Product Description

Unique earbud design directs sound into the ear canal for deep bass and extended frequency performance. Specialty ear cushion material forms slowly in the ear canal to provide a custom fit and maximum isolation. Straight, dual entry 4 foot cord. Frequency Response: 10-20,000Hz.

Product Details

• Brand: Koss
• Model: 156407
• Released on: 1999-02-02
• Original language: English
• Dimensions: 1.00" h x 4.00" w x 6.00" l, .31 pounds

Features

• 16 to 23,000 Hz frequency response
• Deep bass performance
• 4-foot cord

Amazon.com Product Description
Koss's miniature portable earphone, affectionately dubbed "The Plug," makes use of an ear-cushion material (similar to that used in sound-blocking earplugs) that slowly expands in your ear canal to provide a custom fit and maximum sonic isolation from external noises. A detachable, extrawide headband makes these Koss-termed "stereophones" easy to carry or store.

For accurate sound reproduction, these earbud-style headphones are made with oxygen-free copper voice coils and neodymium iron boron magnets. You can enjoy them with either a portable or home audio device, since both 0.125-inch and 0.25-inch adapter jacks are included.

"The Plug" weighs a mere quarter ounce and has a frequency response rated at an impressive 16 to 23,000 Hz (though its unlikely you'll hear bass output anywhere close to what you'd get from a similarly rated loudspeaker!).

Impedance is 16 ohms, with less than a 0.3 percent distortion and reasonably high sensitivity of 112 dB SPL/1 mW.

Customer Reviews

Good, cheap sound solution for the traveller
NOTE: the description I saw on the Amazon page does not reflect the product I have. Above it discusses a headband and an adapter which are not part of this product. Also, the rated frequency response is 10-20k, not 16-23k. I think this is (or was) an Amazon editorial error.

My interest for this product is as a solution to listening to music, lectures, and movies while travelling, and I travel a lot. I have a set of Panosonic noise-cancelling headphones which were good (about five times more expensive than these earbuds) though bulky, but the plastic broke so they won't stay on my head now.

These earbuds are an excellent alternative to noise-cancelling headphones for the frequent traveller. I find them more comfortable for extended listening than most conventional headphones. The ability to seal out noise from the external environment is very good, and makes it possible to understand what actors are saying when watching a movie on an airplane.

The overall performance - sound quality and noise blocking - is not as good as the Bose noise cancelling headphones, but the Bose are 20 times as expensive, much less convenient to carry, and subject to damage from the rough world of the road warrior. If The Plug had an optional noise-cancelling unit (say, combined with the eq), it would be a killer combination - are you listening, Koss?).

The sound is good. Bass-heavy, to be sure; I would like them better if they had a flatter response, but the product is marketed at the portable music crowd, and many of them are looking for dramatic bass rather than golden-ears sound.
Besides, mobile sound is always a compromise, it's just a question of whether the compromise they chose works for you.

Here are some problems I've heard and the solutions:

1. "They fall out of my ear." I think an older version of this product did not come with alternative cushions; the ones I bought recently (as pictured here) came with 3 alternative cushion pairs, one of which fit well in my somewhat large ears. To make them fit well, roll the cushions in your fingers and squeeze them down, then hold them in place in your ears while they adjust the fit. Also, it is possible to fashion your own cushions (easy modification to commercially available ear plugs from pharmacy); go to google and search for "koss plug mods".

2. What about when I have to replace the cushions, they'll get waxy/dirty with use? See last sentence of #1.

3. "They sound tinny". I have a sense that the sound was tinnier on an earlier version of these earbuds, judging from comments I've read in feedback and on the koss plug mods page. The purple plugs (as opposed to the older(?) blue ones) do not sound tinny to me; they seem a bit heavy on the bass instead. Koss also makes a 3-band eq (20 dollars) for their headphones that can be used to adjust the sound some. I have an eq on order, hoping it may temper the boomy bass a bit. Of course, your player may have a way of changing the color of the sound, but my laptop does not.

4. "They're easy to lose." The price of their tiny size and negligible weight, is that you need to be careful not to lose them. I've already lost a pair. Koss also makes a carrying case which may help, or you could just put them in a 35mm film canister. But at $... a pair (compared to $... for noise-cancelling headphones) I'll just keep a spare pair around in my travelling case.

Overall I'm pleased with the price/performance tradeoff for these earbuds, and they are an essential part of my travelling kit. They sound better than any other earbuds I've used, and they remove a good bit of the ambient sound, offering more pleasure in listening. I give four stars out of five because I'd prefer a less bassy sound, though some people will really like the way they sound.

Great headphones, but ONLY the 'new ones'
Ok the first thing about this review. I have a pair of the 'new' the Plug headphones. They are not the ones pictured here. They have no mute button and are metallic silver and purple in color not blue and yellow.

Apprently KOSS got a lot of feedback from the first version, they listened, and made a much better product. The ones I have are just fantastic. Great bass, like the original, but very good mids and lows as well. They work better as isolation headphones then anything I have used before, but apprently people who are audiophiles are not that impressed. Also they have fantastic volume ability. Because they are in your ear canal I can turn my portable equipment up really loud. I don't but its nice if you want to. Music sounds great with these headphones. Frankly best headphones I have ever used, BUT I am using the NEW VERSION not the blue and yellow ones pictured here.

OK right now what to do? I would call Amazon and MAKE SURE you are getting the new version. I never used the one they have listed here but almost everywhere I looked on the net, people say the new version is MUCH BETTER...

Forced to write my own review...
I'll keep this concise and pertinent...

GOOD
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1. Very good sound (esp. for the price), just make sure you are not using any bass expansion/extension equalization. Even with old Sinatra, using my TDK Mojo's bass expansion sometimes causes distortion, simply because The Plug has exceptional low frequency response. So hip-hop obviously causes a lot of distortion w/ extra bass emphasis; I wonder if this is the 'muddiness' about which some have complained. Flat equalization (at least for bass) is a requirement for these headphones.
2. Excellent isolation and efficiency due to the foam sealing design. Just don't blow your eardrum turning the music up too loud, nor get run over by a bus 'cause you can't hear it coming!
3. Excellent overall sound quality; no tinny sound other reviewers have mentioned, unless The Plug is inserted incorrectly (ie - off-axis, or not "aimed" correctly).

BAD
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1. True, the black foamy material does not stay compressed very long, so you have to 'roll' it in your fingers then immediately put it in your ear. I could see that those with small ears may have problems fitting these properly; problem solved by retrofitting a standard foam-type earplug (as others have mentioned). Whether you would or should do this is another question. The packaging does include a few different styles of foam inserts to try; coned, cylinder, etc. After using the coned ones for a long time, I've switched to the cylinder-shaped ones, which stay in better.
2. The first pair of these I bought had uneven bass; the left earplug's bass was a lower sound pressure than the right; treble was fine. I verified this with both ears and then with a function generator. I exchanged them and the subsequent pair is perfectly balanced.
3. If The Plug is not inserted straight (not 'aimed' into your ear canal) the sound will lose its midrange (the 'tinny' thing some have mentioned). This would depends a lot on how your ears are 'designed.' I personally don't have an issue with this.

Overall, I think these earbud headphones are excellent, especially for the price.