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post #1141 of 1179 Old 07-17-2014, 09:10 AM
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Originally Posted by hopefulfred View Post
you've got books, right? Get on it!

moar reading!!!!

:d
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post #1142 of 1179 Old 07-17-2014, 09:11 AM
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MOAR READING!!!! :d
HAHA!

Dude, are you made of leprechauns? Cause that was awesome!

The Plains Theater Has Begun
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post #1143 of 1179 Old 07-17-2014, 09:25 AM - Thread Starter
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Yes.
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post #1144 of 1179 Old 07-17-2014, 10:31 AM
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Fred, WRT the earlier post regarding the resonance and what being measured below ~ 60hz.
I was looking for the fly in the ointment regarding the measurement setup and the differential between the predictions and the actual results.. particullarly your readings for the first 2 length modes, which should be fairly predicatble regardless of changes in width/ height, soffit to soffit, floor to soffit, soffit to riser etc...
I cant see the short face of the riser or even the entry impacting these modes to the extent that it would shift the 1st or second length mode signifigantly from the predictions. These should be the most predicable and eaisest to correlate with even seemingly substantial changes.... Ie if your room measured shorter by 10% or longer by 10% to account for the face of the riser/ entrance etc.. the 1st and 2nd modes would still be 29/58 and 24/48 respectfully... Heres a quick graphic overlaying the predictions with a +/- 10% band compared to actual measurements:



Basically I was throwing darts at the 35Hz peak.. which I couldnt account for with what I thought were reasonable assumptions on the 1 or 2nd length or 1st width modes...... it just seems "out there" so to speak...
now that I read it,, this may not make sense to anyone else.....hmmm

as Albert said 'In theory, theory and practice are the same. In practice, they are not.'

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post #1145 of 1179 Old 07-17-2014, 10:59 AM - Thread Starter
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I'm going to keep looking, and I appreciate all ideas. Thanks, and don't hold back.

Where did you get that image?
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post #1146 of 1179 Old 07-17-2014, 03:07 PM
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Here's a surprise. I placed my order with HVACQuick on the afternoon of July 6. The grills arrived at work yesterday. That's super-quick, especially given that the website and order confirmation email say standard production is 3-4 weeks.

The blue is the protective film, the grills are brown, as expected.

I also ordered some right around the same time and was shocked at fast they came in. I paid the $4 each or whatever for the two week as opposed to the 4 week lead time, but I'm not convinced that there's really any difference.
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post #1147 of 1179 Old 07-17-2014, 06:47 PM - Thread Starter
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Remember how I started taking measurements saying that it was confounding? yeah...

Here's the frequency response plots for the three measurements I kept the first time, as a reminder:


And the list of predicted modes:


I went back downstairs today to pour out two more bags of sand (looks like one more will be the last one) and consider some of the things that came up in the discussion of the first set of measurements. In the process, I measured the diagonal that J_P_A mentioned in reference to the mid-30s peaks - it is about 14 feet as predicted. When I did that, I may have nudged the mic an inch or two, but I can't believe that the small movement of the mic will have changed the measurements to look like the new ones. I figured I would start with duplicating yesterday's work, just to verify set up. Well, the levels got adjusted again, so not only are these levels not absolutely right, they can't be compared directly to the first set (in terms of level).


Here's the two sets of measurements on the same plot:


I don't know what to say about that.


Next I moved the mic to the center of the rear plane of the room. The mic was hanging from the outlet where the HDMI runs through the face of the rear soffit to where the projector will go. The mic hangs down to approximately the center of the vertical height. I didn't measure when I set it up - only just now as I write this up. It's 52 inches from the riser deck, and 40 inches from the ceiling. So it's 6" above the center of the rear air space, and maybe two or three inches to the side. Without adjusting anything in the computer or soundcard - only moving and replacing the drywall "door" I generated these three sweeps.


At this point I also generated a waterfall graph for this new set:


That's when I noticed the hum in the noise floor at 120Hz. I assumed it was because I had the laptop plugged into the wall. So I unplugged it and tried again with some sweeps. This is when the impulse error I had yesterday came back. I tried three sweeps, all with the same error. I then plugged the laptop back in, and the error went away. Magic. I also noticed that the level changed when the power cord was unplugged. There's something going on here. I don't want to get into it right now if there's anything useful to say about these new measurements; but really there may not be anything worth saying, because I am now less confident in all of these based on the weird influences of the power cord that I've noticed.

Last edited by HopefulFred; 07-17-2014 at 06:59 PM.
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post #1148 of 1179 Old 07-17-2014, 08:25 PM
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I feel your pain, sir! After all the measuring I did to try to figure out my fan issue, I finally decided none of the plots were correct. There's a lot to get your hands around with REW to feel like you can get repeatable measurements.

Dude, are you made of leprechauns? Cause that was awesome!

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post #1149 of 1179 Old 07-19-2014, 06:27 PM - Thread Starter
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Yesterday after work, my only friend with a truck was good enough to meet me at Lowe's to bring home a few more sheets of subfloor. I got one last bag of sand, which officially overfills the stage. I'm trying to stuff the sand in there so that any settling won't leave any open area (overkill, I imagine). I think I'll have to pull out a little as the last of the decking goes on. I go one 8' length of the stage covered with one layer of decking tonight, caulking along the edge. Now that I'm out of caulk, I'll wait until tomorrow to seal it up.

Meanwhile, I want to cut out the soffit face for the new grills. I held one up in a place that seemed right to me and traced around it, but chickened out before I cut it out. The face of the soffit is about 10-11", but the opening will be limited to the center portion, due to the ripped 2x4s framing it (does that make sense when I say that? do you see this?) So the hole could never be closer to the ceiling than 1.5", and could never be within 1.5 inches of the bottom (not counting the sheething on the bottom. That is the say, there's a 7" gap into which the hole can be cut. I haven't even really thought crown molding or anything up there, so I have no idea how low or high is appropriate. Should I just make it as low as possible?


Hopefully you can see the pencil mark on the drywall.

I need MOAR CUTTING!
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post #1150 of 1179 Old 07-20-2014, 09:17 AM
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I'd be really curious to see how your measurements compared to this calculator: http://www.bobgolds.com/Mode/RoomModes.htm

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #1151 of 1179 Old 07-20-2014, 06:39 PM - Thread Starter
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Mike, I think all the calculators use the same math. They all make the same predictions, given the same inputs. If they were sophisticated enough to do more, they would need a lot more input data. The differences come out in the presentation of the data. Bobgolds gives a lot of data, I just get swamped by most of it.

The stage has a top. (Pardon the mess) It will get another layer of decking in a few days.



The HVAC grill has a hole. And it fits pretty well - you'll just have to trust me on that part.



Baby steps...
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post #1152 of 1179 Old 07-22-2014, 10:40 AM
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Looking good Fred!

I meant about the data was how your measured results would compare to the predictions and calculations. reality vs theory. My understanding is things are not always as they might seem.

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post #1153 of 1179 Old 07-26-2014, 06:34 AM - Thread Starter
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Always on the lookout for things I might need, I ended up with four used ball-bearing door hinges yesterday. A customer in a truck was trying to get rid of a couple old doors - large heavy solid wood doors from an old school. I would have taken a whole door, but they had louvered vents in them. He had already tried to leave them at some shops, but nobody was interested - so he let me have the hinges. Other than heavy looking and ball bearing, I didn't know anything about them before I got them off for inspection.

They're Stanley 179 Ball-Bearing hinges. http://Www.stanleyhardware.com/detai...inges-s060-003

Stanley says "for medium weight doors of average frequency." Anybody have any idea how much door four of these will support?
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post #1154 of 1179 Old 07-26-2014, 07:15 AM
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You are probably safe to about 375 pounds, four screws and that ply metals should hold up to that. I'm probably betting it's actually rated officially at like half that but just looking at the metal ply and knowing what each screw can hold, multiplying it time four screws... It's obviously good for a few hundred pounds assuming you catch good grip with the screws into both the door and the case.

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #1155 of 1179 Old 07-26-2014, 07:25 AM
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Quote:
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Always on the lookout for things I might need, I ended up with four used ball-bearing door hinges yesterday. A customer in a truck was trying to get rid of a couple old doors - large heavy solid wood doors from an old school. I would have taken a whole door, but they had louvered vents in them. He had already tried to leave them at some shops, but nobody was interested - so he let me have the hinges. Other than heavy looking and ball bearing, I didn't know anything about them before I got them off for inspection.

They're Stanley 179 Ball-Bearing hinges. http://Www.stanleyhardware.com/detai...inges-s060-003

Stanley says "for medium weight doors of average frequency." Anybody have any idea how much door four of these will support?
Fred, I believe those are the same hinges on my door.....I have three, not four. My door weights 230+ lbs if I recall......
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post #1156 of 1179 Old 07-26-2014, 07:40 AM - Thread Starter
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That sounds like good news! Thanks.

And I kept the screws too, which were also beefy.
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post #1157 of 1179 Old 07-26-2014, 07:41 AM
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post #1158 of 1179 Old 07-26-2014, 08:02 AM - Thread Starter
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Tim, assuming Trimark's ranges are the same as Stanley's, should I be able to extend the door weight by a third when adding a fourth hinge? I presume that three is standard and hinges are rated assuming that installation. 100lbs might still be all I use, but a little flexibility to add mass would be nice.
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post #1159 of 1179 Old 07-26-2014, 08:23 AM
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Yes, you should have no problems with the extra weight with just the 3 mortised hinges. They hold a surprising amount. For peace of mind, you could increase the number of hinges to four, but you really don't have to think about it too much unless your door is really (i.e. Dennis Erskine) heavy....and then the framing behind the wall is your biggest concern, making sure you have sufficient blocking and tying multiple studs together to distribute the hinged side of the load over a greater portion of the wall and not just the studding on the other side of the door jamb.

I'd also give Stanley a call to see what their customer service can tell you about maximum door weights for that 179 hinge, FWIW.
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post #1160 of 1179 Old 07-29-2014, 05:20 AM
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OK....curiosity got the best of me so I called Stanley Hinge customer service @ 800-337-4393 and spoke with someone in their technical team. For the 179 hinge, they recommended a maximum door weight of 175 pounds for either a 32" or 36" width door. Interestingly, adding a fourth hinge did not affect the weight rating whatsoever.

If you exceed 175 pounds, they recommended that you go to a 'heavy duty' ball bearing hinge like the #168 .

I hope this information helps!
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post #1161 of 1179 Old 07-29-2014, 05:44 AM
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I used those hinges to hang a door on an outside bathroom I did and my homemade door was like 40" and over 200 pounds. I hung it in 2012 and no issues. FYI. I'm not exactly sure it's the same hinge, I probably used the cheaper one without ball bearings actually. Moral of the story is it swings open and closed

I knew doing it that it was probably heavier than rated for. I wouldn't be too concerned. Just hang your door. MOAR DOOR HANGING!

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post #1162 of 1179 Old 07-29-2014, 05:48 AM
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Yep. I agree that there is a bunch of over capacity built into the hinge strength. As an addendum to my comment above, they said all of the load is really concentrated on the top hinge, making it the most important for the strength rating being how it is. I didn't ask if extra blocking, using all 3" wood screws, etc. affected the rated load....but I am sure it would.
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post #1163 of 1179 Old 07-29-2014, 06:32 AM - Thread Starter
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Your curiosity is working out well for me. Maybe you're curious what my theater will look like if you were to come build it for me.

Thanks!
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post #1164 of 1179 Old 07-29-2014, 09:35 AM
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Your curiosity is working out well for me. Maybe you're curious what my theater will look like if you were to come build it for me.
nice try!

Under construction: the Larch theater
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post #1165 of 1179 Old 08-19-2014, 07:47 AM
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Any updates? I'm sure you've been working in your theater so much that you just haven't had time to post pictures right? Already watching movies, by chance?
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Dude, are you made of leprechauns? Cause that was awesome!

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post #1166 of 1179 Old 08-19-2014, 07:51 AM
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That was well timed J_P_A. Fred needs to demonstrate some progress me thinks.

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #1167 of 1179 Old 08-19-2014, 07:53 AM
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That was well timed J_P_A. Fred needs to demonstrate some progress me thinks.
Yeah. No pressure, though. I'm sure it'll take me an hour or so to find my torch and pitchfork

Dude, are you made of leprechauns? Cause that was awesome!

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post #1168 of 1179 Old 08-19-2014, 10:54 AM - Thread Starter
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Unfortunately, not much happening around here. I've had out-of-town guests for about two weeks now. It'll be at least another week before I have any time.

Thanks for checking in, though. I need the prodding from time to time.
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post #1169 of 1179 Old 08-19-2014, 11:10 AM
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Lettuce face reality ... You need it all the time
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post #1170 of 1179 Old 08-19-2014, 11:12 AM
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Lettuce face reality ... You need it all the time
Wait, did you just call Fred, "Lettuce face"?

Dude, are you made of leprechauns? Cause that was awesome!

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