Since you are using 3D printing, I have a suggestion for increase the panel's rigidity: Is it possible to add some carbon fiber tubes on the backside of the panel?
I will try to explain the idea: it would require designing an X format tube guide on the backside of the panel, maybe with a 2mm diameter, so you can fill it with epoxy resin, inserting an 1mm diameter carbon rod.
The epoxi will be glued to each layer of the printing hole, and it may require some marks on the carbon rod to improve adhesion. It would be like an skeleton, that can also be made inside the panel if you want.
I have nooo idea if this has already been tried or suggested on this huge thread.
I will try to explain the idea: it would require designing an X format tube guide on the backside of the panel, maybe with a 2mm diameter, so you can fill it with epoxy resin, inserting an 1mm diameter carbon rod.
The epoxi will be glued to each layer of the printing hole, and it may require some marks on the carbon rod to improve adhesion. It would be like an skeleton, that can also be made inside the panel if you want.
I have nooo idea if this has already been tried or suggested on this huge thread.
Surely it depends on what EPS one is using and what skin...what grades have you tried, and do they all sound good to you?
Have you tried the epoxy on EPS as well? If so, how does the efficiency of a untreated and epoxy coated EPS panel differ?
Interesting idea, but I don't think it will work out. 1mm is very tick. Having a 0.2 layer instead of a 0.1mm really degrades efficiency, so adding 1mm rods and additional epoxy will probably not give great results.
In that case, gluing on thin carbon sheet would probably be better, but then I think you should skip the plastic skin altogether...and if you are already spending on the carbon you might as well glue it onto nomex core instead I guess.
Leob.
On pages 171 to 173 there is a selection of panel recordings from eps to types of canvas panel.
You can use your own judgment as to how good they sound, taking into consideration the problems recording on my phone in a junk filled room and then having to load to my computer and convert to another format 😬
there is also a picture of my hd grade eps panel.
further back I did see a photo of an hd eps panel with a thin sheet of ali glued onto one side, this was enough to totally kill the sound of the eps panel !
steve.
On pages 171 to 173 there is a selection of panel recordings from eps to types of canvas panel.
You can use your own judgment as to how good they sound, taking into consideration the problems recording on my phone in a junk filled room and then having to load to my computer and convert to another format 😬
there is also a picture of my hd grade eps panel.
further back I did see a photo of an hd eps panel with a thin sheet of ali glued onto one side, this was enough to totally kill the sound of the eps panel !
steve.
Junk filled room should be better than an empty room at least!
Very interesting with the dome solutions. I think I will look in to that more to that when I come to a tweaking phase. First I want to get an idea about the thickness, density and dimensions.
I'm thinking about the EPS with hard skin also because that is easy to find in small amounts. The high grade is only available in bulk here. Of course it cannot be any skin, and perhaps skin will influence sound more than the EPS.
Not sure what could work though. Only epoxy, or epoxy with some fibres...or perhaps something like mylar?
Leob,
Thank you for this pictures and the FR.
My comments/questions :
- The HF roll off : you have already answered suspecting some limitation in the measurement chain.
- Is there really a 6dB difference in efficiency? The 3.8mm (orange) curve is above in some regions but they are really very similar. You might use a 5dB scale to have a better view. No need to show FR on a 140dB span.
- The bass roll off are very similar despite the difference of mass and stiffness... like if another parameter like defines the limitation. The bass roll off of a panel in room remains quite high in my list of questions about DML
What is the distance panel/mic in your measurements?
Christian
If you want some good ideas to calibrate in level or check a mic response (ie in HF) : mic calibration thread gives some good ideas and links.
Christian
Christian
Leon.
I have been recommending a 50x50 pva and water mix for eps skins for over 10years now , and have not as yet found a better substitute.
although the guy that designed the pink panel for parts express recommend my 50x50 mix for xps ,I'm not sure that would have been my choice,but I suppose it does help a little, eps and xps are not the same and I believe shouldn't be treated the same.
as for epoxy on eps , the little bit I test coated didn't turn out as expected, I was expecting it to be harder than the pva.
The epoxy doesn't seem to sink into the eps like the pva , and feels quite soft and flexible when pressed and tapped?
The pva feels harder and sounds harder, I was expecting the opposite ?
Epoxy would be my choice for xps , as it seems to give the xps a more glassy sound but without the excessive rigidity and weight.
Life is full of surprises.
But until I or anyone else applies epoxy to the whole of an eps panel I can't be certain how it will sound.
The hd grades of eps by the way have no problems reaching 20k similar to ply, but as you say are hard to get hold of without buying in bulk.
Steve
I have been recommending a 50x50 pva and water mix for eps skins for over 10years now , and have not as yet found a better substitute.
although the guy that designed the pink panel for parts express recommend my 50x50 mix for xps ,I'm not sure that would have been my choice,but I suppose it does help a little, eps and xps are not the same and I believe shouldn't be treated the same.
as for epoxy on eps , the little bit I test coated didn't turn out as expected, I was expecting it to be harder than the pva.
The epoxy doesn't seem to sink into the eps like the pva , and feels quite soft and flexible when pressed and tapped?
The pva feels harder and sounds harder, I was expecting the opposite ?
Epoxy would be my choice for xps , as it seems to give the xps a more glassy sound but without the excessive rigidity and weight.
Life is full of surprises.
But until I or anyone else applies epoxy to the whole of an eps panel I can't be certain how it will sound.
The hd grades of eps by the way have no problems reaching 20k similar to ply, but as you say are hard to get hold of without buying in bulk.
Steve
Sarathssca.
ooops sorry, I keep moving from one panel project to another ,I need to focus on one and not get side tracked.
I have been listening to the cracked cascamite art panel and it seems to be playing ok .
Thanks for reminding me, I need a little prod now and then to keep me moving .
I've been playing around with the 1mm veneer and epoxy panel trying to improve the sound, which has been interesting if a little annoying, but seems to work well playing along side the art panel.
The idea was for my next art panel was to cut the hole in the ply panel before gluing it to the canvas and leave the canvas intact.
Depending on how this goes I might then cut out the canvas in the centre of the coil area and attach a fabric dome, we shall see ?
The idea of the dome is to improve some of the detail in the ply and canvas panel and to sort out exciter problems.
Steve
ooops sorry, I keep moving from one panel project to another ,I need to focus on one and not get side tracked.
I have been listening to the cracked cascamite art panel and it seems to be playing ok .
Thanks for reminding me, I need a little prod now and then to keep me moving .
I've been playing around with the 1mm veneer and epoxy panel trying to improve the sound, which has been interesting if a little annoying, but seems to work well playing along side the art panel.
The idea was for my next art panel was to cut the hole in the ply panel before gluing it to the canvas and leave the canvas intact.
Depending on how this goes I might then cut out the canvas in the centre of the coil area and attach a fabric dome, we shall see ?
The idea of the dome is to improve some of the detail in the ply and canvas panel and to sort out exciter problems.
Steve
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I just re -read your post and though how similar we seem.
I ment to reply sooner.
I still have a pile of hifi world diy supplements under my bed and I built the 20watt valve amp, which I still have , but I need to undo some mods I made to it, which were probably a waste of time !
I had to move out of the front room into the garage as my wife couldn't stand all the wires and experimenting I was doing .
I think the final straw was when she found her Le creuset set propped up about 6ft in the air on poles,used as enclosures for bandor drive units , she wasn't a happy bunny 🐇.
as it happens , moving out and converting the garage into a music room was a great idea, I can play my music as loud as I like without being told to turn it down.
accept for the time she came into my room at about 2am saying she could feel the bed moving across the room, and shouting, turn it down !!!
Happy days.
are you still going to try those panels you mentioned, to see how they sound ?
It would be interesting to know.
Steve.
I don't suspect the HF roll off is a measurement issue. I'm just careful drawing to much conclusions about the details in the HF response with a cheap mic. The overall slope seems correct to my ears at least, and the printed plastic is a bit duller than the cardboard and PC.
I was surprised how close the graphs where after doing the noise measurement, so redid it a couple of times with same result. Indeed I should zoom more. The difference in the graph is 10dB in several places, and perhaps comparing noise and a sweep is not really the same? Can try to do a FR with noise and see if it makes a difference.
Here is the dampened version with more zoom
Indeed bass response is quite similar. It is more uneven in the thinner plate, but that can be the distortion messing up the graph as well. But if anything is tied to mass it is not obvious in the bass region, and the flexibility of the plate seems the most critical factor.
I don't have much experience with epoxy, but there are quite many different types. The one used for making carbon laminates should be worth trying...should be quite hard without the carbon I would have thought.
Sarathssca.
My wife is in London today, church watching ? so I will be able to make up the art panel, which will not take long, I should be able to have a listen tomorrow.
I'm just going to drill the hole in the ply and glue the panel and exciter to the canvas using neat pva.
Just to start with and see how that sounds.
It's as easy as that.
I will be making comparisons with the cascamite panel and the canvas only panel with dome.
Maybe I should set up these two panels today and get used to the sound a little ,to help with comparisons tomorrow.
Thanks again , for reminding me.
Steve.
My wife is in London today, church watching ? so I will be able to make up the art panel, which will not take long, I should be able to have a listen tomorrow.
I'm just going to drill the hole in the ply and glue the panel and exciter to the canvas using neat pva.
Just to start with and see how that sounds.
It's as easy as that.
I will be making comparisons with the cascamite panel and the canvas only panel with dome.
Maybe I should set up these two panels today and get used to the sound a little ,to help with comparisons tomorrow.
Thanks again , for reminding me.
Steve.
While I was setting up the art panel I suddenly remembered that my next test set-up I was planning was going to be with the panel on the front as in the picture.
I'm in a bit of a quandary as to which to go for.
the idea was to try and get a little more detail from the ply on the front side and maybe cutting a larger area of canvas at the back for less damping ?
it doesn't look too bad , in fact I like the look.
I will only have one panel left to experiment with after this panel .
I got the four panels very cheaply in a 4 pack .
Mmmmmm.
Steve.
I'm in a bit of a quandary as to which to go for.
the idea was to try and get a little more detail from the ply on the front side and maybe cutting a larger area of canvas at the back for less damping ?
it doesn't look too bad , in fact I like the look.
I will only have one panel left to experiment with after this panel .
I got the four panels very cheaply in a 4 pack .
Mmmmmm.
Steve.
Attachments
Ok , I've made up my mind, I've glued the ply to the front of the canvas panel but without the hole for the dome, but I've cut a hole in the canvas so that the exciter will mount directly on to the ply.
This is going to take a lot longer now as I have to wait for the canvas to dry before gluing the exciter on.
I've placed weights on the canvas and ply to keep it flat and stop it bubbling.
Steve.
This is going to take a lot longer now as I have to wait for the canvas to dry before gluing the exciter on.
I've placed weights on the canvas and ply to keep it flat and stop it bubbling.
Steve.
Attachments
Hi Steve
I have a sample of the material you have inquired about on my work desk, It is extremely robust and resilient to compression with walls and ribs less that 1mm in thickness, I assume the material has a hardness produced to take the impact of heavy plant and point loading.
I just have to request for the permission to take a few full sheets home with myself, this will give me a base material that can be tried in different thicknesses and possibly even a Two Ply Lamination and to keep the contact between surfaces quite tight, use 0.8mm thick double sided Teflon tape as the bonding material.
As said I can make some of this available to be trialled, I'm sure I could package a few 400mm x 400mm 'ish' Panels to be posted, if my weekly Journey's are not passing local to an interested party.
I am also keen to try out a Natural Product and Canvas is very attractive, especially after hearing recordings on this Thread with it used as the DPS.
There is one more itch to scratch for a use of a Natural Material and that will be a very thin wood material with a soaking of Shellac, as I have seen in other threads where damping is a required property for a material that a Shellac Soak Coating can enhance the measurements recorded for damping and dissipation of a material.
Shellac is as Natural as it gets, as it is produced from secretions from the Lac Beetle insect, it is very stable and long lasting.
It also has very minimum elastic properties and is resistant to UV break down.
Most importantly, and to really get the party going, Is there any 'Exciters' I could purchase from a UK members redundant parts?
I have a sample of the material you have inquired about on my work desk, It is extremely robust and resilient to compression with walls and ribs less that 1mm in thickness, I assume the material has a hardness produced to take the impact of heavy plant and point loading.
I just have to request for the permission to take a few full sheets home with myself, this will give me a base material that can be tried in different thicknesses and possibly even a Two Ply Lamination and to keep the contact between surfaces quite tight, use 0.8mm thick double sided Teflon tape as the bonding material.
As said I can make some of this available to be trialled, I'm sure I could package a few 400mm x 400mm 'ish' Panels to be posted, if my weekly Journey's are not passing local to an interested party.
I am also keen to try out a Natural Product and Canvas is very attractive, especially after hearing recordings on this Thread with it used as the DPS.
There is one more itch to scratch for a use of a Natural Material and that will be a very thin wood material with a soaking of Shellac, as I have seen in other threads where damping is a required property for a material that a Shellac Soak Coating can enhance the measurements recorded for damping and dissipation of a material.
Shellac is as Natural as it gets, as it is produced from secretions from the Lac Beetle insect, it is very stable and long lasting.
It also has very minimum elastic properties and is resistant to UV break down.
Most importantly, and to really get the party going, Is there any 'Exciters' I could purchase from a UK members redundant parts?
Leob,
The HF roll off is not very steep so why not but the bass roll off is unusually steep. Almost the same for both panels is also strange. There is perhaps something to check.