The real deal on bipoles

Discussion in 'Archived Threads 2001-2004' started by Travis G, Feb 27, 2002.

  1. Travis G

    Travis G Stunt Coordinator

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    I am not talking about dipoles. I am talking about bipoles like Definitive Tech's and Blose (all drivers radiating accoustically in phase). Is there really an advantage or is it just a gimmick.
    I don't believe this would sound good at all. I think it would just reduce the critical distance to almost nothing. I know there are more of you with an opinion on this so lets hear it.
    Travis[​IMG]
     
  2. John Doran

    John Doran Screenwriter

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    the soundstage is given more depth and width, but at the cost of detail and resolution in the stereo imaging; the sound-energy reflected off the front-surface of the room can make it difficult to generate the same sort of focus within the soundstage that you can get with some direct-radiating speakers.
    but, in the end, you have to listen and make up your own mind about which sound you actually prefer. i have bipoles as my mains, and i love them.
     
  3. Larry B

    Larry B Screenwriter

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    Travis:

    John hit the nail on the head when he stated

     
  4. Sean M

    Sean M Stunt Coordinator

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    I just picked up a set of Mirage OM-9's to replace my direct radiating fronts and there is certainly a difference in the way they sound. I actually prefer the Omnipolar (bipolars in a shallow cabinet) sound of these speakers. They sound a lot less like...well speakers. Pretty much all of the best speakers I've ever heard were multi-polar (bi-, di-, or Omnipolar). I think I would say that the imaging is not as precise in its location of objects left to right. I hear all of the same things, they just aren't as clearly delineated in space. Oddly, the last time I was in a place that had live Jazz (can't remember the name of the club), it sounded more like my Mirage speakers than my direct radiators.
     
  5. Bob McElfresh

    Bob McElfresh Producer

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    There is a psycho-acoustic effect called the "Hass Effect". It was a study of how people perceive echos.
    What they found was that if a person hears a sound, then an echo, they perceive it differently depending upon the delay between the sound and the echo:
    1-5 miliSeconds: both sounds are perceived as the same
    6-12 miliSeconds: Some confusion, some people detected only 1 distorted sound
    12-20 miliSeconds: People heard 1 sound, but they perceived that the sound source was now several feet farther away.
    A bipolar speaker setup 3-4 feet from a rear reflecting surface can fool you into feeling like you are in a much larger space.
    A few years ago, we pulled everything out of our living room to have wallpaper removed/painting/etc. I managed to sneak the TV & HT equipment back in as the only items in the room for a day or two. The sound was different, but it was dramatic when I watched the movie U.S. Marshals. There are a few scenes that bounce between a small, stuffy office and the outdoors (cell phone/phone booth). When the scene would shift, the change in the sound felt like the pressure change in an airplane. I thought my ears were going to pop from the walls of the room suddenly moving in or out. It was almost unpleasant (but very cool) [​IMG]
    When I got my bipolar towers, I immediatly loved them for giving me a "theater like" sound. But I hated/did not like them for music.
    Here is the trick: I love movies so I am very comfortable/familar with a large theater room. The bipolars helped give me this. But most of my music listening is with headphones so the spaciousness given to my favorite CD's sounded ... different/funny.
    Then I read posts here about how bipolar speakers sound great for music to some people??? My guess is, these people attend a lot of concerts so getting the large-room/amptheater sound sounded good to them.
    My advice: If you like movie-theater sound, or have attended lots of live performances AND (very critical AND) can pull the speakers 2-3 feet into the room - consider a set of bipolar speakers.
    Another note: as people strive for music accuracy/detail, they often turn to large panel speakers. These are technically dipolar speakers (because the forward/back sound are out of phase), but they are positioned/used like bipolars: several feet into the room to allow a back-echo delay.
     
  6. Bob_A

    Bob_A Supporting Actor

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    "Then I read posts here about how bipolar speakers sound great for music to some people??? My guess is, these people attend a lot of concerts so getting the large-room/amptheater sound sounded good to them."

    Bob, I'm not sure about that. I have been to only a few large scale concerts, and I enjoy the direct radiating sound, but I still love my bipolars with music. In order to get great music out of a bipolar speaker, you need to pay close attention to setup and associated equipment. By the way, how have you wired your speakers? Have you tried running them "large", with your external sub used for LFE only? Thanks.
     
  7. Travis G

    Travis G Stunt Coordinator

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    Interesting, so it increases the depth of the sound stage. But why not use dipolar speakers? Wouldn't they have the same advantages withouth the drawbacks? True, dipoles require equalization to have good extention but it seems like aiming half the sound at the wall would reek havock on the T60 and critical distance. Is this the case or not? Maybe the critical distance is not so critical for home theater?

    Bob, I would be interested in reading about this study. Can you give me a reference?

    Thank you

    Travis
     
  8. Craig_Kg

    Craig_Kg Supporting Actor

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    So are Bose correct??? [​IMG]
     
  9. Bob McElfresh

    Bob McElfresh Producer

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    Travis: The traditional "Dipole" rear speaker for HT is a INDIRECT radiator. It fires along a wall with none of the drivers facing the listeners. This makes the reflective properties of your walls a major part of the sound you hear. The goal is to only put Ambiant/non-directional sounds to the rear speakers in a ProLogic system and the indirect sound will help hide the speaker source.

    But reflecting off the walls is really going to degrade the sound.

    You might do a internet search on "Hass Effect" or "Psycho Acoustics". Another good article is issue #15 of WideScreen Review. Although written in 1995, it has a lot of good information on the Dolby Digital speaker system and time delays/distance/room effects. You have to order the back-issue, but it's well worth the $18.

    Bob: I think I'm set to small right now for the towers to let the SVS take the low-frequency duty. Been too busy to even watch a lot of movies, let alone have a "play with the electronics" day. (sigh)
     
  10. Travis G

    Travis G Stunt Coordinator

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    Craig,
    I have said this many times and I still belive it's true. Reflecting most of the sound off the walls is performing surgery on the original program. But, perhaps reflecting half of it off the walls is arguable and reflecting most of it (like the Bose 901s) is total crap.
    Bob,
    I'm actually reffering to dipoles such as electrostatics, magneplanars, and Dr. Siegfried Linkwitz' dynamic dipoles.
    The reason I ask is because according to Dr. Linkwitz dipoles actually reduce the T60.
    Travis
     

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