spritzer

The SZ markings are indeed useless.

That seems likely...

Not sure. Basically, he claimed that he got a shock from the headphones and he was numb in that ear after a while.

2SA1968 now will pretty much mean fake. I doubt many real ones are still in circulation as we have been dealing with fakes for about a decade now.

As it turns out...some people are not happy with the Jade.... I'm not sure how this could have happened. Last person on the planet here to defend Hifiman as they produce nothing but garbage...but the headphones are just made from plastic and PCB material. On the inside of the cups, there is a built in mesh into the pads, then we have a grill made from FR4 and doesn't look to have any traces on it. Now it is black so often tricky to see but yeah... doesn't make any sense to put a track on that part. Next up with a have a gap, then the dust cover, then the strengthening rib for the inner stator and finally something electrically conductive, the stator. Now all of this does flex so you could theoretically push your way to the stator but you are still nowhere near the bias. Now the amp is not fundamentally unsafe like the Woo Audio garbage but also not what I'd call safe. The earthing is suspect at best and the amp lacks the right value safety resistors but at least there are some in there. The audio output is AC coupled to the stators so no high voltage DC could be present there. The 1k output resistors would also seriously limit the current if something were to happen...

They fuck it up here even if I stand over them so I completely get that...

That must be it as this isn't terrible at all. I'd pick the ESP950 over it or any Lambda but it's nowhere near the old Jade level of shit.

Looks good!!

That is the best way. You could do something fancy and regulate the bias but I wouldn't bother.

Those are actually silistors and I'd remove them at this point. They don't age well and at 30+ years old... jut them off. The damping is on all sides of the housing and needs to be very dense or it won't work at all.

Yup, sounds like it. Could me a marginal part like a cap or something like that. Well either that or the PSU is failing. It's not the 100V unit, right?

There is nothing about it in the datasheet but in my experience it is a bit longer but not by much.

We've gone over this numerous times but storing any amount of energy after the ballast resistor can make arcing much worse than it would be otherwise. Normally arcing shouldn't be destructive unless something extreme happens. The schematic you posted looks like the ESL63 design which is very old at this point and Stax were even placing caps after the ballast back in '82.

There is no difference to the amp section, it just how they did the tube delay on the early units.

Yup and swap out the tubes. Is the shield on the transformer connected to ground? Ideally it should be earthed...

Crap...I always get that wrong!!

I feel the ginatricot bag is part of minimizing nasty conflicts...

Yup and earth the chassis. I would never leave anything like this floating.

Sounds like it comes from the amp. Should happen with it off though as the caps in there are tiny and can't hold much of a charge.

First thing to try, is there any sound coming from the headphones right after you disconnect them from the amp? It's not a good idea to keep the headphones in plastic bags so I would stop doing that as it can produce charge issues. Second, what power supply are you using for the amp? Hum from the amp is the most likely scenario or coming in from the source.

Well step one for hum issues, keep the input wiring well away from the transformer and its winding's.

Good point...

I just put together the amp and Fang should really fire everybody in the "Hifiman Boston design team" for coming up with this shit. So there is really no good way of assembling this as you can't just put on the front or the back first and connect the internal wires. Nope, they have to hang off at the same time while trying to connect the fiddly connectors. Fucking hell... It will be fun for them to service this shit...

Pretty much... Seriously though, for 500$ this would be a solid set of headphones but for 1500$? Not really... Some points I never touched on, the system comes in two large boxes and the headphones just come in that shipping box. Not even placed in a bag or anything (no desiccant bag either) the issues of shipping will be further amplified.

Yeah, it all looks like that. Well except the cable, if that lasts a year I'd be amazed.