spritzer

They are electrets but Audiotec also made full blown electrostatics as I've seen the schematic for the energizer. Bias is -300VDC...

Happy Birthday Jeff!!

The aim of the thread is to consolidate all the info that is out there of old and frankly strange electrostatic headphones we come across. I really should have started one of these back in 2005 when I started my collecting but hindsight and all that... So I'll start off with one so rare that there is pretty much no info out there for this set. Here is what it looked like when I got it: These were made by Audiotec in France and aside from some brochures back in the say we know nothing about them. There isn't even a model number on them or a left-right identifier. They are quite big, roughtly the same size as the SR-Omega and the back of the fork is pretty much a clone of the SR-1,2 and 3 setup Stax used. Here are the earcups opened and these do have the honor of having a truly unique earcup design. No screws as they use nails which are friction fitted. Very secure assembly but an utter pain in the ass to disassemble... Not sure what is up with that baffle. It made of the same material as really old PCB's but those traces don't go anywhere. Driver lifter out of its cradle and doesn't this look familiar. Turns out that it's the same or very similar driver to the ones used in the Stax electret models. Never seen one with the mineral wool damping pad being a part of the driver housing though. Same pic but showing a bit more of the green wool pad used on the back of the driver. This keeps the driver in place against the baffle similar to the Magnavox sets but it's a far from ideal setup. There is also very little to keep the back wave from colliding with the front and that foam around the driver is decomposing quickly. Showing the connections inside the cups. The joints simply have fiberglass insulation pushed over them but not secured in any way. Yet another thing that needs to be fixed... Here is the original 6 pin DIN connector. Oxidized all to hell so I simply removed it. Now the important bit, how do they sound. Well I don't have the original adapters so I had to make due with what I have at hand... I knew that the stock transformers used with the Audiotec stuff had very high stepup ratio (1:65) so it was no surprise that the highly modified SRM-007tII didn't manage to drive these even at full volume. I do have a few KGSSHV's here and they did a stellar job with a very balance sound signature. The bass is a bit odd given the housing and all the colorations it adds but not bad at all. Finally here is how they look now but I'll do some further mods to them. They really need a new cable and some baffle insulation... Last but certainly not least, great thanks to Luc for giving me this set to play with.

In a sense yes but also not. It's an odd one...

Yup, more strident than hot though.

Yup and 250$ if I'm not mistaken.

Mk1 drivers won't fit in mk2 frames, at least not properly... They look identical but the Mk2 units are just slightly smaller. It is rather odd that the 007Mk2 gets no respect when the 009's voicing is so similar.

One can never have too many transformers... Nope, it's a company that only does bulk orders so anything below 800$ FOB carries a hefty penalty.

Makes a note to design something even more inefficient...

Every KGSS needs a good home. I was just doing some inventory and I have just about enough parts for two more KGSS and then I'm out. Now I have the strange urge to build a Blue Hawaii though...

The Sigma Nova I have suffered the same damage and the driver was half split open. Not recommended unless you are up for some delicate surgery...

Pain to assemble which is why I went with IKEA...

Some further news, the first use of the new power board: Sorry for fucking up the focus... Works like a charm and fits perfectly in the spot it was designed for. No more flying wire connections for voltage selection and primary connection. Part of this: My personal amp... well until somebody pleads with me long enough and I sell it. That transformer is from my bulk order and it is seriously awesome. Can't tell if the amp is on with an ear right next to it...

That's basically it. Electrostatics only appear to be simple in theory but then again, most don't understand the theory. Take something like the Stax Lambda, almost all of them share the same housing, basic driver building blocks (stators and diaphragm assembly), cable and earpads yet they can sound very different from one another. Hell some use the same diaphragm material yet sound nothing like one another. I blame the turtles....

It's next on my list but I've run out of parts. It will be complete Mouser amp too with Fairchild output devices so part sourcing is made far easier. Also a 400V design is cheaper to build as we can go back to single caps in the PSU. Those Edcor transformers are excellent plus it's easy enough to remove the endbells and mount them sideways.

I like to do things in bulk. Another thing of note, a comparison of the old KGSSHV boards and the new HVk boards in the same chassis...

Well that too.

Simple fix for that, MOAR gain.

Injection molding?

Is there a better way to spend a Saturday than with a pile of KGSSHV boards? I did confirm my suspicion that BUL216 doesn't work without serious mods as an output device. It's a shame as it can just about take +/-450V. There is another pile of boards that was supposed to be tested today but I've run out of parts at the moment. That pile will include a documented and tested way to run it at +/-400V but at higher current with the onboard sinks which should be interesting.

Genuine Stax sockets which means the front panel had to be modified a bit.

Well if he's inside the EU then he's paid 20% VAT (well should have though there are ways...) which would account for some of the difference. Still it's good to buy from Justin as the stuff doesn't loose any value. I'll go off and pet my custom BHSE...

What about Lexan? Polycarbonate is silly strong...

It feels a bit James Bond villainy but this is very cool indeed. I had a lengthy discussion about this and superconducting windmills working under storm conditions recently with some friends who work with this stuff. Crazy amounts of power possible if the stuff can actually be harnessed. They did say our current geo-thermal plants were impossible to build and maintain but they keep working perfectly.

Needs MOAR IRON!!!!!