Hello Jaxboy
Don't worry, I show my designs as examples, not as a unique solution.
Steve is right. This is not a canvas but a DML made with a corrugated polypropylene. For more detail see #10742 and before #10724, #10187. So no need of pad (I tested a pad on it, it doesn't work).
Following your example when I started with DML, I built a pair of canvas which has a balsa pad and now a spine. I will try to think to make a picture (they are in another location). The assembly of the spine is simpler with just a double side tape at the rear of the exciter. So yes, it is possible to make it more simple as you mentioned.
The reasons of the one in the previous post (just above) were (in the plywood membrane version) to have them as flat as possible and to have the possibility to remove quite easily the the exciter.
Christian
Thanks for clearing that up. Which material do you think sounds better? Also, how big are your examples?
Hello Jaxboy
For the dimensions or information about panels (not only mine!) shared in this thread, you can refer to the history file I posted here. The link : DML history file and other documents of my "DML repository".
Direct link to the history file AStudyOfDMLsAsAFullRangeSpeaker.pdf. Last update was about one year ago. Time flies!
- 3mm poplar plywood 120x42cm. Very good. Used in wide range even if the LF extension is too short. HF ok. Very living; My favorit
- canvas panel 33x41cm. Good. Excellent LF extension for the size. Some bumps that would need EQ.
- polypropylene : panel (frame) is 43 x 55cm, membrane 35.5 x 46cm with a rounded contour. Not yet in the history file. OK above about 250Hz (it was the target). Short in HF with a limitation around 9kHz (I added a tweeter). First intention was to have ambiance music with friends. It meets more than this target. I haven't listen to it enough and not in the proper conditions to say more. I think this membrane is more dedicated to application where some resistance against water or humidity is required. The estimation of efficiency is 93dB (TBC). So a good candidate of a BBQ party DML.
Homeswinghome,
Thanks for the reply and the link to the repository. I put it in my "favorites" for easy reference. I have only built the canvas ones, as I have built several box speakers from XRK971's designs for foamboard, which sound very good. I have a small room to put my audio in, so another speaker of any type is out of the question, due to space.
Thanks for the reply and the link to the repository. I put it in my "favorites" for easy reference. I have only built the canvas ones, as I have built several box speakers from XRK971's designs for foamboard, which sound very good. I have a small room to put my audio in, so another speaker of any type is out of the question, due to space.
80W 4/8ohm 100MM Full Range Vibro Speaker Audio Portable Loudspeaker Vibration Anti-neighbor Resonance Bass Sound Exciter - AliExpress
DML subwoofer/helper woofer anyone?
DML subwoofer/helper woofer anyone?
If the reminder in my agenda works well (I just got a new phone!), I will send you pictures of my canvas next week-end.
Christian
Hello Karlsonate,80W 4/8ohm 100MM Full Range Vibro Speaker Audio Portable Loudspeaker Vibration Anti-neighbor Resonance Bass Sound Exciter - AliExpress
DML subwoofer/helper woofer anyone?
With the advanced search tool of the forum, input the keyword "infraflex", posted "homeswinghome"
Not tested. I am curious of the results. The engine is not an exciter but a woofer to get elongation (needed in bass). According to the pages (in french) about it, the users seem happy. It is basicaly a 0.7 to 1m round/square DML. I have 2 technical doubts :
- there is nothing to make a basic calculation/choice, so a risk of trial/error loops.
- as all the DML, there is a front and a rear wave in opposition of phase (dipole) which while reading posts about open baffles might not be the best choice. The best choice being a monopole in a close box.
Me too. I switched from android to Apple, so a fairly steep learning curve in some respects. The passing over of my data did not include the 5.6 GB of music on the android. Bummer! I've got to download all my apps again, too.
Christian,
I've taken a look at Infraflex, it's mighty interesting, and at the same time, mysterious with some of the design choices (presumably due to trial & error, like you said). I'm purely going by the pictures shown in this website: Infraflex: an attempt at synthesis (forum-hifi.fr) so please let me know if any changes have been made since then.
1. The way the speaker works with the polystyrene. It seems they've fashioned a (plastic) cap to transmit the vibration from the coil. The cap seems small and makes contact with only the panel center, so I wonder if it can provide optimal coverage for energy transmission. In comparison, I look to the Japanese, in particular, Sony APM drivers and observe how they did it. Here's the link to internals of a Sony APM-33W woofer. You can see that a special bracket is placed at the coil, from which 4 metal (aluminum?) legs adhere into the diaphragm, approx. in 4 directions. I assume it's not only a way to distribute energy evenly but also to combat resonance modes in a square diaphragm. Can the same method be used for Infraflex?
2. How the polystyrene panel "stays" in the box. Is it held by some sort of clamp or simply glued at the edges? Unfortunately, the available pictures are too blurry for me to know.
I don't follow very often what happens on this topic. I took notes about it not really more. I will see when the time of decision for a solution for the bass will come.
In the Infraflex, the exciter is a "disassembled" woofer. the membrane is removed. So as the basket (frame) of the woofer is kept, to fill the gap, the distance in the woofer axis direction, between the membrane and the voice coil a part is added. You can see in the right side of the picture below where the infraflex is shown without membrane. You can see also the woofer frame. This part was made by reusing the plastic pot in which cream or yogurt is sold. I read somewhere some DIYer fill it with expended foam (polyurethane). So the membrane is not driven by legs as in the Sony example but by a cylinder with a small angle that extends the voice coil.
The polystyrene part is square at about the dimension of the finished infraflex (the red square shape below). The membrane is glued in sandwich between 2 square pieces of "wood" having each the circular opening. So the EPS is fully clamped. The left view is the infraflex finished. In the right one, it is before having the membrane and the outer face part.
I have in my wish list to test it. This design has an incredible advantage to offer a huge emitting surface in final volume compatible with a large room. A 1m side perhaps too big for me but 07 to 0.8m might be possible.
Attachments
Thank you for the video.
The NS 20 family was already shown here. There are 2 additional characteristics for this design:
- a cone loudspeaker working partially in parallel with the "elephant ear" loudspeaker
- a tweeter
The elephant ear loudspeaker had a limitation in HF
The interesting questions are:
- Why did Yamaha stop this way of design ?
- Is a dipole speaker the best choice for bass compare to other radiation diagrams (monopole, cardioid?)?
I just ran across this article again and though some might be interested. It provides a good basic history of folat panel speakers and the references are pretty good sources too.
Eric
https://www.aes.org/tmpFiles/elib/20230919/21014.pdf
Eric
https://www.aes.org/tmpFiles/elib/20230919/21014.pdf
Has anyone here tried this... running cone drivers for direct sound along with DML's for ambience/holographic/spaciousness ? I tried it last week and I can't see me going in any other direction...... at least not until the next new shinny (old) thing comes along
So far.. I like it with the DML panels edge on, meaning the edge of the panel is facing the Listening Position, the face of the panel is directed at the walls.
I got the idea from this thread at ASR, the thread starter is a bit cryptic in his wording so someone deciphered it in this post.
https://www.audiosciencereview.com/...aveguided-speaker-combined.27988/#post-969627
I'm thinking that the "loudness" of what follows the initial Impulse Response is what gives a DML panel it's ambience/holographic/spaciousness ?
Here are 3 Impulse responses to compare a 2 way cone/dome speaker and 2 DML panels. The Polystyrene lid comes from the polystyrene box the local fresh fish supplier gets their fish delivered in. It seems quite dense.
Hi Dean,
The link in that post does not describe how the panel is wired...
Is it a mono mix of the left/right? Is it a centre channel mix? Or is it a left-minus-right mix?
If I had to run a system like that, my preference would be for two DML panels placed flat-on 1 or 2 metres behind the listening position, one wired left-minus-right, and the other right-minus-left. This should give you maximum ambience without running a full-on surround-sound system.
Theoretically the only difference between two cone speakers wired like this, one-channel-minus-the other, would be their phasing, the one being 180° out of phase with the other one. But DMLs, producing a diffuse wave-front, the phasing is of almost zero consequence, and what this setup might produce is a more diffuse, ambient sound-stage behind the listening position with the DML panels disappearing from the ear, leaving only the ambient sound.
But if you really want to try the system described in that link, then it might be better to run two DML panels edge-on, one behind each box speaker, connected directly to each box either in series or parallel depending on the final load impedances and amplifier capability.
Good luck.
I don't think Yamaha ever made a DML speaker. Just because it has a large, ear-shaped polystyrene surface, does not mean it's working on DML principles.
To prevent the cones bending, 'ancient' polystyrene speakers were either truncated cones or they were made very thick or they were sandwiched in foil, and all of this is exactly at odds with DML principles.
Tectonic manufacture touring grade PA panels. That weigh far too much. And that are very expensive.
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Hello Eric
Thank you. High density paper! I have found in it the basis of the theoretical approach we have tried to follow up to now (including the early tentative of simulation). It seems it goes further for example with concepts of modal overlap and the transition frequency.
A very good basis to enter in the DML world by academic papers (the "north route"?, in this image is the "south route" is the experimental approach, it isn't so easy neither!)
Christian