germanium
Headphoneus Supremus
The headphones in question have very different sound starting out the gate. The Gold Planar GL400' are very full sounding but dark due to reduced treble where as the Sennhieser HD25's are very bright but have good strong lower midrange as well but with room be able to increase the midrange output considerably & are somewhat weak in the bass but not totally lacking. Bass is the very strong suit for the GL400's both in level & detail.
The GL400's are open back planar magnetic headphones where as the HD25's are closed back dynamic driver headphones.
The GL400's are a little too warm out of the box so I improved the damping on those by adding a second thin foam piece behind the felt damping pad to press the felt pad against the back of the driver more firmly thus increasing the damping. This is all that was needed to get the GL400's to sound the way I wanted which is very smooth in frequency response with improved detail & mildly improved treble level relative to the midrange.
The HD25's were way too hot in the treble & female voices were very shout on the upper range, not very natural at all sonding whereas the GL400's after modificationtwere very natural sounding with good life but not over bright or shout.
My modifications to the HD25's were
1. Turn them into Semi open headphones by removing outer cup. In doing this the mounting hardware for the headband stays with the inner driver mounting frame so you can easily convert to open or semi open operation I chose semi open in order to get the the deep bass response I wanted as the front of the driver-earpads would not leak much sound when finished only the back would be open to the outside world. I put tape around the outer part of the driver mount for the same purpose of sealing off the front of driver from outside world when listening.
2. I removed a portion of the damping paper from the center of the front damping pad fully uncovering one hole in the center. This got me close but no cigar to the proper midrange to treble balance.. Treble was still slightly too hot but much better than stock.
3. I took a piece of 22 gauge wire & poked 6 small holes in paper damping pad around the perimeter of the center hole. This brought the sound so close to the GL400 that you would be hard pressed to reliably tell the difference which was which.
I chose to match the HD25 to the modified GL400 due to the fact that I liked the sound of the GL400's a lot once I did that one very simple modification on them. Where as the GL400's required more damping to get desired sound & I had already maxed out the potential that damping would accomplish. The needed modifications for the HD25's involved actually reducing damping very subtly in order to bring midrange level up to treble level volume wise. Running the front side totally closed brought bass up to the needed level. Frequency response is now nearly matches the GL400 for smoothness & general overall balance.
The GL400's are open back planar magnetic headphones where as the HD25's are closed back dynamic driver headphones.
The GL400's are a little too warm out of the box so I improved the damping on those by adding a second thin foam piece behind the felt damping pad to press the felt pad against the back of the driver more firmly thus increasing the damping. This is all that was needed to get the GL400's to sound the way I wanted which is very smooth in frequency response with improved detail & mildly improved treble level relative to the midrange.
The HD25's were way too hot in the treble & female voices were very shout on the upper range, not very natural at all sonding whereas the GL400's after modificationtwere very natural sounding with good life but not over bright or shout.
My modifications to the HD25's were
1. Turn them into Semi open headphones by removing outer cup. In doing this the mounting hardware for the headband stays with the inner driver mounting frame so you can easily convert to open or semi open operation I chose semi open in order to get the the deep bass response I wanted as the front of the driver-earpads would not leak much sound when finished only the back would be open to the outside world. I put tape around the outer part of the driver mount for the same purpose of sealing off the front of driver from outside world when listening.
2. I removed a portion of the damping paper from the center of the front damping pad fully uncovering one hole in the center. This got me close but no cigar to the proper midrange to treble balance.. Treble was still slightly too hot but much better than stock.
3. I took a piece of 22 gauge wire & poked 6 small holes in paper damping pad around the perimeter of the center hole. This brought the sound so close to the GL400 that you would be hard pressed to reliably tell the difference which was which.
I chose to match the HD25 to the modified GL400 due to the fact that I liked the sound of the GL400's a lot once I did that one very simple modification on them. Where as the GL400's required more damping to get desired sound & I had already maxed out the potential that damping would accomplish. The needed modifications for the HD25's involved actually reducing damping very subtly in order to bring midrange level up to treble level volume wise. Running the front side totally closed brought bass up to the needed level. Frequency response is now nearly matches the GL400 for smoothness & general overall balance.
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