Received my
ES4 a few days ago. (from GB, 17$)
Out of the box, with the stock starline medium tips, sound is muddy with soft big bass and no detail.
With the small starline, it's only better
But with the spiral large opening tips (Aliexpress 1.88$) it is realy good ! ES4 is very tip sensible
https://fr.aliexpress.com/item/Hot-...962.html?spm=a2g0s.9042311.0.0.40696c37ud3i08
After sometimes but before any burn in:
The bass are very good, indeed (but I still slightly preffer those of the ZSR)
Medium are not recessed at all (recessed on the ZST & ZSR) and very very natural sounding: accoustic pianos and voices are very impressing (The ES3 sounded artificial)
Trebles are good and detailed, not sibillant at all (ES3 was sibillant all the time) , you have to listen, the global feeling is that it is less detailed than the ZS6, but on the ZS6 it's exagerated.
I remember when I got a Stax electrostatic earphone, At first listening, I thought it was sounding very bad compared to a dynamic Koss.
I had to learn during 6 month to listen differently, then only I realised the Stax was much better. Commercial produced by marketing tend to be a bit show off, but after a time are fatiguing
The "filter" (one sided board) shows 4 smd components:
C1 (capacitor unmarked value) possibly around 3uF ?
R1 (value 0, = dummy)
R2 (value 0, = dummy)
R3 (value 6R80 =6,8 ohms)
it seems that this "filter" is generic and could be used with other earphones where R1 R2 could be used)
I believe the capacitor is to cut off the bass off the BA driver
and the resistor to lower the level off treble, but normaly there are two resistors, one in parallel, + one in serie, to keep the impedance value
No correction applied to the DD
Resistors do not distort the sound, but capacitors do. The microsize of the smd component
don't give much choice: it's ceramic or tantalum (better)
I personaly use only film capacitors (mkp) for speaker filters, but they are not micro smd.
It would be interesting to test if this cap has a bad influence on the quality of the trebles
# with shunt of the capacitor
# with a replacement film cap as Wima MKP or MKS (placed outside the ES4)