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Objective: a more well-rounded headphone - Page 3

post #31 of 47
Quote:
Originally posted by mr_slacker

And i think a closed headphone "should" have more bass than a open one (if they are based on the same design ofcourse).
What is the technical foundation of the above statement?
An open back circumaural can is akin to an infinite baffle spkr and potentially capable of much deeper and more natural bass response than a closed back design which would be akin to an "acoustic suspension" speaker which is an aproximation of an infinite baffle in a smaller box.
Cheers!
post #32 of 47
Quote:
And finally: to me, impactful and slamming bass response seems to be less a matter of frequency response than of phase response. Phase non-linearities are said to be far more audible at lower freqeuncies - the brain has less cycles to compute. And then there is THD, of course, what good is bass response at -0dB if 20dB of the 90 dB spl is harmonic distortion?
Phase response and non-linearities are not factors here and harmonic distortion is very dificult to hear at low frequencies.
post #33 of 47
Those aren't factors? You aren't saying all headphones sound the same, are you?

This is was John Murphy of True Audio has to say about phase response and perceived fastness of bass reproduction. What do you think about it?
post #34 of 47
Tom,
While the comments are valid in the loudspeaker world, you'll find that they're just not a significant factor here in the headphone world.

We're not dealing with room interaction, crossovers, cabinet tuning, conversion of rear wave radiation to phase allignment with front wave, or relative driver mass in headphones, much less distances being measured in mm rather than feet between ear and driver.

So while I agree with John Murphy's points in the speaker world, again, they're not factors we typically deal with in the headphone world.
post #35 of 47
kwkarth, I understand your point. But what's your theory then? Why is there a perceivable difference in bass reproduction among headphones?
post #36 of 47
Quote:
Originally posted by mr_slacker
And i think a closed headphone "should" have more bass than a open one (if they are based on the same design ofcourse).
The problem is, they could never possibly be based on the same design.
post #37 of 47
Quote:
Originally posted by Tomcat
kwkarth, I understand your point. But what's your theory then? Why is there a perceivable difference in bass reproduction among headphones?
Tom,
There are lots of factors that affect bass response in a headphone system.
Among them:
  • driver compliance / driver loading
  • driver size
  • driver mass
  • driver resonant frequency and magnitude
  • voice coil design
  • magnet structure design
  • distance from eardrum to diaphragm
  • completely open vs circumaural vs supra-aural vs canal
All of the above factors and more interact to affect bass response, both in terms of amplitude and quality.
post #38 of 47
Kevin,
those are design parameters, not performance parameters. Isn't our question this: How do we measure bass performance in headphones?

I am not a big advocate of relying on measurements. I am convinced we hear and perceive a lot more than can be described through measurements and scientific models of human hearing. All I tried to point out was that there is very likely more to bass accuarcy than what quantitative amplitude vs. frequency measurements can tell us. If we throw out phase linearity and THD, how do we measure bass quality?
post #39 of 47
Tom,
I certainly can't dissagree with you there. Sorry for missing your initial point. I have to say though that phase allignment and related problems such as are common in the speaker world pretty much do not exist in the headphone world and bass response characteristics of headphone systems are pretty much dictated by the physical characteristics that I mentioned earlier.

Much of what we perceive as bass "quickness" is actually midband response which is time alligned with actual low bass information. So if your headphone has the physical characteristics which allow it to reproduce low frequency information AND has no significant dip in the midband and up through 8k or so, AND whose magnetic system has control of the diaphragm so as to minimise overshoot (which would muddy the sound) then it would be perceived to have good quick bass. If there is a suck out in the portion of the spectrum where you hear transient attacks, the bass will not sound as "quick" even though the amplitude of the bass information itself were more than adequate.

Assuming that one has "control" of the mechanical system of the driver, the main component contributing to quality of perceived bass sound in a headphone system is indeed frequency response. As noted though, that frequency response requirement is not confined to bass frequencies alone even though we're talking about bass quality.

Phase problems come into play in high frequency reproduction in a headphone system. When I say "system" I am referring to the interplay between physical driver and the human ear, pinna, ear canal, etc.

When judging bass performance alone, THD under 1% is inaudible to most and under 5%, inaudible to many, under 10% inaudible to more than a few.
post #40 of 47
I remember seeing a THD vs. frequency graph printed on the package of the Philips HP 890. To my ears, they have very respectable bass reproduction, and their THD level rose sharply the lower the frequency. I recall something like 10 percent or more at 20 Hz.

There are two possible conclusions: either they have quite tight and slamming bass in spite of their rather high THD - as you would suggest, kwkarth - or their bass quality is well above average because most other headphones have THD figures that are a lot worse. I guess we have simply insufficient data to decide this either way.
post #41 of 47
As frequencies decrease, our sensitivity to THD goes down. I think 10% HD is quite high in an absolute sense, but at 20Hz, that's probably not too bad at high SPL's.
post #42 of 47

While we're on the subject of the DT770's...

Tomcat,

I received my DT770's and Porta Corda kit from Jan yesterday. I don't have the PC assembled yet, so I'm just running them out of my Gemini PS-676 Pro2 mixer, because they can actually push headphones quite well. It's the best thing I have I'm trying to give them as much burn-in time as possible (they listened to my collection of The Orb, now they are enjoying a playlist full of Orbital). Four words: I LOVE THESE CANS!

How do they sound best to you...at 0 ohms, or with a 120-ohm adapter? Any recommendations? I'm not sure how I feel about the sound between the two choices...I did some brief A/B comparisons last night and it seemed like the adapter generally subdued the music. But, I didn't get into it, only about 3 or so minutes of swapping back and forth. Any comments?
post #43 of 47
Quote:
Originally posted by kwkarth
...at 20Hz, that's probably not too bad at high SPL's.
And even less important at low SPL's.
post #44 of 47
punosion,
it's great that you are happy about your choice!

I don't know the Porta Corda and thus can't help about the resistor question. I have never tried introducing a resistor in the signal path. If one is partial to triode amps, one has the opposite problem: getting one with a low output impedance. I understand Jan introduced the 120 Ohm option to tailor his amp to rather bright headphones like the DT931 and 831 and to bring their treble down. Why don't you just try what works best with your 770s and tell us about your results?
post #45 of 47
Tomcat,

Well, just based on a 3-minute A/B comparison, it would appear that I would never use a 120-ohm adapter. It just makes it sound too awkward...like something got washed out. But, I was just looking for someone else's input to see if they kinda heard the same thing. I guess I really don't need to worry about the 120-ohm adapter if I am still running them out of a PCDP at work. I haven't put together the PC yet, so even a PC with a 120-ohm adapter would sound better than these things out of just a PCDP
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