spritzer

The blue caps are probably the WIMA FKP's so that could be 470pf/2000V. Still, those are kinda important... I'm also wondering what's lurking underneath the boards. Could be the missing resistors from the board as thick films bonded to the sinks.

There is a newer version too with a full size PSU so they can be stacked. So pretty much a WES which isn't terrible...

I'd rather have gone with "in Russia, amp listens to you"...

So, who wants to see the Russian Blue Hawaii? http://fluxlab-acoustics.com/Products/11 Looks kinda nice but they are using the old parts so sourcing them must be an utter pain.

The L-2 fully balanced would be very complex and defeat the point of the circuit IMO. I did tell Doug to just put an XLR output and be done with it though. That felt paper stuff they use on the surface of the tweeter panels. That felt is utter overkill but these were also nearfield monitors.

I agree here, these mods went too far which is why removed them all after a while. Subtle surface treatment is all you need sane as you get around tweeters.

It's the first of the two designs they published in 1968 for DIY use. The second, which is at the bottom of the page (you can just make out the tube types), is the SRX. This design fits with just one rectifier and the low voltage rating of the tubes used. They could have used a voltage doubler after the rectifier but it makes little sense since the EL84's really don't like 300V or more. There are also just 8 tube sections in those 6 tubes and only two ways to go about it. Either you use this setup with a two stage phase splitter into the output tubes or a diffamp on the input which provides enough gain and uses one tube for each channel. The small amp I built with the Ikea bowl over the transformer is essentially just that, this circuit with a differential amp input to make it fully balanced but run at +300/+600V.

It is a good idea to never rely on the insulation actually insulating. As somebody on HF found out, the shell of the caps is connected to the negative terminal which is fine in a simple B+ setup (where the negative is always grounded) but here it is prolematic. If the cap is sitting on the PCB then just the thin shrink wrap is all that sits between 650VDC and ground. Even 1mm of clearance is enough for 1kV or more at high humidity so that makes sense.

The new ones? Shouldn't be necessary with the increased tolerances. Edit: Also won't help with this since it's trace to ground plane, not something that's on top of the board.

Well we should never have to rely on the solder resist for insulation. It's very thin on the boards Tran has made though

Anybody want to bet that this is the basis of the M-20 amp?

This is a PCB issue but whether it's the design or the fabhouse that gets the blame is the bigger question. Those traces are seeing upwards of 650VDC but the insulation should be adequate on the boards and more than double what is needed. There is not a whole lot of room for error though which is why we more than doubled the clearance on the mini boards. I usually have my own boards made and I haven't had this problem even with my mini boards which are the same spec as the older boards. As for grounding, simply connecting the XLR to the chassis assumes that the chassis is a perfect conductor when most are far from that. The real culprit is humidity and temperature extremes when shipping something. These have metal stators so freeze them in the cargo hold and then bring them back to room temp or even far more in high humidity will cause problems. The resistive coating traps the static generated and voila... imbalance. Now ship something like this on land at it is much less of an issue.

Doesn't mean anything past the usual upgrades Stax made to their long running designs. The SRA-10/12S went through at least 4 different power supply layouts though they are all pretty much the same. Two preamp revisions too but it was mostly change of parts. Which brings me to your issue, just sub that part with some modern Jfet. Stax moved to the 2SK30A in the SRA-12S so that might work (too lazy to compare the data sheets), K117, K170 and all the Fairchild Jfets. Just find one that's close and the right Idss and try it. Just watch out for the pinout.

I missed your PM by about 10 min or I would have taken you up on it. Not sure when that other set arrives... I'll be sure to test that headband to destruction too. ECC83's and EL84's... are they high? Pretty similar to this then: http://en.dubieltubeamps.pl/102/eurydice-stereophonic-tube-amp-dedicated-to-electrostatic-high-class-headphones/ Which I just sent Kevin a link about laughing about it. At least the Kingsound isn't 3K+$ like the Polish one. Both will have very limited voltage swing in common... severely limited.

This happens during shipping so it's not a Stax QC issue. Just an annoying quirk of electrostatics.

It's the Cali Audio show this weekend or is it the next one... not sure. Anyway, aside from being such a douche there is the issue of heaps of people having paid in full not getting anything until the "distributor" orders more units. Shouldn't people have been told so up front? Don't tell my dad that as he really wants a new Range Rover. At over 300K$ I told him I'd have him declared legally senile for such an act.

Just get another Jag... you know you want to...

Turns out Drew wants to send Kevin a used unit from the Cali show. What a fucktard and he's even going to charge full price.

They will always work on a lower bias but going up can be tricky and cause a bunch of problems. It should be noted that Drew is pretty clueless about this stuff.

Looking at the pics, that socket looks a lot like the SATO socket Stax use.

They will be thoroughly tested and taken apart.

First pics of the King Sound production models: http://forum.doctorhead.ru/index.php?app=gallery&album=113 http://forum.doctorhead.ru/index.php?app=gallery&album=114

Ahh yes, better leave them in then. Been spending too much time lately walking people though the simplified PSU...

Happy Birthday ohh glorious leader!!

We could also make the options a bit clearer with a picture of the boards and what should be populated for +/-500V, +/-450V, global feedback only, no servo etc.