Preliminary headphone vibration measurements (HD600 vs. HD800)

First of all, take these with a HUGE grain of salt. I measured these last night before going to bed. This is something that I wanted to do for a longer time.

Read this if you haven't already:
A passing idea on vibration analysis.....


I used one of my WM61-A mics and basically made sure that it got good contact on the surface I was
measuring at. I would've preferred to use something similar to blu-tack but this green stuff was all I had.

Obviously an accelerometer would've been preferred for this and I'm not sure if these measurements are even worth looking at without one.


For now, some measurements of my HD600 and HD800. Both were driven to approximately 80-85db at 500Hz. Currently I don't have the screws that hold the driver in place in my HD800. I am using felt rings instead of the stock metal rings. I will later find a way to screw the felt in.

Both headphones were placed on my open cell foam (I believe) coupler. I tried it without the coupler and the results looked different. I also tried it on my head and they were way too noisy. I think the coupler results were comparable to my head.
These plots go all the way down to <10Hz. I think this makes sense for these plots (but then again maybe not):


On the back of the headphone, on the shiny plastic of the driver enclosure - darker color is directly on driver enclosure, lighter color is on the piece of plastic where the cables go

Inside the earcup - see below

outer ring: The ring that says "High Definition Driver ...",
connector area: Part of the outer plastic, where the cables from connector to driver are)

HD800: Top of the headband - the part with the S/N
HD600: Side of the headband

HD800: Side of the headband
HD600: Top of the headband

We should technically be looking at the CSDs or spectrograms but for now the FR will do. A peak in the FR is almost certainly also a resonance.

On the HD600 it looks like there are some driver enclosure resonances from 1-3kHz. This even carries on to the plastic part of the headband. The metal part of the headband measured much better.

On the HD800 it looks like we might have some 300Hz features. I mainly saw these when I attached the mic to the black leona frame. 300Hz is much lower in frequency than the HD600s 1-3kHz but these aren't directly comparable. I wish I measured the sides of the HD600 enclosure. I will probably do that at a later time.


I would really not go all nwavguy on these measurements. Really, before we can say anything (how they relate to the sound) I would have to measure many more headphones and revise my methodology. Ideally I would use an accelerometer and have the headphones sitting on a dummy head. I was mainly interested in seeing if Senn's material choices and headband design would bring measurable improvements and it certainly looks like they did.

I would also like to measure the effects of dynamat or other modifications like this.


What do you think of this? Is something like this even worth pursuing? What would a better measurement setup for measuring enclosure vibrations look like?. Should we test one area of a headphone at multiple volumes or do you think that this would be pointless?

EDIT: Updated pics with descriptions on where the microphone was placed. Again - this discussion is more about the general topic than these measurements specifically.

 

Can you explain the trapezoid by picture? I'm having a hard time figuring out what it is from OJneg's description.

 

Here you go, I only called it trapezoid area because that is what the Anax mod piece was called (even if it wasn't really trapezoid shaped with Anax 2.0).

(I placed the mic where the red circle is. (My HD800 is in a colorware white color) Here you can also see the felt ring around the driver and the resonator (and the fact that I cut out the middle part of the driver dust cover).)

I should really add comments on where all the areas are,

EDIT: Since the mic was in the earcup for that measurement, I also think that there is some sound leaking into the microphone. I certainly had this problem when I tried to measure in other areas in the cup, closer to the driver. I also didn't place the HD800 on the coupler for that measurement. The other one I have uploaded (outer ring - that's the ring that says "High Definition Driver 300 Ω") does seem to show the same thing.

 

Would be interesting to see what kinda measurable impact (if any) mods would have on this, like dynamat on the HD6x0 diver lollipop etc.

 

Yes, exactly.
I am actually planning on measuring this. I will revise my methods slightly (I have something similar to blu-tack now), then remeasure everything and buy some dynamat. This is actually why I wanted to measure this, to see if the dynamat mods show measureable improvements (I think @Hands said it cleaned up the CSDs a bit, would be interesting to see that).

 

Do you remember which frequency range it affected?

 

Has anyone tried using a contact mic on headphones?

 

Per the July minimeet thread, it appears you've now dampened your HD600. Wanted to see if you had performed any of these measurements yet? Might be a useful supplement to the measurements here: http://www.superbestaudiofriends.or...d650-dynamat-mods-proof-that-its-not-bs.2098/

 

I didn't try these kind of measurements on my HD600. I'm not sure if the measurements in my OP were any good. Could also be just driver sound bleeding through the material I used for coupling (though I doubt 20db differences for two different headphones). I tried the measurements @Marvey posted but I didn't see any change in noise floor with neither the stock nor the modded HD600 on my rig. Maybe I should reverify and crank things up. I think for these measurements one would need a real accelerometer.