[germanium]

Got my GL600's today and they sound phenominally good except for a kind of nasty peak in the upper midrange-presence area. Otherwise these sound great. In order to address the peak I tried to increase the damping but that didn't work. It made vocals sound thin. I though about removing the paper from back of driver but that's there to address the drum resonance of the driver and that may cause the lower frequency vocals to sound thick or cause bass to interfere with vocal range. I ultimately decided to remove foam that was directly behind driver, just the foam directly behind the driver openings. All the other foam was retained that goes around the driver. This did help some & did not cause issue with vocal range or bass interference.

This is what it looks like.

Not too bad for someone who had stroke and very shaky hands

 

[germanium]

After considerable listening & consulting a friend of mine that owns a studio & asked about the characteristics of the mikes used in the recordings he made. I found that my modifications to the headphones took them the wrong direction as there was way to much energy in the 1-2KHz range due to lack of damping. There was already a hot spot in the sound spectrum here when stock so I made it worse by removing the foam. It did seam to make the sound more consistent but it was more consistently wrong & on some music made the headphones unlistenable beyond even very modest output volumes.

I since reestablished the foam center & actually added some thin cloth that I cut from an old t shirt & a piece from an old sweat shirt for some added damping between the foam & back of driver & added some foam between the front grill cloth & the driver as well for a little added damping without deadening the sound too much which can happen if you add too much damping to rear of driver. This reduced the 1-2KHz to the point that it is a non-issue. Sound is still lively & detailed but smooth as well & I found I can tolerate substantially higher volumes without discomfort. Soundstaging & imaging is improved & instruments sound correct. Treble is improved in level as is the sub bass. Been listening to a lot of classical music lately. Headphones are somewhat less sensitive now so requires a little more input volume in order to reach same output volume as before.

My friend that owns the studio records mostly classical music & is the principal studio that records the Seattle Collaborative Orchestra or SCO for short. His recordings can be found on you tube of that orchestra as well as many others so his information was invaluable in the tuning of the headphones.

 

[germanium]

This is a post I moved from another thread. I deleted the parts that didn't apply here.

I decided after further listening to make the following changes. I put some foam inside the ear pad behind the grill cloth to increase damping on the front side. I took the back off & placed 2 pieces of old t shirt, one was a bit more breathable than other & a piece of an old sweat shirt behind the driver then placed the original foam behind that & reinstalled metal back cover. I placed the old t shirt piece on back of driver first then old sweat shirt pieces before reassembly. I just thought that might be important.

One of the other things that that the foam damper on the front of the driver does is reduce interference from high frequencies from the outer edges of the driver that have to travel along the face of the driver to reach the ear canal. These interferences can cause significant peaks & dips in the response down as low as the midrange.

A couple of years ago I did null tests on my computer & discovered that even small differences in time between 2 identical files recorded at 96KHz & resampled to 768KHz to allow extremely small time shifts of one sample width at 768KHz sample rate & the total null collapsed to just over 20db null which is quite a loss of my perfect null. There was sound clearly into the upper midrange leaking. Program I used has on the fly resampling on playback just in case anyone was wondering. So reducing amplitude of the delayed high frequencies can reduce peakiness across a broad range of sound spectrum.

Sound is now less bass heavy & has significantly more presence& treble. I would characterize the sound now as very neutral. Sub bass is still present & because the earphones are less sensitive & require more drive sub bass actually improves some as damping has less effect on sub bass but is not out of line with mid bass. Mid & upper bass is reduced some which helps vocals immensely. Upper mid range emphasis is reduced allowing vocals to have more presence which results in smoother more airy vocals. Presence region is just above the upper midrange so reducing upper midrange exposes the presence in recordings. Violins in large orchestras are much more present in the sound stage. Stock it was hard to even hear the violins much of the time. Sound stage is quite large with excellent imaging. Pipe organ sounds excellent with great power at all frequencies including sub bass & great sound stage.

 

[germanium]

Comparisons between my speakers & headphones show very close sound signatures which is one of the goals that many headphone manufacturers shoot for. My speakers are slightly modified JBL LSR305's augmented with a modified Tannoy TS10 subwoofer with the goal of extending bass into the truly sub bass region which stock they woefully lacked in extension. I'm talking very usable response to 16Hz. The headphones truly go this low & even lower. Tonally they are nearly identical throughout their frequency range.

One annoyance though due to the high resolution of the headphones you can really tell the pan potted mono sources from the true stereo ones within the same recording. The pan potted sources are less dimensional than the true stereo ones & have a very different somewhat muffled character than the stereo sources especially noticeable if more than one instrument is present in a pan potted recording session when mixed along side a true stereo portion within the same song.