Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 31

Thread: Audible Physics XR3M-LE and AR3K Driver Test Discussion

  1. #21
    Senior Member cvjoint's Avatar
    Join Date
    Mar 2011
    Location
    Northern California
    Posts
    801
    Real Name
    George
    Looks good to me, and very close to what the manufacturer has on their white sheet. I never doubted your results.

  2. #22
    Tester Extraordinaire ErinH's Avatar
    Join Date
    Aug 2010
    Posts
    1,247
    I didn't think you guys doubted me. It's just hard to know what to expect. I'm actually very pleased to see that matches. So far I'm 3 for 3 (the Audible Physics drivers closely mimicked the mfg spec). That gives me more confidence in my testing and build. Very refreshing from a standpoint of self-doubt and unknowing. Relieving seeing the hard work and time I put in have some payback and validity.
    I feel it's safe for me to proceed now.
    Your ears: The best tools you have... and they're free, too!

  3. #23
    Tester Extraordinaire ErinH's Avatar
    Join Date
    Aug 2010
    Posts
    1,247
    Ian, can you move this over to the data thread?...

    Harmonic Distortion for the AR3K:

    Driver installed on test baffle used for FR testing.
    The voltage out was 0.967, mic distance is 10 inches, which yields an 85.5d
    The test range for this data was 50-20,000hz, but limited on the top end by the program's apparent default of sampling rate. I'm gonna have to crack open a signal analysis book to get to the root cause. However, it's commonly believed that distortion above 10khz isn't very important because masking takes over.
    If you want distortion above the 12.5khz shown below I'll have to sacrifice low end. It's a trade off. I went for the low end distortion being shown as I think it's more pertinent; especially when you see the 3rd-5th order distortion trend on the high end (trailing off).B response @ 1 meter for the test. I wanted to shoot for higher, but I never realized just how damn loud 85.5dB truly is. I can literally hear the sweeps standing in my front yard. I may need to reconsider my idea of doing this kind of testing at 92-95dB. But, we'll see.

    If you're saavy, you may catch the boosted lower end in the fundamental; this seems to be an artifact of the room itself as distance and driver type did not result in a change in this trend. Additionally, I noticed Zaph's HD/FR results shared this same kind of characteristic. I'll look further into the root cause, though, but wanted to note that this was noticed by me and that I wouldn't concern yourself with that because the goal of these plots is to compare the distortion orders to the fundamental. IOW, the following data is relative in itself.
    IOW, don't look at the HD results for the FR; look at the FR data for the FR. ;)
    PS: Ignore the parameters on the right of the HD graph window. That section is used for driver mechanical/electrical linearity and they are default values; I did not use them and they were not needed for the HD sweeps.




    Expect to see the XR3M-LE HD data posted tomorrow afternoon/night.

    For discussion on HD testing, see Zaph's page:
    Zaph|Audio

    He says it much better than I could.


    - Erin
    Your ears: The best tools you have... and they're free, too!

  4. #24
    Senior Member cvjoint's Avatar
    Join Date
    Mar 2011
    Location
    Northern California
    Posts
    801
    Real Name
    George
    Output level is only 85.5db? I'd really like to see a lot more. That's the bk noise level in my car.

    There is a 5th order peak at the same spot as the FR peak. Can anybody make anything of that?

    Erin what's with all the nonlinear parameter windows and plots? Are you telling me this thing can do some of the things the KLIPPEL can?
    Last edited by cvjoint; 04-15-2011 at 03:28 AM.

  5. #25
    Tester Extraordinaire ErinH's Avatar
    Join Date
    Aug 2010
    Posts
    1,247
    You know, I thought the same thing about the drive level.
    So, here's how I arrived at the value I gave earlier. Feel free to verify with the numbers I gave:

    To figure out the drive level when doing the distortion tests I simply took the measured sensitivity (80 @ 1w/1m; which matched mfg), the voltage out of the amp (0.967; constant with only 0.001v variation) went into 3.60 ohms.

    The power would be 0.26w.
    The distance I was at was 10" (0.83 ft).

    Using this site to calculate, I get SPL of 86.1 (85.5dB earlier was rounding error).


    The numbers are there, but it just doesn't make sense... I know 86dB isn't quiet but this certainly seemed MUCH louder. Maybe I just need to calibrate myself. Maybe we all need to rethink just how loud 86dB is and we all really need to realize that most mics are not calibrated for absolute SPL; only FR (there is certainly a difference) so what we think is xx dB really isn't.
    I know this; when standing in my front yard at least 20' away from the house with the test room being upstairs, I could CLEARLY hear the noise. There is flat out NO WAY I'd be sitting in the same room as the driver during the test.
    Futhermore, when I started the sweeps, I would watch the driver's excursion to see if it was in check. The AR3K was clearly getting down to it in free-air.
    Last edited by ErinH; 04-15-2011 at 10:15 AM.
    Your ears: The best tools you have... and they're free, too!

  6. #26
    Founding Member 86mr2's Avatar
    Join Date
    Aug 2010
    Posts
    286
    Quote Originally Posted by ErinH View Post

    The numbers are there, but it just doesn't make sense... I know 86dB isn't quiet but this certainly seemed MUCH louder. Maybe I just need to calibrate myself. Maybe we all need to rethink just how loud 86dB is and we all really need to realize that most mics are not calibrated for absolute SPL; only FR (there is certainly a difference) so what we think is xx dB really isn't.
    I know this; when standing in my front yard at least 20' away from the house with the test room being upstairs, I could CLEARLY hear the noise. There is flat out NO WAY I'd be sitting in the same room as the driver during the test.
    I think that the distortion products are responsible for much of that effect. Generally, sensible people are trying not to listen to the driver in the ranges where the distortion is uber-audible. The distortion test and FR sweeps cover that range. Just look at the peaks of the FR vs the "useable" range and consider how much of that peak is the contribution of ear-jangling odd-order distortion products.

    I have heard a great many stock systems and systems built with $80 (or less) paper coned coaxials sound incredibly loud from inside (or driving by) with just deck power. My system actually sounds quite quiet from outside.

  7. #27
    Tester Extraordinaire ErinH's Avatar
    Join Date
    Aug 2010
    Posts
    1,247
    I don't disagree... I'm just not quite sure of that aspect. Though, I'm certainly not writing it off. It is something to consider.

    What has me most concerned is that if what I measured was only 86dB... well, 92dB is going to wake the damn dead. However, the Scan test, which was at ~95dB. I didn't think it was too terribly louder than the A-P driver, which may actually coincide with what you're saying. I'll chew on that, yo! ;)
    Your ears: The best tools you have... and they're free, too!

  8. #28
    Tester Extraordinaire ErinH's Avatar
    Join Date
    Aug 2010
    Posts
    1,247
    Guys, due to advances in the test setup (ie: absorption panels, set in stone-ish requirements) I've started new data threads and deleted the old one:
    http://www.mobilesoundscience.com/f1...698/#post10416
    http://www.mobilesoundscience.com/f1...700/#post10418
    Your ears: The best tools you have... and they're free, too!

  9. #29
    Big Daddy Chad's Avatar
    Join Date
    Aug 2010
    Location
    East-Central Illinois
    Posts
    1,570
    I REALLY like where this is going

  10. #30
    Founding Member
    Join Date
    Aug 2010
    Posts
    61
    Nice job, Erin! These are great data, and really appreciate the attention to detail you're showing with this endeavor. Keep up the great work!

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •