Opinons wanted

Discussion in 'Speakers' started by Victor Ferguson, Jul 26, 2005.

  1. Victor Ferguson

    Victor Ferguson Stunt Coordinator

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    Here is what I have.
    H/K 335
    Polk RTi8's for Left and Right (tested response in room -3db limit of 34 hz.)
    Polk CSi5 for center (tested response in room -3db limit of 50hz.)
    Polk Rti4's for side and rear surrounds (tested in room response -3db limit of 55hz.)
    Polk PSW 404 (tested in room response -3db limit of 28hz)
    Items that may be of help in coming to a conclusion that I have....
    BFD
    Ratshack SPL meter
    1hz Test tones
    Room type.
    Room is 18x20x8, hard wood floors, large rug covering 75% of floor, hallway attached to room is approx 3x20x8.

    What I would like an opinion on is the use of the sub and how I should manage my crossovers. Obviously my sub does not compare well with the response of my other speakers but at this time another sub is not doable. I have read numerous articles about what is the best solution.. Some say to cross it all over at 80 others say to use the -3db limit of your speakers for setup.. it goes on and on. I have been trying to get my sub integrated into my system for a very long time and I am still unhappy with the integration. I'm about to the point of just unhooking the sub and excluding it all together. Below are the scenarios I've tried so far and the results:
    All speakers crossed over at 80hz. Sub eq'ed with BFD.
    Results: Sounds o.k... Soundstage seems to suffer alot and alot of the lower midrange bass is not nearly as detailed. Overall sound seems to be lacking depth and punch.
    All speakers crossed over at 60hz. Sub eq'ed with BFD.
    Results: Sounds a little better, soundstage is better than when crossed over at 80hz. Lower mid bass is cleaned up alot and has more presence.
    Mains set to large, the rest to small and all crossed over at 60hz. Sub eq'ed with BFD
    Results: Sounds the best so far. Soundstage is very wide and detailed. Lower mid bass is very good.

    Bass response is much better from my mains than from my sub. The sub is not a very good one and without the BFD its FR is horrible. However, I do need a sub in the system as it is apparent when there is very low bass that it is missing.

    Should I cross over at 40hz?

    If so then what about my surrounds and center they can't go that low? I have the ability to cross individual speakers over at different points but have heard you put gaps in your FR if you do so, so would that be a good option?

    The less I use the sub the cleaner the sound is but I also loose low freq response as a result, ( I realize it only goes about 5-6 hz lower than mains but it is noticable difference in scenes with low bass and when listening to some music with heavy bass) Where would you draw the line between muddying up your midrange and getting lower extension?

    With all the different scenarios I've tried I've always used the BFD to try and flatten out response and usually get just about everything +/- 3db with a couple trouble spots that are room induced being the exception. However, it always sounds different even though FR charts look very similar, is this normal?

    If I run my mains as large and send them bass using a L/R + LFE setting will the real low bass in movies and other content potentially harm my speakers?
    Sorry for the long post but any help and your opinions are appreciated.
     
  2. Phil A

    Phil A Producer
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    The first thing I'd do is put the SPL meter to use in getting a rough estimation of where the mains drop off with no sub. You can download test tones like: http://mdf1.tripod.com/test-tones.html
    or if you want to get a bit finer you could buy a test disc like: http://www.delosmus.com/cgi/cart/ite...05861122418900
    (you can buy it a bit cheaper at other online sites).

    Then with the SPL in the listening position hook up the sub and try different crossover settings and see what the differences are. You can try many of the different things you suggesting and after getting the bass as good as you can re-listen with your favorite music and movies and adjust to your taste. You can get it a bit finer if you get your hands on a good real time analyzer.
     
  3. Victor Ferguson

    Victor Ferguson Stunt Coordinator

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    I have listed -3db drop off for all speakers in my origional post. I have tested FR with sub at differnt x-overs as well as positions and EQ'ed at them all. I have had this same thread going over at AVS as well. I have tried all of the things you mentioned above except for getting a real time analyzer (its about three items down on my to get list with a new sub being number 1 [​IMG]
    Thanks for your reply.
     
  4. Phil A

    Phil A Producer
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    Victor, that -3db point is the manuf. rating under test conditions and not in your room. I have a real time analyzer and have tested not only the speakers in 3 of my systems but many others and every room is different. Sometimes moving speakers even several inches can make a big difference from the listening position. There are so many variables that start with the speaker design itself, position of the speakers, size of the room, construction materials of the room, furnishings of the room, electronics used, etc., that using manuf. specs in many cases is not accurate. That's why there are sites like rivesaudio.com (which may have helpful info for you too) and others where people sell consulting services to optimize system responses.
     
  5. Victor Ferguson

    Victor Ferguson Stunt Coordinator

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    I have tested them in room and thats what I got. I peformed 1hz measurements using a rat shack meter (using corrected values) , real traps test tones and plotted them. Some did better than manufacure ratings. Point is I have tested in room and with my room thats what I got.
     

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