Acoustic Panels and Bass Trapping a new lounge

[playdough]

That membrane is free standing in air, not seal loaded to it's enclosure, more to come on that later

Distortion harmonics of the speakers in play. This might be fun, tame the 21, with environment acoustic control, surface mounted -DL  

Edited August 11, 2023 by playdough

[playdough]

Print up a desktop model skyline diffuser. Have a use for  Half a spool of filament at 10 % infill for 1.

Make 4 into 2 mini diffuser stands for bookshelves  They would end stacked  up 360mm high and 160 wide + hardwood stand. 50mm at it;s thickest.

[DVDHack]

5 minutes ago, playdough said:

Print up a desktop model skyline diffuser. Have a use for  Half a spool of filament at 10 % infill for 1.

Make 4 into 2 mini diffuser stands for bookshelves  They would end stacked  up 360mm high and 160 wide + hardwood stand. 50mm at it;s thickest.

Are you saying the longest 'piece of wood' would be 50mm?

[playdough]

1 minute ago, DVDHack said:

piece of wood

I'll use a hardwood or something pretty 10mm x 30mm x 380mm to make mini stands. Probably glue to the back of the diffuser panels . They are completely printed from filament PLA plastic, no tiny wood blocks

 

[DVDHack]

What I was asking was, what's the longest element sticking out?

[playdough]

Sorry, yea 50mm, highest element. 

 

 

 

Print in white for the first one

Edited August 12, 2023 by playdough

[playdough]

Starting to wrap up this part of the panel job.

Outer case framing made and painted, on the last part, the plaster wall attachment frame/seal,  lovely and sunny today, beautiful. Another coffee before picking up the tape measure.

 

While all that's all going on, the sky line diffuser first section print is coming up and up. Probably be able to look at it finished tomorrow morning. Print looks mint, first base layer went on well, no lifting corners, optimistic. Largest/longest print yet for me yet with this new toy, whole bed area.

[DVDHack]

15 hours ago, playdough said:

Sorry, yea 50mm, highest element. 

 

 

 

Print in white for the first one

You realise that this will only start diffusing at about 3500Hz?

[playdough]

16 hours ago, DVDHack said:

50mm

There are roughly 600 elemental blocks up to 50mm long, 8 x 8mm, 2400 on the completed pair of toy 380mm high skyline diffusers. 

They should have a control range from 3KHz. Not a lot of Sensitivity as they are but only concept model, an embellishment, garnish if you will, shelf trophy  

 

"That, could be scaled up readily to man size" 

 

I've a large timber wall bookshelf that has a little matching veneer  bookshelf/sub system placed discretely as possible, come out really pretty.

 

The diffusers will decorate it, add a touch/look of Audiophile, with all the books. Elegant

 

Little blocks and cutting them is a little bit dangerous to cut, fingers, I like mine. Let the robot extruder do it, safely. 

 

Not everything I make is perceived to be ugly or overcooked. 

 

I am a bass lover, in a new lounge with my Back to the wall, literally, so doing something about that. 

I;m busy.

20 minutes ago, DVDHack said:

You realise that this will only start diffusing at about 3500Hz

 

I don't really care, it's a SCALEABLE CONCEPT MODEL, made 10 times larger, which is do able BTW, I would care. 

Edited August 13, 2023 by playdough

[almikel]

10 hours ago, playdough said:

Starting to wrap up this part of the panel job.

Outer case framing made and painted, on the last part, the plaster wall attachment frame/seal,  lovely and sunny today, beautiful. Another coffee before picking up the tape measure.

 

While all that's all going on, the sky line diffuser first section print is coming up and up. Probably be able to look at it finished tomorrow morning. Print looks mint, first base layer went on well, no lifting corners, optimistic. Largest/longest print yet for me yet with this new toy, whole bed area.

very cool.

What "N" is each panel (how many elements each way)?

Did you use QRDude for the design?

 

Mike

[playdough]

@almikel

Had an idea.

I found a couple of pintables on line.

Cannot understand the language in the summary, but it's flowing and lovely, beautiful looking the drawing out of Engineering yes, there are some numbers, my print is the 18 x 60.  3k to 9.5KHz

I couldn't imagine the time mucking about getting all those little angled various length 8mm blocks sorted out, by hand, after cutting them.

 

Would like to work out how to measure it's sensitivity and bandwidth.

 

It's a cool thing to watch print over 2 days.

 

 

Summary

Diffusori acustici tipo skyline per regie, sale musica e home entertainment realizzati secondo lo schema proposto in questo sito:
http://www.mh-audio.nl/Acoustics/DiffusorCalculator3.asp?km=1.8&kl=6&calc=Calculate+Diffuser#result

I pannelli 18x60 lavorano sulle frequenze ed hanno le dimensioni riportate di seguito:

Calculation Results
Frequency low 2867 Hz
Frequency high 9556 Hz

Diffusor width 21.6 cm

I pannelli 4x Pannello 09x60 dovrebbero lavorare su uno spettro un po' più ampio di quanto riportato perché la colonna minima calcolabile ha base 1 cm di lato mentre i miei hanno 9mm per problemi di ingombro sul piatto ed in più hanno la base superiore inclinata

Frequency low 2867 Hz
Frequency high 17200 Hz

Diffusor width 24 cm

Il file 'Pannello 09x60 cielo inclinato e angoli.stl' è un singolo blocco da 12x12 con colonne da 9mm, alte 60mm come gli altri, col cielo inclinato ed a cui ho aggiunto due blocchi da 15mm di altezza negli angoli per evitare il sollevamento in fase di stampa.

Edited August 13, 2023 by playdough

[DVDHack]

9 hours ago, playdough said:

I couldn't imagine the time mucking about getting all those little angled various length 8mm blocks sorted out, by hand, after cutting them.

You missed the joy of cutting 1872 pieces of lovely Australian hardwood for 12 panels varying from 2cm to 42cm in 2cm increments.  You've replaced that joy with plastic....  

 

 

[playdough]

So as setting up to complete the <100Hz trap install today

Some things have to be considered.

 

Mucking about with large area whole wall structures that are "able to flex quite dramatically". This, within the range of desired treatment.

 

The large timber members in the frames need to become at one and flex with the wall, with each other and not resonate in any way with each other or the structure. All while maintaining a seal to the wall.

 

Thankfully the actual double plaster walls are sound and don't resonate in any way to begin with that's a bonus.

Walls, because of the 2 layer plaster construction ended up quite flat, so run out of a few mm is no problem either.

No calking with any goo, what I'm about to do is absolute  sacrilege to a brand new fitted out lounge room so a little restraint there, no quad around the outside of the frames, asking for resonations. Double sided foam tape, is acceptable, that and 75mm hex head bugle screws is all I'll use.

The panels will go up on the high half of the wall level with the window top arc

 

Skyline print is beautiful, 5 hours to go, chopped through some filament however.

 

Strike a blow, find some studs.

 

[playdough]

8 minutes ago, DVDHack said:

cutting 1872 pieces of lovely Australian hardwood for 12 panels varying from 2cm to 42cm in 2cm increments

I cut enough 90 x 45mm pine studs and noggins to make up for that, don't worry.

 

If I could print houses I'd do that too

[playdough]

There is some wild outlandish rumour getting about, that a pair of older Duntech Princesses might replace the JBL Cinema set, Dunno anything just a rumour

 

Note, they need to be "better" to oust the JBL however. That's another story.

 

Edited August 13, 2023 by playdough

[DVDHack]

1 hour ago, playdough said:

I cut enough 90 x 45mm pine studs and noggins to make up for that, don't worry.

 

If I could print houses I'd do that too

There's a YouTube of some company printing houses with concrete, I think in the US.  Very interesting.

[playdough]

Adding context. 

Might add this to the bass headz play list.

 /

Flexing

 

[playdough]

Been a good day. Progress photos.

 

Graphs and plots. Looking favourable at this stage no denying now you can improve all SPL Harmonic distortion easily with acoustic control . The traps are leaning up on the wall, not installed yet, another set of readings tomorrow after beer o clock.

 

 

Edited August 14, 2023 by playdough

[playdough]

Notes, ToolBox Meeting, gather round.

Today, the core Xhd Polymax bats get chopped up and inserted into the membrane enclosures.

Idea there is to  fill as much of the cavity as possible, but not touch the back of the membrane. Cut to fit the voids and stapled to the frame, so they don't move about over time.

The 5m2 of membrane is already damped by a 20mm sheet constraining Polymax layer directly in front of it  inside the room.

 

The structural reinforcement of the walls has gone well so far, no resonating members, Ended up using a type of rubber door seal strip between the timber members and the wall. If the panels were to come down at a later stage  there would be a few holes to patch, easy, no glue, goo or other nasty stuff to clean off, just a naked plaster no worse for wear.

 

85mm gal hex head bugle screws fix these frames and crush the rubber to 2mm.

1 small runout of some 3mm, will need to be rectified today, on one outer case, before a really neat snug seal can be realised against the plaster of this outer membrane case., forming the full membrane trap seal. Not hoping for an airtight seal, just roughly sealed enough so, if you push on the centre of the membrane, it;ll pop out either side. If all goes well it'll be airtight, very much so.

 

Kind of keen to try it out finished, see weather or not, there is a better less obtrusive and space soaking  of addressing sub 100Hz reverberation that EVERYONE COMPLAINS ABOUT adnausium . When a statement has the word "if" it means there is still an unknown to discover on the journey. Today is a day hopefully some kind of reveal of this almost completed area, I've still 2 more traps to go and it seems a few skyline diffusers to place.

 

The skyline print is mint I can make one every 2 days at a cost of $15 in filament and a $1 in power. To be fair, I just CNBF doing this with thousands and thousands of hand cut and dressed 8mm hardwood wood blocks and anyone who disagrees is a luddite to be fair. Even the internal structure of the print is a hexagonal helix spiral in it's own right so the plastic diffuser to me joins the ranks as a "real deal" 

Feel free to comment.

 

 

 

 

 

Edited August 14, 2023 by playdough

[DVDHack]

58 minutes ago, playdough said:

Feel free to comment.

I thought the enclosure had to be airtight?  I want to do a build but don't want to wall mount so thought I make a sealed box, then I thought I could double up and make it double sided, so there's a membrane front and back with a right 'back' down the middle< thought?

 

As for skyline, you've missed the cathartic nature of the work.  Try making one with a broader frequency range, 3khz is pretty high.

 

1 hour ago, playdough said:

The 5m2 of membrane is already damped by a 20mm sheet constraining Polymax layer directly in front of it  inside the room.

 

I don't understand the construction here.  Isn't the membrane just attached directly over the front?  What is this dampening?

 

Have you found the high density absorption effectively reduces the depth part of the equation?

[playdough]

9 hours ago, DVDHack said:

had to be airtight?

There are 3 main seals to address during this insane experiment.

 

The Wall interface Outer case of the trap seal to the freshly plastered wall

 

The seal will be air tight but would not or intended to hold sustained pressure like a tyre or basket ball,

. There is a cunning plan a foot to jack the outer casing of the frame onto the wall, crush the seal into the wall (control of the seal thickness and gap to wall of 8mm), with a piece of angle iron and a bugle screw. That will be precision. solved a lot of problems,  That's the main interface  of the membrane trap to plaster wall seal. 

 

The outer frame case to membrane frame

 

This membrane frame is a snug recess fit in the assembled on the wall mounting frame, I haven't seen any timber  indicate its not straight enough or mistakes to not get a good seal with  foam core double sided tape on the mating back face of the frame, to the front mounting face of the wall mount frame.

 

The Membrane frame seal to the room

 

The membrane is crushed between the frame and by a pine batten at the perimeter of 40 x 20mm dar. Uesd 50mm plaster screws,  them in deep and often to get a good ol crush seal with the vinyl. 

 

 

 

Otherwise, see attached, the layers in order and build materials for the inner case and outer frame details

12 hours ago, DVDHack said:

absorption effectively reduces the depth part of the equation

There is that, (the actual equasion is above somewhere)  worth investigating, I would believe the heavier the mass of absorb, might work better, not a lot, at 190mm,

In total there is 6 x 20mm layers of membrane (Polymax) damper employed, one is suspended, touching the soft foam face, plus decorative upholstery room inside. An air gap of 70mm then 100mm of poly

 

Low frequencies i'm targeting  maybe in vain, are a interesting beast with a 200mm deep wall panel. It's the whole wall flex suckout at 50Hz and rough to 100Hz, The large wide ranging bass enclosure measures very well outside, saw that for real after I designed and made them.. They have been deployed to venues a couple of times, measured  lumpy response inside this small area.

 

To stiffen a wall you really have to add heavy structure, and 85mm bugle screw some sense into it with intension to raise and dampen the resonant frequency of the wall at 50Hz. Hpoefully improve it a bit.

 

The membrane is quite deliberately positioned all the way across the wall over the new stud sub wall structure, across the boundary corner and  across the other wall to the window. Idea is to short out and damp the walls, with a long limp and damped heavy membrane 5m total over  2 membranes.

 

Full frontal brute force attack the 50Hz approach as I do like my melodic bass to be high and tight.

 

I threw the model out the window and in the unknown.  It was nice to see the results, in the graphs of the work so far. Yesterday was the additional heavy structural frame work, on the wall. No membrane or polymax core on the walls.

 

There is something odly satisfying to a so called Audiophile, about chopping 1200mm x  20 meter spools  one after the other of Polymax and adding it to the walls. 

 

 

 

[almikel]

On 13/08/2023 at 10:15 PM, playdough said:

@almikel

Had an idea.

I found a couple of pintables on line.

Cannot understand the language in the summary, but it's flowing and lovely, beautiful looking the drawing out of Engineering yes, there are some numbers, my print is the 18 x 60.  3k to 9.5KHz

I couldn't imagine the time mucking about getting all those little angled various length 8mm blocks sorted out, by hand, after cutting them.

 

Would like to work out how to measure it's sensitivity and bandwidth.

 

It's a cool thing to watch print over 2 days.

 

 

Summary

Diffusori acustici tipo skyline per regie, sale musica e home entertainment realizzati secondo lo schema proposto in questo sito:
http://www.mh-audio.nl/Acoustics/DiffusorCalculator3.asp?km=1.8&kl=6&calc=Calculate+Diffuser#result

I pannelli 18x60 lavorano sulle frequenze ed hanno le dimensioni riportate di seguito:

Calculation Results
Frequency low 2867 Hz
Frequency high 9556 Hz

Diffusor width 21.6 cm

I pannelli 4x Pannello 09x60 dovrebbero lavorare su uno spettro un po' più ampio di quanto riportato perché la colonna minima calcolabile ha base 1 cm di lato mentre i miei hanno 9mm per problemi di ingombro sul piatto ed in più hanno la base superiore inclinata

Frequency low 2867 Hz
Frequency high 17200 Hz

Diffusor width 24 cm

Il file 'Pannello 09x60 cielo inclinato e angoli.stl' è un singolo blocco da 12x12 con colonne da 9mm, alte 60mm come gli altri, col cielo inclinato ed a cui ho aggiunto due blocchi da 15mm di altezza negli angoli per evitare il sollevamento in fase di stampa.

I can't read Italian either

This photo appears to show 23 elements/wells along the front face...and there's nothing symmetrical...

On 14/08/2023 at 8:21 AM, playdough said:

 

There's a reasonable chance you've built a proper N23 2D Quadratic Residue Diffuser (QRD) 

 

So many "supposedly" diffuser designs aren't based on prime numbers - when they should be to achieve diffusion.

 

Before building another, I would check out QRDude https://www.subwoofer-builder.com/qrdude.htm

It's a truly awesome free tool for designing Quadratic Residue Diffusers (QRDs), and can tell you where diffusion starts/stops and how to optimise diffusion with minimum build depth.

I'm happy to provide assistance - PM me.

 

Awesome 3D print!

 

cheers,

Mike

[playdough]

9 hours ago, almikel said:

3D print

Hi Mike Thanks

Having a look at the simulator, Learning how these QRD's work, very satisfying.

After getting over this little 2 week stint to get the membranes in place will do more with that, as the job progresses into another 2 smaller  membrane traps.

 

The biggest hurdle for me is, being able to generate an Engineering render (file)  that the Prusa Slicer Printer drive program can use to derive tool path/3D Print.

There were quite a few different types of rendered STI files come with the QRD I'm printing now, Larger elements with different height and deflection off set to try for start, for now.

 

 

Lots more REW Measurements and then the job of Digital Impulse Time Delay via Dirac, that's when things get a bit more serious, looking at actual speaker  response correction rather than room harmonics. 

 

 

 

Current print project is for 4 of the 3K/9K Kh  Hz type, 90 hours on the printer, whole print bed, 65mm high ! 2 kg of Filament.

Had 1 print get in 5 hours before some wierd extruder jam, Printer chucked a wobbly and required a Z axis re calibrate, Not all beer and QRD's but happy print 2 is nearly done. 2400 elements  2 to go (5 days print time) 

 

Playdough 

 

 

 

 

 

[playdough]

Something I've learnt the hard way,.

 

Large flat prints like to lift from the printer bed at the corners.  I use a glue stick and put a dab on each corner of the bed plate. Seems to work. First extruder layer bed adhesion is everything.

 

Long duration  printing, keep the room temperature as even as possible, during the print.

When the print is finished let it sit on the bed until room temp. Don't get all keen and separate the print from the print plate even though it is really pretty, while it is all piping hot, the print will warp while you watch it cool.

 

Pop the whole room tamp.  bed plate and QRD print in the freezer for half hour. it will separate itself from the bed plate at "dew point", pop off, slide off if you will, the layer of condensation

 

Dead ruler flat QRD print , nice

[playdough]

Does anyone like maths ?

The maths, starting to develop some  theory as time goes by

 

There is no consideration for surface area of the trap , or near  air tight volumetric air space area application either, weather either are relevant is conjecture.

 

Should the membrane resonant frequency go down as it get's larger or if the air space behind it changes ?

 

The membrane literally stops dead in it's tracks and reflects HF un surface treated as it measures reverb same  like a hard  flat surface, hanging there limp. It's only good for low frequency treatment in this application, narrow bandwidth

 

The mass of absorb within the sealed  air space.

It seems only really there to damp the reaction (widen the Q Factor from resonant Fz)  of the membrane.

 

It's behind the membrane in a soundproof sealed air cavity, where it's actual true ability of treatment say, 1000Hz and up is literally stopped/blocked by the membrane case and back.  It's actual application is  suspension for the membrane so to speak. Widen the Q factor, large surface membrane may be Q Tuneable with the mass damper omission, once things are known.

 

 I am thinking of how the" trap will react, to measurement with regard to reverb response time and what is  it's resonant state reaction when subjected to 20, 30, 40, 50 Hz audio variable tone generator from a good/cool 110dB sub woofer bass speaker, 

 

Only 3 variables, with an outcome of  frequency, mass, depth and 600 are considered, in this particular calculator "accepted as the norm" 

 

 

Playdough