spritzer

I would never ship anything secured like this. There is an awful lot of energy in those caps so if something goes wrong it will go bad in no time. Why not just use the small caps which are the ones people are actually supposed to use here? Also has anybody measured the noise from the amp? With the compromised ground on the circuit boards and the input/output wiring it could be pretty bad.

You are running the bias off the regulated B+ rail so regulating it again doesn't really make sense. Low drift resistors and you are golden.

A lot of this amp is an example of how not to wire any electrostatic amp. There is so much fail in there but lets start off on the big stuff, how the caps are mounted... Never do something like that!!! Uninsulated spades on all of the AC input wiring when they clearly should be insulated. Input wiring runs right under the transformer when it should be kept as far away from it as is possible. Last but not least, the output wiring. Twisting it like that is bad idea as it adds to the output capacitance of the amp.

Now we would just use the SiT's if we want more voltage. Less hassle and better performance. If we were to stay with tubes then there are few options but most are rare tetrode/pentode small transmitting tubes.

Never put a cap after the ballast resistor. That will damage the headphones over the long term. Stax used to do it back in the 70's but have since learned their lesson. That cap would work before the ballast but I'd still leave it out in favor of a cap before the divider. The 10M90 is worthwhile to do to fully regulate the bias.

DHT's are pretty much incompatible with this and why would you want to use them, just look at the graph for a triode connected EL34. All the later power tubes were just moar power and don't like high voltage at all.

You can put a tiny cap after the divider I like the safety the divider brings so as little storage after it as is possible.

There is a lot more to this than simply what the tubes voltage rating is. A lot more...

I'd just tap into the B+ with a voltage divider and a ballast resistor.

Wow....

Yeah there is nothing to bleed the bias supply but it doesn't have a whole lot of energy in it.

All BC parts I've ever seen are marked BC*** while something like this points to it being 2SC32725.

Humidity and the PCB quality could be an issue here along with dust. The solder resist some manufacturers use is a bad joke and will not insulate much.

1mm for those voltage levels is overkill to the n-th degree so it should never have shorted. We use 25mill from the pads to the ground plane which is 0.635mm so 1mm is plenty. The flux however will short out the boards and it has to be cleaned off!!!

Hehe true but using cheap meters at these levels is no joke. No protection circuits, the insulation in the leads is an unknown quantity and the actual measured value can be way off. Doesn't mean you have to go nuts, I have some 100$ B&K Precision meters here that are just excellent.

Not really about something better, those things are unsafe and can kill you. There is probably no protection inside them so you could kill your self or even blow up the amp.

Yeah, close to zero volts DC doesn't make any sense unless the diodes are toast. If they were shorted to ground then it would all explode.

You need some better meters though. :)

Nope, nothing like that. There will be no details of it just yet but it is all custom. I was never happy with the group buy stuff for various reasons so I'd never use it.

I asked about the price of solo headsets but they just don't know yet. They would also be useless without the amp. They will not share anything about this, as of yet. My guess is that they never will as why would they? Doesn't make any sense to have us picking over the schematics and showing what is undoubtedly a piss poor amp design. That just leaves buying a set and taking it apart which is a 50k$ gamble. If I did something like that than it would be to design a superior amplifier and not share the findings with everyone. You can thank scum like Cavalli for that...

Two DMM's are a good idea just to check if one is functioning ok. They don't have to be expensive but stay away from the no name stuff. I like B&K a lot for the cheap stuff but there is also Brymen, Extech etc. A used Fluke 189 and you are set for life though. The Morgan Jones books are excellent and have a lot of practical stuff in them. All of my books are in storage due to the impending move but there was one which was quite good, Practical Electronics for designers or something like that.

But you are crazy!!

Yup, must use paste everywhere. I even put it between the panels which attach to the heatsink for better thermal behavior.

Just leave them alone.