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1D PRD calculator? Drum Machines & Samplers
Old 16th September 2011
  #1
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1D PRD calculator?

there are plenty of 2D PRD calculators online (Calculate a Two-Dimensional Primitive Root Diffuser), but im looking for a 1D. i know there is a spreadsheet floating around on one of the expert's sites that frequents this forum, i just cant pinpoint it (John?).

i want to build some 1D high order diffusers out of EPS foam (by hand, since it's something i can do in my condo without having to borrow a friend's garage for the weekend)

doing the well dividers could prove to be quite difficult, and after seeing some amfg reflex modeling of high-order PRDs, they seem to have acceptable performance when finless (vs comparable N finless QRDs).

does anyone have a 1D PRD calculator available by chance?
Old 16th September 2011
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Old 17th September 2011
  #3
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anyone recommend a decent electrical hot-gun to cut through this dense EPS foam? the unit i got from Lowe's has been destroyed after 13 wells :/
Old 17th September 2011
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Old 19th September 2011
  #5
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boggy's Avatar
Quote:
Originally Posted by localhost127 View Post
anyone recommend a decent electrical hot-gun to cut through this dense EPS foam? the unit i got from Lowe's has been destroyed after 13 wells :/
Proxxon foam cutters are pretty decent for me:
PROXXON TOOLS: Hot Wire Foam Cutter
heh
Old 20th September 2011
  #6
Old 22nd September 2011
  #7
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Old 22nd September 2011
  #8
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Old 22nd September 2011
  #9
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Well, u could always look at thistothat...

This to That (Glue Advice)

clue: pretty sure one of the glues they used that worked was a PVA.
Old 22nd September 2011
  #10
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Ct1 or tec7 will work fine
Old 23rd September 2011
  #11
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Anything containing solvents is out. Silicone is nice.
Old 23rd September 2011
  #12
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tec7 and ct1 will not change the polystyrene.

Regarding spray lacquering, due to the extremely irregular surface it is is not worth spray lacquering imo, you will get overspray issues, and paint runs in the well debth.


I have checked this out myself.

Paint overspray in the finish looks like sandpaper...

It is best (fast/easy) to spray them flat, before assembly.
Old 23rd September 2011
  #13
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Quote:
Originally Posted by hsal View Post
tec7 and ct1 will not change the polystyrene.

Regarding spray lacquering, due to the extremely irregular surface it is is not worth spray lacquering imo, you will get overspray issues, and paint runs in the well debth.


I have checked this out myself.

Paint overspray in the finish looks like sandpaper...

It is best (fast/easy) to spray them flat, before assembly.
noted - thank you,

although i shouldn't have many areas of irregularities... the sides of the EPS are all smooth (outer/inner sides of wells). the only places that arent are the tops of the wells (as detailed in the above photos) - but i will be placing strips of hardboard down to function as the well bottom in each well - so everything should be fairly uniform. i'll see how it turns out tonight when i get the hardboard well bottoms glued in place. thank you!
Old 23rd September 2011
  #14
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I guess it depends on what kind of finish you will be satisfied with, the irregularity is in the nature of the qrd design.

When you spray lacquer into cavities the overspray has nowhere to go, and will be trapped.


With low pressure spray technique (hvlp) 30-40 % of the paint will go of the surface and vented out to the filters in the ventilation system, spraying into a cavity the overspray is "trapped".

It is better with air assisted airless due to softer spray pattern, but there is no way one can get a good result spraying into such narrow cavities imo.
Old 23rd September 2011
  #15
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Quote:
Originally Posted by hsal View Post
I guess it depends on what kind of finish you will be satisfied with, the irregularity is in the nature of the qrd design.

When you spray lacquer into cavities the overspray has nowhere to go, and will be trapped.


With low pressure spray technique (hvlp) 30-40 % of the paint will go of the surface and vented out to the filters in the ventilation system, spraying into a cavity the overspray is "trapped".

It is better with air assisted airless due to softer spray pattern, but there is no way one can get a good result spraying into such narrow cavities imo.
now i see what you're saying

thank you - duly noted
Old 23rd September 2011
  #16
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%%%
Old 24th September 2011
  #17
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I suggest using a thick waterbased paint, and brush it on before assembly, having a fam blowing air over the pieces will speed up drying time.

hdf is a good choice.
Old 28th September 2011
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^^^
Old 28th September 2011
  #19
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Another diffuser calculator, including 1D PRD, Sound Splash ... free version is available, it calculates QRD and PRD.
Old 28th September 2011
  #20
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Was between $us200 and $us250 last time I checked. not sure if demo available. It appears as a kind of QRDUDE on steroids and doesn't use BEM to do calcs.
Old 6th October 2011
  #21
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^^^^^^^^^^^^^^^
Old 15th October 2011
  #22
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all ready for paint!



still came out to around ~18lbs per unit. quite solid though - the bulk of that weight is in the caulk!
Old 24th February 2013
  #23
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Old 24th February 2013
  #24
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Quote:
Originally Posted by yphs_mst View Post
Update for the sound splash link:

www.hxaudiolab.com
wonderful - thank you!
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