Originally Posted By: Simon - PG Music
Good to see you still working on projects like this Billy!

My brother, dad, and I made a project similar to this as a Fathers Day activity a couple years ago. Used black walnut for the neck, with a simple oil finish. No frets. My dad and brother made 3-string guitars, and I made a 1-string bass (34" scale with a single flatwound string and a humbucker pickup).

As some of you might know, I do a fair bit of work on tube amps myself - I've built some tube gear from scratch too. I don't know much about 6SQ7 or 6SL7 though. Sadly I'm young enough that my electronics courses in college barely even taught us transistors, instead focusing on op-amps and other IC's, so all my tube knowledge is just stuff I've picked up through working on guitar amps and the odd tube studio gear.

Gordon's correct about the DC voltage - if you have a 270v transformer and a 5Y3GT, you'll probably get around 330v DC at the output - though this is variable depending on load, wall voltage, and other factors.

How I got to this number:
AC voltage multiplied by 1.414: 270 x 1.414 = 381
The 5Y3GT datasheet tells me there's a 50v drop with a 125ma load

I agree that tubes certainly add character to guitar, however the biggest factor is the speaker, not the tubes. Tubes aren't even second place, the output transformer is! When I'm recording at home, I mostly use guitar amp plugins (in particular there are a couple plugins that let you copy your own amp using machine learning), however I always get the most "real" sounding results when I re-amp through a real speaker, which I usually use a solid state amp for. YMMV though.


This post needs repeating because some information here only becomes known by experience.

Simon, at least in my less-than-humble opinion, you are 100% correct about the most significant factor in the sound of tube amps being speakers.
The "iron" is next. I have a guy in California who builds power transformers and output transformers for me. This is possibly the most arcane and least understood component there is. There are people building custom capacitors trying to replicate the ones from the 1950s.

I vaguely remembered the 1.4?? number...lol Don't ever get old...lol

Guys a lot younger than me are building and experimenting with tube electronics. That world is not going away anytime soon. Some of those guys understand all of the old and new electronics and can program in several languages on top of that.

You can look at the grand canyon on youtube, but that will never replace going there in person.

It is good to hear from you. It has been a while.

Cheers,

Billy

“Amazing! I’ll be working with Jaco Pastorius, Charlie Parker, Art Tatum, and Buddy Rich, and you’re telling me it’s not that great of a gig?
“Well…” Saint Peter, hesitated, “God’s got this girlfriend who thinks she can sing…”