There are to much options for volume control and power supply.As expected, sorry. It is often assumed one can not hear RF so it is not an issue. EMI and RF are nasty in audio though and in semiconductor stuff sometimes the cause of "listening fatigue" and this intermittent or depending on the time of the day/temp etc. Even when devices look nice and have blue LEDsNot measuring = not knowing.
BTW I do like your design so no negative criticism except a few quibbles like lacking volume control and PSU. Nice design.
For the tube preamp are a lot of applications where you do not need a volumecontrol. Such as outputstage for DAC or CD player, or inputbuffer for classd amp.
About the power supply i started a thread in the power supply section https://www.diyaudio.com/community/...s-design-for-tube-preamp.388367/#post-7073834 to make a high voltage preamp smps. I think about linear supplies there is a lot to find here on DIYaudio. I myself also used in the past the maida regulator or a LR8n regulator with or without fet.
In this thread i like to talk only about the preamp.
I just realised there has been no discussion about heater elevation and looking at the schematic the heaters are floating unless you connect one side to HT0V somewhere. With many of the tubes you could use in this circuit, their Vhk spec is may be low for the upper triode if the heaters are grounded with a 265V HT voltage. The normal solution is to elevate the heaters to around 25% of the HT voltage.
Cheers
Ian
Cheers
Ian
Yes, some tubes will be OK others may not. You need to be careful with a regular 6DJ8 for example because the two triodes have different Vhk specs, but if you use an EH6922 instead you should be OK. Just something to be aware of.
Cheers
Ian
Reproduce luxman cl34 heater supply and heater wiring It's totaly silent and it has a small secret that will help you every single time you meet weird constraints! By the way...you can go opposite way too, lowering the fillament potential below ground!
