I love the eggshell dome tweeter that Spedge made for his DML’s. How does it sound?
https://www.diyaudio.com/community/...bonate-matrix-dome.380952/page-2#post-6920666
https://www.diyaudio.com/community/...bonate-matrix-dome.380952/page-2#post-6920666
Xrk.
The eggshell domes were working very well up to a certain point,the problem was that the hard dome was exeggerating 😁 the cavity resonances .
so I had to move on to softer domes or phase plugs .
I have not quite made up my mind which I prefer because of all the other tests panels I have been doing, but I suspect that the very light fabric dome is probably going to be my favourite, depending on panel type ?
These measures cure the cavity and panel surface noise within the coil area.
Steve.
The eggshell domes were working very well up to a certain point,the problem was that the hard dome was exeggerating 😁 the cavity resonances .
so I had to move on to softer domes or phase plugs .
I have not quite made up my mind which I prefer because of all the other tests panels I have been doing, but I suspect that the very light fabric dome is probably going to be my favourite, depending on panel type ?
These measures cure the cavity and panel surface noise within the coil area.
Steve.
Christian.
There is not a lot that can be done about the spider and exciter being too close to the panel , which causes phasing noises and blocks the hf from this area.
the main reason I use a spine is to support the exciter and stop exciter wobble.
the cable and fittings , put the exciter out of balance ,so that if used for playing low frequencies the exciter will wobble from side to side, this is easily seen with the naked eye .
your exciter is a lot heavier, I believe, so needs the support to stop the spider from sagging over time.
The 4 mounting screw holes on your exciter always looked cumbersome to me, Hard to line up and mount , but apart from that they look very similar to my exciter , but with more power handling.
You need that extra power to drive harder heavier panels like ply .
If playing loud heavy music on my exciters attached to a ply panel, my exciters can get very hot !!!
You have many questions in your posts ,which are Hard to answer easily ,without very long explanations.
I can go through them very slowly or you can ask me one of two at a time ,which would be easier for me.
I have too many distractions for such long posts ,my wife for one !
Steve.
There is not a lot that can be done about the spider and exciter being too close to the panel , which causes phasing noises and blocks the hf from this area.
the main reason I use a spine is to support the exciter and stop exciter wobble.
the cable and fittings , put the exciter out of balance ,so that if used for playing low frequencies the exciter will wobble from side to side, this is easily seen with the naked eye .
your exciter is a lot heavier, I believe, so needs the support to stop the spider from sagging over time.
The 4 mounting screw holes on your exciter always looked cumbersome to me, Hard to line up and mount , but apart from that they look very similar to my exciter , but with more power handling.
You need that extra power to drive harder heavier panels like ply .
If playing loud heavy music on my exciters attached to a ply panel, my exciters can get very hot !!!
You have many questions in your posts ,which are Hard to answer easily ,without very long explanations.
I can go through them very slowly or you can ask me one of two at a time ,which would be easier for me.
I have too many distractions for such long posts ,my wife for one !
Steve.
Christian.
Peaks.
when I talk about peaks in the 3k or 10k areas I am not talking about reflections from the edge of the panel, that is a separate issue.
The trouble separating these two peaks is that they are both operating within the coil area.
one is caused by the coil foot radiating inwards towards the centre on the surface of the panel coil area .
The other is the cavity behind the panel surface and the magnet, this air mass starts resonating because of the varying are pressure ,caused by the coil and panel surface moving in and out, compressing the air.
The vents in the coil and foot plus the magnet complicate things even more.
on cone drivers this is behind the dust cap , and can cause major problems (resonances) which is one of the reasons phase plugs are used ,to fill this cavity .
exciters are no different from standard cone drivers except that one is attached to a flat surface and the other is attached to a cone.
Which is why I posted the phase plug forum, as the information is very relevant to exciters and panels.
I could go on, but hope this is enough for you to understand this particular problem ?
Steve.
Peaks.
when I talk about peaks in the 3k or 10k areas I am not talking about reflections from the edge of the panel, that is a separate issue.
The trouble separating these two peaks is that they are both operating within the coil area.
one is caused by the coil foot radiating inwards towards the centre on the surface of the panel coil area .
The other is the cavity behind the panel surface and the magnet, this air mass starts resonating because of the varying are pressure ,caused by the coil and panel surface moving in and out, compressing the air.
The vents in the coil and foot plus the magnet complicate things even more.
on cone drivers this is behind the dust cap , and can cause major problems (resonances) which is one of the reasons phase plugs are used ,to fill this cavity .
exciters are no different from standard cone drivers except that one is attached to a flat surface and the other is attached to a cone.
Which is why I posted the phase plug forum, as the information is very relevant to exciters and panels.
I could go on, but hope this is enough for you to understand this particular problem ?
Steve.
Hello Steve,
Fully agree on the role of the spine. The angle the exciter can have under the cable weight is important. The exciter displacement in the bass is also impressive.
Yesterday to a better comparison between the exciters, I was looking for the Dayton weight... I is not in the data sheet. My balance says 90g not so far from the Tectonics (85g). their dimensions are very similar.
Sorry for the number of questions... Going back to previous posts I was also thinking I am perhaps too long!
As said, be sure your answers help a lot to go forward. Don't worry, we have all our own live, environment. It is already a chance to have the possibility of those exchanges.
Christian
Steve
I just rechecked... 100g seems a better value. At the 1st weighting, there was perhaps an effect of the magnet on the balance? for the new measurements, I have added a mettallic box in between (iron box) to create a screen and a distance. I put one and two exciters. I have an error due to the cables I tried to neutralize. 111g seems high but I found also this value in the spec available at Audiophonics which is not exactly the document from the Dayton web site... Strange. Is my balance wrong or is there a kind of cost saving?
The only conclusion : heavier than the Tectonics by at least 15g
Christian
@spedge, @xrk971
No question in this post! It is not an advertisement either.
Tonight we had boiled eggs for dinner and I played with one of my favorite tool : an boiled egg opener... design for one end or the other one (the war between Lilliput and Blesfucu empires won't happen again).
You get with it a 37mm cap nicely cut! !
Enjoy the egg with a good piece of bread. Collect the caps.
😉
By the way I followed the link in xrk971's post to discover a bit aside what people do with egg skull powder or with baking powder plus super glue... Something to know.
Christian
No question in this post! It is not an advertisement either.
Tonight we had boiled eggs for dinner and I played with one of my favorite tool : an boiled egg opener... design for one end or the other one (the war between Lilliput and Blesfucu empires won't happen again).
You get with it a 37mm cap nicely cut! !
Enjoy the egg with a good piece of bread. Collect the caps.
😉
By the way I followed the link in xrk971's post to discover a bit aside what people do with egg skull powder or with baking powder plus super glue... Something to know.
Christian
I wonder if a thin coat of pliable latex paint on egg dome might cure resonances. Maybe even thin coat of RTV silicone etc.
That’s an amazingly even edge on an egg dome. I would agree that brown pasture raised organic chicken eggs are thicker and much more durable than white pen-raised eggs. They taste better too.
That’s an amazingly even edge on an egg dome. I would agree that brown pasture raised organic chicken eggs are thicker and much more durable than white pen-raised eggs. They taste better too.
Christian.
I don't even want to make egg domes anymore, but I want that gadget !
maybe you should have posted that on the egg midrange forum .
Steve.
I don't even want to make egg domes anymore, but I want that gadget !
maybe you should have posted that on the egg midrange forum .
Steve.
Chistian.
I'm not sure if you read my input on this forum on pro dml, but you might find it interesting.
one of my main concerns with ply was the warping or bowing over time.
and in different weather conditions.
it would only take a little warp in a long panel to move the coil out of its central resting position.
I had free floating exciters on my 6 foot ply panels, and I think I removed the filler damping between the exciter and spine on the 3 foot panel ?
Steve
https://www.audiocircle.com/index.php?topic=138277.40
I'm not sure if you read my input on this forum on pro dml, but you might find it interesting.
one of my main concerns with ply was the warping or bowing over time.
and in different weather conditions.
it would only take a little warp in a long panel to move the coil out of its central resting position.
I had free floating exciters on my 6 foot ply panels, and I think I removed the filler damping between the exciter and spine on the 3 foot panel ?
Steve
https://www.audiocircle.com/index.php?topic=138277.40
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Christian.
I am still slowly going through your post 4420.
You said, you were surprised at not being very annoyed at the peaks in the response , I presume you mean when listening , if I'm correct ?
the peaks only show up when set off by sounds such as sibilance in the 10k area, this can sound very sharp and Hard sometimes,
in combination with the 3k peak it can on certain vocals be very painful to the ear !
but it only shows up now and again on certain vocals.
in a similar way when using large panels down into the low frequencies , now and again certain sounds will set off the panel resonance(drum affect) and the panel will start to make a sound of its own, resonating.
It makes a sort of bong sound, if you press pause on the CD player when this happens you can hear the bong sound fading away.
This is another reason I did not want to push my large panels down into the low frequencies.
Steve.
I am still slowly going through your post 4420.
You said, you were surprised at not being very annoyed at the peaks in the response , I presume you mean when listening , if I'm correct ?
the peaks only show up when set off by sounds such as sibilance in the 10k area, this can sound very sharp and Hard sometimes,
in combination with the 3k peak it can on certain vocals be very painful to the ear !
but it only shows up now and again on certain vocals.
in a similar way when using large panels down into the low frequencies , now and again certain sounds will set off the panel resonance(drum affect) and the panel will start to make a sound of its own, resonating.
It makes a sort of bong sound, if you press pause on the CD player when this happens you can hear the bong sound fading away.
This is another reason I did not want to push my large panels down into the low frequencies.
Steve.
Steve
Thank you to remind us this link. I came to it some days (weeks?) ago but what you remind here about the risk of warping with the plywood is important. I had a first warping problem when I applied a varnish on my panels. I solved it by putting a foam suspension all around the panel. The effort of the warped panel is distributed all along the foam so for now they are still flat. But clearly what about ageing, humidity... there is a risk to go out the resting position or even worse. In addition some might be not in favor of a full foam surronding to kepp the membrane as close as possible to free edge conditions (sorry this is another question... forget).
So if we add the criterias efficiency, environment (temperature, humidity...) in the picture, plywood is not the winner.
In an other hand a spine is necessay to avoid exciter wobbling, effect of the cable weight.
I see in the link you have split the spine functions in 2: avoid the effect of the exciter/cable weight (which is completly necessary), avoid wobbling which more an option (ie a low frequency filter is an answer)... this leads me to think there are perhaps other solutions... I'll try to make a drawing later... The list of design constraints on the spine increases.
To come back to the membrane material which is the first key point :
So who is the winner for a "standard DIYer" ?... Canvas is a good candidate but what about ageing on the tension? Remains EPS/coated EPS?
Christian
Christian.
I am going to talk about foam and rubber mounting panels in answer to your questions, when I get time.
I just used the last test in this box ,and thought I'd show how Quick and easy it is to make a very good sounding panel.
I thought it was solid card ,but it is actually corrugated , it is only 1mm thick and is approx 200mmx160mm.
This should if it was card, cover about 200hz to 20k at least , maybe lower ?
I think my friend was using a very thin corrugated cardboard some time ago but I have not been able to visit him for a few years .
so I am going to give it a go.
I think I will coat one panel with pva and the other in epoxy , it will be interesting to see how they sound, and measure the responses.
Depending on how they sound I may add a fabric dome.
It will cost nothing and if they sound bad it is easy to put them in the bin.
It's a pity you will not be able to hear them with a recording , but I expect the will sound very similar to all my other recordings .
All that is needed is a pair of scissors and some glue.
Steve.
I am going to talk about foam and rubber mounting panels in answer to your questions, when I get time.
I just used the last test in this box ,and thought I'd show how Quick and easy it is to make a very good sounding panel.
I thought it was solid card ,but it is actually corrugated , it is only 1mm thick and is approx 200mmx160mm.
This should if it was card, cover about 200hz to 20k at least , maybe lower ?
I think my friend was using a very thin corrugated cardboard some time ago but I have not been able to visit him for a few years .
so I am going to give it a go.
I think I will coat one panel with pva and the other in epoxy , it will be interesting to see how they sound, and measure the responses.
Depending on how they sound I may add a fabric dome.
It will cost nothing and if they sound bad it is easy to put them in the bin.
It's a pity you will not be able to hear them with a recording , but I expect the will sound very similar to all my other recordings .
All that is needed is a pair of scissors and some glue.
Steve.
Attachments
Steve,
Is the cardboard going back in your thoughts to "a DML of exception" or is it an opportunity for a fast test/demo?
Cardboard was mentioned some weeks ago in Mexjerry's post #4293, also your advice in #3936 to start with it as the "easiest starting point". Going back in my notes, mainly from the audiocircle thread in this case, cardboard if often associated to a research of hardening treatment (ie shellac) and with the problem that come with : implementation, warping. I don't remember seing it in the top of the materials. This remind me I keep in my stock one large sheet of this kind of 1mm cardboard... a candidate for a next test cession... at least to have some measurements.
Christian
Chistian.
One of my first panels was a 1m round 2mm thick corrugated cardboard ,which is in my gallery in the NXT RUBBISH forum.
It sounded so good that I thought ziggy was on to something with dml.
But in the end they sounded too much like corrugated cardboard !
So I moved on.
People were injecting shellac into the flutes of 1cm corrugations, to make the panels more rigid and to prevent the coloration.
the panels warped and in my opinion the soaked panels were too heavy ,even for my 2mm panels.
I get the impression that because my panels are cheap and usually free ,people think the sound is cheap.
nothing could be further from the truth, if I thought that a panel that I had made ,did not sound as good as ,or better than most hi end speakers I've listened to, I would not bother to post ,let alone make a recording.
If I don't like this panel , I will say why and move on.
Everyone seems to be looking for the holy grail of panel materials and spending a lot of money to try and find it.
But it is all around if we could but perceive 😁
I'm going to glue the exciter on before going to bed ,and have a listen tomorrow .
Bonne nuit.
Steve.
One of my first panels was a 1m round 2mm thick corrugated cardboard ,which is in my gallery in the NXT RUBBISH forum.
It sounded so good that I thought ziggy was on to something with dml.
But in the end they sounded too much like corrugated cardboard !
So I moved on.
People were injecting shellac into the flutes of 1cm corrugations, to make the panels more rigid and to prevent the coloration.
the panels warped and in my opinion the soaked panels were too heavy ,even for my 2mm panels.
I get the impression that because my panels are cheap and usually free ,people think the sound is cheap.
nothing could be further from the truth, if I thought that a panel that I had made ,did not sound as good as ,or better than most hi end speakers I've listened to, I would not bother to post ,let alone make a recording.
If I don't like this panel , I will say why and move on.
Everyone seems to be looking for the holy grail of panel materials and spending a lot of money to try and find it.
But it is all around if we could but perceive 😁
I'm going to glue the exciter on before going to bed ,and have a listen tomorrow .
Bonne nuit.
Steve.
Hello Steve,
One interesting and probably extremely intellectually challenging aspect of those loudspeakers is, beside the possibility of a very good loudspeaker, it leads us to reconsider how we understand this technical object, what we believe based on former experiences, readings and which might be in fact not true. The height of the challenge is even higher there are few parts involved and its behavior so different from other drivers.
You are right to point there is not necessary a link between the cost and the result. It is also one of our "intellectual internal filter" effect to link the result to technology and cost. Our brain is so it tries to find explanations or solutions it is at ease with.
The point is to understand, to put words on the quality if possible figures (performance, specification, characteristic) of the materials that gives satisfaction.
The difficulty is as many materials and solutions are possible, what can be reached by one DML builder risks to be difficult to share because of the origin of the material, the lack of metrics. It is much more difficult than cooking! Not mentioning some like spicy food, other not!
An other difficulty is that by the lack of strong shared basis, our activity knows "current of design" created by promising tests so it is not easy to come back to point the fork was created (ie the shellac one)
To come on a less philosophical side... when you mention your experience says "the soaked panel are too heavy" it reinforce my idea (again an intellectual model) there should be a minimal stiffness on aerial mass ratio that makes the panel working (to come on the wording of previous posts D/m or also where to put the coincidence frequency... if it exists for all materials). The other end of this ratio is given by the surface we are ready to give to the final panel.
Let us know how you appreciate those new panels.
On my side, I think to get basic figures from cardboard (stiffness, aerial mass) to bring it in the scope.
Christian