Sub signal from SVS not strong enough?

Discussion in 'Archived Threads 2001-2004' started by Sean_B, Sep 27, 2002.

  1. Sean_B

    Sean_B Stunt Coordinator

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    I just got an SVS last week and absolutely love it. I have it set to auto like my previous sub. For some reason, the sub doesn't kick on unless there is a huge amount of bass like from a dvd. If I'm watching television or playing a video game it will shut off even if I'm watching a music channel which should be enough bass for it to kick on. My previous sub would kick on without a hitch so I don't know why the SVS wouldn't. The gain knob is set to 3/4 and my receiver is at -10.
     
  2. Tyler DJW

    Tyler DJW Stunt Coordinator

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    I have the same sort of problem with my receive set to about -6. It's only a problem when I'm listening at low levels. Try increasing the setting on the receiver and reducing the gain on the svs amp. Tom V. recommends reducing the receiver output to reduce distortion (I beleive, sorry to misquote if I'm wrong) but I've also seen this approach recommended with the auto on problem.

    Increasing the receiver level increases the signal to the subwoofer making it more "detectable" and likely to turn on and stay on at lower levels.

    Hope this helps.
     
  3. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    How you combine the level settings on the receiver/processor and the sub is largely a matter of convenience. Just avoid the extremes on either one.

    Try lowering the sub to about 25-33%(on the volume knob) and raising the receiver's output to compensate.

    TV
     
  4. JohnDG

    JohnDG Stunt Coordinator

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    Also, if you are using the receiver's pre-out, use a Y-connector to split the RCA cable into both the L and R inputs on the sub. This increases the strength of the input signal to the sub.

    Don't forget to recalibrate. :)

    jdg
     
  5. John Garcia

    John Garcia Executive Producer

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  6. JohnDG

    JohnDG Stunt Coordinator

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  7. John Garcia

    John Garcia Executive Producer

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    Hmmm... I was not contesting the validity of the recommendation, just wanted some background. I actually have my sub hooked up this way, mainly because the cable I am using has a special adapter for this (essentially nothing more than a very nice "Y"). I had heard this discussion before, and put little faith in it, but never verified or disproved it to myself. My sub does not have auto on signal sensing circuitry, it is controlled only via remote.

    What you say is plausible, and I will do an experiment or two on my system and see what I come up with, just out of curiosity.
     
  8. Sean_B

    Sean_B Stunt Coordinator

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    Well guys, i've turned the receiver sub volue all the way up 0db and my SVS is halfway turned up on the gain dial and still the sub turns itself off when watching television or video game. Halfway up on the sub is about 1/4 over calibrated level.
     
  9. John Garcia

    John Garcia Executive Producer

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    What receiver are we talking about? What are your speaker settings? Is it being used for LFE only, or are you routing bass from the other speakers to the sub also? If you have it set for LFE only, then it will not receive signal if there is no LFE present in the material being played. Also, if you are using a STEREO signal with no bass management (mains set to large), the sub may also be unused depending on your settings, which could be why it goes dormant.
     
  10. Edward J M

    Edward J M Cinematographer

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    Anytime an electric signal is split, the voltage at both ends will be identical. This is a basic electricity principle. Your house electricity works the same way - it is 110V at all outlets.

    Thus, if a Y-splitter is used on the LFE pre-out signal from the receiver, and two cables are connected to the L/R low level inputs on the plate amp, the sub plate amp will see a signal that is twice as strong as it would be if there were just one sub cable.

    Of course, the same exact thing could be accomplished by simply doubling the receiver's sub volume control. The sub plate amp cannot tell the difference, and there is absolutely no "sonic" advantage to using two sub cables.

    If you are experiencing sub "auto-off" symptoms, crank up the receiver's sub volume setting - it's cheaper than adding a second sub cable.

    However, Tom V's advice is sound - avoid extremes on the receiver's sub volume control. If the setting is too low (e.g., -10), the signal to the sub is quite weak, and it will be harder to trigger the auto-on circuity. If the setting is too high (e.g., +10), the tiny LFE pre-out amp may experience signal compression problems and your LFE dynamic range could suffer.

    Finally, John's point is very well taken - if there is no LFE signal present, and this is the only connection to the sub, it will go dormant regardless of how loud the rest of the system is playing on TV/video games. This could be as easy a fix as changing the receiver's default mode of playback on TV/video source material. Many HT receivers default to 2-channel stereo playback for TV/video inputs. Make sure the receiver is playing in the equivalent of "5.1 Circle Surround" mode for TV/video inputs, and it should continue to generate a "pseudo" LFE signal and keep the sub running.

    Regards,

    Ed Mullen
     
  11. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Sean,

    Which receiver are you using?

    Also, be sure you aren't turning up the LFE trim. That isn't the same as the subwoofer leveler.

    Be SURE to recalibrate the subwoofer each time you adjust one of the two gain controls too. If the subwoofe gain knob is "1/4 turn" past proper calibration...you could be 10-15dB too loud now!

    Tom V.
    SVS
     
  12. Sean_B

    Sean_B Stunt Coordinator

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    The receiver I'm using is a Yammy 995. Speakers are all set to small. I leave the LFE at 0. When the sub is calibrated it just doesn't have the punch I'm looking for so I have to turn it up 1/4 more. Calibrated level the sub is almost non-existent. Its good for when listening to music but not for the movies. I like the resonance in the seating area. It doesn't drown out the front sound level by having it this hot.
     
  13. Phil Iturralde

    Phil Iturralde Screenwriter

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    Sean, first of all, … I get all the pant, wall, air, couch moving LFE sub-sonic glorious support playing my Blockbuster DVD Movies and I don’t have to change any setting when I switch modes to hear some impressive solid (electric and upright) bass support / balance punch playing my Jazz Music CD’s.
    I have the Yamaha RX-V995 also, and you have 3 sub controls ...
    1) SW
    2) DD LFE
    3) DTS LFE
    FYI: Read my SVS-25-31PCi HTF review, which includes my Calibration steps with the Yamaha RX-V995.
    Basic summary:
    The key is before you REF Calibrate your DD LFE via Video Essentials (@75 dB – includes a dedicated LFE Test Tone) / or AVIA (@ 85 dB) / or Sound&Vision HT Tune-up DVD (@ 85 dB),
    1) Set the SVS sub Level Control = 12 o'clock high (SVS manual recommendation)
    2) Set the Yamaha SW Control = -15
    3) Play your Music CD @ above listening AVG (I like the peaks to reach 95 dB - RS Meter Dial = 90 dB / Weight = C / Speed = Fast)
    Adjust your Yamaha SW control until it sounds right, where the sound is not too bloated or boomy, while playing your Music CD samples.
    I ended up with:
    SW Control = -11 (room = 20' x 30' w/10' high vaulted ceiling)
    Now REF Calibrate your DD LFE using your Audio DVD Calibration Disc.
    My results using Video Essentials
    1) HT Speakers = 75 dB
    2) SVS 25-31PCi = 81 dB AVG (lowest swing = 79 dB / highest swing = 83 dB)
    3) Yamaha DD LFE Control = -5
    For DTS LFE, just add +10 to the DD LFE result, so ...
    4) Yamaha DTS LFE Control = +5
    Like I wrote above, my Sub / LFE levels is balanced when I switch between my music CD's to DVD's using my Calibration results above.
    Note that your Final REF Calibrated result figures will probably be different due to your electronics and room environment.
    Hope this helps,
    Phil
     
  14. Raine Linton

    Raine Linton Stunt Coordinator

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    About a week ago my audiophile friend suggested that I use a Y to my 20-39pc. He said that all the subs that he tried it boosted the signal about 3db. I thought it wouldn't make a difference since the signal is "summed" but sure enough with the first music cut I played deep bass was present that had not been heard before. I even replayed the cut,removing the left side of the connection and the deep bass was gone. The difference in movies was tremendous, Godzilla and JP...now I know what all the talk is about.
    A recalibration was necessary and I'm so satisfied with the
    house shaking, teeth rattling, butt bouncin bottom that I've got.
     
  15. steve nn

    steve nn Cinematographer

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    I have found out using a Y is very beneficial to. It also helps with the auto on/off. I have herd there are a few subs that this method will not help.
     

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