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CSDs How Do I Read These?

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Marvey:
Cumulative spectral decay (CSD) or waterfall plots measure energy content over time across all frequencies based on a "sound burst" that excites all frequencies. They are sort of like a FR over time (technically not really as they measure energy throughout the band in successively smaller windows over time.) These plots are a good tool to "see" driver ringing or resonances (seen as ridges), which typically sounds bad (piercing, glare, shoutyness, etc.); and how fast and cleanly the driver decays (speed and extraction of low level information.)

For a perfect or near-perfect response, the decay should be immediate. We first see a wall (meaning all frequencies are excited) at the beginning. The next few fractions of a millisecond, the wall collapses into silence (meaning the driver is no longer vibrating or sound waves are no longer bouncing around inside the headphone enclosures.) The back wall at time = 0 is basically an uncompensated frequency response. Successive plots over time move toward us.

OLDER LINK / Types of driver ringing: http://www.changstar.com/index.php/topic,71.msg219.html#msg219

Marvey:
Harmonic distortion notes:


Taken with headphones on sealed plate. White noise at 90db SPL A-weighted.


D2 = 2nd harmonic
D3 = 3rd harmonic


etc.

rhythmdevils:
There is also some good information on reading CSD's in the beginning of this thread

http://www.head-fi.org/t/580283/lcd3-measurements#post_7891455

transparent201:
Hello Purrin.
Have you ever thought of IMD measurements on headphones? I think that IMD is more representative because real sounds are complex. Also, what is your opinion on multitone IMD distortion test combined with a psychoacoustic model to determine what is audible?
See here: http://www.gedlee.com/downloads/Distortion_AES_II.pdf

takato14:

--- Quote from: transparent201 on September 09, 2013, 05:38:40 PM ---Hello Purrin.
Have you ever thought of IMD measurements on headphones? I think that IMD is more representative because real sounds are complex. Also, what is your opinion on multitone IMD distortion test combined with a psychoacoustic model to determine what is audible?
See here: http://www.gedlee.com/downloads/Distortion_AES_II.pdf

--- End quote ---
This actually might be a very useful measurement to take, if possible

I've noticed a surprising sense of clarity and cleanliness from large, thick mylar diaphragm that doesn't flex while in use, despite the slow attack/decay caused from the excessive weight of said diaphragm

I suspect an absence of modal problems and/or IMD to be the cause of this

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