DIY Distributed Mode Loudspeaker

[turgid]

A mini-project with results below :

https://www.youtube.com/watch?v=feQltBOw0sI

Hardboard absorbs a lot of sound and is more of a damper, introducing its own amount of distortion and causing the low sensitivity. The speaker works much better with more rigid surfaces like wood. Metal not advisable due to its artificial sound and a more nasal feeling to voice however much brighter and slightly more detailed than wood.

The sample in the video is run mono.

Also called Bending wave loudspeaker or surface speakers. Dayton Audio now manufacturers exciters which use the same principle.

 

[soundnovice]

this is interesting. can you share links which explain their principle and example diy builds.
and your own build details ofcourse!

 

[turgid]

this is interesting. can you share links which explain their principle and example diy builds.
and your own build details ofcourse!

Thanks for your interest dear sir.

There are a couple of companies that use this technology like Gobel hi end epoque reference, Manger audio in their manger driver. also German Physik and MBL albeit with a slightly different and older design. You can check them out for an intro but I will post the pics of my build tomorrow.

My design is far from the last word in precision, it was made for learning and passing time. the design seemed to work great but needs a crossover for any bass response.

 

[turgid]

Here are some pics!

If we modify multiple drivers, we can excite a whole surface area, a rigid one at that, with very low distortion and good sound, much like a line-array would operate. Since the operating principle is by distributing the modes over a larger surface area, the sound stage will be much more engaging than a simple dome speaker configuration.

I am also working on another design which operates on the same principle at this point of time and using normal paper for driving material.

Sick at the moment so if interested, please expect delays.

Regards,

 

[sarith]

I am also working on another design which operates on the same principle at this point of time and using normal paper for driving material.

Sick at the moment so if interested, please expect delays.

Regards,

Nice job. Boston speakers? I was thinking about something like this using wood mica sheet.

 

[soundnovice]

so if i understand correctly, the voice coil is connected to the large surface in place of default cone!? i have not yet understood the underlying principle how this works...given my poor technical knowledge in this regard probably i wont understand! can you explain in brief here how this system works

 

[turgid]

so if i understand correctly, the voice coil is connected to the large surface in place of default cone!? i have not yet understood the underlying principle how this works...given my poor technical knowledge in this regard probably i wont understand! can you explain in brief here how this system works

Technically that's how it should be done but I didn't want to do any irreversible damage that is why I planted the transfer mechanism on the dust cap itself. Yes, the default cone is substituted by larger rigid wood. The wood is thus excited above a certain frequency threshold and hence more drivers will make it easy to excite the wood and produce sound much like a line array.

 

[saheb11123]

Wow!!
This is a great thing.
Will be watching the thread and experiment as it progresses.

 

[Fantastic]

These came out many years ago but didn't succeed in the market . It never beat the really good speakers in performance but seemed to show a lot of promise. One company which promoted it at that time was called NXT . They apparently have a lot of industrial/aeronautic users and the company licenses out the technology.
You can get the small drivers from companies like Parts Express meant to be mounted on glass panels or any other type of panel you choose.

After seeing this post I asked the same question ...'what happened to the technology' and put it up on Google. Here is one link:
Whatever happened to NXT Loudspeakers [Archive] - The Art of Sound Forum

 

[turgid]

Mr fantastic... I am not entirely in agreement with you. NXT was closest to commercially viable design but German companies that started this has made quite a mark, albeit at exorbitant prices. The fact that these speakers have a large driver relative to the listeners head is part of my motivation for initiating this build. While to my knowledge this type of DML was first designed by Katz audio, the reception of that particular model was not the best.
The gobel epoque reference has won some awards at the Munich hi end, so has the MBL 101 and German Physik.
I want to purchase fibre glass and continue this build but unfortunately I will not be able to for a week now.

 

[turgid]

These came out many years ago but didn't succeed in the market . It never beat the really good speakers in performance but seemed to show a lot of promise. One company which promoted it at that time was called NXT . They apparently have a lot of industrial/aeronautic users and the company licenses out the technology.
You can get the small drivers from companies like Parts Express meant to be mounted on glass panels or any other type of panel you choose.

After seeing this post I asked the same question ...'what happened to the technology' and put it up on Google. Here is one link:
Whatever happened to NXT Loudspeakers [Archive] - The Art of Sound Forum

nXT is also convenience based not exactly like the other companies in the industry. Bending waves are definitely better than most dynamic speakers when it comes to stage. The height and width of magnepans for example are ridiculously large in comparison to normal conventional speakers. I actually believe these work better than conventional speakers

 

[Fantastic]

I'm sure you know best. Wish you all the best.

However, have you heard large Magnepans or large electrostatics ? I have.
Maybe you should hear them. Someone around here will surely have one of them.

 

[turgid]

I heard some old Magnepans quite recently. Their stage is humongous. Focal grande is the same too although less cohesive but slightly more detailed.

My models are all half measures. I have a few designs I have not seen around much, I am trying to make a working model of these

Many thanks sir

 

[Fantastic]

You need to remember that all you need to make is an 'enjoyable speaker'.
All a speaker needs to do is to make you enjoy the sound, sometimes even if it's not so technically perfect.
Measurements are only there to help you stay fairly close to the main road ( and don't get lost !). You can always take a branch ! It will still take you where you want to go !

There are no best speakers in the world and never will be ! Everything sounds better or worse in a relative environment. Most sound very good by themselves and give you enjoyment which is why it's there in the first place.

Have fun experimenting. It's the fuel for your mind ! Will keep you young forever !

 

[soundnovice]

Fantastic Fantastic!

 

[soundnovice]

found this on diyaudio community
A Study of DML's as a Full Range Speaker - diyAudio

 

[rmeinke]

Hello all,
There has been much documented about building a DML flat panel speaker over at Audio Circles... this is the largest DML thread on the forums - NXT.......rubbish??....THINK AGAIN!

I best sounding material that is widely available is EXP and thinner plywood. Both have followers based on personal preferences. I've been listening to 1" thick XPS panels and really enjoy them! I have tested and listened to a number of exciters from Parts Express (NXT or licensed technology from them) with excellent results. My current favorite exciter is the Dayton Audio DAEX32U-4 Ultra. Not as reliable as some others but sounds the best on lightweight panel material like XPS with the "skin" sanded off and the front and back treated with a 1:1 mix of water and PVA glue. There are pages and pages of info on the link above.

These panels are especially excellent with live recordings, jazz, acoustic and other small venue/non synthesized recordings.

 

[rmeinke]

Here are some pics!

If we modify multiple drivers, we can excite a whole surface area, a rigid one at that, with very low distortion and good sound, much like a line-array would operate. Since the operating principle is by distributing the modes over a larger surface area, the sound stage will be much more engaging than a simple dome speaker configuration.

I am also working on another design which operates on the same principle at this point of time and using normal paper for driving material.

Sick at the moment so if interested, please expect delays.

Regards,

Hello turgid,
There are some caution to using multiple exciters or drivers used on a single panel. The more exciters added to the panel the more cancellation and destructive interference you will have. This can be modeled with the NXT Design Studio software. With the current high-power handling exciters you can get very good output levels and freq. response from XPS panels ranging from 24"x24" to 2 1/2 feet by 6 feet (tall). The panels are certainly full-range and easily reach down to 40Hz and extension to 20KHz all using a single exciter.

And as you mention, given that the nodes are distributed across the entire panel, it shares the same qualities as a line array. The sound stage is very enveloping and allows the listening to "step into" the recording venue. Very enjoyable.

Kind regards,
Rich

 

[Fantastic]

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

 

[goldyrathore]

There is a lot of DIY info at PIEZO NXT type panel - diyAudio