Turtlerock Forum

Hi all,

have been looking at QRD / PRD diffuser designs and wonder if duplo (or more likely a cheap generic) would be as effective as wood?

Advantage would be much lighter panels and much easier to build.

Probably prohibitively expensive though...

If not Duplo could you suggest another plastic (or lightweight) material that could be easily worked with?

Cheers

After a bit more digging it appears square PVC pipe (with end caps) night be the lightest material. Used by BBC to develop some prototype diffusers in the 90s.

http://www.bbc.co.uk/rd/pubs/reports/1990-15.pdf

Might be difficult to get in small quantities though. Anyone in Bris got a mate in construction?

like this?

http://www.johnlsayers.com/phpBB2/viewt ... =3&t=15106

could look interesting if you matched colors to heights.

yes, exactly like that. Looking at the quantities though it looks like it would be a bit expensive. PVC piping looks like a cheaper option with a similar (light) weight.

Very true, might be able to find some cheap stuff on ebay or at a salvos though

save yourself the hassle and just buy the rpg skylines
they are light ( made out of some kind of polyfoam) and they work
last time i sold some they were @ $160 for two the dollar has changed a lot since then and probably lots cheaper now
you can buy them in melbourne from the acoustivision or i can add my bit to your price and sell them from sydney to you
pretty sure they are stocked up and good to go

dont know about the duplo ones sounds and looks like a night mare in price to me

Yeah the duplo was a case of playing leggo with kids and a connection going off in the dim recesses of my brain.

No cuttting, no measuring, modular and reconfigurable (plus would be a nice talking point).

Doesn't stack up (geddid) price-wise though.

Think it would probably work as effectively as the BBC's use of PVC though - hollow plastic with a reflective surface...

Interesting reading the BBC paper, particularly the section discussing practicalities of fabrication, especially as one of their first preferences, GRP (fibreglass, a thermoset), was scrapped due to the difficulties in laying glass mat into a complex mould and the labour costs involved in attempting same and what was probably the most practical method, thermoplastic injection, which overcomes the issue of complex moulding, was rejected due to the inherently high costs of moulds.

How times/technology have changed...........just as GRP is still inhibited by the costs of hands on labour and the difficulties or impossibilities in forming in complex moulds, thermoplastic injection is still only suited to extremely high volume production due to the cost of the moulds............relatively recently, a product has been developed here in Aust., which is showing the potential to succesfully fill the void between GRP and thermoplastics.

The question I have to ask is...........what would the demand be for modules based on the BBC model and what would be considered a fair price?

Interesting...

DIY in wood / PVC looks to cost about $20 for parts and an hour or two cutting and glueing / drilling.

I haven't heard back from Acoustic Vision on pricing yet but if Rick's right the skyline's are about $80 / panel, maybe cheaper.

I'd pay $40-$50 / panel for something based on the BBC design if you could do it.

that bbc design paper would be interesting if i hadnt read it all before in the rpg diffuser and uses textbook which it has cut and pasted straight out of !
which they of coarse credit so i guess it ok
but it seems to me bbc "design " is exactly the rpg skyline !

why dont you make two out of wood and see how much fun it isnt ?
by then you will know your path

there are some chinese knockoff diffusers hitting my email bin but nobody imports them yet so you would have to buy them in bulk

the rpg foam stuff is pretty unimpressive looking but i have used them several times and they work
they can "flock" them which makes them look even wierder

i might paint mine cream ( they come in stark white )

the cool wooden ones you seek can be ordered but they are $$$



i know for a fact RPG are not bothered by you making your own in a small scale diy effort and they publish the designs in such a helpful way the BBC can make it look like their own research
making them is such a drag after your first couple you would sooner buy theirs if they are available to you i suspect

i think gearing up using that design for mass sale would make issues in countries that uphold their (rpg) rights
and while it seems the market would be big for that kind of stuff
trust me it isnt a commercial concern in the " studio "sector

now your churches and restaurants .. well thats the market that floats

Actually pretty sure the skylines are a slightly different design - but there all based of QRD / PRD design theory. The skylines use PRD while I think the BBC design used a QRD as they found the PRD's didn't work as well in a modular design.

I would think the skylines were superior in many ways - the BBC paper is really only interesting as it's an easy template for a DIY build and they used pvc instead of wood (back to the issue of weight that got me thinking in the first instance). As you mention Rick, the wood build can be a PITA (have tried it before and no fun).

Agree the market is not big enough in studio market to be profitable.

no your wrong dave
that text is straight from dr antonios book including the part apart molding them and the cost effectiveness of the different processes and the polar plots and the number sequence and development of ..
that is all antonio text
most of the book shows not just rpg designs but thousands of words of discussions about the how and why
and plenty of things rpg do and dont produce its more of a text book about diffussers then a sale brochure

the bbc paper is summary of those pages from the much bigger book the dr antonio book

and its heavy book in every sense of the word
i have read it many times so i am sure of the facts
the big book is seriously too mathamatical for my brain but i have a almost photographic memory for the stuff i am interested in
i am interest in skylines

I stand corrected, thanks Rick.

So I guess I should go back to the source.

you certainly dont have to use rpg sklines , but they are a easy solution if you can get them
anything on the roof that breaks up the flat roof to flat floor issue is a goer
i was talking about plastic forklift pallets in another thread
they work pretty well as a roof diffuser and are as cheap as it will get
the whole concept with the skylines is to get an academically random scatter pattern

reality is a different concept to academia

if your busted broke get the small forklift pallets in a couple of different designs
you can even tune them with foam or fibres in the wells which is another idea i stole from dr antonio
he just suggests it might be cool
i have done it - it is very cool

Need diffusers rather than absorbers– from memory the other thread mentioned stuffing pallets with absorptive material? I can see that for a cloud above the mix position both would work. When you say 'little' forklift pallets do you mean the half-size ones that hold fruit etc. or something else?

Money wasn't really the issue to start with - as per my first post it was thinking about diy'ing some diffusers and whether plastic would work as well as wood given the weight involved with the typical DIY builds.

Which book of D'antonio's are you talking about, sounds like a pretty invaluable resource (and I'm of an academic persuasion).

http://www.rpginc.com/book/index.htm

this one is the current combination of a bunch of white papers and everything you ever /never wanted to know about diffusers
the white paper the bbc have used is with in it

the pallet thing is great because they are molded plastic so light and strong and a good depth easy to stick up and some of the molded patterns in them are insane
you can hang them one way and fill them as clouds or the other way and make them diffusers or stuff them partly and make an abffuser ! , there are several sizes
but lots of electrical stuff gets strapped to the smaller ones for ease of movement
think the base of a fridge for example

the only rub is getting the same kind
if you stumble into some that look interesting,
grab them WHEN you see them is my advice !
chances are you wont find that design again dont worry if they are scuffed you can paint them easily
and of coarse if you have a a couple of different sizes and geometries your random factor goes up !

if money isnt an issue just get the skylines they come in two sizes - get a mixture of both

if you are having trouble getting in touch with rpg here in australia
i can sort it for you , i have a good dialogue with them
feel free use my name with acousticvision - it will help more then it harms

oh yes skylines look like they are made out of cheap fruitbox foam
i dont think they are
its probably expensive fruitbox foam

but for the freqs involved that is all that is needed

they photograph much cooler then they look in real life

Apologies if my comments were a bit "vague". I just happen to work as the research and production assistant with the "scientist" who developed the "new" technology I mentioned, and have often thought about making diffusers with our products. The time consuming and costly part is mould design and fabrication, once that is out of the way producing finished product is relatively easy.

always one step ahead of me arent you ausrock

Thanks Rick.

rick wrote:always one step ahead of me arent you ausrock

Well I've been around longer than you so of course I've had a head start

the rpg foam stuff is pretty unimpressive looking but i have used them several times and they work
they can "flock" them which makes them look even wierder

i might paint mine cream ( they come in stark white )

Hey Rick,

if they are a type of polystyrene foam then be careful what type of paint you use as it may dissolve them.

Flocking is the way to go but I'd imagine it would be pretty expensive,

Constructing the wooden variety is very labour intensive and you run into major problems if the timber isn't perfectly square.

Greg Hooke

yeah i understand greg i think they are a fire resistant poly properlyne foam but they still dont like paints with the wrong kind of solvents in them - i am just thinking out loud about painting the ones i have for the studio

i have done a bunch of installs with them and they look great
as long as you dont get too close to them and start
wondering if they are tomato box foam or not !

i have a spray gun so anything is possible

but flocking is a standard on order basis
it gets done in melbourne before they go out - looks weird to me price wasnt too much i think

but flocking is a standard on order basis
it gets done in melbourne before they go out - looks weird to me price wasnt too much i think

If they're just a diffuser it doesn't make a lot of sense why they would be Flocking them as opposed to spray painting them.

Flocking is a process used when you want to retain the absorptive qualities of the product to be treated. It's most commonly used on open cell foams such as Sonex. Big mistake a lot of people make is spray painting Sonex as it closes of the open cell structure thereby reducing it's absorptive nature by a considerable magnitude.

Greg Hooke

they are closed cell hard tight foam of some kind

i think the flocking is made as an option to snazz the colours up
without having people pull out a spray can and ending up with a melted post apolocalptic cityscape from the wrong kind of solvent

either way it is recommended as the way to change the colour by RPG in the states and thats what is done locally

they are amazing boxes that part i am sure of

Quick update - price on Skylines was quoted as $340 / pair.

a melted post apolocalptic cityscape

That's very visually descriptive Rick... you certainly have a way with words.

Greg Hooke

ouch must be old stock pre aussie dollar /us dollar bifo

who would want to be a importer at the moment ?

Ouch indeed.

actually thats about right i just checked some of my invoices
i was mistaken with my first price it was each !
not for two
sorry for the confusion guys

still if you need to solve issues at whatever the price these are the solution