Powered towers + external sub, THE way to go?

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

  1. Bob_A

    Bob_A Supporting Actor

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    One of the "experts" at AR (Terrence) has posted the following information:

    Power towers in and of themselves are not bad. The way Rob COULD use his would make him better off than most. Where power towers have problems is in the LFE. Because they are spaced, and the LFE is reproduced by both speakers, it is subject to cancellations at some frequencies. Its response will definately be rougher than a sub in a corner. However, If you were to use a sub for the LFE, and set you front towers(and only the front)to large, and your center to large(Rob can do all of this) you have the potential for a closer alignment to a movie theater setup. Spatially and timbrally, this is ideal because you do not move bass between 40-80hz that is eq'd for the center of the room, to near the walls. Anytime you do not have to redirect bass, that is a good thing. Especially considering all the processing that bass management requires.

    Cancellation comes from having more than one source producing the SAME information. Like what would be found if one used two space subs to reproduce the LFE. This can also be found in two channel setups were the vocals, and bass is reproduced by the two speakers. With three front channels reproducing bass within their OWN channels, cancellations cannot occur. One speaker is playing the bass from that ONE channel. Rarely, and I mean rarely will you find bass coming from all the front channels simultaneously, same amplitude, same frequencies. Engineers do not need to do that anymore. We now have the LFE channel if we want the bass to smack you in the chest. With prologic, if you wanted big bass, you had to put it in all three screen channels simultaneously.

    Movie theaters don't use bass management. Whatever the frequency response of the speakers is, thats what comes out of them. Having a sub on the LFE, your front L,C,R, on large, and the surrounds on small, mimicks the alignment of the movie theaters speaker system. There is no fear of cancellations because each speaker handles the output unique, and exclusive to that channel. So there is no real acoustical interaction that would produce cancellations.

    Setting the speakers to large, with a sub(s) handling the LFE will not create cancellations. Since the LFE is always 10db's higher than the center channel(or any one channel for that matter), it is unlikely to setup the conditions for cancellations. Remember, cancellation can only occur when identical phase, amplitude, and frequency of a signal is reproduced by multiple sources. The LFE at 10db's higher than the mains will not allow for that condition to exist. Each front speaker playing its OWN bass will not allow for that condition to exist.
     
  2. Bob_A

    Bob_A Supporting Actor

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    Edit: The title should read "Powered towers (and other near full range speakers) + external sub, THE way to go?
     
  3. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Basic problems with the premise...

    1) the freq response is going to suffer(usually severely)regardless of what any other speaker is doing.

    2) on many bassy scenes...the main L/R channels do indeed have nearly identical bass in both amptitude and frequency.(I think this might be due to the downmixing capability the Decoders have to offer). I think I'm going on 3000 bassy scenes measured now...so I do consider myself somewhat versed in the art.

    TV
     
  4. Bob_A

    Bob_A Supporting Actor

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    Sure, you can find faults with any setup.
    "on many bassy scenes...the main L/R channels do indeed have nearly identical bass in both amptitude and frequency."
    Nearly identical bass, correct? So you are saying that his statements of "Rarely, and I mean rarely will you find bass coming from all the front channels simultaneously, same amplitude, same frequencies" and "There is no fear of cancellations because each speaker handles the output unique, and exclusive to that channel. So there is no real acoustical interaction that would produce cancellations" are wrong?
    Now, do you disagree with the following statements:
    If you were to use a sub for the LFE, and set you front towers(and only the front)to large, and your center to large(Rob can do all of this) you have the potential for a closer alignment to a movie theater setup.
    Spatially and timbrally, this is ideal because you do not move bass between 40-80hz that is eq'd for the center of the room, to near the walls
    Anytime you do not have to redirect bass, that is a good thing. Especially considering all the processing that bass management requires.
     
  5. Lewis Besze

    Lewis Besze Producer

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    MY stereo[main LR speakers],have cancellation on my room,in the critical, 50-80hz,when set to large!With the 2 sub the curve gets even more "funkier".

    When I set them to small+subs everything evens out,so no, your "favourite scenario" don't work for me.

    BTW the so called movie theater sound is far inferior to what get home,so if that's your goal then you cut yourself short IMO Bob!

    BTW is there any other topic that interest you in this hobby Bob?
     
  6. Steve_Ma

    Steve_Ma Second Unit

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    Post deleted. This looks too farmiliar.

    --Steve
     
  7. John Kotches

    John Kotches Cinematographer

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    Bob,

    Movie theaters use dedicated subwoofers for each front channel (yes that means 5 for SDDS).

    Movie theaters have to fill a much larger acoustic space. This space is much greater than an order of magnitude than almost every home theater space. I don't want to say literally every home theater space, because I'm sure there's someone out there that has a "full sized" movie theater for their home theater.

    Then again, this person wouldn't be trying to justify their purchase ad infinitum.

    Regards,
     
  8. Steve_Ma

    Steve_Ma Second Unit

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  9. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Well I disagree with those statements, Bob.

     
  10. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    >>>Sure, you can find faults with any setup.>Nearly identical bass, correct? So you are saying that his statements of "Rarely, and I mean rarely will you find bass coming from all the front channels simultaneously, same amplitude, same frequencies" and "There is no fear of cancellations because each speaker handles the output unique, and exclusive to that channel. So there is no real acoustical interaction that would produce cancellations" are wrong?>Now, do you disagree with the following statements:
    If you were to use a sub for the LFE, and set you front towers(and only the front)to large, and your center to large(Rob can do all of this) you have the potential for a closer alignment to a movie theater setup.
     
  11. Bob_A

    Bob_A Supporting Actor

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    Remember that these are not my words, this is what Terrence has claimed.

    Lewis, some of the newer movie theaters actually sound awesome, although you still don't generally get as much shake as in a good home setup.

    Ryan, Maybe you can discuss this with Terrence at AR!

    "I suppose that would be closer to the *alignment*(if the word alignment simply means the crossover points used as is implied) of many commercial theaters."

    Great.

    "Unfortunately, this isn't something a HOME theater should strive for."

    Some people might feel that [email protected] from corner-loaded external subs would be something that a home theater should not strive for.

    "I would MUCH rather have the bass produced from a point source that can reproduce the signal cleanly,and has a smoother(more accurate)response signature at my ket theater seating."

    I don't think that Terrence would recommend such a setup for everyone, but he claims that there is potential for such a setup if the front three channels are capable (flat down to 30-40Hz?).

    "Yeah, I guess MK,THX,Dolby labs,ect,ect have no idea how to properly *process* bass being rerouted for bass management now...?"

    I never saw Terrence make such a claim.

    "Bob...it's almost amusing that you'll poo-poo names like Nousaine,Keele,Toole,Holman,ect,ect because the decades of research they have done in the field of low frequency acoustics haven't concluded with data that parallels your current belief system"

    What exactly would you say is my "belief system"? Remember, this is Terrence who has made these statements. If you want to discuss with him at AR to find out how much he knows about audio, then go ahead. What amuses me is how you (among others) are always so quick to put down any powered tower (or any other near full range speaker), even though it is clear that some people have much preferred powered towers (and other near full range speakers) + external sub.

    Keep in mind that I am not trying to make any definitive conclusions. But does anyone here have powered towers (or capable near full range speakers) across the front in addition to an external sub, who has actually compared the proposed setup to one where everything was set to "small"?
     
  12. Mark KU

    Mark KU Stunt Coordinator

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    Please, stop feeding the troll.
     
  13. Brian Bunge

    Brian Bunge Producer

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    Bob,

    So if this is not your opinion then what was the point of posting Terrence's comments in the first place? Either you're using it as some sort of defense as to your own opinion on the subject or you are just "picking a fight". Or maybe both.

    In any event, what would be the point of anyone here discussing this with Terrence? Terrence didn't post the information on HTF. You did! As such, you should be the one to defend it!

    Here's an example: You go up to TV and say "Brian said you're ugly and your mother dresses you funny!" TV gets pissed and beats the hell outta you. You start whining and say, "But this isn't my opinion! Brian said it! Take it up with him!"

    Unless you share the same opinion, what is the purpose of telling TV this?

    Brian
     
  14. David Giles

    David Giles Stunt Coordinator

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  15. Bob_A

    Bob_A Supporting Actor

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    "So if this is not your opinion then what was the point of posting Terrence's comments in the first place?"

    To me there seems to be some potential to his comments. Maybe you disagree, that is fine. If you go to AR, you will quickly see that Terrence knows a lot about audio. Trust me, he has heard many "quality" setups (including HSU and SVS). Obviously Terrence does not regularly (if at all) post over here. Clearly there must be a reason why Terrence would recommend such a setup for some people. As I said before, Terrence can explain it much better than I can. For clarification, go visit AR. As for your "example", that really doesn't make sense to me. You give a person a message which was said by someone else, and this person decides to take it out on you?
     
  16. Russell _T

    Russell _T Supporting Actor

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    First of all, Bob's not a troller, he's just maybe a teeny tiny bit misguided. Now that he's brought in reinforcements we can rename it "The Bob and Terrence Show". And it's the longest running show in town.

    Russ
     
  17. Stacy Huff

    Stacy Huff Second Unit

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    Ok, I'll play.
    Now remember, these aren't my opinions, they belong to other people. I found the post by Brian Florian on bass management to be particularly enlightening, although there is quite a bit of great information all through the thread. Check it out. If you disagree, take it up with Brian or whoever.
    http://www.avsforum.com/avs-vb/showt...ight=Sub+Music
     
  18. Bob_A

    Bob_A Supporting Actor

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    Russell, why would you say that I am "misguided"? I am not the one who is so quick to instantly rule out one particular scenario, even though user input shows that this scenario may be preferrable in some cases.
     
  19. Bob_A

    Bob_A Supporting Actor

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    Stacy, that's great. Now, would it make sense for me to question or attack you? Of course not. Regarding an audio setup, there is no "right" way to do it for everyone. Just my opinion though.
     
  20. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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