Very nice panels. I see you are using a frame and a spline, good job. What type of material are you using as the diaphragm?
You can put some type of isolation pads directly under the panel stands to tighten up the sound.
I stumbled across 4mm Twin Wall Polycarbonate glazing panels. I believe the same material is sold for greenhouses. Not sure if it's the best material, but it looked interesting. Seems to work. I have tried to make the speakers 'modular' where it is possible to remove the middle frame holding the diaphram and exciter and replace with an alternate diaphram with exciter. I too am using an adhesive double sided foam (easily removable though) to hold the diaphram to the back frame and a foam weather-shield non adhesive strip on the front frame to hold/damp the front side of the diaphram.
I have never heard a speaker that has such a cohesive, natural sound, when given the room to breath. I realise they have problems, but I wonder if these problems are also due to the recording process as much as the speakers themselves. Vocals can sound odd, but I wonder if that is due to electronic processing as, well recorded, acoustic instruments sound phenominal. I have read of people complaining that instruments can sound too large, but that only occurs with certain recordings, so seems recording based and not speaker based. I believe DML's, from my limited experience, lay the recording process and environment out infront of the listener like no other speaker. Next I will try some DSP with them via JRiver. Lots to play with.
I am also wondering with vocal recordings if these speakers let you hear the actual sound characteristic of the microphone being used, as the peculiarities/variations in vocals vary from recording to recording. Maybe someone could build a studio microphone based on the same DML 'technology'. Might be interesting?
I have never heard a speaker that has such a cohesive, natural sound, when given the room to breath. I realise they have problems, but I wonder if these problems are also due to the recording process as much as the speakers themselves. Vocals can sound odd, but I wonder if that is due to electronic processing as, well recorded, acoustic instruments sound phenominal. I have read of people complaining that instruments can sound too large, but that only occurs with certain recordings, so seems recording based and not speaker based. I believe DML's, from my limited experience, lay the recording process and environment out infront of the listener like no other speaker. Next I will try some DSP with them via JRiver. Lots to play with.
I am also wondering with vocal recordings if these speakers let you hear the actual sound characteristic of the microphone being used, as the peculiarities/variations in vocals vary from recording to recording. Maybe someone could build a studio microphone based on the same DML 'technology'. Might be interesting?
The panel moves in pistonic motion, not the exciter. If I said the exciter becomes pistonic I misspoke.
Reducing panel weight helps the exciter move the panel in pistonic motion. Edge damping with a surround will help support the panel weight to help pistonic motion. At the same time, edge damping fights against pistonic panel motion.
Alternatively, internal damping without a surround keeps the weight in the panel. There's no surround to fight pistonic motion but there's more weight hanging on the exciter motor.
An advantage of edge damping with a surround is less weight on the motor. A disadvantage of edge damping is less energy transferred to the air.
The panel does not move. The exciter moves (vibrates) the panel. Therefore the panels weight has no bearing on a exciters pistonic motion that the exciter didn't already have to begin with.
Reducing panel weight does help the exciter move (vibrate) the panel more freely but it does not make the exciter become more pistonic then it originally was meant to be. Using edge damping as a surround will help hold and support the panels weight in place but it wont increase pistonic motion.
Less energy transferred to the air is a advantage not a disadvantage as the goal is to keep the energy transfer from escaping to the edges and keeping it IN the panel diaphragm. This is one of the many reasons why majority (99.9%) of all conventional cone drivers use a surround made of foam, rubber and or cloth for edge damping. Its no different when it comes to DML/BMR tech.
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DML = vibration
BMR = vibration + pistonic motion
We hear energy that is transferred to air in the form of sound pressure. Transferring energy into a surround doesn't help us. It's an energy loss designers accept to mitigate weaknesses in cone speakers as well as DML panels.
The purpose of damping surrounds on DMLs is not to keep energy in the panel, the purpose is to absorb edge diffraction so it doesn't reflect back into the panel in the form of standing waves. Damping surrounds can pull double duty as weight support, but their primary function is damping edge diffraction. If a designer uses different techniques such as edge geometry (e.g. rounded corners) to control edge diffraction they are better off holding the weight of a panel with string rather than losing energy to a surround. A designer can even support the panel with an exciter attached to a spline.
Here's a link where you can learn more about how DMLs work on Dayton's web site.
Dayton Audio Exciters Buyers Guide
This image from Dayton's web site is always a good one to remember when designing DMLs.
The method you use to dampen your panel (mitigate ringing/resonances) will help you choose how to support your panel - or vice versa. For example, if you use internal damping you might not want to use a surround. It all just depends on how your design fits together as a whole.
The method you use to dampen your panel (mitigate ringing/resonances) will help you choose how to support your panel - or vice versa. For example, if you use internal damping you might not want to use a surround. It all just depends on how your design fits together as a whole.
Attachments
The transducer aka exciter will determine if it has pistonic capabilities not the panel materials weight. All "FULL RANGE", exciters will play at modal modes for the mid to high frequencies but not all full range exciters will have pistonic motion. Only the exciters with high excursion will be pistonic to a degree. Most full range exciters drop off like a rock after 100hz for the mere fact that most exciters are not pistonic like conventional cone speakers.
To pressurize air from a diaphragm it must be focused. Surrounds are use to dampen the edges so the sound energy is not released at the edges instead the sound is pressurized only on the diaphragm itself. Damping stops the energy from being released at the edges and wasted.
Have you ever heard a conventional cone driver WITHOUT its surround on? Well I have and it sounds awful because the energy is being released at its sides instead of being pressurized on the cone area. Without any type of damping at the edges some energy will be released at the edges instead of all the energy being focused on the front or back of the diaphragm.
Using damping does reduce some energy loss in sound levels but the rewards out weigh that slight loss in spl. If the rewards didn't out weight that slight loss of energy then all conventional cone speakers wouldn't use surrounds on there drivers because all surrounds dampen a diaphragm to a degree. Rounding of corners is different from edge dampening. We are not trying to REINVENT the wheel as there is specific basic foundations one must adhere by if you want good sounding loudspeakers.
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Its in plain site as those Dayton images show what I have been saying forever that damping is done on the edges like the surrounds on a conventional cone speaker.
1-3 is used for damping which reduces vibrations.
4-6 is used to "CONTROL", vibrations.
With reference to my post (393) showing the exciters that I am using for experimentation. I have just this evening tried the same exciters hot glued to a couple of ceiling tiles and the results are just extraordinary. I’ve dialled in (by ear) a decent sub to fill in the bottom end was quite taken back by the sound.
How much cutting and sawing and drilling and glueing have I done over recent years constructing speaker boxes of various types only to have them thoroughly put in their place by sticking an exciter to the back of a ceiling tile!
Loads of rewarding fun for such little effort.
Do try these as they have at least one distinct advantage over other exciters in that the metal plate that is for attaching to surfaces can be unscrewed from the motor assembly to allow easier attachment and detachment. It could even be drilled to allow bolts ensuring a tight ‘easy to remove’ bond.
OK, I’m back out to my shed for some listening with a nice organic red from Puglia.
How much cutting and sawing and drilling and glueing have I done over recent years constructing speaker boxes of various types only to have them thoroughly put in their place by sticking an exciter to the back of a ceiling tile!
Loads of rewarding fun for such little effort.
Do try these as they have at least one distinct advantage over other exciters in that the metal plate that is for attaching to surfaces can be unscrewed from the motor assembly to allow easier attachment and detachment. It could even be drilled to allow bolts ensuring a tight ‘easy to remove’ bond.
OK, I’m back out to my shed for some listening with a nice organic red from Puglia.
Having finished the bottle of red from Puglia and after a ‘lights out’ listening session with Yello, Melody Gardot and Chris Jones I can conclude that the sound coming from a pair of old ceiling tiles is really quite remarkable. I am hearing nuances in recordings that I have not noticed before.
Taking advice from the YouTube video of the ‘Worlds Best Speaker’ I shall try and fettle and finesse the ‘ceiling tiles’ for a more finished look and see where this can go.
To anyone who has not tried DML’s I urge you to try as they will definitely challenge your entire outlook about what loudspeakers are.
Taking advice from the YouTube video of the ‘Worlds Best Speaker’ I shall try and fettle and finesse the ‘ceiling tiles’ for a more finished look and see where this can go.
To anyone who has not tried DML’s I urge you to try as they will definitely challenge your entire outlook about what loudspeakers are.
I agree completely. I can’t help but think loudspeaker design took a wrong turn very early on. I applaud all the development effort and the technology behind conventional speakers today is impressive, but my simple cheap panels are entirely competitive with my electrostatics and in some areas with sharp transients, e.g. percussion, they are much better.
Jerryo,
Very intereresting! I know this may be difficult, but do you know what these ceiling tiles are? There are many different types of ceiling tiles. I know because I make them for a living! In fact my company has some DML patents, and commercialized speakers with DML technology in the early 2000's but these used composite panels different from conventional tiles, but covered them to make them look like tiles.
Eric
