subwoofer calibration

Discussion in 'Archived Threads 2001-2004' started by EricHaas, Mar 23, 2002.

  1. EricHaas

    EricHaas Supporting Actor

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    Hi, I have a question about subwoofer calibration. This is a spinoff from another thread.

    I have attempted to calibrate my system using Avia and the Rat Shack analog SPL meter. I had to turn my sub amp to about 1/2 maximum so that I could properly level match (all speakers are set to small). The test tones produce a relatively steady meter reading (response=slow) with the other speakers. But with the subwoofer, the needle jumps around during the test tone, because the sub test tone is an uneven rumble rather than even pink noise. Given that it jumps around so much, how do I determine if I have a level match? Do I try to guestimate the middle of the range that it is jumping around in? Or do I choose the high or low end of the range?
     
  2. Vince Maskeeper

    Vince Maskeeper Producer

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  3. EricHaas

    EricHaas Supporting Actor

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    Sorry, it hadn't occured to me that this specific question had been asked. I will run searches on calibration questions in the future.
     
  4. Vince Maskeeper

    Vince Maskeeper Producer

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    Cool,

    And if you cannot find an answer- feel free to post.

    However- you'll find that nearly every standard calibration question is asked in the "basics" area once every 15 days. Most of the issues you will encounter, you will find, are amazingly common.

    Try a search on calibration or AVIA, and you will find answer to questions you haven't even encountered yet.

    -V
     
  5. EricHaas

    EricHaas Supporting Actor

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    Thanks. Good advice. I see this for example:
    http://www.hometheaterforum.com/htfo...threadid=58241
    Someone in this thread has the same sub as me (Sony SA-wm40) and he said he has to set it to half volume on the amp, and -4 to calibrate. I had to set it to half and -3, so at least I know there isn't anything wrong.
    The only thing that still bothers me is that there is a *14* db variation between the subwoofer level with the Avia tone and Denon 3801's test tone. I know that there are supposed to be differences between the Avia tones and receiver tones (yes, I ran searches), and that the Avia tones are considered more reliable. But a *14* db variation? You can hardly hear the sub test tone on the receiver, but under identical master volume, levels, speaker settings, and amp settings, it booms and rumbles with the Avia tone. Difference is -8 on the meter vs. +6. All the other tones for the main speakers are within +/- 1 db between Avia and the Denon. Very odd.
     
  6. Vince Maskeeper

    Vince Maskeeper Producer

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    Sounds like the LFE is not being boosted properly. The avia tone is a rerouted tone from the left channel, while the receiver tone is likely LFE specific.

    LFE needs a 10db boost to be even with rerouted bass. This boost is controlled by the position of the LFE control. The Denon has one, it is somewhere in the menu (I have one as well)-- check the manual (if you can't find it, let me know and I'll find the page number for you).

    As I mentioned in the other threads I linked you to, the LFE pad setting should be as high as it goes.

    -Vince

    PS: Also, I'd suggest putting bass set to SUB only (not both) for Avia setup.
     
  7. EricHaas

    EricHaas Supporting Actor

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    Yeah, actually I checked that before my last post (should have mentioned it.) It's on page 52 of the 3801 manual, and is accessed with the Surround parameters button on the remote. It is at 0 where it is supposed to be.
    And yes, bass is sub only.
    I can verify that the Denon test tones are not measuring LFE only. Setting the speakers to large causes a dramatic decrease in output in the sub test tone, where it shouldn't matter if it were LFE only.
    I don't know, I guess I'll try to live with it this way on the theory that I am used to it running too hot. But the sub sounds totally anemic. [​IMG]
     
  8. Vince Maskeeper

    Vince Maskeeper Producer

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  9. EricHaas

    EricHaas Supporting Actor

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    Yep, that's what I think. I may just have to calibrate the sub by ear if over time I find that I am unsatisfied. I do think the Denon is part of the problem. I find it's interface, remote, manual and menus to be non-intuitive. You shouldn't have to hunt for things like LFE level. I presume the problem lies somewhere in a setting, but I'd rather calibrate by ear than spend hours more trying to figure out what it is. Thanks for the help.
     
  10. Vince Maskeeper

    Vince Maskeeper Producer

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    Eric,

    Good luck.

    I do want to stress one point however: From what you've said you have a serious issue which might prevent you from finding a decent sub level: there seems to be a big variation in the level of bass from the dedicated LFE versus bass coming from rerouted main signal. While you can attempt to "calibrate by ear" I think this core problem will haunt you greatly as you attempt.

    Because there are effectively 2 types of bass heading to your sub (rerouted mains bass and dedicated LFE signal)-- and they are at such odds with one another in terms of level- any attempt to "calibrate" will be a compromise between the two.

    This means that likely you will arrive at a point where discs with large amounts of bass on the main channels will seem excessive to you and discs with a large amount of their bass in the LFE will seem anemic.

    Again- it sounds like you have at least a 10db difference between LFE signal and rerouted bass- and this will have a very large impact on any and all DVD discs you play on that system. Any disc which relies heavily on the LFE track for its bass material will probably be really lacking on your system.

    I would really strive to find the problme in this case, as I don't think it will be possible to find a consistantly pleasing level given the nature of the problem. My first step would be to track down a copy of VIDEO ESSENTIALS which has a real dedicated LFE signal in order to figure out if the problem is due to an errored tone in the DENON, or due to a real 10db difference in LFE level vs. rerouted bass level.

    Good luck.

    -Vince
     
  11. EricHaas

    EricHaas Supporting Actor

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    Thanks man. That's a good suggestion. Another thing to ponder here. I now notice that when I toggle the main speaker setting between large and small, it makes NO difference in the levels I am getting on the SPL with *either* Avia *or* the Denon tone. Yet I could swear just recently I observed it made a huge difference. I have played with every setting I can find, and I keep getting thundrous bass with the Avia tones and virtually nothing with the receiver tones. I can't just assume that the receiver isn't implementing my "small" speaker designation, because it appears to be doing so just fine with the Avia tones. I suppose something is reducing the LFE level, but it isn't the setting that's doing it. Could it be something on the sub itself, or some other setting of the receiver? I'm just thinking out loud here.
     
  12. Boris

    Boris Extra

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    Hi.

    I too have a Denon 3801.

    My system is calibrated using Avia, all speakers set to small, LFE toggle/pad in it's highest position (0dB), 85dB measured all round.

    I never even bothered with the receivers internal test tones. One day while tweaking I thought I'd give them a try, just to see how accurate they were compared to Avia. Well, the main channels were basically the same but the LFE was measuring 10dB down!!???

    I also checked my system using the THX optimode test with its discrete LFE tone and that concurred with Avia.

    I ignored the Denons tones and stayed with the Avia settings.

    That was while ago so I will double check again tonight in case I'm mistaken.

    Cheers

    Boris
     
  13. Boris

    Boris Extra

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    Hi.
    Confirmed last night. My Denon 3801s LFE tone is 10dB down.
    My LFE control pad is in the correct position (0dB, highest).
    So if I used my receivers internal test tones to calibrate, my LFE would be at least 10dB hot.
    I'll stick with Avia [​IMG]
    Hope this sheds some light on your discrepancy Eric.
    Cheers
    Boris
     
  14. EricHaas

    EricHaas Supporting Actor

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    Boris:

    Thank you so much for posting. Now I have confirmation from two others. Someone over at another forum said the sub tone for the 3801 was 8 db hot compared to Avia for him. Because I haven't had like 25 people pipe up and say they experienced this, I have a sneaking suspicion that it may be particular to the 3801 (not the 3802). In any event, it sounds like a glitch with the 3801 sub tone. Because I had calibrated it by ear using the 3801 tones prior to getting Avia and the sub always seemed thundrous and overpowering to me. I thought it was the fault of the sub which has a reptuation for boominess. Now I guess I am going to have to adjust to more accurate base. I think this really reinforces what I have heard before, which is never trust a receiver's built in test tones. You've got to get something like Avia or VE.
     
  15. Boris

    Boris Extra

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    No problem Eric.

    I've always wondered if all 3801s are like this.

    If so I bet there are some way off LFE calibrations out there.

    So 10dB over + maybe a personal 3-5dB boost, wow. Can't sound good.

    Yeah, stick with Avia or VE.

    Cheers

    Boris
     

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