To that end you might like NOS Tung-Sol 6550.

I talked about them a bit in this post: https://www.head-fi.org/threads/zmf-aegis-official-thread.972476/post-18129732 Long story short, they should work but the scales for the curves in the datasheet are so large it's difficult for me to say whether or not they will bias correctly. If...

I think it just depends on how they operate in your local area. I've had very few problems with them. I often will redirect a package to a local FedEx pickup location so I don't have to worry about missing them at home.

That's convenient! Just make sure they are TO-220 package and 3.3V model.

Yeah same idea. I had thought to add a load resistor for when no coils are connected (similar to R1 in that schematic) but figured we'd discuss that if this is something @tommyc wants to pursue. At some point I might just put together something like this myself, just don't know when as I have...

Matches your hutch(?) perfectly!

Sorry I'm working night shift this weekend so not really able to respond quickly. That might work, but you're going to have a ton of ripple. My opinion is to use a 3.3V LDO regulator. There are lots of options and they can be very cheap, a simple 3-pin regulator in a TO-220 package, a bridge...

I felt that way for a while, thought having the best-measuring and clean DAC paired with tubes was the way to go, but then I heard a few tube DACs and decided I needed to build one! But it all goes in cycles, now I'm wondering if I might be interested in having a non-tube DAC in addition to my...

I made some edits above as I realized my napkin math was for a bridge rectifier instead of a full wave. The theoretical output current is higher, so the B+ supply could in theory run the coils. But I still don't like it for reasons I outlined above (namely, putting more work on the tube...

Just started glancing at this, there are a couple issues right off the bat. For one, if you are pulling the voltage off the B+ supply, it is going to vary somewhat depending on what rectifier you are using so they have different Vdrop values, unless you decide to use specific rectifiers. Two...

Well the main ZMF cable I use is 1/4", so I either use LOW or MED on 1/4", either one is fine just depends on what kind of damping ratio you prefer! Probably LOW gives more low end control, whereas MED might be a little more airy. I tend to use MED more often. Output Z for LOW with stock...

Just a reminder to anyone running Susvara or Tungsten on Aegis: if you want the most juice for those demanding cans and proper damping ratios, my suggestion would be to use the XLR output, LOW setting for Susvara and MED setting for Tungsten. That gets you between a 5:1 and 6:1 damping ratio...

I'm apprehensive to recommend them since the triode curves in the datasheet would suggest they will bias over current. Now they were tested in the DIY Aegis and that wasn't the case, but given it's a sample size of 1, I'm not 100% confident that will be the case with another sample.

Simpson meters arrived, little guys.

Flat.