Desert Sunset Theater Build - Page 6

I've felt some wiring get hot in the past, copper wiring, but I'm no electrician, just an observer and googler who probably knows just enough to be dangerous. You definitely sound more experienced than me so I'll go with what you say. I did the electrical in my theater and backyard (as well as 50+ cat6 runs and 72 security zone runs) and just from that I've learned conduit can come in very handy and it was worth every penny.

well i think the nice thing about andreas leading the way on the rotary build is that he does all the hard engineering work. the rest of us can just order parts from machine shops spec'd out based on his experiments and assemble.

Matt

well YOU have ME converting mine. I am thinking about cutting my towers down, putting 2 manifolds between my spare room and HT room, and my door will be just like your access panel. I plan on testing with the door sealed shut, sealed IB, and open, 11Hz tune with the 23" x 88" x 4" door way as the port.

I just downloaded all of your awesome pics to show my girlfriend for approval tomorrow. Having taken a closer look, your square access panel appears to be just right for an off the cuff test... once you get comfy and a good feel for your system, Id try it without the panel in place. Only issue though is with 2 of the subs right there, I think they'd cancel out and leak rather than load it as a port....if you could make 2 panels to block the 2 subs...eh... I dont think it would work, and I think you will be more than happy as is!

Again, great work and pics, should help me convince the GF though she knows full well my work wont turn out nice like that

The door is locked securely shut right now to keep SPL up in the single digits as it is, but i may convert the doorway into a giant port to test IB vs ported IB.

I know of one documented IB build, whereby the owner decided to vent the IB at a later date, with a tuned port. Hence the term, ported IB.

As you likely know, within the vented subwoofer type, there are several different variations.

LLT; large low tune
SLLT; super large low tune

An IB, utilizing an attic, crawlspace or similar area as the backspace is typical. However when one designs a tuned port to augment the response (at the expense of all response below tune), a name of ported IB seems appropriate, regardless of technical accuracy in my opinion. When you see it, it's a ported IB. All that said, you're right, it is ported and SLLT is most likely the correct designation.

LLT description. This is an outstanding explanation by guru Steve Callas.

LLT vs. SLLT explanation

The individual that transformed his IB into a SLLT, wanted more impact, feel etc. Oftentimes the IB alignment, is so transparent and clean, that the dramatic reduction in distortion, isn't overwhelming in the short term. The high resolution, transparent nature is more more pleasing over time. Without a peaky response, either inherent or EQ'd in, an IB allows the material throughput to be rendered cleanly, and without un-natural emphasis. This critically damped, low Q response isn't of the "blow you away" variety. However, it doesn't wear thin over time either. Subwoofer subjective terms such as "slam", "impact" etc., are merely descriptors of frequency response characteristics. If the ported IB gave the owner what he desired, that's great. However, below tune, with any vented design, response drops off in a big way, and distortions rise dramatically.

Many contemporary motion picture releases recognize the realism of including infra-sound content down into the low single digits, and this energy helps create a very realistic suspension of disbelief. So if system response down to the 3hz (to cover the LFE specification of 3-120hz), is the desired outcome, even the best vented design can not get you there.

Back OT; I'm looking forward to you integrating and optimizing your IB, and of course your impressions of the IB system.

Good luck

That first pic, looking forward toward the screenwall,...wonderful. Just a kick ass blank slate from which to continue. I would suggest that you fire up the IB, and check the modal behavior of the room. If you have any main LP placement flexibility, now would be an ideal time to determine where any front to back nulls will reside. It's very likely that you'll have nulls of perhaps 20db or more, at certain distances from the front wall.

Additionally, a side benefit would be determining any subtle buzzes or structure borne vibrations from the IB. Also, I've no idea as to your acoustical savvy, however are you familiar with the 38% rule? Reading this isn't necessary, but looking at the visuals helps a bit. Wes Lachot, studio designer, often writes articles regarding room design, and optimizing acoustic relationships within a space. Also, and much more importantly, is an essential work from Toole is "Getting the Bass Right". It really is a superb piece IMO. I believe I already posted this link before, however in case....

Nice job so far. I know very little wrt HVAC, but it's nice to see progress.


Good luck.

My concern would be independent of the impact of any of the items you mentioned. Also, typical super-chunk bass traps aren't ideally suited to address LF anomalies in the octaves I'm referring to (~35-80). Most any room with LF sources along the front wall will have a potential null at some point front-to-back. If you've got flexibility with placement of the primary LP after the fact, this is of no concern now.

The few ways to address these type nulls include distributed sourcing, a Double Bass Array, limp mass membrane or equivalent, ...or flexibility in seating proximity.

Just a thought, nice progress

You could help me here. Viewing distances specifically, and the video side of things in general is certainly not my area of interest. However, isn't the 234 formula, whereby;

Optimal viewing distances, x = screen height

2x Closest
3x Optimum
4x Maximum

Are these correct, an the guidelines you're using?


Thanks

I thought it was based on ability to resolve individual pixels, but I'm not sure. With greater rez, one can sit closer for greater immersion. I always thought that's what it was based on. There's an ideal distance for any rez, closer and one can delineate pixels, any farther and the additional rez is rendered useless. That said, I'm way out of my wheelhouse,...I was hoping you could school me on this

I know there's a chart on this 234 (my name) rule of thumb. It shows all the different standards, like SMPTE, THX, DOLBY, etc, and illustrates the minimum distances, and most distant seating suggested. If Dennis is on it, I'm sure you're fine. If I stumble across that chart, I'll post it up.

Thanks

Cool. Any close up of the clips or a link?

Nice detail on the clips.