DC Offset Issue in Don Sachs Preamp

It’s the rectifier tube. Don will tell you tot always power amp down first than preamp. 
I know because I had the same thing happen on his preamp and he told me it’s completely normal. Pre on first, wait 1 minute, then amp on. Amp off first, then pre. 
This is normal, no worries. 

Yes. Amps on/off first per Don. (For the Raven/Blackbirds) My one word review of the Raven/Blackbirds would be. Get. 

Thank you everyone!  Lynn, you are the man! 
 

don’t tempt me on those new models! 

Don is awesome people and one day I aspire to have enough saved up to buy his great products (And Lynn Olsen too for that matter).

Here’s proof that Don is "Alive & Kicking". Another awesome fellow Canuck (for a West Coaster anyways)

https://youtu.be/iUk0vc9FyXY?si=KtsNDt2KD1ze8jlS

Actually, posting these little "how-tos" on the forum is good for me, since the content can be added to the product manuals. I’m the one that writes them for Spatial.

Plenty of experience writing these things ... nine years at Tektronix in Oregon, followed by several years of editing Glass Audio and Vacuum Tube Valley. So it’s just keeping in practice.

Many of my designs are "thought experiments" to see if an idea works or not. In audio, you need to physically build something to hear what it actually sounds like. Before it’s built, it’s a sound you hear in your head, but it’s always a surprise to hear it for the first time. That’s been my experience since the Shadow Vector intro at the 1975 Chicago CES to hearing the Raven intro at the Seattle show in 2023.

(By the way, I am the owner of a DS preamp. Great design, and yes, I know what's inside.)