PI Audio Group Diffusers

sl_1800 · « **Reply #140 on:** 26 Jan 2011, 09:10 pm »

Four feet wide

, that is big, your right in the pic it looks much smaller.

Quote

Behind the trapezoid are 3 different tuned traps and a fairly dense fill of fiberglass.

Could you expand on the 3 different tuned traps?

dBe · « **Reply #141 on:** 27 Jan 2011, 01:53 am »

Quote from: sl_1800 on 26 Jan 2011, 09:10 pm

Could you expand on the 3 different tuned traps?

I cut some sonotube (quarter wave traps) to get the second and third bass harmonic in the corner and built a helmholtz resonator tuned to the floor to ceiling mode. I'm not really sure how well it worked due to them being inside another cavity and certainly not at the optimum placement for them, but the bass in the room is very, very good. It is just beyond my measurement capabilities. Also, the ugly bookcase is an impediment to high functioning trapping.

The remodel will take care of all of those issues.... maybe.... someday....................

I thought I would have all of this free time being my own man and all. Who knew?

Dave

TomS · « **Reply #142 on:** 28 Jan 2011, 03:34 pm »

Quote from: dBe on 27 Jan 2011, 02:02 am

Flat paint will retain some of the HF absorption characteristics of the foam. Gloss will make them pretty reflective for a brighter top octave. Eggshell seems to be the best compromise. It sounds open, but not bright. Two coats sprayed with an airless or rolled with a small foam roller works very well.
...

Dave,

I'd like to try some of these but still am not clear on the paint options

. In terms of absorption, it just seems the thickness/depth/hardness of coating would make more difference than whether it is shiny. In my case I would need a bit of absorption, so maybe 2 coats of flat make sense. So if you want to pay for pre-paint, you just tell Greg whether you want flat, eggshell, or gloss and he lets her rip with 2 coats? The sealer is double the money, so what are the advantages of doing that vs what you described above?

If I wanted to paint it myself, is the mini-roller method a pain to do? Unfortunately, I don't have a sprayer.

Could you do a progressive set of coats to see the effect, knowing there you can't then go backwards. i.e. start with the most absorption (flat), then add coats to make it more reflective? Is there a point of too much paint on it?

Sorry, I be dense

Tom

jtwrace · « **Reply #143 on:** 28 Jan 2011, 03:37 pm »

Quote from: TomS on 28 Jan 2011, 03:34 pm

Unfortunately, I don't have a sprayer.
Tom

You could purchase an inexpensive airless sprayer. Not much money and will work very well for this application.

TomS · « **Reply #144 on:** 28 Jan 2011, 03:42 pm »

Quote from: jtwrace on 28 Jan 2011, 03:37 pm

You could purchase an inexpensive airless sprayer. Not much money and will work very well for this application.

I know, but it's just too darn cold to be spraying paint

jtwrace · « **Reply #145 on:** 28 Jan 2011, 03:45 pm »

Quote from: TomS on 28 Jan 2011, 03:42 pm

I know, but it's just too darn cold to be spraying paint

I thought everyone had an air conditioned / heated garage like me.

TomW16 · « **Reply #146 on:** 28 Jan 2011, 04:16 pm »

I also use my garage as a spray booth and it seems that my timing sucks every year. I build something in the fall/winter and have to wait until spring when the weather warms up to finish it.

Tom

dBe · « **Reply #147 on:** 28 Jan 2011, 04:21 pm »

Quote from: TomS on 28 Jan 2011, 03:34 pm

Dave,

I'd like to try some of these but still am not clear on the paint options . In terms of absorption, it just seems the thickness/depth/hardness of coating would make more difference than whether it is shiny. In my case I would need a bit of absorption, so maybe 2 coats of flat make sense. So if you want to pay for pre-paint, you just tell Greg whether you want flat, eggshell, or gloss and he lets her rip with 2 coats? The sealer is double the money, so what are the advantages of doing that vs what you described above?

If I wanted to paint it myself, is the mini-roller method a pain to do? Unfortunately, I don't have a sprayer.

Could you do a progressive set of coats to see the effect, knowing there you can't then go backwards. i.e. start with the most absorption (flat), then add coats to make it more reflective? Is there a point of too much paint on it?

Sorry, I be dense

Tom

You not dense - you inexperienced!

The gloss paint has more of an ability to bridge the micro pores in the foam - That is why it is more reflective. The sealer is more of a hard shell and is a wee bit more ding resistant, but 100% reflective and only good for some applications.

The mini-roller is a PITA, but can be done. Spraying is by far the best method - or have Greg paint them. Behr paint has a huge color palette

Looking at your room I'd say that eggshell is what you would want - you have the absorption thing,, er, uhm... covered (as it were

) I don't think you would have to worry about too much paint, but on the appearance aspect alone I think gls is kinda cheesy looking unless you need the reflectivity.

Dave

dBe · « **Reply #148 on:** 28 Jan 2011, 04:22 pm »

Quote from: jtwrace on 28 Jan 2011, 03:45 pm

I thought everyone had an air conditioned / heated garage like me.

The catalytic propane heater is the best thing since sliced bread for us pikers.

Dave

TomS · « **Reply #149 on:** 28 Jan 2011, 04:41 pm »

Quote from: dBe on 28 Jan 2011, 04:22 pm

The catalytic propane heater is the best thing since sliced bread for us pikers.

Dave

Let's see... a spray setup, a heater, and oh, maybe a spare garage, to save a c-note for painting. That's the kind of tool envy for no return that causes even my very tolerant wife to question it

TomS · « **Reply #150 on:** 28 Jan 2011, 04:47 pm »

Quote from: dBe on 28 Jan 2011, 04:21 pm

...
Looking at your room I'd say that eggshell is what you would want - you have the absorption thing,, er, uhm... covered (as it were ) I don't think you would have to worry about too much paint, but on the appearance aspect alone I think gls is kinda cheesy looking unless you need the reflectivity.

Dave

Yeah I do have a lot of trapping, but my room looks a little different at the moment. I put up a 103"x61" laminate surface projection screen 2' out from the front wall to try a HT setup. Soooooo, I have this big flat hard reflector hanging there that rings like a bell, besides being reflective. I was thinking about damping the back of the screen with something light (I have some no-rez) and then hanging four of the 2x4 ABB's on the front for music listening. They're light enough I could move them off for movies quite easily. What do ya' think?

jtwrace · « **Reply #151 on:** 28 Jan 2011, 04:50 pm »

Quote from: TomS on 28 Jan 2011, 04:47 pm

Yeah I do have a lot of trapping, but my room looks a little different at the moment. I put up a 103"x61" laminate surface projection screen 2' out from the front wall to try a HT setup. Soooooo, I have this big flat hard reflector hanging there that rings like a bell, besides being reflective. I was thinking about damping the back of the screen with something light (I have some no-rez) and then hanging four of the 2x4 ABB's on the front for music listening. They're light enough I could move them off for movies quite easily. What do ya' think?

I think it goes something like....it didn't happen without pics.

TomS · « **Reply #152 on:** 28 Jan 2011, 04:54 pm »

Quote from: jtwrace on 28 Jan 2011, 04:50 pm

I think it goes something like....it didn't happen without pics.

Hey, I'm workin' here today... screen is still in progress, not trimmed out yet

Use your imagination!

dBe · « **Reply #153 on:** 28 Jan 2011, 05:12 pm »

Quote from: TomS on 28 Jan 2011, 04:47 pm

Yeah I do have a lot of trapping, but my room looks a little different at the moment. I put up a 103"x61" laminate surface projection screen 2' out from the front wall to try a HT setup. Soooooo, I have this big flat hard reflector hanging there that rings like a bell, besides being reflective. I was thinking about damping the back of the screen with something light (I have some no-rez) and then hanging four of the 2x4 ABB's on the front for music listening. They're light enough I could move them off for movies quite easily. What do ya' think?

I think that sounds like a stellar idea. Damping the resonance of a flat panel like that is a great idea, too. Remember it will ring at the frequencies determind by its' dimension pluse those harmonics, sums and differences. Damp that BigBoy.

Dave

jtwrace · « **Reply #154 on:** 28 Jan 2011, 05:18 pm »

Quote from: dBe on 28 Jan 2011, 05:12 pm

Damp that BigBoy.

Dave

That just doesn't read well to me.

TomS · « **Reply #155 on:** 28 Jan 2011, 05:30 pm »

Ask and ye shall receive... Maybe this goes in acoustics or HT circle, but I was most interested in the ABB's for the front. With the 80/20 frame it's very easy to do a temporary clip on arrangement and since they're so light no worries to just pull them off for a movie. Any ideas for damping those 3 areas on the back of the screen without making it weigh a ton would be welcome too.

jtwrace · « **Reply #156 on:** 28 Jan 2011, 05:35 pm »

Where are the M-60's hiding?

TomS · « **Reply #157 on:** 28 Jan 2011, 05:37 pm »

Quote from: jtwrace on 28 Jan 2011, 05:35 pm

Where are the M-60's hiding?

I moved them because I didn't want to drop the screen on them during installation

And while they sounded incredible for movie dialog I don't really want to use burn up the tubes for it. They are also quite the light show in a dark room

Not good for movies though.

TomS · « **Reply #158 on:** 28 Jan 2011, 05:45 pm »

Dave,

I should add I wondered about just mounting the ABB's to a 1" 703 sheet which might totally solve the problem from the front side of the screen. They start to get heavy though for simple removal and re-install.

Tom

dBe · « **Reply #159 on:** 30 Jan 2011, 02:52 am »

Quote from: TomS on 28 Jan 2011, 05:45 pm

Dave,

I should add I wondered about just mounting the ABB's to a 1" 703 sheet which might totally solve the problem from the front side of the screen. They start to get heavy though for simple removal and re-install.

Tom

Tom, 703 or ductboard would work well I think. It wouldn't be that heavy if you stayed with 1" thickness. Screens are a challenge, huh?

Dave