hyperma

I guess the real circuit bit different with the official circuit pic. I got this from internet: and back layer: then align layers with through holes and apply "overlay" on top layer got this: It's easily to redraw copper route and add on BJTs polar sign: Finally got this: Hope it does work in simulation, my Multisim collapsed need to be reinstalled.

The 2SC5460B is back, renamed as TTC5460B, a TO-126 packaged 2SC6127 given us more possibilities on construction, maybe it's time to start a new project?

Yeah, recently lots people chasing the upa68ha, thinking its a perfect replacement of 2SK389 or 2SK170s pair, but it's not, most Jfets unable to provide Yfs as good as 2SK389 which is 22mSiemens, re-bias will cause cutoff too early. JFE2140 is a better choice, just bought 1 meter last night, I will try to put it on the cartridge amp see how it works.

I have tried every possibility to optimize the circuit, but finally STAX has chosen the worst one. I'm pretty sure that STAX has gone with SMDs, it all fine, most parts in working will not generate lots heat, also SMDs significantly reduces the distributed inductance caused by PCB board through holes. ...... there some analyze and questions: 1, 4 large sized 7W 47kΩ resistors work as plate loads for 6SN7s, but higher value must be better, for example, two series 33K as 006T, or at least 62K 7W will far better than 47K, because 47K means too much current flow through 6SN7s, in my simulation is 9.5-10ma (grid at -9V), it's fine for 12AU7 or 12BH7, but 6SN7GT....hmmmm. 2, There are limited choice for input differential Jfets, I like using Toshiba 2SK2145 in my design, but the common sink package doesn't work here, also there are SMDs, so I guess they would better swapped to HN1C01 BJTs from Toshiba, the same thing may happened with Q6 and Q7, these components might be replaced with TTA010. Don't ask why not BC846BS, they are Japs......, local brands first as always. 3, In simulation I placed two 1815s on Q8 and Q9, but if you want to save cost and place, 2SC4944 will be better, by the way, you can also save 1 100Ω resistor due to the common emitter design. 4, The negative rail load R19 perhaps still wafer resistor in real life, which power dissipation will reach 500mW, hope they put a large size here, don't let the T2 tragedy happen again. Extra: I didn't see any improve on original 006T or T1, there are nothing wrong with 6FQ7, the 6SN7 only consume more filament current and......in some old Chinese 12BH7s, they only swap the glass package to 9 pins, inside stuff was 6SN7 or 6N6, so in my opinion , most modern 6SN7=12BH7=6FQ7......so use 6SN7 in 700T is pointless.

measured by a high voltage probe of oscillator, yes ,you right, the bias has fallen down when the probe touch the bias connector. I drawn this pcb by AD11 and made in JiaLiChuang, which has two factories in south of China, cheap and quick.

Hello everyone, hope everything doing very well today. Few days ago I found two transformers in my dungeon, which named by my wife. I mentioned it has 16V out and double 110V in, so I guess perhaps could make something like stax srd-7. Then I made a pcb and give most places to voltage doubling rectifier, as same as srd-7, and... it works. Well somehow the bias unable to reach 580V, only around 490V, the sound quality, of course, bass section bit weak, so I have to turn the EQ on, then everything fantastic. BOM: 2 30W transformers 110-0-110 in 16V out, 1 50W transformer 220V in 110V out. 1 fuse @200ma 6 0.1uf 630V caps 1 0.01uf 630v cap 6 1n4007 diodes 4 speaker connectors 2 2M2 resistors @ 2W (for safety consideration no less than 1/2W) 1 15k resistors ( to light up led) 2 5R resistors @5W for dummy load 1 1M resistor 1 stax standard electrostatic can connector Infact if I could spend enough time on it, hand wired construction must be better and cheaper. So I call this project "Ghetto SRD-7".

Great great appreciate for your help. DN2540 is gone,reverse leakage been found,stable now.

Assembling another kgsshv carbon, this time the positive 400V keep droping from first second, don't know why. Any diode or mosfet leaking? Don't know how to simulate. The tantalum cap or pair ksc5026s area about 95c, or 203F, hmmmmm....

Sorry,the first stage 12au7s to drive 12ax7.

Probably because it's an electrostatic amplifier, the first stage needs provide 24db gain to drive pair 12au7s ,otherwise unable to reach amplititude.

Not making anything yet, but planning. After the Carbon I guess Megatron will be the next,so... A Megatron on more Old school style...not finished yet

It's true, for diyer, Mouser, RS , Element14 or TME etc are best choice. Few month ago,I have bought some FAKE PCM1704s, of course they didn't work. The best way to find out who they are , is disassembling.....by fire, on microscope , I saw HC574 and TI mark on the die.......What a joke. Another example was my personal favorite op LM4562, I got some on same way, and matched their dies with AD744, remarked for sure. Also funny is in China AD744 is more expensive than LM4562 now. Hell......but seems Kevin already known everything about fake parts.?

The price ..... worth that risk, AK4497 $35per/100pcs and $5 a package of TIP122(500 pcs).

To be honest, I don't have much EXP on this, but 40 USD is enough to afford the alumium amplifier case with heatsink......few weeks ago I took a relay pcb from garbage bin,it's working on Carbon(or more carbon) now, don't you want to make your own one?

Finally, well, I have fixed the "KG Carbon - more carbon" ......,in beginning I wanna make a "more carbon and lots cheaper version",but see what I got: DN2540 and IXCP10m90s I have bought from taobao.com......are fake, now show you guys photo: Fake DN2540(yes, I have bought all of them for testing): simply them didn't work ,that's all , I can read 455V from multimeter though probe touch the headsink,but....nothing happened, until I replaced the replica silicon: Mouser version: Taobao - Save your broken heart also bit expensive version: Now the IXCP10M90S time: Left: mouser Right:You don't know who I am version