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Cheap acoustic panels from China/Hong Kong

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Cheap acoustic panels from China/Hong Kong

Postby Elephone » Wed Nov 14, 2018 6:16 pm

Hello, just wondering if anyone knows if these cheap panels actually do what they're supposed to. The more you buy the cheaper it is per panel see, so I'd rather ask here before buying a load. Can't really trust the reviews because they're not necessarily knowledgeable customers.

https://www.ebay.co.uk/itm/12-Pack-Acou ... 2974100735

Thanks
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Re: Cheap acoustic panels from China/Hong Kong

Postby Hugh Robjohns » Wed Nov 14, 2018 6:38 pm

I'm not a huge fan of foam at the best of times... cheap foams not only tend to crumble and discolour in a relatively short period, but without any specific details of fire certification I'd be loathe to use any in the house as foams can generate extremely toxic fumes when ignited!

On top of that, the specific panels you linked to are only 1 inch thick (at best) which rather limits their operating bandwidth...

In short... I wouldn't! Either build your own panels with rockwool, or save up your money and buy worthwhile acoustic panels which are massively more effective and attractive than those foam wedges such as those from GIK UK... :-) (other creditable suppliers are available...)

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Re: Cheap acoustic panels from China/Hong Kong

Postby Wonks » Wed Nov 14, 2018 6:42 pm

They look far too thin to be of much use except at the highest frequencies. Also, they don't appear to have any fire-retardant properties, so could be a big fire risk.

They don't even state if the foam is open cell or not. Not something that I'd consider using.
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Re: Cheap acoustic panels from China/Hong Kong

Postby Elephone » Wed Nov 14, 2018 6:51 pm

Thanks. So rockwool both insulates and prevents reflections? Would this also be a good thing to sound-proof an unused door?

I'm surprised someone hasn't set up a business pricing everyone else out of the market by offering cheap solutions that make it virtually pointless to do a DIY job.

I mean, slicing and covering rockwool with some fabric is relatively easy to do on an industrial-like scale but not so much for any DIY'er.

https://www.ebay.co.uk/sch/i.html?_from ... c&LH_BIN=1
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Re: Cheap acoustic panels from China/Hong Kong

Postby Wonks » Wed Nov 14, 2018 7:08 pm

Acoustic treatment and soundproofing are two different things. You'd be better covering up an unused door completely with several layers of plasterboard and eliminating and gaps round the edges. For soundproofing you need mass, the more mass the better. Putting a rockwool panel on the door will reduce sound transmission slightly, but probably nothing like the level you'd hope.

Without treating the room as a whole and considering all the areas that need to be soundproofed, you could spend a lot of money and not achieve very much. In most instances, a room within room construction will be the best way to achieve a high level of soundproofing, but it obviously has a big effect on the size of the room.
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Re: Cheap acoustic panels from China/Hong Kong

Postby Elephone » Wed Nov 14, 2018 7:27 pm

Thanks. I presume used and discarded double-glazing panels aren't sold on or disappearing off skips to use as insulation for good reason? Isn't a vacuum even better than mass?
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Re: Cheap acoustic panels from China/Hong Kong

Postby Wonks » Wed Nov 14, 2018 7:31 pm

Vacuum is, but there's no vacuum in a double glazing panel, at least not standard double glazing panels. Put a one bar (100kPa/14.5psi) pressure difference across a large flat sheet of normal glass and it's not going to last long.
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Re: Cheap acoustic panels from China/Hong Kong

Postby Elephone » Wed Nov 14, 2018 7:33 pm

Oh. I thought that's why double glazing looks like it bends inwards. Supposed to be a vacuum or inert gas filled panels. Thanks
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Re: Cheap acoustic panels from China/Hong Kong

Postby Sam Spoons » Wed Nov 14, 2018 7:38 pm

Domestic double glazing never has a vacuum between the panes, just air at normal pressure. The only slightly clever bit is that they use a desiccant to remove any remaining moisture in that air after the unit is sealed.

Lots of articles and threads dealing with the subject, these will do to be going on with.

https://www.soundonsound.com/techniques/practical-soundproofing

https://www.soundonsound.com/forum/viewtopic.php?f=24&t=63522&p=574791#p574791

https://www.soundonsound.com/forum/viewtopic.php?f=24&t=43047
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Re: Cheap acoustic panels from China/Hong Kong

Postby Wonks » Wed Nov 14, 2018 7:51 pm

Often double glazing is filled with dry nitrogen as the molecules are bigger than oxygen and so escape less through very small gaps (why some tyre places will fill your tyres with nitrogen to keep them at full pressure longer). It helps stop water from entering the space and causing condensation between the panes when it's cold outside.
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Re: Cheap acoustic panels from China/Hong Kong

Postby Elephone » Wed Nov 14, 2018 8:23 pm

Well, I can't find anything cheaper than this, even to pick up in person. It says the 50mm thickness option gives me 9 slabs of 600mm x 1200mm giving 6.48m2 for £28.99 free P&P.

Does this sound like a reasonable deal? Thanks

https://www.ebay.co.uk/itm/ROCKWOOL-RWA ... 2183154243?
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Re: Cheap acoustic panels from China/Hong Kong

Postby Sam Spoons » Wed Nov 14, 2018 9:24 pm

That's similar to what I used, mine was RW3 which is 60 g/m3 as opposed to RWA45's 45g/m3. The RWA45 will work pretty well as acoustic treatment but, despite what the manufacturer says, It will be little or no use for 'sound proofing'.
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