Measurement Setups - Post Your Rig!

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

  1. Priidik

    Priidik MOT: Estelon

    Friend BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    1,943
    Trophy Points:
    113
    Location:
    Estonia
    cheap speaker imp.jpg
    Sure there are CLIO and AP etc, all $$$$+. However:
    Cheap soundcard and some junk bin contents.
    Important features are two separate inputs and when possible,
    low impedance line out / hp out (for this unit I bridged the hp out 100 ohm resistor internally with a 1 or 2 ohm resistor),
    or external amp that can supply some more current for speaker stuff.
    And REW with a computer.
    That's it. One can now measure impedance (and phase) of transducers.
     
  2. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Lambskin pads from eBay. There are two listings for these pads, one says "premium" and costs an extra $10. Could not tell the difference between the ads besides those two details. I purchased from the cheaper listing.
    https://www.ebay.com/itm/High-End-Replace-Ear-Pads-Cushions-Cups-For-FOSTEX-TH610-TH500-TH900-Headphones/253331486342?ssPageName=STRK:MEBIDX:IT&var=552869869256&_trksid=p2057872.m2749.l2649
    They are about the same thickness as the AHL and stock pads, but use a softer memory foam with slower rebound. They do not include a plastic attenuation ring. Quality is lower: the stitching is a little less dense, one pad has some stress showing on the leather.

    From the graph we can see one side has maybe less seal. This is not from bad placement. The memory foam and flat shape allow easy seal with EARS. I'm going to say its leaky pad from bad stitching, but don't know for sure. Not going to troubleshoot. I'm ready to move on to baffle mods. Will continue with AHL pads.

    Quick listen: more v-shape. Comfort is okay. They offer more contact/support, but feels a little claustrophobic.

    EMU Lawton ebay lamb pads.jpg

    Update on YHD3. Some pads arriving tomorrow. I tried opening up cups but no luck. Prying apart the glued together front/rear baffles would not budge and it looked like plastic getting stressed and about to break. I'm probably doing it wrong. Unfortunate, since these need to be opened to be cleaned of the deteriorated foam/gunk particularly those plugging vents, and needs to be re-damped. Will probably just put some filter over exterior of back vents for some damping (lame).
     
  3. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    60mm velour pads
    Sound is not bad, but comfort is bad. Stiff foam and the headband clamp became too much. I could probably bend out some though. Also smelled strongly of chemicals that smelled like ant poison.

    YHD-3 velour.jpg

    Geekria L-pads next.

    Edit: Geekria L-pads bass-lite. Did not bother to measure. Did not fit well either.

    Will try a variety of small foam pads with thicker densities (besides center hole). I was negligent and destroyed my TTVJ deluxe pads so can not use. Kind of want to try opening shells again but first loosening adhesive by heating up. Not sure if this is okay with driver, so would check first.
     
    Last edited: Feb 3, 2021
  4. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    6,055
    Trophy Points:
    113
    Location:
    Vancouver BC
    Here's my impedance loop for headphones & earphones, for an SE in/out setup:

    [​IMG]

    This measures R channel (the wire colours of the skinny ones are non-standard, if the photo seems confusing). -ves all tied together, R +ve from phones & to input tied to one end of the resistor, R +ve from amp and L +ve to input tied to the other end. Instructions for use in REW are here.

    This resistor is nominally 100 Ohms but should be measured for best accuracy and the value entered into the box on the measurement screen (98.7 Ohms in my case). A little 1/4 Watt thing like this is fine for headphones. Make the measurement at a level at least as high as the SPL that you'd do FR (>85 dB) to minimize noise in the result.

    If you want to use the result to see how different amplifier output impedances will affect your phones' frequency response, you can use the spreadsheet linked here (instructions on the first tab). You can see results relative to a real FR measurement (pasted into the 3rd tab) or relative to a faked flat response generated by entering the same number in every field of the 3rd tab's SPL column.
     
    Last edited: Feb 3, 2021
  5. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    [​IMG]

    [​IMG]

    [​IMG]

    6XX JUG.jpg

    6XX JUG (2).jpg

    Called current mod JUG(head) because wanna be like JAR. Added more damplifier particularly around magnet. Then butyl tape on edges of baffle - used grill as guide and clamp. Don't sense any added closed-ness, sounds smoother overall.

    * Messy white adhesive spots leftover from another mod. Too lazy too clean.

    Don't know if adding the extra mass was more impactful that controlling reflections in cup/grill. Edges of cup/grill are not open; a surface for reflections. Butyl tape basically blocked off this area. Guesses. Thank jeebus for EARS. I measured 4times and 4placements each side. Left side is prettier as usual.

    Edit: Just noticed in comparison graph that 6XX “fake” is measured without grill. It says “fake” in reference to aftermarket knock off pads. Both measurements used these pads.
     
    Last edited: Feb 12, 2021
  6. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Retrospective
    6XX mod then now.jpg
    Both mods use no driver vent foam. Current mod uses no front-side foam, veil literally removed. :D I want to try rear driver vent foam again but removing the cups is now difficult. The butyl tape is much stickier than expected.
     

    Attached Files:

  7. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Well, removing cups wasn't too hard, but it totally pulled away and destroyed butyl tape mod. It's simple to redo, but later after driver vent tune. Went extreme and did micropore tape first for fun. Subjectively sounds lean as seen. Next will try a thin lite foam. Still no front foam btw.

    6XXm micropore rear driver vent.jpg
     
  8. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Bass tighter. Without front foam and dvf sound is too lean and peaky. Also, used thinner strip of butyl tape for cleaner install.

    Squigglies in bass probably from passing vehicle.
    6XX JUG dvf vs no dvf.jpg
    *dvf = driver vent foam

    Sounds good - I hope it lasts. Back to modding YHD3.
     
  9. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Tried adding more dense foam to back of YHD30i cup to try and flatten frequency response. Looks/sounds like it just flattened bass, so more roll off and less masking of upper mid and treble peaks. I ordered recommended eye pads. The shape of those pads are not round which is why I didn't try originally with YHD-3 original round enclosure. Shape matches well with KHP-30i, plus much cheaper than TTVJ deluxe pads for I imagine a similar effect: more seal while maintaining close driver to ear distance. I previously tried velour pads which sealed more but pushed the driver too far away from ear... If new pads don't work, then I'm going to try some flat leather pads next.

    YHD-30 mods more.jpg
     
  10. JohnM

    JohnM Author of REW - Rando

    Joined:
    Dec 13, 2015
    Likes Received:
    134
    Trophy Points:
    33
    Why the inverse C compensation on your measurements? That would typically only be used when measuring with a C-weighted SPL meter, though if you have a mic cal file loaded it will only affect results outside the cal file range.
     
  11. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    :bow: I’ve been checking c-weight box - bad habit. I do apply mic calibration file / compensation unless otherwise stated. I’ll stop doing that since I didn’t realize it was showing in the legend and adding confusion. So, that’s what “INVC” means... :oops:
     
  12. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Materials: Umik-1, paper towel, 2layers of closed floam, 1layer of thin felt, glue, tape. Ill add a layer of thicker felt or dense foam if needed.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  13. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Unable to find my Umik-1 calibration file so emailed Minidsp support. Until then, what "controls" settings should I be using for CSD waterfall. I tried looking at other's examples but can't get my graphs to look the same. Another question is how quiet does my environment have to be for dependable measurements? Should I make an isolation chamber, or shove the rig in the linen closet with the door closed, or is just out in the open like how I do with EARS for frequency response still okay?

    edit: On first page. Ill try that.
     
    Last edited: Jan 26, 2022
  14. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    6,055
    Trophy Points:
    113
    Location:
    Vancouver BC
    This is a combo of what I've seen others use. 100 ms window gives sharper peaks than 10 ms. The XYZs are from @Serious ; they give a nice persepective and labelled time graduations out to 5ms when you run it. If you measure at SPLs higher than 95, adjust the graph axis limits and colour scale to suit.

    [​IMG]

    It's recommended to pull your mic in so it's flush with the felt. Also - how is it held, by the closed-cell foam? might want to support it internally with squishy foam inside the tube instead. I find with my mini Dayton, securing it by the outer foam gives a bump in the mid to upper bass Just letting it be supported by the foam block leads to low bass rolloff, but more even and coincident with other's couplers above that.
     
  15. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Thanks for that @Biodegraded . I was still having difficulties with ultrabike’s tips.

    The mic is supported only by the 2layers of foam and thin adhesive felt. The closed cell foam is dense and stiff. I drilled holes smaller than the diameter of the mic that way when inserted it would be a tight fit for better seal. I had meant to wrap the mic in foam but forgot. I was rushing.

    After I try some measurements with the fpc Ill overlay them with EARS measurements for comparison. From there we can see what tweaks need to be made. But until I get the calibration file from minidsp I am kind of stuck atm.
     
  16. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    Test 1, fpc vs EARS, BP800.jpg
    ^ Mic is not flush with coupler - its as shown in pics where it's sticking out like 1cm. EARS is using SBAF compensation. Umik-1 does not have calibration file. This exercise was just for fun. Next test will be with calibration file hopefully within next couple days, then align mic to be flush.

    My fpc is approximately 2 inches wider than EARS. This could mean stronger clamp pressure on fpc which could be some of the difference in Test1 comparison. Should I make the pfc same width as EARS? I purposely went wider because I found some headphones (like TRX00) were difficult in getting a seal with the narrow EARS coupler.
     
    Last edited: Jan 26, 2022
  17. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    The Umik-1 calibration file didn't help much.:
    BP800 fpc test1 VS calibrated  VS EARS.jpg
    ^ Matched at 1kHz

    For test2 I'll move the mic to be flush with coupler.
     
  18. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    6,055
    Trophy Points:
    113
    Location:
    Vancouver BC
    To compare the FPC and SBAF-compensated EARS measurements, align at 100~300 Hz and add an approximately B&K compensation to the former. Looks like that'll bring things closer.

    Edit: And then, find some headphones to compare with some of the compensated flat plate measurements (cFPC) here:

    https://github.com/superbestaudiofriends/headphone-measurements-frequency-response

    Edit 2: In red.
     
    Last edited: Jan 27, 2022
  19. Philimon

    Philimon Friend

    Friend
    Joined:
    May 6, 2016
    Likes Received:
    1,242
    Trophy Points:
    113
    Location:
    Portland, OR
    [​IMG]

    fpc test2 vs test1 vs EARS.jpg

    How would I go about that?

    edit: You’re saying I should alter my EARS compensation to match my fpc measurements (by applying a B&K curve to EARS)?

    My fpc and EARS would be okay if not perfectly aligned. I mostly want to use the fpc for distortion and csd measurements.
     
    Last edited: Jan 28, 2022
  20. Biodegraded

    Biodegraded Friend

    Friend
    Joined:
    May 28, 2017
    Likes Received:
    6,055
    Trophy Points:
    113
    Location:
    Vancouver BC
    Export the mic cal file and the B&K curve I sent you a while back (if you still have it) as text files from REW with the same settings. Then add them together in Excel, import the result into REW, and use that as the mic cal file.

    Or send me the mic cal file and I'll do it for you :)
     

Share This Page