my 2 cents:
In techtalk we have Unbiased a seasoned plat panel builder wich says this:
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What is the proper or ideal exciter placement on a panel? When you look at P.E. exciter placement they use the 2/5 3/5 placement to off set the build up of standing waves. You can read up on there reasoning for using those placements in the P.E. buyers guide to exciters.
IMO those are not ideal placements. The ideal placement when using a single exciter per panel is dab smack in the middle/center of the panel. Has anyone ever seen a conventional cone driver with its voice coil off center from the diaphragm? NO right? DML's are similar to conventional cone drivers then most people realize as we are not trying to reinvent the wheel here. When any transducer is off center it will be less coherent. The most coherent sound is when the transducer is placed smack dab in the middle/center of the panel diaphragm.
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I have to concur with him that deadcenter is the best position. Also with FR analyses i could not find a better position.My explination is that if you imagine you get the longest sinewave (lowest frequency) on the diagonal of the panel when in the middle of it, and because you have 2 diagonals of the same lenght the sound sounds even!
. IF you want to add another exciter then i found a "new "position" that i call the 1/3 rule.
This i found moving a second exciter al over the panel , and the fullest sound i got when reaching the 1/3 position from both sides. This is also a place on the diagonal of the panel!!, again to reach the fullest sound.
A second exciter is not advised because of phase problems with the other transducer wich is in the middle. Go figure...
Hans
In techtalk we have Unbiased a seasoned plat panel builder wich says this:
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What is the proper or ideal exciter placement on a panel? When you look at P.E. exciter placement they use the 2/5 3/5 placement to off set the build up of standing waves. You can read up on there reasoning for using those placements in the P.E. buyers guide to exciters.
IMO those are not ideal placements. The ideal placement when using a single exciter per panel is dab smack in the middle/center of the panel. Has anyone ever seen a conventional cone driver with its voice coil off center from the diaphragm? NO right? DML's are similar to conventional cone drivers then most people realize as we are not trying to reinvent the wheel here. When any transducer is off center it will be less coherent. The most coherent sound is when the transducer is placed smack dab in the middle/center of the panel diaphragm.
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I have to concur with him that deadcenter is the best position. Also with FR analyses i could not find a better position.My explination is that if you imagine you get the longest sinewave (lowest frequency) on the diagonal of the panel when in the middle of it, and because you have 2 diagonals of the same lenght the sound sounds even!
. IF you want to add another exciter then i found a "new "position" that i call the 1/3 rule.This i found moving a second exciter al over the panel , and the fullest sound i got when reaching the 1/3 position from both sides. This is also a place on the diagonal of the panel
!!, again to reach the fullest sound.A second exciter is not advised because of phase problems with the other transducer wich is in the middle. Go figure...
Hans
multiple exciters placing criteria
Many thanks to all of you for your contributions, they helped me a lot to shed a bit of light over this controversial topic.
When I read the monacor's guide I had already placed the first out of two exciters on the panel. I did take for granted that the position for the first one would have not at any rate to be changed. Anyway, before placing the second exciter I read your replies. I ended up placing the second exciter close to the other exciter but closer to the center, differently from what dayton's guide pictures suggest.
They are placed almost on the diagonal of the panel.
Before the incident happened I was very happy with the sound of my single-exciter panels but now with two exciters per panel I've got no doubts the sound got even better.
There were some sounds, like the electric guitar distortion for which I wasn't very satisfied but now they sound very well. Panels now are able to play a more bodied sound, also basses are richer. I'm trying to figure out whether this improvement is related to the only placement of a second exciter or it is also because of the increasing of impedance to 8ohms. Anyway really really happy with this new setup.
my 2 cents:
In techtalk we have Unbiased a seasoned plat panel builder wich says this:
---------------------------------------------------------------------------------
What is the proper or ideal exciter placement on a panel? When you look at P.E. exciter placement they use the 2/5 3/5 placement to off set the build up of standing waves. You can read up on there reasoning for using those placements in the P.E. buyers guide to exciters.
IMO those are not ideal placements. The ideal placement when using a single exciter per panel is dab smack in the middle/center of the panel. Has anyone ever seen a conventional cone driver with its voice coil off center from the diaphragm? NO right? DML's are similar to conventional cone drivers then most people realize as we are not trying to reinvent the wheel here. When any transducer is off center it will be less coherent. The most coherent sound is when the transducer is placed smack dab in the middle/center of the panel diaphragm.
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I have to concur with him that deadcenter is the best position. Also with FR analyses i could not find a better position.My explination is that if you imagine you get the longest sinewave (lowest frequency) on the diagonal of the panel when in the middle of it, and because you have 2 diagonals of the same lenght the sound sounds even!
This i found moving a second exciter al over the panel , and the fullest sound i got when reaching the 1/3 position from both sides. This is also a place on the diagonal of the panel
A second exciter is not advised because of phase problems with the other transducer wich is in the middle. Go figure...
Hans
Many thanks to all of you for your contributions, they helped me a lot to shed a bit of light over this controversial topic.
When I read the monacor's guide I had already placed the first out of two exciters on the panel. I did take for granted that the position for the first one would have not at any rate to be changed. Anyway, before placing the second exciter I read your replies. I ended up placing the second exciter close to the other exciter but closer to the center, differently from what dayton's guide pictures suggest.
They are placed almost on the diagonal of the panel.
Before the incident happened I was very happy with the sound of my single-exciter panels but now with two exciters per panel I've got no doubts the sound got even better.
There were some sounds, like the electric guitar distortion for which I wasn't very satisfied but now they sound very well. Panels now are able to play a more bodied sound, also basses are richer. I'm trying to figure out whether this improvement is related to the only placement of a second exciter or it is also because of the increasing of impedance to 8ohms. Anyway really really happy with this new setup.
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No, they are not, the operating principle is very different. Conventional cone driver try to stay pistonic all over the membrane at all frequencies, on the contrary the DML not. Maybe for low frequencies the center position bring the loudest signal, but for all other frequencies across the midrange that is certainly not the best position.
Well, this is another project that I've finally been able to get around to!
So this became a fun family project, where my daughter offered to paint the canvases with acrylic paint. We sealed it with Gesso, and then she went to work with her designs.
I noted in the thread that 'drum tight' was ideal, so I jammed sticks in between the frame and the canvas, and made sure that both were 'tuned' the same.
I also noted that they sounded best, I think, 6-7 inches from the wall. Initially, I had them mounting on picture hooks, and as one can imagine they sounded a bit strange, so fortunately for me my wife let me get a pair of 6"x8" shelf brackets that I could hang them from. In this case, 6" still wasn't right, but flipping the bracket to allow the speaker to hang 8" from the wall gave the best response.
They're perfect for a living room. Great voice intelligibility, and Bass that makes you think there's a sub tucked away somewhere. I'm using one of the Lepai LP2020A (if I remember correctly) amplifiers, so there's nothing special driving them. I'd highly recommend these for a listening room, and the WAF is very high...to the point that, dare I say, my wife was excited!
The only place in the build I used silicone was for mounting the wooden disc to the centre of the canvas. I'd been working on another speaker project, and so had a hot glue gun to hand. I used two layers of craft sticks on the back to brace the exciter, and added a little semi-triangular brace between them and the frame.
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It's great to see someone playin' with one of my brain farts..
I haven't been doing much lately with DML's. I have a few more designs in thought and plan to get on 'um someday. I've been converting ElCheepo Shower Radio/Bluetooth units into small single speaker units (Mounting them to Bookshelf Speakers) and expanding my knowledge in lithium batteries. It's all fun, right?
I did build a set of DML's using the Polyester canvas (8"x8") with the same wooden disc that I used in most of my other builds and found the bass response was improved. I damped the canvas with circles of hot glue from around the center to the outer edges and this did improve the overall sound. When I get around to it, I will get a pic up.. (It's midnite..)
I haven't been doing much lately with DML's. I have a few more designs in thought and plan to get on 'um someday. I've been converting ElCheepo Shower Radio/Bluetooth units into small single speaker units (Mounting them to Bookshelf Speakers) and expanding my knowledge in lithium batteries. It's all fun, right?
I did build a set of DML's using the Polyester canvas (8"x8") with the same wooden disc that I used in most of my other builds and found the bass response was improved. I damped the canvas with circles of hot glue from around the center to the outer edges and this did improve the overall sound. When I get around to it, I will get a pic up.. (It's midnite..)
I've always thought that a circle would be perhaps the best, being there would be no corners to create reflections. The area and the material of the circle would then be the highest concern. I have an ambition to focus on that same thought myself..
I have build circle units in the past with foam board and aluminum flashing glued to the rear surface. I understand the theory a little more now and do plan to dive into it in the future..
Might I suggest trying the canvas idea on perhaps an embroidery frame ~10" or more in diameter and keeping with the wooden circle dead center and trussed frame as seen/explained above to hold the exciter. About every 2" from the wooden circle, run a small bead of hot glue to create circles around the back surface of the canvas towards the outside frame. I invision maybe 3? Run a small bead of silicone around the outer frame on the back side where the canvas meets the ring to dampen and to avoid any vibrations to the ring..
I remember a quote from an old Alka Seltzer commercial.. "Try It.. You'll Like It.."
Hi offgrid.
I too ,have been very busy,renovating 5 old turntables I've had lying around for some years now,so that I can record to computer,great fun!
The painters frame was a genius idea and works very well,using a thinner cloth might improve things ,maybe?
I tried the embroidery ring a little bit before moving on (12inch)but it didn't have the huge amount of low end as the painters frames did,maybe if I had persisted I could have done better?
For the painters frames I used 6x2inchx2mm balsa ply ,basically you get the performance of the ply panel itself(600hz to over 20k if I remember rightly) plus the canvas extensions down to 40hz.
I never did get around to trying a dome in the centre to see if this improved things?
If WAF is a problem I thought that the last two pics could be a good idea for listening to music when the other half isn't around.
Just pull them out and away from the wall to the left or right to reduce wall problems (she'll never know).
Hope this helps.
Steve.
I too ,have been very busy,renovating 5 old turntables I've had lying around for some years now,so that I can record to computer,great fun!
The painters frame was a genius idea and works very well,using a thinner cloth might improve things ,maybe?
I tried the embroidery ring a little bit before moving on (12inch)but it didn't have the huge amount of low end as the painters frames did,maybe if I had persisted I could have done better?
For the painters frames I used 6x2inchx2mm balsa ply ,basically you get the performance of the ply panel itself(600hz to over 20k if I remember rightly) plus the canvas extensions down to 40hz.
I never did get around to trying a dome in the centre to see if this improved things?
If WAF is a problem I thought that the last two pics could be a good idea for listening to music when the other half isn't around.
Just pull them out and away from the wall to the left or right to reduce wall problems (she'll never know).
Hope this helps.
Steve.
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How did the handkerchief on embroidery ring sound? Have you tried the exciter on an old vinyl record?
Exciter failure
I was using an 25mm coin type exciter and the coupling plate came unglued to the aluminum former. I was driving them near their limit. I was playing music. I had four of these attached to the panel. The voice coil was not burnt or discolored so that did not fail. The only theory I have is the glue may have softened from the heat transfer of the aluminum former. Any thoughts or suggestions? I really like the size and efficiency of this size exciter.
I was using an 25mm coin type exciter and the coupling plate came unglued to the aluminum former. I was driving them near their limit. I was playing music. I had four of these attached to the panel. The voice coil was not burnt or discolored so that did not fail. The only theory I have is the glue may have softened from the heat transfer of the aluminum former. Any thoughts or suggestions? I really like the size and efficiency of this size exciter.
Kglane.
Is what you are describing similar to this picture of the plastic ring foot, which has detached itself from the coil former.
This has happened to me now and then,I'm wondering if it's down to quality control?
Usually it starts with a slight buzzing now and again on certain pieces of music which is difficult to pin down,this is long before it detaches itself.
I normally use pva to glue the exciter to my panels ,so glued the foot to the coil in the same way using pva with no problems.
As long as you give plenty of time to dry in a warm place( a few days)with a little help from a hair dryer.
I have also on occasion just glued the coil to the panel without the foot,as long as large excursions are not needed!
I usually scuff the foot in the area to be glued just to give a little more grip.
Steve.
Ps.
If the exciters are getting very hot this will obviously fail again, as will the others eventually.
Is what you are describing similar to this picture of the plastic ring foot, which has detached itself from the coil former.
This has happened to me now and then,I'm wondering if it's down to quality control?
Usually it starts with a slight buzzing now and again on certain pieces of music which is difficult to pin down,this is long before it detaches itself.
I normally use pva to glue the exciter to my panels ,so glued the foot to the coil in the same way using pva with no problems.
As long as you give plenty of time to dry in a warm place( a few days)with a little help from a hair dryer.
I have also on occasion just glued the coil to the panel without the foot,as long as large excursions are not needed!
I usually scuff the foot in the area to be glued just to give a little more grip.
Steve.
Ps.
If the exciters are getting very hot this will obviously fail again, as will the others eventually.
Attachments
It's great to see someone playin' with one of my brain farts..
I haven't been doing much lately with DML's. I have a few more designs in thought and plan to get on 'um someday. I've been converting ElCheepo Shower Radio/Bluetooth units into small single speaker units (Mounting them to Bookshelf Speakers) and expanding my knowledge in lithium batteries. It's all fun, right?
I did build a set of DML's using the Polyester canvas (8"x8") with the same wooden disc that I used in most of my other builds and found the bass response was improved. I damped the canvas with circles of hot glue from around the center to the outer edges and this did improve the overall sound. When I get around to it, I will get a pic up.. (It's midnite..)
Amina Invisible Speakers
Hi, does anyone know what the Amina speakers are made from? I know they have a aluminium honeycomb core, and it appears that they have paper type skin, but I'm unsure what this is.
I have made up a carbon fibre skin, no med honeycomb panel based on the size of the dml-10 tectonics speakers (577 x 400mm), annoyingly I didn’t get the rectangle square, so I will need to trim a little more off the length, as found out when making up a test frame. ☺️
I did a quick test with the panel free and was surprised that it went down to around 45hz, although the high frequency drops off too early. I need to clean excess glue from the faces leftover from making the sandwich panel up and put in a frame, so will take some measurements and post results. I wonder if an aluminium core would give better high frequency. I have some carbonfibresheet leftover, so plan on getting some 4mm thick aluminium honeycomb I test and see what the difference will be, but will have a fair bit left over so will be able to test other skins too.
Hopefully will be able to test the CF/nomex honeycomb this weekend and ill post full details of exciter used, positioning, etc along with Rew readings.
Hi, does anyone know what the Amina speakers are made from? I know they have a aluminium honeycomb core, and it appears that they have paper type skin, but I'm unsure what this is.
I have made up a carbon fibre skin, no med honeycomb panel based on the size of the dml-10 tectonics speakers (577 x 400mm), annoyingly I didn’t get the rectangle square, so I will need to trim a little more off the length, as found out when making up a test frame. ☺️
I did a quick test with the panel free and was surprised that it went down to around 45hz, although the high frequency drops off too early. I need to clean excess glue from the faces leftover from making the sandwich panel up and put in a frame, so will take some measurements and post results. I wonder if an aluminium core would give better high frequency. I have some carbonfibresheet leftover, so plan on getting some 4mm thick aluminium honeycomb I test and see what the difference will be, but will have a fair bit left over so will be able to test other skins too.
Hopefully will be able to test the CF/nomex honeycomb this weekend and ill post full details of exciter used, positioning, etc along with Rew readings.
