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KOSS Porta Pro Review (On-ear Headphone)

Rate this headphone:

  • 1. Poor (headless panther)

    Votes: 14 8.4%
  • 2. Not terrible (postman panther)

    Votes: 48 28.7%
  • 3. Fine (happy panther)

    Votes: 84 50.3%
  • 4. Great (golfing panther)

    Votes: 21 12.6%

  • Total voters
    167

amirm

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This is a review and detailed measurements of the KOSS Porta Pro on-ear headphones. It was kindly purchased and donated to the forum for review. It costs US $50.
Koss Porta Pro Review On-ear Headphones.jpg

This is an ultra light headphone that folds into a very small package:

lightest on ear headphone review.png


You barely feel it on your ear and that is it. It is extremely comfortable for me.

I have fond memories of this headphone wearing on long flights to Japan when I was working for Sony in early 1990s. I remember it having a surprisingly warm sound for such a diminutive headphone.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

The cups fit my fixture's artificial ears easily although it is hard to know if they emulate how they would land on yours.

KOSS Porta Pro Measurements
Let's start with our usual frequency response measurements:
Koss Porta Pro Measurements Frequency Response On-ear Headphones.png


We see why I thought they had a warm sound due to excess energy between 70 and 400 Hz. Above that we have good compliance but then have two major troughs. Sub-bass is missing in action as one would predict. Subtracting the measurement from our target we get the relative response which I use to develop eq filters:

Koss Porta Pro Measurements relative Frequency Response On-ear Headphones.png


Drivers can't seem to handle bass well and have some acoustic anomaly around 4 kHz:
Koss Porta Pro Measurements relative distortion On-ear Headphones.png


Koss Porta Pro Measurements THD distortion On-ear Headphones.png


Impedance is variable and on the low side:

Koss Porta Pro Measurements Impedance On-ear Headphones.png


They sip power though so you should be able to drive them with most sources:

most sensitive headphone tested.png


Group delay identifies messiness around 4 kHz due to reflections:
Koss Porta Pro Measurements Group Delay On-ear Headphones.png


Koss Porta Pro Listening Tests and Equalization
The impression of upper bass comes across immediately with these headphones. It sounds a bit stuffy due to that, and lack of energy further down the frequency range. It is not too bad but clearly not what we want out of a high-fidelity headphone. A few filters perform miracles here:

Koss Porta Pro Equalization EQ On-ear Headphones.png


The sound was now more open and better balanced. I was especially impressed with some amount of spatial qualities which I did not expect to come from these small headphones. Combine with the comfort they provide, this becomes a very enjoyable headphone to listen to.

Conclusions
The Porta Pro is as classic as you can get. It is good to see that it doesn't produce crazy wrong response. It does need equalization which once deployed, produces a very nice experience. It is so good that after I took the review picture, I put them back on to listen to as I am typing this! It is a nice alternative to IEMs for those hot summer days to wear.

Without EQ, the KOSS Porta Pro doesn't get a recommendation from me. But add EQ, and it becomes recommended with a smile. :)
 

Attachments

  • Koss Porta Pro Frequency Response ASR.zip
    24.6 KB · Views: 188

sweetchaos

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To import this PEQ profile into 'Equalizer APO', use:
Preamp: -7.8 dB
Filter 1: ON PK Fc 21 Hz Gain 7.8 dB Q 1.0
Filter 2: ON PK Fc 38 Hz Gain 0.4 dB Q 3.0
Filter 3: ON PK Fc 180 Hz Gain -4.0 dB Q 2.5
Filter 4: ON PK Fc 3600 Hz Gain 6.0 dB Q 5.0
Filter 5: ON PK Fc 5253 Hz Gain -2.0 dB Q 7.0
Filter 6: ON PK Fc 7950 Hz Gain 7.0 dB Q 7.0
Otherwise, see my PEQ guide.
..................................................................................................................
For those who don't have PEQ-capable app, and want to use GEQs instead:
See my GEQ guide for 10-band, 31-band, and 127-band GEQ profiles.
 
Last edited:

bequietjk

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Joined
Jan 4, 2019
Messages
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399
I love the KSC75 and now I just might have to finally try the Porta Pro!
 

UCrazyKid

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Location
NW Chicago Suburbs
I have been a fan of the Porta Pro for decades. I have probably purchased 8 pairs and likely have 3 around right now. Often found for under $30 they are a real bargain for better than average sound at up to $200. Worth checking out.
 

ROOSKIE

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Minneapolis
I have 2 pairs.
I like to use them while walking as I can still hear some birds and hustle/bustle of life around me and they weigh nothing. (not to mention walking in the city it is nice to hear what is going on around for reasons unfortunately that are sad)
I like the sound and don't usually listen to them very loudly.
I paid under $30 for each pair - they often go on sale in USA for $25-35.
 

solderdude

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Jul 21, 2018
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Location
The Neitherlands
The PortaPro is very similar to the KPH30i (red). My preference goes to the PortaPro.
I 'modified' mine by removing the metal hook as it was always poking in my pinna. Sold it... did keep KSC35 and KSC75 (ear clips) and put KSC75 clips on the KSC35.

kph30i-vs-portapro-new.png


index.php


Getting a good seal is not a big problem fortunately.
leakage.png


Downsides:
It starts to audible distort as soon as you go above comfortable loud levels.
Pads will fall apart quite quickly.
Lacks deep bass and 'air' so treble is not refined but also not poor in quality.
Takes some time to adjust it correctly (it sits on the temple and you have to adjust the distance to your ear.
Metal hook (for transport) always poked in my pinna

upsides:
Sound one can quickly and easily adjust to.
cheap
lightweight
small
exists in various colors
Durable
sensitive (can be driven from a phone)
(limited) lifetime warranty
 
Last edited:

Doodski

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I retailed the Porta Pro starting ~1987'ish. They where ordered in the thousands at a time. Always a good mover and they sold for more than they do today. The Porta Pro came out in 1984.
 

GWolfman

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A decent surprise!

These or the cheap Sony headphones @amirm loves? $10 was it?
 

Doodski

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A decent surprise!

These or the cheap Sony headphones @amirm loves? $10 was it?
The Sony for ~$9.99
 

Maiky76

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Joined
May 28, 2020
Messages
347
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2,678
Location
French, leaving in China
This is a review and detailed measurements of the KOSS Porta Pro on-ear headphones. It was kindly purchased and donated to the forum for review. It costs US $50.
View attachment 173165
This is an ultra light headphone that folds into a very small package:

View attachment 173166

You barely feel it on your ear and that is it. It is extremely comfortable for me.

I have fond memories of this headphone wearing on long flights to Japan when I was working for Sony in early 1990s. I remember it having a surprisingly warm sound for such a diminutive headphone.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

The cups fit my fixture's artificial ears easily although it is hard to know if they emulate how they would land on yours.

KOSS Porta Pro Measurements
Let's start with our usual frequency response measurements:
View attachment 173168

We see why I thought they had a warm sound due to excess energy between 70 and 400 Hz. Above that we have good compliance but then have two major troughs. Sub-bass is missing in action as one would predict. Subtracting the measurement from our target we get the relative response which I use to develop eq filters:

View attachment 173169

Drivers can't seem to handle bass well and have some acoustic anomaly around 4 kHz:
View attachment 173170

View attachment 173171

Impedance is variable and on the low side:

View attachment 173172

They sip power though so you should be able to drive them with most sources:

View attachment 173173

Group delay identifies messiness around 4 kHz due to reflections:
View attachment 173174

Koss Porta Pro Listening Tests and Equalization
The impression of upper bass comes across immediately with these headphones. It sounds a bit stuffy due to that, and lack of energy further down the frequency range. It is not too bad but clearly not what we want out of a high-fidelity headphone. A few filters perform miracles here:

View attachment 173175

The sound was now more open and better balanced. I was especially impressed with some amount of spatial qualities which I did not expect to come from these small headphones. Combine with the comfort they provide, this becomes a very enjoyable headphone to listen to.

Conclusions
The Porta Pro is as classic as you can get. It is good to see that it doesn't produce crazy wrong response. It does need equalization which once deployed, produces a very nice experience. It is so good that after I took the review picture, I put them back on to listen to as I am typing this! It is a nice alternative to IEMs for those hot summer days to wear.

Without EQ, the KOSS Porta Pro doesn't get a recommendation from me. But add EQ, and it becomes recommended with a smile. :)

Here are some thoughts about the EQ.

Notes about the EQ design:
  • The average L/R is used to calculate the score.
  • The resolution is 12 points per octave interpolated from the raw data (provided by @amirm)
  • A Genetic Algorithm is used to optimize the EQ.
  • The EQ Score is designed to MAXIMIZE the Score WHILE fitting the Harman target curve (and other constrains) with a fixed complexity.
    This will avoid weird results if one only optimizes for the Score.
    It will probably flatten the Error regression doing so, the tonal balance should be therefore more neutral.
  • The EQs are starting point and may require tuning (certainly at LF and maybe at HF).
  • The range around and above 10kHz is usually not EQed unless smooth enough to do so.
  • I am using PEQ (PK) as from my experience the definition is more consistent across different DSP/platform implementations than shelves.
  • With some HP/amp combo, the boosts and preamp gain (loss of Dynamic range) need to be carefully considered to avoid issues with, amongst other things, too low a Max SPL or damaging your device. You have beed warned.
  • Not all units of the same product are made equal. The EQ is based on the measurements of a single unit.
  • YMMV with regards to the very unit you are trying this EQ on.
  • I sometimes use variations of the Harman curve for some reasons. See rational here: https://www.audiosciencereview.com/...pro-review-headphone.28244/page-5#post-989169 NOTE: the score then calculated is not comparable to the scores derived from the default Harman target curve if not otherwise noted.
Good L/R match.

I have generated one EQ, the APO config file is attached.
The HF troughs are severely decreasing the score.
Quite a bit of boost on either end of the spectrum, beware and careful.

The score with EQ could be higher if the LF is not fully compensated as the regression error becomes flatter
But that's cheating(?)...
Filter 1: ON PK Fc 24.98 Hz Gain 8.32 dB Q 0.65 - >Filter 1: ON PK Fc 24.98 Hz Gain 3.32 dB Q 0.65 yields a score of 84.8

Score no EQ: 25.4
Score Armirm: 48.0
Score with EQ: 80.2

Code:
Koss Porta Pro APO EQ [email protected] 96000Hz
December182021-162029

Preamp: -8 dB

Filter 1: ON PK Fc 24.98 Hz Gain 8.32 dB Q 0.65
Filter 2: ON PK Fc 151.98 Hz Gain -5.55 dB Q 0.70
Filter 3: ON PK Fc 1938.60 Hz Gain -1.77 dB Q 2.91
Filter 4: ON PK Fc 3934.00 Hz Gain 8.77 dB Q 2.68
Filter 5: ON PK Fc 5848.63 Hz Gain -11.24 dB Q 3.22
Filter 6: ON PK Fc 6632.01 Hz Gain 9.12 dB Q 4.74
Filter 7: ON PK Fc 8382.86 Hz Gain 9.04 dB Q 2.14
Filter 8: ON PK Fc 11343.35 Hz Gain -6.65 dB Q 3.24

Koss Porta Pro APO EQ Flat@HF 96000Hz Dashboard.png
 

Attachments

Last edited:

Tks

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If you're a person who doesn't get hotspots on your ears from these (or can use Yaxi pads to solve the issue) these are just so comfy to use, it's hard going back to other headphones, especially in the summer as amir says.
 

pavuol

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EU next to warzone :.(
One have to ask philosophical questions - is it moral to sell this kind of technologically obsolete driver for nearly 4 decades just because there is market demand? (I'm speaking of that 3-5kHz shortfall)
Then I look at FR of 1200$ LCD-X and I think yeah, whatever, philosophy overloads your brain... :)

OK, the look, comfort and durability may be "iconic", but than again, those who use(d) them know that headband ripping your hair is not at all comfy/ergonomic :rolleyes:
 

2M2B

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One have to ask philosophical questions - is it moral to sell this kind of technologically obsolete driver for nearly 4 decades just because there is market demand? (I'm speaking of that 3-5kHz shortfall)
Then I look at FR of 1200$ LCD-X and I think yeah, whatever, philosophy overloads your brain... :)

OK, the look, comfort and durability may be "iconic", but than again, those who use(d) them know that headband ripping your hair is not at all comfy/ergonomic :rolleyes:
One Is a $32 on ear headphone that seen as price breaker & many use them as good sounding beaters. The other is selling a Headphone with same FR issues with a driver that can't reproduce 4KHz without distorting(It a 7.5db dip!) for $1200.

You'd think companies like Audeze would focus on getting the FR right before hyping there stuff, There IEM versions are worse. The Sundara seems to be the only Planar that doesn't have FR issues & costs $299.
 

perdido34

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Dec 13, 2021
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20
The PortaPro is very similar to the KPH30i (red). My preference goes to the PortaPro.
I have been using the KPH30i headphones (which have an inline mic) for working at home via Zoom for about two years. For voice, the sound quality is excellent, and the inline mic reproduces my voice clearly. They are extremely light, and I can wear them for hours at a time. Of course, they have zero noise insulation, which would make them unsuitable for use in a noisy office. I tried them with music, and they were basically a joke.
 

pjn

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Aperiodic

Active Member
Joined
May 2, 2019
Messages
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328
This is a review and detailed measurements of the KOSS Porta Pro on-ear headphones. It was kindly purchased and donated to the forum for review. It costs US $50.
View attachment 173165
This is an ultra light headphone that folds into a very small package:

View attachment 173166

You barely feel it on your ear and that is it. It is extremely comfortable for me.

I have fond memories of this headphone wearing on long flights to Japan when I was working for Sony in early 1990s. I remember it having a surprisingly warm sound for such a diminutive headphone.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

The cups fit my fixture's artificial ears easily although it is hard to know if they emulate how they would land on yours.

KOSS Porta Pro Measurements
Let's start with our usual frequency response measurements:
View attachment 173168

We see why I thought they had a warm sound due to excess energy between 70 and 400 Hz. Above that we have good compliance but then have two major troughs. Sub-bass is missing in action as one would predict. Subtracting the measurement from our target we get the relative response which I use to develop eq filters:

View attachment 173169

Drivers can't seem to handle bass well and have some acoustic anomaly around 4 kHz:
View attachment 173170

View attachment 173171

Impedance is variable and on the low side:

View attachment 173172

They sip power though so you should be able to drive them with most sources:

View attachment 173173

Group delay identifies messiness around 4 kHz due to reflections:
View attachment 173174

Koss Porta Pro Listening Tests and Equalization
The impression of upper bass comes across immediately with these headphones. It sounds a bit stuffy due to that, and lack of energy further down the frequency range. It is not too bad but clearly not what we want out of a high-fidelity headphone. A few filters perform miracles here:

View attachment 173175

The sound was now more open and better balanced. I was especially impressed with some amount of spatial qualities which I did not expect to come from these small headphones. Combine with the comfort they provide, this becomes a very enjoyable headphone to listen to.

Conclusions
The Porta Pro is as classic as you can get. It is good to see that it doesn't produce crazy wrong response. It does need equalization which once deployed, produces a very nice experience. It is so good that after I took the review picture, I put them back on to listen to as I am typing this! It is a nice alternative to IEMs for those hot summer days to wear.

Without EQ, the KOSS Porta Pro doesn't get a recommendation from me. But add EQ, and it becomes recommended with a smile. :)
 

Aperiodic

Active Member
Joined
May 2, 2019
Messages
213
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328
OK with EQ but how many pf the portable devices it seems aimed at will be able to provide the kind of EQ required? Some 'high end' models might, but are they going to get used with a $50, 38yo headphone design?
 
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