erect Pianist

Last edited by Soldermizer; 17th April 2015 at 09:45 PM.
  Reply With Quote
Old 18th April 2015, 04:54 PM   #123
Soldermizer is offline Soldermizer  United States
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
Click the image to open in full size.Click the image to open in full size.
Panels are about 48x45 Inches. Massive bass boost really helps. Also removed two mount points per driver so that panel flaps in the breeze better They have some "unauthorised" noises to troubleshoot. Fun!
__________________
The world awaits the album photo of the artist standing before his Steinway and the album to be titled Fully Erect Pianist
  Reply With Quote
Old 19th April 2015, 01:39 AM   #124
CLS is offline CLS  Taiwan
diyAudio Member
 
Join Date: Jun 2005
Location: Taiwan
It doesn't look right on the fixing between driver and panel.

Try lengthening the timber and using soft material to couple the panel. Keep the mounting points away from one another. Like the one on the right in my sketch. The driver itself and the panel should be supported separately.

Click the image to open in full size.

Or, if your driver can support itself, then ditch the wood blocks between frame and panel, and the timber. Then suspend the whole thing by other fixing points on the panel itself. By this, you support the panel only, and let the driver 'float' on it (by its own suspension).

And, your panels looks very near the wall and not much space around them. If they have to be that way, put some sound absorbing material between panels and wall to reduce reflections.

Last edited by CLS; 19th April 2015 at 01:45 AM.
  Reply With Quote
Old 19th April 2015, 05:43 AM   #125
Soldermizer is offline Soldermizer  United States
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
CLS: Thank you for the suggestion. I will do the easiest first: remove hard (wooden) feet of speaker and instead find a softer means of connecting the timber at its far ends. I am leery of free-floating the panel ( = only attached at speaker cones). I had voice coil alignment issues when I tried that with the smaller coroplast panels. A conventional speaker's suspension is tuned to support a lightweight cone, not cone + 16 square feet of foam board I guess extra foam board qualifies as soft material for the new stand-offs.
__________________
The world awaits the album photo of the artist standing before his Steinway and the album to be titled Fully Erect Pianist
  Reply With Quote
Old 19th April 2015, 03:36 PM   #126
Soldermizer is offline Soldermizer  United States
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
CLS, thank you, I have done as you suggested (removed the wood spacers at speakers and have "soft" spacers (foam board) closer to ends of timber piece.

No doubt you are correct to suggest a panel is better not against or near a wall. However, in my current room (it is small) as hung is probably the best place. Also, if the DML is bipolar or bipolar-like, the backwave should not be as destructive as a dipole?

There is much better bass. EQ is constantly being tweaked, of course. I seem to have peaks at 300-400 Hz and also around 2.5K. Right now, EQ-ed flattish but letting the highs roll off naturally. Sounds very good. With very bassy stuff (electronic, trance etc.) there are still some buzzing issues to hunt down. Other than that, I've heard no distortion even driving them quite hard. I know the science behind the DML is quite complex, but I am amazed the possibilities driver + adhesive + panel offers. Hell, I might even try a legitimate exciter someday

I'm surprised there hasn't been more experimentation with DMLs by hobbyists. It doesn't get much easier than this and no box or wood shop required.

Xrk971: you will be happy to know that I bought a few dozen sticks of hot glue at a yard sale yesterday, "just in case." You probably would have bought the entire stock
__________________
The world awaits the album photo of the artist standing before his Steinway and the album to be titled Fully Erect Pianist

Last edited by Soldermizer; 19th April 2015 at 03:40 PM.
  Reply With Quote
Old 19th April 2015, 08:53 PM   #127
Soldermizer is offline Soldermizer  United States
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
This is just a tangent, but during my dissection of failed drivers, I have seen just how fine the wire on a voice coil is (on a Pioneer/Bose CTS type 4 1/2 driver.) It is very fine wire, what 30, 40 gauge? And people are worried about the quality of their "interconnects" ... leaving aside the high prices some people pay for their "audio jewelry", isn't the current-limiting factor in a speaker the voice coil winding? Granted, this is not a high power subwoofer but isn't theirs still thin wire? So why do purists need cables that carry enough power to light the neighborhood
__________________
The world awaits the album photo of the artist standing before his Steinway and the album to be titled Fully Erect Pianist
  Reply With Quote
Old 20th April 2015, 12:41 AM   #128
mexican is offline mexican  Mexico
diyAudio Member
 
Join Date: Dec 2014
Location: Chihuahua
Audio Myths !

Myth: Using audiophile speaker cables improves the sound, compared to an equally heavy gauge of normal electrical wire.

Dispelling Popular Audio Myths
  Reply With Quote
Old 20th April 2015, 12:53 AM   #129
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
A Study of DML's as a Full Range Speaker
Quote:
Originally Posted by CLS View Post
It doesn't look right on the fixing between driver and panel.

Try lengthening the timber and using soft material to couple the panel. Keep the mounting points away from one another. Like the one on the right in my sketch. The driver itself and the panel should be supported separately.

Click the image to open in full size.

Or, if your driver can support itself, then ditch the wood blocks between frame and panel, and the timber. Then suspend the whole thing by other fixing points on the panel itself. By this, you support the panel only, and let the driver 'float' on it (by its own suspension).

And, your panels looks very near the wall and not much space around them. If they have to be that way, put some sound absorbing material between panels and wall to reduce reflections.
Thanks for the explanations CLS. These are beautiful diagrams. Did you draw these? You should write a textbook on DML's.

Thanks for keeping this thread going. I have been a bit busy with other projects to do any more "studying" on DML's
  Reply With Quote
Old 20th April 2015, 02:13 AM   #130
CLS is offline CLS  Taiwan
diyAudio Member
 
Join Date: Jun 2005
Location: Taiwan
It's just drawn by MS powerpoint and saved as .png file. I'm glad you find it useful.

As to the positioning of the panel in room, even though it's almost omni, you'll find the location and orientation still matter.

The panel is very light. It can be easily affected by the reflections (by the wall). It'd be better to keep the surrounding as open as possible. Or avoid parallel to the wall, and avoid trapped/restricted space formed by the panel and walls as you can. If being close to the wall is unavoidable, some damping material behind the panel can be helpful.

Last edited by CLS; 20th April 2015 at 02:22 AM.
  Reply With Quote

Reply


A Study of DML's as a Full Range SpeakerHide 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
Full Range Voice Range single speaker and enclosure loninappleton Full Range 23 9th May 2014 12:14 AM
Proposal for a full range speaker radio Full Range 20 23rd April 2014 06:03 PM
Design Study: Full Range Line Array Dumbledog Multi-Way 5 27th October 2013 01:45 PM
Full range speaker package. perceptionchanges Swap Meet 1 15th July 2013 04:08 AM
Full range active speaker zebra100 Full Range 10 24th August 2009 12:28 PM


New To Site? Need Help?

All times are GMT. The time now is 07:41 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki