Leaderboard

Added a NPN, a trimmer and some resistor. With those it should be possible to set current through output transistors. Well, that’s the idea. If it works I probably let you know…

https://youtu.be/viQx4KDivPY

Don't think about it too hard.

Senior HeadCase member MLA has lent me his Dynahi. A week listening to it have convinced me that one actually can listen to non-electrostatic headphones. So here is my first attempt... ... a balanced something with lsj689 and lsk489. And as always everything I make is based on a Kevin design. In this case on the famous Dynahi.

In a previous post I mentioned the less-than-ideal performance when Carbon is powered by a ±400V supply, and I suspected that the lower Vce on the PZTA42 is the culprit. Now it's been proven. The PZTA42 being a high voltage transistor, has a non-linear region at low Vce, as the slanted curves you can see on the upper left side. With 407V on the negative rail, the transistors on my board works at Vce=8.4V and Ic=20mA, right around the knee. The global negative feedback would have a hard time correcting that non-linearity. It also explains why some people prefer setting the Carbon at a lower current when powered with ±400V supply, as it also improves the linearity of the PZTA42, albeit to a lesser degree. I guess Kevin chose the high voltage PZTA42 to deal with the power-on transients. I have a quick and dirty fix. Just bias the SiC MOSFET a little higher to give the PZTA42 more headroom. The SiC MOSFETs are biased by two 175k and an 20k at the gate. Reducing either 175k or increasing the 20k would do. The goal is to move the PZTA42 operating point to the right, well into the constant-current region (parallel lines). I would use Vce=14 to 15V. Pushing it even higher would increase the power dissipation on the PZTA42, eat into the max output voltage swing and have diminishing return. What I did was to put a 260k resistor in parallel with one of the 175k resistors. YMMV because it has to do with the operating point of the PZTA42 in your circuit, the Vgs(th) of your SiC MOSFET, etc. After the quick fix, one of the channels now measures as good as with the ±450V supply. We can see that the max output voltage is slightly less compared to with ±450V supply. The difference is subtle with the log scale, though. Now I'm continue to work on the other channel and see if I can find something else.

I did! Several, in fact. Moldova's a small country, so I got to see quite a bit of S.

Did you get a picture with Blinken when he came through?

I'm a little late to this game, but hoo boy were folks here spun up about that. I kept thinking to myself -- "no way Putin let Lukashenka have a working map."

From the link above it looks like Maersk isn't the only shipping outfit to pull out. It might be the biggest though by a decent margin. Nestle's position is totally untenable. That it is "only" supplying "essential" items like baby formula and pet food to Russia misses massively the point that a number of Ukrainian cities are under siege, the population is starving, and have had no power, food or potable water for weeks. And they are having seven kinds of shit bombed out of them daily. Well Mr Ulf Mark Schneider with your $20m salary - how about some essential items for Ukraine? And how about pulling the plug on Russia, like over 400 companies so far? Bastard.

Nestle purposefully reduced protein in fucking baby formula sent to Africa. They have been on my shit list for a while. I didn’t know Blue Bottle was Nestle.

Indistinguishable from Cat Power's covers album. Which is a good thing.

I'll give up California Pizza Kitchen, but I won't give up Maybelline.

Nope, not a bit. I can confidently say I currently consume 0 products on that list.

I was wondering if it'd be worth watching, thanks.

This interview is amazing. I listened to the whole thing last night, and repeated large parts of it. The ending is particularly scary.

I only changed the LT1021 with the cheaper LT1236-10. The latter has the same performance as the LT1021 except the long-term stability which we don't need. Oh, and I used the DN2540 in TO-92 package for lower cost. Nothing is different from the original circuit electrically. If the output of the GRHV is low, chances are the passing element (SiC MOSFET) is not damaged. A series linear regulator such as the GRHV is probably the easiest circuit to troubleshoot. Jut need some electronics basics and a lot of patience...

HAPPY BIRTHDAY!!!...

Happy Birthday Al!

Very belated best wishes Al - hope it was a spectacular day!!

I'm glad to report that both the GeneSiC G2R1000MT17D and the Microsemi MSC750SMA170B work well on the KGSSHV Carbon. The G2R1000MT17D works on the GRHV, too. The overall performance of the Carbon is stellar. It's virtually distortion-free to about 200Vrms at the output, and maintains very low distortion up till 600V!! You want the ±450V power supply for the Carbon. With ±400V I ended up with something like the following. Still not bad but not as brilliant as the curve above. I figured the PZTA42s are not quite in their linear region because of the reduced Vce. A word of caution is that both SiC MOSFETs are somewhat 'fragile' compared to the Cree/Wolfspeed C2M1000170D, especially the G2R1000MT17D. I killed a few when matching them on my curve tracer. I guess the Left-right switch on my curve tracer doesn't guarantee that S connects first, then G and then D. No more failures after I connected a 10V zener diode between G-S on the test fixture. An expensive lesson learned😅

Happy Birthday!

Happy Birthday!

Happy Birthday, Al! Hope it's been wonderful.

Drone Mass Johann Johannsson

Nearly finished casing my Salas phono stage. Need to mount the transformer and raw PSU. I may use a vandal switch on the front, but some type of momentary switch board or at a minimum, a voltage select board will be going in as well. Also need to shorten transformer leads, and clean up wiring. Runs dead quiet in my system; no noise evident when turned up all the way at tweeters or via headphones. I've got the Antek steel transformer cover and a set of Mundorf Supreme caps, though the kids all seem to be going for the Clarity Caps these days. It sounds good with the BC polyprop and MKP1837 I have in there now. This is setup for MM at 42dB gain. Loading switchable to several different values via dip switches. Set at ~34K right now for the Ortofon 2M Bronze I was using (a bright cartridge IMO).

I’m way late to the party but the Netflix F1 show is quite good.

I missed this a couple of days ago courtesy of Covid - but the JWST has reached full optical alignment. The alignment object is a star well within our own galaxy, and you can see the 6-fold diffraction from the hexagonal mirrors. It is only visible because of the extreme brightness of the star. But everything else you can see are galaxies - right down to the faintest streaks you can pick out. This image is a tour de force of stunning optics and an astonishingly complex machine.

96 year old Boris Romanchenko, survivor of four different nazi concentration camps killed last Friday by the Russians in his home in Kharkiv.

https://www.nestle.com/brands/coffee/blue-bottle-coffee If anyone here is interested in stopping their patronage of Nestle (see the comments in the WW3 thread), this is important info -- Blue Bottle was acquired by Nestle a few years ago and is still owned by them.