Koss UR20 headphones

Review date: 23 September 2004.
Last modified 03-Dec-2011.


If you've got a few hundred US dollars to spend on a pair of headphones, it's not hard to find a great set.

What if you don't, though?

What if you don't even have $US50?

What if you've got, say, twenty bucks US?

Headphone prices start at about three US dollars a pair, these days (plus about six bucks for shipping, but you get the idea).

If you're thinking you probably don't get a whole lot of sound quality for three dollars, you're right. You do have to spend a bit more than that. Even then, cut-rate headphones, like "cut-rate software", are often not worth the small amount of money they cost. But if you hunt around, it actually is possible to buy a pair of headphones that sounds better than the ones used by many - I'd go so far as to say most - people, without spending very much money at all.

Koss UR20 headphones

Case in point.

These are Koss's UR20 Home Stereophones, which list for $US24.99 but can be yours for twenty US bucks.

Nineteen ninety-five, actually, ex shipping, from HeadRoom.

The UR20s give you a lot of headphone for your money, in gross physical terms at least. They're old school big round sealed cans, good for keeping your music on the inside and background noise on the outside, and also for making you look a bit of a tit.

Top view

The UR20 headband has an odd combination of a floppy inside cushion strap, and two springy rubber-covered wire pieces; it seems quite tough, and it's also...


...rather flexible.

Those earpieces are as big as they look. About 11cm in diameter (four and a quarter inches, say), and with an oval ear-hole in the middle that's about 7 by 5.5cm (2.75 by 2.2 inches).

The pads are only moderately thick, so your ears may touch the foam over the drivers inside, but the UR20s have quite low head-pressure and so stay comfortable. There's certainly more pad in these than there is in those Beyers I was impolite about the other day; the UR20s would probably be much the same if they clamped your head like the Beyers, but they don't.

This is a big win, right here. If you're wearing headphones for any length of time, you may well be very happy to exchange a lot of comfort for a bit of sound quality any day, and comfort in cheap sealed headphones is a rare commodity.

There's enough size adjustment in the headband for these 'phones to fit head sizes from a-bit-smaller-than-average to quite-large. If you've got a tiny elfin cranium then the UR20s may not go small enough to fit you, but you'd look like a total schmuck even if they did; big round headphones like these look dumb enough on a big head, much less a little one.

Another drawback - the way you adjust the UR20s' headband size is with a hokey slidey ratchetty arrangement that feels as cheap as it is, and usually makes you take the headphones off to adjust them. But they don't change size while they're on your head, and the mechanism doesn't seem very likely to break.

And, as I said, they're really quite comfortable. Partly because they're lighter than they look.

Koss say they weigh ten ounces (284 grams); my own weigh-in suggests that the quoted weight includes quite a lot of the cable, as well as the headphones themselves. That's a lot compared with various little portable 'phones, but when you've got a proper head-strap and big cushions around your ears, it's nothing.

In the olden days, headphones with this little density were probably made out of spit and chewing gum, but these days even cheap lightweight 'phones can be pretty tough, thanks to more advanced plastics. I doubt the UR20s have the durability of a similarly lightweight $US200 pair of Sennheisers, but I also doubt that a tenth as much money is buying you a tenth as much durability.

The UR20s have, by the way, a generous eight foot cable with rubbery insulation (not stiff 'n' shiny PVC), which enters the headphones on only one side. That's normal for more expensive headphones these days, but cheaper units still often have two-sided cords, just waiting to try to garotte you.

(Well, OK, not really; double-sided headphone cords are fragile things, usually of the figure-8 type with a tiny rubber woggle holding the top together. If someone yanks off your Y-cabled headphones and runs away behind you with them, they'll just split the cord all the way to the plug and then pop the plug apart.)

You don't, of course, get any kind of replaceable cable with the cheapo UR20s. There's no neat cable-strain-protecting plug, or even a relatively simple take-apart replacement method like these Sennheisers offer. I could see no way to get the UR20s' earpieces apart, which meant there was no way to replace the thin "pleather" vinyl fabric of the ear-pads - but a reader's informed me that there are actually three screws hidden under the ear cushions, and that Koss sell replacement cushions for five bucks.

Of course, given that the headphones only cost $US20 in the first place, it ain't too painful if you fracture the cable or otherwise find yourself needing to buy a whole new set of headphones.

The UR20 cable terminates in an eighth-inch stereo plug, as used by computers and most portable audio gear, and you also get the usual eighth-to-quarter-inch adapter, so you can plug your UR20s into the standard hi-fi system headphone socket. I'm not sure why headphones always come with these things. It's my belief that tiny quantum imbalances in the underlying structure of the universe cause eighth-to-quarter adapters to pop spontaneously into existence near all kinds of audio gear, so that any stereo system that's been sitting undisturbed for a few years will have at least one adapter hiding between two components, along with the manual for a 1983 cassette deck that you can't remember ever owning.

The UR20s also, by the way, have only 32 ohm impedance, which is important when you want to run headphones from equipment with weedy headphone outputs. The crummy headphone sockets in most home and portable stereo gear can't deliver a whole lot of power (by headphone standards - most headphones need a fraction of one per cent of the power of a loudspeaker), and often have serious voltage and current limits, too.

A strong headphone amp, such as you'll get in some quality hi-fi gear, and in pretty much any dedicated headphone amplifier, can drive all but the very strangest headphones as loud as anyone needs. If you've got headphones with very high impedance, though, you'll need a lot more output voltage to drive them to reasonable volume. More than a few high-end headphones have 600 ohm impedance, for instance; most headphone sockets can't get much volume out of those at all.

Voltage equals current times resistance (impedance is the more complex AC incarnation of resistance, but the simple DC version will do for now, and reduce the number of readers' heads that go round and round), and power equals voltage times current. So to drive a 32 ohm headphone transducer to, say, five milliwatts (mW; 0.005 watts), you need 0.4 volts. That'll result in 12.5 milliamps (mA; 0.0125 amps) of current flowing (as long, once again, as you ignore the Nasty Math that's involved in real world multi-frequency AC power calculations, and also as long as you remember your algebra. Otherwise, the numbers may turn out quite differently).

Step up to 600 ohms, and now five milliwatts requires 1.73 volts, with less than three milliamps of current flowing.

If the 600 ohm headphones are much more efficient than the 32 ohm ones (efficiency is the amount of noise you get per milliwatt; the UR20s are rated at a better-than-OK 97dB from one milliwatt input) then you'll be able to play 'em pretty loud even if your headphone output only goes up to 1.5 volts, but if the efficiency figures are much the same (as they often are, these days) then the 32 ohm 'phones will play considerably louder from a voltage-restricted headphone output.

12.5 milliamps isn't a great deal to ask for from practically any headphone socket, but more than 1.5 volts may well be; small battery powered devices, in particular, commonly don't go that high, at least not without nasty distortion. For them, low impedance headphones are definitely the way to go, particularly if you're buying at the bargain end of the market and so even a cheap add-on headphone amplifier is totally not an option.


So the UR20s avoid a lot of the pitfalls of cheap headphones. Apart from the impedance thing, they're not made out of stale bread, they're comfortable, and they look... well, there are some very expensive things that look worse, OK?

The last hurdle cheap headphones have to clear, of course, is their well-established propensity to sound like a transistor radio hidden in a filing cabinet.

I'm happy to say that the UR20s actually sound pretty good. Not great, but good enough. I listened to this, I listened to that, I listened to the very definite other, and my one-word evaluation of the UR20 sound is "inoffensive".

It wasn't difficult to tell that I wasn't listening to a top-class set of headphones, but the UR20s' defects are, as far as I'm concerned, not a big deal.

Cheap sealed 'phones often have a big ol' hump in their bass response. Like "bassy" boom box and mini-system speakers, the "one note bass" tuning gives a superficial impression of good low end response, but really you're just getting a buzzy slurry at the bottom end. Even high school kids have a good chance of preferring the sound of a couple of quality budget bookshelf speakers over a stereotypical ludicrous boom box, if given the chance to hear the difference.

The UR20s have reasonably flat bass response. They don't just play one farting-tuba note that overwhelms everything else below 500 Hertz.

They do, however, go respectably low. Koss quote 30-20,000Hz response for them. Every set of cheap headphones has specs like these (actually, the manufacturers usually throw all plausibility to the wind and quote 20-20,000Hz, or even more), but amazingly enough, the UR20 specs seem to be more or less honest - at the low end, anyway.

All sealed headphones also, by their nature, have good isolation (blocking of outside noise). The light head-pressure of the UR20s means they don't seal very well to your head (well, if it's anything like mine, at any rate), so they're not nearly as isolating as most sealed 'phones (like these, for instance). But they're still much better at intercepting the noise of an office, computer room or bus than any open headphones. I think the more-comfort, less-isolation trade-off is a perfectly acceptable one.

HeadRoom's tests of the UR20s turned up, unsurprisingly, a frequency response plot that's up and down like an Internet stock. There's a big difference between the channels, too, the reality of which I'm not so sure about; HeadRoom's test gear beats the heck out of my cruddy SPL meter, but they often find strangely large differences between left and right, even for expensive headphones.

(Some time after this review went up, Headroom revised the UR20 graph to have only one line, not two oddly different ones.)

Pretend the two channels line up with each other, and you see real response down to, well, maybe 50Hz; not as good as was advertised (30Hz is actually at -20dB or something, which is uselessly weak), but still not terrible.

And, despite all the line-wiggling, there's really not that much in the way of dreadful resonance effects. A couple of reasonably mild response peaks around 500Hz and 8000Hz, and that's about it.

HeadRoom's graph shows the treble response dropping through the floor before it even gets to 10kHz (which you don't want, though you generally do want some high frequency attenuation from headphones, seeing as there's nothing between them and your ears to soak up the treble) and the UR20 treble didn't sound exactly sparkling to me, but neither was it dull and muffled. I'm inclined to suspect a little more experimental error, there.

The HeadRoom isolation plot doesn't support my subjective experience. HeadRoom reckon the UR20s do about as well as a higher-head-pressure sealed headphone like the Sennheiser HD 280 (and, of course, much better than an open headphone like the HD 555, yet much worse than canalphones like the Etymotic ER-4S). I bet the UR20s are that good if you put them on a fake-head test rig that lets them seal well all around the ear; rest the two UR20 ear-cups against each other with no head in between and, despite the fact that they'll only touch quite lightly, very little sound will escape. But they don't isolate as well on my lumpy and misshapen head. Still, I think they've got enough isolation for many people.

One thing I noticed about the UR20s' sound is that they noticeably contract the stereo field, or "soundstage".

The stereo effect depends on differences in the midrange and treble that your two ears are hearing. It doesn't matter whether that difference is a "real" reflection of what you'd actually hear if you were sitting there listening to the original performance, or whether it's entirely an artefact of the production process (as is the case with most popular music, and a surprising amount of classical stuff), or whether it's been generated on the fly (as is the case with positional audio in games); if there's the right amount of attenuation and crosstalk and phase delay at the right frequencies, you get the stereo effect.

Headphones with less-than-perfectly-faithful reproduction qualities, like the UR20s, mess up the finer points of the stereo illusion, and make the result sound closer to mono. The UR20s obviously have a much smaller stereo field than my usual Sennheiser HD 590 'phones, and than all of the other, more expensive headphones I've reviewed (well, not counting these).

This isn't to say they make a stereo signal actually sound like mono. The stereo's still very obviously there. It's just compressed. I found rather less reason to use the crossover processor switch on my Total BitHead amp when I tried the UR20s through it.

You can, of course, expand stereo quite successfully these days, using hardware or various pieces of software. If you think you can sound-process cheap headphones into expensive ones, though, I'm afraid your hopes will be dashed.


I'm sure there are plenty of audiophiles out there who'd take strong exception to my saying the UR20s sound "inoffensive".

To some people, the quite obviously coloured frequency response and fairly crummy stereo of headphones like these are very offensive indeed. If eating supermarket-brand corn flakes for breakfast, lunch and dinner for a few weeks is what you have to do to be able to afford a more musical set of cans (like these, say), then that, they'd say, is simply what must be done.

And, I must repeat, the UR20s look pretty darn goofy. I don't really care, but my girlfriend made clear that they are as unsuitable to be seen in as certain not-anything-like-as-cool-as-people-outside-Australia-seem-to-think footwear.

But if you're a starving student who gets to enjoy an hour on the train to and from school every day, and you're looking for comfy, decent-sounding, budget 'phones to match your $20 portable CD player, and you don't give very much of a toss what those headphones look like, then you could do a very great deal worse than get a set of UR20s.

Likewise, if you're looking for a pair of headphones for use at LAN parties, gaming venues, offices populated with light-fingered co-workers, and similar perilous places, the UR20s will block a bit of the background noise, and they won't squish your head, and they'll save you from catching ear syphilis from fetid pairs of Internet café headphones, and they'll sound about as good as you'll need, under the circumstances. And if they get broken, lost or stolen, then, well, big deal.

If you can afford a hard disk MP3 player, or even a nifty MP3 CD player, or if you're just serious about your music, then you should get better headphones than these for a bit, or a lot, more money. These sealed Sennheisers, these mighty Beyers, some deliberately bass-boosted mid-sized 'phones, some ear-invading Etymotics; the list goes on.

In the cheap and cheerful category, though, the UR20s get a Recommended from me.

Review headphones kindly provided by HeadRoom.

HeadRoom's page for the UR20s

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