These two cans may be one of the most pleasant, natural sounding headphone AKG has ever produced. Frankly, I haven’t heard the K601, but compared to the K701, K401, K240, K271, and even the K340, the K500 & K501 remains a long time favorite due to their natural sound. The question then becomes, why were they continued? It seems that part of the AKG corporate philosophy is to produce a great sounding headphone, then discontinue it, so that people who wants it can’t get it any longer. Pretty effective way of building a brand image. AKG: the maker of great discontinued headphones.
The K500 and the K501 is identical in shape. As a matter of fact, the housing and headband design is shared by the K400, K401, and the K301 as well. The donut shaped pads are made out of synthetic leather material, and people often upgraded the pads to either the K601 or the K701 pads. The K601’s pads are of the same shape as the K500/501, but it’s made of verlour. The K701’s pads are not perfectly round, but they have a shape that helps to put the drivers at an angle to your ears. Every one of these pads alters the sound slightly, and so it’s up to you to decide which pads suit your music best.
If the K501 is rare, the K500 is even rarer. Though I personally like the sound of the K501 better than the K500, (I’ll describe the differences a few paragraphs below), the K500 is still desirable precisely because they’re very hard to get, and the black housing to the gray headband color scheme is way cooler looking than the K501’s gray housing and black headband. Not to mention that almost every K501 that I have come across have peeling off model marking.
Before we move on to talk about the sound of the K500 and the K501, let’s talk about amplifier requirements of these two headphones. They are one of the hardest headphone to drive, next to the likes of the K340. Why? I have no idea, but the K501 are harder to drive than the K701 (75 ohms), as well as the HD650 and the HD800, and the K500 are not so far behind it in terms of amplifier requirements. Both the K500 and the K501 may be rated at 120 Ohms, but they are far more difficult to drive, than headphones with higher impedance ratings such as the HD650 (300 Ohms) and the HD800 (300 Ohms). Not only do they require a high amount of gain (roughly 25% more on the volume knob than the Sennheisers or the Hifiman HE5 Orthodynamic), but the K501 also requires quite a high amount of current. So far, the only other headphone that’s harder to drive than the K500/K501 are the K340, possibly the K1000, and some vintage orthodynamics. Some amplifiers may have enough voltage gain, and so you can get a good amount of loudness from these headphones, but that doesn’t mean that the amplifier can supply enough current for these cans.
When under current, I find the K501 to suffer more than the K500. These wonderful headphones suddenly lack bottom end impact, and I can’t help but thinking of the word “impotent cans” that can’t seem to get themselves up. The effect is more or less the same on both headphones, but is more pronounced on the K501. I really can’t give a strict rule on what amplifier specifications are need for these two, but I can tell you that the Dr. DAC Prime, the Lisa 3, the Heed Canamp, the Grace m902, the WooAudio6, and the Beta22 are some of the amps that I’ve found to work well with these cans. But please don’t conclude that you need expensive amplifiers to drive the K500/K501s, because apparently Dhani’s CMOY (on steroids, using a 19V power supply and an array of fancy opamps like Burr-Brown’s OPA552PA and Analog Devices’ ADA4627-1ARZ, AD825ARZ) did a great job on driving the K501. I really wouldn’t spend too much money on getting a premium, reference amps for these cans, but it is important that your amplifier can deliver the power needed.
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nice. it remaind me to the old days when i have K501
btw, i think you need to introduce dhani cmoy, or maybe cmoy shootout since you mentioned it on this review
Hi Mike, nice review here,
by the way do you think K501 soundstage is kinda artificial, because I ever compare it to HD600 side-by-side and K501 doesn’t really differ in soundstage wideness, the strongest difference is that K501 sound much airier (is it the right word? thinner?) than HD600, kinda like the difference between a fully stuffed room and an empty room (but not echoey),
and about the impedance factor, isn’t it the other way around? in speaker building I learned that lower impedance driver draws more current thus will need a more powerful amplifier, but again I’m no expert in this subject so CMIIW
I love my K500s, which I bought for $70(!) this year. Better then any other piece of my AKG collection.
$70 is a steal for K500s!!!!
Thanks for a very thoughtful review. I retired my K501s after 10 years of listening, during which I occasionally drifted to Grado 225s in search of more visceral bass slam, but always came back. The Grados never could equal the spaciousness or smoothness of the 501s, but I *did* miss the Grados’ bass. (I listen to jazz, electronica (house music), R&B, and small amounts of rock and classical.)
Replacing the 501’s earpads with 701 pads made a big improvement in my opinion, as the new pads helped capture what I previously had thought was “missing” bass. But the 501s remained very hard to drive, and tended to sound congested at higher volumes.
I still have my 501s, but have shifted to Shure SRH840 for my primary listening. The Shures revealed some key weaknesses in my set-up: the Grado extension cable, which I replaced with a Mogami cable; and my Rega EAR headphone amp, for which I’m shopping for a replacement. I use Naim gear, and am looking forward to hearing their HeadLine headphone amp in my system.
Once I settle on a better amp, I’ll give another listen to the 501s to see if their shortcomings have been mitigated.
I’m glad they haven’t been forgotten!
Hi Ron, the K501 is a great headphone. Why AKG discontinued it still puzzles me.
On the Grace m902 amp, the 501 finally has a proper low end impact. The amplifier requirement for the 501 is not easy, and perhaps that’s one of the reason AKG discontinued it.
I still think that the 501 is primarily a Jazz/Classical headphone though. I don’t think it has enough bass punch for R&B and Electronica/House. Don’t you think so?
The Shure (and the Grados I’ve used: the 225 and 325) are much better than the K501 for R&B and Electronica/House. The Shure also offers more inner detail, but less of a sense of spaciousness than the K501.
I have a Naim HeadLine amp and NAPSC power supply on order to try, so we’ll see what results it can get with the Shure and the AKG. I’m hoping the Naim pieces will arrive in the next couple of weeks.
Hi Ron,
I left a message on your blog.