FREE Acoustic Treatment Trial

Anyone who wants to play with acoustic treatment, B&Q are currently selling what are basically 'tube-traps' for £3 each. Buy a couple, stick them in the corners of the room and see if you like the sound. They already have a nice plastic wrap to keep them in shape. If you don't like the sound then take them back for a refund!

If you do like the result, a bit of sewing to fabricate a 'sock' of pretty material will make them pretty.

They are approx, 45cm Diamerter X 1.2m tall.



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Good find! Thanks Simon.

Question for yourself regarding them. Are they likely to absorb specific frequency ranges? If so, any guess as to which that would be, or is room dependent?

 

They should absorb bass and midrange. In a room corner I'd expect them to work down to about 50Hz like most corner bass traps on the market. Just what most domestic rooms need.

 

NIce thinking Tenson. I can vouch that this approach does work; 3 or 4 years ago I designed a secondary shceool ,and for a couple of weeks the 250sq m gym was used for indoor storage of a load of mineral wool batts due on site for use elsewhere - about 30-40cubic. metres worth (in a volume of about 1500cu metres.) Result was obvious - it was where impromptu discussions convened because it had the best speech intelligibility at taht end of teh site at the time. Once removed and the space handed over, it became considerably more lively despite the designed treatment already installed- wall-mounted absorbents, acoustic soffit etc.

And yes, keep the plastic cover in place - it's the limp mass that makes it a useful bass absorber.

 

At £3 a pop, this has got to be worth a try...

 

Haven't been here for a LONG time but....

For a tube trap to work, don't you need to calculate the length and diameter of the trap to effectively 'kill' or reduce the unwanted frequency? I made one years back after searching through google and getting help from a ATC, Acoustic Energy and Wilson USA, and they all told me it was pretty difficult but do-able, but you need to do the 'math'.

The maths was pretty easy BUT the construction is the trap was a very good weekends work. It does work when done properly. I don't believe for a second that buying a couple of rolls of rockwool is actually going to solve anything if anything! You are just p**sing in the wind!

Simon, as a "loudspeaker designer" you should know this....it is pretty rudimentary. It is pretty much like building a box without calculation, for a couple of drive units without knowing their specs, and putting in any crossover in it and hoping it'll work.....

Rob

 

Hi Rob,

I think you are probably confusing resonance based absorbers with porous types. The Rockwool traps suggested here are porus absorbers large enough to work down in the bass range, and putting them in corners helps that too.

 

But you will still need to know exactly what frequency you need to 'drop'. I don't understand what you are recommending people here to do? That they purchase a few rolls of rockwool and what exactly?

Speak to RPG before you recommend anything....OR try this below as this will give you an idea what is 'wrong' or more accurately where your major LF peak lyes.

http://vicoustic.com/VN/Homecinema/

This Vicoustic VariBass system does work and has been mathematically calculated.

Like I said....simply buying a few rolls of rockwool and sticking them in a cormer will do nothing OR make things worse. What if after calculating the absorsion pattern of the rockwool it turns out it will drop 4.5dB at 120hz BUT you have actually have a 58hz issue..... You have now dropped 4.5dB from a frequency that was OK.

Simon, I seriously think you should retract this 'try it' recommendation as it has no logic behind it.

 

He doesn't need to check with RPG or retract anything.
The wool as sold will act as broad band traps and can only bring benefit when used in room corners.

You need to go check the difference between tuned resonators acting over a very narrow band such as the various membrane traps or helmholtz resonators, and board band solutions such as wool and foam.

 

RobM, in your example it might make the bass mode stand out more, but luckily rolls of absorptive material this size will work down to about 50Hz. They won't target one problematic room mode, but they will act to damp the Q of all room modes giving a smoother response and shorter decay rate.

It is the same principle as Auralex and RealTraps bass traps.

 

Off to buy some to try. Thought just occurred to me, is this stuff safe to have in one's listening environment? eg. Safe to breath when used in close proximity, fire hazard.

Cheers,

Nigel

 

Fair question, but there's nothing to worry about. Mineral wool is non-combustible, and safe to handle unprotected. (because the fibres are large- not at all like glass fibre - although the texture is odd and some find irritating, nothing that doesnt simply wash off)

But in this application you dont need to open the pack

 

Thank you, Felix.

This thread must be more popular than first thought. The damn stuff was sold out! AudioSmile members beat me to it. There's another B & Q en route to where we are heading today so will have a look again.

 

I bought some. If anyone in the NW is looking out for the product they have stacks of the stuff at B & Q Warehouse, Bamber Bridge, just south of Preston. It's very bulky. It didn't seem to do anything in my environment when placed in the two back corners, thought it might have made the sound a little darker if anything. My room is terrible on paper for acoustics though, 12 by 11 feet with a seven ft high ceiling. I've covered all the primary reflections with egg box shaped acoustic foam tiles & this seems to have helped the situation. In fact, I had quite a bit more covered than just the primary reflections but had to back off, as it became too dead sounding. I'd have love to have covered everything from tip to toe, just to see how it sounded. I read some article by Ethan Winer, where he said total absorption in small rooms can make it seem as if the room boundaries disappear. My loudspeakers aren't known for prodigious bass so this probably helps as well. Many thanks for the recommendation though.

 

When you say back corners, do you mean the ones behind the speakers? That is where I'd suggest for maximum benefit. How many did you use? I'd have gone for 2 per corner stacked since vertical space is largely wasted.

You won't hear too much difference in tonality, but the bass should seem tighter as faster.

 

Simon

The reason Nigel didn't notice anything is because the idea did not target his problem area - if he has one.

Robholt - the last thing you want to do is do a 'broadband' reduction. Why would you recommend that? Rockwool will not reflect nor diffuse. You are just hoping it will do something..... the something is not always right. The best thing to do is to measure and then treat - not guess!

I sent this thread to a friend at Wilson Audio and he agrees with me. What you guys are trying to do is impossible. Simon, I'm still surprised because as a 'loudpeaker designer' you really should know this - really.

Like I said, I have limited knowledge in this field but it's all on the net and it's not as simple as plonking rockwool in the corners and 'there-you-have-it'.

If you both believe I am wrong, please can you provide the maths based on the properties of the rockwool as well as the dimensions of the packaging.

Rob

 

RobM, you are not entirely wrong. If you have a specific problem with a room mode it can help to measure (or calculate) the frequency and tune a trap to combat it. However, that is not the only way to go about things.

Think about what causes 'bass boom'; resonances between room boundaries. If you use broad-band absorption in the room corners it will reduce the strength of all room modes.

1) The decay rate at low frequencies will be faster across the range.

2) All LF resonances will be reduced in level and have a wider Q (lower and wider resonance). The resonances will merge together achieving a less peaky response.

3) Direct sound will be a greater percentage of the sound at low frequencies.

RPG clearly agree, as they produce a broad-band low frequency absorber

As do Auralex, Advanced Acoustics, Fast Audio and Real Traps from the top of my head.

 

- Re broadband reduction, see Simon (& RPGs) comments

- You say 'Rockwool will not reflect or diffuse'. It will if you open the pack and expose the material, but that is not the purpose here. If you want diffusers, then buy or make diffusers.

- No need to hope. The effects are well understood.

- Of course you should measure and treat, and nobody is saying otherwise. However some treatments have universal benefit in the vast majority of rooms, certainly in the uk.

Have a read of what Ethan Winer has to say on room acoustics. Link below (scroll to 'bass traps') but this neatly summarises the effect of broadband trapping:

http://www.ethanwiner.com/acoustics.html#fiberglass traps

 

I think it's a cool idea.

LF absorption is generally fairly broadband or if it is tuned then normally look for a low Q. The worst room modes are damped more highly than the adjacent frequency ranges (more energy into the absorber for it to work on). You basically end up with a better response overall.

Have to be careful with narrowly tuned absorbers as they sometimes don't work exactly how you want and the problem frequencies can be 'missed' without always knowing it. Also, the LF modal reponse in the medium sized UK rooms can be a bit of a mess so it's normally not as easy as treating one dominant mode.