Pictures of the mods will be posted Wednesday of this week.
After owning the AKG K701 for about five-months, I now have an understandable appreciation for those who like and hate its sound signature. Coloration is not I would describe these headphones. It is the sheer clarity these headphone possess in comparison to their rival headphone, the Sennheiser HD650. Two different philosophies in terms on how to build a headphone to represent or reproduce the source recording.
The Sennheiser HD-650 leans toward the warm side with a slightly muffled texture. It is like sitting six rows back center, which provides good sonic imaging with the stock cable. The Cardas cable upgrade is a basic starting point and quite needed to remove some of those muffled characteristics. Sound-stage is improved significantly with more details presented, however the warm character of these headphones are still present.
Now take the AKG K701, a well designed headphone with metal alloy arches and a single cable entry is well thought out. In fact that would be my preference since it is easier than having the traditional Y-type cable or convenient. One thing I do have to say is that a considerably longer duration of time is required to break-in the headphone drivers (1000-hours). The stock cable is actually pretty good with this type of headphone. An upgraded cable will probably improve the overall dynamics however after the simple mod and placement, I feel that a cable upgrade will still improve the sound-stage, however will not be required.
The K701 Simple Mod
Using a piece of synthetic chamois cloth, I basically cut identical pieces matching the foams that cover over the headphone driver grills except that instead of a circle pieces with a hole in middle, I basically cut a 1/4 out therefore creating a 3/4-circle with a 1-inch diameter center piece cut out placed over the driver grill. The position of the cloth determines the overall sound-stage imaging and surprisingly it works to a great degree.
Most of the harshness and brightness of the audio signature is virtually non-existent. The bass is much stronger and tighter than with the original foam pieces. Surprisingly, that is, my headphone audiophile friend of mine basically hated the K701 said, "I can't believe what a difference a piece of material placed over the driver can make. Changing the dampening material actually changes the headphone from harsh to very neutral."
It is always good food for thought when someone who has a very big distaste with the K701 to say something good about it.
As stated in my last new thread, I have been considered by many of my audiophile peers as having a very unbiased ear for many if all things in the audiophile world.
So I can understand the hate with these headphones. All brands of headphones have distinct audio signatures that define them. The K701 is very clear with a hint of harshness and brittle feel in the sonic quality. Give it a little time and understand that resorting to changing the cable doesn't necessarily change the original character of the headphones or the drivers. I have a physics background and I am also good with out of the box creative thinking, so understanding these headphones and how to iron out the problems with its sonic character is a walk in the park.
Before the haters start to question my sanity with these headphones, one must understand that these companies put a great deal of effort in designing, developing, and producing these headphones. Driver placement and how it beams the sound to our ears is all about research and development. If the AKG K701 or any of their high-end models were perfect in many or every regards, then their wouldn't be people out their making modifications to make them better (highly unlikely, there is always room for improvement).
The change in dampening material and the placement really has changed the sonic character towards the better with the K701. I suggest the owner who currently own the headphone to give it a try. I will post the images tomorrow Wednesday during the day to show the modification applied. The Brittleness, the brightness, and the harsh overtones are virtually removed from the sound-stage, sonic quality, and the bass is further strengthened and tightened with this simple change in dampening material.
I hope this helps with the other K701 owners out there. Have a great week everybody.
Source output is from both my audio system and in most cases from my audio box with 90-percent of my rips in Apple Lossless Codec. The headphone amplifiers used for the A/B test between standard foam dampening material and the mod are the Little Dot MKI (LT1364 op-amp upgrade), and the C&C XO+. Interconnect used is the Moon Audio Blue Dragon Version One (V1 is with silver conductors while V2 and V3 are copper).
Any questions feel free to post them. Again have a great week.
Pictures and update description to the placement. Note the exact position of the opening 1/4 of the ring. This opening places the soundstage close to 3-row center rather than the 6-th row with the original foam ring.
Friday, October 29th 2010. Final images of Mod Posted
Since the first time I posted images to today, I have made little changes here and there to make what I am going to put down in this forum post worth the wait (I Hope). Orientation of this modification is important to determining sound stage presentation, dynamics, mid-range response, treble response/extension, and bass depth/impact/level. Our ears are the best listening devices over a microphone, but being a physics researcher and scientist, I decided to attack the project using a bit of science (more like having an audio engineer from Golden Era Productions in California to get specific Frequency Response figures to add to the already impressive figures posted).
Using the Serial Number as reference orientation, as shown through the mesh, the modification performed used a particular material defined by the Germans as a synthetic chamois but here in the US, it is a drying cloth used for automobile applications. I find that this is closest and thinnest material suitable for use with what I hope to achieve here (I have tried paper which in turn rattled when certain frequencies were reached, paper towel from brawny provided a similar response range to the original foam dampers, etc.) I made many changes and found that the center opening is a must have if any treble range is desired. This opening also helps in sound stage presentation, imaging, dynamics, and the airy presence that has attracted me to purchasing these headphones.
In this picture here I have removed the ear cup displaying the orientation more or less of how the 3/4 ring with the 1/4 cutout reflector (more on that in the following images) placement. The first, and second post in regards of this modification I left an open C type arrangement in order to retain many of the original characters of the headphone. The result was very positive in my point of view hence that is why I posted the mod to see if others can benefit or experiment with this idea. However after many months of changing interconnects to at soften the treble sibilance, I decided to use the remaining material to cover the open C unfortunately the result was the treble range was reduced significantly. Using an AKG series microphone, the response sampled was 18-hz to 28.9-KHz +/-3db. From my hearing standpoint though I felt as cotton were stuffed into my ears. Bass was no longer deep but with a great deal of boom. This was unacceptable.
This was the first post's original modification and as described from the previous paragraph, the sound stage was open and airy but a bit sibilance was detected and with my ears I had to make changes to further soften the blow. While I was thinking of a solution for the problem, I continued to listen to the headphones well past 1000-hours in this modified state. The little tabs of masking tape are used to keep the open-C damper from shifting position whenever I remove and replace the ear cups back on to the headphones. Note the actual orientation of the open-C in relation to the plastic frame grill covering the driver. The position of the open-C allows for certain mid-high frequencies to be beamed into the outer and mid ear structure. This was pure coincidence since I wasn't thinking about it at the time until my audio engineer pal of mine stated this fact to me.
While my audio engineer friend was asking for some computer advice, I decided to take advantage of his presence when coming up with this ridiculous idea to custom cut some black electrical tape and cover one side of this 1/4 part of the ring damper to form a reflector of sorts. My Audio friend stated that this should help channel some of the upper frequency registers to the center and other surrounding areas. Since she was an audio engineer, I decided to continue with this until I created to identical pieces for left and right ear pieces.
As shown in this image, It would seem that I have covered the remaining portion of the driver to complete a ring damper and one would say that would cause the frequencies to become subdued. That is why I displayed the image with the electrical tape. The taped side faces down thus creating a first surface reflective layer. Does anybody remember Room Tunes?
I used the similar concept creating a damper one side and reflective on the other. I find different listening results when using reflective and damper. This little piece actually changes the audio character for better or worse in many cases. When face down, the sound stage is wider and deeper, dynamic range is still very well balanced, while the treble frequencies are clean and clear with virtually no sibilance in its overall character even when played to moderately high volumes. The Audio Engineer decided to add a little science to the mix by testing its frequency response before and after this final application of the mod (published specs 10hz to 39.5-KHz - Tested 12-hz to 39.8-KHz +/-3db - First mod 18hz to 28.4-hz +/- 6db - Final Mod 10-Hz to 39.8-KHz +/- 3db).
No boom in bass or att. of mid-high frequencies detected between stock foam dampers and final modification to the damper. The reflection pad actually helped in the dynamic presence and further expanded the sound stage to the point it reminded me a little of the Sennheiser Orpheus.
A Pulled out image of the modification orientation using the right ear cup POV as perspective. I also created the same reflective layer on a separate set of open-C dampers for reference sake and the sibilance returns with a vengeance hence I will leave it out of headphones for like say a very warm Sennheiser HD650 for future reference.
This is it for this modification. I like the sound as it is right now versus stock since I can listen for extended periods out time without having any form of listening fatigue. I am always open to suggestions, however saying that this mod will not cure anything is only dependent on the configuration. I have five portable headphone amps and six desktop amps for my already expanded collection of headphones. With the exception of the Sennheiser Orpheus, I have open headphones made by Beyerdynamic and AKG that give me great listening pleasure when I am not listening to my Audiophile style home listening environment.
Everybody, have a very scary weekend and enjoy that candy.
Edited by yklee118 - 10/29/10 at 5:37pm