Measurement Setups - Post Your Rig!

Discussion in 'Measurement Setups, Systems, and Standards' started by Luckbad, Oct 5, 2015.

  1. Philimon

    Philimon Friend

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    [​IMG]

    Im not going to use my 6XX to calibrate since its modded so could be imbalanced with all the hastily cut and pasted dynamat. I need to look up how to average sets of data and how to overlay. And does REW + EARS do CSD because I couldnt get it to display. Its been a while since I used REW and its changed a little... I had used it previously to help dial in my car audio back in 2012(?). I dont think it was even available on mac back then.

    Will be applying SBAF comp to HEQ once Ive gotten a better handle on REW and headphone positioning.
     
  2. Philimon

    Philimon Friend

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    [​IMG]

    [​IMG]

    Had to give it a try with 6XX since it was already setup. The imbalance is strong. Probably mods and positioning. I took 4 strongly varied placement measurements and applied HEQ (v2?). I think garbage truck was coming by when I took the L measurements. The 6XX mod is KISS with naked driver vent and 580 headband (loose clamp). FYI I've never noticed an imbalance myself when listening but Ive not really tested for it. My guess would be that dynamat is placed a tiny bit closer to vent hole on one side vs other.
     
    Last edited: Oct 26, 2020
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  3. Lyander

    Lyander Too sensitive for SBAF

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    Have you tried reversing the headphones on the rig and then measuring? Alternatively you could just disassemble the headphones and couple the individual cups to ears— the angling of orientation could also account for a lot of the difference. Just make sure that you have them positioned identically on both sides since that accounts for a lot of variability in measurements. Maybe do averages of multiple sweeps?

    Also yeah what are you driving the headphones with here? I've started doing measurements at higher SPLs just to get past possible channel imbalances on the Fulla 2/Liquid Carbon, think that may play a role? Of course if these were taken at your listening levels (seem kinda high but eh who knows) then maybe minor imbalance is to be expected.

    EDIT:
    Yes REW with EARS does CSD, but the rig generally isn't great for much beyond FR and maybe some distortion, if you know not to take those latter squiggles at face value— there are some massive resonances that are more representative of the rig than headphones, IMO, though there's probably something to the fact that not all headphones elicit the same reactions.

    REW has changed a bit in the time since I've started using it just a couple years back but the general layout appears the same. CSD is under the "Waterfall" tab third from the right in the results window.
     
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  4. Philimon

    Philimon Friend

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    Thanks. I'll try switching drivers around to see what that does. Measurements were made without much regard to positioning consistency - I just wanted to give it a whirl. Still, that 4-5k range is pretty consistently different from L to R, but we'll see...

    Next set will be more serious and I should have the SBAF comp applied by then. Will do T-X0 and Porta Pro for more context, see if L/R differences remain. And thanks for the heads up - I'll not mess with CSDs then. And too bad distortion is not going to be great either.

    Using Vali2 with 6N23P-EV. Imbalance is clear below 9:00 on volume knob. I have it set to 10:00 and adjusted the gain switches on EARS to 12db (or maybe it was 6).
     
  5. Lyander

    Lyander Too sensitive for SBAF

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    Well I mean CSDs and distortion won't be great sure, but it's still data that can be useful given proper context— *insert profound quote about how integrity, experience, and methodology can matter more than tools used here* :p

    I think it was @james444 who suggested that using IEMs to check for channel balance issues may be more effective, as you need only have a care for insertion depth and housing position then. I can't well do the same since the mics on mine are now flush with the "ear canal" opening but it may prove useful all the same.
     
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  6. purr1n

    purr1n Finding his inner redneck

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    There can be some minor imprecision, even with the supplied HEQ files applied.
     
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  7. Philimon

    Philimon Friend

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    I've done something wrong. A wrong setting or added when I should have subtracted... Please help?

    I moved this data to txt and applied to 6XXmodded measurements in above posts but the resulting graphs looked not right.

    [​IMG]

    [​IMG]

    6XXmodded uncompensated (please ignore titles.):
    [​IMG]

    6XXmodded HEQ:
    [​IMG]

    6XXmodded SBAF compensation
    [​IMG]
     

    Attached Files:

  8. Lyander

    Lyander Too sensitive for SBAF

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    Just from the fact that there's a massive trough a bit above where the EARS rig's peak usually is makes me think that the compensation might have been transposed up a few lines? No idea what went on in the bass though, that's too drastic a change and the sub still looks rolled off.

    As an aside the raw results look perfectly fine but the supplied HEQ compensation (black trace underneath red measured FR) seems to have a less massive bass shelf than before. Maybe the 20dB scale just makes it seem that way? Weird.
     
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  9. Philimon

    Philimon Friend

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    SN 860-1046

    If its not too difficult for someone to create the sbaf compensation txt file for me I would much appreciate. :D

    Ill look again at my handiwork but it looks okay from another glance... I may just also messed up a setting in rew?

    Im going to measure a couple more headphones this morning and share the raws and HEQs, overlay L/R, see about averaging, and more y-axis detail.

    EDIT: @Lyander computed my sbaf comps for me. And @Biodegraded offered the same. :bow:
     
    Last edited: Oct 27, 2020
  10. Philimon

    Philimon Friend

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    The HEQ files are noted as version 2. Is this new?

    EDIT: version2 is from march 2018, so not new. “More neutral in bass.”

    EDIT2: I triple glanced my numbers and they look fine to me, but obviously something's wrong. Will update later after I've ran through setting up REW again with new measurements.
     
    Last edited: Oct 27, 2020
  11. Lyander

    Lyander Too sensitive for SBAF

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    Could you send over a sample measurement for L+R in .mdat as well? Not necessarily averages, just positioned similarly as possible between left and right, ideally the same cup etc so people can eliminate imbalances inherent to the headphones. Yeah I think Etymōtic IEMs would be grand for this since they may be easier to seat consistently hahaha.

    5db increments on y axis may help key things in, but that could just be my nitpicky ass talking.
     
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  12. Biodegraded

    Biodegraded Friend

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    I think something's off with your Excelling. The final comp curve should look something like this (this is Marv's L, it'll be slightly different for your unit because the original HEQ will be slightly different):

    [​IMG]

    Check the results (under the green banner) in your Excel sheet between c. 4 and 9 kHz to try to figure out where the negative numbers are coming from - they should all be positive. Correcting whatever's responsible for that error should solve the weirdness in the bass too.
     
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  13. Philimon

    Philimon Friend

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    Ugh. Set back. REW is not outputting any audio with generator. I messed with mac audio midi settings to try and change the EARS gain to 0db as per instructions. Yesterday, I left it at default 24db because it would not allow me to alter the values and so instead I changed the gain switches on the mic to 6db to help compensate. Same issue today with not being able to change EARS gain but then I effed with some other settings while I was in there - not sure what I did. Anyways, my other programs will play audio but not REW. I reset REW preferences to default, and restarted laptop but no luck. And now I have a headache because I accidentally played some sine sweeps over laptop speakers. Will try on windows laptop instead next time.

    Edit: Low content post needed some saving grace. Headphones assemble! .pic

    [​IMG]

    Grado Hemp expected today too. Wooh
     
    Last edited: Oct 27, 2020
  14. Bill-P

    Bill-P Level 42 Mad Wizard

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    Just for a data point, this is with my EARS, default HEQ compensation:
    [​IMG]

    Fun fact: I actually have to boost the left channel by 2.5dB exactly to get those. They look... close-ish but yeah, you can see there are slight differences across the entire frequency range.

    Here's how the exact same headphone measures like with just the right ear:
    [​IMG]

    I'd say... differences between left and right are there. What I did was I took measurements with the exact same side of a headphone on both ears (pretty easy to do with HD650, if I may add), then I took the difference and applied it to the left ear compensation + added the 2.5dB offset. Boom, now it's far more consistent.

    The EARS is cool, but consistency can be quite an issue...
     
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  15. Philimon

    Philimon Friend

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    Fostex T-X0

    I took two measurements with slightly altered positioning trying to be mindful of symmetry and seal. My laptop's fan may or may not have been on during these runs. Its a cheap pos asus 'rugged' gaming laptop and my cords are only so many feet in length. 1 and 2 are measurements1 of R and L respectively. 3 and 4 are measurements2 R and L respectively. I could upload mdat if interested. 6XXmodded redux up next.

    Fostex T-X0 overlay SBAF comp.jpg Fostex T-X0 overlay uncompensated.jpg
     
  16. Philimon

    Philimon Friend

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    Improvements are this time I did 1=L and 2=R . I forgot to see about adding more Y-axis detail and apparently forgot to add a title. Top is SBAF compensated and bottom is uncompensated.

    Next will be 6XX drivers switched. Also, amazing how 6XX unsmoothed is way smoother than T-X0 with 1/12 smoothing applied.

    Sennheiser 6XXm overlay SBAFcomp.jpg Sennheiser 6XXm overlay uncompensated.jpg
     
  17. Philimon

    Philimon Friend

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    So, improvements to be made: fix the legends, and find out why y-axis goes to intervals of 20 when it show intervals of 10 during the take a pic function.

    Porta Pros were difficult to place. And the way they rest on EARS' ears may not be same on human ears. The Porta Pro has little extra foam pads that are for resting against the temple(?) and act as a bit of support and pressure relief for headphone clamp. Not sure how this lack of extra clamp relief would show in EARS measurements.

    I skipped 6XX swaps measurements for later because when I went to swap the drivers I remembered that the extra dynamat mods kind of make it difficult to remove grill so quickly. I placed extra dynamat beyond KISS recommendations because I hoped more would be more better. And since I liked the way zero driver vent foam sounded overall - I felt more mass (dynamat) would help control and balance the excess bass created by zero driver vent foam.

    Edit: A couple more headphones to come. Hemp got delayed to Friday unfortunately. And I'm going to order a 5XX @purr1n recommendation. However, he did not catch the 4XX's steely timbre in it's original review... Will the same subjective feels occur with 5XX and it's suspicious treble peak?

    Koss Porta Pro overlay SBAF comp.jpg Koss Porta Pro overlay uncompensated.jpg
     
    Last edited: Oct 28, 2020
  18. Philimon

    Philimon Friend

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    Beats EP. A small supra-aural closed headphone with leather earpads (hybrid actually, the interior is cloth / some porous material). Placing these and getting a seal was really difficult and I had to cheat by applying pressure. I am unable to get consistent results. See rtings frequency response consistency chart for example.:
    https://www.rtings.com/headphones/reviews/beats/ep

    Taking a break. May come back with some cheap ear buds and iems as @Lyander recommended to reduce positioning as a variable.

    Question, I'm having trouble calibrating my spl meter to the recommended 40db (or whatever). It seems my setup is too loud for whatever reason. Can I just reduce sine sweep levels?

    Beats EP SBAF comp.jpg
     
  19. Lyander

    Lyander Too sensitive for SBAF

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    The -40dB thing is to calibrate the mics on initial setup yeah? Err if memory serves you're not meant to target 40 dB, it's more just keying in sensitivity on the mics. 40dB isn't exactly feasible in a lot of settings because... ambient noise.

    Set up the tone generator and run a sine wave at 300Hz with output at -20dB using the sensitive side (yours is Right channel) then adjust volume on whatever amp you're using until you meet the calibration target.

    Sensitivity factor on both L and R for you is 0.2dB so just run the above and tweak your volume until you get there. Snip below taken from the manual, it just so happens that they're also targeting -40.2 here, which is what you should be reading if you set stuff up as in the second paragraph properly.

    MiniDSP setup.PNG

    https://www.minidsp.com/images/documents/EARS User Manual.pdf
     
    Last edited: Oct 28, 2020
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  20. Biodegraded

    Biodegraded Friend

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    Comps now look about right. Modded 6XX looks pretty nice; some or all of that apparent channel imbalance might be the due to the MiniDSP compensation files like @Bill-P said above so swapping sides might be informative.

    If you're measuring at 85-90 dB, change your vertical scale limits ('limits' button on top right of graph window) to something like 60-110 dB, then you'll get 5 dB graduations. And smooth everything 1/12 (or more).

    Also if you write titles in the little boxes at the top of each measurement in the left-hand panel, that text will turn up in the legend at the bottom.

    Looks like @Lyander has you sorted for calibration. But If you want to check it, there's a 94 dB = -16 dBFS file here.
     
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