Latest results from the control room from Hell, Any Suggestions???
Beano Bean
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#1
28th December 2012
Old 28th December 2012
  #1
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Latest results from the control room from Hell, Any Suggestions???

Hi All,

OK, i have followed advice sought on here and other forums and have adjusted the following.

I have installed a smaller table, placed an absorber on the rear wall behind the shelves, Measured the seating position at 38% of the way across the room (from the headhight position of the slant to the shelves), made an equilateral triangle between each monitor and ear position, made sure the desk is exactly halfway across the width of the room and the monitor speakers are the same distance from each wall. I have also swapped my Alesis M1 Active MKII's temporarily for my Alesis M1 Active 520's (As they have a proximity switch on the back to set the distance between the walls, this is set to 2 (close to walls)).

Here are my results :-

Full left speaker waterfall (40 Hz - 20 KHz)

http://www.flickr.com/photos/thechem...in/photostream

Full Right Speaker Waterfall (40 Hz - 20 KHz)

http://www.flickr.com/photos/thechem...in/photostream

Left Speaker 60 Hz - 600 Hz

http://www.flickr.com/photos/thechem...in/photostream

Right Speaker 60 Hz - 600 Hz

http://www.flickr.com/photos/thechem...in/photostream

Left Speaker 500 Hz - 900 Hz

http://www.flickr.com/photos/thechem...in/photostream

Right Speaker 500 - 900 Hz

http://www.flickr.com/photos/thechem...in/photostream

Left Speaker 900 Hz - 10 KHz

http://www.flickr.com/photos/thechem...in/photostream

Right Speaker 900 Hz - 10 KHz

http://www.flickr.com/photos/thechem...in/photostream

Left Speaker Reverb Time

http://www.flickr.com/photos/thechem...in/photostream

Right Speaker Reverb Time

http://www.flickr.com/photos/thechem...in/photostream

Room Front View

http://www.flickr.com/photos/thechem...in/photostream

Room Left Wall

http://www.flickr.com/photos/thechem...in/photostream

Room Right Wall

http://www.flickr.com/photos/thechem...in/photostream

Room Rear Wall and Door (Left)

http://www.flickr.com/photos/thechem...in/photostream

Room Rear Wall and Door (Right)

http://www.flickr.com/photos/thechem...in/photostream

Front view Ceiling

http://www.flickr.com/photos/thechem...in/photostream

I can see there are major problems around 80 - 100 Hz (almost a 30 db Dip), 300 - 400 Hz, and smaller around 600 and 800 Hz. The reverb time graphs i am afraid i do not really understand so apoplogies there.

Treatment wise as you can see there are superchunk basstraps in each corner and absorbtion panels and the side walls and one in the middle of the front, slated wall. I have had to use foam elsewhere due to weight restrictions as the absorbers couldn't either be nailed in due to the metal panel behind the walls (BA 13 with resonant cavities) or the weight ripping the plasterboard out of the window plug. There are also 2 absorbers on the celing, creating the hard surface/soft surface between the ceiling and floor (The floor also has resonant cavities).

I will maybe build some diffusers and put them on the side walls and the door, thus helping the room sound less dead. I am not sure what to do about the air pressure like problem (where even low level sound causes ear fatigue even in a short space of time (like being in a tunnel or on an aeroplane).

If anyone needs anymore info, please let me know.

Also, the room measures 3.6 m (Length), 3.2 m (Width) and around 2.2 m (Height). This is not including the slant (Floor Space).

As stated in previous posts, i am renting here temporarily so i cannot either adjust the walls and floors or spend out lots of money on tuned treatment.

If this is all i can do, then so be it, but if i could tweak it inexpensivley that would be great.

Thanks in advance.

BB
#2
28th December 2012
Old 28th December 2012
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cannot see any images. maybe the big dip is due to the floor-ceiling? or some additional seating-speaker positioning? maybe post the REW file (zipped)
Beano Bean
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28th December 2012
Old 28th December 2012
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Hi Glenn,

The links are now fixed.

The REW file is too big to attach (when zipped) though so i cannot attach it.

Thanks for the reply,

BB
jwl
#4
28th December 2012
Old 28th December 2012
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jwl
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If that were my room I'd add more bass trapping. Wall/ceiling corners and wall/floor corners.

Or, use this listening test to spot areas in the room that have bass buildups, and put bass traps in those areas: RealTraps - Filtered Noise
#5
28th December 2012
Old 28th December 2012
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Glenn Kuras's Avatar
 

Quote:
Measured the seating position at 38% of the way across the room (from the headhight position of the slant to the shelves)
38% is only a starting point. Try to move the mix spot forward or back to see if that helps. Over all though the low end decay times (sorry just a quick look) don't look all that "horrible".

Quote:
I will maybe build some diffusers and put them on the side walls and the door, thus helping the room sound less dead.
Adding diffusion really is not going to fix a dead room unless you replace absorption with it. What you may want to do is put wood slats in front of the traps you have now to help scatter/diffuse/reflect some of the upper frequencies back in the room.
Beano Bean
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#6
28th December 2012
Old 28th December 2012
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Quote:
Originally Posted by Glenn Kuras View Post
38% is only a starting point. Try to move the mix spot forward or back to see if that helps. Over all though the low end decay times (sorry just a quick look) don't look all that "horrible".



Adding diffusion really is not going to fix a dead room unless you replace absorption with it. What you may want to do is put wood slats in front of the traps you have now to help scatter/diffuse/reflect some of the upper frequencies back in the room.
Thanks for that Glenn,

As it is such a small room, moving the mix position has very dramatic results even by a few cm (there is less than 30 cm between 38% and 50 %).

When the room was set up before i changed the desk, the bass would completely disappear if i so much as moved my head right back and really boom if i moved it forward. A the moment even moving my head left to right a little seems to completely cancel out the sound from the opposite speaker.

I cannot move forward any more as the monitor speakers are touching the foam on the slant (I even had to lay them on their sides to get them to fit).

What i will do is as you suggested putting thin slats of thin fibrewood on the absorbers. How would i go about this so that it doesn't reintroduce flutter echo?

Thanks again,

BB
#7
28th December 2012
Old 28th December 2012
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Quote:
What i will do is as you suggested putting thin slats of thin fibrewood on the absorbers. How would i go about this so that it doesn't reintroduce flutter echo?
I would do a search on GS about slats over top of DIY absorption.
You want have a problem with flutter echo but I would not use them in the early reflection points.
Beano Bean
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#8
29th December 2012
Old 29th December 2012
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Quote:
Originally Posted by Glenn Kuras View Post
I would do a search on GS about slats over top of DIY absorption.
You want have a problem with flutter echo but I would not use them in the early reflection points.
Thanks for that Glenn will do.

I don't suppose you or anyone else knows of any Acousticians that reside around the Calais, France area that i could get in to have a look (and how much they would usually charge)?

Thanks again,

BB
#9
29th December 2012
Old 29th December 2012
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the left speaker measurement seems to show the significant dip whereas the right speaker measurement does not. couple of thoughts - swap the speakers left to right and re-measure; assuming the result is the same, speaker positioning - define your listening triangle size and move it side to side and forwards backwards to determine if you can improve the response. you probably need a massive amount of absorption on that back wall - consider framing in something around 300mm deep and basically leaving an opening for the door :-) then fill the frame with 48kg/m3 insulation and cover with cloth. add some narrow strips of wood to provide some minimal reflections.
Beano Bean
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#10
29th December 2012
Old 29th December 2012
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Quote:
Originally Posted by gullfo View Post
the left speaker measurement seems to show the significant dip whereas the right speaker measurement does not. couple of thoughts - swap the speakers left to right and re-measure; assuming the result is the same, speaker positioning - define your listening triangle size and move it side to side and forwards backwards to determine if you can improve the response. you probably need a massive amount of absorption on that back wall - consider framing in something around 300mm deep and basically leaving an opening for the door :-) then fill the frame with 48kg/m3 insulation and cover with cloth. add some narrow strips of wood to provide some minimal reflections.
Thanks for that gullfo,

I think the difference between speakers may have something to do with the length of the room on right being shorter than the length of room on the left (the basstraps on the right are closer to the seating position than on the left).

I have a small panel on the back wall at the moment behind the shelves. Maybe i could do as you have suggested build a bigger one on that wall behind the shelves and just use the shelf itself for the reflections? (As this is the only place in the flat i can have these shelves and they have all of my mics, cables, blank disc etc etc on them).

I have just placed some narrow slats of wood on the absorbers on the left and right walls, but it has added a short flutter echo in the room (as i was worried it would), but i was careful not to place them at any of the early reflection points so i hope that it won't matter too much.

As for the triangle/seating position i cannot change where it is as the speakers are right up against the wall at the moment so they cannot go in that direction. If i move them wider apart, it would mean moving myself further back which would put me at 50% of the way across the room, and it is here that the bass completely disappears (there is only around 30cm between 38 and 50%).

My only other option i could think of would be to move my seating position to 62 - 63 % of the way, but i would be very close to the back wall/shelves.

Thanks

BB
#11
29th December 2012
Old 29th December 2012
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If you want to test if you are getting to much flutter then play a clap (or what ever) through the speakers and listen. A lot of times if you just sit in your seat and clap your hands it gives a false perception.
Beano Bean
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#12
29th December 2012
Old 29th December 2012
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Quote:
Originally Posted by Glenn Kuras View Post
If you want to test if you are getting to much flutter then play a clap (or what ever) through the speakers and listen. A lot of times if you just sit in your seat and clap your hands it gives a false perception.
Ahh ok.

Once i have set the gear up again tomorrow i shall do that.

I was walking around the room and clapping in different places.

Thanks Glenn.
#13
29th December 2012
Old 29th December 2012
  #13
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Quote:
Originally Posted by Beano Bean View Post
Ahh ok.



I was walking around the room and clapping in different places.

Thanks Glenn.
You would be chasing flutter all day long. What mostly matters is what you can hear from the monitors sitting at the mix spot.
Beano Bean
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#14
30th December 2012
Old 30th December 2012
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I have just re set the gear up in there again and it now sounds 100 times worse.

When i sit in the mix position the sound dramatically changes even with the slightest head movement :-

If i move my head forward, the sound widenes and the ear pressure is worse.

If i move to the left the right channel completely disappears.

If i move to the right it also disappears, but not as bad.

If i move back it gets a little better, but if i move another inch the bass disappears.

I guess it's time for a pro
#15
30th December 2012
Old 30th December 2012
  #15
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It sounds like to me you are just moving in and out of nulls and peaks (mostly lower frequencies). Bass trap more corners is what will help.
Beano Bean
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#16
3rd January 2013
Old 3rd January 2013
  #16
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Eeeeeekkkkkk.........

The acoustician wants £950 just to come here and do a reverb time test.

Back to the drawing board.

On the other hand, i may be able to blag a loft space of my wifes grandma, on the downside it has 2 slanted roofs (as lofts do) but on the plus side it is around 70 square meters and is rectangular.

Is this worth looking in to???
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