[Paul Blythe]

Hi, I've had my Sennheiser HD-650's for a couple of months and have clocked up about 150hrs of use; roughly 30 hours with my Oppo BDP-83 / Denon AVR-2310 set-up and 120 hours with an Asus Xonar Essence STX...
 
I ran a 24bit/92kHz 20-20kHz Stereo frequency sweep off a AIX Records Audo Calibration Disc (Blu-ray) and heard a dead spot in the treble area; the test tone quickly fades to nothing then back up again ... I found some mp3 left/right 20-20kHz sweeps over the Internet for playback with my STX card using foobar2000; Again the dead spot is there.
 
With the foobar spectrum visualization I know this dead spot occurs within the 8kHz range in both left & right channels; dropping at just over 8kHz and back up again just bellow 9kHz [8.3 to 8.7kHz area] ... Are my HD-650's faulty? Is this inherent to the 650's?
 
Thanks ... Paul

 

[jupitreas]

As you can see from the graph below, the HD650 does have a dip around that frequency, but it should not be anything as drastic as you describe.

Before you send your HD650 in for replacement, you should probably ask a friend to confirm this finding.

 

[goobags]

The HD650 does have a bit of a lack of treble and thats just the phone - I wouldn't worry that there is a small gap in the frequency response. Remember that headphones are designed to listen to music.
 
Guy

 

[Paul Blythe]

Thanks for the quick replies; even knowing that the gap is there hasn't detracted from my enjoyment of listening to music with the HD-650's and it's not something that I've noticed under normal listening ... as suggested I'll ask a friend to confirm what I'm hearing, or not.

 

[Coolsax]

i'm not sure there should be a gap at 8,000, if each of the hashes actually represent 1Khz then the dip is actually at its lowest at around 3500 prior to completely dropping off after 9K, while going up in the 8-9Khz range.  now if i'm reading the graph wrong let me know...

 

[Paul Blythe]

Listened again to the sweeps at a much higher volume this time and there is a definite gap. The STX pci-e audio card has a bright signature so the upper mid's and treble sound stronger, but I can here the slight drop then a fast fade to nothing and back up again for the last little bit.
 
Shame I don't have a way of taking measurements, it's these little mysteries that add an extra touch of enjoyment to the hobby...

 

[olor1n]

Do you have other headphones or speakers to run the same tests?

 

[Paul Blythe]

Only speakers ... I moved the computer into the front room so I could connect the STX card to the Denon amp. Playing the 20 -20kHz sweep through the front speakers I get an unbroken tone all the way through, plug the 650's in and the gap is there.
 
It's a definite dead spot rather than a dip in output from the drivers.
 
I'll query Sennheiser over it and see what they recommend.