The interesting Chuxin Electrostatic Headphones

Hi guys, I'm pretty new here. Heard that SBAF is no place for audio-snobs, so I thought a good way to say hello to everyone is to share about an interesting pair of electrostatic headphones I bought 4 months ago. Cheers


The pretext

I stumbled upon a Chinese seller called Chuxin (means true heart) on Taobao/Aliexpress about two year ago. Back then he was selling some DIY planar headphones that gained quite a bit of traction among the Chinese audiophile community. His selling point was that he knew some people in factories that did OEM jobs for some big brands, and since the factories were capable of producing some TOTL quality drivers, Chuxin ordered some batches of custom made drivers, assembled them into headphones, and sold them as experimental prototypes that required the buyers to finish the tuning jobs themselves. I bought a pair of those planars. They were fun to play with, and sounded really great. (I might write a review of those in the future when I have more time.)

A few month later, he started selling DIY electrostatic headphones. I was intrigued, like, how could someone ever get factory produced ES headphone drivers? So, with great curiosity and my previous good experience in mind, I purchased a pair of Chuxin ES headphones.

Disclaimer: I am in no way affiliated to this seller, nor did I inform him about this review prior to publishing. I purchased the Chuxin ES headphones at full price.


The package

After I placed my order, the package reached my doorstep in 2 weeks, more than half of which was spent on international transit (I'm in Singapore and the seller’s in China). For around 450 USD, I got a pair of ES cans, a custom-made high voltage headphone cable, a semi-hard headphone case, and a DIY energizer. The ES cans also had a pair non-perforated vegan leather memory foam pads attached to them.

My first thought was - oh boy, aren’t those headphones MASSIVE! They are literally the largest headphones I've ever worn. The pads measures 11cm in diameter. That's about just 1cm narrower than the HD800 earpads, but the Chuxin ES’s pads are much thicker at 3cm. The driver housing is 3D printed from nylon. As for the design… Well, we can all infer where the seller drew his inspiration from. The headband is a bent metal sheet with a faux leather suspended cushion. The clamping force feels alright to me, and the whole headset is pretty light, so despite the awkward size, they aren’t a chore to wear. The headband adjustment adopts a sliding yoke mechanism. It's smooth and tactile, it does its job looks neat, but otherwise, nothing remarkable.

Spoiler: some photos of the headphones

The cable is flat, the wires run parallel, like those attached to a pair of Stax. They were detachable. The connectors are a pair of 3-pin mini XLRs to the headphones and a 6 - pin Weipu WS20 to the energizer. The choice of connectors is quite unique, perhaps it is to prevent accidental misuse with the Stax pro-bias amplifiers.

Spoiler: more photos

The energizer was a black aluminium box. It’s sturdy, weighs about 1.8kg and smells like contact cement. It has a power switch and a female 6pin socket in the front, a pair of RCA inputs and a power inlet at the back. It operates on a 12V DC power supply, but unfortunately, the wall-wart is not included in the package.

Spoiler: Photos of the energizer

The energizer

The energizer is transformer-based, like the good old SRD-7. A single 12v DC supply powers the upconverter modules to provide the 500V bias voltage. In my opinion it’s quite a safe and simple solution.

Curious to find out how the bias voltage generator works, I took the energizer apart, and to my horror – look at the messy cable management!

Spoiler: The insides of the energizer

The upconverters are sealed black boxes. The signal input RCA are attached to a pair of tube amp output transformers. Thus, the RCA input could in fact accommodate balanced signals if the ground terminal of the RCA cable is connected to the negative output of a balanced source.

The seller recommended pairing the energizer with power amplifiers capable of pushing 10-15W into 4ohms. Some lower end ones can be found on Taobao for about 700 CNY (around 100 USD). I did not want a buy a power amp, so I hooked the energizer up to my DIY CFA2. Lo and behold, once I cranked the volume up, my CFA2 overheated to the point that the output transformers smoked! My CFA2 didn’t like the low impedance load one bit. I raged at my stupidity, so I rage-built a KGHVSS Carbon and a Grounded Grid, with a 500v bias that the ES cans required.


The sound

Here comes the beefy part of this review. I used the following set-up: PC USB (Foobar, Spotify, YouTube) >> X208 based USB interface >> single AK4497 DAC with sigma11 (pre-regulation), 3xLT3045 (3.3v for digital section, 5.0v for Vref and 5.0v for analogue) no LPF, SuSy dynalo with GRLV @+-20V as buffer/pre-amp >> Grounded Grid @+-400V with XF2 tubes >> ES headphones. All cables and wires are from my stash of trash. I chose the GG instead of the Carbon because of the genre of music I listen to – mostly jazz, vocals, sometimes rock, pop, EDM and very occasionally string ensembles and orchestras.

Spoiler: My DAC + Pre-amp, pardon the messy wiring

I am a sucker for good vocals. To me, it is the litmus test for any audiophile system. It is tough to achieve good vocals, which requires not only high amounts of details in the mids, but also a balanced tuning such that the vocals sound full-bodied, and yet coherent with the instrumentals.

The mids on the Chuxin ES is true-to-life and incredibly detailed. It is also slightly forward and performs well with a variety of genres – from jazz, to EDM, to live recordings. In Daft Punk’s album Random Access Memories, Giorgio’s monologue in Giorgio by Moroder sounds almost tangible, as if I were interviewing him face-to-face. The synth piano later in the same track sounds dreamy and forms a perfect accompaniment to the energetic bass riffs and drumbeats. The distorted vocals in Instant Crush sounds sad and fuzzy yet nicely separated from the EDM background.

In slower and more quiet songs like Perhaps Love by Jheena Lodwick, the Chuxin ES shows off its ES prowess in airy vocals, which creates a symphony with the accompanying piano, guitar, cello and cymbals, with each instrument sounding unpolluted and crystal clear. The micro and macrodynamics of the ES cans are excellent, and the bittersweet emotions of the singer could penetrate right through the music. In a dynamic and dramatic classical piece such as this, I was awed as the symphony comes crashing down wave after wave.

However, I would usually choose a busy track as a benchmark test for the headphones. Ghost of Tom Joad by Bruce Springsteen and Tom Morello is a live recording that can really push a headphone system to its limits. It’s fast, complexed, dynamic and the source is far from perfect (it’s on YouTube). The Chuxin ES nailed it. Instrument separation and imaging was on point, I could hear every accompanying instrument on stage, without any of them stealing the limelight. I was quite surprised, as this is the kind of detail, separation and imaging that I would get from a pair of headphones that costs substantially more than the Chuxin ES.

The bass is faithful and fast. With one of my favourite test tracks - Nils Lofgren’s Bass & Drum Intro, the Chuxin ES delivered a stellar performance. They rolled along well with the nuanced bass riffs and drumbeats, sounding just right with every note, be it fat and slow, or dry and fast. However, subbass performance leaves much to be desired. In tracks such as Doin’ It Right in Random Access Memories which my Chuxin planar magnetic headphones slay, the Chuxin ES’s bass runs out of steam at (and only at) 1:30, 2:36 and 2:47. Limp bass is a common critique ES headphones receive, while most ES headphone users don’t seem to mind it (not sure if I’m overgeneralising). To me, the issue is significant, but I accept it to be an ES drivers’ physical limitation.

The treble is uptight and intense. It is extended and airy when the music calls for it, but that is something hard to screw up on a pair of electrostatic headphones. Unlike the 009 or 009s which has a tasteful and nuanced treble, Chuxin ES presents its treble in a rather in-your-face and honest manner. In no way is the treble sibilant, but I would love to see a little more finesse here. Check Yes, Juliet by We The Kings and Keith Don’t Go by Nil Lofgren are two of tracks that exposed the rough edges in Chuxin ES headphone’s treble tuning.

On a side note, when paired with a Carbon, these headphones can sound aggressive and rather unforgiving. Also, the xf2 tubes on the GG gave the amp an edge in reproducing vocals, but with some more affordable Chinese EL34, the Chuxin ES didn’t sound bad at all.


The comparisons

Some caveats first: the methodology of my comparisons is flawed. I don’t own any of the high-end mainstream headphones below. I did the comparison by listening to the Chuxin ES headphones at home first, then going to my local audio shop to audition the other headphones. Take this impression with a pinch of salt.

HD800 (non-S), on Hugo 2, via USB

The HD800 and the Chuxin ES are not in the same league. Comparing a pair of dynamic cans to a pair of ES cans is like comparing apples to oranges, but I am doing it anyway.

Straight up, the ES headphone are way more detailed than the HD800. Transients and microdynamics are ES headphones’ forte.

The bass is more controlled on the Chuxin ES, while the decay is slightly faster on the Chuxin ES. Chuxin ES also has a slightly more forward mids and a relatively gentler treble.

Stax SR 007mkii on ifi Zen DAC and SRM 007tII

The 007mkii is known for its powerful mids and low end. Compared to the 007mkii, the Chuxin ES headphones has less bass slam due to the lack of a hump at the mid-bass frequencies. The Chuxin ES also sounds a bit leaner too. However, the it is still able to hold its own by sounding outright massive on tracks such as Adrenaline by Zedd. As for the level of details, I dare not comment. I remember them to be in the same ballpark, but to say one is more detailed than another would not be a fair comment because I heard the two headphones on two completely different systems.


Stax SR 009 (and s) on ifi Zen DAC and SRM 007tII

Personally, I prefer the tuning of the 009 to that of the 009s. They are equally detailed but the 009 sounds a little more down-to-earth and concrete, while the 009s sounds liquid and lighter. The Chuxin ES has a fuller sound, while the details especially in the treble region is substantially lacking compared to the 009 duo. There is slightly more bass on the Chuxin ES though the 009 goes deeper into the subbass.


The miscellaneous

The stock vegan leather pads that came with my Chuxin ES headphones had slightly stiff memory foams. I later swapped them to a pair of lambskin pads with softer foam. It tilted the sound to the brighter, but it was more comfortable.

The dust cover on the outer side of the drivers is a thin piece of perforated plastic, hot-glued onto the inner surface of the driver housing. While it does its job well, and no trace of hot glue can be seen on the exterior, this way of fixation is not ideal, and screams of DIY. Also, I doubt the plastic piece is acoustically transparent. Although it will not necessarily be detrimental to the sound, it increases the amount of reverb and resonance the headphone produces.

There is also no metal mesh dust cover on the inner side of the drivers. This could potentially lead to easier dust build-up, or a mild shock if my spikey hair somehow pierces through the earpads’ lining fabric and touches the charged diaphragm. I remedied this issue by pasting a piece of thin tuning paper on the spacer (which holds the earpads in place). The tuning paper effectively seals the dust out, while filtering off some treble glare, making the overall sound signature less uptight. For the record, the sound impressions above is made without the tuning paper.

Lastly, the headphones are extremely insensitive. The driver measures a little more The spacing between the stator and the diaphragm is visibly wider than the usual ES drivers. Coupled with the lower bias voltage, it’s no wonder that these ES headphones are insensitive. My GG is built with a dual 400V power supply. When the amp is driven into clipping, the volume only reaches a level that’s slightly uncomfortable for me. For another user who is used to listening at higher volumes, this set up might run out of headroom. Perhaps running it at dual 450V would help with this issue.

Spoiler: close-up shot of the driver

The finishing words

This pair of electrostatic headphones is quite a big bang for the buck. Its sound ticks all the boxes for me, but it also comes with some significant shortfalls – build quality, non-stax bias voltage and jack, being hard to drive, the stock energizer requiring a power amp to drive.

I would not recommend these, unless you 1) have the spare cash to spend on something almost experimental, 2) have the means to drive these headphones, either using a power amp or a dedicated electrostatic amp with customised bias voltage, or adapt the plug to fit a Stax pro-bias socket and use with commercial energizers with adjustable bias.

Spoiler: Side note on bias voltage

There are Chinese users reporting success with using adapters to hook these headphones onto Stax pro-bias amps. Whether this 80V increase in bias voltage would cause any harm to the drivers, I wouldn’t know. But those users seem to enjoy the sound they get so far. There are some products such as the ifi pro iESL that has supports 500v bias. I suppose they will work well too.

Edited for typo errors, inserted images

 

@dingding123 Your pics are not showing, buddy. Try Imgur.

 

^ not seeing pictures either.

good info - fwiw, I initially suspected a possible shill review, but by the end it seemed like you had a legitimately good time with several aspects of your two Chuxin products and wanted to share.

Curious though - you mention SR007 having powerful mids and low end. What energizer is this with? Asking to help us better triangulate your reference points, preferences, etc. Also fwiw, I've always felt that the SR009 and SR007 are very technically adept, but the "body" was never quite there for me (along with tuning and other factors, etc etc).

 

If the spacing between the diaphragm and stator is wider than usual, there should be no issue in using a higher bias. Maybe the intention was to prevent the membrane from sticking to the stator, which is generally harmless anyway.

 

I'm interested in the planar. You got the link?

 

photos are up. @Jerry thanks for the imgur tip! I'll PM you regarding the planars.

Correction: the 007 I heard is the 007mkii.
I listened to the 009 and 007mkii on SRM007tii on ifi Zen DAC. The 007mkii has one of the most "powerful" sounds among the Staxes. If the 009s were a fast, nimble ninja who is capable of delivering precise attacks, then the 007s would be a tanky samurai who strikes his swords with gusto and resolve. Granted, they sound lacking in body and weight when you compare them to dynamic or planar magnetic headphones like the LCD series, but among ES headphones, the 007 is definitely a heavy hitter.

Thanks for the tip! Will surely try increasing the bias.

 

Tried to search for chuxin or his offerings in the aliexpress, but wasn't successful. At least not with the keyword "chuxin" in alphabetical letters. Could you provide the link to the seller? I am wondering how the developer describes his products.

 

@Vtory , provided by @dingding123

https://item.taobao.com/item.htm?spm=a1z10.1-c.w4004-21111047615.8.5b287824ybDA1c&id=582791407480

 

@Tachikoma Thanks for the tip again. I adjusted the bias to 580V. The ES headphones are definitely much more sensitive now. Interestingly they don't clip at the volume level where they used to anymore.
On a side note, I briefly tried the energizers with my susy dynalo. The dynalo didn't overheat like the CFA2. Perhaps it's got something to do with the parallel output transistors.