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PostPosted: Wed Oct 10, 2012 10:16 pm 
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Location: Rome, Italy
ooook! So the next step will be building those superchunks in the corners. Will do that next week when I'll be back at the studio, then will update the topic with the new REW measurement.

About the odd calibration.... I didn't have an SPL meter so I skipped the levels matching part. But I adjusted the output level to a reasonable amount (before serious injury ehehehe).
Anyway, I'll get the meter for the next steps.

About the high end rolloff.... I suspect it's because there is still carpet on the floor. Not enough money to swap it for a wooden floor, for now.

Thanks a lot Stuart for your help. To next week for the updates!

Giacomo


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PostPosted: Wed Oct 10, 2012 10:40 pm 
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just a question about superchunks. in this case how should i do the upper termination?

the upper ceiling corner has an angled shape, as you can see on the pictures i posted.

is it ok to not building the superchunk up until the top, leaving some empty space in the upper corner?


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PostPosted: Wed Oct 10, 2012 10:50 pm 
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i
Quote:
s it ok to not building the superchunk up until the top, leaving some empty space in the upper corner?
Go up as high as you can, since the "tri-corner" up there where the ceiling and two walls meet is the best, most efficient location. Even if you just stuff some pieces of off-cut insulation up there in that strange shaped gap, that would still help.

- Stuart -

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PostPosted: Fri Oct 19, 2012 11:10 pm 
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updates:

- superchunks have been installed in the front corners.

- speakers are now placed as Stuart suggested: spaced 1.4m apart and against the wall as possible, with bass rolloff at -5.0dB.

- two panel absorbers have been placed on the right side, and one on the left. i've placed them against the wall as much as possible, is that ok or is better to leave some gap?

in the attachements you can find pictures of how the room is currently setup, and the rew files separate for the left and right speaker. i am waiting for the spl meter to be delivered, so the dB scale is not calibrated yet.
i see they are way too much asymmetric on bass frequencies, guess it's because of the asymmery of the back of the room (see sketchup drawing on previous page), but I really don't know how to deal with it.

there is no space for placing superchunks in the back corners too, because there are both the door and the electrical panel.
the idea at the moment is to place a curtain filled with wood, to mimic a wall, but I guess it wouldn't be relevant for problems below 150Hz.

what do you think?


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PostPosted: Fri Oct 19, 2012 11:28 pm 
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these are the measurements.


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PostPosted: Tue Oct 23, 2012 12:31 am 
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anyone?


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PostPosted: Wed Oct 24, 2012 12:04 am 
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I've made some more thoughts about improving the room.

The new idea is adding a wall on the back made with drywall and rockwool, and moving the main door there too.

Doing this would permit to place the speakers firing at the longest axis of the room, and with a good L/R symmetry. The concave surface will be less influent too...

What do you think about this?


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PostPosted: Sat Nov 03, 2012 11:43 am 
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I noticed that you don't have any absorption in the front wall, behind the speakers. You need that. A large panel, at least 4" thick if possible. That could be responsible for some of the issues you see.

You also do not have anything on the rear wall: You need a very large, very thick absorber on that wall. I would suggest 6" thick and spaced away from the wall by 6".

There is nothing on the ceiling, either. You need some type of ceiling cloud up there.

And yes, the difference between the left and right speakers are undoubtedly due to the rear of the room

Quote:
- two panel absorbers have been placed on the right side, and one on the left. i've placed them against the wall as much as possible, is that ok or is better to leave some gap?
Better to leave a gap, if you can.

Quote:
- speakers are now placed as Stuart suggested: spaced 1.4m apart and against the wall as possible, with bass rolloff at -5.0dB.
The speaker roll-off seems to be fine, although it is hard to say for sure, as there are so many other artifacts in the graphs.

Quote:
- superchunks have been installed in the front corners.
Excellent! They look fine, and are probably doing there job, but you still need more bass trapping in there.

Quote:
What do you think about this?
that looks like a very good possibility, and worth trying.

- Stuart -

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PostPosted: Sun Nov 04, 2012 11:53 pm 
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Hey Stuart,

I'll definitely make some more panels.

How much area for the front wall, back wall, and ceiling should I cover?

I am afraid putting too many panel would result in too much absorption at high and hi-mid frequencies. And there is yet carpet on the floor!

Which way can I space the panels from the side walls? And from the ceiling, it's all drywall and tends to be very weak if I put screws into it.

Anyway, this week I'll do that work on the wall and set up the room with the new layout. I hope that I'll get more symmetry in the frequency response. Will let you know.


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PostPosted: Tue Nov 13, 2012 3:48 am 
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Quote:
I'll definitely make some more panels.

How much area for the front wall, back wall, and ceiling should I cover?
What are the total dimensions of the room again? I know they must be in your thread somewhere, but I'm very tight on time, so it would help if you can just give me the overall length, width and height, then I can estimate the coverage that you will need.

Quote:
I am afraid putting too many panel would result in too much absorption at high and hi-mid frequencies.
When you build the absorbers, put a layer of plastic over the insulation before you put the final cloth on. That reflects the highs back into the room, while still allowing the lows to get through.

Quote:
Which way can I space the panels from the side walls? And from the ceiling, it's all drywall and tends to be very weak if I put screws into it.
You could build the treatment panels on stands, or use the "french cleat" technique:

viewtopic.php?f=10&t=17200&p=120869&hilit=+french+cleat+#p120869
viewtopic.php?f=10&t=12321&p=88090&hilit=+french+cleat+#p88090
viewtopic.php?f=2&t=14837&p=114430&hilit=+french+cleat+#p114430
http://www.buildthisroom.com/2010/tools ... cleat.html

Just put a 2x4 across the back of the panel before you put the french cleat on it.


- Stuart -

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PostPosted: Tue Nov 13, 2012 4:24 am 
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Hi Stuart,

I post you again the room drawing with the new layout. This week I'll do the work on the wall and moving the door, and I'll upload new pictures after that.

Room internal dimensions will be 2,46m wide x 3,40m deep x 2,40m high

Tips for the plastic on the panel and the french clear are great!

Thanks again for giving help. Stay tuned for upcoming pictures and rew measurements after room modification!

Giacomo


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PostPosted: Tue Nov 13, 2012 6:43 am 
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Quote:
Room internal dimensions will be 2,46m wide x 3,40m deep x 2,40m high
OK, theoretically you need a total of 237 sabins of absorption for that room, which means the equivalent of 22 square meters of open window. (A window that measures one square foot has exactly one sabin of absorption. One square foot is about 930 square centimeters).

So, you need at least 22 m2 (square meters) of "perfect" absorption in that room. The total surface area (all walls, floor and ceiling) is about 42 m2, but the floor and doorway take up about 10 m2, so you have about 32 m2 of possible surface. So you need to cover about two thirds of the entire surface area of the room.

The front wall is about 5 m2, and so is the rear wall, so if you cover those completely then you have about half of what you need. If you do a ceiling cloud of about 4m2 then you should be getting close to the right amount of absorption, (considering the treatment you already have on there).


- Stuart -

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