Bass traps and diffusers

[kags]

FWIW, this thread caused me to find some Owens-Corning 700 series data sheets in my files:

https://groupdiy.com/threads/owens-corning-700-series-fiberglas™-spec-sheets.86166/
I am not an acoustics expert, but have seen/used various combinations in "stacks" for room treatments, gobos, etc. Medium density 703 seems to have been a mainstay.

IIRC, one "stackup" designed by a reputable acoustical engineering firm 40-ish years ago had 2" of 701 facing into the room, then behind it 2" of 703, then 1" of 705 against the wall surface. I may be totally off on the exact thicknesses for each layer after four decades! But I do recall the sheets in the stack.

Bri

Graduated densities are effective because of their impedance changes. I would go more extreme in material variations. Even having one “layer” of air works well.

 

[kags]

This seems to make sense

http://arqen.com/acoustics-101/spea... deep dips in,by the speaker-boundary effect.

Yes- you are taking advantage of space loading and raising the Sbir freq high enough to be mitigated by the wall treatment.

 

[kags]

Btw, which diffusers were you planning on building? The Arqen one seems fairly straightforward though I haven't built it.

For recording spaces I like having large movable gobo type units. Have a deep absorber on one side and then a diffuser on the other. Then you just roll them around and position as needed to get the result you want.

In mix rooms, diffusion can creat problems if it’s too close to the mix position. 10’ is a safe distance for rear or side walls. Space couplers overhead work well with absorbers behind them.

 

[kags]

The REW stimulator is useful but your 0.9 coefficients are too optimistic. The assumption in the simulator is that the entire wall is covered and has that coefficient.

This is another useful tool. You can see that achieving high coefficients under 100 Hz can be challenging. And even then you would need to cover the entire wall at that depth for it to be valid in the simulator.
http://www.acousticmodelling.com/8layers/porous.php

Be sure to check the “random incidence” box. That is more realistic. Also there is a huge margin of error in these numbers, so I treat anything lower than 0.5 as minimally effective.

 

[kags]

Well Jesco said to wrap them in plastic bags and the very thin plastic film is much thinner and he said it would have little to no effect on LF.

That is true in practice. Use the ETC and decay time measurements to verify your results

 

[kags]

Do you happen to have a photo of what your space couplers look like?

I have been thinking of building something for this purpose, and this sounds like a great idea.

There are so many different plans and approaches out there that it is dizzying.

Thanks!

I’ll dig up some photos

 

[kags]

I got a question, would it be better to have all 12 panels at listening height?
For the corners I’m stacking two panels but everywhere else it would seem better to have them all at listening height?

In a mix room First reflections and symmetry will guide you. In a recording space you are free to do anything that gives you good sounding options. Corner traps should at least cover one tri-corner and floor-to-ceiling is even better. Don’t forget corner traps can also go across wall-ceiling corner and you won’t lose floor space.

 

[Spencerleehorton]

Something I’m thinking about is to put the monitors as far back as possible and have the panels in line with them so to have them flush, what’s your thoughts about this?
This would involve having the panels away from the front wall more.

 

[Brian Roth]

Graduated densities are effective because of their impedance changes. I would go more extreme in material variations. Even having one “layer” of air works well.

It's been several years....but I recall trying to find OC 70x sheets in stock anywhere was like finding hen's teeth, unlike it used to be in earlier years (pre-Covid? Supply chain BS?). I need to look again!

Bri

 

[Spencerleehorton]

I will need a fair bit of guidance I think here as there is so much information to look at and need to put together a solid plan of attack

 

[Spencerleehorton]

Just thought it might be useful to describe how the studio was built.
It has one layer of brick then a 2” air gap then another layer of brick, then a 4” stud wall filled with rockwool then 3 layers of plasterboard.
The ceiling has 3 layers of plasterboard and sand within the gaps.
The main room is divided two thirds down and The divider in the room is a 4” stud wall with 2 layers of plasterboard and some plywood over it, filled with rockwool.
Unfortunately I don’t know what density the rockwool is within the stud walls.

 

[kags]

It's been several years....but I recall trying to find OC 70x sheets in stock anywhere was like finding hen's teeth, unlike it used to be in earlier years (pre-Covid? Supply chain BS?). I need to look again!

Bri

It’s easier to find now. As Oz said the acoustical supply houses are overpriced (as is Amazon) but you can special order through Home Depot or Lowe’s. I get that from a commercial HVAC supplier near Los Angeles. Roxul Safe N Sound is avail everywhere, but usually in 16” widths, rather than 24”. Other Roxul (the stiffer/denser ones that Oz mentioned) can be ordered and work well. BTW, the porous absorber calculator website (linked earlier) defaults to 10,000 rays, which is the approx density of Safe n Sound. OC 703 is more like 25,000 rays.

 

[Spencerleehorton]

here are a couple of ideas for the mixing room panel arrangement


which do we think would work better?

or is there a suggestion which could be better?

 

[kags]

Something I’m thinking about is to put the monitors as far back as possible and have the panels in line with them so to have them flush, what’s your thoughts about this?
This would involve having the panels away from the front wall more.

A few inches of airspace behind the panels is a good thing and the speakers can fit in a "hole" in the panels if you like. If the panels start to get close to or flush with the front baffle of the speakers, you may notice a change in the "personality" of the speakers. This is not a good or bad thing, but you may prefer it one way or another. This is not equivalent to soffit mounting the speakers but will change the edge diffraction of the monitors.

 

[kags]

Do you happen to have a photo of what your space couplers look like?

I have been thinking of building something for this purpose, and this sounds like a great idea.

There are so many different plans and approaches out there that it is dizzying.

Thanks!

There is a good thread about space couplers (belive it or not!) on Gearspace https://gearspace.com/board/bass-tr...ness-traps-4.html?highlight=pvc+space+coupler

Here is a photo of space couplers (not my image, but from the thread mentioned above) made from square pvc drainpipe. Again, the dimensions don't matter too much and placing a coupler in front of an absorber increases the efficiency of the absorber by quite a bit in real measurements.

 

[Kelvin Zero]

I have made 12 absorbers which are 100cm x 60cm and are 8” deep with 30kg m3 rockwool inside with cotton covers (dust sheet) I will make about the same for the drum room at 4” thick

This confuses me so much. It reminds me of the time I asked an ex to measure something.
She confidently told me "it is exactly 4ft 39cm long"

 

[kags]

Just thought it might be useful to describe how the studio was built.
It has one layer of brick then a 2” air gap then another layer of brick, then a 4” stud wall filled with rockwool then 3 layers of plasterboard.
The ceiling has 3 layers of plasterboard and sand within the gaps.
The main room is divided two thirds down and The divider in the room is a 4” stud wall with 2 layers of plasterboard and some plywood over it, filled with rockwool.
Unfortunately I don’t know what density the rockwool is within the stud walls.

Are you asking about acoustic treatment or soundproofing? The rock wool in the walls is of no consequence as to how your room sounds.

 

[Spencerleehorton]

Are you asking about acoustic treatment or soundproofing? The rock wool in the walls is of no consequence as to how your room sounds.

Yes I know that I just wanted to give the full picture, the studio is fairly soundproof and we have good neighbours

 

[scott2000]

There is a good thread about space couplers

Came across this while looking...

Getting a big sound from a small room
You can get a big sound from a small room by employing SpaceCoupler panels to achieve loosely coupled spaces, according to Auralex
Acoustics chief acoustical engineer JEFF D SZYMANSKI. He takes us through the principles and applications of this interesting new product.

https://web.archive.org/web/2012042...onmag.com/pdfs/SWEETS~1/bigsoundsmallroom.pdf

 

[Spencerleehorton]

Hopefully we could get back to the original part of this thread please, we seem to be going off pist!!

Need to come up with the best arrangement for my panels