[Big Red Machine]

You need to calculate how much bow you want.  Plus there is a limit you can expect to achieve.  I used Formica in a stainless steel finish for my poly units.  I would guess they are bowed about 8 inches out. 

You can do a hand sketch and use pi r squared and pi D formulas to calculate eventually the segment length of the curve you would need for x radius with the full center of the poly buried somewhere deep within the wall space and you calculate back.  I know how but obviously cannot explain it here.

Hi John,

What width do the plywood panels need to be if the strips are above referenced distance apart?

Nicholas

[nottaway]

You need to calculate how much bow you want.  Plus there is a limit you can expect to achieve.  I used Formica in a stainless steel finish for my poly units.  I would guess they are bowed about 8 inches out. 

You can do a hand sketch and use pi r squared and pi D formulas to calculate eventually the segment length of the curve you would need for x radius with the full center of the poly buried somewhere deep within the wall space and you calculate back.  I know how but obviously cannot explain it here.

I guess your bows were calculated to diffuse specific freqs.  I was planning some generic polys for the side and walls back walls in my HT.  I was going to fuse this concept with ethan winers design fir deep bass traps by using oc703 with air gap behind the poly and sealing it to the wall.  Any suggestions on a generic size to use?

[dBe]

Hi John,

What width do the plywood panels need to be if the strips are above referenced distance apart?

Nicholas

The standard 48" width is what we use.  The center to center distance determines the depth of the poly.  Don't get over zealous on decreasing the distance.  Popping an 8' tall piece of masonite into a spacing of 42" is not as easy as one would think.  Also, make sure the cleats are WELL anchored to the wall or they will become unguided missles in the room.

Dave

[dBe]

Here is a good place to go to get a really good grasp of room dynamicsIF you are so inclined:

http://www.acs.psu.edu/drussell/demos.html

Spend some time, think about what is happening in YOUR room and then let's talk.

Dave

[tasar]

DIPOLE TREATMENTS........"no pain, no gain"

Dave the URL suggested in your last post above was the best so far. Above is a Dipole wave depiction I lifted from site.

My room was purpose built with front/rear bay walls that serve to hide a sonic tube and poly fill, "closets" if you will. Stud walls are Roxul filled. I have no 90 degree intersects accept at ceiling. Dave convinced (beat) me to think of diffusion/absorption as "tuning" not "sound changing" tools......yes, there's a difference and a mindset that aids the empirical, which seems the method of room treatment "madness".

I've got the Super Vs, check out the waveform these dipoles throw. Anyhow, what works with the "box", not so here. I'm employing PIs new 4' diffusers, and where as Dave's room placement print above, is a guide, well, you'll see. Referencing other staged treatments doesn't help much without a different mindset. NO, treatments DON"T have to be on the floor or wall. Tried that here, but as shown I ended up quite different. I originally placed panels relatively in same locales but upon the floor and against the WALL.....WRONG. Though I could affect piano tones, strikes and the like by interchanging the male and female forms of the new diffusers, I got nowhere with image and stage. Voice and instruments were on the floor. Greg initially mentioned moving the center front diffusers out into the floor. Well hell, why not. On the floor they did nothing. Now, in comes Dave, "you have  to get things off the floor, like mid wall to ceiling". Whoa.....this is good. Piano and voice placement is now off the floor and where it belongs, but imagery not so hot. Moving the center panels off the front wall about 2' and raised just off the ceiling, while still 3' from rear of Vs, seem to max the stage height. Moving further off the wall produced no significant gains, so they're about 20" removed from the wall barrier, with no "mass loading" or backboards of any sort. Yeah, the props suck, but they do the job.

So, now the voicing is good but the side to side staging and imagery needs work. I placed 2 additional similar panels on the floor just ahead of those as shown in pic. WRONG, my "expert" pianist, spelled W I F E, said it "killed" the piano.....I agreed in every sense. They're gone. Dave's other advice was to go speaker outboard and skyward as with stage pictures taken at Axpona. AHhhhh.......yes, we're getting somewhere. Intuitively, I pushed them into the sidewall intersect, just off to the outside and behind the Vs, then played(listened) with them angularly till they are basically parallel with the speaker baffles. OH MY ! Try the piano, yes, the piano must be "right" in this household. It has to strike, decay, and resonate like the "big black box". So far so good. Now the female voice, yep, lifelike and on stage (perhaps realistically a little low) but all the instruments sound placement correct. Then, it's on to classical, good late model recordings. Big surprise ! For the first time, the symphony sounds like one, has side to side "fullness" with a field both wide and deep......VERY nice ! Can this get better ? Once the stage was "right", and only then, I could hear this whole sidewall resonance that started to irritate the other stuff I was hearing. I purposefully added no other absorption, so I could master the additive affects of treatment. Dave suggested using new diffusers on they're sides, to fill in at first reflection. Yep, the irritation was now mostly removed, gone. The ductboard, sized appropriately here, might do it.

My rear walls have similar shape with 2 of the new diffusers centered both on the wall and ears. They reside equal distance behind the listening area as the speakers do from the front wall. The empirical has not been applied at rear, but some minimal Roxul stands in the corners.

Bottom line, no absorption has been applied rear of speakers. Ceiling/corner intersects are next, along with correcting material at first reflection. I'd like to see the voice emanating a bit higher than instruments, but not sure this doesn't have more to do with recordings. Further, I wonder what ceiling first reflection might do to stage, depending on placement. My experience with rooms that have such treats, don't sound much different from where I am at the moment.

[SoCalWJS]

Looks very impressive - hope you manage to achieve your goals. Keep posting what you are hearing! I just received the AQD-1's about a week ago and am still experimenting on placement - nothing definite yet. I have found a couple of locations that were definite no-no's though It's nice seeing what somebody else is experiencing, even though I have LS-6'es which are quite different with regards to radiation patterns.

How have you attached the panels to the wall? I'm trying to figure out some sort of stand to place them on, but I don't want to rely strictly on gravity keeping them in place - I have cats which will eventually get curious enough to topple them over. I'm looking for something that allows the panels to be moved out of the way when need be, as I do not have a dedicated room.

[dBe]

DIPOLE TREATMENTS........"no pain, no gain"

Dave the URL suggested in your last post above was the best so far. Above is a Dipole wave depiction I lifted from site.

Yeah, it is a good one.  There are a bunch of useful tools that help to quantify and visualize what is really going on in real rooms acoutically.  We have to be able to do ray tracing and angles of incidence and reflection to get our rooms where they need to be.

Remember: you may have to re-aim the speakers as you move the treatments around to get the full benefit of the treatment.

Also: we can tune a room, but all we are really doing is getting the actualy sound that the system is reproducing to be fully realized and appreciated.m  We can't "fix" a system with room treatment.

Soldier on, mate  you are doing good.

Dave

[dBe]

Looks very impressive - hope you manage to achieve your goals. Keep posting what you are hearing! I just received the AQD-1's about a week ago and am still experimenting on placement - nothing definite yet. I have found a couple of locations that were definite no-no's though It's nice seeing what somebody else is experiencing, even though I have LS-6'es which are quite different with regards to radiation patterns.

How have you attached the panels to the wall? I'm trying to figure out some sort of stand to place them on, but I don't want to rely strictly on gravity keeping them in place - I have cats which will eventually get curious enough to topple them over. I'm looking for something that allows the panels to be moved out of the way when need be, as I do not have a dedicated room.

  The easy way to hang them is with picture hooks.  Glue a piece of 1/8" masonite or similar product on the back with a hole or holes in it to accept the picture hanger.

For more ideas on how to use them go to the link that I posted above - loads of info there on acoustics and application.

Heve fun.

Dave

[tasar]

OK, so on to absorption, a couple "hangup" questions

First, the "white faced builder's board"......I get blank stares at the box and specialty yards, most guessing you imply "homosote" type boards. Any specific ideas ?

Second, I mounted ROXUL at first reflection replacing Dave's new diffusion panels on their sides as shown. Less nasty resonance, and I was able to remove the diffusion rear and outboard of the Vs with NO detriment to the stage, so at the moment I consider these redundant and will next try absorption at the "ray" point of reflection on bow wall rear of Vs.

This I'll follow with FULL length(ceiling to floor) corner / ceiling intersect triangles. Not sure of sizing for these cuts, but the available DUCTBOARD is in 4 X 10 ' sheets, so maximizing seems logical for initial cuts. I know Dave has mentioned "builder board" here, but might as well use the lighter Ductboard with this sizing. Dave, any arguments for 1" or 1 1/2" Ductboard ? How about the full length corner triangle cutout, is the sizing dependant at triangle base(at top) and length ?

All suggestions welcome......."blow me down"

[dBe]

OK, so on to absorption, a couple "hangup" questions

First, the "white faced builder's board"......I get blank stares at the box and specialty yards, most guessing you imply "homosote" type boards. Any specific ideas ?

Second, I mounted ROXUL at first reflection replacing Dave's new diffusion panels on their sides as shown. Less nasty resonance, and I was able to remove the diffusion rear and outboard of the Vs with NO detriment to the stage, so at the moment I consider these redundant and will next try absorption at the "ray" point of reflection on bow wall rear of Vs.

This I'll follow with FULL length(ceiling to floor) corner / ceiling intersect triangles. Not sure of sizing for these cuts, but the available DUCTBOARD is in 4 X 10 ' sheets, so maximizing seems logical for initial cuts. I know Dave has mentioned "builder board" here, but might as well use the lighter Ductboard with this sizing. Dave, any arguments for 1" or 1 1/2" Ductboard ? How about the full length corner triangle cutout, is the sizing dependant at triangle base(at top) and length ?

All suggestions welcome......."blow me down"

Dave,

Here you go:  http://www.blueridgefiberboard.com/pages/wfbb/pdfs/wfbb-data-sheet.pdf Celotex has made this stuff for over 60 years.

First reflection points should be addressed with absorption.  Diffusion is for secondary reflections and specific locations like behind the listener and centered between the speakers in the front wall location.  You can adjust image size by moving the centerd front panel closer or farther from the listening position.

Ductboard?  Thicker is almost always better for first order reflections.  1-1/2" mounted an inch off of the wall will work down to the upper bass.  Great stuff.

You "may" find that the ductboard in the corners will suck out some of the image size and depth.  That is why I recommend the building board for these applications.  Plus the surface finish looks like an orangepeel and is easily painted to match the room.  Try it all and see (hear) what works for you.  I tend to like rooms a tad on the live side.  Deader rooms make me uneasy after an extended listening session.  Pshchoacoutics tell us that the ear/brain interface likes reflections.  There is no one size fits all when it comes to personal taste in differing rooms.

Rock on...   

Dave

[tasar]

When you consider an OB coax waveform being "sucked" forward as it emanates rearward (see previous post), it's not unlike the front firing wave. So,
for OB DIPOLES, "primary" reflections include side and ceiling barriers fore AND aft of the speakers. By my logic, you treat the front and rear as if mirrors of one another.

Dave, you've mentioned going overboard in size with first reflection sidewall absorption. When considering the Vs or other 12" coax, is there a point of diminishing return when it comes to panel size ? 2X2', 2X3', 3X4' ?

Further, when applying ceiling absorption, is there a critical angle at the leading edge ? Most I've seen have been mounted in succession, one behind the other, in lengths stretching from speaker to speaker, starting from reflection point back just over the listening position. I ask this as some have mentioned ceiling treats, done wrong, have killed the soundstage. Ductboard seems the logical choice here.

You also have implied one must be willingly to move the speakers. Maintaining the listening triangle to coexist with distance behind the speakers in relation to that behind the listening position, pretty much zeros things in. I have found excessively toeing in the Vs, is unnecessary. I'm at 1 1/2" toe and frankly don't hear a difference from when their baffles are in the same plane, or if they're looking straight at you. The "waveguide" does it's thing, any way you shoot them. With OB, it would seem excessive toeing would only exacerbate reflection issues. Besides, at 162 lbs, these puppies are a workout !

When addressing the ceiling corner intersects, it appears we're talking an isosceles shape. Question is what percent, of either equal side, should the base be ? I will cut full length, reaching floor, then make second pair half that size to try on front and back wall corners.

"White face" has been marketed as the perfect bulletin board material, according to sales. This stuff is special order in these parts.

[PDR]

I find this thread very interesting as I have the V-1s..(comparable to the supers) and have just finished....or so I thought...treating my room. I have absorption on the first reflection points, including ceiling, forward of the OBs, and bass traps on the rear corners. Diffusion is....so far....on the front wall between the OBs, a QRD with another absorption panel above it covering the corner of wall and ceiling. The QRD really brought depth and height to the soundstage.
I never thought of treating the first reflection point behind the OBs, but since they are only about seven ft from the front wall it never occurred to me. If I do try and treat these areas do you think it will affect the diffusion from the QRD?, as in being overdamped?
For what its worth I have the same findings as you regarding the toe in.
This is very interesting......thanks.

[dBe]

I did a quick and very dirty line drawing of ray tracing for reflections in rooms... don't laugh.  I used the computer equivalent of crayons to do this:



What you see are direct (first order) reflections in reds and lower order reflections in blue.  The ones to go after with absorption or the red guys.  These are the ones that will smear an image.  The reflection will be delayed about 1 millisecond per foot of flight time.  This is a BAD thing.  In the studio I often use a method of panning the instrument called delay panning.  Yep: delay.  It only takes a few milliseconds to move an image in the soundfield.  This makes the image, instrument or voice seem larger than life and a bit louder due to precedence effect.  Precedence effect says (basically) that arrivals between o-25ms are perceived as the same event.  Unfortunately, this screws mightily with localization in the soundfield (image).  The lower order reflections have lost a lot of energy and are what we hear as ambience.  These are the ones that will benefit the most from diffusion... this includes the area centered between the speakers.  This will not normally produce a direct reflection and needs to be diffused to maintain the energy in an uncorrelated form to eliminate the "hole in the middle" that absorption will produce.

Go get 'em.   

Dave

[tasar]

A picture paints a thousand words said Gates....hey his first name was Dave also
Aside from answers to the preceding post I see now why you suggested diffusion behind and outboard of OB. I followed this advice from Dave but haven't addressed first order absorption completely....when placing diffusion behind the Vs as
Pictured above, I may not have got them back far enough...so it appears the blue lines call for diffusion where I was thinking absorption behind the OB, though the corners could use some front side for
Different reasons.
As shown, where the crayon lines point to rear wall corners, some  is also called
For. So as with diffusion front and between speakers, my bet is these diffusion panels should be pushed higher toward ceiling....this makes sense as those woofers could care less at those wavelengthsl

[tasar]

Dave......those secondary reflections could really be drawn in many angles. correct ? When I trace a mirror off the wall behind the Vs, I see it striking right at the spot of first reflection ! So, this means I need absorption and diffusion at the same spot. I removed the Diffusion behind and outside the Vs, because even when stuffed lengthwise to and across the ceiling from mid wall, they produced no audible difference.

However, I moved the 2 pictured above between the speakers to with 24" of Vs rear. The voice image now has the proper height. Then I stuffed 4' length of Roxul mid wall up into the ceiling intersect at corners behind the diffusion panels. Wow, things are really good. despite the Jupiter upgrade, this really tones the Coaxs down in that stridency frequency zone. The instrument bodies, piano and acoustic guitar are more believable than ever. I do have the rear corners stuffed similarly with Roxul along with the diffusion panels centered. The room is as "quiet" as I would like, as with you, "live" is good. When using White face board at ceiling/corner intersects, you have mentioned 36" as large enough for the triangle's longest chord and that a cotton batt surfacing is of benefit. How "critical" is the sizing and surfacing if one were to poly fill the void behind such treatment ?

With all my treatments to the Vs going to the ceiling, perhaps a try at simply doing a ceiling intersect strip about a foot wide, with duct or a fiberboard type, would be far simpler........

PDR.....if you're looking in, yes, I see NO need to be pointing the Super Vs on any acute angles. The waveguide is an asset and the damn speakers look alot nicer standing as furniture and not glaring down at you like the barrel of a gun. Mine are toed 1 1/2", and could just as well be 3/4". I suppose there might be an "ideal" toe, but it would have alot more to do with subsequent wall treatment fore and aft, than with the sound quality to the listener.

Yo, Dave

[tasar]

It would appear ceiling drop panels are of the same fiberboard material. I've found these on the cheap in a 2x4' size at various material recyclers eg Habitat. These should fill the bill for those ceiling corner intersects

[tasar]

OK......anyone with Super Vs or OB Dipole......what and how do we best affect first reflection at ceiling ? Panels sized as with sidewalls or cut full distance above and between speakers ?

And Dave.....when I look at the secondary reflections, and because of speaker placement and toe, my second waves superimpose on the front corners and area of first reflection at sides. Do you do a dual treat. That is it would appear I need absorption and diffusion in relatively the same area.

[tasar]

Anyone here ? I took a serious look at what the boys at Real Trap do for LF trapping. They use a type of plastic "reflective" sheet behind and between the fabric cover and the 705 rigid glass. Rumor has it this reflective surface or membrane can be duplicated with Kraft or builders type paper......the pink stuff as used under flooring. I'm assembling frames and would like to emulate real Traps build. Also, most "ductboard has a foil and fabric like face so this "fabric may or may not be reflective or absorptive already. And what about layering a couple or three ductboard sheets to get a 3-4" thickness. does the foil backing defeat this process, and if not, I assume (oh boy) the foil always faces the panel rear......HELLO ?

[dBe]

Anyone here ? I took a serious look at what the boys at Real Trap do for LF trapping. They use a type of plastic "reflective" sheet behind and between the fabric cover and the 705 rigid glass. Rumor has it this reflective surface or membrane can be duplicated with Kraft or builders type paper......the pink stuff as used under flooring. I'm assembling frames and would like to emulate real Traps build. Also, most "ductboard has a foil and fabric like face so this "fabric may or may not be reflective or absorptive already. And what about layering a couple or three ductboard sheets to get a 3-4" thickness. does the foil backing defeat this process, and if not, I assume (oh boy) the foil always faces the panel rear......HELLO ?

Yes, David.  There is "someone here."  I have tried in every conceiveable way that I know to explain diaphragmatic absorbers to you on and off board for well over a year.   I have also encouraged you to buy the best/easiest DIY reference on general acoustics: The Master Handbook of Acoustics by F. Alton Everest http://www.amazon.com/gp/product/B002FVLAGA/ref=pd_lpo_k2_dp_sr_2?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0071360972&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1CX18T9XRC8SJC7E50TA for just about as long.  I'll say it again: without a basic understanding of fluid dynamics, ray tracing and reflectivity/absorption you are screwed.  Please, for the love of all that is acoustically transparent, buy the book.      Diaphragmatic absorbers have been around since the first thunder wavefront hit a leaf.  When you buy the book, you will find out why assumptions are VERY BAD THINGS in general.

Frankly, I'm happy to be anywhere, right now.  I had my followup, after hospitilization appointment with the pertinent doctors explaining what happened to me in the accident that I was in last week.  When the driverside airbag, didn't deploy, the seatbelt interia reel failed and the steering column didn't collapse several other things happened simultaneously.  I bruised my heart, bruised my liver, bruised a lung, broke the sternum, got a concussion, broke several processes in the spine and ended up feeling pretty friggin' grumpy.  I have a deceleration bruise on the roof of my mouth.     That's a new one on me.  I am bruised from the top of my shoulders down to the groin.  Looks like grainy eggplant.  So, at the expense of sounding like the gentleman from the Department of Redundancy Department, David, PLEASE buy the book.  That way when I croak you'll have a basic reference.

Dave

[tasar]

Thanks for making my point Dave...." Owners manuals" (books) don't tell all. Going back to the original thread, I'm "inbounds". Someone will certainly benefit. Remember when it comes to intelligence, it's not always what you say,
but what you don't. Wishing you "full" recovery !