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Why not? He has vertical modal issues, and also flutter echo issues. Hard backed and hung at an angle wont solve those entirely, obviously, but it sure will help. Is there a reason why you think it would be a bad idea to make it hard backed in this case?Dont make it hard backed.
That's pretty big! You'll need some heavy duty hardware to hang that safely. Think: eye-bolts, chains, ...The cloud will be 6' x 6', 4" deep. It will hang at a 12º angle over the mix position.
It will be 2 separate 6 x 3 panels. Not sure how I'll connect them together yet but yes I was thinking eye bolts and chains. My contractor said he will come by on Sat and help me hang them. I need to find a way to anchor them to the ceiling without undermining the isolation. Not sure about that yet but plan to scour the forums and see what turns up.Soundman2020 wrote:That's pretty big! You'll need some heavy duty hardware to hang that safely. Think: eye-bolts, chains, ...The cloud will be 6' x 6', 4" deep. It will hang at a 12º angle over the mix position.
- Stuart -
Exactly right! That's what I'm suggesting: Thick plywood or MDF (perhaps 18mm or so) properly hung on chains, like Brian did (based on Glenn's design). It won't completely change the mode, of course, but it certainly will have some effect. A quarter wavelength at 63 Hz is about 4 1/2 feet, so a hard backed cloud 6 feet on each side is certainly big enough to be noticed by the standing wave. Without the backing, there wont be much effect at all on the mode.It would have to be pretty thick backing and solidly mounted to change the modal issues at 63hz,
True, but 4" of absorption isn't very effective down at 60 Hz, even if spaced off the ceiling. For maximum efficiency, it would have to be spaced 53 inches off the ceiling... (theoretically). So spacing it 4" away, or even 6" away, or even 16" away from the ceiling (which is what OC shows in there specs), is not much different than no spacing at all for such low frequencies. It's only a small fraction of what the distance you'd need to have any real benefit.When 703 is measured off the wall the absorption levels are higher,
Sure! But you can also put absorption on TOP of the hard back, for even more effect! We did that once a few years back in a church here in Chile, and it worked out great. It can't be seen from below anyway, so you don't even need to make it look pretty with cloth over it. We just cut it a bit smaller than the size of the panel, so the edges aren't directly visible from below, and it looks fine.I just look at the open back as more opportunity for absorption,
It would be interesting to see tests for backed and unbacked! But I'm betting that there will be a significant effect, like there was in Brian's case. I understand that Glenn does this a lot, and has also had excellent results with it.I didn't think it would be a bad thing to be backed, just unnecessary.
Thanks so much RJ! Yes it helps enormously! I was wondering how i was going to mount the cloud. I have access to the space behind my ceiling so I'll climb up there first and do precise measurements of the ceiling joists. I then plan to get some large eye hooks and screw them through the 2 layers of 5/8 and into the joists. Then chain and S hooks for the cloud. I'm going to pick up the cloud in a few hours so I'll have a better idea of what it weighs before I shoot down to Home Despot and pick up the hardware.RJHollins wrote:Just a suggestion ...
The 3 hardbacked clouds for my build can be seen here
http://www.johnlsayers.com/phpBB2/viewt ... &start=390
Go about halfway down the page for details & pics.
The clouds are very secure
Under Glenn's guidance, I can also confirm that the floor to ceiling issue is handled with
hardback clouds at an angle. I still have adjustments to make to fine tune & maximize the
treatment.
hope this helps.
Thanks for all this input guys!Soundman2020 wrote:Exactly right! That's what I'm suggesting: Thick plywood or MDF (perhaps 18mm or so) properly hung on chains, like Brian did (based on Glenn's design). It won't completely change the mode, of course, but it certainly will have some effect. A quarter wavelength at 63 Hz is about 4 1/2 feet, so a hard backed cloud 6 feet on each side is certainly big enough to be noticed by the standing wave. Without the backing, there wont be much effect at all on the mode.It would have to be pretty thick backing and solidly mounted to change the modal issues at 63hz,
True, but 4" of absorption isn't very effective down at 60 Hz, even if spaced off the ceiling. For maximum efficiency, it would have to be spaced 53 inches off the ceiling... (theoretically). So spacing it 4" away, or even 6" away, or even 16" away from the ceiling (which is what OC shows in there specs), is not much different than no spacing at all for such low frequencies. It's only a small fraction of what the distance you'd need to have any real benefit.When 703 is measured off the wall the absorption levels are higher,
The angling helps there too (slightly). Angling the cloud at 30°, for example, increases the path length by 50%, so the 4" is effectively 6". Even with only a 15° tilt you are still getting better than 25% increase in path length, so 5" acts like 6".
Sure! But you can also put absorption on TOP of the hard back, for even more effect! We did that once a few years back in a church here in Chile, and it worked out great. It can't be seen from below anyway, so you don't even need to make it look pretty with cloth over it. We just cut it a bit smaller than the size of the panel, so the edges aren't directly visible from below, and it looks fine.I just look at the open back as more opportunity for absorption,
It would be interesting to see tests for backed and unbacked! But I'm betting that there will be a significant effect, like there was in Brian's case. I understand that Glenn does this a lot, and has also had excellent results with it.I didn't think it would be a bad thing to be backed, just unnecessary.
Of course, like you say, the backing does have to be substantial: thick, rigid, and massive. And it also has to be well mounted to the ceiling.
- Stuart -
Yes I would agree Eric. That's my "last resort" plan as I have mentioned before that my construction skills are less than zero. I'll do it if it's the only way to deal with the modal problem. I can't see myself spending so much on my room and my monitors and then flaking on the last thing to make the room sound right!Eric Best wrote:Makes sense.
I would think of taking care of the modal problem with tuned helmholtz or panel absorber, but there are so many ways to deal with these things.
Cool! So maybe we CAN do those tests, and settle the issue (to a certain extent). take careful REW measurements just before you put the cloud up, then again when it is up, then take it down, put the backing on, put it back up again, and take the final measurement.I wasn't sure what to do so I ordered the cloud without backing. I can always add the backing later
Shouldn't be a problem: each 6' x 3' panel of 3/4" plywood will weight about 40 pounds (3/4" is roughly 2.2 lbs/ft2). Let's be generous and add another 40 pounds for the frame, rock wool and mounting hardware (VERY generous), that means each cloud will weigh about 80 pounds. Spread that across 6 chains / eye bolts (three down each side of the panel), and each chain / eye bolt is holding only about 13 pounds. So it shouldn't be a problem, assuming that your joists can handle an extra 160 pounds total load. Once again, that will be spread across 3 joists, so each joist only needs to handle an extra 55 pounds, roughly.if I make sure that the ceiling anchors can take the extra weight.
Yes! Did my plan of taking 5 or 6 measurements around the mix position and then averaging seem like the right thing to do?Soundman2020 wrote:Cool! So maybe we CAN do those tests, and settle the issue (to a certain extent). take careful REW measurements just before you put the cloud up, then again when it is up, then take it down, put the backing on, put it back up again, and take the final measurement.
OK so here is where I am at with that. My ceiling joists appear to be 2 x 7.3" after measuring them. I was at the hardware store and the guy said I should try and go THROUGH the entire joist with an eye bolt and then use a washer and nut on the back followed by some thread glue. This is the bolt he suggested. It's 1/2"x12". My idea was to use something like this.... so it screws into the joist quite a ways. I think with 3 down each side of the panel it should be good. Am I wrong?Shouldn't be a problem: each 6' x 3' panel of 3/4" plywood will weight about 40 pounds (3/4" is roughly 2.2 lbs/ft2). Let's be generous and add another 40 pounds for the frame, rock wool and mounting hardware (VERY generous), that means each cloud will weigh about 80 pounds. Spread that across 6 chains / eye bolts (three down each side of the panel), and each chain / eye bolt is holding only about 13 pounds. So it shouldn't be a problem, assuming that your joists can handle an extra 160 pounds total load. Once again, that will be spread across 3 joists, so each joist only needs to handle an extra 55 pounds, roughly.
Ha!Eric Best wrote:I would think that those are overkill.