Is this a good Bass calibration CD

Discussion in 'Archived Threads 2001-2004' started by Craig Ball, Jul 24, 2001.

  1. Craig Ball

    Craig Ball Second Unit

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    I found this link that has three test cd's, I'd like to know if one of these would be good to set up my Dual 20-39CS, ART-351 coming soon maybe.
    http://store.stryke.com/
    Click enter then TEST CD.
    Thanks
    Craig
    [Edited last by Craig Ball on July 24, 2001 at 02:31 PM]
    [Edited last by Craig Ball on July 24, 2001 at 04:29 PM]
     
  2. Craig Ball

    Craig Ball Second Unit

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    ANYBODY? [​IMG]
     
  3. Craig Ball

    Craig Ball Second Unit

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    ANYBODY?
     
  4. Deane Johnson

    Deane Johnson Supporting Actor

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    Craig:
    I have recently purchased it and will get to put it through some tests in the next day or two. I have used the sweeps on AVIA previously and wanted something better. I'll post my impressions here as soon as I have used it.
    Deane
     
  5. Deane Johnson

    Deane Johnson Supporting Actor

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    Craig:
    I had a chance to use the Stryke's test CD this afternoon. I like it quite well.
    My test method is much less fancy, and not as much fun, as those that are being done with computer programs. I simply play the tones and record the result on a piece of paper using the Radio Shack analog meter. I do put it on a tripod in the proper location so I can sit to the side and see the meter.
    The Stryke's disc has a number of tracks on it, with each frequency being played for :30 seconds. This is plenty of time for the needle to settle down on the meter and for you to record the result.
    I used Excel to make a matrix. I used the first column to record the BFD Filter #, the second to indicate the Stryker track, the third to indicate the frequency. I then left a good half dozen or so blank to record results in. My final column has the meter correction factor for the RS meter. I can then go through my system, record what the meter reads, use the next column to calculate a net result after the meter correction is applied. I'm sure everyone might have their own way of doing it geared to their circumstances and equalizer.
    I have no way of knowing the accuracy of this disc any more than I do the AVIA or Video Essentials. I will say that it appears to me to be the work of someone who knows what they are doing and is very professional. I have confidence in it.
    I also use both AVIA and VE for various things, each having their strengths and weaknesses. It was the low frequency sweeps on AVIA that allowed me to discover I had a 16 db room spike at 42 Hz.
    The trouble with the AVIA sweeps is that they are a moving target. Impossible to record results from as they go by rather quickly. The Stryke's disc eliminated that problem and allowed me a much better adjustment.
    For what it costs, it is a very good value and a tool I will not be without from now on.
    Hope this helps you make a decision.
    Deane
     
  6. Steve_D

    Steve_D Second Unit

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    Deane,
    I don't have the Stryke disc, but your description of it and methods you use, even using excel, are exactly what I've been doing for a number of years with a disc called "surround Test CD".
    The only thing, does your tripod allow it to be in the sweet spot listener head location? I find I have to stand behind the couch, and hold the SPL meter where my head would be. Luckily, there's a pattern in the couch that allows me to place the SPL meter in the exact same position (give or take a mm or 2).
    ------------------
    http://www.sdiver.org
     
  7. Deane Johnson

    Deane Johnson Supporting Actor

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    I actually have two chairs with a table in between. Putting the meter in the middle probably isn't perfect, but I figure it averages the two chairs.
    Deane
     
  8. jeff lam

    jeff lam Screenwriter

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    I picked up the stryke cd a few weeks ago and it's very good. It gives you tones down to 10HZ. Great for testing SPL's at specific frequencies with a SPL meter.
     
  9. Bob McElfresh

    Bob McElfresh Producer

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    Are you guys talking about Stryke disk #1 or #2?
    Deane: when you start your test, what SPL and frequency do you start at to get you near normal listening levels before hitting individual frequencies? Do you just use pink-noise to get you near 75-85 db and then start the sequence?
    And once you find some bad peaks, do you then focus on that frequency and have someone move the sub a bit to tame it?
     
  10. Deane Johnson

    Deane Johnson Supporting Actor

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    Stryke Disc #1 is what I have.
    I haven't felt there was a need to do this at any specific level. With bass frequencies, I'd rather do them far enough down that I don't hit a resonate frequency and blow something. I usually just select a comfortable listening level.
    No, I don't move the sub. I did try that at one time, but found it didn't do much. Finding room response is different than finding a location for the sub that provides the best overall performance for the sweet spot. For me, the spikes and nulls pretty much remained the same.
    I used 1 Khz as reference, then did my charting of the low levels in comparison to that. I'm not sure that is even necessary. What you're trying to do is smooth out the response of the bottom frequencies up through the crossover point.
    If you write down the level at each frequency, you can then look at it and see what needs to be raised and what needs to be lowered. You'll have good luck lowering, but raising has to be done carefully. You can't correct a room null by boosting with an EQ. The cancellation is still there. All you do is over drive the subs amp and make it sound terrible.
    I use a BFD, so it's easy to assign a filter to each frequency throughout the sub range, then dial in the correction I need. For instance, I had a 16 db spike at 42 Hz. With the BFD, I could take a filter, set it to exactly 42 Hz and lower that frequency 16 db. At that point, I would then run the test again and rechart. This way I could do more fine tuning. I found that sometimes I would overshoot. In other words, lowering a spike 16 db might cause it to go down 20 db. I don't know why.
    One should not forget to add the correction factor for the RS SPL meter (assuming that's what you use). If you don't you're way off. The add amount is 7.5 db at 20 Hz for instance. Not doing the correction could cause you to think you were 7.5 db lower at that frequency that you really are.
    When I have the sub as flat as I can get it, I then set my sub level with VE. This I do at 75db for the mains. My sub is usually a couple of db or so above that. I used to run it 10 db above the mains until I took out the spike. Now it's so powerful overall, that running it closer to the mains works best.
    Deane
     

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