spritzer

Those noise issues have nothing to do with external sources but rather a flawed circuit design.

Happy Birthday my friend and it was awesome meeting you last month.

No but a shielded transformer is a must have and keeping all the wiring away from the transformer. Here the input wires run directly next to the transformer. It must be said though that a ground plane is a better solution than running ground traces all over the boards. Both in terms of shielding and the low potential of the ground but something had to be done with people shorting out the amps. If we pull back the ground too much then it comes patchy as the part count goes up relative to the board size.

That is the cleaned up original of the PSU and you can see how all the other boards were based on this one. This is a smaller version naturally as my boards are always much smaller. The ground plane was indeed removed because people had been having issues with parts being too close and it shorting. The assembly needs to be perfect or you are in trouble. For my boards there is a heavy ground plane on both sides of the board hence the swarm of via's all over the place.

This is a place for people to learn and calling this "a perfectly executed build" needs to be called out. Trust me on this, what others had to say about this build was far harsher. I for one couldn't care less if you are selling Carbons but if you are building our designs then do so properly. That has always been the deal and the simple fact here is that this build is severely compromised. For the record, here is the original SiC PSU from February or so and what is the cap value? 400V version for the BHSE but the same circuit. Yeah some people wanted bigger and for a 3U chassis it isn't a problem but if the caps don't fit in the bloody box, use smaller caps. This PSU was also intended for the Circlotron which uses much more current, hence larger caps.

I would never use more than 330uf in this circuit which is what it was designed to use. Two 680uf in parallel gives 340uf.

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. :)