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Started building my (small) studio

Discussion in 'F.O.H.' started by Eduardo Apolonia, Dec 3, 2006.

  1. Soundlurker

    Soundlurker Member

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    Wow, all these experiments must have been a huge pain the a.. but I'm sure it's worth it. I wouldn't have settled for this kind of response too.
     
  2. Metaltastic

    Metaltastic Member

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    Badass Glenn, so you did it yourself then?

    Ah, that must be why they offer a separate sub, I had been wondering...
     
  3. Glenn Fricker

    Glenn Fricker Very Metal &Very Bad News

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    Myself, and a very good friend. We went through about six diagrams before we decided on what would work. ...Then traced everything out on the floor before one piece of wood was cut.

    [​IMG]
     
  4. Eduardo Apolonia

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    I did try it removing the low density wool behind the Rockwool panels.
    One of the options being considered are tuned basstraps.


    Thanks [​IMG]


    I should have done the acoustical correction before installing the gear and started working.
    But I was in a hurry to have it ready, because I had work that was terribly late so I decided to go ahead and knew that I had to return to this point afterwards.
    I never thought that I would be so unlucky to have that hole around 90-150Hz. That's a extremelly important region in my opinion.

    That's one of the options I'm considering.
    The problem is that I have the Barefoots and to flushmount them (if that is possible, I never seen any) I have to disable the side woofers, so I would have to buy a Sub.
    It would be a waste.
    I'm going to try the Adams S3X-H and S4X-H and maybe a pair of ATCs and Dynaudios M2s or M3s.

    Besides the pics I made more than 100 different measurements. :loco:
    I'm working at full on this to get the problem corrected, and I've been extending my acoustics knowledge.

    I'm going to sell my Adams but as I said above I'm going to try the new ones.


    [​IMG]

    Thanks for the diagrams and raising this point.
    I'm aware of that.
    It's one of the options I'm more inclined to.
    I just have 2 (possible) problems with it:
    - The room was not designed with that in mind so I'm not sure if the side windows will be a problem. (Just have to do the mirror test, didn't buy a mirror yet to do it :oops: )
    - I will be at a bigger distance from the monitors, it will be more like midfields, so I will lose some volume headroom because the monitors will have to be louder to reach me at the same volume as before. And being farther away the room will have more influence.


    If I go that way I will have the acoustical consultant or Martin make the plans for it. Each one of them is capable of doing an excellent job as I have seen.
    About the Barefoots, I explained my concerns and thoughts about that above.

    That's one of the main reasons why I decided against it when the project was made, I didn't knew at that time which monitors I was going to buy and the problem if I changed monitors.


    I didn't knew that the Sub on/off switch was done with that in mind. Thanks for sharing that info.
    I always thought that it had the tweeter, mid and Sub on/off switches just for troubleshooting.
     
  5. 88mph

    88mph manbearpig

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    is it just me who feels like a desperate worthless noob whenever this thread shows up? :)
     
  6. crillemannen

    crillemannen Member

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    Hi,

    I had the same problem in my studio, that cut-out around 100hz and the problem was in the ceiling. So we laid drywall on the second floor and that actually even out the bump. Sorry for my bad English

    Good luck
     
  7. covil

    covil johny bigode

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    Hey Eddie I´ve had the same problem!
    Remember that changing monitors or their placemenent won´t do anything drastic to that big valley you have that is swallowing your 120 hz region. I´m shure that going around the room you will find some better or worse places, however you will never be able to completly remove those problems. Sorry that´s the conclusion i´ve had with my room.
    So i´m sure you already know that´s your room who is causing it. If you don´t know were´s the problem try this:

    http://www.mcsquared.com/wavelength.htm
    Insert the frequency that is causing you trouble and look at your room to find those distances.
    I don´t know your room but it could be the ceiling height without enough absorption on that particular zone.
    Rockwool just hanging won´t do much in that area.

    For 20/ 50Hz plasterboard with air gap sealed
    For 180/ 500Hz non-parallel surfaces +- 12º angled apart
    300 hz up - roockwoll, fiberglass, waste felter...

    That lives us with that 70/180Hz problem!


    Try something i´ve read, it worked for me:

    On your bass traps add , ideally PKB2,wich is a membrane, it has to be air tight otherwise it won´t do anything, or almost nothing!!
    If you don´t want to expend much money and wait for that membrane you could try simple roofing membrane and see if that will afect something. Use it with that plywood you have and build a gobo with that membrane facing front.
    REMEMBER AIR TIGHT!!! VERY IMPORTANT!!!

    So if anyone is using rockwool panels you should try measuring your room with and without and see if that does anything on bass!
    If it does- good for you!!
    If it doesn´t- Sorry dudes, bad news- you need much more treatment on room, and i don´t mean adding more rockwool.....
     
  8. covil

    covil johny bigode

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    Eddy, i´m sure you know most of the stuff i´ve writen, or all of it, but for those who doesn´t ,try it you will be surprised. I´m not making this up!!!! I have two books to prove it!! 500+ pages on acoustic. And tried it on my small studio,wich in the begining is always the worst case to start working!!!!!!:erk:

    Soffit mounting - is what i´ve used but your problem seems to be some place else!! And it boosts your low end at about 3db to 6bd. But it is a linear boost not a peak boost. Most speaker have a way to deal with that!!!
     
  9. Eduardo Apolonia

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    Hi Covil,

    First of all thank you very much for taking your time to give your opinion about it.
    I like to hear everbody's opinion. They're all valid to me. :kickass:

    About the speaker placement, actually one of the worst problems I have is caused by the speaker placement. The problem is what is called SBIR (Speaker Boundary Interference Response) or Allison Effect.
    The first person to make me aware of this effect was Barry Ober from http://www.soundoctor.com, I contacted him because of the JL Audio Subwoofers and he made some huge comments about my problem, and possible fixes, and also sent me a test cd. He did all this and I didn't buy him anything.
    Excellent service!!!!

    This SBIR is caused by the distance (1/4 wave length) from the woofer to the near walls, ceiling and floor.
    You can read about it in this RPG pdf
    http://www.rpginc.com/news/library/PS_AcD.pdf
    and on the GIK website:
    http://www.gikacoustics.com/education_sbir.html

    In my case the distances from the back wall, side wall and ceiling from the woofer are almost the same, one of the measurements I did was a scary coincidence, the measurements showed differences of this 3 points of only 2cm!!!! as you can see in this pics:

    [​IMG]



    [​IMG]

    84cm is 1/4 length of 102Hz.
    That is +/- where I have the dip.

    Then the length of my room creates a dip mode of around 105Hz if I remember well.
    The width of the back of the control room creates a dip mode at 107Hz

    The crossover of the sub to the mids woofers in the Barefoots is at 110Hz.

    So it's a hand full of bad coincidences.

    Thanks for your tip about the ceiling.
    The use of a basstrap with a membrane was one of the first solutions given by Martin Pilchner.

    I'll keep this updated for the possible solutions.
     
  10. covil

    covil johny bigode

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    I´m glad to help anyone who´s an audio freak like me!!!
    If you need any info on making that bass trap with a membrane, say something!!!
    If you keep that structure of your bass traps modifying it should very simple.
     
  11. GeertSamuel

    GeertSamuel Member

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    So how is it comming around? Allready satisfied?
    Apparently the Adams where obsolete?! :)
     
  12. Eduardo Apolonia

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    Thanks for your help offer, I appreciate it :kickass:

    I'm still at the same point :erk: , I've been waiting for different monitors to test. I'm going tomorrow to get a pair of S3X-Hs and S4X-Hs to test in the studio and on the end of the week I'm going to start the treatment.
     
  13. Hotstuff

    Hotstuff Member

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    Hi Eddy,

    When I first saw your acoustic treatments I found it strange that you did not address the two back corners and the door in the corner was a bad option. You should think about putting up some traps in the corners like Real Traps (or DIY) and see if it will help resolving the problem you have at the moment, putting up some traps on the wall ceiling corners is also a good option, for example the ceiling corners on the flank walls of the listening position.
    Make yourself 6 and do some experimenting.
    On the right hand corner you could make a permanent solution by fitting 2 corner bass traps permanently but on the door corner you will have to ether make them movable or set up a system that will guide the trap back and forth as you open and close the door.
    Those two bare corners dont make sense to me and should have been treated in the design faze.


    Your room doesn´t look very deep but perhaps you could fit a 2 seat couch at the back, this could play a role in evening out the bass response.

    Good Luck

    Hotstuff
     
  14. arvoitus

    arvoitus Member

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    This thread ... your life ... your dedication ... This is just incredible, i just have to give you my best wishes!
     
  15. Eduardo Apolonia

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    Hi

    First of all thanks a lot for your help. I really appreciate it!! :kickass:

    Now for some answers.
    There is an explanation why the control room does not have basstraps on the back corners.
    When the studio project was made I asked for it to be ready for surround and I also wanted 2 big windows (1 for the recording room side and 1 for the outside of the building to get sunlight in.
    This had a consequence, the last place to have a door was next to the back corner, so there isn't any treatment there.
    The side basstraps were also a lot bigger on project than what was built, I bought a lot of gear since the project was made so I needed room for the racks, so I had to cut the basstraps depth to open space for the racks.

    The front wall ceiling corners had already a basstrap that was done from the floor to the ceiling.
    The back ceiling corners haven't got anything as the entire corner.

    I'm doing a lot of testing at the moment with rockwool panels and those tests are on the list to be done, I didn't thought of putting Basstraps above the windows for testing, if that is what you are suggesting, thanks for the tip :)



    I thought of that too. :)
    And I thought about a mechanism to have a sliding Basstrap.
    Then googled if anybody had the same idea, and there it was on youtube a movie of the mechanism I idealized :lol:

    I never bought the couch because I knew that I would have to change the basstraps sooner or later, so I would need a lot of room space to work inside the control room at this point, so the couch would difficult the correction working.
    Although I know that the couch would help to even the bass response.
    Or not... :cry:

    Thanks again for the help. :)
     
  16. Eduardo Apolonia

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    Thanks a lot for the kind words :)
     
  17. Hotstuff

    Hotstuff Member

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    Hi,

    Yes this is what I meant at a 45º angle between the wall and the ceiling.The ceiling wall corner is an effective place to put bass traps.

    I also think a big acoustic cloud is better than smaller ones above the listening position and angled down towards the front of the room.

    Do you have 10x60x120cm fabric wrapped rockwool acoustic panels to do testing?

    On the back wall left side you could just hang a panel on the door with a 10cm spacer behind it and put one on the wall to the right of the door also with a 10cm spacer, a space behind the panel makes it more effective at lower frequencies , and then put a panel across the corner above the door so that it covers the ceiling and wall corners, for this you will need a small 10x60x60cm panel.

    Perhaps you could make some acoustic hangers to put behind the corner bass trap on the right hand side back corner.

    Unfortunately all the treatments you add might only just scratch the surface of your problem because the whole structure could be resonating at the problem frequency and canceling that frequency out. (This is just a theory cause I didn´t study acoustics and have no scientific knowledge to back this theory)

    Hotstuff
     
  18. Eduardo Apolonia

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    Finally some updates on the process.
    This is going to be long, I've been on this process for 4 months now. :oops:

    These graphs are only a small selection of the measurements I did in the past 4 months.

    I did more than 300 different measurements!!!!!

    As you can see the 100-130Hz dip is always there, sometimes wider some times narrower but it's always there grrr

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    I'll continue on next post...
     
  19. Eduardo Apolonia

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    The Portuguese Adam distributor Audiolog lent me a pair of S3X-H and S4X-H to try. I'm going to replace my Barefoots.
    I have to express my gratitude to the excellent customer service Audiolog as served to me. I have these 2 pairs with me for almost 2 months now!!!
    I hoped that the problem would be solved by the time I got the Adams but it didn't happen, and the distributor has let me keep the Adams in the meanwhile.

    I don't usually do publicity to distributors/dealers, but when a service like this is given I can't let it pass without giving it's recognition.
    Audiolog


    Back to measurements:

    So I changed to the Adams S4X-H.

    These are the monitors I used for the measurements, they're in different positions. I left them like this on purpose to check how they would react differently.
    The left one is completely outside the Basstrap and the Basstrap has 9cm Rockwool panels 70Kg/m3 panels installed behind the monitor. Behind the panels, there is also low density rockwool filling 1/2 of the Basstrap.
    The right one is inside the Basstrap space but it doesn't fit all inside, so part of it is outside the Basstrap line

    [​IMG]



    Back Basstrap before I placed any Rockwool packs inside
    It is currently with 9cm of Rockwool 70Kg/m3 panels but no low density behind.

    [​IMG]

    Rockwool panels packs placed on the back.

    [​IMG]


    Left Monitor
    Red Line - Before Rockwool packs
    Green Line - After Rockwool packs

    [​IMG]


    Right Monitor
    Red Line - Before Rockwool packs
    Green Line - After Rockwool packs

    [​IMG]

    The difference is not much as I expected, this is a monstrous basstrap, and the dip is still there.


    I made the test again but this time with the packs opened, and reaching the ceiling. It didn't made so much of a difference comparing with the packs unopen

    [​IMG]


    Just a reminder that the monitors are in different positions:
    The left one is completely outside the Basstrap and the Basstrap has 9cm Rockwool panels 70Kg/m3 panels installed behind the monitor. Behind the panels, there is also low density rockwool filling 1/2 of the Basstrap.
    The right one is inside the Basstrap space but it doesn't fit all inside, so part of it is outside the Basstrap line


    Left Monitor
    Red Line - Before Rockwool packs
    Green Line - After Rockwool packs

    [​IMG]


    Right Monitor
    Red Line - Before Rockwool packs
    Green Line - After Rockwool packs

    [​IMG]


    To continue...
     
  20. Eduardo Apolonia

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    Another test I did before:

    I made a test dragging one rockwool stack to the side. I didn't took any pic so I did a bad photoshop :) of the pics for you to have an idea of what I did.

    [​IMG]


    These were the measurements:


    Left Monitor
    Red Line - Rockwool piles centered in the room
    Green Line - Right Rockwool pile moved to the right next to door
    (didn't made much difference)

    [​IMG]



    Right Monitor
    Red Line - Rockwool piles centered in the room
    Green Line - Right Rockwool pile moved to the right next to door


    [​IMG]

    More to come...
     

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