Excellent summer headphones: Koss Porta Pro

Author: Sword of Damocles

Information:

• Publication year: 1984
• Price: 30–40 €
• Structure: Open, on-ear
• Dynamic driver: 32 mm
• Impedance: 60 ohm
• Sensitivity: 101 dB/mW
• Weight: 72 g
• Connector type: Fixed cable, non-detachable
• Cable: 1.2 meter long cable with a 3.5 mm connector
• Included: carrying pouch
• Warranty: apparently still a lifetime warranty

Review sample: Self-purchased product

Summer heat is an unpleasant time for headphone enthusiasts, because larger headphones and leather earpads start to make you sweat even with slightly longer use. However, there are also comfortable headphones for summer listening sessions, such as the compact Koss Porta Pro (link to the manufacturer's product page). The headphones might look like ridiculous flimsy things at first glance, but they managed to surprise me not only with their comfort but also with their sound quality. That's why I'm writing a short article about them.

Released in 1984, the Porta Pro has been a kind of perennial favorite for several decades, and it is still sold almost everywhere for under 40 euros. I had not owned these headphones before, but I finally got to fill a gap in my knowledge when I stumbled upon a pair for 10 euros. So far, Kuulokenurkka has mainly reviewed more expensive headphones, so it's nice to occasionally come back down to earth by looking at more affordable products.

There are several different models of the Koss Porta Pro available, which differ mainly in their color and some functionalities. For example, the cable of some models includes a microphone for calls and buttons for volume control. The latest Utility model, on the other hand, can be listened to via a USB connector (this would, of course, also be possible with a 3.5 mm -> USB-C adapter). There's even a wireless Bluetooth model of the Porta Pro. My own headphones are called Red Hot 2.0, so their design features red details, unlike the basic model. The cable, however, has no additional features.

Structure and comfort

The Porta Pro is a compact on-ear headphone with no superfluous elements in its design. The headphones feel flimsy in hand, and they rattle and clatter when shaken. However, the advantage of the minimalist design is the almost negligible weight of 72 grams, so the headband, for example, doesn't need any padding at all.

A thin metal headband supports two small dynamic drivers, which are attached with a ball joint to the surrounding plastic structure – the headphones do not have traditional cups. The drivers pivot on the earlobes to a suitable angle, so they do not feel uncomfortable despite the thin ear pads.

The Porta Pro is not actually a traditional on-ear model, as it sits closer to the ears rather than directly on them. Most of the headband's clamping force is directed to small pad sections that rest above the ears against the head. If too much pressure still forms on the earlobes, the headphones” ”cups" can be turned slightly further away from the ears using the three-stage comfortZone adjustment mechanism. On my head, the Porta Pro feels comfortable and unobtrusive.

The height of the headband is adjusted by pulling the two plastic parts on the top of the head towards or away from each other. In my opinion, the headphones are quite difficult to put on, as the pre-adjusted height easily slips into the wrong position at the same time. For this reason, it is easiest to leave the height at the maximum position initially, after which it can be adjusted to fit with the headphones on. In this case, however, hair tends to get caught between the two metal parts of the headband, which becomes apparent as broken hairs at the latest when taking the headphones off. Using the Porta Pro therefore unusually requires a bit of practice at first.

The listening experience with these headphones is completely open, as even the smallest ambient sounds are still audible. Sound also leaks outwards from the headphones, but thanks to the small drivers, I believe the Porta Pro can be used at moderate volumes in public places – as many have done for the past 38 years. The headphones are also well-suited for mobile use because they can be folded for transport. When the drivers are turned towards the center of the headband, the bottom edge of the structure can be fastened together with a metal hook.

The versatile use of the traditional Porta Pro is currently hampered by the fact that few phones still have a headphone jack. My headphone model has a 1.2-meter long fixed cable with a 3.5 mm connector, so it requires either a headphone jack or a USB adapter. The cable attached directly to the drivers is thin, so the connection point is prone to breaking. However, I understand that Koss still offers a lifetime warranty for the Porta Pro, so the headphones can be replaced with new ones if they break.

Sound quality

I have listened to the Porta Pro sporadically on many different devices, from a laptop's headphone jack all the way to a 2000 euro Schiit Audio Bifrost 2 & Burson Audio Soloist 3X Performance device combination. I even managed to get fairly reliable frequency response measurements from the headphones with a MiniDSP EARS device.

Frequency response:

Easily digestible sound

The popularity of the Porta Pro is easy to understand immediately upon listening to it. The headphones have a pleasant (even slightly emphasized) bass and pleasantly warm and clear mid-frequencies. There is also some separation in the reproduction, and the soundstage is not oppressively small. The dark and softly reproduced treble ultimately leaves the most to be desired, but on the other hand, the headphones are always effortless to listen to. The presentation is overall natural and easily digestible, and there are no major oddities in the sound. In my opinion, the sound quality would be acceptable as such even for more expensive headphones, so the Porta Pro offers excellent value for money.

Bass:

Despite the drivers sitting on the ears (must be positioned precisely on the ears), the headphones have an astonishingly fun and punchy bass reproduction, which is a result of emphasized mid-bass. However, the emphasis is not over-the-top for my taste, as the bass remains controlled. The quality and detail of the bass reproduction are not inherently memorable, but perfectly sufficient in the sub-100 euro price range.

Sub-bass in Porta Pro remains lacking, but not worse than, for example, the Sennheiser HD600 series. The bass reproduction is actually, as a whole, more engaging than in the HD600 model, making listening to pop music with Porta Pro more fun. The headphones also tolerate a moderate boost of sub-bass through equalization.

Mid-frequencies:

I particularly like Porta Pro's mid-frequencies because they have a pleasant warmth at lower frequencies and enough energy at higher frequencies to keep the reproduction clear. The mid-frequencies are also very even, as there are no sudden boosts or dips. This gives the sound a lot in common stylistically with the Sennheiser HD650, with the difference that the Porta Pro sounds more distant. Sennheiser's HD600 series brings the sound intimately close to the listener, whereas the Porta Pro keeps it further away due to its attenuated presence region.

The dip is clearly noticeable when listening, as it pulls the sound with it as if into depth. However, this simultaneously creates more space in the soundstage, so I think there is also some benefit to the end result in headphones like the Porta Pro. The dip does not significantly bother less critical listening, as the headphones are not particularly detailed anyway. However, if equalization is possible, the 4–5 kHz range should be adjusted a few decibels louder, as it brings more life to the sound.

Treble:

Porta Pro's treble is very dark and relaxed, but it is still audible up to the very highest frequencies. MiniDSP EARS measures a clear boost in the frequency response between 5–6 kHz largely because the surrounding frequencies are reproduced significantly quieter. The shape of the frequency response is completely correct, but the lower treble actually sounds more normal than boosted. The upper treble, on the other hand, is reproduced so calmly that high sounds hardly draw any attention when listening. This style is well suited for relaxed listening, while those who desire a more energetic reproduction can freely equalize the treble 5 decibels louder from 6 kHz upwards. After this, the Porta Pro sounds excellent even when evaluated a bit more critically.

Other observations:

It is unreasonable to expect technically excellent headphones for under 50 euros, so Porta Pro's mediocrity by most metrics is not surprising in that sense. However, I have recently become accustomed to too much good, so with a less critical mind, the headphones don't sound bad at all, and it's not easy to find anything to complain about considering their affordable price. I can't actually name significantly better-sounding 40-euro headphones offhand – such would likely be found among in-ear headphones, but they are their own product category.

Porta Pro's sound has some separation, so listening to it is interesting enough even after getting used to better headphones. The headphones are very pleasant to listen to, focusing solely on music, so the somewhat soft and rounded sound ultimately doesn't matter much. With a larger sum of money, you get better, but on the other hand, the additional benefit gained starts to decrease very quickly. For example, 2000–3000 euro headphones rarely surprise, as they are expected to sound excellent. The sound quality of the Koss Porta Pro, costing under 40 euros, on the other hand, leaves an extremely positive impression for its price.

Confirmation

Porta Pro doesn't strictly need a separate amplifier, but its use is versatile thanks to its 60-ohm impedance. Since the headphones' sensitivity is also not excessively high, there is enough headroom for amplifier volume adjustment. Porta Pro is also quite immune to background noise. For example, my Burson Audio Soloist 3XP hisses somewhat with highly sensitive headphones, but no background noise is transmitted to the Porta Pro.

It is also possible to listen to the headphones with a tube amplifier with a slightly higher output impedance without the low frequencies becoming overemphasized. Although the situation was comical, I tried the Porta Pro with my Tor Audio Roger tube amplifier. The situation became even more interesting because the headphones sounded fantastically good, and they brought out the best qualities of the tubes. I wish headphone hobbies would encounter such fun surprises more often!

Popular Yaxi pads (12 €)

Japanese Yaxi earpads, costing around 12 euros, are generally recommended for Koss Porta Pro (link to manufacturer's page), which are described as further improving both comfort and sound quality. I wanted to verify this myself, so I ordered the earpads from Amazon Japan. They could have also been obtained from Europe, but shipping costs to Finland would have been unreasonably high compared to the affordable price of the earpads. The earpads are available in several different colors, making it possible to personalize the look of the headphones with them.

The thicker foam of the earpads feels pleasant against the earlobes, but at the same time, the headphones become purely on-ear models unless the ”cups” are turned slightly outwards by changing the comfortZone setting. After this, even smaller earpads reach the head, and the Porta Pro becomes even more comfortable than with its standard earpads.

Frequency response: standard earpads (red) and Yaxi earpads (white)

Yaxi pads make the Porta Pro sound clearer and fresher by boosting both the upper mid-frequencies and the treble. The high frequencies are no longer dark, but come quite to the forefront while still being comfortably listenable. In my opinion, the reproduction has just the right amount of sparkle and airiness, so the Porta Pro sounds more comprehensive – and musical details also come out better.

The end result, at a total price of about 50 euros, is so incredible that one would want to start putting the headphones on others' ears. I would argue that many unaware of the affordable price might imagine them costing over 200 euros based on the sound quality. Yaxi pads get a strong recommendation from me!

Summary

Thanks to its lightweight and sweat-free design, the Koss Porta Pro is an excellent summer headphone, in addition to sounding good. Music always reproduces naturally and effortlessly – many even more expensive headphones do not have such successful mid-frequency tuning. The Porta Pro's fun bass reproduction and calmly reproduced high frequencies are suitable for relaxed listening moments. The headphones are not intended for more critical listening, unless Yaxi pads are acquired for them, which significantly improve the reproduction of higher frequencies.

Even as they are, the headphones offer, in my opinion, unbeatable sound quality for their price of about 35 euros, which would be quite comparable in higher price ranges. The Porta Pro is not even Koss's only proven affordable headphone model, as KSC75 clip-on headphones are generally considered even better (though they have weaker bass reproduction). Also, the slightly more traditional KPH30 and KPH40 models are considered good alternatives by many for those who want to enjoy the highest possible sound quality for under 50 euros.

There are still a huge number of better headphones in the world, but few of them exceed the expectations set by their price as clearly as the sympathetic Porta Pro. Getting good sound quality out of a modest-looking product is extremely fun and rewarding, so every listening session brings a smile to my face. The headphone hobby doesn't always have to be expensive, because excellent products can also be found in affordable price ranges.

Pros and cons:

+ Suitable frequency response for relaxed listening
+ Hauska bassontoisto
+ Pleasant and clear mid-frequencies
+ Comfort is good thanks to the lightweight design
+ Can be folded for transport
+ Any device with a headphone jack is sufficient as an amplifier
+ Low price
+ Lifetime warranty
+ The sound can be made even better with affordable Yaxi pads

-/+ Technical performance is mediocre on a broader scale, but good, if not excellent, in the under 50 euro price range

– Higher frequencies lack energy, so the sound is dark in style
– The sound remains somewhat distant due to the attenuated presence region
– The headphones are quite difficult to put on the head
– Hair gets caught in the headband when adjusting its height
– The durability of the structure does not inspire confidence