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Well it really does depend on what you test. I've just run some of my stock of C2240's and they are all high. The one I've just put on the Peak is 453. Sa am I surprised at 438? Well not in the least given the above C2240!

I have well over 100 MPSA06 (don't ask). I've just measured a random sample of a dozen or so. Many are loose, and many are on bandoliers. Measured on a Peak DCA75, all the ones I measured were in the range 135-180 at 5mA Ic. 438 seems high. But Mouser is a five-star excellent supplier - I've used them for years. Although the hFE seems high, it might be an outlier. How did you test it?

I am currently soldering a T2 board. Earlier I asked about the adequacy of Mouser. We discussed the STN9360. Today I took the MPSA06 out of the package. I measured the hFE and again was surprised by hfe= 438. According to the datasheet hfe= 100. I had three PZTA06's and they show hfe=207. I will have to use c2240, they show hfe=241. I am shocked at hfe=438.....

We aren't in the EU and that muddles everything. I'll try that plus I should have some airbrush equipment somewhere. I just made some new stators for my Senn HD6x0 design that I want to try out.

Aumkar suggested to apply it with an airbrush, but I simply put a little on microfiber cloth and wipe it on the diaphragm. After it dries, I buff it off. It’s dirt cheap and working very well.

Share a pic please, once you verify it works. BTW I bought Licron from Farnell, they had no trouble shipping it to an EU country.

Licron is not available here and shipping anything under pressure is a no-go. The Comfort was available at my local store so I'll give it a go. Nice consistency too and dirt cheap.

Thanks @Shawn. I have ”gathered” some info from three sets of 300B, one 2A3 and one 6A3. To me it seems that they behave quite similar and need about 7K – 7.5K cathode resistors. Your 50K trimmer (Grid Pot) will probably make it easier with the “fine tuning”. I guess you have put trimmers on the tube side of the board for easier access.

TBH I bought a can last year and have not used it yet. There's lots of info on DIYAudio. Keep us posted if you try it. Ach, thought you were mentioning Licron. Keep us posted anyway

Interesting, I'll see if I can find that locally. Do you apply it with an airbrush or a sponge?

And so, yesterday was the great day of final close in the enclosure, it played flawlessly for a couple of hours, I came back at it for some music after dinner and PAM! A resistor burnt down with sparks and a flame in the region of DN2540 in the B+ board. Me sad . Have to tear it down again to investigate about arcing or whatnot, a nice picture of the event, so that you can smell that burnt chicken flavour 😁 More importantly, forgot to say that that PAM took along my DAP, as if a 450V discharged to ground suddenly, and my Fiio player (5 yo thanks God) broke down, not to restart anymore. One more thing to repair. 😒 I've seen someone experienced something similar, but mainly in the amp board, never on the HV one. Possible cause?

Paralleling a 3.3k resistor with the original 1.5k gave an effective resistance close to 1k, which I expected to behave similarly to using a single 1k resistor. After doing that, the offset increased significantly from around +12V to about +60V. So in the end, I reverted back to the original 1.5k setting resistor.

Why not use Licron crystal which seems to be the preferred coating for people making ESL speakers?

Can you share a little more details? Any picture what you are using, how much of it?

Aumkar suggested using "Comfort" fabric softener for coating, and I have been using it for a few months now. It works very well.

I’ll have to tinker a bit more and see. For now I’m just shooting native to see what comes straight out of the camera. I’d love to have enough time to tinker with raw files but reality is that I don’t, so I try not to kid myself into taking them and then having to deal with the massive file bloat. Honestly, if they’d followed through with the A7IV this year like originally planned that probably would have been the camera of choice. The A7IV has been game-changing for me. It’s got all the resolution that I need, exceptional low-light capabilities, and was not hard to adapt to coming from Nikon. This stuff is still mind-numbingly expensive but life has moved on to the point where it was not an impossible reach to pick one up.

Iiu Susiraja’s Self-Portraits Are More Than a Dare https://www.newyorker.com/culture/photo-booth/iiu-susirajas-self-portraits-are-more-than-a-dare https://web.archive.org/web/20250721014944/https://www.newyorker.com/culture/photo-booth/iiu-susirajas-self-portraits-are-more-than-a-dare?mbid=social_bluesky

After paralleling with a 3.3K resistor an increase of a few mA seems reasonable, but what happened to the offset?

Thanks for the correction. I actually paralleled a 3.3k resistor with the existing 1.5k CCS set resistor, which gives an effective resistance of around 1031Ω. Based on the measured voltage drop, that gives me roughly 24–25mA of current. I believe the difference might come from my cathode resistor and grid voltage setup — possibly the cathode current is already limited before reaching the CCS. That might be why the current didn’t rise as much as expected even with the lower set resistor.

It was antistatex spray, it was what I had at hand and could use in a small dosage. I went away today and when I arrived home again the imbalance was back. Might not be as bad but yeah, not a good fix.

Because in the UK they'd just be rubbish gods?

Why do the trash gods not smile on me in the same way?

Hey Spritzer, what are you using to coat the X1’s diaphragm?