joehpj

Sandwich.

The name always remind me this.

I always wanted something that can beat T2 output power. 2SC4686 has been obsoleted and need 3/ch to do 500V/20ma. I check the datasheet, c4686 has 2.2pf output capacitance so it will be 6.6pf in total. Fairchild announced SiC BJT but was never available on the market. GeneSiC has some available on the market with some silly price. Among those, this has the lowest Coss. http://www.genesicsemi.com/images/products_sic/sjt/GA04JT17-247.pdf 16pf Coss about 2.5 times than c4686. But I don't know why this thing should be BJT(alike?) but those pin out are labeled as DGS. BTW. series caps are need for 600V and means we'll need 4x caps than 450V to get the same capacitance. Much more expensive to build. I don't know if this has that much difference on the sound. Normally no one will and should drive it to clipping.

I googled for some substitute for c4686 which has been obsolete. And found MJW18020 seems to be a nice current production one. 1kv Vceo with much higher Pd makes it easier to do 500V 25mA. Any thoughts? Edit:No. output capacitance way too high.

I wonder if it's possible to add a voltage dropper like megatron did to lower 1156 and 5026 Pc and push the output voltage a little bit further? Say 475V~? ( I assume 10M90S+DN2540 can take 950V in total to be safe.) Or even -500V since EL34 output will need approx 35V across the tube.

Ahh... light speed. Hat off to Kevin.

I like the top cover.

Lampizator......... Errr....no

Different circuit though...

So with T8000 input and GG output, we could have something tube in tube out.

But...all other stax amps have description of DC coupled on their website. T8000 doesn't. I was wondering if this amp is DC coupled.

Joamat used it since it since 2.5 years ago, so it seems stable. Or maybe he used some other parts? Or be careful not to crank up the volume too much

10M90s has 900V max voltage. How to use it on T2?

Seems to be something AC coupled rather than DC coupled as they did for the past 30 years. Unregulated PS? Seems so.

But mid point of megatron seems to drift quiet a bit. Is that because of the tube ccs?

Push'em harder! 20mA at least

Those were a GB ang728 and I ran locally. It was supposed to be silver, or grey, or gun metal - at least in our imagination. We ordered something like that. When the factory gave us some pictures of those...Say 30 of those. It's simply too late. It was done by accident and I assume it's impossible to reproduce again. I believe something was wrong in that anodizing sink. Who knows. I love them a lot. Because of the color, the power indicator is also green.

Those are indeed from China. I have some spare.......so PM me for detail if you are interested .

I copied from carbon BOM. Those are bypass cap so use whatever you want/have. My bad. should at least >400V to be safe.

Here are my BOM for a pair of BH. https://www.mouser.tw/ProjectManager/ProjectDetail.aspx?AccessID=b44788bc7f for GRLV and GRHV. copied from Carbon build thread. http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b6d687c7f7 http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=54687aa8fa Parts I already have or going to buy from local dealer are NOT included like LEDs, insulators, IC sockets. Someone need to check if all resistor value are correct. I hope I could finish it at the end of April

I think the final casing of the VR was done by same factory. Mine uses dale resistors. Or maybe they are really the same thing. I don't know (and don't care). I only care about the performance which was pretty nice for the asking price. I will have a chance to compare it with DACT. Will report if the difference is significant. I haven't heard GG now. It has been back ordered for months. According to the builder, both carbon and GG are TOTL amps. Overall performance are in the same league. Compared to carbon, GG has slightly recessed bass and tremble extension but sweeter mid and vocal. I've heard some people said 009 w/ carbon were too "clean". For those who think so, GG might be a better choice.

Semi-customized. The shape of front plate, depth, height, and heatsink was fixed. Others were customized. If you use my BOM, that would be 10k/.5w as you used. A experienced builder told me grid resistors were super hot because it was connected to the internal structure of tube. I later changed to 470R/3w, just because I have them in stock. KG said the value doesn't really matter. T2 used 20k. BH used 470R. Those were not EIZZ. Those were indeed from China. Building quality was good enough for the price. No issues like pop or clicking . There weren't much choice for stepped VR that were cased and no clicking. It has more steps in low volume area than DACT. Khozmos clicks. Goldpoint is expensive. I've bought over 10 of these. For long wires, as you could see, there's no place for extension rod. Even I could move the amp boards a little bit, it would still need to redesign the back plate that means I have to throw away the whole batch. The wires were shielded and power supply were in another box. No worries.

Just like Carbon we built. Same box, same PS. Relay=120s. Separated filament transformer.

Chassis are semi-customized and buttons are also from the manufacturer. Separated PSU theoretically would prevent 60HZ AC noise. The reason I use separated box was much simpler.... Because it's hard to fit GG in one box or it would be HUGE. Since customized chassis has MOQ, I want carbon, GG, BH to share a same design to lower the cost of customized chassis. I had to order a batch of those. So yeah, more amps coming.