Kameleon portable headphone amplifier

The X2 is more forgiving because it is a bit 'V shaped' in a certain area.
Because of this recordings that have an agresssive nature (which resides between 2 and 7kHz) the X2 makes this a bit flattering.
Below the plot of the X1, which won't differ that much from the X2 I reckon.

As you can see the possible shrillness in a recording between 1kHz and 5kHz is substantially lower and thus less audible while the bass, mids and treble are still at normal level.

The HD600 runs flat similar like the HD650 (slightly less midbass hump)
Below the HD650 as reference.


Any shrillness in the recording is 'accurately' reproduced and thus more audible in the HD600 than in the X2.
This means that the shrillness in the HD600 isn't a negative feature of the HD600 and the fact that it sounds more pleasant on the X2 isn't a sign the X2 is better.
It's not the fault of the DAC nor the used IC's... Shrillness (in this case) is a frequency response related issue only, and originates in the recording studio in MOST cases.

The TPA6120 is a good amplifier section with decent properties.

The frequency response of Ember is equally flat compared to the TPA6102, the Ember differs in power, flexibility, and ADDED (pleasant) harmonics.
The Ember thus is tonally different but adds a bit of 'extra' in the bass area.
That will be the same on both headphones.

I haven't heard HD600 and X2 side by side and at home so can't recommend one over the other.
It also depends on taste etc.
The X2 can be driven directly from portables, the HD600 not so well... those kinds of things.
Taste and music genre could also be a deciding factor.

BOTH headphones are good ones, the HD600 is technically more correct, the X2 may be more pleasant on popular (studio) recordings.

I kept my HD650 and returned my X1... I really wanted to like the X1 cause it looks and feels great.




some relevant info from another threat (the words O2 have been replaced with TPA6120):

The Ember and TPA6120 (as well as all other amps out there) all have equally flat frequency responses.
What Ian says is correct... you often read amp 'this or that' has boosted bass or suppressed mids or whatever.
It is complete bollocks they are all equally flat (if well designed)

They can still sound different for 2 reasons.
1: output resistance interacting with headphone impedance creating a frequency dependent voltage divider (forget about the damping factor nonsense)
2: Added harmonics.

See it like this...
A pure sinewave of 70Hz has an amplitude of lets say 0dB and lets assume that is 1V
A pure sine wave has no harmonics.
Now we have a tube amp that puts out the same 70Hz tone also at 1V
It ADDS harmonics so the first harmonic = 140Hz and is at -40dB which is a factor 100 smaller in amplitude so 0.01V
The total output voltage is thus 1.01V and consists of 70Hz + a small signal of 140Hz
When you will be looking at the FR plot of the non distorting amp (lets call this the O2) than it will show 0dB at 70Hz (1V = 0dB).
When you will be looking at the FR plot of the distorting amp (lets call this the Ember) than it will show 0dB at 70Hz (1.01V = +0.08dB) BUT a plot is created referenced to 1kHz and 0dB.

at 1kHz the amps do the same and also at the other frequencies so from 20Hz to 20kHz both amps will show the same.
with the same input signal (a pure sinewave) the TPA6120 will always give 0dB and the Ember always +0.08dB so both are equally 'flat'
When we make a plot of the Ember and want 1kHz as 0dB than the input signal is lowered by -0.08dB so at 1kHz it shows 0dB and also at all the other frequencies.

BUT... here is the kicker.
The TPA6120 will only let you hear the 70Hz and the Ember will let you hear the 70Hz + a MUCH softer 140Hz but you'll hear it non the less.
Just not as 2 separate tones but as one tone with a more natural 'warmth' to it.
When the 70Hz and 140Hz were not related and would be 'free running' you would hear 2 tones.

So both amps are equally flat but because the added harmonic signal is VERY small in amplitude it won't SHOW on the plot (well as a marginal raise in amplitude) but your ears will hear it and measurement equipment that shows THD will show the signal and an FFT plot will also show it.

Now when you have 'corrected' the anomalies of the FR of the headphone it will be tonally correct but the Ember will still add the harmonics (tube goodness).

Of course it should be noted that when a 70Hz (or another frequency) pure tone is played through a headphone that headphone itself will also add quite a few harmonics. The amount of harmonics is frequency dependent as well so will differ from headphone to headpone.

The HD600 has very low distortion b.t.w. and once FR corrected it will thus sound 'better' than some others.
The 'added tube goodness' will be faithfully reproduced by the headphone and is thus audible.

Also, just to say that the HD 650 - even without the filter - sounds sublime when powered by the Ember. Absolutely gorgeous.

If I were in your position I'd be looking to get the 650. Other than initial cost I see no good reason to settle for the 600, particularly if you intend to use a filter further down the line.

Hi Ian

You are using the same filter of HD650 when listening to HD600 or you got a proper filter for it?
Also your HD600 and HD650 are the "newer" version or the older ones?

Wednesday the courier took back my X2. I kept Sennheiser HD600.

However I purchased an aluminum SC version of Ember and some tubes from Jeremy.. growl! =D

Hi Frans

I'm about to build Kameleon No.3 and want to dedicate it to the HE6s. If you could have a look at a filter for it as above that would be great, when you have time.

Meantime, is there any likelihood of the actual main board needing different components to suit it? If not I'll press on.

Syd