[TeamHiFiMAN]

We at HIFIMAN noticed that someone (naming no names) had decided to take apart a newly purchased Jade II Amp. Aside from the question why would someone do such a thing we noticed that there were a number of discrepancies. We would hate to say lies, as we would like to think it was simply non intentional factual inaccuracy. We are now going to elaborate on a few of the points of contention so that the community has a more accurate frame of reference.

A number of claims were made but we shall only look at 4 of them, if we were to go through everything this would become a very lengthy post.

First, there is a comment regarding the IEC and its lack of safety, however its is an integral part of the design as its required to pass certification for bodies such as the FCC to enable it to be sold to the public.

Second there was an assertion that the amp lacked grounding, along side a photo that showed the two grounding wires having been disconnected from the chassis.

In the image below we show you just where those grounding connections are made.

Third, we address the claim that the Jade II Amp is just a cheap copy of the STAX SRA-12S. Below we show the schematics of both amps and clarify the differences in their configuration and that the STAX unit uses a Single Ended MOSFET to the Jade II using a Differential OPAMP in the Pre-Amp stage. Likewise, the Power Amp out in the Jade is Transistor to MOSFET where the Stax uses MOSFET to Transistor in its output.

Note that the capacitance is not the incorrectly stated 65pf but is actually 5.49pf.

Lastly, we look at the headphone sockets. As can be seen below the Jade II uses a 1k Ohm resistor and it was claimed that a 5k would be better but functionally it makes little difference.

Further you can also see that the Stax unit has no resistor whatsoever to offer any protection.

The original poster appeared to us to have a bit of an axe to grind. Not only were the above and other inaccuracies but the post was filled with a lack of awareness. Multiple comments were directed more at China than HIFIMAN, at one point stating “Nothing from China is turned on here without being taken apart” It would seem that poster set out not to examine the inside of the Jade II Amp but to reinforce an already established opinion. Suggesting that Chinese means cheap and low-quality labour. However, the lowest paid, least educated HIFIMAN production worker costs at least US$15k per annum, a level approaching similar level workers in many western countries.

This is HIFIMAN’s home-town, near the Tianjin Olympic Stadium. Tianjin is a typical, ordinary Chinese city compared to Beijing and Shanghai where the living costs are twice that of Tianjin.

 

[Sound Eq]

We at HIFIMAN noticed that someone (naming no names) had decided to take apart a newly purchased Jade II Amp. Aside from the question why would someone do such a thing we noticed that there were a number of discrepancies. We would hate to say lies, as we would like to think it was simply non intentional factual inaccuracy. We are now going to elaborate on a few of the points of contention so that the community has a more accurate frame of reference.

A number of claims were made but we shall only look at 4 of them, if we were to go through everything this would become a very lengthy post.

First, there is a comment regarding the IEC and its lack of safety, however its is an integral part of the design as its required to pass certification for bodies such as the FCC to enable it to be sold to the public.

Second there was an assertion that the amp lacked grounding, along side a photo that showed the two grounding wires having been disconnected from the chassis.

In the image below we show you just where those grounding connections are made.

Third, we address the claim that the Jade II Amp is just a cheap copy of the STAX SRA-12S. Below we show the schematics of both amps and clarify the differences in their configuration and that the STAX unit uses a Single Ended MOSFET to the Jade II using a Differential OPAMP in the Pre-Amp stage. Likewise, the Power Amp out in the Jade is Transistor to MOSFET where the Stax uses MOSFET to Transistor in its output.

Note that the capacitance is not the incorrectly stated 65pf but is actually 5.49pf.

Lastly, we look at the headphone sockets. As can be seen below the Jade II uses a 1k Ohm resistor and it was claimed that a 5k would be better but functionally it makes little difference.

Further you can also see that the Stax unit has no resistor whatsoever to offer any protection.

The original poster appeared to us to have a bit of an axe to grind. Not only were the above and other inaccuracies but the post was filled with a lack of awareness. Multiple comments were directed more at China than HIFIMAN, at one point stating “Nothing from China is turned on here without being taken apart” It would seem that poster set out not to examine the inside of the Jade II Amp but to reinforce an already established opinion. Suggesting that Chinese means cheap and low-quality labour. However, the lowest paid, least educated HIFIMAN production worker costs at least US$15k per annum, a level approaching similar level workers in many western countries.

This is HIFIMAN’s home-town, near the Tianjin Olympic Stadium. Tianjin is a typical, ordinary Chinese city compared to Beijing and Shanghai where the living costs are twice that of Tianjin.

Thanks for sharing all this, and I am sure if there are or were issues, you would have addressed them or will address them

Anyhow your contribution to the audio community is vast, and I owned alot of your headphones among them HE1000SE and HE1000 V2 and they are the best headphones period, no other headphones in my opinion tops those 2 headphones, and I owned alot from other companies as well which are great. So I am thankful to you and your contributions

I am so eager to get a Jade 2 soon and compare it to my other stax headphones, but need more time to read more impressions first

 

[JimL11]

Um. actually @TeamHiFiMAN, you don't show the schematic of your amp, just a photo of the circuit board, compared to the schematic of the SRA-12S.

 

[jamato8]

I had the Jade II amp and Jade II headphones at a show this last weekend and they were heavily used. I have used the Jade II everyday since receiving it and zero problem.

Excellent performance with regards to function and audio and hitting way above the asking price.

 

[protoss]

Hifman challenging legendary spritzer.

Sorry, that I named the person you are trying to correct, Spritzer! Oops.

He never posted it here? He posted at his website? @TeamHiFiMAN maybe take it up at his place.

 

[reiserFS]

Sorry, but I trust in Spritzer.

 

[spw1880]

hmmm..china vs the world again..

 

[TeamHiFiMAN]

https://www.electronics-tutorials.ws/capacitor/cap_7.html

MOSFET C1=65 Pf
Transistor C2=6 Pf
Ctotal=C1*C2/(C1+C2)
Ctotal=5.49 Pf

 

[Benny-x]

Why would anyone blanketly trust anyone else?

No one would be naive enough to say or think the HiFiMAN company doesn't know anything or that they are rank amateurs. And we do mostly know that Spritzer is an extremely skilled and community oriented person.

I think it makes most sense to let them duke it out in public and then we'll all see where the cards fall.

 

[JimL11]

hmmm..china vs the world again..

Nope, just HiFiMan vs the world.

https://www.electronics-tutorials.ws/capacitor/cap_7.html

MOSFET C1=65 Pf
Transistor C2=6 Pf
Ctotal=C1*C2/(C1+C2)
Ctotal=5.49 Pf

1) MOSFETs and transistors are active devices, and not capacitors.
2) it is unclear why the equation for capacitors in series is relevant. If the transistor is driving a MOSFET, the capacitance seen by the transistor is 65 pf (and possibly even more due to the Miller effect if the MOSFET is not configured as a source follower.

 

[Dobrescu George]

Fun stuff. Is there a back answer from the people who originally took it apart?

 

[Pars]

To add to this, FCC testing IIRC is Part 15, which is for RF emission, and is not a test of electrical safety, and not even applicable to this.

[Mod Edited]

 

[Pars]

[Mod Edit]

The issue here is engineering questions, brought up by some people who know what they are doing, and know safety and proper engineering regarding electrostatic headphones and amps running 400-450V rails. Do you trust them, or do you trust a manufacturer with a track record of flavor du jour, and a defensive behavior?

 

[Pars]

I believe that all of the proper engineering concerns for the OP have been brought up already by Spritzer and possibly KG. The OP has chosen to spin and deflect (including an email to myself, even though I've only bought and returned a pair of IEMs to them...).

My reputation on these sites is beyond reproach. My only motivation in posting and using these sites is to learn. When I make a statement or opinion that is called out, I examine it, and if in error, admit my mistake and move on (as in, I was wrong).

However, it is an irritation to see users who are known shills, such as you, come in with some bs statement regarding "I had the Jade II amp and Jade II headphones at a show this last weekend and they were heavily used. I have used the Jade II everyday since receiving it and zero problem." That may be true (or not...), as I'm sure everyone who tries the product isn't shocked or whatever. The point is, the hype train that defines this very site worldwide, and that users such as you, with your "innocuous" statements such as that perpetuate.

The OP was responding to both a youtube video of someone who IIRC got a bit shocked by their product, and Spritzer, a known highly respected user and kind of manufacturer (I think his bakery takes precedence over anything he might sell audio-wise), who purchased the product on his own dime, and then disassembled said product and reported on his findings. I think he actually thought the headphones themselves weren't bad, though not at Stax SRM007 good levels. I could be wrong however.

 

[AnakChan]

I've whacked out a few posts which are off topic to this Jade II safety thread. This is irrespective of whether the content of the posts are true or not, however they are off-topic nevertheless.

Let's stick to the topic of Jade II safety - this is more crucial to audience of this thread, including myself who have a historically strong respect for the engineers who have done the work, but also am objectively open minded to see the rebuttal.