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Headphone CSD waterfall plots

Discussion in 'Headphones (full-size)' started by purrin, Aug 13, 2011.
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  1. purrin


    LFFT50RPL.txt.bmp   LFFT50RPR.txt.jpg
  2. tdockweiler

    RX300 pads? For me, those sounded as good as the M30/V6 pads (if not better) and I didn't notice any loss of bass, but it's possible. I'd be curious if the stock pads gave better measurements, but maybe not.
    Not sure how the bass of the HD-558 compares to the 598, but the DJ100's bass (with my setup) makes my 598 seem almost bass light in comparison. Love the bass on the DJ100 with good pads (and a good seal). I've also never had a headphone's sound change so much with pad swaps as I have with the DJ100. Sometimes it's hard to figure out why this is. It seems like the more open the pads are, the more I get an impression of more treble. Very strange.
    I bet every single pad would probably measure completely different with this headphone [​IMG]
  3. Reticuli2

    Right, I get that insufficient damping will cause oscillations and ringing, but assuming two headphones have proportionally (to each's initial impulse breadth) the same amount of oscillation and ringing and seems to take about the same amount of time to settle, is it possible for one of their initial impulses to be too high (even cleanly in the correct direction... up, obviously) than optimal?  Is bigger always better, or are we talking here just about frequency response being responsible for how big or little the initial impulse actually shows up as and is therefore unimportant; i.e., it's the proportion of oscillation and time to settle that are important.  ???  In other words, I get that we should be looking at how clean the initial impulse is, how much oscillation there is, and the importance of time to settle.  But how do you know how tall the initial impulse should be and is there such a thing as overshoot on the initial impulse and is that a bad thing, even if oscillation does not increase?  Say, comparing the Q701 & HD800 to the T1 & DT880, which have much taller impulses on Tyll's measurements.  And then at the other extreme you have very (seemingly) damped impulses like the Shure 535.

  4. purrin
    You can overlay the measured square wave or step response to the original signal and compare. This is the only way you will know how much you are off. In almost all most cases, you are going to see overshoot with the initial rise. Overshoot is not necessarily bad. It's a limitation of mechanical devices trying to simulate what is not found in nature. This is what I'm getting at when I say I'm wary of square waves that look too nice.

    Yes, it's called an HE-6. Sounds etched as hell and I don't even need to look at impulse response to know that. So you know what I mean when I say it's subjective?
    All other aspects of the step response don't interest me because either I haven't been able to correlate them with with any other sonic properties, or there are better measurements out there. Step responses only interest me when I'm designing a crossover and trying to align the phase (that's another long story.) For single driver headphones, square waves are only a passing curiosity and last in my box of tools to use.
  5. purrin


    Just to give everyone some background, and Arnaud hinted at this too: I employ an open measurement method that seeks to take the head-cup / enclosure out of the equation as much as possible. To this end, I am only partially successful (the only way to be completely successful would be to remove the driver, as I had done with the "liberated SR80i driver" measurement.) So we can still see some enclosure effects on my data.
    So for this test, I decided to use another method here where I could achieve a tight seal on the DJ100. This tight seal measurement method gives us more accurate bass FR response for headphones that are more closed or have big pads. The downside to this method is that tends to record wierd cancellation nodes and resonance peaks (that our ears and brain are able to filter.) But anyways, here it is with some comparisons:

    DJ100 Tight Seal Measurement Method

    Normalized with original measurement. You can see the effects of the cups emphasized and some funky peaks and cancellation nodes in the treble.

    DJ100 open method measurement


    HD558 / 598mod

    For reference.
  6. purrin

    Darth Beyer V3

    Bass heads take note. Mainly for historical interest. I don't think these are as popular as they used to be.
    One bass port open, one closed with electrical tape. It doesn't matter much because I am using my standard measurement technique to minimize effect of head-cups.
    Here is with a tight seal measurement for only up to 1ms. The intent here is to show FR @ t=0. Both bass ports are open.
  7. Reticuli2
    So I assume you'd only know how high the initial impulse should be by seeing the raw electrical signal, right?  And I assume the Koss is supposed to be inverted like that?
  8. purrin
    Yup, we should be able to get a very good approximation from knowing the electrical output, sensitivity of the drivers, and sensitivity of the measurement microphone. The impulse response of the Koss is inverted. It's possible the amps I used invert the signal (this is not uncommon), or I was just retarded and clicked the invert signal toggle switch on the measurement software.
  9. purrin
    Yup, we should be able to get a very good approximation from knowing the electrical output, sensitivity of the driver, and sensitivity of the measurement microphone. The impulse response of the Koss is inverted. It's possible the amps I used invert the signal (this is not uncommon), or I was just retarded and clicked the invert signal toggle switch on the measurement software.

    Whether you can hear inverted signals is a matter of debate. My DAC and Joe Grado HP1000/HP1s have toggles to invert the signal.
  10. 200poundsofamp


    I'd love to see this too. If anyone has a 940 I can send an 840 in.
  11. ohmyheadfi
    Please excuse my ignorance, but can someone explain or point to me a good link on how to read these plots? I'm interested in furthering my knowledge of understanding audio measurements so I can better make informed choices on head phones, being a relative newcomer to quality headphones (at one time, I too used to think Bose was king).
  12. purrin


  13. purrin


    Non-linear Distortion

    Here are a few non linear distortion measurements. My place is fairly noisy, so the noise floor, especially in the bass is high. There is natural spike at 120Hz - probably computer PS noise. There appears to another at 150Hz too (I have no idea about that one, maybe the CPU bus?) The 0db point is 95dbSPL on the graphs. These graphs will show both HD and IMD.

    HD800 and HP1000 at 50Hz

    HD80050hz.jpg   HP100050hz.jpg
    • Note the 120Hz spike - that's part of the environment.
    • You can see the HD800 has it's 2nd harmonic (100Hz) about 45db down, and it's 3rd harmonic (150Hz) 35db down from the fundamental. The 3rd harmonic is definitely hearable. There is a little spike at the 5th harmonic too (250Hz). Overall extremely clean with a light touch of odd order harmonics.
    • The HP1000 has a large 2nd harmonic contribution at only 20db down. This probably has a large part of the HP1000s reinforced, organic sounding bass. It's 3rd harmonic is way way down.

    HD800 and HP1000 at 200Hz and 2200Hz (two tones)

    HD800200-2200hz.jpg   HP1000200-2200hz.jpg
    • The HD800 is cleaner than the HP1000 with the exception of the small 3d harmonic (600Hz) spike from the 200Hz tone.
    • The HP1000 is ~10db higher than the HD800 on the 2nd order distortion from the two test tones.
    • The HP1000 has more IMD intermodulation distortion. This is the more nasty stuff. You see higher more 10+db higher peaks at 2000Hz (2200-200), and 2400Hz (2200+220) including their 2nd order harmonics (4000Hz and 4800Hz).
  14. purrin

    ESP950 50Hz

    2nd harmonic is 25db down, a little bit better than HP1000, but not as good as HD800. The 3rd harmonic is better than HD800 and almost as good as HP1000.

    ESP950 200+2200Hz Tones

    Very similar to HD800. Higher noise floor - could be amp (SRM323) differences. Very clean.
  15. purrin

    HP1000, H800, ESP950 non-linear distortion graphs - 3500Hz and 3850Hz tones

    HP10003500.jpg   HD8003500.jpg   ESP9503500.jpg    
    HP1000 < HD800 ~ ESP950. It's all very close though. Much cleaner than speaker drivers.
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