THX sub vs. non THX sub, pros & cons

Discussion in 'Speakers' started by VincentY, Apr 11, 2003.

  1. VincentY

    VincentY Stunt Coordinator

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    I was told that if I were to use a non-THX sub that whenever I decrease the volume below reference (0 db), which is quite possibly quite often, that the only way to adjust the output of the subwoofer is to use the sub's volume knob on the sub itself, as oppose to using a THX sub, in which case when one lowers the overall volume on the pre/pro or receiver, the THX sub's volume decreases accordingly.

    I am wondering if this is indeed true or is it untrue and based on THX marketing hype?

    i thought that using any sub with a pre/pro/receiver would allow for proper volume adjustment (including adjusting the sub's volume) whenever one were to decrease the master volume on the pre/pro/receiver.

    however, since i was told otherwise, that unless it is a THX sub, adjusting the volume down on the pre/pro/receiver would simply lower the volume of everything EXCEPT the output volume of the subwoofer, so it woun't work properly unless were to be willing/able to reduce the sub's volume appropriately by actually going to the sub itself and adjusting the output volume knob each time one were to go below reference (0 db).

    am i totally confused? don't understand this bass management part for 5.1 systems on THX vs no THX.

    Thanks.
     
  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    There would be a lot of frustrated people on this forum if that were true. [​IMG]

    THX means little to nothing to many people. Even if you use a 5.1 system and use a non-thx subwoofer. As long as you've set it to the right level at calibration (setting the right volume of the 6 channels), the sub will decrease in volume as you turn down the volume on the receiver.

    THX subs had to pass certain standards to earn that certification. Still, you most certainly do not need a THX sub to get good bass. I am certain that there are many subwoofers that surpass THX standards that don't need no stinkin badges to be sold.
     
  3. Cam S

    Cam S Screenwriter

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    THX isn't any sort of bass management, it is simply a "standard" that speakers and amps have met by tests performed in a lab. Personally, and i probably speak for many people here, THX is a load of BS and is just marketing hype. I can't even count how many of the hi end speakers, amps, subs, etc etc, arn't THX certified. Why are these speakers not THX certified, cuz it means nothing.
     
  4. StephenL

    StephenL Second Unit

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    Vincent, you don't need THX to control subwoofer output. Unfortunately there is a lot of ignorance and misinformation about THX. THX standards have improved commercial and home theaters. THX has raised the bar, resulting in better performance of non-THX certified equipment, too. Here are the facts:

    THX home page:
    http://www.thx.com/

    Sound & Vision magazine: THX Certified
    http://www.soundandvisionmag.com/art...&page_number=1

    Sound & Vision magazine: Behind The Numbers: Digital Sound Receivers (includes THX crossover spec)
    http://www.soundandvisionmag.com/art...&page_number=1

    AVS Forum thread: THX certification process
    http://www.avsforum.com/avs-vb/showt...hreadid=122172

    What is THX Home Cinema?
    http://membres.lycos.fr/tessier/thx.htm

    How THX works (theaters)
    http://www.howstuffworks.com/thx.htm

    Lucasfilm THX & Dolby Pro Logic Frequency Response Plots
    http://www.cybertheater.com/Tech_Arc..._pro_freq.html

    Tom Holman interview
    http://www.mel-lambert.com/Writer/In...om_Holman.html
     
  5. Cam S

    Cam S Screenwriter

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  6. Lynn Little

    Lynn Little Stunt Coordinator

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    "I find that hard to believe, as most companies don't give a rats ass about the THX certification."

    I agree. I've got to admit, I might be a little biased. I've owned several brands of amps since 1977. The worst of the bunch were THX certified.
     
  7. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I'd take Lynn amps over THX amps anyday
     
  8. Tony Genovese

    Tony Genovese Supporting Actor

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  9. Brian Bunge

    Brian Bunge Producer

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    There are a couple of specs that a sub or speaker must meet in order to be THX certified. For a speaker or sub to meet the THX standards it must be sealed (acoustic suspension) in design. A THX speaker will have a -3dB down point of 80Hz.

    When you combine this with a THX certified receiver, which will have a 2nd order high pass filter at 80Hz and a 4th order low pass filter at 80Hz. When you combine the receiver with the speakers the natural 2nd order rolloff of the speaker's sealed design at 80Hz along with the 2nd order rolloff of the receiver's 80Hz crossover will give you an effective 4th order rolloff at 80Hz.
     
  10. Dennis Gardner

    Dennis Gardner Stunt Coordinator

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    I have a THX certified 5.1 speaker system made by Altec Lansing for Dell Computers that is great for playing games and listening to music or movies in my bedroom, but wouldn't come close to filling my theater with decent sound. 90 watts for the sub and 22 watts for the satellites
    doesn't bode well for the THX name as signifying that the system is toward the high end of the amp or speaker world.
    I bought it for only $120 new,I didn't expect much.

    I thought that THX was short for George Lucas saying thanks for giving me loads of money, now here's a cool logo to prove you contributed![​IMG] [​IMG]


    DG
     
  11. Tony Genovese

    Tony Genovese Supporting Actor

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    Yeah, the old apples to oranges comparison. I thing we're talking home theater stuff, not PC theater stuff. And from your $120, I'm sure George Lucas got loads of money [​IMG].
     
  12. Geoff L

    Geoff L Screenwriter

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    As you can see the THX thing raises a few peoples blood pressure. I don't know if you could get a clear answer to your question out of all the stuff above but I'll try.

    YES, the THX sub will work fine with any 5.1 receiver and speakers.

    I belive on a THX sub, the back has RCA inputs for THX receivers and a seperate set for non THX receivers,,,,, and allows all the fuction and controls that any other normal powered sub would. Crossover and volume knobs, etc, on the THX sub.

    Someone please correct me if I got the RCA LFE seperate feed inputs on the back of the sub incorrect.......

    ALSO, YES the volume will go up and down with the rest of the system when you turn your receiver up or down.

    Bottom line it (will work just fine)! BUT you might consider a sub that dose not carry the THX logo and get more sub for your money.
    Cause much better subs for your hard earned dollars are out their.

    Nothing wrong with a THX sub, but remember your paying for that (THX Logo) and the THX specs it has to meet.

    "Dollar for THX dollar", a Better sub with TESTED AND REAL WORLD REVIEWED AND MEASURED SPECS & DATA can be had, IMHO.
    Good luck on what ever way you go....
    Geoff
     
  13. Geno

    Geno Supporting Actor

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    Vincent, who gave you that little bit of info about the THX subs? was it a stereo shop? if it was, id love to call them up and mess with thier heads a bit seeing as they like to confuse ppl into buying more expensive items that dont necessarily perform better.........
     
  14. Pierre G

    Pierre G Auditioning

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    Geoff,

    My Jamo THX Ultra 2 sub has 2 RCA inputs, one is Direct and the other is Boundary Gain Compensation, and the same in outputs for another sub. Boundary Gaun Compensation is a THX Ultra 2 requirement for pre/amps, so I guess if the pre/amp doesn't include Boundary Gain Compensation you can connect it to the respective input in the sub.

    I agree with you regarding spending the THX money on a better sub, especially when paying for Ultra 2 products, and I've posted for Vincent about the same subject somewhere else.
     

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