22 replies to this topic

[RodN]

Hi all,

I've been working on building some bass traps over the last week and finally got them in place.  A bass trap normally consists of some absorbant material in the corners of ones room. They are commonly placed in the corners as that is where bass frequencies have a tendency to build up. What happens is that if there is build up in the corners they basically act as another source of bass frequencies leading to all sorts of issues within your listening environment.

There are lots of commercial products available to trap bass such as http://www.soundacoustics.com.au/ however I've done a few things differently to some of the commercial products out there.

I have notably left a gap between the trap and the wall. This is based on an excellent article on sound trapping written by Ethan Winer. The principle behind the gap is that traps slow the bass energy down and if there is a trap against a surface it is already travelling very slowly so the trap is at its least effective in that zone.  When there is a gab the material is at its most effective. More can be read on acoustic absorbption here: http://www.ethanwine.../acoustics.html

As I have gone DIY I have also been able to go much much thicker than the commercial products. Their thickest traps are about 120mm deep whereas I've been able to go to 240mm while still retaining the gap descirbed above. This gets the 'real' performance of the trap down to the 50/60Hz zone which is far in excess of the stated performance of the commercial products.

Finally it has only cost me about $150 which is much less than 4m of commercial trap.

Anyway onto the project.

The timber was easy enough to get from Bunnings: http://www.dtvforum....t...ost&id=3492

The backing only required something flexible that would let the air through. It only cost $1 per meter compared to the $10 per meter of the front fabric. No wonder those old ladies go crazy at spotlight when there's a sale on! http://www.dtvforum....t...ost&id=3493

The bases of the frame had to be 240mm to allow for the insulation. Nice and thick! http://www.dtvforum....t...ost&id=3494

Course I neeed two: http://www.dtvforum....t...ost&id=3495

Then to add the insluation. It is understood that a denser material helps. There is a material called corning that has dense fibreglass with a silver backing but I couldn't find anything. The Ethan Winer site notes that rockwool is about as dense as one can get and is pretty much the same thing.: http://www.dtvforum....t...ost&id=3496

The material added in the end took a bit of hunting around and elbowing out of old gypsy ladies to get. It is put on in double thickness and nice and elastic so I could stretch it over the frame. Important to get the colour as colse as posslbe to the walls of the theater: http://www.dtvforum....t...ost&id=3497

So what does it sound like?

In a word "clean". Any hint of wooliness in the bass is greatly reduced. It is very clean and punchy still with alot of detail. I guess it helps to have two whole bags of stuffing in each of the rear corners!

[:)]

hehe you have been busy rod ! hehe elbowing out old gypsy ladies hehe looks looks like a fair effort and an excellent job. you'll have to show us what they look like in the room. good to hear theyre making an audible improvement. and the best part you must be very happy that you made them your self and they didnt cost a bomb as these room treatments tend to do !

[RodN]

alebonau, on Jul 15 2007, 08:17 PM, said:

hehe you have been busy rod ! hehe elbowing out old gypsy ladies hehe looks looks like a fair effort and an excellent job. you'll have to show us what they look like in the room. good to hear theyre making an audible improvement. and the best part you must be very happy that you made them your self and they didnt cost a bomb as these room treatments tend to do !

Yeah thanks Al will take a few shots during the week maybe I didn't have time to get their bases done so will be trying this week.  The good thing with this is that I can build them much thicker than the commercials otherwhise there's a nice convenience factor with the commercial options as they only need staples to get them up on the wall.

[Spearmint]

Wow they look great Rod! I’m sure the improvements far out way the costs and time spent on them.

[norpus]

Fabulous Rod - so good you could diy them so beautifully - I can't wait to hear their effect on your room
Well done!

[JohnA]

Great job their Rod
will be interesting to hear the results myself also, esspecialy after the last little GTG at your place. That setup of yours is just getting better and better

Well done old chap

[Wacko02]

Looks good Rod, but have a couple of quick questions for you.

How are you going to include the gap between the trap and the wall, and how big a gap are you planning?
What type of fabric was used on the front? Nylon or similar stretch material?
How much do these weigh at a guess? (i reckon less than 5 kgs each, but could be wrong).

[Spearmint]

Wacko02, on Jul 16 2007, 11:27 AM, said:

Looks good Rod, but have a couple of quick questions for you.

How are you going to include the gap between the trap and the wall, and how big a gap are you planning?
What type of fabric was used on the front? Nylon or similar stretch material?
How much do these weigh at a guess? (i reckon less than 5 kgs each, but could be wrong).

I think you’ll find the gap is the cut off bit at the back of the trap. I.e. the gap is in the corner as opposed to the wall.

[Wacko02]

Spearmint, on Jul 16 2007, 11:33 AM, said:

I think you’ll find the gap is the cut off bit at the back of the trap. I.e. the gap is in the corner as opposed to the wall.

I thought that might be the case, but wasn't sure if it would be as effective (or the same thing) as having a gap between the wall faces and the trap.

[RodN]

Thanks fellas for the kind words!

Wacko yes there is a gap as you can see the frame for trap is a triangle with its point cutoff. That cutoff point allows for a triangular space between the back of the trap and the corner. The sides of the trap sit flush against the wall. I think the dimensions of the gap are also around the 240mm distances.

The material is open weave nylon that is double thickness to avoid any fibres getting out. I assessed this by blowing through the fabric at the shop to ensure they were open enough to allow air to pass through.  They would weigh between 5 to 10kg's perhaps even closer to 10. I am making stands for them as they are 1.8m high and my ceilings are 2.4m high so the stand will prop them up a little and hold that weight so all I will need at the top is something to stop them falling out (rather than 'hang' them).

[terry j]

very nice Rod

look, have you got a spare few days early October?....   

They certainly look great, even better that they are effective.

[RodN]

terry j, on Jul 16 2007, 08:59 PM, said:

very nice Rod

look, have you got a spare few days early October?....     

They certainly look great, even better that they are effective.

Definitely have mate.  You mean bathurst don't you..? Can't wait and you are welcome anytime if you come down.

[terry j]

RodN, on Jul 16 2007, 09:09 PM, said:

Definitely have mate.  You mean bathurst don't you..? Can't wait and you are welcome anytime if you come down.

Sorry Rod, I guess i wasn't too clear, sigh... I meant I'll go and buy the stuff and whilst you are here......ha ha ha!

I can't wait either quite frankly Mr shankley, looking forward to the tribe descending.

[RodN]

terry j, on Jul 16 2007, 10:12 PM, said:

Sorry Rod, I guess i wasn't too clear, sigh... I meant I'll go and buy the stuff and whilst you are here......ha ha ha!

I can't wait either quite frankly Mr shankley, looking forward to the tribe descending.

heheh no worries mate will be glad to help but not sure....

Q: How many audio nuts does it take to install a bass trap
A: Plenty when you are looking at Mr J's 5m high ceilings!

[terry j]

yeah forgot to ask Rod

seeing as how the buggers are 5m high, you start wondering how high the traps should be??!!  Then you have stability problems (one of them crashing down on your head would bring tears to the eyes).

But, no point in only going (say) 2m high then is there.  Especially given you haven't even approached the top tri-corner.  Then maybe it is so high that it's effects are minimized....

Aahh, the bliss of inaction due to decision paralysis.

[Dlite]

Looks great Rod and a great design.  Is it solidly packed with Rockwool?

[JohnA]

Rod, ever think of starting your own buisiness making these
i'd take a pair  

[Psycho!]

Hmm  I am currently spending over $700,000.00 on my new home theatre.  

hehe most if it will be home,  but there is a big chunk of it downstairs that will be an AV area!

Pic 1

Pic 2

I have been researching the idea of base traps and looked at this material, rather than actually building stuff such as the thread poster.  This stuff from Fonics Acoustics.

http://www.ultrafoni...onic System.htm

I have done a photoshop of a hyperthetical AV area in the actual pic of the finished house, that is exactly what the room would look like when done.  At the moment I have dropped in the Monitor Audio Gold series GS60 [they are at the top of my list at the mo] as well as a mock up of a 65 inch plasma in the alcove...that's basically what the wife and I want and will be happy with,  we decided not to do a dedicated room, that room has been earmarked as a billiard table/bar room!  

Pic 3

Anyway, would such a bass trap material be of any use in the corners of a large open plan area, given that I will be driving such speakwers with some decent grunt for the SPL.  stuff like Musical Fidelity A5, or Nad Master sries, Elecktra gear..would those types of traps do anything or be a waste of time.??  Or is this something that can only be calculated and corrected for when the actual room is done with the speakers in place?  Also do the traps go in every corner or just ones opposite the speakers?

cheers/

p.s forgot to mention the room this gear will be in has 9 foot+ ceilings, if that is something to be taken into consideration as well?

p.p.s..that fonics link ot their main website has some more info.

Over here.

They seem to have good thicknesses in their traps..not as good as the thread poster but pretty deep and wide as well.

[Franin]

Psycho!, on Jul 17 2007, 10:25 PM, said:

Hmm  I am currently spending over $700,000.00 on my new home theatre.  

hehe most if it will be home,  but there is a big chunk of it downstairs that will be an AV area!

Pic 1

Pic 2

I have been researching the idea of base traps and looked at this material, rather than actually building stuff such as the thread poster.  This stuff from Fonics Acoustics.

http://www.ultrafoni...onic System.htm

I have done a photoshop of a hyperthetical AV area in the actual pic of the finished house, that is exactly what the room would look like when done.  At the moment I have dropped in the Monitor Audio Gold series GS60 [they are at the top of my list at the mo] as well as a mock up of a 65 inch plasma in the alcove...that's basically what the wife and I want and will be happy with,  we decided not to do a dedicated room, that room has been earmarked as a billiard table/bar room!  

Pic 3

Anyway, would such a bass trap material be of any use in the corners of a large open plan area, given that I will be driving such speakwers with some decent grunt for the SPL.  stuff like Musical Fidelity A5, or Nad Master sries, Elecktra gear..would those types of traps do anything or be a waste of time.??  Or is this something that can only be calculated and corrected for when the actual room is done with the speakers in place?  Also do the traps go in every corner or just ones opposite the speakers?

cheers/

p.s forgot to mention the room this gear will be in has 9 foot+ ceilings, if that is something to be taken into consideration as well?

p.p.s..that fonics link ot their main website has some more info.

Over here.

They seem to have good thicknesses in their traps..not as good as the thread poster but pretty deep and wide as well.

$700,000!    What equipment are you putting in? What theme are you going to do(Some have done starwars,startrek etc etc). Thats awesome at that price you have plenty of high quality gear to choose from.

[Psycho!]

heh umm the figure was a joke...the house is costing us that much but I refer to the whole house as 'my' home theatre.  

Its the family room we will be putting in the AV gear.  We  have a budget of about 30-35k and we dont go for the 'theme' stuff.  Like I said we are not doing the dedicated room thing, we have dedicated a room for bar/billiards/jukebox kicking back area instead.  Much drinking and merriment in our houses.!

[RodN]

Psycho I think you are better off waiting till everything is in and running as the house has started already. A few sweeps in locations around the room should show where the smoothest bass response is and where the problems are then you can look at treatment.  I think spearmint has a lot of experience with experimentation with that particular product.

[Psycho!]

RodN, on Jul 18 2007, 07:38 AM, said:

Psycho I think you are better off waiting till everything is in and running as the house has started already. A few sweeps in locations around the room should show where the smoothest bass response is and where the problems are then you can look at treatment.  I think spearmint has a lot of experience with experimentation with that particular product.

ok, when you say sweeps, is there some kind of device used to test bass resonances inside a room?  I have a Sound Pressure metre that I used to set up my last HT rig.  There will really only be three corners in this area as it does open out to a much wider open plan design.  I guess I have to expect that I can not hope to attain perfect sonic performance in such a environment, but I do want to maximise it as best I can.  Thanks for the input mate.

Another thing I heard in an interview recently about setting up the sub in the correct position.  This guy, who apparently knows his stuff, was saying that you put the sub in the listening position and then run a section of film etc that you know has good sub usage.  Then you walk arround your room listening to that spot where the sub's performance and output sounds the best to your ears.  It is at that spot you then move the sub to, and apparently accoding to him that will gvie you the 'sweet spot' for subs performacne back at the listening position?  Any thoughts on this process chaps!?

[RodN]

Psycho!, on Jul 18 2007, 08:54 AM, said:

ok, when you say sweeps, is there some kind of device used to test bass resonances inside a room? I have a Sound Pressure metre that I used to set up my last HT rig. There will really only be three corners in this area as it does open out to a much wider open plan design. I guess I have to expect that I can not hope to attain perfect sonic performance in such a environment, but I do want to maximise it as best I can. Thanks for the input mate.

Another thing I heard in an interview recently about setting up the sub in the correct position. This guy, who apparently knows his stuff, was saying that you put the sub in the listening position and then run a section of film etc that you know has good sub usage. Then you walk arround your room listening to that spot where the sub's performance and output sounds the best to your ears. It is at that spot you then move the sub to, and apparently accoding to him that will gvie you the 'sweet spot' for subs performacne back at the listening position? Any thoughts on this process chaps!?

Hi Psycho,

I used the sub in the seating position method for these posts here: http://www.dtvforum....&...st&p=400706

So yes there are methods however these days I'd probably do a spectral analysis as well.  This is a good start but it's only a start. Good sub integration takes some time to get things right. Hopefully spearmint can chime in at some stage he's somewhat of a sub-setup guru and uses very nice equipment to ensure the blend is perfecto!