Perfect mod for AKG K702/701 -- simple, easy, no damage.

[IPodPJ]

[size=small]See post #6 for finished mod and post #9 for pics[/size]

I've been up all night listening to my new K702 wondering what I could possibly do to improve these headphones. I just got them the other day and they've been burning in day and night. They have an amazing midrange and soundstage, but their treble is less than admirable and the bass is just pathetic, not to mention the lack of instrument seperation. These drivers have amazing potential; it just needs to be tapped.

Now I can't finish this mod until I order more parts, but I did it in one ear. The results are positively amazing even with one ear modded and one ear without. It's simple, it's cheap, it's easy, it won't damage your headphones, it won't void your warranty and you will end up with one of the best headphones you have ever heard in your life.

I started experimenting by removing the earpads. Inside are these thin foam pad rings in the shape of a donut. I was wondering if they were necessary so I removed them and put the pads back on. I was blown away by how clear and extended the treble was! It was like the veil had just been lifted! But it came at a price. What little bass there was was now completely gone. "Why," I asked myself? Well it wasn't hard to figure out. The answer was staring me in the face.

So I once again removed the earpads. The foam ring partially covers the driver but it also covers these thin plastic or paper membranes running around the circumference of the driver that allow air to escape. With the foam removed, there was nothing to block all the air from escaping, but with the foam on, it blocked a lot of the treble! This led me to my second test.

I decided to double up the foam pads by putting both of them in the left earcup. This made it a little harder to reattach the earpad but with lots of pressure applied throughout the rotation, I got it after two attempts. Of course now, double the foam means less treble, but it meant LOTS of bass!! Most of the air wasn't allowed to escape now. So how can we combine the best of both worlds? Simple!

We take the foam pad donut rings and carve out a bigger circle in the middle. We leave just enough left on the perimeter of the pad to cover the thin membranes but leave a wide open space in the middle to leave the entirety of the driver uncovered. We put two of these foam rings in each earcup and we now have one of the best headphones in the world!!

I need to order another pair so that I can do both sides, but how expensive could these rings be? I'm sure they are very cheap but we just need to find out how to order them. I encourage everyone to try this for yourselves. Before you cut the foam pads, try listening to it without and see how much treble you get. Try listening to it with the foam doubled up and see how much bass you get. If you like what you hear (and there is no doubt in my mind that you will), help me find out where we can order more foam donut rings.

Once I locate a supplier I will provide step-by-step instructions with pictures. Everyone can do this easily themselves, but if they are uncomfortable doing it, I will offer an inexpensive modding service once I locate a supplier.

Now I say this is the perfect mod, but who knows....I might be able to get it even better! I am going to try experimenting with different kinds of foam and other materials such as a thin layer of wood and I will keep you updated of my progress. But at least now we have an excellent framework to build upon, if even necessary.

Happy modding!!!!!!

P.S. I did this on my pair of K702 but I see no reason why it wouldn't work on the K701 unless they use different materials behind the earpads.

Edit: I just did a search and found that people have taken the foam off before and some found it too sibilant. If you are in that category, you can do this mod to only one foam ring of the two that go in each ear. This way you're just allowing the bass to come through but keeping the midrange and treble where it was. Another option to go halfway between both would be to cut out a notch in the bottom foam ring that exposes only half of the driver. There are many ways to skin and cook a cat, but ultimately you have to choose which one tastes best. Have fun experimenting!

I have sent an e-mail to Frank Rodriguez at the AKG division of Harman. He is in charge of parts. Luckily, Harman International is only about 5 miles from where I live so I could just drive down there and pick them up, or he could mail them to me and I'll have them the next business day.

 

[CDBacklash]

Interesting, especially to come to the mod so quickly.

 

[V-DiV]

PJ, interesting. But why would you try to improve the sound of a raw K702 when it has a lot of changing to do? It is well documented around here. Even HeadRoom notes it. Once burned in (~300 hours plus) my K701s have great instrument separation. When not burned in the treble was rough and raw, but is very clear and extended when burned in. The bass on mine went through phases of development from just ok bass to big, powerful, but loose, to tight, textured, low-extended but somewhat recessed compared to the treble - just great for classical and other acoustic music. Wait until it burns in fully. Listen to it to find what it excels at. It is not an all arounder but it is awesome for some things. Then play with mods.

 

[IPodPJ]

Hi V-Div,
I've read tons of reviews around here and almost everyone concurs that there isn't any sort of punch to the bass. Burn-in improves certain aspects of the headphones but it does not turn them into something they are not; it will smooth the sound out but it won't magically make something appear. They have improved a lot since they have been burning in, but they did not suddenly take on a sound signature that wasn't there from day one.

The modification required to the Denon D5000 is an extensive one. The modification to the K702 is simple and then it surpasses the D5000. I already know the K702 stock does not sound natural. Yes, it has a very natural midrange and the speaker-like soundstage is also very natural, but it needs more fine tuning in other areas.

It is very simple to do yourself what I have outlined and is completely reversible. I suggest you try it and find out if you like it or not.

Bass notes that you couldn't hear before are easily defined. Nothing is muddy, it's very clean and textured.

 

[Punnisher]

I have also thought about doing something to this effect.

Though, treble and separation seem to be the best traits of this phone. IMO of course. Better imaging than my dt880.

 

[IPodPJ]

UPDATE!

I took out a foam packaging block from the box my CIAudio VDC9.0 power supply came in. I spent the past two hours slicing it in half with an X-Acto knife and then carving out the foam donut rings to my specifications.

It sounds superb! The openness of these headphones are still very plentiful because the backside of the driver is still open. Soundstage and instrument seperation are improved. The bass is now punchier and extends lower, but don't worry... it isn't powerful like a closed headphone, it's just perfect! The thickness of the foam ring backed the midrange off by about 10% which is just enough to remove some honkiness it had and balance out the entire spectrum. Treble isn't sibilant at all, just super smooth. I'm using the DAC in my Opera right now which is just an average quality DAC. I'll be able to give better impressions on Tuesday when my PS Audio DL3 comes back from being modded by Reference Audio Mods. If it sounds this good now with Opera's DAC, it will sound unreal with DL3.

I'm in love with these headphones now. Anyone coming to CanJam will have a chance to listen to them.

I'm going to locate a foam molding facility and inquire about having foam rings custom made to my specifications.

 

[dcpoor]

this thread needs pictures of your mod.

 

[IPodPJ]

I only have a cell phone camera now which is garbage, but I will take pictures of it today.

 

[IPodPJ]

[size=medium]PICTURES OF PADS[/size]

[size=small]These pictures show the differences between my pads and the stock pads. They are not a work of art, but they work great. I am going to find out about getting some custom made to these specifications. I would need to know how many people would want them.[/size]

[size=small]Both drivers with my new pads[/size]

[size=small]Single driver with my new pad[/size]

[size=small]Driver with stock pad[/size]

[size=small]Driver with no pad. You can see the thin white membrane here. This is what needs to be covered up.[/size]

 

[Zombie_X]

I tried this out with some of the packaging foam from my Grado's. It's sounds different, but appreciable non the less. I think I'll stay with the stock for now, but I say that's a good mod for those seeking more bass.

 

[limin]

have you tried taping up the outside of the pads? also taping up the inside of the pads. I had a feeling like a lot of the bass in these headphone was lost through the frankly huge and airy pads, so i tried using some scotch tape similar to the grado basshead mod but with a small, 1/8th inch strip on the inside of the pad as well and it has, in my mind, done the same as what you have said except without altering the treble, so maybe that is also an option for those who would not like extra treble.

 

[Zombie_X]

I haven't tried it that way, but maybe t'll help like with the Grados.

 

[K_19]

Hmm, I should fool around with this mod so it is more bass centric then use it with my EF1 with the RCA tube. Trust me, anyone would take the whole business about K701 treble being rolled off after using the RCA cleartops. It's borderline sibilant!

So a thicker foam is what brings the bass?

 

[IPodPJ]

Yep. It brings the bass, but there is only so much you will get. It still won't sound like a Denon.

Each can has their purpose and while I love both of these cans, the K702 + mod is my favorite right now. I'm hearing detail in the bass I just can't hear with the D5000.

Limin,
I would strongly advise against taping up any part of your headphone to cover these ports. That will void your warranty if they see sticky remnants on there. The membrane is a very thin, ridged material and I don't know what it's purpose is completely. I wouldn't want to fully block it and prevent all air from escaping. Also, tape will resonate and that won't be a pleasant addition to your music. The foam attenuates and filters the sound which is why the thin pads are there in the first place. You can experiment with different kinds of foam and try making pads that leave part of the driver exposed and part of it covered. I definitely find that the thicker pad smooths out the midrange. I may do some other experiments to bring out more bass (without losing quality) and reduce the treble by just a tad. I think a piece of foam like mine but that was angled would be even better. If I knew how to get behind the driver I would also try putting some Dynamat Xtreme on the driver assembly.

 

[IPodPJ]

UPDATE #2:

After more listening I found the treble to be too sharp. But with the stock pads covering a good portion of the driver it killed the treble.

So I took the stock pads and trimmed about 5/32" off the center of the circle. Then I put the stock pad below my pad. The treble was nice now but the midrange was a little lost for detail. What else would work? I took the earpads off and tried putting the newly shaven stock pads on top of my pads. This now brings both the treble and midrange to perfect levels. The bass has just lost a little detail so now I will be working on that.