This was introduced at High End 2025 in Munich and here is a blurb about it

Quote

The cleverly named BLISS e-stat amplifier is not your regular tube-based amplifier. Everything was cranked up to eleven! It’s huge, it’s big, it’s heavy, and it’s over the top using quad Stradi 300B power triodes, quad EL34 power pentodes, and quad Reflektor 6E5P tetrodes for some power overwhelming action. We have two headphone sockets, one for normal (low-voltage) e-stats and the other for PRO (high-voltage) e-stats. The wheel on top also lets you adjust the voltage bias for the headphones attached. The normal bias goes from 120V to 360V, while the PRO bias starts at 240V and finishes at 720V, letting you use most, if not all electrostatic headphones available right now on the market.

Now, I admit I wasn’t thrilled by the entry-level DAC hooked up to the Bliss, and using an Astell&Kern DAP as a digital transport seemed more about convenience than conquering sound quality. Yet, even with this setup, both the STAX X9000 and HiFiMan Shangri-La Sr delivered a fabulously fun-tastic performance! Oftentimes, I get so lost in the tech specs that I forget to savor the experience, but this time, I paused, closed my eyes, and a few captivating minutes later, someone had to rouse me from my trance-like state.

Priced at €20K a pop, the BLISS might not be everyone’s cup of tea, but if you’re in pursuit of the pinnacle, I can’t imagine a better auditory experience. Hats off to the Feliks brothers for blending art, passion, and cutting-edge engineering into these timeless, handcrafted amplifiers! Our Best Of Show award goes to the magnificent BLISS, and I eagerly anticipate another encounter, hopefully at the Audio Video Show 2025

There are no internal pictures at all but it sure looks like they stole some of our Megatron here.  Yeah, if that is the case, that is not okey.  At first I didn't know what driver tubes were used and since those look a bit like 6N6pi's... I thought "well that is stupid but it might kinda work if used with some transformers".  No... it is far worse.  Single tetrodes, likely triode strapped, so are they trying to out compete the Woo WES for the worst all tube electrostatic amp design...or maybe the Triode H1?  Time will tell but there simply aren't enough tubes here if the EL34's are used as current sources. 

Now we get to the proper stupid shit... why have that bias adjustment?  It's the same garbage as ifi have been doing and just as retarded.  It simply shows a complete lack of understanding at the principles at play here and is a good way to burn up some headphone drivers.  Are they switching in different ballast resistors and limiting the output voltage swing to match the bias?  No, probably not so let's pump up that X9000 to 720V and burn it up.  Yup... what a brilliant idea. 

http://bbs.erji.net/forum.php?mod=viewthread&tid=2239622

Now it is all in Chinese but these were the first pictures of the insides of the Woo Audio 3ES.  This was an amp I never really paid any attention to, I'm so fedup with Woo and their sub-par crap, but finding internal pics does warrant a look.  First off the pics aren't great but at least there are some schematics there and we need to try to verify they are correct.  We have no further info than this as I can't find any more internal pics, so this is what know at this point.   First the PSU:

Now, nothing new here, same old crap Woo have been building for years but why place the output sockets right next to the power transformers like that?  I mean the whole idea behind a two box solution is to place the noisy power transformer away from the amplifier and thus the output, not run the signal back into the PSU and have the output sockets right next to the, rather large, radiation field of the EI power transformers.  Makes no sense but things are about to take a turn to the worse: 

Now... here is where things start to look a bit off and I'm going to see if anybody can spot it without venturing further.  Now neither Kevin nor I can read Chinese so the markings on these two schematics that were included meant nothing to us:

We focused on the tube schematic and wondered how this could work, I mean it is a simple grounded cathode 6SN7 input with a 300B cathode follower output.  We are not dealing with a lot of gain here so at first the schematic had to be wrong, no way to drive electrostatics from this.  Then Kevin figured it out, this is just a preamp, the latter schematic is the output for the headphones and what is that... it's a fucking Apex PA97 opamp!!!

https://eu.mouser.com/datasheet/2/156/pa97u-1853045.pdf

Go on, double check the pinout against the datasheet and look at the recommended values.  Now look at the internal picture again and follow the wires, input selector is on the left and the preamp/headphone selector is on the right with the red wires.  What's there next to the back panel with 4 identical modules and a shit ton of hotglue?  The electrostatic module... which is made up for 4 of these which cost around 100$ each in bulk.  This is a 14k$ amp! 

Now we don't know what is on the heatsinks next to the tubes, has to be a TO220 size part but no way to see what it is.  The rest of the schematics make sense though.  B+ goes directly onto the 300B plates and there is a grid resistor next to the "G" pin with the cap from the 6SN7's right next to it.  Two large resistors next to each filament pin too.  Then we have the large, brown, resistors going off the B+ to feed the 6SN7's and two identical plate resistors for it too.  . 

Now what is the problem... well I can't see anywhere on the Woo site which says this is a hybrid amp, they talk about the 6SN7's, 300B's and the rectifier but nothing about a basic opamp outputs for the electrostatic outputs.  Let's just quote them: "The new 3ES achieves the most ambitious dream in the audio world".  Yeah... not so sure about that... 

Funny enough, clones of the Stax D10 are surfacing in China now and I have one.  Guess what that one uses?  Apex opamps....  and I bought one for 250$ shipped to me and it fits in the palm of my hand. 

Below are the rest of the pics from that Erji post for posterity.

scheme ->

psu ->

>Max output voltage: 280Vrms

It doesn't seem like a very powerful thing.

What do you think?

First post here. I am curious about building an electrostat HPA as I only have an SRD7 Mk2. I am interested in some of Kevin Gilmore's designs like the KGSSHV variants and the T2, but the legend about the KGSSHV seems to ring true that it is hard to build and hard to learn about. Is there somewhere I can read about these different designs in white paper format like Nelson Pass does with the First Watt amps? I can't even find schematics or a BOM. It's truly a nightmare, and I don't want to endlessly bother spritzer with questions. Frankly, I am not totally sure of the "authorship" of each of these amps which makes it harder to research.

I was considering first building a Nectar Agave since it could probably be finished between semesters, and it has a clear BOM, PCB files and a cost estimate- where as the KGSSHV line is known to be good quality but near impossible to read about.

I don't expect to understand everything, just hoping to understand more what makes each design unique and uniquely capable at driving an electrostat to decide what to build.

Thanks in advance for any pointers of where to read about them.

I just sold my SRM-717 to a Stax 009 user. As it landed at his place, he also had a loan Woo Audio GES to try out. I remember back in 2009-2011 there was a lot of posts from users about that amp, but now it has tailed right off. How does the GES stack up today against Stat amps at that price range (Stax SRM-007t or 727). Thinking the 009 is more efficient, maybe it will be a good match?

Is the GES an adaption of a KG design? I spotted this on the Woo web page:

• Schematic re-engineering is based on Dr. Gilmore's design.

Spritzer repaired it back in April of 2023. The HV- line wasn't working due to a failed resistor and a capacitor was starting to fail. At the time the left channel was much quieter and had a buzzing noise before I stopped getting sound at all. It had no issues until September or August of last year.

Any thoughts or help are appreciated. I attached some pictures of the amp. Nothing looks obviously amiss to me.

what do you think? does it look good or bad? found this on the net today

My Question, 
1- Which Amp do you recommend to connect to my Marantz Cinema 30 and my Sennheiser HD 800s Headphones?
2- Is the DAC in the Marantz sufficient or I will need a separate DAC?

I don't want to pay over the odds, yet I want one that has the power to handle the Marantz and Sennheiser and blend well together. 

Kind regards
 
 

Got my entry ticket into the Stax world in the beginning of 2018 with a Lambda Signature SR-407 earspeakers / SRM-T1S energizer combo. Got them from a Japanese seller and therefore I'm having to use a 100V step-down transformer for Japanese electronics here in Brazil (power outlets at home are 127V, 60 Hz). Only recently got the nerve to open the energizer to remove some dust and check the components (a bit scared of touching those big-ass 100 uF caps, but an anti-static brush and a lens cleaning blower sort of did the job).

As far as I could see, all components seem original:

• The tubes are Gold Aero 6CG7's, Stax Signature selection. I understand that Gold Aero is not really a tube brand, but they rather select NOS tubes from various different brands. The only info I could get from the tube rear is that they are 6CG7's (not the equivalent 6FQ7) made in USA. (Edit) Comparing the remaining original lettering's shape in the tube rear with pictures from Ebay tube listings pointed to the tubes having in fact been made by Sylvania, most likely in the 1950's. For example, this 1956 6CG7 tube made by Sylvania for Zenith looks exactly the same (apart from the Zenith red print replaced in my case with the Gold Aero print, of course), particularly on the inside:
  
  https://www.ebay.ca/itm/1956-Sylvania-Zenith-6CG7-Test-NOS-Grey-Plates-Silver-Shield-Serious-Tubes-L398/174307174026
  
  The tubes have grey plates with a silver center shield and a copper grid.
• The four, big 100 uF caps at the bottom right are Hitachi (CE W 85oC, 400V), but they baffle me somehow - the exact same cap brand / model looks very different in other people's SRM-T1S's pictures (usually black with aluminum / black top, unlike the bronze "unibody" ones in mine), so I wonder whether there is something special about them or if the different looks are only due to the period they were made.
• I've noticed that the Alps potentiometer is sometimes mounted in the opposite orientation elsewhere (with the PCB facing up instead of down as in mine).

My listening so far showed nothing wrong with the combo (apart from a grounding issue - see 5. below) and I've really enjoyed the experience so far - my only previous contact with electrostatics was listening to Martin Logan ESL's, but the technology has always fascinated me. However, I worry about the long-term maintenance of the energizer, considering its age and my distance from the manufacturer, so I eventually need to learn to fix it myself. I may also consider modding the energizer in the future to improve it if it stops working properly. This leads me to the following questions:

1. How do I identify tube / cap failure, apart from the glowing of the tubes? I have no experience at all in that (in due time: all 4 red LED's inside the energizer are glowing, including the one beneath the Alps potentiometer);
2. Should I need to replace the tubes in the future, which brands are most recommended for my combo? I've seen several people here in the forum recommending prioritizing Japanese brands for a better match - how do they compare to my Gold Aero (Sylvania)s?
3. Should I need to replace the electrolytic caps in the future, which brands are most recommended for my combo?
4. Do I need to worry about the long-term wearing of other components (resistors, diodes, input MOSFETs)?
5. Most likely due to the use of the step-down transformer and the fact that my apartment's power outlets are not grounded (sorry, old building), the energizer suffers from occasional humming when no signal is being fed (I use the balanced XLR inputs from a Fiio X7II DAP, which happens to have balanced output). Any ideas? Would modding the power supply help?

Does any know the correct way to adjust tvr-1 and tvr-2 in SRM-727? Thanks.

I also found 727 is a good paring with hifiman jade 2.

Somebody who studied Head Case is now building and selling a 'stat energizer.  Kind of interesting because it's only $160.  Worth it?

The SRD-7 was bought just as an experiment, I did not really expect much from it. Besides I had read that the SRM-T1S should be better. However, from day one I have felt that the SRD7 mk2, coupled to a Pioneer M-22 power amp and a Pioneer C-21 preamp sounds much fuller/dynamic/better lower end compared to the SRM-T1S. The SRM-T1S seems flat or lifeless in comparison. 

I was sure there was something wrong with it, it is an old amp after all. I tried biasing to no effect. I thought that perhaps the capacitors need replacing and have replaced them. No change. I thought that perhaps the tubes it came with were bad and I bought a set of 2 new balanced 6CG7EH electro-harmonix tubes, did the biasing and balance procedures and still no real change. 

What am I missing? What else should I be checking?

The SRM-T1S has been stored for the past 4 months while I patiently waited for my account to get approved on the forum, gave it another go today and impressions remained the same.

I am renewing 25-years 717's and I observe strange things:

I noticed a lot of wet places - as if sweaty - I suspect it has something to do with high voltage, have you noticed such symptoms in your old Stax? It's probably old flux - but these are places where it shouldn't be - output sockets, bottom of heat sinks (between PCBs).
The second issue - how does the output protection system work - it draws voltages only from two outputs +L and +P? Because that's what I saw on PCB. What are the soldering points marked 81,82, 83 and Test: R,L,V for?
I know that Kevi n had a diagram of this system somewhere, but it is no longer available .

I have tried every possibility to optimize the circuit, but finally STAX has chosen the worst one. I'm pretty sure that STAX has gone with SMDs, it all fine, most parts in working will not generate lots heat, also SMDs significantly reduces the distributed inductance caused by PCB board through holes.  

...... there some analyze and questions:

1, 4 large sized 7W 47kΩ resistors work as plate loads for 6SN7s, but higher value must be better, for example, two series 33K as 006T, or at least 62K 7W will far better than 47K, because 47K means too much current flow through 6SN7s, in my simulation is 9.5-10ma (grid at -9V), it's fine for 12AU7 or 12BH7, but 6SN7GT....hmmmm.

2, There are limited choice for input differential Jfets, I like using Toshiba 2SK2145 in my design, but the common sink package doesn't work here, also there are SMDs, so I guess they would better swapped to HN1C01 BJTs from Toshiba, the same thing may happened with Q6 and Q7, these components might be replaced with TTA010. Don't ask why not BC846BS, they are Japs......, local brands first as always.

3, In simulation I placed two 1815s on Q8 and Q9, but if you want to save cost and place, 2SC4944 will be better, by the way, you can also save 1 100Ω resistor due to the common emitter design.

4, The negative rail load R19 perhaps still wafer resistor in real life, which power dissipation will reach 500mW, hope they put a large size here, don't let the T2 tragedy happen again.

Extra: I didn't see any improve on original 006T or T1, there are nothing wrong with 6FQ7, the 6SN7 only consume more filament current and......in some old Chinese 12BH7s, they only swap the glass package to 9 pins, inside stuff was 6SN7 or 6N6, so in my opinion , most modern 6SN7=12BH7=6FQ7......so use 6SN7 in 700T is pointless.

Here I can compare directly against the Carbon CC and the as yet unrealesed new KGSSHV, budget edition.  Think of this one as the 727 if Stax had any sense.  Anyway, back to the T8000.  The packaging is classic Stax and no complaints there.  I do have some complaints about the casework though, the front panel looks awesome but who decided what to do with the rest of it?  Seriously that sparckly silver paint is just horrible.  Reminds me of some super cheap Chinese amps.  Yeah... not great. 

I had a quick peek inside to change the voltage to 240V and the procedure in the other thread is correct.  This is the same old Stax color setup with a small change (one connector is reversed) to try and trick people.  Some notes about the interior:

-The person who designed this needs to find something else to do as not a single fuck was given as to how this thing is put together.  Boards on top of boards with no reason to be there.  I love the volume control where you have three PCB's (one blank) sitting on top of the pot.  WHY!!!???  All of this could have been done on the back panel...  Also wires everywhere.  Bloody Stax living in the 70's... 

-The volume control (which they try to hide) is a plain old Alps RK27.  It's almost impossible to see but I moved the "shield" a bit and there was the classic Alps sticker.  For 6K$ I'd expect more...

-The PSU is certainly unregulated and the same as in the 727/007t.  Same 220uf/400V Elna caps. 

-Looks like the tubes are running at DC 6.3V.  4700uf/10V filter caps but I'll measure it later. 

-The amp is certainly just a 727 with the feedback in place and tube input stage.  Ohhh and for the tube rollers, not a chance to roll this amp so better just like the stock EH tubes.  Either that or somebody builds a special tester for this amp and sells tubes for it. 

Now for some impressions.  I'm a bit pressed for time now so I just grabbed the first headphones that I saw.  These are my own DIY units and I've been using them a lot lately as I've been tuning them.  The drivers are old SR-X Mk3 units so similar sound signature, the best highs you can find with glorious midrange and extended but super tight bass.  I'll go into the living room and grab some of the others over the weekend. 

Now what can I say about the amp...well I expected more.  The top end is the worst part, it's rather uneven and unrefined.  Grating even and slightly shouty in nature.  Seems to be the Stax house sound these days but it also makes me dread trying the amp with 009's and L700's.  I'm listening as I type this and I cringe from time to time, the upper midrange and treble is so bad.  The phones are sure as shit not to blame... 

Now the midrange is ok minus the glare but it also lacks the expansive nature that the really powerful amps give it.  It feels closed in... 

The bass...well it is nothing to write about really.  Nowhere near T2/Carbon levels of power but this really isn't the best set to try for bass performance.  I'll dig out the modded 007Mk2's to test that when I have time.  Here it is all a bit flat and lifeless. 

Conclusion time I guess, at least for now.  There are things I like about this amp, the front panel is pretty and it comes with properly wired XLR sockets but there is a lot I don't like.  I fucking hate the blue power led...Stax should be green or orange.  On top of everything above I also think this thing is horribly overpriced as it is just a fixed 727 which isn't a particularly great amp to begin with.  To charge 6k$ for this...is just not cool. 

More listening to come...

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