Koss Pro-4 AAT headphones

[Haselsh1]

Mini review on Koss Pro-4 AAT headphones
Shaun Haselden
Pickering
North Yorkshire

Headphones purchased around Christmas, 2011
Amazon at around £65.00 including courier

Test CD’s:

Ray of Light, Madonna
Music, Madonna
We Can’t Dance, Genesis
Merlin, Meddwyn Goodall

These headphones are a very tasteful greenish/gold colour with aluminium/silver trim but have quite cheap plasticky earpads. To confirm all rumours, they are heavy and weigh in at around 575g including the cable but once situated on your head are a treat to experience. The packaging that they arrive in is very good and well presented with the whole package being quite high quality.

To start with the sound, let’s start at the bottom as it’s always my favourite place to get stuck in. The bass has no real extension to speak of but then being headphones, I don’t wonder. There is a heavy overblown sense to the upper bass/lower midrange which sounds unbelievably congested and thick. This is the first of a series of negative comments about these headphones. I always prefer a much leaner bass with extra detail but these phones are seriously lacking in the upper bass department. On albums such as Music by Madonna, the full bass is almost welcome but the overblown sense is always there.

The midrange is stunning. The clarity, definition and purity is something to listen to. There are vocal inflections and details that I have never heard before and it is very easy to hear ‘vocoded’ voices and the words that are being spoken. I love the midrange of these headphones.

The treble is noticeable by the sheer lack of any extension. You must be aware that I am comparing these units to Dali Ikon 1 speakers with a ribbon supertweeter which I guess is rather unfair but these headphones have no real clarity or incisiveness to the treble. Taken to the extreme I guess it could be said that these Koss headphones are just plain dull.

So; do I think they are worth the money…? Yes.

Could I recommend them…? Definitely, No.

How do I justify those comments…? Simple. Sixty five quid.

[Marco]

Hi Shaun,

Thanks for the write-up. Most interesting... I wonder if the voicing is different between the PRO4 AAs, which I have:


http://img526.imageshack.us/img526/3421/pro4aa.png (http://imageshack.us/photo/my-images/526/pro4aa.png/)


And the PRO4 AATs, which you have:


http://img521.imageshack.us/img521/407/pro4aat.png (http://imageshack.us/photo/my-images/521/pro4aat.png/)


Basically because, midrange aside (and I totally agree with your comments there), from the rest of your description, they sound nothing like the same headphones I'm using! :scratch:

One physical difference which is obvious is that the earpads are not "cheap and plasticky" on the PRO4 AAs, but rather very inert, dense and heavy. I wonder if that would be having an effect on the sound?

Also, what headphone amp are you using - and, do you have the specs?

There could be an impedance mismatch, as what you're describing sounds distinctly like one. How far do you have to turn the volume control up on your headphone amp, with your PRO4 AATs, to reach what you'd describe as a 'normal' listening level?

Marco.

[bobbasrah]

That is a pity Shaun,
At least you gave them a shot and reviewed them for others.
It's a bit hazy, but think these were your first cans were they not?

I was a little surprised at the recommendation and choice at the time given the way the Superlux were being raved about, but who could be certain....
Haven't had Koss cans since my first foray into hifi (cans/amp/turntable) in the late 1970's, and your description sounds pretty familiar, which is both surprising and disappointing.

Look on the bright side.... At least you didn't spend 150 quid and end up disappointed...So you are already 85 quid ahead.....

[Haselsh1]

Marco, I use the headphone stage built into my Icon Audio Stereo 20PP amplifier as at the moment, I'm not in a position to afford a better one. Technically speaking, I know nothing about the amplifier's headphone stage.

[Haselsh1]

Marco, I have to turn the volume down considerably against using the speakers when using the headphones. I couldn't possibly listen at speaker type level through the phones.

[DSJR]

Definitely something to be said for matching, or at least, having an amp with loads of headroom when driving headphones...

I had two issues with the bryston BP25P preamp I once owned. One was the fact that the line stage took 12 hours or so to stabilise and sweeten up and the other was that the headphone outlet, with its own little amplifier I think, was gutless and distorted on loud bass notes - the first "kick drum" sound on the remastered "Poland" by Tangerine Dream was a classic for distortion I remember. Also, I bought some Sennheiser HD600's when I could get some new for around £100 and found that they sounded totally flat dynamically - all on the level. bearing in mind their good reputation as a top quality headphone, I suspect it was the headphone stage in the Bryston doing it.. Even the HD25SP's I have now sound excellent to me (all bar a slight crispness) using one of my D-60's for headphone duties (straight off the output stage with no resistor network...

[Haselsh1]

Marco, I have to turn the volume down considerably against using the speakers when using the headphones. I couldn't possibly listen at speaker type level through the phones.

Using the speakers, the volume control is set to the five too position but using the headphones, the volume control is set to the quarter too position.

[Marco]

Definitely something to be said for matching, or at least, having an amp with loads of headroom when driving headphones...


It's absolutely essential, Dave; as much as is matching a cartridge correctly to a phono stage, or your main amplifier to your speakers!

If there is an impedance mismatch between the headphones one is using and their amplifier, which I suspect may be the case in Shaun's set-up, the sound will NEVER be any good, unless the headphone amp is suitably modified, which shouldn't be a difficult job for someone who knows what they're doing.

Shaun, it's difficult to tell exactly what's happening from what you describe, but what I can say for sure is that what you're hearing is NOT intrinsically how PRO4 AAs sound, when driven by the right headphone amp, otherwise there's no way I'd be able to live with them. Either that, or there is a substantial difference in voicing between the PRO4AAs and PRO4AATs, which although possible, I doubt.

We also don't know how good the headphone output is in the Icon, but as they're a high-end specialist brand, it should be pretty decent....

It's a real shame it's worked out this way, matey. I know that someone like Nick Gorham (lurcher) could probably fix the problem for you simply by changing a few resistors in the headphone output of your amp, or perhaps you could contact Icon and get their thoughts on the matter?

All they'd need to know is the impedance of the Koss headphones you're using, which should be stated on the literature you received with them, or if not, it's on the Koss website. They will then advise if the headphones you're using are compatible or not, and if not, whether an adjustment could be made to your amp.

Failing that, sell the Koss and buy headphones that are more compatible with your amp, based on what Icon recommend. What headphones did they use to test the headphone output with, is the question I'd be asking. The ball's in your court, dude - hope it all works out for ya! :cool:

Marco.

[Marco]

Any further thoughts or developments on this, Shaun? :)

Marco.

[Haselsh1]

Marco, I've contacted Icon Audio and I'm still waiting for a response.

[Marco]

Nice one, mate. Please do let us know the outcome :)

Basically, you need to find out whether the headphone output on the amp you're using was fitted with high-quality results in mind, or simply to provide some extra functionality, and also what headphones Icon recommend would be compatible with the headphone output on their amps.

Marco.

[Haselsh1]

It would appear that according to Icon Audio, there is no mismatch between the Koss headphones and the Stereo 20 PP amplifier. It would also appear that the amplifier uses all of the valves to drive the headphone stage.

At the moment and more importantly, Icon Audio have made a modification to this amplifier to stop it getting so hot when running and so have asked for it back so that they may modify mine.

Good outcome all round really.

[Marco]

Hi Shaun,

Yes to the last bit, but it's still very puzzling how, midrange aside, your PRO4 AATs sound so bad, compared to what I'm used to hearing with my PRO4 AAs... :scratch: :confused:

Marco.

[morris_minor]

I tried a pair of 4AAs back in the 80s but took 'em back after a week; too heavy and uncomfortable. That started me on Sennheisers. Both the 595 and 650 I have benefited from a running in period. The 595s in particular were spectacularly dull out of the box: no bass, restricted treble, generally boxy sounding. However after about a month of heavy use they opened up nicely. Maybe the 4AATs need some more time?

[Haselsh1]

KOSS PRO-4AAT UPDATE

Saturday 28th January 2012

Test CD: Tina Arena, Don’t Ask


OK so I decided to give them a new try with a new technique. Here is a summary of the outcome.

Starting again at the bass end I am now easily able to detect the difference between an electric bass and a synthesized bass but as well as that, I can now even detect the difference between an electric bass plucked with a pick and played with fingers. This difference is very audible. The bass is now quite lean and laid back and the overwhelming thickness to the upper mid is no longer there; at all.

The midrange continues to stun. The level of detail is quite astonishing and clearly shows up what my little Icon Audio EL84 amplifier is capable of. The stereo imaging is vast with a near cavernous depth which places the bulk of the sound miles behind your head. The little detail of each multi-track is clearly audible and truly amazing. I am loving this midrange.

The treble is there and is good but still I am afraid not up to the standard of the supertweeter on my Dali’s. I would say that these headphones are fairly reticent in the treble and very dry sounding comparing them to a South East Australian Cabernet Sauvignon when compared to an other World Merlot. I like the dry sound as it very much appeals to me.

So, what has brought about this near miraculous change ? I promise you’ll laugh. I removed my spectacles before starting my listening session and therefore improved the seal between the headphone cushion and my head..!

Whilst I am on the subject of Tina Arena I must use this opportunity to push this CD by her. Don’t Ask was released around 1994 and clearly shows the injustice that pervades the World of popular music given that she was an Aussie soap star along the lines of ‘you know who’. This CD is a perfect example of stunning female vocals combined with delicate pop songs. A true ‘must have album’ for anyone into female vocals.

[Canetoad]

She was actually on a show called Young Talent Time (as was Danni Minogue). I don't think she was ever in a soap, other than maybe a guest appearance. She does have a wonderful voice I must admit.

I think I'll be on the lookout for a copy myself. Thanks for the reminder! :cool:

[morris_minor]

So, what has brought about this near miraculous change ? I promise you’ll laugh. I removed my spectacles before starting my listening session and therefore improved the seal between the headphone cushion and my head..!

:lol: Good one!! Those 4AAs I tried had a kind of fluid filled cushion - do yours? Another reason I didn't really like them - they were always cold when you put 'em on.:eyebrows:

[DSJR]

Marco says the originals aren't as good as the current 4AA issue and I must admit, I could never get on with the 70's Pro 4AA's, finding I got a headache after a while because of their weight crushing my head..

I use HD25SP's these days and as long as I have a treble control (don't have an equaliser) to tame the SSSparkle, they do just fine.

The best closed-back I found were the HD265's, which fitted round the ears and didn't have the boxiness that early sealed 'phones could have.

[Marco]

Hi Shaun,


So, what has brought about this near miraculous change ? I promise you’ll laugh. I removed my spectacles before starting my listening session and therefore improved the seal between the headphone cushion and my head..!


Lol - what are you like! :mental: :lol: :D

Well, that would defo explain the diametrically opposed results we were getting, as I don't wear glasses!

No shortage of treble here, though. I do agree about the rather 'dry' sound, and like you, I much prefer that type of presentation to the warm bass-heavy boom of many headphones. The Koss presentation is fundamentally more accurate. It's one of the reasons why I also like the Grado range.

And yes, the midrange of the Koss is to die for, which is why they were used in broadcasting studios for monitoring purposes, and again why I love them so much!

You'll find that they'll get better once run in fully, where the bass fills out, gaining weight and extension, and the top-end opens out more, adding some nice 'sparkle'. What I did was leave them connected for 24 hours with a CD on repeat.

Bloody bargain, aren't they? Enjoy! :cool:

Marco.

[Haselsh1]

She was actually on a show called Young Talent Time (as was Danni Minogue). I don't think she was ever in a soap, other than maybe a guest appearance. She does have a wonderful voice I must admit.

I think I'll be on the lookout for a copy myself. Thanks for the reminder! :cool:

Yeah, I think her guest appearance was in 'Neighbours' as I was married at the time and my wife was a near obsessive with the bloody program. I of course hated anything to do with it :-)

[Haselsh1]

:lol: Good one!! Those 4AAs I tried had a kind of fluid filled cushion - do yours? Another reason I didn't really like them - they were always cold when you put 'em on.:eyebrows:

As far as I am aware, the Pro-4AAT's do have the fluid filled cushions. I still think that the pads are rather 'plasticky' though.

[morris_minor]

As far as I am aware, the Pro-4AAT's do have the fluid filled cushions. I still think that the pads are rather 'plasticky' though.
My hazy recollection is that those old pads were more rubbery! I did really want to like the 4AAs, but for me comfort won the day and and nice, light open back Sennys did the trick (414s ?). Anyhow, hope you enjoy your 4AATs, glasses-free. :)

[Marco]

As far as I am aware, the Pro-4AAT's do have the fluid filled cushions.

Indeed, as do the PRO4 AAs, but they never feel cold, unless you use them in a cold room...

One area where I feel that they could be improved is in terms of the supplied connecting cable and moulded plug, which are ok but nothing special, and reflect the low price of the Koss.

I guess at this price quality had to be cut somewhere. Unfortunately, due to their particular construction, upgrading the supplied cable is not exactly straightforward.

Marco.

[BTH K10A]

Marco says the originals aren't as good as the current 4AA issue .

:nono:

[Marco]

Well, Andy I can only judge the vintage samples I listened to, which *may* not have been at their best.

The sound in comparison to the current PRO 4 AAs was rather muffled and woolly, with a distinct lack of high-frequency 'sparkle'; in effect they sounded like old headphones that were well past their sell-by date.

Have you heard the current models in order to make an accurate comparison? :)

Marco.

[BTH K10A]

Yes I've heard both Marco. What you probably heard in the older models was due to the inner foam pads breaking down and depositing onto the transducer and the foam becoming less acoustically transparent. Once serviced there is nothing in it.

[Marco]

Fair enough, matey. In that case, it's good news and shows the remarkable level of consistency Koss have achieved with the design! Any thoughts on how one would go about replacing the supplied cable for something better?

I suspect that this would elevate the performance of the Koss quite considerably. I know that RA do some nice Kimber cable, terminated in a high-quality plug: http://www.russandrews.com/product.asp?lookup=1&region=UK&currency=GBP&pf_id=5731&customer_id=PAA1233033709665INGDUPMEQGJMBKGD

But those are designed to plug into headphones with the required socket, which you can't do with the Koss... Not a cheap upgrade, I know, but given the inherent sonic capability of the PRO4 AA/ATs, I believe that their potential warrants it.

Marco.

[BTH K10A]

Having opened the vintage set up to replace the pads and foams, it doesn't look too difficult to replace the cable. The limiting factor is that you will need a similar diameter cable to fit the grommets and pass through the slot in the headband. As to whether it will make any improvement, I don't think I'm the one to ask. To me, cables are just tone controls (resistance & capacitance) and whilst I agree they can change the sound, it's more to do with matching than a brand of cable. Sometimes you can do more harm than good.

I'd suggest making your own using this

http://www.van-damme.com/15.html

Whilst I'm on the subject, this is is very good for interconnects

http://www.van-damme.com/12.html

[Marco]

Lol, dude, don't involve me in any DIY shenanigans, or I'll end up ruining the fuckers! :wowzer: :trust:

No, that would definitely be a job for someone else. Good to know, however, that it's do-able :)

Marco.

[BTH K10A]

Ok but get whoever does it to use properly engineered cable at honest retail cost rather than the latest hocus pocus that's been passed between the buttocks of aboriginal virgins to impart unheard of sonic qualities and only costs thirty times the price of your headphones

[Marco]

Indeed. Only problem with that idea is that it might not be any better than what's already on it! ;)

Marco.

[BTH K10A]

Possibly, I doubt that Koss attach a lead without undertaking any R&D on it so It may well be the optimum cable for the product.

[Marco]

Possibly true, dude. But listening to them, and having extensive experience of experimenting with specialist audio cables, my hunch would be that the supplied cable could be improved.

I guess there's only one way to find out! ;)

Marco.

[BTH K10A]

Any particular make in mind?

[Marco]

I'll need to have a mooch around. Anyway it can wait, as I've got more important projects on the go at the minute :)

Marco.