Help with Calibration

Discussion in 'Speakers' started by Bob_Lawrance, Aug 17, 2006.

  1. Bob_Lawrance

    Bob_Lawrance Stunt Coordinator

    Joined:
    Apr 14, 2002
    Messages:
    163
    Likes Received:
    0
    Hey Guys,

    I just got my new SVS PB12-Plus/2 and I am trying to calibrate it with the AVIA disc but I am getting lost on how to do it?

    What does the numbers on the dial on the spl meter mean?
    Which one should I use to calibrate it?
    How do I point the spl at the speakers and sub?

    Any help would be great?

    Thanks in advance.
     
  2. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0
    After setting up your receiver by setting all the speaker sizes to SMALL, entering the speaker distances, etc....

    1) On the SPL meter, set the dial to "80." This will give you a measurement range of 70-90dB, with 74-86dB being the most accurate. For all tests, keep the meter where your head would be - either in front of your face, or slouch down in the seat and hold it up. You'll want to point the meter straight at the ceiling or tilt it slightly forward, for all tests.

    2) Turn your receiver's master volume up to 85, 0, whatever reference level might be.

    3) Go through and adjust the levels of all 5/6/7 speakers so that they all play the test tones at 85dB.

    4) Set the sub/lfe level on the receiver to about 3 to 5 nothces below that of the other speakers. Ie., if all your speakers are at -2, set the sub/lfe level in the receiver to about -5 to -7.

    5) Go into the sub setup menu and play the left channel sub tone. The tone will play a high frequency tone (should still be 85dB), then a bass rumble tone that will be filtered to the subwoofer by your receiver's bass management. At this point, if your speakers are set to LARGE, the sub won't play anything.

    5) Adjust the gain on the subwoofer itself until you are pretty close to 83-85dB on the meter. You will probably notice the reading jumping around a lot. You can lessen this by setting the meter itself to "SLOW" response mode, which will average out the SPL more.

    6) Once you are close with the sub's gain, fine tune the sub's level in the receiver's settings. A readout of 83dB during the bass tones means you are actually at about 85dB. So if you set the sub to 85dB you are already 2dB "hot."

    7) Find the "phase" test tones in the verification section. Mainly worry about the phase for the left/right speakers. Play the tone for the left speaker, note the SPL, then turn the phase on the sub to the opposite end of the knob (0 & 180). One setting will probably give you more SPL. This means that the sub is more in phase with that speaker (playing frequencies at the same time). Test for the right speaker as well. The SvS will have a variable phase, so you can experiment for inbetween settings - ie., 90 degrees may give you the best response.

    8) If you changed the phase setting in step 7, go back to step 6 and re-tweak the levels on the receiver.

    9) Once you have all that down, if you're feeling adventurous you can go into the verification section and run the sweep tones. These will also run through the receiver's bass management according to your settings (crossover, etc.), so sound will come from both that speaker and the sub. The aim is to have the smoothest response with the least amount of dips and peaks, for a good blend between the sub and speaker. You can also spot phase anamolies this way. There is also an LFE channel sweep in this section that plays through the subwoofer only. You can use these sweeps to experiment with subwoofer placement (and even couch placement) and check frequency response at those locations. You may find that moving the sub 6" or a 1' closer to/away from a wall or corner dramatically changes the response. Bass traps will help smooth out the response a bit, and absorb ringing and boominess. For $100 you can also get something called a "Behringer Feedback Destroyer" that will let you EQ the sub's output to make it flat or curved to your desire.


    All of the instructions for what to do with each tone/pattern are on the screen in Avia during those tones. If you haven't watched the intro videos yet, you'll probably want to as a primer on sound and video.


    The SVS website also has calibration instructions in the FAQ, and I imagine your sub has information in the manual as well.
     
  3. Mike Frezon

    Mike Frezon Moderator
    Moderator

    Joined:
    Oct 9, 2001
    Messages:
    40,205
    Likes Received:
    6,660
    Location:
    Rensselaer, NY
    Brian:

    [​IMG] What an excellent post! Thanks!

    I learned some nuances of calibration techniques there that I didn't know before. Maybe I'll re-calibrate my own setup now! (Is there a standard for how often that should be done?)

    That's why I've started lurking in the speaker/subwoofer forum area of late. I've been learning a lot from all the knowledgeable people over here....and polite and helpful in true HTF fashion!
     
  4. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0

    As often as you feel the urge. It's not like CRT RPTVs that go out of alignment and need to be re-checked. If you have kids or wives that might mess with the system, it doesn't take but 5-10 minutes to give Avia a spin and verify levels.
     
  5. Bob_Lawrance

    Bob_Lawrance Stunt Coordinator

    Joined:
    Apr 14, 2002
    Messages:
    163
    Likes Received:
    0
    Thanks Brian

    You mention speaker distance, what is that? What do I do with that?

    If i turn my volume up to 0 that is pretty loud is it not? Is that ok for the speakers and sub?

    I have a HK 520, if that helps
     
  6. Th8ter

    Th8ter Extra

    Joined:
    Aug 10, 2006
    Messages:
    15
    Likes Received:
    0
    Can anyone help out with how to adjust the parametric EQ on the SVS subs?
     
  7. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0


    Speaker distance is the distance from the main listening position to each speaker (or pair of speakers). This determines the delay time. Say DD specifies 10ms delay for rear speakers (I don't know if this is true). If your rear speakers are closer or farther than average, the receiver can adjust the delay time. This is also true for mains and center. Say your mains are 3' closer than your center channel. The receiver can delay the sound of the mains by say 3ms so the sound from the mains and the center channel reach you at the same time.

    There should be instructions in the manual on how to specify speaker distance, or if not, how to calculate the proper delay times.

    And yes, "0" on your HK dial is reference level or very close, depending if you have calibrated reference level to be "0" on the dial. That may or may not be okay for your speakers and sub depending on the speakers and sub, and how they have been calibrated. Ie., depending on your room size, you'd need a truly monster sub/s to do reference level with movies like War of the Worlds. -5 is about where I listen if I can, and -5 to -10 is loud but comfortable for us.
     
  8. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0


    What does it say in the manual for your sub? I assume you would first measure the frequency response, say with a sweep from Avia. Then you adjust the frequency you want to attack, how wide of a range of frequencies you want to attack, and by how much you want to cut/boost. If you have a big peak at 73Hz, then you would experiment with the knobs until you get that peak flattened out.
     
  9. Th8ter

    Th8ter Extra

    Joined:
    Aug 10, 2006
    Messages:
    15
    Likes Received:
    0

    My problem is finding something to do the sweeps with. I have Digitial Video Essentials and Sound & Vision Home Theater Tune Up discs but I can't find anything to do the bass sweeps in them. Does Avia let you do 20, 30 and so on sweeps so you can put your sound level meter on them? Thanks.
     
  10. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0
    Avia has a 200-20Hz sweep for each of the five channels, utilizing your receiver's bass management settings. It also has a LFE-only sweep that goes from 100Hz to 20Hz, and is sent to the subwoofer only. The nice thing about Avia's sweeps are that you can see what frequency you are at on the screen, so you know where to put the filters.
     
  11. Th8ter

    Th8ter Extra

    Joined:
    Aug 10, 2006
    Messages:
    15
    Likes Received:
    0

    Thanks for the tip I will have to get Avia.
     
  12. timZa

    timZa Stunt Coordinator

    Joined:
    Jun 1, 2006
    Messages:
    95
    Likes Received:
    0
    Calibrating the sub the needle moves around. how much db + or - is ok? is a flat response where the needle stays still? the needle im talking about is a RS SPL.
     
  13. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0


    Yes, the needle not moving would be flat response. The less it moves the better.

    You can use Avia's sweep tones (LFE specifically) to experiment with sub placement (maybe even moving your couch a bit) to find the spot that gives you the flattest response.

    Adding bass traps to the corners will improve the response (make it flatter) and soak up a lot of boominess and resonances. Adding an p-eq after that will let you flatten out the response as much as you want.
     
  14. timZa

    timZa Stunt Coordinator

    Joined:
    Jun 1, 2006
    Messages:
    95
    Likes Received:
    0


    Thanks, i did add some homemade bass traps bails of r13 which did improve. where can i get a P- eq? are they easy to use? i am a newbe, so if i gotta go back to college to learn it forget it [​IMG] Im running a pb12+2.
     
  15. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0

    Nice.
    For a parametric eq, the Behringer Feedback Destroyer 1124P is very popular. It only costs about $100 (I got mine from Parts Express, $110 or so delivered). It's a feedback destroyer, but you can use its filters as parametric eq filters.

    The Home Theater Shack website and forums have a great setup guide and plenty of people to help with questions.

    I just got one a few weeks ago, used the guide from Home Theater Shack to set it up, and this is my approximate results before/after:

    [​IMG]

    I say approximate, because I started off by attacking the frequencies using 1/6 octave tones off of my HTPC. Once I got the results seen in the image, I used the LFE sweep on Avia to fine-tune the filters. Now I have (at a specific volume setting) frequency response from my VTF-3 at 79-82dB, with only a couple of spots 1dB above/below this, from 90Hz down to 35Hz. Below 35Hz is the gradual rise down to 17-18Hz, where it falls off drastically.

    Once I got the hang of it, going in and setting and checking filters is a snap. I could probably reset all the filters to +0dB in under 90 seconds, and if I moved to a different room I could re-do the calibration in under an hour (using 1/6 octave tones manually). It would go much faster if I used something like Room EQ Wizard, which does sweeps and readouts virtually instantaneously. That being said, I'm pretty adept when it comes to AV equipment and computers, etc. If you're not, the learning curve will be a bit steeper. But the guide at Home Theater Shack for the BFD walks you through practically everything.
     
  16. timZa

    timZa Stunt Coordinator

    Joined:
    Jun 1, 2006
    Messages:
    95
    Likes Received:
    0


    Brian,

    That looks darn good what an improvement! sounds like the investment of a p-eg is worth it. on last question, how are you able to see what the tones are doing? a program running with your pc i suspect?
     
  17. Brian_cyberbri

    Brian_cyberbri Stunt Coordinator

    Joined:
    Dec 30, 2004
    Messages:
    202
    Likes Received:
    0


    Although you can hook up a meter or a mic to your computer and run special software like Room EQ Wizard, which is much much easier... All I did was put my meter on a camera tripod, positioned it on the couch, ran 1-6th octave tones, and entered the SPL readout in the graph. There are lots of pre-made graphs out there. The one I posted is from an excel file made specifically for BFD use.
     
  18. timZa

    timZa Stunt Coordinator

    Joined:
    Jun 1, 2006
    Messages:
    95
    Likes Received:
    0
    I got the Rives disc today. is my center speaker suppose to play the bass tones? the bass tones come through the center and the sub from 20hz up. also what listening mode is the receiver to be in when testing with Rives.
     

Share This Page