Here's what you will be reading about in my review:
1) CX6 Physical Characteristics
2) How it sounded out of the box
3) How it sounded during the 600 odd hrs burn-in period
4) How it sounds now, setting into its final sound signature post 600 odd hours of burn-in period
5) How it compared against post burn-in CX95 and post burn-in CX500
6) How to use the CX6 for optimal fit & comfort
What the CX6 has is a well designed physical structure to sit in your ear & not protrude out - this way you can wear a bike helmet or a cap covering your ears without affecting the sound much, since the CX6 will level with your ear and not be pushed in more than necessary.
The plastic used is very light.....so light that people who associate weight with build quality will never find the heart to shell out more than 2 dollars if they'd close their eyes & hold the CX6 in their hands - BUT, that does not mean that the CX6 is by any means - BRITTLE !!.....It is quite sturdy & rugged although not the best in ruggedness by any means.
Finish quality is very precise, edges & corners have that laser-cut finish quality that you'd come to expect of a $240 IEM.
That said.....lets look at the CX6's WORST physical problem in the picture below:
Doesn't look like a CX6 ?????
You are wrong - this *is* the CX6 after a year of use - what you thought was a high class Brushed Aluminium panel is actually just a brushed aluminium finish on plastic that starts coming off after you touch/brush against the panel about 50 times.
Sennheiser didn't & still doesn't bother to mention this and what I thought would be a Great idea to provide an Aluminium panel to dissipate heat & maintain thermal balance turned out to be a cheap paint job.....Shame on Sennheiser !!
Not that I would not buy the CX6 if I knew this, but I would have made an *INFORMED* decision & taken proper steps to ensure the longevity of the paint job - Now my $240 IEM looks like cheap trash that people wouldn't own if you paid them to !!!
I will never forgive Sennheiser for this besides the fact that most of their service executives or dealers do not even know of this & refuse to help me on it (and they can't too) !!
This CX6 is being used with a Creative Zen without bass boost & custom equalizer set to 12-7-4-7-12, reviewing volume '15'.
Right out of the box, the CX6 sounded nothing less than a throwaway price nameless chinese earphone with too much muddy bass - it was PURE NONSENSE. Then again, even CX500 & CX95 sounded pure nonsensical when they were right out of the box.
The bass was loud & really the only frequency you could mostly hear & it was very muddy - you could hear loads of bass, but could feel none, if you know what am saying - not the airy balanced moisturized high quality bass that you feel like air moving against your ears & don't hear much but still bangs your brains - Just the opposite.
Mids were existence, but lacked the density and body & fine detail that makes you hear the phlegm in the singer's throat - low on detail, weak definition, no smoothness, lacking in fine character, no depth.........NO GOOD !
Treble was so minimal, that it was a wonder I could even manage to hear some cymbals - forget picturizing the instrument spacing or the metallic texture of treble ( I tend to picturize treble notes as metallic rods, whose numbers, temperature, structural integrity, fine mirror finish depends on the quality of the treble)
Soundstage was just a fist sized blob on the centre of my skull protruding towards my face from the inside - imaging was precise though.
Really, reviewing an IEM/OEM right out of the box and *Concluding the performance of the Monitors* is ........CRIMINAL !!
After 50 hrs or so with a 10 minute interval every 5 continuous hrs of running - tamed the bass a bit, but did nothing else.
100 hrs - bass remains how it was after 50 hrs but mids are smoother, toned & treble begins to open up - soundstage remains unchanged & Instrument separation almost nil.
100 - 400 hrs : Really, this was the working period of CX6 - way too many changes & way too many times to document. Sometimes the CX6 sounded balanced, for a few hours bassy, few hours like a SONY (too much mids). Really cannot remember the changes, but it fascinated me, it was really an educational period with me trying to picturize how the diaphragm characteristics were changing over time. Neither did CX500 or CX95 or Custom 3's give this quality of changes during their Burn-in periods.
400-500hrs : By this time almost 8 months had passed since 5th Feb 2009, the day I bought the CX6. Finally the sound seemed like it would settle any time. But I'll not explain anything cos I don't want to take anything away from the experience after 600hrs. Let's just say, the CX6 was finally at the end of teenage & on the verge of adulthood !!!!
600 odd hours: My CX6 is a MAN !!!
Remember the description of the CX6's sound right out of the box? - there is no relation to that sound at all - ABSOLUTELY NONE.
The CX6 is now an entirely different IEM - as different as an apple is from an orange.
The CX6 is now a RAMBO IEM - Powerful sound, tons & tons of power......gut-wrenching, brain cell murdering yet clean bass.
Schiller's Gluck Und Erfurllung 320kbps mp3 track on my Zen sounded like it never ever did - I could feel (not just hear) the low thumping bass beat hit my brain flesh, not hit a point in my brain, but the whole brain. Like as if my skull was empty & was filled with TIGHT, High Pressure bass !!!
The bass had body, depth, precise moisturing and it was moving my ear drum, not hitting it - if you get the meaning.
Mids.......now now now.....how shall I describe - now my *empty* skull filled with bass is also filled tightly with all the mid frequency range instruments & vocals. I could hear parts of the music I never *monitored* before.
I felt like the diaphragm opened up the track to more detail with a magnifying glass to monitor the details - and as for mp3's.....detail also includes compression errors and also the damped muddled quality of CD quality sound as opposed to the supreme quality of records.
The sonic precision was amazing - I could actually analyze the sound of the guitar string being strummed at the moment when the musician makes contact with the string & you hear the cracking sound just before the resonant frequency of the string generates the guitar tune.
Sound of the stick hitting the drum diaphragm just before the drum made its characteristic sound.............and the phlegm in the singer's throat ------ALL OBVIOUS !!!
Treble .........FINALLY !!!.....at last I could finally enjoy the high quality treble. Now, you must understand, the CX6 treble is not about irritating/piercing quantity but fine quality.
All those metallic rods, spikes, ice daggers I associate with treble notes finally reached ample representation in my mind. I could literally touch the treble notes & feel their metallic texture with my fingers & tongue - I'd appreciate more high freq amplitude but the CX6 was not fatiguing at all.
Its so different from CX500's shrieking treble, but not to the level of CX95's treble amplitude - but definitely of higher quality precision & fidelity.
The frequency response of CX95 was & still is the flattest among any dynamic driver IEM in existence - but the sound pressure, density & soundstage body of CX6 is like comparing a pressurized cylinder to a low pressure gas cylinder - the cylinder being compared to the listener's skull !!!
There is no corner in my head that is not filled with wide CX6 sound - to the extent that the soundstage is wider & higher than my head itself, although it varies from song to song & Vacuum tube recording to Transistor amp recording.
The CX6 sounds warm but not to the extent of sounding boring.....its very precise in that department, which I am confident will be bettered in the IE7 & the stellar IE8 (once burned-in)
Unfortunately, I do not have access to a high quality professional record player other than an old Sony - so I am really limited to monitoring low quality CD sound & even lower quality mp3s.
Yet, am keeping things in perspective here - so don't be carried away too much by my description. If you use records with sound recorded using vacuum tube amps - then its an entirely another plane to refer the CX6 with.
In that level - I don't think anything less than Quality Electrostats would do justice to tube amps & records.
Is the CX6 worth the extra money on the supremely balanced CX95???
Its all about perspective :
1) If you want out and out balanced sound across the frequency range, don't buy the CX6 over CX95
2) If you want way more powerful sound with tons of far more sonic pressure & power - the CX6 shoots the CX95 in the head with a shotgun.
3) If you want to feel the bass in your head trying to leak out of your head & make you feel as though people around you might hear it & you can't afford IE7 or IE8 - then CX6 is the one for you as it has better isolation than the open acoustic IE6.
4) CX500 & Bose IEM are like tin cans compared to Industrial machine like CX6 - its all about POWER, POWER & more greedy, shameless disgustingly naked P.O.W.E.R !!!....CX6 gives you the taste of the IE8 at half the price - it really is like BMW 335i giving you an idea of what the M3 GTR would be like !!!
5) Is the CX6 worth the money for an Audiophile? - Maybe, maybe not. Armature driver supporters may not like the bassy sound or the warmth of the CX6, but to me dynamics are the way to go - after the CX6, am never going to even bother about the dry, clinical armature sound - after this, armatures are zombie IEM's to me - detailed maybe, but emotionally dead....probably because of better harmonics range of dynamics & fuller sound compared to cross over loss in multi-driver IEM's !!!
6) One funny thing is that CX6 (IE6 too) makes IE7 sound like a stupid decision - it is IE7 that is not worth the money sitting between CX6/IE6 & IE8 - IE7 does not give you the price advantage of the CX6/IE6 or the Satanic sound of the IE8. So the more sensible upgrade to the 6 series seems like the IE8. So that's one thing I learned after one year & having fully experienced CX6 & previewed IE7 & IE8 sound (not fully burned in though)
I use the smallest tip on the CX6 - it feels non-existent after 2 minutes. Hallmark of Sennheiser Engineering, really !!
Where the CX95 lugs at your ears, the over-the-ear professional design of CX6 keeps the IEM firm in the ear.........I think every IEM must be over the ear type - the wire doesn't lug at the IEM & pull it out or weaken the air seal.
So when the IEM's are pushed in to the right depth, maintaining a balanced air pressure in both ears - you don't want anything to disturb the precise air pressure balance or game's over !!!
The Denon AH-C751 may have slightly more bass & treble than CX6 as reviewed by cnet (I wonder if this comparison was with a fully burned in CX6 which I highly doubt so) - but the denon WILL pain your ears in an hour, but the CX6 won't do it until maybe 2 days of continuous use .......its that comfortable !!
It take 5 - 6 tracks for me to fully concentrate on sound & forget my body & if the heavy Denon will start irritating my ear at this time - no point in buying it to listen to a few intense minutes as compared to hours of intense music experience with the Super-comfortable CX6.
I lubricate my ear canal opening with a drop of water spread on both forefingers & applied to the ear canals - to provide the instant air seal with the CX6 - you can use saliva for better seal as saliva has slightly adhesive characteristics as opposed to mere water......its all a matter of what crazy stuff you are willing to do to get the best out of your IEM !!!!
Now this notch as you can see, probably has two purposes - but whether Sennheiser intended both purposes.....I do not know :
1) The notch helps maintain balanced pressure - as your body heats up the air in an IEM ear-canal seal, the air pressure inside the ear increases causing more resistance to diaphragm movement, hence affecting sound quality & performance
2) As you push in an IEM - the pressure increases in the ear as the air gets compressed between the ear-drum & the IEM diaphragm - the notch helps maintain the designed air-pressure (the pressure level CX6 designers intended the diaphragm of the CX6 to work best. Hence avoiding diaphragm damage if you put in your IEM or pull it out suddenly causing drastic pressure changes that might damage the IEM diaphragm permanently.
3) The notch helps provide a pathway to push dirt using the cleaning tool, out of the mesh section as you can see in the first picture in this topic sub-section.
Whichever of these reasons Sennheiser intended for the notch/canal - both are applicable as far as my experience with the CX6 goes.
I may have forgotten a few details - I'll try address them as & when they are pointed out.