New Basstrapdesign - please give me your thoughts

[singer recording]

Hi,

I'm new on this forum, this is my first post.

First I will introduce myself.

I like music and I'm very much interested in good sound quality. As a hobby, together with some friends, we run a Jazz club in Belgium : :: De Singer :: A Jazz Experience :: Rijkevorsel ::.
The last two years I have recorded all the concerts. I got all my information for buying stuff on Gearlutz.

So many thanks for all the information.

I'm ready for my next step in my hobby. I would like to master and edit my own recordings.

For that I need a good room. So I decided to make myself some Basstraps. So if you are interested I would like to hear your comments.

I think I used a knew approach to achieve result.

I did not find a similar solution on this forum. The main difference is the horizontal layering of rock-wool off different densities in combination with a vertical slab of glass-wool,to benefit the most.

I attached a drawing of my design.

I'm looking forward to hear your comments.

Best regards

[avare]

Originally Posted by singer recording

I did not find a similar solution on this forum. The main difference is the horizontal layering of rock-wool off different densities in combination with a vertical slab of glass-wool,to benefit the most.

Welcome to Gearslutz!

There is no acoustic advantage to combining different densities of absorbent material. For thick (12"+)basstraps use regular wall insulation filling the space.

Full of it, nicely,
Andre

[singer recording]

Hi André

thanks for your comment.

There are so many different types of rock-wool.

It ranges from : 40kg/m3 - 45kg/m3 - 55kg/m3 - 70kg/m3 - 100kg/m3 - 140kg/m3
from very stiff to very flexible - with acoustic aluminium foil or without
special acoustic panels : Sono - Sono Duo

I can't find anywhere a decent explanation about the acoustic effects of the density.

There must be a difference - can you recommend a specific type

It's a big job - so I only will start after I had some confirmation about what I'm planning. There is no room for trial and error.

anyone else with good advice?

Thanks,

Kris

[PaulP]

Originally Posted by singer recording

It's a big job - so I only will start after I had some confirmation about what I'm planning. There is no room for trial and error.

I think this is a bit optimistic. There are so many variables, so much interaction
between them, so many opinions based on insufficient information (not to
mention personal beliefs) that there is no way to accurately predict what
effect any part of your treatment will have.

Often the best way to see what effect something will have is to go ahead
and do it. If it doesn't perform as expected you will still have gained knowledge
that will help you progess toward your goal. Often you can make a temporary
treatment that embodies the essence of what you want to do without spending
much time on final looks. For example, there is not much difference acoustically
between a bag of insulation propped up in a corner and a nicely made corner
absorber.

Paul P

[avare]

Originally Posted by singer recording

There are so many different types of rock-wool.

I can't find anywhere a decent explanation about the acoustic effects of the density.

There must be a difference - can you recommend a specific type

It's a big job - so I only will start after I had some confirmation about what I'm planning. There is no room for trial and error.

The thread is long, but it is the best I know fro describing the relationship between gas flow resistance and and sound absorption. Yep, gas flow resitance is what we deal with with insulation, not density.

[Gas flow properties.

Go for the lightest insulation you can get.

anyone else with good advice?

What I wrote to you is not good advice, it is correct information.

Correctly,
Andre

[singer recording]

Hi Andre & Paul,

I got the message.

Less dens is better ?
The thicker the better?
The form of the traps is not that important?

please correct me if my conclusion is wrong.

That is good news to my ears.

The lightest material I know of is Sheepwool : +/- 21kg/m3 - see attachement.

It's nice to work with - it has a lot more elasticity - spring - no dust while working with it.

It has no bad effect on your health.

It's a little bid more expensive than Rock-wool.

So it all comes down to find a nice and aesthetic way to keep it in position?

If you think my conclusion is correct I will start designing a nice way to give it shape.

I wonder if it is important to leave a gap between the walls and the basstrap or is it better to connect completely with de side walls.

Please have a look at the drawing attached.


so many thanks,

Kris

[PaulP]

That looks ok though you should also add some panels to the side walls and
ceiling to absorb early reflections. The wool is fairly light so thick is good.

I suggest you get yourself a copy of Room EQ Wizard (REW) and run a test
after you add each stage of treatment. Then you'll be able to see the effect
each stage has and you'll be better able to judge what might be needed next.

REW Help Page
Home Theater Shack - REW forum.

Paul P

[avare]

Originally Posted by singer recording

Less dens is better ?
The thicker the better?
The form of the traps is not that important?

please correct me if my conclusion is wrong.

You are correct for bass traps.

So it all comes down to find a nice and aesthetic way to keep it in position?

If you think my conclusion is correct I will start designing a nice way to give it shape.

I wonder if it is important to leave a gap between the walls and the basstrap or is it better to connect completely with de side walls.

Have fun! A gap is a substitute for having material in that space. If you gap, use a denser material to get the same gas flow resistance as having the entire space filled with insulation.

Ahah! The gas flow resistance is starting to make sense, isn't it? The end result is the same more or less. Denser at high velocity and a gap, or lower density with no gap.

Andre

[singer recording]

I Have found sheep wool with a density of 15kg/m3.
So this should work very well?

With my new design in mind a will be using 6m3 wool for 4 bass-traps in a 56m3 room.

I will post my drawings in a few day's. (My holiday ends)

http://www.sheepwoolinsulation.ie/do...I_Brochure.pdf


Paul it is for me impossible to register on the website to download the room EQ wizard.

I tried a few times but they don't send me a confirmation registration e-mail.

Is there an other way to get access to the software?

Thanks,
Kris

[R_O]

Hai singer recording,

You're PDF's are a bit nasty to read (online). Might want to post images directly here on the board...

having said that; your first design looks good. you've already got comment from Andre about densities, you're in good hands with him. But, just buy the "regular" stuff you can get everywhere and comes the cheapest. Don't bother too much about densities.

don't forget to add a "screen" to act as a low-pass filter or you MIGHT end up with a room that's out of balance; too much low vs high. The absorbing material willl suck highs and lows.

[PaulP]

Originally Posted by singer recording

Paul it is for me impossible to register on the website to download the room EQ wizard.

I tried a few times but they don't send me a confirmation registration e-mail.

Is there an other way to get access to the software?

That's odd since all you have to do is become a member of the Home Theater
Shack. Maybe your spam filter is stealing your email ? Otherwise I'd contact
the site administrator.

Paul P

[singer recording]

I' m definitely going to use the real wool. Today I received a sample.

It looks feels smells wonderfully - big contrast with rock or glass wool.

It is possible to by the wool not fabricated by the m3 - just the base product before they turn it in to plates or roles. It must be cheaper - I don't know the price yet.

The advantage is less cut fibres - only long fibres - so less dusty and you can put in any shape you like in any density you like.

How do I post images and PDF's directly on the board?

I want to show some pictures of the room I want to transform.

[legezer]

Nobody has mentioned Helmholtz

if you measure to discover the problem frequencies (a real test on the room with a swept sine wave and a measurement mic is going to give you a better picture than going by the room measurements)
then you can make a front panel with slats or holes to make the box tuned to those frequencies

then the more insulation you put in the box the lower the q (the broader the response)

and the front panel gives you dispersion as well

[singer recording]

Pictures of the room I want to transform added, drawing basic design added. The bleu shape on the floor is the size of the bass trap.

I will start of with the 4 corner bass-traps. I designed a complete open structure (48 cm thick) that I will fill up with the wool, the density I can decide myself.

It is possible to play with the grills in front or behind the bass trap - more open/closed - more reflective/absorptive - this will be the next step.

I'll start of with a complete open front and then I will do the first measurements.

I can by 100 kg (+/- 6m3) real wool cleaned & treated with borax for 250 euros.

suggestions are welcome.

[PaulP]

Your traps look good. You'll almost certainly need some absorption and/or
diffusion panels on the walls and ceiling to cut down on reflections. They
look great but they're awfully smooth and shiny.

Good idea to test after each step.

Paul P

[singer recording]

I used Fuzzmeasure (didn't manage to register for EQ room Wizard) to run a test on my listening position in the living room. I don't exactly know how to interpret the results but I think this isn't to bad or is it?

As microphone I used a DPA4061

To test my room I want to tune I need to organise some full range speakers. I have some focal twins for in that room but they only go down to 40 Hz.

Is it important to use full range speakers to measure a room?

What are the best settings in Fuzzmeasure to run a decent test?

Thanks again for good advice,

[rlantis]

Originally Posted by singer recording

I Have found sheep wool with a density of 15kg/m3.
So this should work very well?
Thanks, Kris

Check out this good reference:
http://www.bobgolds.com/AbsorptionCoefficients.htm
thumbsup

[singer recording]

I wondered if this will make a good diffuser.
I have a lot cardboard tubes - diam +/- 60 mm - length : 900 mm.

Will it work if I arrange them like shown in the drawing?

Is the distance to the wall important?
Is is better to place the tubes against each other or just closer to each other?

[Tube Trap Guy]

Building a good bass trap that won't overdamp the high frequencies is more difficult than one may think. And when you are done you have in your hand a one trick pony. Check out [url removed] and you will find everything you need and you won't have to itch after spending two days trying to build something that will work half as well!!!

Chris Klein
Acoustic Sciences Corp
chris.k@acousticsciences.com

[avare]

Originally Posted by Tube Trap Guy

Building a good bass trap that won't overdamp the high frequencies is more difficult than one may think.

Welcome to Gearslutz Chris!

Many people who give knowledge here are experts from araound the world, and their advice is more appropriate to construction and acoustic effects than you think.

Andre


p.s. Most people involved in the thread know that the absorbemt material being discussed is sheepwool, which does not cause major itching.

[jayfrigo]

Originally Posted by Tube Trap Guy

Building a good bass trap that won't overdamp the high frequencies is more difficult than one may think. And when you are done you have in your hand a one trick pony. Check out [url removed] and you will find everything you need and you won't have to itch after spending two days trying to build something that will work half as well!!!

Chris Klein
Acoustic Sciences Corp
chris.k@acousticsciences.com

Hi Chris. Please expand upon the problems you see, and the solutions you might suggest. This is a board for discussion, and we'd love to have your input.

[DanDan]

Hi Singer, many of us are a bit afraid of Rockwool and even more so of Fibreglass. However experience and this link helps us sleep easier at night. The Comparative Safety of Rockwool, Fiberglass, and Organic Fibers (a review)

FuzzMeasure, see my Room Analysis Primer V2, and of course the FM Manual! Your Frequency response looks not bad at all for a start. Your speakers seem fine. However did you drive one or two speakers, and how many locations? The Waterfall needs some adjustment, try a 600mS or even longer Duration. The long booms should tail away to nothing. By nothing I mean try -45 or
-50dB. I am not at all sure you need so much Bass Trapping. All those wooden panels are Bass Traps. As PaulP pointed to, there must be horrendous flutter echoes in there with all that shiny surface. Have you a plan for that?
Also, it is generally understood that speakers should fire lengthways, i.e. into the long dimension.
This places the back wall further away. Overall, I suggest that you visit RealTraps.com and GIK.com to read the articles about room set up and treatment.
And of course, welcome to GearSlutz!

DD

[singer recording]

Hi,

To keep you all informed I posted some pictures of the basstraps I made.

I made 8 inox baskets and will fill them with wool. The baskets are mounted on wheels so I can move them around to get out of the room.

I,m still experimenting how to put the bleu cloth in a fine way and of course I need a lot more sheepwool. But it is all ready obvious that the wool does a very good job.

The next step are some traps against the ceiling and homemade speaker-stands.

so let me know what you think about my solution. Any suggestions are highly appreciated.

[Ol' Betsey]

Those baskets look nice. And seem to keep ALL areas of the trap exposed...

To the guru's: That's a good thing, right?

And I suppose if it damps the high freq's too much you could always cover them with thin plastic before adding the fabric?

What and where do you buy those 'inox' basket containers? Expensive?

R.

[tomdarude]

that looks like a very nice DIY solution! how big are those in the end?? s´they seem quite large, which is a good thing.