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PostPosted: Sat Jun 09, 2018 9:08 am 
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The hangers are much lighter in weight and somewhat more "springy". I think I get it now, why it should work much better.
:thu:

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Looks like these 4 disc pads should do the trick
You will be placing pads ABOVE the speaker? Between the top surface of the speaker and the upper panel of the enclosure box? They will be exerting some pressure downwards on the speaker, so you need to account for that in your calculations. Add it to the weight of the speaker itself, since it basically acts like extra weight, and causes extra deflection.

This is why it's important to build the box outside of the soffit, with some calculation and some "trial and error", to make sure that you get the correct deflection on ALL of the pads, on ALL sides of the speaker. The speaker itself won't be perfectly balanced: probably a bit heavier on the left side, or the right side, or heavier towards the front, or the back. You need to distribute the pads under it accordingly, so they are all deflected the same amount. If one pad is deflected significantly less or more than the others, that messes up the resonance calculations.

Floating speakers correctly isn't easy, but it sure is worth the trouble!

- Stuart -

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PostPosted: Wed Jun 13, 2018 1:41 am 
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I spent 2 days deconstructing everything and then trying to get the speakers mounted corectly on sorbothane pads. I'm still not 100% sure I got it right but at least this time I knew what to do. Hopefully the measurements will tell something.

Here's the measurement of the empty room: Baseline empty room

Here's the measurement of the empty room with the new version of the hangers installed: Hangers only

I'm not sure what should I look for in the graphs - the extremes seem to get even more pronounced, but is it good or bad thing? Is it because they cleared up some of the other problems? Do the hangers work at all? :?

There's still significant difference between left and right speakers. Could the room slight assymetry cause this? (the doors in the back of the room are angled and the silencers are not centered - they are slightly to the left because of the angled doors) Or is it more probable that one of the speakers is not floating correctly?



Martin


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PostPosted: Tue Jul 03, 2018 7:21 pm 
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The soffit wall is almost completed - only fabric frames are missing, they will hide the mineral wool that's still showing:

Attachment:
soffit_completed_smallsize.jpg


I'll put bigger LCD screen in the middle cut-out, once the acoustic structures will be finished.

The measurements are here:
Soffit completed

I never was was a "bass head", but what the soffit did for the bass frequencies is quite impressive - I couldn't stop listening to the music last night ;)
Also, the left-right and front-back space these mounted speakers create can't be touched by my smaller desktop monitors and I guess it will only get beter after the first reflection points will be treated.


Now on to the back wall treatment...


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PostPosted: Wed Jul 04, 2018 7:51 pm 
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In the meantime I was thinking about ceiling and this simple idea looks promising (cross section of the ceiling):

Attachment:
ceiling_plan.png

The angled 4" thick mineral wool slabs will act as broadband bass traps and will hide the air ducts. The 4" thick cloud will reduce unwanted reflections and will act as bass-mid absorber.
Given that the room is rather small I think it's highly probable that more than half of the surfaces will have to be covered with absorbing materials so I may as well cover the the entire ceiling this way...


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PostPosted: Thu Jul 05, 2018 7:11 am 
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Just checking here, but you did leave ventilation slots in your speaker enclosure box, right? You do have a deep, clear air path up behind the speaker itself, inside the enclosure box, at least a couple of inches deep? I couldn't see that in the photos, due to the angle, but I'm assuming you did leave that gap?

Your REW data is looking pretty good, by the way, considering that there's no other treatment in the room yet. The re-mount and re-do of the hangers is paying off!

Quote:
There's still significant difference between left and right speakers. Could the room slight assymetry cause this?
Probably not to any great extent. Possibly some differences in the speakers themselves, or the way you are driving them, or maybe even differences in the soffits. But I would wait until the room is treated more, before worrying too much about that.

Quote:
I never was was a "bass head", but what the soffit did for the bass frequencies is quite impressive - I couldn't stop listening to the music last night
Yup! :thu: Soffits will do that for you, when done properly! :)

Quote:
Also, the left-right and front-back space these mounted speakers create can't be touched by my smaller desktop monitors and I guess it will only get beter after the first reflection points will be treated.
... and the rear wall! You'll start hearing impressive differences once you get the rear wall properly treated.

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In the meantime I was thinking about ceiling and this simple idea looks promising (cross section of the ceiling):
That would work, but I would not do the entire room with the center section in absorption. The sides: yes, definitely, and I would even put more insulation in behind the mineral wool: put some light-weight (low density) "fluffy" insulation in there, to fill up as much of that air space as you can.

I would also suggest doing a proper, hard-backed angled cloud over the mix position.

- Stuart -

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PostPosted: Fri Jul 06, 2018 6:49 am 
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Many thanks, Stuart, your input is greatly appreciated!

Quote:
Just checking here, but you did leave ventilation slots in your speaker enclosure box, right?

Yes, I did, no worries here.

Quote:
Your REW data is looking pretty good, by the way, considering that there's no other treatment in the room yet. The re-mount and re-do of the hangers is paying off!

That's so good to hear! It was a lot of work so I'm happy it was worth it :)

Quote:
I would also suggest doing a proper, hard-backed angled cloud over the mix position.

Will do that - thanks for the suggestion. I'm thinking using 18mm plywood plus 10cm thick mineral wool. The angle will be calculated to create RFZ zone in the mix position.
I see the clouds are usually hanging on the chains from the ceiling. I'd like to attach the cloud to the soffit wall and to the lightning channels. Would that work?

Quote:
... and the rear wall! You'll start hearing impressive differences once you get the rear wall properly treated.

I was thinking about the rear wall and because how small the room is I think that any kind of diffuser is just not going to work properly. So the only idea I have is to fill the area below the silencers with the mineral wool (30 cm thick - the thickness of the lower silencer):
Attachment:
back_wall_30cm.png


Or maybe add another 10cm to cover the lower silencer (40 cm thick total):
Attachment:
back_wall_40cm_with_door.png


Would it make any sense if I tried to make the rear end more symmetrical like this?
Attachment:
back_wall_symmetry.png


I'm thinking that probably not - the gain in the symmetry would be smaller than the loss of the corner bass trapping?

Many thanks, once again!
Martin


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PostPosted: Wed Jul 11, 2018 1:43 am 
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Just finished the absorptive back wall with 45cm of mineral wool:
Attachment:
back_wall_stitch_small_color.jpg


The measurements are here: Back wall

Comparing the baseline measurement with this one shows that low end(<100Hz) is much more under control - it seems at least something is working ;).

There's still a lot of fluttering echo in the room caused by long parallel surfaces (both walls and ceiling/floor) that needs to be addressed.


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PostPosted: Wed Jul 11, 2018 1:58 pm 
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Major improvement with that rear wall insulation! I'm really enjoying seeing this build come together.

How is your HVAC working out? How is your isolation?

Greg

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PostPosted: Thu Jul 12, 2018 3:36 am 
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Major improvement with that rear wall insulation! I'm really enjoying seeing this build come together.

Thank you for your kind words! I'm enjoing the build very much - especially now, when the results start showing. I'm no expert in interpretation of the graphs from REW, but simple listening to the music speaks a lot - I enjoyed hours there already, even though the room is still very rough looking.

Quote:
How is your HVAC working out? How is your isolation?

This works very well, thanks to Stuart's design. I have around 50dB of isolation - I'm pretty sure it will be possible to comfortably record voice or guitar there without noise from the house sneaking in. And also to play electric guitar in the middle of the night without disturbing neighbours :)


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PostPosted: Fri Jul 13, 2018 8:50 pm 
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I would also suggest doing a proper, hard-backed angled cloud over the mix position.


I spent some time playing with raytracer plugin in sketchup. It seems that due to limited height of the room I'll be forced to make the hard backed cloud using 3 different angles:
Attachment:
cloud_raytrace.png


It could be three separate clouds but due to limited space I think I'll try to build it as one cloud by attaching 3 plywood pieces at an angle to each other.


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PostPosted: Sat Jul 14, 2018 3:35 am 
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You don't realize how nice a taller ceiling would be until you start ray tracing hey???!!!!

Here's mine:
Attachment:
Vertical Ray Trace.jpg

Ignore the horrible colors. I made square components and wanted to visually see each one.

Remember, the really off-axis rays should be traced to the hard backed surface of the clouds as they will be low cycle information. High frequencies are more directional.

Greg


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PostPosted: Sat Jul 14, 2018 5:10 am 
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You don't realize how nice a taller ceiling would be until you start ray tracing hey???!!!!

Heh, exactly :) Well, I'm stuck with my small room so I'm just trying to make it the best it could be.

I'm really jealous of the space you have available, Greg!

Martin


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PostPosted: Sat Jul 14, 2018 5:22 am 
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Move your cloud further back into the room, Martin. It does not need to go tight up against the soffits. The sound radiated at 90° off axis is very low frequency, and won't be reflected too well by a cloud. Just let it go up to the ceiling, where you need thick absorption to help damp it.

With the cloud a bit further back, you'll find that your angles work out a bit better.

- Stuart -

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PostPosted: Sat Jul 14, 2018 7:43 am 
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I feel like I'm hijacking this thread. Sorry! But Stuart, that's an awesome suggestion! I never thought of that before, but yeah, my black cloud section can totally just be insulation without the hard backing!

Thanks, as usual!

Greg

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PostPosted: Sun Jul 15, 2018 3:22 am 
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Move your cloud further back into the room, Martin. It does not need to go tight up against the soffits.

Quote:
Stuart, that's an awesome suggestion!

+1 Many thanks, Stuart!
That's exactly what I was struggling with - how close to the middle part of the soffit (which is even more up front than the speakers on both sides) should the cloud be placed. I'll move the cloud some 20cm back into the room and see what happens...

Quote:
I feel like I'm hijacking this thread. Sorry!

Don't worry, Greg, at all - your ideas just started a couple of my own!


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