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PostPosted: Fri Oct 12, 2018 4:15 pm 
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Location: Bratislava, Slovakia, EU
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Yes, length same as the poly. I think you'll need to go deeper than just 1cm. Try with whatever scrap pieces you have laying around right now,. Anything will do, even if not rounded. Just stick them on with bits of duct tape temporarily, to see if they have the desired effect.


I tried this with some quarter-round planks, that I glued together to form half rounds (4.5cm wide, 2.2cm deep). Here's the result:

BEFORE:
Attachment:
Without_planks_R.jpg


AFTER:
Attachment:
With_planks_R.jpg


The reflections are still there, they are just much smaller. Would rebuilding the polys to "d" or "e" curve help me to achieve significantly better results?

Martin


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PostPosted: Fri Oct 12, 2018 4:25 pm 
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Let's see the actual MDAT... :)

Quote:
The reflections are still there, they are just much smaller.
Yup! So the concept is correct... maybe just not the dimensions... However, you did get a pretty good reduction there.


- Stuart -

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PostPosted: Sat Oct 13, 2018 1:32 am 
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Location: Bratislava, Slovakia, EU
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Let's see the actual MDAT... :)


Of course - here you go...

There are 4 measurements: 2 for L and 2 for R speaker, both with and without planks.


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PostPosted: Thu Feb 21, 2019 7:55 pm 
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Location: Bratislava, Slovakia, EU
I see the total count of the views is closing on 10.000 and I haven’t updated the status in a while. The progress slowed down a little as I had to go back to work after 4 months, but this is how the studio looked like at the end of the year:
Attachment:
front1.jpg

Attachment:
back1.jpg

Attachment:
left1.jpg

Attachment:
right1.jpg

I re-did the vertical poly diffusers to be of ‘D’-type curve:
Attachment:
poly-and-non-poly-cylindrical-buckled_end_constraints-shapes.jpg

This helped with the reflections I was dealing with in the previous posts.


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PostPosted: Thu Feb 21, 2019 8:00 pm 
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Location: Bratislava, Slovakia, EU
In the meantime I started to work with Stuart on the digital tuning, as he agreed the room was treated well enough / was ready for this next step. I wanted to process with the tuning before finishing the room with the fabric in case there would still be some additional treatment needed.

In the process Stuart noticed there’s still some flutter echo in the room. After analyzing the room (read: clapping and jumping around ) I noticed these were the problem areas(red):
Attachment:
left1_areas.jpg

The green ones are OK, because these parts of the walls are angled.
Because the room is very small and the space is at premium, I decided to try dealing with the flutter and effectively using the space at the same time. Two horizontal diffusers, guitar cases, a bookshelf and a small combo amp strategically placed in the problem areas:
Attachment:
left2.jpg

Attachment:
right2.jpg

It worked quite well and there’s no flutter noticeable anywhere in the room now. At the same time it’s now furnished like I’d like it to be and I have everything I need close at hand.

Hopefully the end of digital tuning process is near and I'll be able to share the results.


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PostPosted: Sun Feb 24, 2019 4:52 am 
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Even with just exposed insulation, it looks gorgeous! Great work dude!

Greg

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PostPosted: Sun Feb 24, 2019 8:55 pm 
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Thank you, Greg!

My daughter's friend (9yo) commented: what a cozy little room!
I'm tempted to leave it as it is :)


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PostPosted: Sat Apr 13, 2019 7:14 am 
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This has been one fast ride! For the last one and half month Stuart and I worked on the digital tuning of this small room. We exchanged emails almost daily, sometimes several times a day and now the room is finally ready. I'll leave it to Stuart to present and explain the graphs, I just want to comment on some small acoustic treatment bits that were added in the process of digital tuning.
There was a big dip (>20dB) in the frequency response at around 130Hz. It was not noticeable when listening to the speakers, but still the measurement showed there was some problem and with Stuart's assistance we found out it was a floor bounce. That's why there are those small towers of mineral wool on both sides of the mixing desk and also the angled plywood/mineral wool panel under the desk (kind of inverted ceiling cloud):
Attachment:
front_stitch_small.jpg


These solved the issue, now I only need to find a way to make them less ugly :) (and to cover the mineral wool with fabric panels to make the room more presentable...)

This whole process showed me that digital tuning is an amazing tool in the hands of an expert. And if it goes hand in hand with acoustic treatment of the room, of course. The results are much better than I dared to believe given how small the room and how unlucky the dimension ratio is (2:1:1)...

Big thanks to this amazing forum (and John and Stuart)!

Martin


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PostPosted: Wed May 01, 2019 5:37 pm 
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The tuning process is finished, so I'd like to share some graphs to show how this whole adventure ended (this is excerpt from Stuart's mail, he might want to chime in with some more comments):

Frequency response is now flat to within +/- 2.4 dB across the entire spectrum, 28 Hz to 21 kHz (1/24 octave smoothing):
Attachment:
FR_smoothed_1_24.png

And even better when smoothed to 1/3 octave, as required for international specs:
Attachment:
FR_smoothed_1_3.png

At that scale, we are getting +/-1.2 dB. For example, ITU BS.1116-3 requires +/-3 dB, and even then it's only from 250 Hz to 2 kHz... we get +/- 1.2 dB across the entire spectrum.

The Left and Right channels are within +/- 0.9 dB across the spectrum (1/3 octave smoothing). The same specification as above requires +/- 2 dB:
Attachment:
LR_speakers.png

The waterfall below 500 Hz is very smooth and flat:
Attachment:
waterfall.png

And the spectrogram shows the same: smooth and flat across the entire low end:
Attachment:
spectogram.png



After this the "house curve" was applied to make the speakers/room system sound more natural (more like our ears are used to hear things):
Attachment:
house_curve.png

The blue curve is the "flat" response, and the purple curve is with Stuart's House Curve applied You can see the slight bass boost and treble cut...
It took me some time to get used to it, but now I wouldn't get back to flat response.

Big thanks to Stuart for helping me making this a reality!

Martin


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PostPosted: Fri May 03, 2019 5:10 pm 
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Great work! Crazy good results! What processor are you using for eq?

Greg

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PostPosted: Fri May 03, 2019 6:48 pm 
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FBQ-2496, but it's crazy finicky to get right, and the manual is next to useless. There's also MIDI communications problems with REW that cause the data to not upload correctly sometimes... at random.... It does the EQ job fine, but I don' recommend it unless you are prepared to sit through the pain of trying to make it play nicely....

- Stuart -

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