Hkbuy6.
The 25mm eps 70 grade which is easy to get hold of in the uk, looks like it is supposedly 14kg/m3.
If you tap on the menu top left and then go to polystyrene cut to size it will show a video of grades and density.
If you tap on the grades box it shows the other grade weights for ordering.
https://www.custompac.co.uk
Steve.
The 25mm eps 70 grade which is easy to get hold of in the uk, looks like it is supposedly 14kg/m3.
If you tap on the menu top left and then go to polystyrene cut to size it will show a video of grades and density.
If you tap on the grades box it shows the other grade weights for ordering.
https://www.custompac.co.uk
Steve.
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Thanks for the info Spedge.
The heavier 150grade is 22.5kg, seems a little lower then my expectation.
Do you know the "HD" you mentioned is around whcih grade? Or anyone tried the UHD their actual weight?
On my test piece the 22kg has not much different then 15kg. That's why you reported they're sound similar between the hi/low grade EPS. Because even hi/low grade their actual density level are quite close.
I suggest you try EPS over 35kg(10mm perfered) and report your comment.
And I found that if under 13kg will dramtically degrade the sound quality. I guess is because the density dropped to a threshold, there're not enough "network" to carry the wave. Like the Balsa I tried.
Sorry for my English. Hope there will not have too much difficulty for reading.
Some pictures of sanding the graphite panel.
Pic 1.
The grey of the graphite is much darker in the skin,the first picture shows the corner I sanded.
Pic 2.
I used a 50x50 mix on this side but decided to thin the mix a little more on the front side as the sun was drying it very quickly .
I want it to soak in a little more.
I prefer to give the surface a good wetting rather than just a thin skin.
When the water evaporates there will be very little left just a small amount of pva.
Pic 3.
I decided to add a small sponge to hang the panel with , it is much more stable , but it takes more time to dry.
Also you can see in the bottom right where I used a much coarser sand paper to compare results.
Unfortunately I went down quite low and very quickly.
The surface might have been a little more fluffy but am not sure which is best.
Tech ingredients seem to like their panels this way without a skin .
This gives the panel a soft sound which some may prefer ?
I was in a hurry so could have done without waiting for the sponge to dry.
I was going to test the panel with the soft surface but decided I did not want graphite dust in my room.
And I already know what this sounds like as I already have this sort of eps panel.
Steve.
Pic 1.
The grey of the graphite is much darker in the skin,the first picture shows the corner I sanded.
Pic 2.
I used a 50x50 mix on this side but decided to thin the mix a little more on the front side as the sun was drying it very quickly .
I want it to soak in a little more.
I prefer to give the surface a good wetting rather than just a thin skin.
When the water evaporates there will be very little left just a small amount of pva.
Pic 3.
I decided to add a small sponge to hang the panel with , it is much more stable , but it takes more time to dry.
Also you can see in the bottom right where I used a much coarser sand paper to compare results.
Unfortunately I went down quite low and very quickly.
The surface might have been a little more fluffy but am not sure which is best.
Tech ingredients seem to like their panels this way without a skin .
This gives the panel a soft sound which some may prefer ?
I was in a hurry so could have done without waiting for the sponge to dry.
I was going to test the panel with the soft surface but decided I did not want graphite dust in my room.
And I already know what this sounds like as I already have this sort of eps panel.
Steve.
Attachments
Hkguy6.
I'm not sure I agree with you about the low grade eps being an inferior quality sound .
I have made recordings on this site of 10mm low grade eps which surprised me of how good it sounded and measured.
Basically I used the same technique as I am using with the 70 grade graphite panel.
And I will be comparing the panels at a later date and probably doing some recordings to show the difference , if any ?
EPS is so far my favourite dml material , but which grade I'm not sure ?
I have only been playing with DML for over 10 years, and don't like to rush things 🤣
Steve.
I'm not sure I agree with you about the low grade eps being an inferior quality sound .
I have made recordings on this site of 10mm low grade eps which surprised me of how good it sounded and measured.
Basically I used the same technique as I am using with the 70 grade graphite panel.
And I will be comparing the panels at a later date and probably doing some recordings to show the difference , if any ?
EPS is so far my favourite dml material , but which grade I'm not sure ?
I have only been playing with DML for over 10 years, and don't like to rush things 🤣
Steve.
Yes that's why I ask the exact weight of the EPS you tried.
We're talking the same material but using different "grading" system. The "low grade", "HD" you say may not pair with my "under 13kg/m3", "over 35kg/m3.
The 11kg/m3 bad sound EPS I tried is very fragile. It's difficult to sanding because even a 120-grade sanding paper will destory the board (little balls apart). So I don't think your "low grade" board is lower as what I'm saying.
We're talking the same material but using different "grading" system. The "low grade", "HD" you say may not pair with my "under 13kg/m3", "over 35kg/m3.
The 11kg/m3 bad sound EPS I tried is very fragile. It's difficult to sanding because even a 120-grade sanding paper will destory the board (little balls apart). So I don't think your "low grade" board is lower as what I'm saying.
I think it's because you guys so good and have patient to understand my lame English. Thank you.
Hkguy6.
I know what you mean about varying quality, and standards.
Some years ago I stopped experimenting with the large EPS 70grade panels from my local DIY store because the quality suddenly changed, it was still supposedly 70 grade but there were too many holes in the surface.
The same can happen with the lower grades, at the moment I am listening to a low density soft eps 25mm panel next to the graphite panel.
This panel is a good quality lower grade as It has a good smooth surface without holes.
It is soft when squeezed, and has a similar sound to a sanded panel with no skin applied.
I will coat this with diluted pva as usual , without sanding ,as the lower grades do not have the hard pva skin( the ones I have used anyway).
I just found my 40cmx40cmx10mm hd or vhd eps panel, it weighs 57g ,so that is about 35.625 kg/m3 .
The cost of buying a full sized panel like this back then ,would have been far too expensive, and things haven't changed.
Steve.
I know what you mean about varying quality, and standards.
Some years ago I stopped experimenting with the large EPS 70grade panels from my local DIY store because the quality suddenly changed, it was still supposedly 70 grade but there were too many holes in the surface.
The same can happen with the lower grades, at the moment I am listening to a low density soft eps 25mm panel next to the graphite panel.
This panel is a good quality lower grade as It has a good smooth surface without holes.
It is soft when squeezed, and has a similar sound to a sanded panel with no skin applied.
I will coat this with diluted pva as usual , without sanding ,as the lower grades do not have the hard pva skin( the ones I have used anyway).
I just found my 40cmx40cmx10mm hd or vhd eps panel, it weighs 57g ,so that is about 35.625 kg/m3 .
The cost of buying a full sized panel like this back then ,would have been far too expensive, and things haven't changed.
Steve.
Thanks for the details Steve.
I have no experience on EPS surface difference. All the boards I tried are quite smooth surface I will say.
And yes even the same density board they also have "rigidity" different. This is what I heard from my EPS supplier.
EPS for packing normally will have less rigidity then for scuplting or insulation.
So if I didn't misunderstand. Your "good quality" low grade, the 70 grade(supose 14kg/m3), and the 35kg/m3 you tried all sounds similar?
Strange that it's quite a different to my result!
My best sounding EPS is a ~20x60x1cm 41kg/m3 board. Because it's sound so good, I also made an exact same size 13kg/m3 board to compare. I use them on L/R then play mono and pink noise. They are Very different on FR and also imaging.
I have no experience on EPS surface difference. All the boards I tried are quite smooth surface I will say.
And yes even the same density board they also have "rigidity" different. This is what I heard from my EPS supplier.
EPS for packing normally will have less rigidity then for scuplting or insulation.
So if I didn't misunderstand. Your "good quality" low grade, the 70 grade(supose 14kg/m3), and the 35kg/m3 you tried all sounds similar?
Strange that it's quite a different to my result!
My best sounding EPS is a ~20x60x1cm 41kg/m3 board. Because it's sound so good, I also made an exact same size 13kg/m3 board to compare. I use them on L/R then play mono and pink noise. They are Very different on FR and also imaging.
Hkguy6.
The graphite eps that I am working on at the moment, works out at about 14.6 kg/m3 ,all the seller says on their site is, weight 13kg ?
The hard skin on the 70 grade, from the cutting with the hot knife ,has a very brittle sound to it, I found that replacing this skin with pva was a vast improvement and removed the polystyrene sound.
Steve.
The graphite eps that I am working on at the moment, works out at about 14.6 kg/m3 ,all the seller says on their site is, weight 13kg ?
The hard skin on the 70 grade, from the cutting with the hot knife ,has a very brittle sound to it, I found that replacing this skin with pva was a vast improvement and removed the polystyrene sound.
Steve.
Sounds good?
I don't suprise it's around 15kg. From your pic I see it's balls size quite big.
How it's rigidity when compare with normal 70 grade?
Shame that I can't find any graphite EPS thinner then 5cm here. And I don't want to built a hot-wire cutter just for this.
Yes I have the same impression as yours. EPS with skin sounds brittle. My previous post said it sounds Glassy and Honky.
XPS also has this brittle sound no matter how deep I sand out it's skin.
I don't suprise it's around 15kg. From your pic I see it's balls size quite big.
How it's rigidity when compare with normal 70 grade?
Shame that I can't find any graphite EPS thinner then 5cm here. And I don't want to built a hot-wire cutter just for this.
Yes I have the same impression as yours. EPS with skin sounds brittle. My previous post said it sounds Glassy and Honky.
XPS also has this brittle sound no matter how deep I sand out it's skin.
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Hkguy6.
So far I have not noticed much difference between the ordinary 70 grade and the graphite 70 grade but I have not made like for like comparisons.
Ziggy over on NXT RUBBISH forum used to like vh grade and very large panels ,he was in Australia.
Did you listen to my recordings of the very low density 10mm panels?
The sound and measurements were very good.
Steve.
So far I have not noticed much difference between the ordinary 70 grade and the graphite 70 grade but I have not made like for like comparisons.
Ziggy over on NXT RUBBISH forum used to like vh grade and very large panels ,he was in Australia.
Did you listen to my recordings of the very low density 10mm panels?
The sound and measurements were very good.
Steve.
As luck would have it, I came across this post on page 180 which I made , i was looking for my low grade panel recordings at the time.
The pictures are in revers order, which is a little confusing.
The link to my pictures on the NXT RUBBISH site shows plots of the original vh grade 40×40x20mm panel without paint or shape cutting.
If you tap on the uploaded pictures at the top it will show my large 25mm 70 grade panel responses plus other panels.
Steve.
This is my epoxy coated 5mm xps on page 190.
There are recordings and pictures of these panels and responses on this page.
I had forgotten the tea bag dome idea , I must write things down !
Steve.
At last I found it.
This is page 249.
This is the start to my testing very thin 10mm eps .
One is ,I thought about 70 grade the other is a very soft lower grade, very bendy.
I listened and measured , before coating in pva.
You have to go on a few more pages for improvements and recordings.
On post 4966 on this page I also mention the soft low grade surface.
Steve.
Hello Hkguy6
You come here to an interesting point which isthe conditions for a material to carry on the waves. Some patents start with a sentence like "for a material able of bending waves...". I would be interested to see what are those conditions. Probably something around bending stiffness, aerial density, damping but it seems there is a kind of threshold.
For your English. don't worry, you are not the only one having an other mother language ;-)
Christian
Reading these interchanges, it seems to me that you guys could devise some common and simple means of testing the material so you can get measure of similarity across national boundaries.
What comes to mind is crushability... How about using a common sized coin or similar with say a 2 or more kg weight applied and see how far it indents the material
That may mean more than density comparisons
Eucy
I finally found the recording .
I should have made another recording as I had the microphone too close to the LF driver , there is too much bass and lower midrange from the TLS making it sound mushy.
Maybe I'll do that recording soon.
Steve.
I'm pleased to report that the first part of the build was a rousing success 👍😊. The girls were rather dubious upon first seeing the exciters, but after demonstrations with various household objects (pizza box, window, cutting board etc.) they became a great deal more interested.
We took a trip to a big box store and ended up buying both 30mm XPS and 20mm EPS panels (the latter were on special for the equivalent of $8). I couldn't find information regarding the EPS density, but this project is about fun and education as opposed to chasing fidelity. The thinnest plywood they had was 6mm so that was not bought. Cutting and fitting the panels into the car along with 4 people was a very amusing exercise 😆.
Back at home the girls then cut, shaped and sanded the panels with supervision, and they really enjoyed the process. We then listened back and forth between the XPS and EPS panels (just holding the exciter in place, not permanently attached), and the preference was universally for EPS. Thank you again for the advice to try EPS! The final panel size was around 90cm by 120cm.
Once the exciters were properly attached we spent a couple of hours listening with the panels just propped against the wall and a sub connected. My partner was absolutely amazed by the sound (bear in mind the family had been listening exclusively to integral TV speakers up until now), and the girls fought good-naturedly about whose turn it was to choose music.
To my ears, the panels are somewhat shouty / harsh, but given the constraints of the project and the desired outcome I'm very happy indeed 😀.
Tomorrow or Wednesday we'll apply PVA and hang the panels. On this note - what dilution should the PVA be? 1:1, 2:1 ?
We took a trip to a big box store and ended up buying both 30mm XPS and 20mm EPS panels (the latter were on special for the equivalent of $8). I couldn't find information regarding the EPS density, but this project is about fun and education as opposed to chasing fidelity. The thinnest plywood they had was 6mm so that was not bought. Cutting and fitting the panels into the car along with 4 people was a very amusing exercise 😆.
Back at home the girls then cut, shaped and sanded the panels with supervision, and they really enjoyed the process. We then listened back and forth between the XPS and EPS panels (just holding the exciter in place, not permanently attached), and the preference was universally for EPS. Thank you again for the advice to try EPS! The final panel size was around 90cm by 120cm.
Once the exciters were properly attached we spent a couple of hours listening with the panels just propped against the wall and a sub connected. My partner was absolutely amazed by the sound (bear in mind the family had been listening exclusively to integral TV speakers up until now), and the girls fought good-naturedly about whose turn it was to choose music.
To my ears, the panels are somewhat shouty / harsh, but given the constraints of the project and the desired outcome I'm very happy indeed 😀.
Tomorrow or Wednesday we'll apply PVA and hang the panels. On this note - what dilution should the PVA be? 1:1, 2:1 ?
Yup, the idea is to suspend them next to the TV.
I'm going to hang them at the current size of 90cm by 120cm and see how they sound. We can always trim them down thereafter.
How will making them smaller affect the lower frequencies?