Andre Bellwood.
Thank you.
It was that sort of setup I was thinking of for the proplex, not 5000watts 😃
My friend does those sort of gigs but mainly with acoustic guitar.
I was wondering whether I might make him some panels.
Steve.
Thank you.
It was that sort of setup I was thinking of for the proplex, not 5000watts 😃
My friend does those sort of gigs but mainly with acoustic guitar.
I was wondering whether I might make him some panels.
Steve.
The setup I'm aiming for will eventually be a small 1,000W system driving 2 x 250W panels and a 500W sub, and should be able to deliver 120db peak SPL, ideal for a one-man setup or a small folk band indoors. I'd suggest double that for a rock band with live drums and bass playing through the P.A.
I suspect that Proplex is not Polycarb but Polypropylene, the same stuff they use to make Corflute/Correx signboards etc. Unfortunately it's at the bottom of my pile of tested, parametrised and discarded samples. It's just way too dense and far too highly damped to be of any use for my application IF it's the stuff I'm thinking of.
But I'd be interested if you can get me material properties on Proplex (density, shear modulus, Young's modulus, tensile strength, etc etc) or maybe point me at a supplier who would submit these details. I have tried to Google it, but have found some wholly unrelated answers.
Cheers,
A.
Proplex is PP
| Homopol | Copolym | ||
| Density | / kgm-3 | 905 | 905 |
| Price / Tonne | / £ | 680 | 620 |
| Tensile Strength | / Mpa | 33 | 25 |
| Tensile Modulus | / Gpa | 1.4 | 1.0 |
| Elongation at Break | / % | 150 | 300 |
| Hardness | / Rockwell "R" Scale | 90 | 80 |
| Notched Izod Impact | / kJm-1 | 0.07 | 0.1 |
+ @spedge
As far as remember, this is an open topic on EPS. Several of us faced the lack of HF with EPS. I am currently in the opinion that the EPS we had is to light, not stiff enough; a too low mechanical impedance that leads to a high pass filter with the mass of the voice coil. the only way I see as a counter measure is to increase the stiffness and the weight by the quantity of PVA coating... and starting from a not too light EPS. I would appreciate to have figures about that.
Christian
Hi Christian,
I suspect the EPS is too soft to transmit vibration from a back surface to a front surface. So it does not matter how stiff we make those surfaces (I used Kevlar and UHMWP!) and it does not matter how strong or heavy the panel is, but if the core is too soft, then HF cannot "penetrate" from driver on the back to acoustic radiation on the front.
I did try to reduce this effect by using hard pucks in the EPS, but it made little difference. Maybe they are too small?
I keep denying it, but the solution seems to be 2mm honeycomb panels with CF(?) skins... Eish.
In room measurements of 25mm eps 70grade will reach 10k.
But can radiate from the exciter area up to 20k.
If you take measures to prevent cancellations in the coil atea.
Steve.
But can radiate from the exciter area up to 20k.
If you take measures to prevent cancellations in the coil atea.
Steve.
NXT quote,
meaning that DM panels should be held effectively rigidly at edges and/or clamped medially.
NXT states.
If this is the case, that there is a lack of transfer of energy from back to front, then there should be a difference in frequency response comparing back and front. I’m Assuming that the exciter is directly connected to backside and thus inducing waves in the panel.
’Thomas
A possiblability?
AlumaComp Aluminum, 30"x36" Archival Painting & Mounting Panel
Not cheap.
Polyethylene core 1/8"
Size : 30" x 36" x 3/16"
Seems heavy, but perhaps not much heavier than 6mm Proplex.
I've got some from having mounted a painting.
You can cut it with a good razor knife.
On my list to try.
AlumaComp Aluminum, 30"x36" Archival Painting & Mounting Panel
Not cheap.
Polyethylene core 1/8"
Size : 30" x 36" x 3/16"
Seems heavy, but perhaps not much heavier than 6mm Proplex.
I've got some from having mounted a painting.
You can cut it with a good razor knife.
On my list to try.
Attachments
Thanks BC,
Given those numbers (just by density alone,) Proplex is as suspected: too heavy for decent efficiency. I will have to quadruple the size of my amps to get the same SPLs.
Thanks Thomas,
I do recall doing "back-side" tests a while ago, and noting that the FR definitely goes higher than front side. I'll do the same tests on these panels today and see if I pick up anything note-worthy.
It is indeed polypropylene - the polycarbonate twin cell is a different animal - much stiffer and more glass like.
Australian proplex is marketed as corflute and is not heavy, at least in the 5mm thickness I have which weighs 890 gsm versus 1400 gsm for 3mm poplar ply
https://corex.com.au/product/corflute/
Eucy
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PP is also highly damped. There seems to be some recovery of performance due to structure I.e. spaced skins with a ribbed core, but I am not in a rush to try it.
Burnt - I recommend you do try it - it's very cheap to buy, and easy to try - I guarantee you'll be surprised, as I most definitely was. Try the 5mm thickness.
Eucy
See my posts above Andre - PP may be dense in solid sheet form, but not in cellular sheet form
Eucy