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Effects of damping factor on planar magnetics/orthodynamics ? - Page 4

post #46 of 55

My Master-6 with 1 ohm output impedance drives the HD800's exceedingly well  :biggrin:

post #47 of 55
This is great, I am getting a few new cans, but I only have Schiit Vali to drive them. So I was worried with Vali's high output impedance. I guess it will be fine. Great thnx.
Edited by namhkim - 3/11/15 at 9:57am
post #48 of 55

So far, HE400 and HE400i has been really good without any ringing noise with Vali. But, some 60~70 Ohms dynamic coil headphones were rinigng... I guess orthos' impedance is really different from conventional coiled drivers' impedance..

post #49 of 55

so far the orthodynamics I've seen Z plots for look really flat - nearly pure resistors - which means they essentially shouldn't care about amplifier resistive output - its just a flat amplitude divider ratio without frequency response effects


Edited by jcx - 3/31/15 at 12:09pm
post #50 of 55
Quote:
Originally Posted by namhkim View Post

So far, HE400 and HE400i has been really good without any ringing noise with Vali. But, some 60~70 Ohms dynamic coil headphones were rinigng... I guess orthos' impedance is really different from conventional coiled drivers' impedance..

Yeah, they don't have that resonance in the low end like dynamics. As jcx said, or those are virtually purely resistive.

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post #51 of 55

Just a tidbit of physics I feel like mentioning, and maybe you guys already know this, but anyway here goes.  The Yamaha manual stated "... absolutely no impedance change for any frequency..." and "there is also no inductance..."   It turns out the former is actually a direct result of the latter.  Any coil of wire has inductance, and with that comes a concept called reactance.  Reactance is essentially a variable resistance.  In an inductor,  the reactance is directly proportional to the frequency played through it.  The concept of inductance essentially only applies to dynamic headphones, as inductance is a property of coils.  So basically, in a dynamic headphone, the overall impedance (which takes into account the reactance of the voice coil) will be higher in the highs and lower in the lows. I believe this means that in reality the highs would be attenuated (albeit a small amount probably) and the lows would be kicked up in amplitude a little.  Again, because this only really applies to coils, planar magnetic headphones should have essentially no inductance --> no reactance --> and finally, an essentially flat impedance.  

post #52 of 55

the planar conductor does have low inductance - but there is still mass-spring resonance in any driver which is reflected to the electrical terminals by the electro-acoustic properties of the "motor" and mass and suspension of moving parts

 

for electrodynamics there should still be the mass-spring resonance of the diaphragm but it isn't as easily visible at the electrical terminals in part because of the poor efficiency of most Orthos as electric "motors"

 

and the diaphragm's resonant peak can also well damped in the mechanical-acoustic domain by the magnet structure and intentional added flow/acoustic resistive damping material

post #53 of 55

Great answer, very concise and simple!

 

By any chance do you know roughly in which range of frequency can be the mechanical resonance of a planar magnetic driver like the audeze LCD? As you pointed out since such a driver is like an harmonic oscillator (mass-spring system) then there must be an associated natural frequency (resonance frequency). I was wondering if the resonance was well outside the audible range, being the thin film diaphragm very light.

 

Quote:
Originally Posted by jcx View Post
 

the planar conductor does have low inductance - but there is still mass-spring resonance in any driver which is reflected to the electrical terminals by the electro-acoustic properties of the "motor" and mass and suspension of moving parts

 

for electrodynamics there should still be the mass-spring resonance of the diaphragm but it isn't as easily visible at the electrical terminals in part because of the poor efficiency of most Orthos as electric "motors"

 

and the diaphragm's resonant peak can also well damped in the mechanical-acoustic domain by the magnet structure and intentional added flow/acoustic resistive damping material

post #54 of 55

I'd still guess the underlying mechanical diaphragm drumhead resonance was low bass but I don't know, possibly it could be higher with circumaural headphones only driving a smallish mostly sealed cavity

 

 

couldn't see a low bump even in the couple of high res impedance plots at http://www.innerfidelity.com/headphone-data-sheet-downloads that I looked at - maybe looking at more would give a hint


Edited by jcx - 4/13/15 at 7:15pm
post #55 of 55

I always assumed that it was outside of the measured range. but now you make me wonder ^_^ .

the mechanical damping should be very strong on a planar, as it's only the film stretched. so maybe it's just not visible because it follows an overdamped behavior and doesn't really have much time to oscillate and even less to keep a noticeable amplitude?

anyway the more damped, the slower the frequency if I remember my stuff. so I would tend to agree with jcx that it could be a relatively low frequency.

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