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.
This is an ultra light headphone that folds into a very small package:
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:
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:
Drivers can't seem to handle bass well and have some acoustic anomaly around 4 kHz:
Impedance is variable and on the low side:
They sip power though so you should be able to drive them with most sources:
Group delay identifies messiness around 4 kHz due to reflections:
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:
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.
This is an ultra light headphone that folds into a very small package:
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:
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:
Drivers can't seem to handle bass well and have some acoustic anomaly around 4 kHz:
Impedance is variable and on the low side:
They sip power though so you should be able to drive them with most sources:
Group delay identifies messiness around 4 kHz due to reflections:
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:
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.