Recent content by jesperlykke

  1. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    I see... thanks... So A is just a calculation i see, makes good sense. Will dig some more into this next few days :) Jesper.
  2. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    So after some time, I stumbled upon the (A)weighted measurement. I'm not aware of which kind of numbers I got using my calibration file as pr. instructed here in post #16 to #18. Or is it possible to change something and get (A) measurements or do I allready get that. I'm having problems...
  3. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    I accept that, also that it's correct. So anything above my ADC's 0dbfs level (around 1.339v) will be shown as +dbfs I did know that, and I also realize that it's not making sense what I asked as an option for REW. Jesper.
  4. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Hi... A ran some test, to try the two different calibration techniques out. All test is with Victors 998Hz oscillator @ 2.1V sine. The Notch is the Cosmos APU adjusted to -41dB / 998Hz. I carefully calibrated the voltage levels in REW before I started the test's. I'am in no doubt, that I would...
  5. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    This is really great... After some hour's with trial and error I finally got it right. (Notch is dual fliege OPA1662) This is the way I did it for the result's (see pictures for better explanation) : 1. Adjust Analysis. 2. Take measurement with notch and without notch. (-25dB - Full input...
  6. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Yes... this is excatly how I use my passive notch ----> My other thread regarding passive notch This methoed is working as expected. I will make some test, and compare them and post them here afterwards. Jesper.
  7. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Great... So you suggest me to try it out adjusted so that the TOP of the notch (away from the notch) is adjusted to 0 SPL instead? - Please see picture. Or should I do as I did with my passive notch the trace arithmetic (Notch response / No notch response (soundcard loopback) BTW. Is it...
  8. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Hi here... As I said, proberly need to have some more cleared out. I created a "mic. calibration" / notch compensation file, as Archimago do. Link ----> Archimago notch compensation (It's just to allign the measured notch SPL to 0 via. add offset in the SPL & Phase dialog + export measurement...
  9. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    So this is solved now :) Allway's help John, thanks... Tried to do a couple of 4M / 48kHz sweep's... Notch is >70dB deep I will proberly ask some more quistions regarding the calibration file Jesper.
  10. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Is it the Decimate IR checkbox. Sry. I'am not knowing that much about that YET :T
  11. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Okay... That's something I did not know. I will post back with my findings. Jesper.
  12. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Hi trobbins. I did try to lower the span to 900Hz ---> 1100Hz, giving the same result. I tried to step through the notch with RTA / FFT with 1Hz step's, showing me that the notch is -70dB deep, but I don't know howto do that in "measurement" ? Jesper.
  13. J

    Measuring freq. response with a deep notch, cannot measure the correct depth.

    Hi here. I'am trying to measure an active 998Hz notch, where the notch deep is around -70dB (very sharp). If i'am measuring it with the RTA / FFT function in REW with my soundcard, I can tell by the numbers, that there are at least -70dB between 998Hz and 8000Hz(way outside the notch) So I can...
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