I was hoping it may be anything inside rather than the output transformer, it would be easy for me to just rebuild it without that Pcb as at this point I know I wouldn’t mess the connections. Well, I’ll switch the transformers yet to at least have this one confirmed and then if it won’t move I’ll pull that pcb off and rebuild the whole thing. Thank you 🙏

Yes, at this point only two options have left for me to check, moving the voltage regulator close to the pins of 300b and swapping the output transformer to see if those quiet pops and bursts of hum will move with it (I really hoped that it wasn’t that one, but well, I’ll see). Thank you for taking time to answer me,

The transformers (excluding the output ones) are as per your specifications Hammond, caps are tantalum and so on. If it happened to both sides I would start all over again, but somehow it is always the same side, the other is dead quiet, hum free and no cross talk, and plays perfectly ( the side affected plays good too, beside that( not even laud) hum and cracks and quietly making the tubes dying without any signs. I understand everything has importance also placement of the components, but would that be this in this particular case? That would very much surprise me, I’ll try to move that one regulator to the pins of 300b and see if that changes anything. Thank you. …one more thing I forgot to mention, I have never wrote that “design has a problem” rather than that, and this is I guess obvious, it is my built that has a problem.

Yes, I’ve got that printed at jlcpcb cause I just wasn’t sure about my ability to manage safe connections and fixings using wires, I know I made mistake at placing voltage regulators ‘far’ from the pins of 300b, I measured the one with longer trace and it drops to 4..87, the other that is closer (left valve) drops too, but only a fraction 4.94 it looks like the difference in distance causes the difference in voltage because at the points of regulators voltages are the same and 4.98. The valves aren’t matched, I bought a pair from uk hifi collective psvane, they were ok till one has gone dead just like the previous from AliExpress, so I ordered one more from Ali and now use the unmatched (one hifi collective and one AliExpress ) only to be able to work the things out and be sure that all works correctly.

Hi, so after some time and another dead valve I brought down all the voltages by using the resistors and diodes before high voltage pins in rectifier valve, used 5U4GB, and two resistors to drop that filament for 6sn7 and now the voltages are mostly in the spec, apart that 2,5v at LED is 3v, at both sides voltages are exactly the same yet the problem with the left valve seams to stay unchanged, I can hear little hum, pops and cracks coming out of the speaker, I have a feeling that most probably after few times turning on and off that 300b on the left will be dead again, well, I don't know what else could I try. I’ll see how it goes this time.

Hi, so after some time and another dead valve I brought down the voltages by using the resistors and diodes before high voltage pins in rectifier valve 5U4GB, and two resistors to drop that filament for 6sn7 and now the voltages are mostly in the spec, apart that 2,5v at LED is 3v, at both sides voltages are exactly the same yet the problem with the left valve seams to stay unchanged, I can hear little hum, pops and cracks coming out of the speaker, I have a feeling that most probably after few times turning on and off that 300b on the left will be dead. well, I don't know what else could I try.

thank you, I'll try that option and will share the results.

I finally turned this thing on and after burning down the rectifier tube, with a replacement it works and to my amusement really well, no hum whatsoever, the sound definitely special, I can't say much else as it's my first experience with tube amp. The numbers are a bit higher than stated in the schematics: the heaters of 6SN7 are 6.7VAC, the LED to pin 3.3V, the 3-5 pins 101V and the B+ 445v as the Anode 435V, generally all readings are higher apart of heaters for 300B which are perfectly 5V. When I first checked this with the current limiting bulb and variac it all was much lower than in the schematics even with 230VAC, yet my first readings without the limiting bulb were even higher, than those given here, but I managed to lower it by chenging the PS primary from 230V to 240V(I live in UK, but in my house it's 245VAC!) I will try to deal with this sometime later if I get any idea how to do that, anyway I'm surprised how good (for now) it all works together with Ear834 and JBLs4410A and how loud it is. Thank you once again for all the great videos and sharing your knowledge and experience, without that this build would never happen.

took long time, but near to be completed, waiting for the last part, the 300bs

after watching the videos I decided to go with 300B budget. still some work to finish it, waiting for output transformers.

Hi Henryk, very nice bild this one. I'm curious about the transformers you have used, the Edis, are you happy with their performance I mean the output ones, would you mind sharing what model are they exactly? All the best. Phetrus

Now I’m thinking of pairing it with the best possible for me option for amplifier, maybe Skunkie’s 6SQ7/EL34?

Thank you so much, I love to watch your youtube channel, great work.