DIY Distributed Mode Loudspeaker

Fantastic said:
After Turgid started this thread it reignited my interest in this.
So I've been occasionally looking at the developments on the Net. Apart from the very exotic brands I found other companies are still interested in it.
Turgid is right, the concept isn't really lost in the background. But yes, it certainly is a great application to experiment with !

I found this company which supplies panels for home use. But there isn't too much info ( or pictures on how they implement it ). purSonic Flat panel loudspeakers | Soundboards
There must be many more.

Has anyone actually heard the Monsoon computer speakers that worked on this principle ? People said it was great and just as I was trying to buy them ( a few years ago ) they disappeared ! Wonder why.
I think Toshiba or Yamaha also displayed a prototype but never heard of it after their web presentation a while ago.
Here is a Masters Thesis that could be informative.
http://publications.lib.chalmers.se/records/fulltext/61709.pdf

Look at what this guy did ! You can see that he experiments with everything audio ! :)

http://i82.photobucket.com/albums/j263/CLS_photos/Audio/DML Trial/DSCF6859_zpse9fa5685.jpg

http://i82.photobucket.com/albums/j263/CLS_photos/Audio/DML Trial/DSCF6864s_zpsbc5cf5a8.jpg
Click to expand...

Hello Fantastic!
CLS did indeed do much experimentation and most of the work can be found in the mother of all DML threats I posted earlier.

Cheers!
 
Hello people,

This thread did catch on. I was away job-hunting.

Yes Mr. Rich, I am aware of the destructive waves if more than a single driver is used but companies like Amina and Katz Audio uses diagonal and offset from center array structure but I am not aware of its benefits or technicalities.

I was a few steps away from visiting the Munich Hi-end 2015 but my school dragged me down since Gobel hi-end is what sparked my interest in these.

I have lost my interest in this project now back to my favs - planar mags. <3

Mr. Fantastic,

I saw the link and its amazing! But that just reminds me of a magnified rubanoide structure. Rubanoides are some of the best investment of your time in DIY. They fill in all the boxes of a DML and have better frequency extension~ nearly full range . The only problem is the diaphragm material to be used since paper changes tension with humidity changes.


P.S> my reason for leaving this project is the amount of raw driver buying you need to do and its not worth without precision engineering. As a last step, a month ago I used both the drivers and attached it to my bathroom door 150 cm apart along the same axis but 5 cm off center and the sound was way way better than in the video. I could hear resonances in the door from its hollowness but frequency extension improved so did sensitivity.

Hardboard is fibrous and absorbs sound, but never complain about free stuff ;)
 
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Hello Turgid! Sorry to hear you are moving on from the DML magic panels.. the fun was just about to begin!! :)

I've been listening to DML panels for some time now and enjoy them. I purchased a pair of KEF Q500s and think they are an excellent speaker for such a small change... KEF technology is amazing and a tribute to what a large commercial company can do when it brings it size and technology to bare. I really enjoy them greatly but the DML flat panels have a certain magic that keeps my interest and I don't want to turn them off even after a long, late night listening session.

The soundscape is amazing... super large and wide... room enveloping. They are also sensitive and easy to drive with even a low power class D amp board.

If you have not built a set, you really owe it to yourself to listen to them.

I know shipping is expensive from suppliers like Parts Express but I would be happy to help by shipping you a set or 2 for the simple cost of shipping. Might be able to save some bucks that way.

Think you will be real happy with the results!
 
rmeinke said:
Hello Turgid! Sorry to hear you are moving on from the DML magic panels.. the fun was just about to begin!! :)

I've been listening to DML panels for some time now and enjoy them. I purchased a pair of KEF Q500s and think they are an excellent speaker for such a small change... KEF technology is amazing and a tribute to what a large commercial company can do when it brings it size and technology to bare. I really enjoy them greatly but the DML flat panels have a certain magic that keeps my interest and I don't want to turn them off even after a long, late night listening session.

The soundscape is amazing... super large and wide... room enveloping. They are also sensitive and easy to drive with even a low power class D amp board.

If you have not built a set, you really owe it to yourself to listen to them.

I know shipping is expensive from suppliers like Parts Express but I would be happy to help by shipping you a set or 2 for the simple cost of shipping. Might be able to save some bucks that way.

Think you will be real happy with the results!
Click to expand...

Hi there dear sir,

Hope all is well with you. Thank you but I have been interested in planar ribbons more than DMLs for a long time now.

Dayton Audio has been manufacturing exciters that is easy to DIY onto wood for a bending wave effect and should give one the same effect you are talking about. DAC is a distributor of such drivers here in Cochin.

Anyway I am interested in Ribbons more and have a few ideas running but to show you why I am interested in ribbons take a look for yourself. This is my home made ribbon that does an amazing job with speed and treble timbre and definition. The sensitivity is good too. Definitely for the lower frequencies I need to X-over with a more conventional driver but here you go.

https://www.youtube.com/watch?v=WE6VC9Srcjw


Cheers,
 
Hello,

Just a note....I have been fighting with myself whether to post this design before trying or after. Those of us who have interest in things other than off the shelf drivers are few and far in between. I live in an apartment so working on these things is quite a hassle and time consuming. My room is full of screws, wood and things I have bought and used/not used. I often sleep in another room because I am afraid of my own room like last week I found a screw in my leg and was bleeding unaware! Every time my parents come up to Bangalore, there are words of wrath about my conduct and misdemeanor all thanks to DIY!.. :lol: .. I would really like to sell my bed and make my room a garage just for DIY but I guess the sofa is not all that comfortable... Anyway this is a Bending wave/DML design I have been thinking about - 2.1 for home use

Reason is that 2 channels of my Bose Acoustimass 10 system are not working. The sub is working as intended. The wiring is under the tiles and therefore repair is a long lost dream. Also never been a fan of 5.1

1. Bass and Mid panel - 80 cm by 40 cm by 5mm~10mm XPS/EPS foam (yet to find a dealer) working from 150 Hz to 2500 Hz. - Magnets used will be 40by20by10mm. D-S = 1 mm
2. Tweeter - 42 cm by 8 cm wide ( A3 paper cut to requirement ) - 2500 Hz & up. These will be omni-directional since its a cylindrical structure. I am not sure if it will reach 20 Khz but its worth a try. Magnets will be 30by20by5mm. D-S = 1~1.5mm
3. Bose sub playing 150 Hz and down.

First order cross over. The design is from ground up so there is no use of exciters, which is the norm with DMLs. The blue borders imply dampening with foam tape. I am winding my own VC across the foam and paper diaphragm respectively for 4 ohms. 32 AWG for Bass & Mid panel. Looking for an Aluminium magnet wire dealer who has 30 AWG for the tweeter, else will use the 32 AWG copper for the tweeter too although this is quite heavy. Refer attachment, hope my poor Sketchup skills make sense ... The second pic is the rear with yellow implying an under hung VC. Shades of red (pink and maroon) = north pole, shades of grey = south pole.

This is all a plan and nothing except point one has been implemented, although it was a few weeks ago and I have a habit of leaving things half way. There can be changes over and again from this per SPL and what not... god I might even not do it ...but any advice is welcome except that I should use exciters.

Cheers,
 

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Fantastic said:
Has anyone actually heard the Monsoon computer speakers that worked on this principle ? People said it was great and just as I was trying to buy them ( a few years ago ) they disappeared ! Wonder why.
Click to expand...

Late reply but the Monsoon speakers are Planar Magnetic speakers to my knowledge, Push-pull ones at that.
 
turgid said:
Bending wave speakers using 5 mm Foam board. The VC is handglued with 32 AWG - around 1000 cm which theoretically will give over 4 ohms. With a conventional exciter, these boards will be pretty amazing. They are closed cell foam, really light and pretty strong.

https://www.youtube.com/watch?v=tsdmFCHEJeo
Click to expand...

The Youtube clip is not very informative. It does show that the system produces sound but you can never hope for the viewer to know how it really sounds.
You can use the video to show details of what has been done like showing the rear and how the unit is being driven etc. Looking at the blank front doesn't give any information at all.
 
Maybe you could use an elastic band or rubber suspension along the edges. I've seen someone doing that . Will improve the low end. If you don't want much low end you could reduce the panel size ? Bass may come from a regular driver ?
I feel it might be easier to focus on the higher frequencies and assist it with a regular driver for the lower end. Later you can widen the bandwidth. That way you might save some time getting the panel to work acceptably.
 
Fantastic said:
The Youtube clip is not very informative. It does show that the system produces sound but you can never hope for the viewer to know how it really sounds.
You can use the video to show details of what has been done like showing the rear and how the unit is being driven etc. Looking at the blank front doesn't give any information at all.
Click to expand...

I have given the details of the construction in my earlier post with the Sketch up design, which you may refer. Its just Fleming's left hand rule in action. :p

Fantastic said:
Maybe you could use an elastic band or rubber suspension along the edges. I've seen someone doing that . Will improve the low end. If you don't want much low end you could reduce the panel size ? Bass may come from a regular driver ?
I feel it might be easier to focus on the higher frequencies and assist it with a regular driver for the lower end. Later you can widen the bandwidth. That way you might save some time getting the panel to work acceptably.
Click to expand...


Thanks for the suggestions Fantastic.

With such a driver, it is generally tougher to get good HF extension and easier to get acceptable bass. Infact I am getting some bass once I reduced the D-s. I have recorded some classical music with the lower D-s and there is more SPL.
Yes I need to work on better suspension, if you see there are two cuts in the upper and lower centres which is tape doing suspension.

Again an uninformative video :o , but this is what I can do best at the moment.

https://www.youtube.com/watch?v=prGd_tPQ8BY
 
Noticing some of the benefits of the last prototype, I decided to try a smaller version, but with increased magnetic field by 1. gluing the magnets instead of putting them on steel and consequently causing field saturation, 2. spacing them closer and 3. by having more conducting strands per unit area.

The result is a very capable speaker. It goes quite loud. I am guessing 85+ dB!! :yahoo: The sad part is the video I uploaded on youtube has been muted due to copyright claim! It will have to wait till tomorrow for another video.

@Fantastic - I tried your suggestion of rubber band but can't quite notice the difference may be because its the ordinary one and not the thick fat one?

Thx,
 
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