Yes Dear, I'm down here working on your craft room!! - Page 23

Arc-1: "Arky Smarky"

Haven't left the room in two days, and my jaw hurts from grinnin!

I lack the vocabulary to describe what Adam accomplished with the parametric eq so we'll stick with "magic".

The best way I can attempt to describe the results, is that I've gone from watching concerts/movies to being in the middle of them, regardless of the venue, the room is now able to recreate the ambiance of environments ranging from a small jazz clubs to large halls, with such realism that your easily transported to a different place and time. Watching "Adele Live at the Royal Albert Hall" is nothing short of "goose bumpy" now that I have front row seats "in" the hall.

We did end up moving the seating position back ~ 12" for improved response. After installation of the additional Triad in wall subs, Adam dialed them in with the IB and the tactile response of the room became indescribable. Jumping / Ducking have become normal activities during movies now. The experience is truly difficult to put into words, and a first for me.

The opportunity to watch Adam work did as much for my personal education as it did for the room. After a couple of years of digesting acoustical principals/theories from text and the forum, it was an enlightening experience to watch a true professional bridge the gap to practical application. Not to mention he accomplished this with a 6 foot, 180 pound monkey tethered to his backside for two days.

Overall I was exceptionally pleased with the room's performance. From memory, we found one rattle at ~ 39 hz in the arch, easily corrected with one screw, and another in one of sconces that I believe was around 48 hz. Some work to do on the hush box still, but other than that I believe an NC24 may have been the highest reading, and thats without the door seals. Honestly there were so many numbers flying around I need to wait on Adams official report for the technical details.

Originally I thought I was saving a couple of months by having Adam visit rather than running through the process myself. But now I feel that even if I had possessed the 50K or so worth of equipment he lugs around, I may never have achieved the same results, and I now view the entire process as "Art" mixed with supporting technology.

"How good is good?" ... Bottom line is, without having committed to this process I would never have known what I was missing, since I lacked a baseline for comparison.

Oh.. and i guess a good accoustical design never hurts either

Cant say as I have noticed any Sag, but then again cant honestly say I've put much time in looking for it either... based on my limited understanding i dont believe that sag is as large a concern now with improvements in cone/suspension materials as it was several years ago..

an interesting comment about the IB and Adams recent visit... after the initial readings were taken, Adam modeled the room and the actuals were not lining up very well with the model. after some head scratching it was determined that below certain frequencies the front was was not the front wall, the front wall was actually the rear wall of the IB chamber... in retrospect this makes perfect sense considering the two big holes cut in the front.

After several hours of pink noise.. Im not sure I heard everything he said...
He was very familiar with IB's, and didnt seem to have any issues at all phasing in the rears with them. I like most others chose probably the worst starting position for the IB/manifolds.. dead center on the front wall. (rather than at a quarter point as example) this placement also prevents us from building a baffle wall to reduce/eliminate SBIR.

We didn't discuss specific performance differences between these and sealed subs.. but 1/2 way through the second day his smile was nearly as big as mine, He truly enjoys his work.
I'm trying not to sound repetitive but the tactile feeling in the room is phenominal, and the LFs seem so so clean and effortless... unlike anything I've ever heard. The only specific comment I can remember is him saying "You can really pressurize this room"

The BFD was retired and everything ran through the QSC DSP, any reservations I myself may have had regarding the IB after my feeble attempts to eq were completely put to rest by the time he was finished. I wouldn't hesitate to do it the same way again.

Sorry Guys, I've been neglecting my thread
I'll get more pics of the rest of the room posted soon, back included

RT.. Wow! thanks for the kind words. I sincerely enjoyed your visit and our conversations, it was refreshing to show the theater to someone who appreciates all the various aspects of what goes into a room.

Jeff C.. Ah.. proof of life.. been waiting on your star ceiling update. Curious about your impressions of the light engine you chose. I've been contemplating a small star ceiling that I can implement with out having to run fibers back to a large illuminator.


JPA.. Please dont base any of your design desicions on my incoherant ramblings.. my earlier post was more of an overall refrence to having only a single sub on the front wall (like most) and the need to add the triads to smooth the response. Additionally at that time I was thinking that my manifold height was causing a frequency notch at my previous seating position because it was equidistant to both the ceiling and the side walls.

Regardless of the placement of the IB (or any sub), I think the important thing to take away from the Welti paper Moggie posted is that Multible subs, with locations other than just the front wall, will be required to reduce the total variation across the seating area.

Using the Harmon paper to illustrate my overly simplistic, less technical, understanding of the "multiple subs" concept:

Configurations 1-5, 8 & 9 in investigation 4 from the paper where all subs are located on the front wall only, the results are similar for the MIN-Max variation regardless of the number of subs used. Although we can increase the number of subs or increase the SPL (think IB) at these locations, it wont necessairly (and most likely will not) improve the overall response across all seating positions becasue we are just adding more energy to any existing modal issues, additionally we end up needing to add more treatments to suck this excess energy back out of the room.

Another important behavior from the various placements can be observed in configurations 21 and 23 from investigation 6. (disregard SBIR issues with this placement for now) Note that although only a single sub is used, they have been moved away from the boundries more towards the center of the room and this configuration exhibits less min-max variation than configurations 22,24,25 where the subs are located "on" the front wall.

When the sub is moved away from boundries towards the center of the room the less energy we are feeding the room modes, so we get less variation in the SPL across a larger area, Although it's not practical in most situations to have a sub in the middle of your seating area, this general concept becomes important when considering the behavior of multible subs.

When two subs are located, say in opposing locations, such as in configuration 6, the resulting interaction of the 2 subs is very similar to the result you would get by placing a single sub in the center of the room.

These opposing subs create a single "imaginary sub" at a point between them, and through interfearence and reinforcement we in essence have moved thier combined output to the center of the room, thus realizing a similar reduction in the SPL variation that is seen with a sub actually placed away from the boundries.

And lastly as Adam pointed this consistancy does not necessairly translate into good but once the variation has been minimized, then parametric Eq can be used to flatten the response.

Also note that although the harmon paper emphasizes an even number subs at symetric locations there are other approaches that can be used to create this imaginary sub and a consistant response at your seating locations that may offer more flexibility in meeting specific needs/constraints of a room


I've not had any alcohal yet today, so hopefully this was somewhat coherant, I realize this is an extremely overly simplistic view of a complex subject, but this is how I got the need for "multiple subs" to fit into my box. Maybe others can correct any my misconceptions.


Thanks Moggie.. Heres another refrence from cedia that has some cool depictions of the spatial deviation from various sub configurations.

http://www.cediacrosspoint.com/conte...r-optimization

This one was eaiser for me to try to grasp ... because of the pictures

Good to hear from ya RT, hope all is well with the family.

Im still around.. Just not "These Parts" anymore. Been a busy year.. relocated to AZ during the summer. Broke my heart to leave the theater behind..

The new house had a so called "Theater room" but its not much bigger than a large storage closet and thats exactly what its being used for "Storage".
I just submitted plans to the city so I could start construction on a 26 x 40 building.
I'll dedicate ~ 16 feet to a new theater, and the rest will be a workshop, bar, general hang out area..

I'll start posting pics again once the ground breaking begins.

Great to hear from everyone....

It was like leaving a kidney behind. The oldest one stayed with me the last couple of days before leaving for AZ, and it was ~ 20-30 min after we pulled out of the driveway for the last time before we said anything.. both of us (I know me for sure) were afraid if we talked we would start crying.

The theater ended up being a double edge sword during the sale. It was definatly a hook to get people interested in the house, but it ended up being a point the buyer leveraged for negotiation.
I had removed all the equiptment (except the IB and projector) and replaced everything with an older 5.1 processor and a set of NHT's I had. (knowing I could never get the value out of the equiptment, and I was already up aganist it for being at the TOP end of the range for home prices in the area).
But i can honestly say the room still sounded great, not near what it was with the DSP and everything calibrated, but still "great".

The buyer called in his "AV EXPERT", and after his expert was done with his evaluation he stated it would take 10-15K to bring the room up to speed.... New speakers.. new amps.. updated processor.. updated projector..bla bla bla... there was absolutely no appreciation or understanding of Room in Room construction , double drywall, green glue, perfsorber etc etc etc... This situation was probably compounded by the fact I had already moved and everything was left up to the realtor.

So when they stated this to my realtor , you can imagine how it sent me up a wall. Neverless they ended up purchasing the home.

In the end I dont think the Theater room added one red cent to the sales price.. again this could have been primarily due to the the region and lack of potential buyers in that price range. Honestly Im just glad the house sold before winter.....

One other side note.. if you have a basement and live in the northeast/midwest check for radon before listing your house... the thought had never crossed my mind but ended up being a thorn for remediation.

Ill start breaking gound on the home for the new theater in the next month or so.. hopefully with the same lighting fast results as before:cool:

Brad