spritzer

The specs, go read the datasheet. Because Stax, under Chinese control, doesn't give a shit? The D10 and D50 have very little to do with Stax in Japan.

I'd take a transformer solution, that is properly driven, over the the Apex garbage. Just look at the specs of those modules, they are truly terrible.

Yeah, it's in many ways worse to have an external PSU but let's not get some actual engineering involved here. Go buy the Woo 3ES with a 500$ opamp electrostatic amp. That is 14K$ all in and has an external PSU... well kinda as they saw the need to have the power transformers right next to the output sockets.

The Koss unit draws 9W from the wall, max so factor in PSU losses, very high rail voltages, that you driving 4 amplifier channels and yup, there is not a lot of power there. So Woo has a new electrostatic amp out, WA7e... who wants to guess that it is a tube pre driving some Apex modules?

My friend has tagged along for the trip so I'll have to check with him but I'm sure we'll up for something on Friday.

They are odd, I'll give them that. I'm going acquire a few more (as they are all so different) and then do a review on them.

Anybody claiming that Stax bias voltage needs to increased, immediately file that with "doesn't know what the fuck they are talking about".

No... just no.

So I should cram a Koss E/90 into a gold box and charge 20k$?

Yeah and this one has more power it seems. Still pitiful but a bit more.

Yup... Apex.

The D10 uses Apex and the listing for this thing clearly states it is a D10 clone, run a bit hotter. I'll take pics tomorrow if I can find some time.

It's a D10 clone so just as bad as the D10.

Why do I have a sneaking feeling this is a direct copy of the T8000. All the controls are the same, same inputs too with the option slot as well... Yeah not good at all.

If you can find any internal pictures then that would be great. Based on the T8000 is not great as that is one crappy amplifier.

That can be debated but I fail to see where they state that the electrostatic output is opamp or even solid state based. They only talk about the tubes in the preamp section.

I was quoted some prices from a Chinese seller last year and these were around 100$ each. Genuine parts and not pulls either. No idea who that seller was but it was through one of those marketplace sites, UT source or one of them. No idea how they can make that amp so cheap but part prices are usually around half in China compared to what we see. Also plenty of stuff that gets "lost".

Thanks for confirming that, the google image translation threw up something similar but one can never trust it. Maybe that small PSU in the back is the HV +/- supply for the Apex chips? The sister amp WA33 has a similar B+ supply for the tubes from the few pics I could find.

Those phase splitters are also in the WA22 and I believe they are just transformers. I can't see any power wires going to them there either.

Since I was asked, here is the cheap China amp with the Apex opamps

This week I was browsing the net and I came across this: 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.

No, I don't dare touch them.

You need a 10K quad pot and they are quite rare. TKD does make those in the 601 series but it is tiny so it would need a PCB to make wiring easier. I'd stay away from the Alps RK27 and the RK50 is only available as 50K.

I've reviewed the pics and nothing stands out to me. Couple of things, the input BJT's are sitting in a socket which is then sitting in another socket, did you try to separate the two? That could be a factor. Now static sound from the volume control is always possible so one thing to try, swapping the input and output wires between the channels.

Please send me some high res pictures as I might be able to spot something wrong. It is also worth it to try and swap the input devices between the channels and see if the problem follows the transistors.