Volume levels for 2 subs

Discussion in 'Archived Threads 2001-2004' started by Michael Eriksen, Nov 6, 2001.

  1. Michael Eriksen

    Michael Eriksen Stunt Coordinator

    Joined:
    Nov 18, 1999
    Messages:
    70
    Likes Received:
    0
    Hi group,
    I just got my servo-15 today and im trying to get it to work together with my Atlantic Technology 452 thx sub.
    I use it with the Denon av1-se.
    THX sub is always playing in THX mode which means no seperate sound level setting. I need the receiver set to +4 db on the .1 channel to get 80 db on the testsignal. Speakers are set to 75 db on the test signal.
    When I use the servo-15 alone, I only need to set the receiver to +1 db to be able to get the 80 db that I want. If I set the .1 channel to +4 db I have to turn the volume almost all the way down to be able to go down to the 80 db.
    Is it better in theory that the subs play at the same level. If that is so I need to turn the servo-15 volume way down because I then need the receiver to stand at +4 db to be able to get the thx sub to play out 80 db.
    Or will it be better to set the receiver at 0 or +1 db and turn the servo up a bit to get it to 80 db, which ofcourse means that the thx sub will play a bit below 80 db...around 75 db.
    Need feedback please...
    I can yet adjust the fase because I dosent get the x-30 before thursday, but I might as well start at the volume question..
    Thanks in advance..
    Michael Eriksen
     
  2. Clinton McClure

    Clinton McClure Casual Enthusiast
    Supporter

    Joined:
    Jun 28, 1999
    Messages:
    4,231
    Likes Received:
    331
    Location:
    Central Arkansas
    Real Name:
    Clint
    This could become an issue in itself by running two different types of subs on the same set-up. I'd figure the Servo 15 would be well enough by itself but I am not familiar with Atlantic equipment.
    What I would guess would be to set the receiver however you need it for the Atlantic to reach 80dB, then disconnect it (the Atlantic) and turn up the gain on the Servo 15 to make it also register at 80dB at the same volume you calibrated the Atlantic. Then you should be able to hook the Atlantic back up and have both outputting the same. This is only in theory, of course. Actual mileage may vary...
    Let us know what you find.
    PS: Why do you need a phase control for the subs? What is the placement of them in regards to your HT set-up?
    ------------------
    My DVD Collection Casa del Clint
    [Edited last by Clinton on November 06, 2001 at 03:48 PM]
     
  3. Michael Eriksen

    Michael Eriksen Stunt Coordinator

    Joined:
    Nov 18, 1999
    Messages:
    70
    Likes Received:
    0
    They are both placed in the corner closes to the listenig position and stacked on each other. That is next to and a little behind the left front speaker.
    Maybe there is no need for fase adjusting, i have to test it at different frequencies, but I still want the x-30 because it has other features besides the variable fase control.
    Thanks for the reply I will try that tonight.
    Michael Eriksen
     
  4. Clinton McClure

    Clinton McClure Casual Enthusiast
    Supporter

    Joined:
    Jun 28, 1999
    Messages:
    4,231
    Likes Received:
    331
    Location:
    Central Arkansas
    Real Name:
    Clint
    With subs in the position you describe, I do not think you'll want to phase them 180° out. But you can try it and it might sound pretty good. [​IMG]
    ------------------
    My DVD Collection Casa del Clint
     
  5. Michael Eriksen

    Michael Eriksen Stunt Coordinator

    Joined:
    Nov 18, 1999
    Messages:
    70
    Likes Received:
    0
    I dont want to fase them 180 out. I just want to play some frequencies between 20 hz-80hz and adjust the servo-15 so that it plays totally in fase with the Atlantic sub. The Atlantic subs plays in fase with the speakers.
    I do smell a problem however if the subs have a different fase at different frequencies but Ill have to test that.
    Michael Eriksen
     
  6. Luis A

    Luis A Second Unit

    Joined:
    Aug 2, 2001
    Messages:
    414
    Likes Received:
    0
    I don't see why anyone would need to have 2 subs set to 80db each. I have 2 M&K MX350 subs and have both set to THX and adjusted the lfe fro the preamp to 80db. That means both subs are calibrated individually @ 74db, together they are calibrated @ 80db @ ref level. I suggest doing something like this, you will always have the option of turning the bass up on your preamp later if you want more bass.JMHO. [​IMG]
    L
     
  7. Michael Eriksen

    Michael Eriksen Stunt Coordinator

    Joined:
    Nov 18, 1999
    Messages:
    70
    Likes Received:
    0
    Sorry, I didnt made myself clear. I want the 80 db when both subs are playing. Im adjusting the subs seperately to get them to play at the same level. I also choose 80 db for each sub seperatly and I then expected to turn down the volume on the pre-amp when they both are playing.
    Both subs are playing 80 db on the testsignal seperately.
    BUT when both subs are playing its still only 80 db....shouldnt that be a bit higher ? And should I be worried about something.
    There is definately more bass when I play movies. On the opening a toy story I reached about 112 db several times with the receiver at -2 db. With one sub I can get about 102 max with same settings.
    Michael
     
  8. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    The subs are being separately played by turning one or the other off rather than unplugging the input cable, right? Unplugging would alter the load on the signal and alter the results. Turning off won't alter the signal load so you should see a dB rise when the 2nd sub is activated. Since you don't measure an increase when both are active you must be getting a phase cancellation at the test signal frequencies.
    How does changing phase on one of subs alter the measured SPL level of the test signal? You should see a peak in measured SPL when the subs are in phase.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     
  9. Michael Eriksen

    Michael Eriksen Stunt Coordinator

    Joined:
    Nov 18, 1999
    Messages:
    70
    Likes Received:
    0
    I dont unplug the input cable. I just turn off the other sub. They are not connected with an Y-cable, but the Atlantic is directly connected to the receiver and the servo-15 to the Atlantics "though" plug.
    When I get the x-30 I will see if others results occur when I adjust the fase on the servo.
    Thanks,
    Michael
     
  10. Tom Vodhanel

    Tom Vodhanel Cinematographer

    Joined:
    Sep 4, 1998
    Messages:
    2,215
    Likes Received:
    8
    I'd also get a 99 cent *Y* linelevel splitter and run both subs off one leg. This will eliminate the variable of the AT *through* circuitry.
    You may need to play with the phase on the AT. have someone read the SPL meter at your seat and slowly turn the dial. Try leaving it on the setting that results in the loudest peak during the test tone signal.
    TV
     
  11. Luis A

    Luis A Second Unit

    Joined:
    Aug 2, 2001
    Messages:
    414
    Likes Received:
    0
    I apologize for the misunderstanding.
    I suggest getting a "Y" splitter as well. All you would need to do then would be to set each sub to 80db, but I think you should leave both subs "ON" and just turn down the variable on one sub when you are calibrating the other. Next you would turn both subs to where they measured 80db individually. Run sub test tone again and SPL should read between 84-87db. All you would have to do after is back the LFE off on the preamp until the SPL reads 80db. I'm not very good at explaining, but I hope it helps.
    Also its my understanding that if you have 2 subs stacked in the same location they should both run in phase. Is this correct?
    L
     

Share This Page