spritzer

The black color is often carbon and that + HV don't mix.

The B-10 was a semi difficult birth over the last few days though most of the issues were linked to the new "super simple PSU" I drew up for the amp. Nothing wrong with the basic design, I just made too many layout mistakes but it's all good now. The only issue with the amp was tracking down the source for very faint hum. I did succeed in finding it and now it's as quiet as a solid state amp. Not bad for a cramped 1U chassis, shared umbilical cable and very hungry tubes (roughly 4A for the 5687's). My only real goal with the amp was to see how hard I could push the tubes without them either imploding or the plates catching fire. The max rating for 5687's is 4.5W per triode or 7.2W for the both of them. Even at 9W for each envelope I had no issues but I backed off to 6.9W or so as these ratings really shouldn't be exceeded in a long term setup. As it stands now the B-10 is identical to the A-10 except where part changes made sense and naturally it's fitted with a much better power supply. Here is a list of the major changes: -Volume pot moved so it's in front of the first stage, not after it as in the A-10. I added 500K grid resistors on the "lower" 5687 triode instead of the pot. I don't need to fool myself that this amp is noiseless even though it really is. Dead silent even at full volume with the super sensitive SR-003. -Separate filament winding just for the 5687's which has the center tap connected to the +300V line through a 100K resistor. This is a major change since the A-10 uses two parallel connected switching supplies to run everything, tube filaments, relays etc. with the - side grounded. With one cathode in the envelope sitting way above the cathode-heater level this is downright dangerous so a floating winding referenced at +300V gives me trouble free operation for most of the output. Only at full voltage swing will I run into issues so it's not perfect but a huge improvement. -The front end it fed of a fully regulated DC supply using it's own transformer. This also drives the LED's and is a large factor in the zero hum. -Some modifications were made to the circuit so it sees a more stable load and thus behaves more like a SRPP circuit should. Ideally they should see a fixed load to behave but electrostatics are anything but that so a bit of counter balance was added. Despite all of this it is not a very good little amp. Bass is lifeless and flat, top end uneven at best and all those lovely distortion molecules... It didn't like a loud session with some metal one bit either, audibly clipping into a Lambda Signature... Still, one could do worse for the 500$ or so this cost me to build. One could have paid Ray 6.5K$ for one which is even worse...

There is a difference but the KGSS still holds its own. It's warmer in tone and more forgiving than the HV. The truly interesting comparison would be to use the stock KGSS circuit with the HV PSU and running at a higher voltage. This is how the idea for the KGSSHV initially started so I'm going to build one soon. I'm also building one with different output devices but running at +/-350V to see how I like it.

No pix I'm afraid but the glue holding the damping wool has clearly perished. The driver should be visible with the damping resting on the edge of the it. .

I clearly need to add some gold paint then....

The BATE is pretty much what we have in the schematic above. Parts of GES, parts of the ESX all mixed in together. The B-10 is my take on the RSA A-10 so improved and made safe but the basic circuitry is still the same. Looks something like this:

What's missing from the schematic would be the wattage of the EL34 cathode resistors. While all the other resistors are 1/2W these need to be larger.

These amps are designed for the ca. 120pf load presented by a Stax driver but some can drive tougher loads such as the Floats but I wouldn't venture any higher than that. The voltages we are working with are also miniscule compared to the drive voltages inside an ESL. We have been prolific for the last few weeks discussing new designs and how to rework old ones, amps and power supplies alike. Who needs sleep anyway... Given this is where it all started, the B-10 will probably see the light of day this weekend (barring any late cake orders...). The amp section has been ready for weeks but Edcor took their sweet time with the transformers. Massive distortion here I come but it will be as good as this circuit can be made.

I love fiber...

They have very exact standards those Germans...

That's looking good. Getting the mix right is half the "magic" and so is the duration of the mixing. The machines we use have two speeds so for a normal medium density bread it's 6 minutes slow and 3 minutes fast if using the German spec 550 flour. If using any of the French flours or the American variants then the times will be rather different and often unpredictable due to the high gluten. I did give mixing by hand a try over Easter and it is possible but rather time consuming. Took me about 25minutes for 1/2L of dough (1.4kg or so) with no tools except my hands. It was fun but I think I'll stick with my machines...

I was more commenting on "speaker like" presentation of the Sigma's which the Floats are also trying to achieve rather then the actual performance. If we go by that then none of the Floats even come close and only the K1000 makes an honest attempt. For me the Floats were all about impact which probably stems from using speaker drivers in the earliest versions. High voltage swing with high bias to get better dynamics. I don't know if what you heard were issues with build quality but they pretty much match my experiences. It also matches the figures as with an open baffle the bass is the first thing to go and the treble becomes more pronounced. There are some clever ways to get some of that bass back but the lack of earpads will always cause issues.

What exactly was I wrong about? Look at where the Jecklin design came from, or more importantly the drivers, and there is a whole lot of room for improvement. As for Stax not sounding natural, you are joking right? Which set and with what amp would be a much better question. If the Float sound is to your liking then it has to be a Sigma, preferably a Sigma 404.

I've been following the German thread but I'm not impressed to be honest. Sure, it may be an improvement over the PS2 but that was far from being a top end set to begin with and things have come a long way since then. They changed the connectors simply because Hirschman doesn't make them any more so it was a necessity but the cable looks like the same design. If any headphone would benefit from a lower capacitance cable then it would be those huge drivers... I don't think it is possible to run these drivers at a +600V bias in the open frame. The backwave issues are huge and the only way to overcome them is with brute force. The PS2 ran at +1200V if I remember correctly so these should be similar but more importantly the drive voltages are far higher. While Stax transformer boxes use a ratio of 1:25 for stepping up the voltage, the Jecklin boxes used 1:125. This poses a problem with Stax compatibility even though amps like the BHSE and KGSSHV should have no trouble driving them. These are all issues which we came across with the Purtscheller design ideas back in the day. He was going to offer a matching tube amp but with no Stax compatibility the design was doomed. The days of matching phones and interface devices are long gone and we are only going to see a further move towards the Stax standard in the future. To me this set looks like the old PS2 drivers in a slightly better chassis and with a better headband design though mostly borrowed from the PMB500/1000. Sure, they might sell a few sets but nothing compared to what they might sell with Stax compatibility. I do think the drivers could be redesigned to work at the lower bias and voltage swing ranges but it would take some clever baffle design and at least partial earpads (like the PMD's). This is no longer a niche market as can be seen by the hundreds of Stax SR-009's sold in just one year...

I like pie and I made some today. Also had to endure the sheer torture of comparing two cupcake recipes...

So it's sold for 100$ without a chassis or any ancillaries and it competes with 300$ dacs? I'd call that a pretty terrible deal when one thinks about how much that 300$ actually costs to produce....

1A on a 117V line is a bit optimistic as there is massive inrush current for the first fraction of a second. I use 2A slo-blo on a 230V line with no issues. Is the bias supply fully populated? There are effectively two bias supplies there so some parts are left out when you use the regulator.

Could be but they also claim they invented electrostatic headphones in 1968. Perhaps I'm just cranky from listening to the SR-009 all day...

I had a bit of interest in these until I saw the price. Also a transformer box in 2012? The Ergo Jecklin amp is cheaper to build than that box (300€ in parts with chassis would be generous) so why not use an amp? The Jecklin's always had issues with build quality and these appear to be a bit better but they still look like a DIY project gone wrong.

Is it just me or is anybody else really annoyed by the BS Koss have spewed claiming to have invented all of this? I very much doubt that they were the first ones to wire up each cup separately for stereo even though stereo was brand new at that point. So they do that in '58 and Stax release an electrostatic stereo set in 1959?

I just ran the numbers and the parts cost is about 150$ for the amp section. Most of that are the teflon sockets and all the PSU bypass caps though.

That does look an awful lot like a 6 pin din with a different collar. That would be my first place to look as you can get nice metal ones for not a whole lot of cash. It's hard to compare these with the Stax since the design is so vastly different. I'd also venture a guess that the actual diaphragm material and its tension is far more important than the pentagon stuff.

That's pretty much the same as here. We had a bit of snow mid-may (mostly in the north though) but now it should be clear sailing until mid Sept. After that anything can happen....

The assembly is more like the SR-Omega but with screws this time around. He's sent me a PM on the other site so I'll take it from here...

Can you post some pics of the plug? Most of these have some solid core which is then covered in plastic material so if you can simply peal off the cover, install new wires and then glue it all back together again then it wouldn't be too hard.