AKG K121 Studio

Greetings!

Today we're checking out a discontinued model from AKG, the K121 Studio.

I'm no stranger to AKG having spent ample time with a number of their products, like the K512 mkII, K701, and my favourite, the K553 Pro, among others. I recently added the K121 Studio to my collection having found a roughed up copy at the local thrift shop for a whopping 3.99 CAD. The elastics that support the headband had completely deteriorated, the pads were falling apart and the tuning foam covering the drivers was shredded and disintegrating into tiny particulates. They were a mess, and therefore, the perfect candidate to come home with me.

Once home, I dug in and started the restoration process. Beginning with the pads, they were removed and all the foam and faux-leather shreds eviscerated. The K121 was then given a deep clean and sanitize to remove any remaining dirt and debris. Since the stock pads were no longer usable, I cut off the pleather material to get at the plastic plate that clips to the ear cups. The inner foam was still in great shape, so that is being kept in case I feel motivated to make new pads similar to the stock set. Stock Meze 99 Neo pads were installed in their place since they were the only set I had that fit even remotely well enough.

Since the K121 is easy to work on and quite modular, replacing the headband elastics was a cinch. Starting on the headband, there are two square plastic slabs, the lower of which needs to be removed. It's as simple as removing a single Philips head screw. From there, the structure falls apart revealing a plastic disc which the elastic is attached to. Just rip the elastic off (or cut it...). The AKG branding sticker on the cups was next to go, carefully peeled off to reveal a screw underneath. After that was removed the plastic cover came off revealing some wires and another screw securing the headband rails in place. Removing that final screw released the elastic which was wrapped around a small tab, hidden amidst the wires. Since I had no similar, cloth-coated elastics to replace the stock ones with, small blue ones that commonly come with vegetables were recruited. One end was wrapped around the tab on the ear cup side, then screwed down, and the other wrapped around a stabilizing pole on which the plastic disc then rested. Everything was screwed down, the stickers replaced, and ta da! The K121 Studio once again had a functional, self-tightening head band along with new pads. With these repairs in place, the K121 Studio was ready for use.


This wasn't an expensive headphone when new, so it comes as no surprise that the build is almost entirely plastic, save for the vented, gold-coloured portion of the ear cups which is metal (or at least it feels like it). The plastic seems pretty low rent, but significantly nicer than that used for my old K512 mkII, the headband rails in particular. The rails on the K121 Studio have some structural rigidity to them, while the rails on the K512 mkII literally felt like flattened straws. The headband is clearly plastic as well and doesn't do a great job of mimicking leather, but after it was cleaned looks brand new. It certainly held up better than the pads and elastics. All this plastic means the K121 Studio is impossibly light, which is exactly what I'd want for a product intended to be used for long periods in a studio. I can wear it for hours with the only discomfort coming from the Meze pads which are quite a bit larger and deeper than the stock set, adding additional pressure around the ears that requires short breaks to address. I'm sure that with pads more akin to the stock set, comfort would be a solid 10/10 instead of the current 8/10. Isolation isn't great which is no surprise. The semi-open back design lets in plenty of outside noise which is fine indoors, not so great outside. Not that you'd want to use these outside anyway thanks to the fixed, 3 meter long, single-sided cable which btw has great strain relief at the straight jack and leading into the ear cup.

Since I've not used them with the stock pads, which to be frank were disgusting, my sound impressions will be based purely on use with Meze's pads. I also like to use them with some mild EQ (-4dB@9k, -2dB@5k) to take down peaks in the highs, likely a result of the pads since those peaks are greatly lessened when squishing the pads to something more resembling the stock depth. They have been used almost exclusively with my Hifi E.T MA8 DAC and TEAC HA-501 desktop amp + ADC Sound Shaper Two mkII equalizer with the MA8 or my laptop sourcing the beats.

My expectation of the K121 Studio was that they would sound similar to the K512 mkII with a decidedly lean, bass-lite, mid and treble focused sound. What I got instead was a more robust, reasonably well-balanced headphone, though still with some extra upper end energy. Bass is surprisingly robust and well formed with good extension as noticed in the opening moments of Kavinski's “Solli”, even though the K121 Studio is saddled with quite a small driver (~30mm). Emphasis isn't much beyond neutral, keeping with the idea of it having been designed with monitoring in mind. Texturing is excellent with nothing being smoothed over or overly warm, and speed is quite nimble. Distortion can be a problem when not properly amped though. While reasonably sensitive at 114dB the K121 Studio is fairly easy to get up to volume, however, the above average impedance of 55ohms means you need something capable of letting it run smoothly at said volume.


My first test after being cleaned and prepped for use was with the Cozoy Takt C because it was already plugged in and ready to go. Distortion on every bass note was immediately apparent. If you've been following my content for any length of time, you'll know I typically listen at low volumes so this came as a surprise. If you're planning to use these with your average portable source (ex. Shanling M0, FiiO M3 Pro, etc.), I suggest getting at minimum the Earstudio HUD100 and running it via the high output port which can bring it up to blistering volumes, distortion free. The VE Odyssey HD works if you're on a tight budget, just note that the two together end up sounding somewhat artificial thanks to a metallic edge added to the presentation.

That out of the way, let's dip into the midrange. Note weight is satisfying with vocals and instruments having just the right amount of body. Nothing sounds overly thick and muffled, nor is it lean and sharp. Listening to Aesop Rock's 'Spirit World Field Guide' I was quite surprised at how well the K121 Studio handles sibilance. This album has a very hot midrange that with the vast majority of headphones and iems is way too aggressive. Totally listenable with the K121 Studio though. Clarity and detail are quite good, improved further by removing my earlier EQ suggestions, though it comes at the expense of listening fatigue. In my opinion, my alterations find a satisfying balance between comfort and clarity. Timbre from the K121 Studio is quite natural with just a hint of dryness in the higher registers leaving cymbals and chimes less shimmery than you'd expect. Otherwise, most excellent.

Speaking of the upper registers, the K121 Studio falls in line with my general experience with AKG products. A solid lift in the presence and brilliance regions resulting in a very crisp, generally detailed signature with plenty of air and space between notes. This particular model suffers from a fair bit of splash that knocks it down a notch in terms of retrieving micro-detail, though it's a sub-100 USD headphone that is how old and with who knows how much use, along with oversized third party pads, so for all I know the pads could be a terrible pairing, or maybe the headphones are simply old and worn out. Even so, notes attack with plenty of force and decay rapidly resulting in an energetic, articulate sound that doesn't get easily tripped up by busy passages. I have no problems listening to improvised jazz or metal with these since they do a great job of sorting the mess of noise into a coherent passage of music that can be scrutinized, splash and all.


When it comes to sound stage the K121 Studio is plenty wide and deep, besting even the K553 Pro which sound more like an open back than the closed back they are. Vocals by default sit outside the head with sounds and effects having plenty of space to move about. Numerous times when listening to the K121 Studio I thought I heard something behind me, or my wife was asking me a question, when really it was just some aspect of the soundtrack fooling me. While I don't find a large stage necessary for listening enjoyment, it certainly helps. Imaging is nice and precise too with channel-to-channel transitions happening smoothly. Tracks also come across very well layered with each instrument clearly defined and easy to track. It doesn't take much effort to accurately follow movement when gaming, though the limited bass quantity may keep the K121 Studio from being ideal for the medium for some users.

So was the AKG K121 Studio worth the four bucks and some TLC to bring it back to fighting form? Well, yeah, definitely. Not only do they look cool, but they're very comfortable, easy to work on, and they sound shockingly good. They're not without issues, like cheap materials and occasionally splashy treble, but I can look past those issues given the price paid. Heck, I'd still have been happy with them at their original retail price of 89.00 USD. They're just a rock solid, inexpensive monitoring headphone with enough life in them to keep from sounding sterile. While their low end can't be boosted much without running into issues, the rest of the signature is plenty receptive to EQ and can be altered and messed with at will.

If you're not afraid to buy discontinued products and/or enjoy older headphones, in this case one with little to no following, feel free to hunt down a set of AKG K121 Studio for yourself. Personally, I'm looking forward to finding some more appropriate pads, or buying a proper set of replacements since they're still readily available. I want to continue to use them for a long time to come. Their comfort and sound quality have ensured this headphone will remain a staple product in my personal listening lineup for a long time to come.

Thanks for reading!

- B9