Kung

brilliant🤩

from the picture above, the driver of X1 seems to be slightly larger than that of sr-x. I remember that sr-x has a 51mm diaphragm, while X1 may have 60mm or so ？

Whoa~thats news

great job, only here in the world can see such wonderful reviews of electrostatic amp

damn, 2400x the gain, that must be loud enough to explode... there are audiophiles who judge the power of the amplifier by the position of the potentiometer knob, i guess ray samuels should have a good knowledge of this.

Don't know if it's true, the rumor from the dealer of rudistor in Shanghai said that the designer passed away a few years ago🙄, and they still have some unsold rudi amps in stock...

Still haven't heard viva stx, however, stx seems to be marketed as an amplifier that perfectly matches the x9000 in china. btw~The actual selling price is about $10000 not $32k, those products are always sold well below their list price.

From warwick official website, I think their aperio has a high voltage bias (1800Vdc) driver, which is much higher than the 1350Vdc of their lower models. it means that the output voltage of the amplifier no longer needs to be as high as the traditional electrostatic system, therefore does not require too much power and heat dissipation. In addition, for the built-in amplifier of HE1, I guess it may be the cool-mosfet version with reduced gain of the hev70 vas since Sennheiser applied for a patent(DE4329991A1) similar to the design of the HE1 in 1993. I heard HE1 once at the exhibition, and I also think that the potentiometer should be set to the position of about 2-3 o’clock to get loud enough, indicating the input sensitivity voltage can be a bit high based on the two-stage amplifier's gain setting being too low...🤷‍♂️

I predict that some people will say that true endgame headphones are all musical instruments... oh~ i see yamaha's marketing is indeed working hard in this direction though...🤷‍♂️

Yep, ASR's evaluation is just based entirely on measurements... My source told me that topping has also designed a discrete component version of electrostatic amp to drive estats directly, ap show that its specs far exceed any known electrostatic amps, and it will be on the market sometime in the future. . .🤷‍♂️

Ray samuels the old friend of stax mafia just released a new amplifier B-21, the electrostatic part claimed 1800Vpp voltage swing with 200mA continuous current output performance just shocked me. . . Reminds me of the horribly weak output performance of the A10 he designed before, this new amp is also questionable...

it is topping a90d amplifier driving step-up transformers，just get confirmed by manufacturer.

From topping's previous amplifier products, the EHA5 normal amplifier section is likely to be a composite amplifier, just like the amplifiers of jds atom and benchmark things. The common practice is to combine a precision opamp1 with a higher idle current opamp2 which has a specified closed-loop gain. opamp2 is placed inside the feedback loop of opamp1, which is the "feed forward technology" claimed by some manufacturers. In fact, it introduces a huge amount of feedback, the distortion test is usually lower than what the manufacturer's specs , but I don't know whether it can drive the transformer to output such low distortion though...never tried before 😟

Just look at the back of the Korea amp, it's almost identical to the stax t8000, even including the line4 input that never came out on the market , that's hilarious 😅 Is this just a change of box for t8000 ,or is it some kind of modification for the t8000 (e.g. load resistor changed to CCS load) with a new box?

have no idea, since no more detailed schematics were provided，the most likely one is that the plate is connected to the transformer, the center tap of the secondary winding is grounded ，then it can output signal with opposite phases to headphones

here，I found the schematic of VIVA STX without step up transformer part，disassembled by jr audio aka vertek in this forum.

yes，build everything that can make sound into a fancy box，and sell them to those audiophiles in china for over $10K，that is what these high-end brands are doing right now.

Don't worry too much about it , below 10V or even 20V is acceptable.

yes，old ones are brass. i have considered carbon fiber or PMMA as mesh holder, after comparing the metal materials, I think the metal mesh holders have better looking though...

Assembled a new pair of drivers with aluminum mesh holders，the headphone now weighs less than 360 grams which is a lot more comfortable for my neck

Just to repair my own headphones, cause I have not only hifiman cans but also several other old estats of Stax and Sennheiser. it will be more reassuring to play with these old stuffs if I can do some repairs myself.

According to your 007t schematic, if the transformer outputs 270VAC, the voltage doubler will give you about 360+VDC bias. If the transformer outputs 435VAC, you will have a standard 580VDC pro bias. because there is no voltage regulator, the turn ratio of transformer will be conservative for wider range of voltage fluctuation.

It is likely that the #80 mesh is not easy to make a stator by hand, which leads to the failure of the omega driver, and the driver housing made by resin at that time was not as strong as later 007 009 though. There are some DIY estats such as Perun and Phenomenon in Russia, they use much lower number size copper mesh as stator. I have owned a pair of perun, the stators are made of about #10 copper mesh, the mesh itself is very strong actually, and is glued to the PCB holder with structural adhesive. As for the glass stator of the HE90, the glass is indeed rigid, However, as a stator, it does not play the role in the Sennheiser advertisement at all. The only thing I can expect is that the glass is chemically stable and not easy to be corroded or oxidized, and Manufacturing microporous glass plate is extremely expensive which also leads to the insane price of the HE90... Unfortunately, Sennheiser is now not planning to stop, they use even more expensive ceramic based PCB stator on HE1.😦

Updating more DIY mesh stators. Glue the brass holder to the copper sieve with ERGO 5500 or 5900 then cut off the excess copper mesh with a nicking tool. Stators mesh size in the picture below ranges from #180 to #400，It is better to use a higher number mesh for making DIY mesh stators, the mesh with lower number size is difficult to glue...This may be the reason why stax no longer produce the original omega . Both omega and x9000 use about #80 mesh for their stator, and it is not easy to fix #80 mesh by hand, x9000 solves the problem by using thermo compression bonding...

I bought a 711 clone rig on Taobao, here is the link: https://item.taobao.com/item.htm?spm=a230r.1.14.18.b2407a72U22HcB&id=41416109881&ns=1&abbucket=3#detail Contains a clone coupler based on IEC-711 standard, a preamp, a silicone pinna and a calibration file based on B&K4128C. the clone coupler has been confirmed by the headphone factory to perform almost the same as the G.R.A.S RA0045. Unfortunately , the silicone pinna is not a standard pinna clone from G.R.A.S or B&K, resulting in an additional 5k~6khz attenuation in the frequency response diagram.