(Last Updated On: March 5, 2021)

The awkward Koss middle child struggles to stand out from their siblings.

I purchased the Koss KSC35 Wireless Ear Clips from Amazon.

How does Koss do it? I can think of very few other tech companies releasing products designed decades ago, which have remained essentially unchanged, and that continue to attract new customers, involve the modification community, and excite the enthusiasts. They must have a secret recipe of herbs and spices going on to maintain their loyal following, year over year.

To be fair, Grado and Fostex also seem to have figured out the ingredients in this secret sauce of longevity and success.

Well, Koss does have a couple of essential components in their favor. Their products are often bargain-priced (below $100). Most of them come with a lifetime warranty (something almost unheard of in the audio industry). Oh, and they sound good. In fact, often extraordinarily good for their price point.

The Koss KSC35 Wireless Ear Clips.

Koss KSC35 Wireless

"Regardless of price, they sound good. And they sound pretty great for their price point. They don’t excel at any one thing, but do most everything well. This family of headphones (all sharing the same driver) are known as excellent do-it-all, jack-of-all-trades for valid reasons. They are sonically well balanced. The KSC35 sound natural, open, and controlled. They have a smooth presentation that is fun and non-fatiguing to listen to. The lack of glaring imperfections is what defines their sound."

Pros:

  • »Reasonable price for Bluetooth
  • »Shares the same driver and basic sound of the Porta Pro
  • »Light weight
  • »Good for outdoor activities allowing for hearing external sounds
  • »Ear clips do a decent job staying in place

Cons:

  • »Limited battery life
  • »Only a 1-year warranty
  • »Not the highest build quality
  • »Inflexible plastic ear clips can become uncomfortable
  • »Only Bluetooth SBC codec
  • »Not the best value in the Koss headphone lineup

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In the ’80s, Koss struck gold with a particular driver design. This unique 35mm, 60ohm driver became the heart of their iconic Porta Pro headphones. This driver also shows up in other Koss headphones, including the Sporta Pro, KPH30i, and the KSC35. A titanium-coated version is used in the UR40, KTXPro1, and KSC75.

It is essential to differentiate KSC from KFC. A KFC35 is likely a large paper bucket filled with 35 pieces of fried chicken. They may be delicious but are not great sounding. On the other hand, the KSC headphone lineup includes the delectable 35, 50 (now discontinued), 55 (now discontinued), and 75.

The KSC35 were originally released in January 1995 and have come and gone over the years (they were discontinued around 2000 but came back in the mid-2000s). What hasn’t changed is that they provide terrific value for their modest price. Inexpensive but excellent is always a winning combination. Today, we’re exploring the most recent 2020 release of the Bluetooth wireless version of the KSC35.

Keep in mind that the Bluetooth version simply is a cable change to this 26-year-old design.

The KSC35 were reportedly the first ear clip style headphone. Ear clips are a fairly unusual style for portable headphones, especially in this time of IEM dominance. However, many companies still offer one or two clip-on models, including Audio Technica, Philips, and Audeze.

The black plastic KSC35 ear clip doesn't look very comfortable.
The black plastic KSC35 ear clip doesn’t look very comfortable.

While the KSC35 clips don’t appear comfortable or particularly well made to my eyes, clearly, they must offer something special. Let’s dive in and find out why these headphones still have their fans after so many years!

Company Overview

Headquartered in Milwaukee, WI, Koss Corporation is the quintessential classic American headphone company. John Koss and his partner Martin Lange JR. developed the “world’s first stereophones, the SP/3” in 1958. The SP/3 were intended to be an accessory for their new stereo record player, but stole the spotlight.

“Listeners of the era were experiencing stereo headphones for their first time. People were won over by this revolution in personal listening. It was around this same time that Koss coined the phrase “Hearing is Believing”.” – Koss

Koss eventually branched out into creating home theaters, DVD players, portable media players (MP3), tabletop stereo systems, and boom boxes but has since closed the “Koss Electronics” line. Koss Corporation now focuses on what they do best, manufacturing both dynamic and electrostatic headphones and microphones.

The KSC35 drivers.
The KSC35 drivers.

Technical Specifications

  • Form: Ear clip portable Bluetooth headphones
  • Drivers: 35mm Dynamic driver
  • Impedance (Ohm): 60ohm
  • Sensitivity (dB): 101 dB SPL/1mW
  • Frequency Response (Hz): 15 Hz – 25 kHz
  • Removable Cable: N
  • Bluetooth Audio Codec: SBC
  • Battery Life (hrs): 6
  • True Wireless: N
  • Bluetooth Version: 4.2
  • Mic: Y
  • Weight (g): 33
  • Warranty: 1-Year limited

Packaging

Koss uses a standard white cardboard box design with red highlights for most of their products. The front of the box has a conventional high-resolution photo, while the back shows the driver’s construction and instructions for the inline remote. The packaging design is immediately recognizable as Koss and is clean and classy.

All the Koss packaging shares this style.
All the Koss packaging shares this style.

Inside, the KSC35 are nestled in dense back foam with the inline remote displayed between the earpieces.

In the box

  • KSC35 Wireless Ear Clips
  • Micro USB charging cable
  • Instruction manual
  • Pleather storage bag
The included accessories are rather sparse.
The included accessories are rather sparse.

Cable

Although “wireless,” the KSC35 do have a ±53cm grey rubber cable, with a 5 cm long inline remote control containing a microphone and the battery. Also included on the cable is a small chin slider. The cable is thin, has no strain relief at the ear cup connection, and overall isn’t very confidence-inspiring as to its longevity.

The remote control is a standard 3-button affair, with grey rubber buttons for volume and track skip surrounding the play/pause/power/pairing center button. The red/blue LED is thankfully tiny and not overly bright (unlike the one in the wireless Porta Pro I reviewed). Charging is done via a micro USB port on the bottom of the remote control module.

Design

The KSC35 were designed two and a half decades ago using a driver design from ten years earlier. And they look the part. Retro-cool or just retro? I’ve got a soft spot in my heart for the classic Koss look, but whether you like Walkman tape players’ aesthetics and portable CD players is a personal preference.

The retro style of the KSC35 may not suit all tastes.
The retro style of the KSC35 may not suit all tastes.

Generally speaking, the KSC35 are entirely made of plastic and feel inexpensive. I forgive you for assuming that they are terribly fragile if you’ve never owned a Koss headphone before. However, I’ve had Porta Pro headphones last for decades. While certainly far from indestructible, they are more robust than they seem, although I would suggest using a protective storage case if you are going to backpack the KSC35.

The stock Koss foams are just (and let me stress ‘just’) thick enough for comfort. The first thing to do if you own a pair of these headphones is to visit the Yaxi website and order a pair of their Porta Pro foam pads in your favorite color.
Comparison between the stock ear pad (front) and the Yaxi pad (rear).
Comparison between the stock ear pad (front) and the Yaxi pad (rear).

The KSC35 define open-back, on-ear headphones. Perched daintily upon your ears, they leak about as much sound outwards as inwards. Additionally, they allow plenty of environmental noise to reach the listener, although I find this beneficial when using the KSC35 for walks or other outdoor activities.

Comfort

The plastic ear clips are fairly rigid and non-adjustable. So, comfort is a bit of a crapshoot. You can rotate the clips around on your ears, but if your particular ear shape isn’t a perfect fit, you may struggle to wear the KSC35 for long periods. Surprisingly, the clips hold the KSC35 securely on the ears and stay in place for most light activities, including jogging.

All that plastic pays off with a comfortable, light weight.

Comparison of the KSC35 ear clip (front) and the KSC75 (rear).
Comparison of the KSC35 ear clip (front) and the KSC75 (rear).

While are more robust, the similar KSC75 sport thicker rubber-coated metal clips, which are heavier and somehow feel less secure on my ears. Note that the Porta Pro and Sporta Pro headbands, or the KSC75 ear clips, can all be swapped with the KSC35’s clips. The drivers simply snap in and out of the band or clips. I primarily use the KSC35 with Yaxi ear pads and a very inexpensive (less than $5) Parts Express headband.

This KSC35 review is the first step in a larger arc of reviews, including the KSC75, Porta Pro, and KPH30i, culminating in an article that will detail popular user modifications, including pictures and measurements.
The KSC35 sporting Yaxi pads and the Parts Express headband.
The KSC35 sporting Yaxi pads and the Parts Express headband.

Putting on the KSC35

  1. Hold a driver slightly above the appropriate ear with an index finger and thumb.
  2. Slide the driver down until the top of your ear is between the clip and the ear pad.
  3. Push the bottom end of the ear clip inwards with your thumb and position it under your ear lobe.

Internals

The infamous 35mm Koss driver used in so many of their headphones is what makes it all work so well and sound so good.

If you peek inside the vents you can catch a glimpse of the famous Koss driver.
If you peek inside the vents you can catch a glimpse of the famous Koss driver.

According to Koss, the “computer-optimized neodymium, iron, and boron rare-earth magnet structures deliver amazing clarity at any volume” and the “oxygen-free copper voice coils improve signal transmission and conduction for cleaner, clearer sound.”

All I can say is that if ever a design has stood the test of time and proven itself, over and over again, it’s this driver. It’s a standard dynamic driver, albeit somewhat unusual these days as it has a slightly high, 60ohm impedance.

While a touch more difficult to drive than ultra-low impedance models, the KSC35 have a 101 dB SPL/1mW sensitivity, so they work fine with the tiny Bluetooth dongle amplifier. Plenty of power on hand to get uncomfortably loud if desired.

Bluetooth

The Bluetooth module is version 4.2 and only supports the basic SBC codec with all the latency and limited dynamics inherent in that standard. Let’s face it. These aren’t analytical audiophile headphones designed for critical listening. With that expectation firmly in mind, the Bluetooth module works absolutely fine for active or background listening, which is the primary intent for the KSC35 headphones.

The inline remote with bluetooth receiver and internal battery is basic but functional. The LED is discrete, unlike the Porta Pro Wireless.
The inline remote with bluetooth receiver and internal battery is basic but functional. The LED is discrete, unlike the Porta Pro Wireless.

The rechargeable lithium-ion battery life is middling at 6 hours (the wireless Porta Pro lasts 12+ hours and supports aptX codecs). The SBC35 will not work while charging.

KSC35 Sound

Let’s make sure we are on the same page. The KSC35 are inexpensive Bluetooth headphones. As such, they must be evaluated at this price point, with some perspective on their overall sound quality.

The KSC35 are not the most detailed or transparent headphones. They do not have the most extensive soundstage or imaging. Their resolution is fair. Their extension is just ok.

So why in the heck do people like these headphones so much?

The KSC35 sound good. And that’s the point. Regardless of price, they sound good. And they sound pretty great for their price point. They don’t excel at any one thing, but do most everything well. This family of headphones (all sharing the same driver) are known as excellent do-it-all, jack-of-all-trades for valid reasons.

They are sonically well balanced. The KSC35 sound natural, open, and controlled. They have a smooth presentation that is fun and non-fatiguing to listen to. The lack of glaring imperfections is what defines their sound.

The frequency response graph for the KSC35.
The frequency response graph for the KSC35.

Bass

While slightly less bass-heavy than their Porta Pro brethren (likely due to the looser ear clip wearing style), the KSC35 bass response is remarkably satisfying. Certainly, they have more mid-bass focus than sub-bass, but they avoid excessive bloom or muddiness. Do not expect bass response to satisfy most bass-heads.

Midrange

The midrange is defined by the warmth created by a bump in the upper bass and lower midrange frequencies. This tends to add a bit of body to male vocals and to the music. The overall sound is relaxed and smooth, tending towards a darker sound signature.

Treble

The KSC35 treble response is tame and controlled. The high frequencies avoid excessive brilliance and energy but do remain quite articulate and open sounding. The SBC Bluetooth codec has an upper-frequency roll-off, which is a fine match to the KSC35 sound signature. Nothing much is lost in the mix, and a relaxed and non-fatiguing sound signature is the result.

Comparisons

With the KSC35, KPH30i, Porta Pro, and KSC75 headphones all sharing the same driver (the KSC75 has the titanium coated version), and with all four currently on hand, clearly, I need to compare them. As separate reviews for all these models are forthcoming, let me try to summarize it all into a quick reference chart.

HeadphoneSound QualityBluetoothComfortBuild QualityValue
KSC35 Wireless Ear Clips32333
KSC75 Ear Clips4 432
Porta Pro Wireless21114
KPH30i1 221
The chart above shows my relative rankings per category. 1 is highest and 4 is lowest. These ratings are only in reference to each other.

All these headphones are on-ear, and as such, are extremely dependent on clamping force and wearing position for their sound quality.

What is obvious from the chart above is that I rate the Porta Pro (wired and wireless versions) and the KPH30i above the KSC35 and KSC75 in basically all categories. Full disclosure, I’ve owned the Porta Pros for decades and love them. There are currently 4 pairs of them kicking around my home, and my wife has permanently adopted the wireless Porta Pros.

I’ve run into no issues so far, but many folks report that the all-plastic KPH30i can be easily broken.
Frequency response graph comparing the Koss Porta Pro Black, the KSC35 Bluetooth, and KSC75.
Frequency response graph comparing the Koss Porta Pro Black, the KSC35 Bluetooth, and KSC75.

I find the standard headband design more comfortable than ear clips in all cases. The Porta Pro are by far the best built and strongest feeling of all the options. The Porta Pro Bluetooth, although more expensive, are notably better than the KSC35 with double the battery life and higher quality codec support.

The sound quality rating is a tough one to quantify. The differences are pretty minimal, especially between the Porta Pro, KPH30i and the KSC35. Most of the difference seems to be in the low-end, with the Porta Pro the most bass heavy and the KSC75 by far the lightest. The KSC75 sound is the brightest of the bunch, while the KPH30i are more mid-range focused.

Sound quality is so much in the preferences of the ear of the listener. If you prefer brighter sounding headphones, the KSC75 may appeal the most to you.

The KSC35 Wireless are the odd middle child. While they never top the pack, I prefer them to the KSC75 in most cases. They sound basically like the Porta Pro, if a bit less bass-heavy due to their ear clip wearing style affecting the position and clamp force.

The 1.5x more expensive wireless Porta Pros offer perhaps the least value per dollar for headphones with the same driver as the others. Yet, with all things considered, they are still my top recommendation and favorite of them all. The wired version varies in price depending on color and cable options and are likely the best general value for those not requiring a wireless connection.

Where to Buy

Conclusion

The wired version of the KSC35 is currently only a little cheaper than the wireless version. This is very unlike the $30-$50 difference between the wired and wireless Porta Pro options. This almost identical pricing makes the KSC35 a tough recommendation when compared to their more competitively priced Koss brothers and sisters.

Like 'em or not, the KSC35 are an enduring presence in the portable headphone scene.
Like ’em or not, the KSC35 are an enduring presence in the portable headphone scene.

Since the KSC35 share the magic Koss driver, they are bound to be decent headphones. But they just aren’t special enough to stand out from their siblings. I’d recommend purchasing the far better built wired Porta Pro for a similar sound at around the same price. For their bargain price, the KPH30i is the clear winner. If you want a truly different sound, then the brighter and more resolving KSC75 is the way to go.

Are the KSC35 good? Absolutely. Are they going to be far better when modified with an over-ear headband, with Yaxi ear pads, and detachable MMCX connectors? I guess we will find out in the upcoming Koss modification article!