KOSS PRO 4AA Review (Headphone)

[musicforcities]

The Pro4AA bass response does not change going from a Schiit Magni 3+ to a ~150 ohm output vintage stereo amp I have.

Well that’s a lot of output impedance. No wonder the receiver messed up the porta pro feq response. The Magni 3+ has so much power and do low an output output impedance matching is not an issue. Usually lower output imp is better anyway. But way back when pre Walkman days way back, headphones were designed with higher output impedance in mind often.

 

[sam_adams]

So…much…brushed metal! Me like very nice.

Those looks like they may be supraural? Resting on top of your ears? I had a grado sr60 and those things killed my ears if I wore them over 20 min in spite of the foam pads. Urgh.

The coating on the foam is a hard vinyl and the foam is probably made from the ground up rubber from some old WWII Panzer rubber roadwheels. Ten minutes of wearing them and you're in agony. The fact that they sounded terrible never entered my mind as I couldn't wait to take them off.

 

[amirm]

Classic bass seal issues with Amir's rig.

There is nothing "classic" about it. Research shows that the flat plate of my measurement gear gets better results as far as fit/bass response than the ones that are shaped like a human head. If I can't get proper seal with it, you better bet you won't either. Indeed, my equalization efforts showed the deficiency in measurements translated into listening test results.

 

[sergeauckland]

There is nothing "classic" about it. Research shows that the flat plate of my measurement gear gets better results as far as fit/bass response than the ones that are shaped like a human head. If I can't get proper seal with it, you better bet you won't either. Indeed, my equalization efforts showed the deficiency in measurements translated into listening test results.

I've always used 'sealed' headphones as my use has predominantly been in studios, where spillage from open headphones is unwanted. ALL headphones that I've used have issues with sealing properly, and the bass improves if I increase the side pressure with my hands, but clearly, that won't be of much use if one needs one's hands to operate the equipment. My PRO4AAs and my K270s both have the same issue, as did the Beyer DT100s and others, that of 'variable' bass depending on the seal, whether I had to wear my glasses, how much hair I had over my ears...much more in the 1970s!

My conclusion is that headphones are a very poor substitute for loudspeakers, necessary at times, but not to be relied on to present an accurate frequency balance, or indeed stereo positioning.

S

 

[Not Daijoubu]

If I can't get proper seal with it, you better bet you won't either.

While this statement corrobates with the experience of multiple people who have used the Pro4AA before, it does not agree with the impressions of multitudes of others, so your statement comes out rather presumptuous and overgeneralized.

I can't really speak for the others, but I think I'm pretty sure I can hear the difference between bass that rolls off within -5dB of the midrange and one that plummets to the abyss as inaccurate as ears are.

That said, I'm not questioning the validity of your measurements or own listening tests. It's just that it would be erroneous to generalize over to a population after a single sample, however "good" that sample may be.

 

[uwotm8]

All Koss headphones I've heard sounded bad, especially top-hyped Porta Pro

 

[infinitesymphony]

These were the first headphones I ever heard, checking out records from the library and putting them onto my father's Sony HP-328 turntable/8-track/tuner/integrated amp combo.

In hindsight these sounded like listening to music through a seashell. Very sensitive to positioning, but it did make music seem like it was being beamed in from another planet.

 

[Joachim Herbert]

A friend had one of theses back in the 70ies. They featured fluid filled ear cushions, but that was about it. There is nothing to their sound that might distort.

 

[Ron Texas]

IMO it needs way too much EQ. Thank you @amirm

 

[SMJ]

Hi all

First, as this is my first post a thanks to @amirm for running this wonderful resource.

Anyway, couldn't resist this tread...

Rather unusually, I have been employed as a pilot and as a sound supervisor in the past so this topic seems relevant in a strange sort of way.

You have to agree that the Koss are very much aviation inspired in their design. You can see the similarity even to this day with the current David Clark headphones. But that was the fashion in the 60s & 70s, they would at least match your RayBan or Randolph shades & leather flying jacket!

That mid range peak is useful too if you only wanted to listen to Air Traffic Control. The gel ear-pads are there to stop sound getting in to your ears - it gets very noisy when the jet engine is only 4 feet away from your backside. The downside was the mess the pads made when they burst!

Spin forward several years, I find myself in a TV studio rigging the mics for a rock band session. If you've ever watched videos from the 70s & 80s, you occasionally see a horizontal pattern of interference modulating with the sound. It's caused by the sound pressure from band compressing the glass of the camera tube and giving all the internal components a bit of a shake - yes, it was that loud before the 'white coats' arrived with sound level meters. Not surprisingly, this made it difficult to hear the production gallery talkback. As the often supplied Beyer DT100s weren't that good at suppressing the sound, it wasn't long before several pairs of aviation style cans found their way into the studio for use by the sound and camera crews, the Koss included. I was still coming across discarded pairs in the back of store cupboards only a few years ago.

SMJ

Sennheiser HD414 (2kΩ) and HD40 (1980s vintage)
Modern stuff - Sennheiser Momentum 2, Beyer T51p & Sony MDR7506

 

[beagleman]

While this statement corrobates with the experience of multiple people who have used the Pro4AA before, it does not agree with the impressions of multitudes of others, so your statement comes out rather presumptuous and overgeneralized.

I can't really speak for the others, but I think I'm pretty sure I can hear the difference between bass that rolls off within -5dB of the midrange and one that plummets to the abyss as inaccurate as ears are.

That said, I'm not questioning the validity of your measurements or own listening tests. It's just that it would be erroneous to generalize over to a population after a single sample, however "good" that sample may be.

I owned these years ago, and they seemed to NOT lack bass at all.

 

[phoenixsong]

I owned these years ago, and they seemed to NOT lack bass at all.

Humans are creatures of trends and habits. My own tastes have transitioned many times since I joined the hobby, as well as my beliefs (used to use the iFi iUSB3.0 and such- it does alter sound, but not in the way I would like). Not saying they are bad though, it's just my preferences and the way things are. If you now present to me a headphone or IEM that is teetering on the edge of my tuning preferences but has prominent charms of its own, chances are I would listen to it; and after 2 months my "reference sound" would have adapted. This is why I tend to value rapid-switching side by side comparisons (if A-B blind testing is not an option) that are made after a sufficiently long period of not listening to anything

 

[phoenixsong]

I owned these years ago, and they seemed to NOT lack bass at all.

Also, I think some others have posted measurements made with the original pads. It is definitely more bassy, but still with roll-off. Maybe relatively bassy for headphones of that time, when models like the Sony Qualia were revered as perfection

 

[Joe Smith]

These things are why the Sennheiser HD 414's sold so well beginning in about 1973. They were a quantum leap in good sound from the standard US made closed back headphones then available. Even with 600 ohms impedance, as most receiver or integrated amps put out enough power to power them quite nicely.

 

[Ken1951]

These things are why the Sennheiser HD 414's sold so well beginning in about 1973. They were a quantum leap in good sound from the standard US made closed back headphones then available. Even with 600 ohms impedance, as most receiver or integrated amps put out enough power to power them quite nicely.

Indeed. I loved my old Pro4As but at the audio company I worked for once the HD414 and HD424 came out we had trouble keeping them in stock. And they were much more gentle on the ears, comfort-wise, as well.

 

[Danddd]

I had a pair of these in the early 70s. I remember listening to Led Zeppelin II from my Titan Stereo 8 track player. Those Koss were very uncomfortable headphones even as a 15 year old....

 

[beagleman]

I remember the 4aa from the mid 70's and they didn't seem to lack bass at all back then. Incredibly heavy and uncomfortable though, but th emain alternatives we had were the DT100's which I found incredibly coloured sounding and the shrill HD414 Sennheisers (I still have a pair and the 2k impedance makes them useless unless fed straight from an amplifier).

The pair I used for years, was from the mid 70s also.

Old memories or not, they never lacked bass like this one Amir just tested. In fact, the bass was quite strong at times.
Perhaps NOT really the same headphone drivers.

Needing 25db of bass boost?? I remember them as being a headphone (one of a few I had) you did NOT need to boost the bass on...?

 

[beagleman]

I had a pair of these in the early 70s. I remember listening to Led Zeppelin II from my Titan Stereo 8 track player. Those Koss were very uncomfortable headphones even as a 15 year old....

They could play quite loud, fairly clear and could make your you sweat and head hurt ....

 

[DSJR]

Just noticed and can't edit now - it was DT150's I disliked as the pros have used for fifty or more years