Have some questions on hoe to get a house curve for my SVS????

Discussion in 'Archived Threads 2001-2004' started by Mark Guidry, Mar 15, 2002.

  1. Mark Guidry

    Mark Guidry Stunt Coordinator

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    Well I do not have a BFD or an EQ at this time. I actualy just got my SVS subs and I am still trying to tweek them with what I have. I want to make sure I calibrate them right and then get a responce so I can see if I need a EQ or even if an EQ will help. I do have some questions about how to get a house curve. So I set all the speakers to 75dB's (85-85 for the subs) using a calibration DVD so I will have my "refference volume" and then:

    1. I will need to use a test CD that has test tones on it for the subs....I have a program that will generate sign waves that I can burn onto a CD...will this work???

    2. If that will work what tones do I need...should I use the same set that SVS has on there web sight that you use for the correction values on the RS meter...like 10 Hz, 12, 16, 20, 25, 31.5 Hz, 40, 50, 63, 80, 100, 125 Hz??

    3. Do I need the tones the are not on that correction list like between 25Hz and 31.5Hz...if so are there any correction values for them or are they correct???

    4. I do this measurement in the listening position that I used to get the "reference volume"??

    5. What volume do I do the test at...do I use the "reference volume" or do I start off with one tone like 31.5Hz and adjust the volume on the receiver till the meter is at 80Hz then move up and down the range and record the readings???

    6. What tone should I start with the highest or the lowest or does it not matter???

    If there is anything else you can tell me that would be great!!

    Thanks

    Mark
     
  2. Steve_Ma

    Steve_Ma Second Unit

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    Mark,
    If using your internal test tones, calibrate all to 75db, with your master volume set to 0. Including the sub. The material/hardware automatically adds the 10db boost for DD signals. See this thread going on in the AVS forum for more details. I'm steve6387 in that forum, btw.
    http://www.avsforum.com/avs-vb/showt...hreadid=125318
    Second, I just ordered the Stryke CD (hope to get it this afternoon). http://www.stryke.com
    You might want to consider it as well. This will allow you to identify what your sub is doing in your room, and at what freqs.
    As for the volume level when performing the tests. Someone will correct me if they think I'm wrong here but....The volume really doesn't matter, as long as it is constant. Reference level volume will likely be to high. At that point, you would have already calibrated your equipment. The master volume (I believe) is not the issue. What is happening at any given volume is, however, the real issue. That is what the Stryke disk is for. Turn the volume to a point where it's comfortable and start playing various test tones and recording the SPLs.
    Good Luck,
    --Steve
     
  3. Mark Guidry

    Mark Guidry Stunt Coordinator

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    I didn't calibrate the speakers using the internal test tones...I used the ultimate platinum DVD for this.

    Ok so do you think the Stryke disc and the home made CD (the one I make using the sign wave generator on my comp)would be the same. I can pick any Hz I need to record on the CD.

    So the volume is not that important...just as long as its constant?
     
  4. Steve_Ma

    Steve_Ma Second Unit

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    I have no exp with the ultimate platinum DVD, so someone else should be able to give you better advice.

    The Stryke disk and the homemade one you have should do the same thing. Play tones at known freqs to measure ouput. Assuming your system is calibrated, it'll definately tell you what's happening in the room. I don't have a burner and I liked the idea of waiting a couple of days to get a disk with all the tones (sine and warble) that I'll ever need, so for me...the $11 was worth it.

    As far as the volume when performing the tests goes. I'm sure there could be some minor differences at extreme volumes due to distortion, but my sense is this would be minor compared to your real measurable results and goals. You will be able to measure peaks and null spots up and down the spectrum, regardless of what the master volume is set at. A peak is still a peak, whether it's at 95 or 75 on the SPL meter.
     
  5. Mark Guidry

    Mark Guidry Stunt Coordinator

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    Ok sounds good so far...anymore input from anyone[​IMG] [​IMG]
     
  6. Rick Radford

    Rick Radford Supporting Actor

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    Mark,
    I tried to respond here earlier today but the proxy server I was working thru went down and I lost my reply.
    IAC, read the excellent info at Sonnie's site.
    Especially scroll down to this section:
    MEASURING SUB SPL LEVELS & USING MICROSOFT EXCEL WORKBOOK
    Sonnie has references to test tones and other helpful info. The info on this web site is geared towards manually collecting the data.
    I also know nothing about the ultimate platinum DVD you referenced. But in addition to the test tones (if you do this manually) or ETF (if you automate the data gathering process), get Avia and/or VE to help you properly calibrate your HT setup. If you want to know more about ETF, do a search here and you'll find LOTS of info! Look especially for an ETF review that brucek did a few weeks ago.
    Calibrate now and check your room response. Post the graph here if you'd like others to comment.
    BTW, ETF uses MLS tones. You can't use a test tone CD with ETF. The MLS tones ETF uses are generated by the software itself through your sound card on the PC. So you'll have to move your PC into your HT room (or use a laptop) to record the data.
     
  7. Wayne A. Pflughaupt

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    Mark,
     
  8. Mark Guidry

    Mark Guidry Stunt Coordinator

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    Hey great info guys!! I think I am just going to order the AVIA disc and the Stryke CD as well...I was just going to try to use what I have but I would rather have it just right! I will post the results when I get them and get some more help from yall!!

    Thanks

    Mark
     

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