Soundscape Posted June 3, 2016 Share Posted June 3, 2016 FWIW I notice that the polymax xhd is stiffer on one side, softer on the other. Assuming the stiffer side is denser I'm guessing it works better when installed stiff side away from the wall/ceiling. That's how I put mine up anyway and when I build a layered trap I'll make sure that each layer is oriented that way. Link to comment Share on other sites More sharing options...
Ugly Posted June 3, 2016 Author Share Posted June 3, 2016 FWIW I notice that the polymax xhd is stiffer on one side, softer on the other. Assuming the stiffer side is denser I'm guessing it works better when installed stiff side away from the wall/ceiling. That's how I put mine up anyway and when I build a layered trap I'll make sure that each layer is oriented that way.That was also my assumption. Plus it looks better that way if you're not covering. 1 Link to comment Share on other sites More sharing options...
jamiebosco Posted June 3, 2016 Share Posted June 3, 2016 any gap is better than none handy modelling tool: http://www.acousticmodelling.com/porous.php Assuming Polymax XHD 50mm gap vs no gap - blue is 50mm air gap, green against the wall no gapping.JPG 50mm gap vs 100mm gap - blue is 50mm air gap, green 100mm air gap gapping.JPG cheers Mike Thanks Mike! It definitely appears to make a difference under 300hz, I will have to decide if it's worth the inevitable arguement Link to comment Share on other sites More sharing options...
Guest Muon Posted June 3, 2016 Share Posted June 3, 2016 I'm disappointed I thought for sure we would hear from this guy at some point. Some great ideas in this thread, just not in this post. Link to comment Share on other sites More sharing options...
Soundscape Posted June 4, 2016 Share Posted June 4, 2016 (edited) How do you explain the differences here? A larger gap seems to reverse the efficacy of different thicknesses. Is that right? Or should the flow resistivity change with different thicknesses? Edited June 4, 2016 by Dave O))) Link to comment Share on other sites More sharing options...
b.d Posted June 8, 2016 Share Posted June 8, 2016 Those looking for 48kg batting in Melbourne there is this at reasonable quantity and price http://www.ambisol.com.au/ultratel-board-plain-50mm-2400mm-x-1200mm-x-50mm/ Link to comment Share on other sites More sharing options...
~Spyne~ Posted June 20, 2016 Share Posted June 20, 2016 Those looking for 48kg batting in Melbourne there is this at reasonable quantity and price http://www.ambisol.com.au/ultratel-board-plain-50mm-2400mm-x-1200mm-x-50mm/ Cheers, I just stumbled across these guys this afternoon and then found your post in the myriad of google results for "polymax xhd". Certainly looks the goods with their NRC values, only negative is that it looks to be a fibreglass/wool hybrid which would be less 'pleasant' to work with compared to the polyester of XHD batts. My local finally got back to me saying they can only order in minimum of 3 packs of the XHD (12-18 batts!!) but can get single packs (4-6 batts) of the Polymax LD...I politely said thanks but no thanks Anyone around VIC got some XHD 50mm or 75mm leftover? Link to comment Share on other sites More sharing options...
nzlowie Posted June 22, 2016 Share Posted June 22, 2016 Some good info here guys. Is the air gap mentioned to be sealed, eg the outside edges should extend back to the wall and seal there? If the panel is 100mm thick then the sides would be a total of 200mm deep. So if no air gap is bad, 50 is good but 100mm is better..... how about free standing ? I've made panels so now I need to make sure I optimize them. REW has shown me that room isn't that great. Sent from my D5833 using Tapatalk Link to comment Share on other sites More sharing options...
Ugly Posted June 22, 2016 Author Share Posted June 22, 2016 I don't think the air gap has to be sealed because it would be pretty had to do. i.e. lower frequencies will pass straight through most framing material so no point. At least that's what I figure. Link to comment Share on other sites More sharing options...
almikel Posted June 29, 2016 Share Posted June 29, 2016 air gap doesn't need to be sealed for absorption traps air gap does need to be sealed in a membrane (pressure trap), but that's another discussion Mike 1 Link to comment Share on other sites More sharing options...
Guest Posted June 29, 2016 Share Posted June 29, 2016 http://www.stereo.net.au/forums/index.php/topic/75988-a-battery-based-audiophile-story/page-51 Been working on a similar thing, but different principal of operation check it out Link to comment Share on other sites More sharing options...
everdingk Posted January 2, 2019 Share Posted January 2, 2019 On 28/02/2016 at 8:38 PM, Ugly said: I knocked up a frame today for some recently acquired Polymax and I'm pretty chuffed with how it turned out. Normally, anything I build requires many visits to bunnings and much swearing....today however the hi-fi gods must have been smiling as it all just worked. I cut my polymax with an small angle grinder a couple of weeks ago. It worked quite well however it needed something to neaten it up so I decided to build some frames. I wanted a corner trap so I used a double thickness of Polymax XHD 50. I used some very cheap, light pine (92mm x 8mm) with some little metal brackets to secure it inside the corners. Some moulding added to the front to hide the rough polymax edges. I'll paint or stain it once I've decided on colours for the room these are going in. Materials came to about $30 plus about $40 for the polymax. All up $70 for a panel seems pretty reasonable. The panel is 1600 x 620 and is designed to sit on my desk straddling the corner to the ceiling. This looks amazing..... and exactly what I am trying to achieve at the moment. I am like you..... usually end up back and forth to Bunnings to get this right Just wondering... when you say " I used some very cheap, light pine (92mm x 8mm) with some little metal brackets to secure it inside the corners" what did you mean by metal brackets in the corners. thanks 1 Link to comment Share on other sites More sharing options...
Ugly Posted January 2, 2019 Author Share Posted January 2, 2019 This looks amazing..... and exactly what I am trying to achieve at the moment. I am like you..... usually end up back and forth to Bunnings to get this right [emoji4] Just wondering... when you say " I used some very cheap, light pine (92mm x 8mm) with some little metal brackets to secure it inside the corners" what did you mean by metal brackets in the corners. thanks I used this one (or something very similar)The only reason I thought it nessesary was that the pine was so thin I could only use very small screws. I figured this would give it just a little more strength. Link to comment Share on other sites More sharing options...
everdingk Posted January 3, 2019 Share Posted January 3, 2019 7 hours ago, Ugly said: I used this one (or something very similar) The only reason I thought it nessesary was that the pine was so thin I could only use very small screws. I figured this would give it just a little more strength. aahhh.... OK. Thanks for the reply. I thought you meant secure the polymax to the frame but now I read it again that makes sense. Did you have any concerns about the polymax falling forward out of the frame or does the moulding help with this? Just out of curiosity what width is that moulding? thanks again.... will be off to bunnings soon. cheers Link to comment Share on other sites More sharing options...
Ugly Posted January 3, 2019 Author Share Posted January 3, 2019 aahhh.... OK. Thanks for the reply. I thought you meant secure the polymax to the frame but now I read it again that makes sense. Did you have any concerns about the polymax falling forward out of the frame or does the moulding help with this? Just out of curiosity what width is that moulding? thanks again.... will be off to bunnings soon. cheersThe polymax won't fall out the front as the moulding holds it in place. It is roughly 25mm.I used two 50mm sheets of polymax with a brace across the back to hold it in place (as in the picture). Depending on the size of your traps you may need to add more bracing to the rear. Link to comment Share on other sites More sharing options...
Ugly Posted January 3, 2019 Author Share Posted January 3, 2019 This is the cross piece that hold it in place at the rear. Link to comment Share on other sites More sharing options...
everdingk Posted January 3, 2019 Share Posted January 3, 2019 7 hours ago, Ugly said: This is the cross piece that hold it in place at the rear. nice thankyou! Link to comment Share on other sites More sharing options...
everdingk Posted January 9, 2019 Share Posted January 9, 2019 On 03/01/2019 at 2:36 PM, Ugly said: The polymax won't fall out the front as the moulding holds it in place. It is roughly 25mm. I used two 50mm sheets of polymax with a brace across the back to hold it in place (as in the picture). Depending on the size of your traps you may need to add more bracing to the rear. Hey Mate, Finally got all my materials and will start building soon. I've not got much experience with woodworking.... just wondering how you attached the mouding? Did you use little screws or nail got or what? thanks again Link to comment Share on other sites More sharing options...
Ugly Posted January 9, 2019 Author Share Posted January 9, 2019 Tiny little screws. Make sure you pre drill the holes or you may split the timber. Link to comment Share on other sites More sharing options...
Ugly Posted January 9, 2019 Author Share Posted January 9, 2019 Link to comment Share on other sites More sharing options...
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