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vibro veritas, measuring our IEMs like a pro with amateur budget.

Discussion in 'Sound Science' started by castleofargh, Aug 12, 2015.
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  1. castleofargh Contributor
    well consider, from 0.5V to 1V it's +6db.  so I guess you can enjoy this "horribly wrong" value at 1khz without too much worries for most practical uses ^_^.
  2. CraftyClown
    Haha, I thought it was close enough, but I had to ask.
    I'm afraid I still need you to help me take baby steps through this though as I'm not 100% sure of what else needs to be done.
    So where I am right now;
    1. My DAP is playing a 1khz tone through my IEMs.
    2. I have removed the right hand monitor to reveal the 2 pins at the end of the cable
    3. I am attaching the two prongs of the multimeter to the 2 pins on the cable and attenuating the volume until the meter reads approx 2v
    4. Now what?  [​IMG]
  3. castleofargh Contributor
    0.2v !!! if you're going to use the values from the er4's measurement certificate. it's the only reason we pic this, it's the value Ety used, nothing more.
    then you plug the er4, put it into the veritas set up whatever it is you think you need to set up and in REW you use the SPL meter for calibration. calibrate with external signal to use the test tone into the IEM(so that it measure 1khz only) and just enter 104db or 104.5db(whatever your certificate gives for that er4 driver fed 0.2V) and you're done.
    now when you measure something, you can read how loud it's going directly on the measured graph.
    it makes things way easier for measurements afterward to do them all at about the same loudness, make sure you're not killing your IEMs with 130db or simply to have meaningful values on the graph and calculate the actual sensitivity you're getting compared to specs(like Tyll does).
    CraftyClown likes this.
  4. bartzky
    Okay, I try to make it as easy as possible for you [​IMG]
    1. Don't take your DAP. It probably has high-z out. Take the 0.47 Ohm out of your Geekout.
    2. Use a Y-splitter
    3. Use one output of the Y-splitter for your ER4 and the other one for a cable like this:
    4. Connect your multimeter to cable 3. from GND to left or from GND to right (doesn't matter).
    5. Play the 1 kHz 0dBFS file in loop.
    6. Adjust the volume to 0.2 V aka 200 mV and for god's sake do not feed your IEMs with 2 V!!!
    7. Go on with what @castleofargh has written in post #78.
  5. CraftyClown
    Brilliant, thanks guys 
    If the output impedance on my DAP is low enough, ie less than 1 ohm, would it be ok to use?
    also 2v was a typo [​IMG]
  6. bartzky
    Should be okay then, but I really don't know how you would use a DAP with REW...
  7. CraftyClown
    I'm probably being a doofus here and missing something obvious, but why would it matter as long as the veritas is connected to the PC and is being recognised by REW?
  8. csglinux

    USB DAC mode??

    BTW, those of you using REW, how have you been adding your diffuse-field corrections? Have you done this via the generic (file-based EQ)? I presume if you didn't care about the raw measurements, you could bundle all corrections into the soundcard calibration file, but I think I'd rather keep those unadulterated raw measurements. What's the best way you've found to produce both curves?

    I've found my raw measurements quite close to those of Innerfidelity's, except beyond 10 kHz, where the Vibro Veritas mic seems less sensitive and shows a faster roll-off.

    Ooh. One other thing I forgot to mention about my VV coupler. I also coated the inside of it with UV6800. The way it was printed, it had a sort of discontinuous seam or ridge running down the length of the inside of the coupler (in the axial direction). The texture of the UV6800 glue is a little rubbery and helps to get a consistent seal.
  9. csglinux

    I'm also being a doofus. My X7 seems to be working fine with REW. I didn't want to use my soundcard to also drive my headphones, because its output impedance is too high for some of my IEMs. My X7 seems to be working fine. I hope I'm not committing some terrible engineering error here!!
  10. bartzky
    That's a valid point, but not every DAP can do this.
  11. CraftyClown
    I wasn't going to use it in USB DAC mode, but if I'm purely using it to test the SPL of my IEMs then why would I need to?
  12. bartzky
    As soon as you need to use REW.
  13. csglinux
    @bartzky, have you ever used .req files with REW for EQ/correction? These are binary files, so I've having fun editing them :wink: Is there an easy way to make up and import parametric EQ files? 
  14. CraftyClown
    What am I missing here?
    When I open REW and go to the SPL meter it is reporting back the SPL of my microphone input which in this case is my Veritas.
    If the IEMs I want to check the desired listening level of are playing back a 1khz tone from my DAP, what would be the problem?
    Once again I'm sure this is me being an idiot, but if you could explain I would be grateful  [​IMG]
  15. bartzky
    I tried to use it.. I thought like "hey I have got two different IEMs - can one possibly make them sound the same?". I thought two sets of measurements and REW were the weapons of choice. Sadly I found it to be much to complicated so I ended up using the ADI-2 Pro's EQ.

    If you ever find an easy way: please tell me :D
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