[fewtch]

OK... I wanted to test this for myself, using my ears and nothing else. Since I use a high end PC sound card as a source, this was easy.

What I did was generate a sweep tone (pure sine wave) from 0Hz/DC to 24 KHz, 24 seconds long. This gave me an idea of what frequency was what, based on the time display in the program I used (Cool Edit Pro / Adobe Audition). My headphones are the Sennheiser HD-580 with stock cable, my amp is a Creek OBH-11 with an upgraded/linear regulated power supply.

I performed the test first with another, cheaper set of headphones as a control (just to make sure it wasn't the amp or soundcard doing something to the frequencies, or I generated the tone sweep incorrectly), then I listened to the sweep tone multiple times at different volume levels through the Senn HD-580.

Sorry to report, the HD-580 is indeed recessed in upper midrange (7 KHz - 10 KHz). In fact, it's so recessed that around 8.5 KHz the drivers basically stop responding altogether -- i.e. there's almost no sound coming from the headphones. It climbs back up soon afterward (by 10 KHz it's responding fine again) but the dip in upper midrange is drastic and unmistakable. The response sounds mostly flat throughout the rest of the spectrum, but varies wildly between that range of around 7 Khz to 10 KHz.

I'm kind of bummed out, but this may be intentional on Sennheiser's part in order to produce the kind of EQ that sounds diffused and airy, rather than inside one's head. I wonder if a cable upgrade might not help with that midrange issue...

 

[Wilson M.]

Actually, here are the usual definitions for the various "ranges":

Bass: 20Hz - 140 Hz
Mid-Bass: 140 Hz - 400 Hz
Midrange: 400 Hz - 2.6 KHz
Upper Midrange: 2.6 KHz - 5.2 KHz
Treble: 5.2 KHz - 12 KHz
Upper Treble: 12 KHz - 20 KHz

Of course, sound can go above that. For example, an orchestral cymbal "kiss" actually has most of its spectral energy at 40 KHz.

What you are hearing in the 7-10 KHz is traditionally in the treble range. Although most instruments are "in" the midrange and upper midrange, their higher order harmonics typically reside in the treble region.

 

[JaZZ]

I've always stated that the HD 580/600 has no recessed midrange, but a treble dip around 8 kHz instead (also to be seen in the graphs). Well, 7-10 kHz is the center of the treble, certainly not upper midrange, which would be between 2 and 5 kHz.

I don't think someone would want to design a headphone with such a flaw intentionally - such things sometimes are out of control even for experienced developers. It's not even a serious flaw, obviously, but one that still ensures the headphone a place in the highest leagues.

 

[Wilson M.]

If most instruments have higher order harmonics in that treble dip region then is it possible that those instruments might sound subdued despite having the fundamental harmonics in the midrange/upper midrange?

Is it this "subdued" nature that is what people attribute to being the "recessed" midrange?

(I don't know the answer so that's why I'm asking.)

 

[fewtch]

Quote:

Originally posted by Wilson M. Actually, here are the usual definitions for the various "ranges": Bass: 20Hz - 140 Hz Mid-Bass: 140 Hz - 400 Hz Midrange: 400 Hz - 2.6 KHz Upper Midrange: 2.6 KHz - 5.2 KHz Treble: 5.2 KHz - 12 KHz Upper Treble: 12 KHz - 20 KHz Of course, sound can go above that. For example, an orchestral cymbal "kiss" actually has most of its spectral energy at 40 KHz. What you are hearing in the 7-10 KHz is traditionally in the treble range. Although most instruments are "in" the midrange and upper midrange, their higher order harmonics typically reside in the treble region.

Thanks Wilson, I actually saved that in a text file for future reference.

The dip is in the treble range then... and it sounds (to me) audibly more pronounced than Headroom's graphs would suggest. At a "normal" listening volume, the sound practically disappears at about 8.5 KHz. There's also a perceived shift in "headstage" between about 7 and 10 KHz, i.e. the sound seems to shift from left to right and back to left again although neither the volume nor the stereo balance of the sweep tone changes. The drivers aren't responding linearly or properly at all in that frequency range.

I've now tested two different headphones in addition (Denon AH-D950 and AH-D750) and although they have their issues too, it's at different frequencies and nowhere near as drastic as the HD-580. That's what was making me think this could be a "feature" and not a "bug." Perhaps it's a design compromise in order to make the rest of the spectrum flatter and smoother.

Edit -- I posted this test simultaneously on another board, and got a response I feel is worth noting:

"These frequencies ranges are the ones where human hearing varies the most, according to Fletcher-Mundson Curves (highest slope between 5 and 8 kHz)..."

 

[sacd lover]

The frequency ranges are doubled or halved to produce an octave. Our hearing supposedly ranges approximately 10 octaves from 20 hz to 20,000 hz. I have always saw the ranges described this way:

< 80 hz low bass
80-160 mid bass
160-320 upper bass
312-625 lower midrange
625-1250hz midrange
1250-2500hz upper midrange
2500hz-5khz mid treble
5khz-10khz mid treble
10-20khz upper treble

If you do this from the bottom up you come up with slightly different ranges but similar: This is the way I have generally seen the different ranges. I believe I read this years ago in Stereophille magazine.

20-40hz low bass
40-80hz mid bass
80-160hz upper bass
160-320hz lower mids
320-640hz midrange
640-1280hz upper midrange
1280-2560hz low treble
2560-5120hz mid treble
5120hz- up upper treble

Maybe there is a music major who could clarify this?

 

[MusicLover]

Besides what has already been stated, I have noticed a recession in the midrange from 1khz to about 2.3khz. I have also noticed slight recession at around 5khz. Has anyone else noticed this?

 

[fewtch]

Quote:

Originally posted by MusicLover Besides what has already been stated, I have noticed a recession in the midrange from 1khz to about 2.3khz. I have also noticed slight recession at around 5khz. Has anyone else noticed this?

Another person's observations (from another board I posted this on which included a link to a slightly different frequency sweep file) -- note that seconds = KHz with this one:

HD-600 here.

A bit unstable between 1 and 2 s (fast volume drop outs, more in the right channel).
Smooth drop out between 5 and 6
Varies in volume and balance between 7 and 8 (drop outs in both channels, more on the right one).

Looks like this guy agrees with you.

http://www.hydrogenaudio.org/index.php?showtopic=13499

 

[NathanJM]

Quote:

Originally posted by fewtch Another person's observations (from another board I posted this on which included a link to a slightly different frequency sweep file) -- note that seconds = KHz with this one: HD-600 here. A bit unstable between 1 and 2 s (fast volume drop outs, more in the right channel). Smooth drop out between 5 and 6 Varies in volume and balance between 7 and 8 (drop outs in both channels, more on the right one). Looks like this guy agrees with you. http://www.hydrogenaudio.org/index.php?showtopic=13499

After listening to the FLAC file he posted, I can hear the one between 7 and 8, but it is hard to tell how extreme it is as a result of a simultaneous change in my attention due to a decreasing sweep also occuring in that time span. From what I can tell, the drop off is brief. It is also less severe, imo, (but still present) when i remove the foam pads.

i dont hear the ones at 1-2 and 5-6.

might be relevent to note that i am listening to my 580s with the Equinox cable, so that may explain my inability to notice the latter 2. I no longer have my stock cable to verify this, though, so i can't really draw any conclusion about that.

 

[Geek]

I'm going to generate a sine sweep with cooledit to test this out tonight. I've always thought the HD600s were "natural" sounding with a neutral liquid midrange; if I find the same evidence in a sine sweep then this will confirm what I thought I heard.

8khz or so is indeed in the treble range.

Cheers,
Geek

 

[darth nut]

<In fact, it's so recessed that around 8.5 KHz the drivers basically stop responding altogether -- i.e. there's almost no sound coming from the headphones.>

Almost all headphones have to do that. At 8-9kHz there is a resonance frequency intrinsically caused by the coupling between earcup and ears. The dip at 8.5 couteracts the resonance.

Check out j-curve's curves.

Diffuse field equalised headphones should not have a flat FR, or else the tonal balance of such headphones would resemble a pair of loudspeakers existing in an anechoic chamber. (Voicing a headphone for diffuse field equlisation would not however make the headphone imitate the time-delay reflection characrteristics of a pair of loudspeakers existing in a normal room. Time-delay and altered FR are two separate things.)

 

[Geek]

WOW!

I did the test just a few seconds ago. I generated a pure 20hz-20khz sine sweep that lasts two minutes in length.

At 0:30 the frequency is 5khz.
At 0:45 the frequency is ~7.5khz.
At 1:00 the frequency is 10khz.

And so on.

Anyways, I indeed hear a sort of "recession" at about 8khz! It is very narrow, lasting from about 0:43 to 0:48.

At precisely 0:47, the sound sweeps from center to dead left channel.

In order to figure out if this was due to my hearing, I made the results redundant by switching channels.

The exact same thing happens: at 0:47, which is about 8khz, the sound goes all the way to the left ear - regardless of if it's the left or right channel.

There IS a recession, but it IS in the right place: the 8khz drop is part of diffuse-field equalization and a lot of headphones, even supposedly aggressive ones, have that.

Cheers,
Geek

 

[pinkchry]

Um, if the sound goes to your left ear regardless of channel, doesn't it mean your ears are at fault?

 

[fewtch]

Thanks... this clears up a lot for me (and I hope nobody is mislead by my previous speculation on why this happens... I won't change the posts though, as I figure if anyone's interested enough in the topic they'll probably read all the way through it).

 

[psyco1]

Quote:

Originally posted by pinkchry Um, if the sound goes to your left ear regardless of channel, doesn't it mean your ears are at fault?

I take it as the sound level at 47sec dips below his right ear's ability to hear it.