Sub / room compatability

Discussion in 'Archived Threads 2001-2004' started by Kevin Beck, Jun 14, 2002.

  1. Kevin Beck

    Kevin Beck Stunt Coordinator

    Joined:
    Jan 4, 2001
    Messages:
    249
    Likes Received:
    0
    Trophy Points:
    0
    Looking for insight as to wheather a specific sub configuration,..ie. sealed tuned to 25hz. or very large ported tuned to 16hz. will perform vastly different, in one room over another. In other words,..is there any thought to matching a style, and tuning to the room it will be used in? Then,...because it seems to me a reasonable idea. (I know car audio SPL people do it to get the most from a given cabin.) Just how would you determine what to build?
    Heres the deal,..I'm having problems with a sub I built. In the room,..its just not impressive,....upsairs, when its playing,...it seems if the house is going to colaps. Well,..not quite that bad,..but you get the idea. I figure there is a way to design a sub for a given room. Just don't have a clue as to how to go about it. Any info on this?
    Thanks >>>--->
     
  2. Wayne A. Pflughaupt

    Moderator

    Joined:
    Aug 5, 1999
    Messages:
    6,207
    Likes Received:
    56
    Trophy Points:
    9,110
    Location:
    Katy, TX
    Real Name:
    Wayne
     
  3. Kevin Beck

    Kevin Beck Stunt Coordinator

    Joined:
    Jan 4, 2001
    Messages:
    249
    Likes Received:
    0
    Trophy Points:
    0
    Wayne,..
    My main question was if it was much of a normal thing to try matching a sub to a room, given the chance. As you mentioned, a lot of subs out there are store bought, and tweaked after they get wherever they are headed. The coment about the different rooms was just an observation I guess. The theater is in the basement. The output down there is minimal. It seems to have little boom, as well as little shake and rattle. Upstairs though, right above the theater, thing are going crazy, shake and rattle wise. I realize the concrete floor will lesses some effect, but it sure seems as if it should be acting different than it does.
    >>>--->
     
  4. Wayne A. Pflughaupt

    Moderator

    Joined:
    Aug 5, 1999
    Messages:
    6,207
    Likes Received:
    56
    Trophy Points:
    9,110
    Location:
    Katy, TX
    Real Name:
    Wayne
    Kevin,

    It may be that there are just more things to shake and rattle upstairs – picture frames, knick-knacks etc. – that are (hopefully!) not present downstairs.

    Not to mention, in the HT room the main speakers will tend to mask such noises. Upstairs there is not the benefit of that, so any rattling will seem louder than it does downstairs.

    Where is the sub’s placement in the room (corner, etc)?

    Where is the primary seating position – middle of room, against back wall, somewhere in between?

    Is the sub substantial (no pun intended) enough for the size of the room? For instance, you can’t expect a single, small-diameter driver to deliver both high SPL and low extension in a huge room.

    Regards,
    Wayne A. Pflughaupt
     
  5. Kevin Beck

    Kevin Beck Stunt Coordinator

    Joined:
    Jan 4, 2001
    Messages:
    249
    Likes Received:
    0
    Trophy Points:
    0
    Wayne,..
    Thanks for the interest. Here is what right now. 480L dual Tempest Sonosub, tuned to 17hz. At the moment, powered by a little JBL digital amp from a PB12 sub, 250 watts total. The room is in the basement,15 X 20 with a small hall area at the back.Ceiling is 71/2 ft. Sub in front corner. Have tried a couple different locations as well. Main seat is in middle of room, about 15 ft. back from the front wall.
    Again, this is all first impressions. I have not run any type of Eq. in the past. Plan to in the near future, which may do the trick. In the mean time however, I am building a smaller enclosure, tuned a bit higher, just to do a little comparison.
    >>>--->
     
  6. Wayne A. Pflughaupt

    Moderator

    Joined:
    Aug 5, 1999
    Messages:
    6,207
    Likes Received:
    56
    Trophy Points:
    9,110
    Location:
    Katy, TX
    Real Name:
    Wayne
    Hmm, the sub us certainly adequate for the room. I could probably get a better idea what is happening if you had some 1/6-octave readings.

    I’ve found that most HT rooms sound best with a “house curve,” where response rises from around 100Hz and shelves at 32Hz.

    Considering your tuned frequency and the way you’ve described the sound, it appears to me that you have way too much energy below 32Hz and nothing above it – as if response is flat from 100Hz to 32 or 25Hz, then sharply rises below that point. The fact that everything in the room rattles shows it’s putting out some impressive energy, but most of it is too low to hear – only feel.

    Hope this makes sense.

    Regards,
    Wayne A. Pflughaupt
     
  7. Mike Strassburg

    Mike Strassburg Second Unit

    Joined:
    Nov 4, 2001
    Messages:
    421
    Likes Received:
    0
    Trophy Points:
    0
    Two things: it would seem as if you're only getting 125 watts to each driver which probably isn't enough. When I first tested mine I "accidently" had the sub amp level at about 1/3rd volume and I wasn't very happy either. FULL volume made a huge difference which is 250watts per sub.

    "In the room,..its just not impressive,....upstairs, when its playing,...it seems if the house is going to colapse"

    This could be another clue. By your description I think you're experiencing the effects of truly low bass. You don't necessarily hear it, but stuff is shaking all over. This is VERY different to the 30-40Hz "boom" that a lot of subs put out.

    How does the sub sound when playing music? Try some Metallica for the kick drum or any club/dance music....
     
  8. Brian Bunge

    Brian Bunge Producer

    Joined:
    Sep 11, 2000
    Messages:
    3,716
    Likes Received:
    0
    Trophy Points:
    0
    This confuses me too. Today I delivered a 175L DVC 15 sub tuned to 17.5Hz and powered by the PE 250W amp. The room was approx. 10 x 17 (not as big as yours) and had then entire house shaking. Sure it was on a concrete slab so the floor didn't really shake, but I could feel the bass in my chest and in the heavy leather seats and hear the walls shake.

    I would think dual Tempests in a 15 x 20 room would have to be similar. The only thing I can figure out is that 250W into dual 15" drivers just isn't enough. Also, it's a bad idea to use a plate amp out of a commercial sub. You have no way of knowing what type of boost the manufacturer added to roll off the low end stuff. There's no way a PB12 could be tuned lower than 30Hz or so, so I'd imagine there's boost around 30Hz and then virtually no response below 25Hz or so.

    Brian
     
  9. Kevin Beck

    Kevin Beck Stunt Coordinator

    Joined:
    Jan 4, 2001
    Messages:
    249
    Likes Received:
    0
    Trophy Points:
    0
    Again,..I appreciate all the interst. Its nice to know there are a few people around that will try and help a person. The first impresion I had was the very thing Wayne has mentioned,...tuned so low, its not working with the room. As well as its on concrete. The one guy I know in town that is interested in theater, put his system that he had on his first floor, prety big room, actually, dang big room,.down in a dedicated room in the basement over the winter. I was over there the other day for the fist time since he moved it. Oh it was loud and all, but the bass was gone, compared to what he had before. Not to mention, he had picked up a Velo at who knows how much $$$. The concrete must make one heck of a big difference. I am planning on an Eq., sounds like a must now. Something I hadn't thought about, that Brian has brought up. And I think is a very good point, is the JBL amp,.... It could have all kinds of Eq. added to it in order to make the driver that is in it sound ecceptable in the average family room.
    I just hooked up the smaller sub I built yesterday, and came in here to check postings. Going to give it a test here in a few minutes. Hmmmm,....This is becoming an education,...[​IMG]
    >>>--->
     
  10. Mark Seaton

    Mark Seaton Supporting Actor

    Joined:
    Oct 10, 1999
    Messages:
    599
    Likes Received:
    0
    Trophy Points:
    110
    Real Name:
    Mark Seaton
    Kevin,

    Indeed, get an appropriate amp for the sub. A Hypex HS500 would be my choice for this monster in terms of plate amps, but there are many options in plain old stereo amps as well. I would bet the PB12 certainly has EQ and limiting worked in, and is hurting the response.

    As for designing a sub to a room, you can most certainly do it, just like a car sub is designed. What we find is that the frequencies are much lower, and there are more concerns as to compromises in output. With a quick check, it appears that your sub is rather well matched to the expected boost of your room, and should give very solid response to 15Hz. To drive this point home, we have measured a sub designed with this in mind which was flat to 5Hz in the room. Of course there are variables to consider.
     
  11. Kevin Beck

    Kevin Beck Stunt Coordinator

    Joined:
    Jan 4, 2001
    Messages:
    249
    Likes Received:
    0
    Trophy Points:
    0
    Thanks again guys,..New amp on the way. very curious to do some testing.
    >>>--->
     
  12. Mike Strassburg

    Mike Strassburg Second Unit

    Joined:
    Nov 4, 2001
    Messages:
    421
    Likes Received:
    0
    Trophy Points:
    0
    What amp did you go with?? I'm using the Hypex HS500 and have been VERY happy with it. Fan is dead quiet....
     

Share This Page