Studio build in Wales, UK...again!

[Gregwor]

Membrane devices can be very effective at target frequencies using minimal depth. The cons with them is that they continue to resonate after initial excitement and they can be difficult to tune. I've never seen or thought of placing a membrane behind a set of hangers but in theory it should work. Maybe John has some thoughts on this as he has developed some crazy rear wall devices and has probably thought of and/or tested something like this in the past!

Greg

[John Sayers]

I've never used panel absorbers on a rear wall.
cheers
john

[Paulus87]

Thanks Greg for your words of optimism... it might be a fun experiment, or an expensive disaster!

I've never used panel absorbers on a rear wall.
cheers
john

Hey John, good to have you back thanks for your words

[Waka]

Hi Paulus,

Have you got a problem you're trying to treat with a membrane absorber, or is it hypothetical?

The reason I'm asking is because, although you have an idea for a massive membrane, it would only be useful if there's a specific frequency you need to target that is high energy at that position.

You might be able to use membrane absorbers back there, but it would be better to measure and create multiple smaller "modules" you could fit in an array in the wall tuned to specific frequencies and areas of high energy.

**** Misremembered research: ignore this, see my next post for details ****
Also you need to stand off any absorption / cloth or treatments at least 6cm from the membrane absorber for it to not negatively affect the device.
***************************

Dan

[Paulus87]

Hi Paulus,

Have you got a problem you're trying to treat with a membrane absorber, or is it hypothetical?

The reason I'm asking is because, although you have an idea for a massive membrane, it would only be useful if there's a specific frequency you need to target that is high energy at that position.

You might be able to use membrane absorbers back there, but it would be better to measure and create multiple smaller "modules" you could fit in an array in the wall tuned to specific frequencies and areas of high energy.

Also you need to stand off any absorption / cloth or treatments at least 6cm from the membrane absorber for it to not negatively affect the device.

Dan

Hey Dan,

Purely hypothetical at this stage, until I measure I won't know if it's needed or not, but it's always good to make provisions for such things... not that I'm hoping to have major problems of course!

Your room is looking great btw, thanks for all the updates

Paul

[Waka]

Also you need to stand off any absorption / cloth or treatments at least 6cm from the membrane absorber for it to not negatively affect the device

Just to correct myself here!

I misremembered what I read in a BBC paper. I have read you indeed need to "stand off" the fabric/absorption from a panel absorber to preserve it's effectiveness, but the 6 thing was to do with a different effect.

The BBC paper was researching the effect of a fabric covering over different absorbers including wide band.

They found there is a marked increase in high frequency absorption if fabric is OVER about 6mm (not cm ) of an absorber surface, if that absorber mainly reflects those high frequencies; they used a perforated panel absorber to illustrate this.

So you have to be careful, if you intend to maintain high frequency energy in your room, by covering a panel/helmholtz/perforated panel absorber or reflective surface in fabric, you can unintentionally, add significant high frequency absorption.

So, what I said in my last post about standing off at least 6cm wasn't correct. The BBC research didn't mention how far away a covering has to be before the additional high frequency absorption is mitigated, but they showed that having it very close to the surface is a good mitigation.

All of which is unrelated to your hypothetical membrane absorber with absorption standing in front of it, apologies! as you have no intention of retaining high frequency energy and instead intend to fully absorb them.

Good reading, that paper, though for those interested:
https://www.bbc.co.uk/rd/publications/rdreport_1981_08

[Waka]

Just to add a little more here. I've found the BBC research that shows that putting a fabric covering over the face of a helmholtz absorber, significantly reduces the helmholtz performance.

Here's the paper:
https://www.bbc.co.uk/rd/publications/rdreport_1992_10

They put their fabric draped loosely in front of the helmholtz and it shows the peak absorption coefficient dropping from 0.95 to 0.7 with very little widening of the frequencies affected. And when they fixed some tissue paper over the face, the affect was severely worsened dropping to 0.4!

So I think you could expect that putting anything that reduces velocity of the air directly infront of a helmholtz will degrade performance.

This is also the paper that they design their great A10 general purpose very low frequency membrane absorber in.

So for you Paul, this won't really affect your membrane wall idea, as long as the hangers are not touching the wall. But will probably affect if you put a slat wall behind your hangers.

Dan

[Paulus87]

Just to add a little more here. I've found the BBC research that shows that putting a fabric covering over the face of a helmholtz absorber, significantly reduces the helmholtz performance.

Here's the paper:
https://www.bbc.co.uk/rd/publications/rdreport_1992_10

They put their fabric draped loosely in front of the helmholtz and it shows the peak absorption coefficient dropping from 0.95 to 0.7 with very little widening of the frequencies affected. And when they fixed some tissue paper over the face, the affect was severely worsened dropping to 0.4!

So I think you could expect that putting anything that reduces velocity of the air directly infront of a helmholtz will degrade performance.

This is also the paper that they design their great A10 general purpose very low frequency membrane absorber in.

So for you Paul, this won't really affect your membrane wall idea, as long as the hangers are not touching the wall. But will probably affect if you put a slat wall behind your hangers.

Dan

Thanks for the clarifications and information Dan

[Paulus87]

Hi Guys,

I have a lot of pics of my progress but can't seem to upload them on here despite me trying for an hour or so! I just can't get the size and format right...

Anyway for those of you that are interested I've uploaded them all in albums on my studio's facebook page:

www.facebook.com/nightowlstudios.co.uk

That'll have to do for now as I am too tired to keep trying to upload them here, I'll have to try again another time.

Here's what I've done since my last major update:

- Concrete is now poured into the compartments between the wiring conduits. This was such hard work as all the perimeter walls were already in place so tamping and levelling proved to be very fun. It was worth it though, the concrete is over kill at between 7" & 9" thick, but that's what it took to get the ground level and also provide enough depth for my wiring conduits. An 6mm underlay with DPM and laminate floor will go over this.

- Finished off more framing by installing rafter and collar ties as well as some cross members between the studs as well as new door frames. The door frames are solid with 1 jack stud & 2 king studs per side plus an over sized header and horizontal supports. The incredibly heavy doors hang and swing nicely with a sub 2mm gap around the perimeter. Still need to install the seals and trim as well as the automatic door closers.

- Sealed every single seam, gap, crack, hole and joint with acoustic caulk. This took hours and around 80 tubes of caulk, I really do not wish to see another tube of the stuff again though will have to when I start work on the other rooms. My wife helped out with this which cut the time in half, but still took ages.

- Started insulating the stud bays/ceiling. I'm using Isover light fluffy as this is just to line the bays behind the rest of the treatment which will consist of mostly hangers and deep broadband traps on the side walls.

Now I have a questions where I could use some advice:

I will cover the insulation with Dacron and then some very cheap fabric and leave it as is for a while until I am ready to buy/build the majority of the acoustic treatment. I have some very breathable cotton dust sheets which I bought from new which have a thin plastic layer attached on the back (to waterproof it and stop paint dripping through when used to protect stuff while decorating)

I would like to use this fabric just to cover the walls and the ceiling for now to make the space a little more presentable. I know the acoustic effects of thin plastic but how about the risk of condensation? Do you think it would be a bad idea to cover the entirety of the space with this plastic backed fabric? am I asking for condensation problems?

Many thanks,
Paul

[Gregwor]

I have a lot of pics of my progress but can't seem to upload them on here despite me trying for an hour or so! I just can't get the size and format right...

I can't advise how to resize on a windows computer as I'm an Apple user, however there is a super powerful free program called Gimp you could try to use to resize if you're on a windows computer. On an Apple computer, open the picture in Preview and then go to Tools --> Adjust Size and then whatever your largest dimension is (in pixels), type is 1200 and then resave the picture. If the file size is above 500KB, you will need to export it in a smaller file format. I've found that going File --> Export then choosing the file type as JPEG then moving the quality slider just a hair less than full will dramatically drop the file size. After that, hit save and you're ready to upload it to the forum!

Anyway for those of you that are interested I've uploaded them all in albums on my studio's facebook page:

It looks awesome. I haven't fully gone back through your thread to remember your entire design, but I see one of your FB friends brought up a rotting issue. I'm hoping you've considered and sorted that all out?

- Sealed every single seam, gap, crack, hole and joint with acoustic caulk. This took hours and around 80 tubes of caulk, I really do not wish to see another tube of the stuff again though will have to when I start work on the other rooms. My wife helped out with this which cut the time in half, but still took ages.

I quite literally have experienced the countless tubes of caulk pain. I eventually bought a cordless caulking gun to alleviate the pain. It also didn't help that I did it with a recently discovered dislocated wrist

I know the acoustic effects of thin plastic but how about the risk of condensation? Do you think it would be a bad idea to cover the entirety of the space with this plastic backed fabric? am I asking for condensation problems?

Again, I'm not entirely following where you'll be putting this (is this going to be on your final inner leaf insulation or our outer leaf temporarily before you put up your inner leaf? Any plastic needs to be on the cold side of your inner leaf sheathing. This would act the same as your vapour barrier in a regular basement. I hope I've explained that clearly.

Greg

[Waka]

Again, I'm not entirely following where you'll be putting this (is this going to be on your final inner leaf insulation or our outer leaf temporarily before you put up your inner leaf? Any plastic needs to be on the cold side of your inner leaf sheathing. This would act the same as your vapour barrier in a regular basement. I hope I've explained that clearly

I'm not sure about this for the UK Greg. We tend to put vapour barriers on the warm side of the room (just beneath the internal plasterboard) and vapour permeable membranes on the cold side. This keeps warm vapour in the room and not meeting the cold damp exterior air to condense.

Although with inside out designs this design goes all up in the air. The vapour control barrier should go directly against the plasterboard/osb3, without a cavity behind it.

What kind of membrane are you putting on the OSB3?
You could get problems with condensation with another impermeable barrier infront of the insulation.

Dan

[Gregwor]

Dan,

I think we are saying the same thing, just differently. It's 3:30am here right now and after tomorrow I leave on a holiday to Maui for a week otherwise I'd draw something up in SketchUp showing an inside out build to show what I mean. Basically, I'd just be drawing what you did with your personal build though. To try and reword what I meant, the "warm" side of the inner leaf drywall is what you'd paint or hang a picture on. The "cold" side of the inner leaf drywall would have the barrier and then insulation within the cavity of the inner and outer leaves. Does that make more sense? Granted, the barrier would be "warm" since it's on the warm side of the insulation. But I'm not sure how else to word it to say that he shouldn't put the barrier on the exposed side of the drywall

A drawing is worth a million words. I'll ask Siri to remind me to draw it up when I get home from my holiday.

Greg

[Paulus87]

Hi Greg & Dan,

Thanks for your input guys, I appreciate that.

So I am not intending to use plastic backed fabric to be a vapour retarder, more I am just worried it will act as one as a side effect of using the fabric for aesthetic reasons.

Perhaps it would be better to just use different fabric and not risk it.

Greg: regarding the ceiling rotting out, I do not think it will be a problem in my design. What you have seen in the pictures is the inner inside out leaf. As it stands, that's all I have constructed at the moment and I will be building the outer leaf around it at a later date. So not only have I built it inside out, but also in reverse, which is unusual. But the reason for doing so was because I need a functional space (even if it is temporarily not completely isolated) that I can use for mixing and teaching. I cannot currently afford to build all the other rooms of the studio and therefore the outer shell must also wait. By doing the inside first it enables me to get all my gear in and get use out of the space in the mean time.

I also wanted my control room to have as much volume as possible which meant that I needed to do a dual pitched roof with no attic space, and permitted planning in the uk states that a dual pitch roof can be at a maximum height of 4m in stead of 3m with a single pitch roof. that leaves me with the dilemma of how to vent the roof space since both my internal leaf and outer leaf are both dual pitched. So I decided to build it with an unvented design with a warm roof. If the roof deck is insulated above, between and below the rafters then there is no need for it to be vented. It is a newer more efficient way of building, similar to how passive houses are constructed.

From the pictures, can you see any potential problems with anything else or any other suggestions?

Regarding the resizing of the pictures, I too am an Apple user and I did the procedure you described in your reply however I could not get some of them below 500kb which is why they were not uploading, so then I used the jpeg2000 format but that is not accepted on the forum. By that time I gave up as I had so many pictures to upload and it is very tedious uploading them on here one by one! I will get round to it one day, but hopefully most people use facebook and are able to see them on there.


Have a great holiday Greg!

Cheers for now,
Paul

[Gregwor]

By doing the inside first it enables me to get all my gear in and get use out of the space in the mean time.

From the pictures, can you see any potential problems with anything else or any other suggestions?

I totally get your idea and working with your limitations, I think you've utilized the space well.

I too am an Apple user and I did the procedure you described in your reply however I could not get some of them below 500kb

Either:
- slide the quality slider lower until it goes below 500KB
- if for some weird reason it is still above 500KB, save it with the quality as low as it will go and then open it again and try making the quality even less -- again. Basically "stack" the crappy quality haha
- if you can't get decent enough results with the above method, try setting the pixel size to a smaller value such as 1000px, or even 600px.
- if you can't get any of this to work for some bizarre reason, please upload the full resolution pictures to dropbox or something so that myself and/or other members can see if we have any luck.

Have a great holiday Greg!

I SHOULD be in bed right now as it's going to be a long trip with my little kids on the airplane and I didn't fall asleep last night until 7am But, of course I'm up getting in a last minute Sayer's forum sesh! hahaha

Thank you though. I guess I'm leaving at the perfect time because the temperature here is supposed to get really cold this week: (note, I put this picture (730px X 788px)to the lowest quality setting making it ~38KB)

Cold AF.jpg

Greg

[Paulus87]

Hi guys,

The inside is really taking shape now, I've got the main window plus the two side window frames in plus the wall/ceiling corner soffit framing done. All the inside out walls have their bays filled with insulation and I'm ready to install the insulation and hangers in the ceiling.

The challenge is knowing how best to arrange the hangers in a dual pitch ceiling. Here's a really quick diagram of my initial idea; Since I have some simple trusses up there I thought I'd take advantage of the cross members by using them to hang the hangers from as well as supporting some thick fluffy. So the ceiling bays between the rafters will be filled with fluffy, and then the peak in the middle of the ceiling can be filled with fluffy down to the collar tie line, then the large central hangers can be hung from those collar ties, angled towards the speakers.

Since the hangers will be around 8' long and 2' wide that leaves some space around the edges. So I thought I could fill that space with some straight down vertical hangers which would fit between the central hangers and the ceiling corner traps, this is the part I'm not sure about since ideally these hangers would be angled towards the speakers as well but difficult to do so due to the angle of the pitched ceiling. Then finally there would be a layer of fluffy below the hangers down to the rafter tie line, which will be covered in fabric.

Any suggestions?

Paul