Why are there differences between receiver's and setup disc's test tones?

Discussion in 'Archived Threads 2001-2004' started by Matthew Anderson, Nov 19, 2002.

  1. Matthew Anderson

    Matthew Anderson Second Unit

    Joined:
    Sep 24, 2000
    Messages:
    281
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Garland,Tx.
    Real Name:
    Matthew Anderson
    When I calibrate the level between between my subwoofer and main speakers I get different results when I use the test tones in my preamp(Outlaw 950) compared to the test tones on my calibration disk(Sound and Vision's HT Tuneup). The preamps test tones indicate my sub is 2-3db above my main speakers but the test disc indicates a reading of 1-2db below my main speakers. I'm not sure which set of readings to go with, but I would think the ones on the HT disc are more accurate. Thanks for any input on this.
     
  2. Rich Malloy

    Rich Malloy Producer

    Joined:
    Apr 9, 2000
    Messages:
    3,998
    Likes Received:
    0
    Trophy Points:
    0
    I think it's simply this: different source components will output the signal differently and thus one needs to calibrate one's system utilizing tones that originate with the source component (rather than further down the line with the preamp/receiver) and which traverse each step in the chain all the way through the speakers and into your ears (or SLP meter).
     
  3. jeff peterson

    jeff peterson Supporting Actor

    Joined:
    Nov 29, 1998
    Messages:
    675
    Likes Received:
    0
    Trophy Points:
    0
    I think most agree to have the test tones originate from your source equipment. Cables may have different impdedences from each other, etc.

    Having said that; your specific diference may also be due to the receiver's test tones may be a different frequency than your test disc's tones. Especially in the lower frequencies, the Radio Shack SPL meter is "off" by as much as 3-5 dB depending on the frequency being measured.
     
  4. GregK

    GregK Screenwriter

    Joined:
    Nov 22, 2000
    Messages:
    1,026
    Likes Received:
    256
    Trophy Points:
    1,610
    I think Jeff hit the nail on the head when it comes to if the frequency is different, and/or if the test tones are wide band or narrow band as well.

    I'll disagree with everyone on the cable issue if (and remember the "if") the DVD's output is digital DD, DTS, or PCM, to a digital audio receiver, as cables will have NO effect on what output level a receiver decodes the audio internally. People can argue the merits of high $$ digital interconnects forever, but if the receiver gets the bitstream intact, the receiver decides the exact decoded output level of the decoded bitstream, not the cables.
     
  5. Matthew Anderson

    Matthew Anderson Second Unit

    Joined:
    Sep 24, 2000
    Messages:
    281
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Garland,Tx.
    Real Name:
    Matthew Anderson
    Thanks to Rich,Jeff and Greg for you input. This helps me understand the reason for the difference in readings.
     

Share This Page