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ADU
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AKG K553 Pro tweaks, maintenance & discussion

I recently purchased a pair of AKG K553 Pro headphones, and thought I'd share a few of my observations and tweaks for certain fit, seal and balance related issues with these headphones, in case others here may be encountering similar issues.

The tips here are mainly for experienced modders, tweakers and tinkerers. If you don't fall into that category, then you may want to think twice before trying some of the suggestions here. The "headband fix" is relatively easy though, and may help to improve the fit, seal and comfort for many users.

Some ideas discussed here could possibly void the mfr's warranty btw. So use all the info/ideas here entirely at your own risk. I make no warranties, express or implied about the info.

K550 & K551...

The info/tips here may work with the K550 and K551 as well, since these headphones are based on the same design as the K553. (I don't think there was a K552.)

DESIGNED FOR LARGE AUSTRIAN HEADS (BUT CAN WORK WITH OTHERS TOO)...

Unless you have a rather big head, the cups on the K553 headphones will probably hang too low on your ears, even with the headband extenders completely retracted. This makes it difficult to achieve a good seal around the bottom of the ear pads, and a consistent sound.

In his mostly positive K550 review, which can be found here,...

http://www.innerfidelity.com/content/wonderfully-competent-akg-k550-seal...

...Tyll suggests bending the headband more downward to rectify this issue. Imo, that will position the drivers too low in relation to your ear canals and drums, and distort the sound.

My solution was to add some more padding to the headband.

For a temporary fix, all I did was take a piece of soft thick cloth and wrap it around the headband, and secure it in place with a couple of rubber bands. Smaller heads might need some actual foam padding though.

There are "after-market" headband pads for other headphones which could possibly be adapted for the AKG K553 as well.

MEMORY FOAM WITH A MIND OF ITS OWN...

Imo, the original memory foam inserts in the ear pads are also too small, too soft, and too pliable, and they move around too much inside the pleather covers to deliver a consistent fit, seal and sound.

If you have bigger ears, or ears that stick out more than average, there's a good chance they won't fit particularly well into the pads, or may press against the grille covering the drivers, possibly enough to break the seal on the headphones. Even if you don't have these problems though, the excessive pliability and movement in the K553's ear padding can still make it very difficult to achieve a consistent seal and sound.

I have relatively normal shaped ears that are probably a bit on the large side, and they sometimes touched the cloth covering the grille inside the ear pads. I need/want a very consistent sound and seal for my listening though, and didn't feel the original memory foam inserts were making that particularly easy, for many of the above reasons.

When I turned my head, the seal would often break on one side. Or I could feel changes to the pressure in my ears because the ear pads weren't seated well, and were shifting around. (The stiffness in the headphone's joints and hinges didn't help with this either.) I was continually having to reposition the headphones and cups to maintain a consistent seal and good L/R balance in the sound.

My solution to this problem was to make my own foam inserts from a slightly thicker and larger piece of standard low-density foam. A 12" x 12" x 1" thick square of this foam is only a couple bucks at Hobby Lobby, and it will make at least 4 inserts.

If you're not a fan of bright sounding headphones though, then you may want to find some 3/4" foam instead, because the thicker 1" foam makes the sound seem a little brighter to my ears. I looked for 3/4" foam in my area though, and couldn't find any.

The overall fit and sound quality is much better and more consistent with the new pads imo. And I plan to EQ the headphones. So hopefully that'll take care of any add'l brightness in tonal balance.

If you try replacing the inserts, use some care removing and replacing the pads, because the pleather covering is pretty thin, and could tear if its pulled or stretched too much. There is also a white ring of fabric that's rather poorly attached to the grille plate which may come loose if you screw the pads back on to them with too much force. (More about that issue below.)

There are notches on the sides of the grille plates to help reattach the ear pads. You put the "lip" of the pad over one side of the notch, and then turn the pad like a screw to thread it back onto the cup.

STIFF JOINT SYNDROME...

The joints and hinges in the K553 are somewhat stiff, so the cups do not conform to the shape of your head and ears as readily as they might on headphones with looser joints. You have to be more "pro-active" about positioning and aligning the cups on your ears to achieve a reliable, consistent seal.

There's much less fiddling needed on my headphones with the new padding on the headband and ear cups though.

RING AROUND THE GRILLE PLATE...

As mentioned above, there is a thin white ring of fabric covering a set of tuning holes in the grille plate, which can easily come loose.

The fabric damps the sound coming through the tuning holes from inside the cups. So if it comes off (as it did on _both_ sides of my headphones), it may cause a noticeable imbalance or change in sound quality, probably toward the brighter and/or louder side. I suspect this is one of the primary causes of balance-related complaints on this, and similar AKG models.

Securing the rings before they come off with some small pieces of tape around the edges might not be a bad idea. If they come completely off, then you may want to try gluing them back on. (Again, use these ideas at your own risk and peril, as they may well void the warranty.)

If you tape the rings back in place, as I've done for now, then you want to carefully position the strips of tape, so they aren't covering any of the tuning holes, or holes in the grille.

A defect like this should be covered under the warranty. The rings are attached so poorly though, that they may come off on any replacements as well, unless they're handled with extreme care. So you may just want to deal with this "in-house", as I've done.

The more you remove and fiddle with the pads, the greater the chances are that the rings will dislodge. There's also a good chance they'll come off just with normal usage though, due to accidental turning of the pads. (You could also try taping the pads to the cups, to keep them more stationary.)

IF YOU LOSE A RING...

...And can't get a replacement, or new headphone from AKG, don't panic! Another possible solution is to cut the remaining ring into enough pieces to cover the tuning holes in both grille plates.

There should be 3 to 4 holes in each plate. If so, then you might want to try cutting the ring into 8 - 10 smaller pieces of fabric, so you have a few spare pieces, in case one or two get lost.

Make the pieces large enough so you can tape or glue them across each tuning hole, without covering the holes with any tape.

Before going to all that trouble though, look carefully inside the lip of the ear pad to make sure the lost ring isn't stuck somewhere in there.

CRINKLY DRIVERS...

If you remove the pads (at your risk), and look through the grille that covers the drivers, you should see a clear plastic "bubble" with a pattern of spiral indentations around the edges. That bubble is the diaphragm which vibrates and produces the headphone's sounds. And it's extremely delicate and sensitive to changes in pressure. (If you blow on it lightly, you can probably see it move slightly, it's that sensitive.)

If the headphones are handled or mfr'd improperly, the clear plastic diaphragms may become dented or deformed (aka crinkled), or possibly even cracked. And you should be able to see the dents through the grille. A pocket LED flashlight and/or magnifying glass might help with this, but you should be able to see any obvious dents with the naked eye, if you have decent close-up vision.

If there's a bad dent in only one diaphragm (either left or right), that could also cause an imbalance in the sound.

Most people have some imbalances at different frequencies in their hearing though. So if you think you're hearing differences in sound quality between the left and right ear cups, you may want to run some more thorough tests (with frequency sweeps and such) to better determine whether the problem is in the headphones, or your gear, or your ears.

DO NOT!... I REPEAT, _DO_NOT_ STICK ANYTHING THROUGH THE HOLES IN THE GRILLE UNDER ANY CIRCUMSTANCES! AND NEVER, EVER, _EVER_, USE A VACUUM OR ANY OTHER SUCTION DEVICE TO CLEAN THE EAR PADS WHILE THEY'RE ON THE HEADPHONES. ALSO, DO NOT PUT ANY EXCESS PRESSURE ON THE CAVITY IN THE EAR PADS.

All of the above can damage the clear plastic diaphragms. If the diaphragms are dented or damaged, imo the headphones should be returned, or fixed/replaced under the warranty.

Some other headphone geeks may suggest squeezing the ear pads together and then releasing them to "pop out" the dents. I wouldn't advise it though, because it may make them even worse. And if the dents were caused by a manfacturing error, they may just come back again. So my advice is to return or replace the headphones.

You may see a thin copper wire along one side of the "bubbles" btw. That's normal and it's part of the headphone's driving mechanism.

There's more info on how the diaphragms in dynamic headphone drivers work here...

http://www.innerfidelity.com/content/how-headphone-dynamic-drivers-work

ADVANCED MODDERS/TINKERERS ONLY...

If you're a highly tech-savvy person (note, I said _highly_ tech-savvy), and good with your hands (ie not ham-fisted), there are a couple other items worth checking out inside the headphone, like the solders and rubber dampers.

Some of the parts are a little difficult to put back together though. So I would NOT advise this for the majority of users. (I asked AKG to email me a schematic of the headphone, so I had a better idea how the parts went together before attempting this.)

If you're an experienced modder or an overly curious tinkerer type, and ABSOLUTELY MUST see what's going on in there though (at your own risk!), then the grille plates can be removed by simply loosening the five small screws around the white ring. Be careful when lifting the grille plates, because the drivers are glued onto the back of them, and attached to the headphones with some wires.

Tinkering with any of the innards will probably void your warranty btw.

LIST OF METAL COMPONENTS...

There's a lot of metal in the K553. That's a good thing in my book, because it makes the headphones potentially more sturdy and durable, and also able to deliver more impactful bass, due to greater inertia. (Lighter weight headphones like the Beats Solo2 and Audio Technica M50x rely more on a high clamping force and tight seal to achieve this, making them significantly less comfortable on the ears.)

The following components are metal...

- The headband.
- The cup handles
- The trim and disks on the back side of the cups.
- The hinges in the cups.
- The screws in the grille plate and cup handles.
- The backplate on the drivers.
- And probably also the swivel hinges in the cup handles (which I didn't bother to take apart).

DAMPING...

There is a very thin layer of damping material on the back of the metal disks in each cup (which is slightly visible behind the hinges on my K553). So there are also multiple damping mechanisms at work in this headphone, including...

- The fabric that covers the grilles on the pads.
- The white rings covering the tuning holes.
- The rubber "spacers" that fit between the main drivers and metal hinges in the cups.
- The foam on the back of the metal disks on each cup.

SOUND QUALITY: ON THE BRIGHT SIDE & SOMEWHAT LACKING IN WARMTH, I THINK...

I'm still assessing the tonal quality and left-right balance on the K553, and may have more thoughts to add on this later, after some more thorough EQ tests.

My initial impressions though are that the K553 is well-extended in both the high and low frequencies. But the upper half of the treble is a little too pronounced, and possibly not as well-balanced from left to right as the mid and low frequencies. Overly-compressed sound sources will sometimes sound a bit shrill and grainy. And using thicker ear pads (like I'm doing), or losing a white ring may also increase that brightness.

The upper half of the bass and possibly some of the midrange also seems a bit thin and lacking in warmth with my equipment. I don't use an amp though, which might help a little in that department.

The sound may be somewhat different on the K550 and K551 btw.

MY PERSONAL SOUND PREFERENCES...

I tend to prefer a slightly darker leaning (and more "neutral" imo) sound than the average headphone audiophile. That's based on looking at numerous plots of headphones popular with audiophiles in both the Inner Fidelity database and a similar Korean headphone database (Golden Ears). And comparing their frequency response curves to the roughly dozen or so headphones I've tried.

PRICE & AVAILABILITY...

The AKG K553 is available at both Guitar Center and Sam Ash (both do price-matching btw), and also through many online retailers. It has also been offered through the group discount Massdrop website at a reduced price.

Current retail is around $170 to $200. But this headphone frequently goes on sale for less. I bought my K553 headphone on sale at Guitar Center for $130 + tax. And the Massdrop deal was in the same price range.

OTHER RESOURCES...

In addition to Tyll's K550 review (already mentioned above), some of the issues discussed here may also be addressed in the AKG K550 and K553 threads at head-fi.org...

http://www.head-fi.org/f/4/headphones-full-size

Graphs of the AKG K553 have not been posted yet by either Inner Fidelity or Golden Ears. There are some graphs of the K550 and K551 here though...

http://www.innerfidelity.com/images/AKGK550.pdf
http://en.goldenears.net/13746
http://en.goldenears.net/17012

That's it for now. But I'll try to update the above with more info as it becomes available and/or applicable.

Happy AKG-ing folks. :)

ADU

ADU
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Update #1

Already added a bit more info, including some pricing info, a list of metal parts in the headphones, and what to do if a tuning ring gets lost. :)

I also forgot to mention that the drivers are glued into the back of the grille plates. So special care needs to be taken when separating the grille plates from the cups, or some wires attached to the drivers could be damaged.

ADU
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Update #2

Updated the "crinkly drivers" section.

gibtg
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Measurements?

Has Tyll measured or listened to these?

ADU
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Howdy gibtg,
gibtg wrote:

Has Tyll measured or listened to these?

Not that I know of.

Cosmetically, the K553 is the same as the K550, that Tyll previously reviewed (linked above). I think there are some differences in the sound quality though, based on some graphs posted by another site. And I think some of my initial impressions of the K553's sound quality were probably also a bit off.

The stock K553 does sound a bit bright to my ears, and lacking some warmth. Most of the brightness seems to be coming from the _lower_ half of the treble, and also the midrange though, rather than the upper treble as I previously speculated. However, there also appears to be a little depression somewhere around 3 to 4 kHz in the low treble.

So I guess you could describe these hadphones as being a little heavy or harsh in the mid-range, or upper mid-range, with possibly a little too much emphasis around 6 kHz or so in the treble as well. And maybe not quite enough emphasis around 3-4 kHz. That's still rather tentative though.

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