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I understood it so that the cathode resistor change would be more of a voicing option, not to compensate the operating point from the rectifier voltage change, and I was thinking about the preamp. So your reasoning makes sense :) Not even sure how they do it on an actual rectifier...

An OT also has a frequency response. Generally speaking a HiFi OT will have a broad frequency response (especially up to much higher frequencies) than an instrument OT and that is definitely not always desirable.

Cool project, even cooler presentation ;) I'll gladly follow this one! One comment though, if I understood your DPDT idea: I would advise you to do this one as two separate switches. - One for the cathode resistor, and in parallel instead of series. Should have less pop, and then you can use...

Fair enough! Do you reckon it could fit in a "floor amp" type of case?

Interesting! The thermistor I wouldn't worry about the remaining resistance really. Frequent in those situations. The 317 heatsink is pretty small tho, I would have tried to fit a bigger one on... Also, when you say 220k/3k9 gives a "classical" 12ax7 response, is it with the same capacitor...

Doing a LED front panel from your 12V DC is straightforward. Depending on how the standby is wired you could even do a dual Color for standby/on. I went dual Color on my amp for the plexi front depending on the channel I am on. Three LEDs running at 50% of their max power is plenty enough really.

Congrats! Needs some LEDs tho 😁

Is the amp close to an EM source when you play? Computer, monitor etc? From your layout picture, I would say that probably plays a huge role as well. Seems you have your grid stoppers on the pins though so there is that already.

And make sure they area all DPDT on/on/on and a mix of type one and two just for fun.

From what I see from the schematics, there would be too many changes to do it with a single mechanical switch. You would have to build a series of relays to do the changes, and I think there would be some pretty nasty pop even with smart implementation. Probably smarter to try out both...

Could you diagnose where the hum came from before the changes btw? I would say a shielded input to v1 grid stopper is mandatory. Raising the grid stoppers probably did a lot for you there.

I don’t think you can find something off the shelves that is all in one for my specs. Quickly looking at Hammond you could get a 266L14 and a then whatever you like. A 340/50/6.3 is fairly common. You have some flexibility there -330 to 350 will make close to no difference, diffwrent bias...

Yeah, grounding schemes between different regulated DC, elevated, B+ and audio can be hell. I usually go for buses that slowly branch out and are specific for each section and only meet at one point close to general ground. But never dealt with elevated…

Looks great! What are you using the DC for? The Novak and the OP amps?

Is there anyway to hide a thread? You guys are not helping me with my growing tube curiosity... Hoh well, a least I stick with current production 12ax7. For now. Hoh wait a 5751

Yes it’s made so you can choose your solution. No loop (original deliverance had no loop) or whatever after market. Tubetown sells a decent solution for example, just need to tap the B+ somewhere.

Hoh wow that thread still lives! Thanks for the kind words. Yeah for a close copy a PCB works well. And regarding the chassis, if I had to do it again I would just model it and have JLC cut it for me. I did it for my « VH4 » and it is stupidly cheap, even powder coated and thick. Funnily...

Thanks! I am currently out of those but I may get some more next time I order from JLC. If you want I’ll let you know.

-edit: I am leaving those here but I just realised they plain sound bad lol. I’ll take new ones at some point in the near future.- Couple of soundclouds I did fast with my iPhone, so more "room sound" than anything (cough phone on the desk, speaker on the floor not really pointing at each...

I think the EQ for the clean channel, in my user case, is overkill. Properly voiced and a simple Tone knob would probably be sufficient. Nice to have for sure though, sounds great as is. But DAMN that channel 3 is bringing the goods.