Getting the best out of Dolby Pro Logic

Discussion in 'Archived Threads 2001-2004' started by NathanP, Sep 25, 2001.

  1. NathanP

    NathanP Supporting Actor

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    I accidently listed this is Software, so I'll re-list it here.
    One of my system's uses Dolby Pro Logic,
    My question is,
    How can I get the very best sound from it?
    I want to make it the best it can be, without upgrading speakers of course, which are pretty good themselves..
    I'm using 10 gauge cable too..
    Nathan
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  2. Selden Ball

    Selden Ball Second Unit

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    You might consider improving the bass sounds with a subwoofer.
    Another thing to do is to try to improve the acoustics of the room.
     
  3. Chuck Kent

    Chuck Kent Supporting Actor

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    Balance the speaker-to-speaker and system-to-subwoofer blend by using a sound pressure level meter and test tones. Radio Shack sells a couple of inexpensive spl meters and you can either use the test tones on your equipment or buy a CD that has Pro Logic setup tones on it.
    Also, if you are using a center speaker, make sure it is set to "normal". Very few Pro Logic setups ever had full range center speakers (speakers capable of potent bass down to nearly 20 Hz.)
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  4. NickSo

    NickSo Producer

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    I can never get a good low-end using ProLogic... Any suggestions???
    heres my setup: http://www.multimania.com/sonick182/ht/index.html
    my sub is about 2 feet behind my right speakers...
    its powered using the Amp in the middle (THe goldish components under my TV and DSS Reciever)... I ususally crank it up alot, but then the bass doesnt have enoug oomph... It only plays either sharp jolts of sound (like in a gunshot, punch, or explosion), but it doesnt play any long-winded bass like from the Bass Cello from the title of BAND OF BROTHERS... if i crank it and turn on loudness, it emits this vibration thats really loud, but it sounds really really bad...
    Should I reposition my subwoofer???
    Thanks
     
  5. NathanP

    NathanP Supporting Actor

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    Thanks, Chuck,
    How should I balance everything with spl meters?
    Should everything be the same volume or what?
    Also, I do have a pretty nice sub, but I just can't get the sub I usually get from DD 5.1, is that just me?
    Thanks guys, I look forward to more info from you.
    Nathan
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  6. NathanP

    NathanP Supporting Actor

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    You know what?
    I've been building a new center speaker lately and I'm going to put two mids and a horn in it.
    Thing is, the one I have now has just 2 full range speakers..
    Could that be a big problem right there??
    Nathan
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  7. Chuck Kent

    Chuck Kent Supporting Actor

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    Bass issues are some of the toughest ones to solve. In general, corner placement of a subwoofer gives the most bass. But it can also cause boominess if one isn't careful with the crossover setting (where the sub starts picking up it's share of the system's bass) and the overall volume (in relation to the rest of the speakers.
    One way often recommended to find the best sub location is to set it where you normally sit and you move and listen around the room until you find the best sounding bass. Then place the sub there permanently.
    Why is 5.1 bass better than Pro Logic bass? Well, part of it certainly has to be the fact that 5.1 has a separate, discrete bass channel. And in most 5.1 setups, any speakers set as "small" also send their bass to the sub. All of this tends to make subs work a good bit more than from plain old matrixed 2 channel sources.
    Nathan: How should you set an spl meter? "C" weighting and slow response. Play your test tones on the 70 or 80 dB scale and calibrate all of your speakers to the same volume. This will help to prevent one speaker from drowning out another.
    BTW, Pro Logic (or any 2 channel stereo based matrix decoded surround sound) is highly dependent on a good quality "stereo" signal. If the input signal has poor separation or is mono, you won't get Pro Logic.
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    Almost forgot...
    No Nathan, your 2 fullrange drivers aren't the problem, unless you have the center set as "wide" instead of "normal". The full range drivers you refer to aren't "full range" as in 20Hz to 20kHz. They're full range as in no separate tweeters, woofers or crossovers. The drivers play as "full range" as they can. But this also means no real deeper bass or treble. Mostly the frequencies in between...
    [Edited last by Chuck Kent on September 26, 2001 at 10:38 PM]
     
  8. Chuck Kent

    Chuck Kent Supporting Actor

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    To follow up a bit more...
    Be sure to hold the spl meter vertically at arm's length (microphone up.) Try to hold the mic near where your ears are usually located (and try to not block any of the output from any of your speakers.)
    Pro Logic can be a bit center channel oriented. This is one of the main reasons to balance your setup with the meter. The other reason is that many users often have the surrounds too high in level. The surrounds should not draw too much direct attention to themselves.
    Good luck!
     
  9. NathanP

    NathanP Supporting Actor

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    Thanks guys,
    I just want to reply to Chucks thing,
    My bass is seperated because there is a subwoofer out on my pro-logic processor..
    Is that correct?
    Nathan
    Anyone else?
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  10. Jerome Grate

    Jerome Grate Cinematographer

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    NathanP, if you use the SPL meter, then the sound should be all equal. In other words you'll have to turn up your surrounds to blend in or match your fronts. Now you won't get the bass extension from your surrounds but that's the problem with prologic. What I found out about my old dpl receiver is that it had SRS, which made the surrounds louder and I believe sent the signal in stereo. I never used it because I was already in DD and just didn't care well until Logic 7.
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  11. NathanP

    NathanP Supporting Actor

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    Anyone else have suggestions?
    Anymore will really help..
    Nathan
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  12. Chuck Kent

    Chuck Kent Supporting Actor

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    Nathan: Is this system we are talking about non-Dolby Digital capable? It does make a difference.
    Going on the assumption that it cannot play true 5.1 Dolby Digital (IOW, Pro Logic only), the answer to your question is no, just having a subwoofer connected does not "separate" the bass. There is virtually no bass redirection (bass management) on a Pro Logic only processor.
    A Pro Logic processor's center speaker can be set as Wide, Normal or Phantom.
    Wide sends all mono information (including all bass) to the center speaker.
    Normal sends all mono information above 100 Hz to the center speaker. Center speaker bass below 100 Hz is filtered (the filter is not a brick wall but is somewhat gradual) and sent to the left and right main speakers.
    Phantom means that you have no center at all (or that you want to turn the center speaker off.)
    Rear speakers are not sent any bass below 100 Hz (per Dolby Labs specs.)
    A subwoofer (when used in a Pro Logic ONLY system) typically receives ALL bass in the program. But none of it is removed from any other speaker and only reproduced from the sub. Many Pro Logic only setups had a subwoofer output that sent all system bass from 180 Hz (or so) and down to the sub.
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  13. Inspector Hammer!

    Inspector Hammer! Executive Producer

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    To get a more accurate reading from the meter, mount it on a camera tri-pod, this will keep the meter perfectly still, and allow you to stand away from the area so you won't block any of the speakers.
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  14. NathanP

    NathanP Supporting Actor

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    Yah, this sysem is not DD 5.1 compatible..
    Thanks,
    Nathan
     
  15. NathanP

    NathanP Supporting Actor

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    So anyone else have anything to say?
    I'm just looking to get the best experiance out of my Dolby Pro Logic..
    Nathan
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  16. NathanP

    NathanP Supporting Actor

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    Is that it?
     
  17. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    I can play a DVD in Prologic 2 mode and get pretty decent bass (compared to DD 5.1). But I get very little bass from VHS tapes. The best example I can cite is Jurassic Park on VHS. I have to crank the subwoofer up 10dB above my normal level to hear theater-like bass.
    I believe that the problem lies in the capabilities of VHS recording and/or the performance of my particular VCR. If you're using a VCR, you probably have the same problem. If its a DVD player you still might try borrowing DVD players from friends/family and comparing their performance.
    Now I don't even have my analog outputs from the DVD player connected to the receiver. So even when I'm playing DVD's in Prologic 2 mode, they still see the benefit of the digital connection. I don't know what kind of performance difference that makes.
    This is just a shot in the dark, but maybe it'll help.
     
  18. NathanP

    NathanP Supporting Actor

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    Thanks, man.
    I just haven't had many good experiances with subwoofers with DPL.
    Hopefully, it'll all be fixed when I get my new sub in..
    Nathan
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  19. Matt Wallace

    Matt Wallace Second Unit

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    Nathan,
    What part of the DPL experience are you trying to enhance? I think you've been given some great advice on subwoofer issues, but you don't seem satisfied. That would lead me to think that you have other areas of DPL performance that need to be addressed that you aren't mentioning. Surround envelopment? Seperation of channels? Dialogue clarity? What are you looking for, exactly? Also, stating your equipment may help to recommend things/tips.
    Matt
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