5db difference between avia and internal test tones, why?

Discussion in 'Archived Threads 2001-2004' started by John Tompkins, Mar 25, 2002.

  1. John Tompkins

    John Tompkins Supporting Actor

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    I have the lex mc-1 and calibrated the side speakers using internal tones on the lex. I then calibrated using avia and the sides were 5db lower using avia versues using the lexs internal tones ?

    I turned off the BACK speakers to use avia as you cant calibrate the BACK speakers but only the side speakers. The funny thing is, when I turned the BACK two speakers on and ran the avia test tones on the sides, the calibration was the exact same as the lexs internal test tones. Keep in mind though, doing it this way avia playes tones from both the side and the back speakers at the same time, be it the left or right. Does the lex maybe take this into consideration and lower the sides internal tones by 5 db ? PLEASE HELP...thanks
     
  2. John Garcia

    John Garcia Executive Producer

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    Do a search, this was covered in depth recently. (may have to look in the speakers forum)
    *edit - I found it:
    This post will probably have the info you are looking for.
     
  3. John Tompkins

    John Tompkins Supporting Actor

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    John Garcia,

    This isnt my problem(75db, 85 db confusion). The avia tones on the front speakers l/r/c are 85 db and on the lex I calibrate the fronts to 85 db as well. The thing is the sides are 5db lower on avia then the lexs internal tones. In other words I calibrate to 85db using lexs internal tones and then use avia at whatever volume position (master volume on lex) required to make it 85. The front speakers l/r/c read 85 db on avia but for some reason the backs are 5 db to low, as they read 80 db instead of 85 db like the fronts ?? I know this is strange but there has to be an explanation
     
  4. Jeremy Hegna

    Jeremy Hegna Supporting Actor

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    John,

    There is about a 2-3db difference between the internal test tones of my Denon 5800 and Video Essentials.

    There has been debates on the difference of using a "pro" calibration DVD like "AVIA" or "Video Essentials" vs. those internal test tones we all have. Using the internal test tones, you are calibrating your receiver generically. Using the test tones of Avia or VE, you are calibrating your receiver/pre-pro to the output of your source (DVD, CD, etc.) This may be where some of the difference lies. I used to only calibrate my stuff with internal test tones til I purchased VE and the difference was evident.

    Jeremy
     
  5. Greg_R

    Greg_R Screenwriter

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    Could it be possible that your Lexicon allows different calibration settings for each input (with the internal tones setting a baseline for all of them)? Another possibility is that there is some form of processing going on with the rear channels (logic 7, etc.). Make sure you're using the vanilla DD setting while using the Avia disc. If this doesn't work, you should try the Lexicon forum on the SMR forums site...
     
  6. John Garcia

    John Garcia Executive Producer

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    This has to be in reference to the source then, because my internal tones on my receiver gave me basically the same readings as the S&V disc. VE was right about 10db lower.

    That would make sense because it is the same as calibrating color/contrast/brightness on your monitor with VE, Avia or S&V would give you great results for THAT DEVICE and it's particular type of connection. That does not mean these settings will work for other sources...however in John Tompkins case, that does not sound like what is happening.

    Another thing is, you could measure your levels again, and get different readings based on how and where you hold the meter.

    The real question is: Does it sound good to you?
     
  7. John Tompkins

    John Tompkins Supporting Actor

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    It could be that I had the mode set to logic 7 on the lex when I calibrated using avia, Greg may be on to something. I will recalibrate tonight making sure I put the lex in straight dolby digital mode.

    5db is ALOT of difference on the sides, thats why I dont think there should be that much of a difference between avia and lex because again the front l/r/c on dead nuts on with avia-lex tones.

    John Garcia, I listened to some movies using the 5 db higher sides(avia) and really liked it, but it could be that I like it incorrectly jacked up in the back soundfield. I guess there is no right/wrong but I would like to know what is correct before I start altering the volumes to my liking.

    Does anybody else jack up their sides/rears higher then they should be ??
     
  8. John Kotches

    John Kotches Cinematographer

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    John Tompkins,

    1) Internal test tones should be calibrated to 75dB SPL -- not 85dB SPL, with all speakers being level.

    2) AVIA calibrates to 85dB, when volume is set to 0.0dB.

    That still doesn't answer your question.. why are they different?

    The test tones in the receiver are fixed levels stored in a ROM. AVIA uses the entire decoding chain, DD decoder, DACs etc.

    Regards,
     
  9. John Tompkins

    John Tompkins Supporting Actor

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    John Kotches, I realize about the 85 db setting on avia, but like you said that doesn't answer why after calibrated the sides are 5 db different then the front l/r/c.

    Your right about the dacs/decoding etc through avia and not internal tones of the lex but again you would think that the fronts and sides would all raise or lower at the same volume and not be 5 db different from fronts too sides.
     
  10. John Tompkins

    John Tompkins Supporting Actor

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    Well, I figured it out (sorta). I turned off logic 7 and used straight DD using avia test tones. The sides are no longer 5 db higher then l/r/c but they are now just 2 db different then the fronts. Still odd but much closer this way..
     
  11. Steve Morgan

    Steve Morgan Second Unit

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    John,

    There is an indepth discussion on SMR home theater site about this in the Lex section.The powers that be say to use internal test tones on the Lex. It is THX calibrated.They also compare to optimode and VE.audio Buys is sending me the V4.After 10 days with the MC1 I can say it was a good decision to sell the Ref 30!I overlooked instructions calibrating the first week and did not turn the sub crossover to off.I did today and it made a huge difference in blending bass from the subs to the fronts.I also have trip[ole sides and had them in dipole but switched them to standard and the back soundstage really engulfed me.AC-3 2.0 is so close to DD 5.1 I have to check the osd at times to see what happening.They say the V4 brings performance up a notch so I am excited.I finally am enjoying the suround experience and feel I am not missing anything.Up until now I always felt I should be in a vacum of sound with my 7.1 set-up and something was missing. Not any more!I am waiting on the V$ chip to do some serious tweaking but I have found that 80hz crossover for Fronts and sides and 120hz for center gives me the best sound so far, even though the Center is capable of bass to 35hz.Lexicon sure knows what they are doing.A pre/pro 3 years old sounding as good or better than units coming out right now.Ricky T, I owe you dinner! Now we have to bombard Lexicon and persuade them to think about upgrades for the MC1 even though they said they are not going to.

    Steve M.
     
  12. John Tompkins

    John Tompkins Supporting Actor

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    Steve,

    Gald to hear it and I'm not at all surprised. You will find that you can tweak it in further and further. Try the tilt, re-eq on/off, voice enhance and bass enhance. They all work incredible well. You can change the sound to whatever your likings are!

    There hasnt been enough time in the day since I receieved the lex, a tweakers dream.

    When did they ship the version 4.0 chip, when are you supposed to recieve it ? hopefully audiobuys will be quick about it.
     

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