Help identifying "power rails" in amp layout

[WateryDomestic]

Hello all, not really sure if this is the right area to post this, but need advice from anyone with amp building experience. I'm trying to understand how tube amps work so I can potentially mod a fender of mine, but the handbook I'm reading keeps referring to "power rails", which are confusing me because:

a) I conceptually really don't understand what they do (but get the gist that they transfer DC voltage back to power the tube

b) I don't understand what object in the Fender Princeton schematic the handbook provides is supposed to represent the "power rail(s)". I've included the schematic below. Apparently, the plate (pin 1) of the first triode of the preamp tube is supposed to run the signal through the 100k resistor, said resistor being connected to the "power rail" at some point. The problem is that I have no idea what the schematic is using to represent this "power rail" that the 100k resistor is wired to, nor do I really understand what those "rails" are connected to that is powering them (the transformer?).

Any help from anyone experienced with this kind of stuff will be greatly appreciated. I'm decent when it comes to understanding a system conceptually, but if I can't visualize a component of the system then there's no hope for fully understanding the whole.

[potatofarmer]

Schematics are better for understanding functions; wiring diagrams are better for understanding how to assemble.

Try this: http://vintagefenderamprepair.com/wp-co ... ematic.pdf

What book are you reading? I don't mess with solid state stuff, but power transistors are generally powered by both a positive and negative voltage (+50V and -50V or whatever) for a pair of NPN and PNP.

With tube amps, there's really only B+ (high voltage) and ground. There are heaters as well, but there's not much to talk about there.

In the schematic I linked, high voltage AC passes through the rectifier tube (which has its own heater winding since it needs 5V) which converts it to pulses of high voltage DC that charge the first rectifier cap. The filter choke (and second filter cap) smooth these pulses further so they look more like pure DC, which feeds the power tube's plate (through the output transformer), the power tube's screen, and (through the 22k resistor) the two preamp stages. Current passes through the tubes to ground, which is the high voltage center tap, completing the circuit(s).

Might I suggest reading the free chapter Merlin posted of his book here? http://valvewizard.co.uk/Book1.html

[crochambeau]

This thread took off in gear:

viewtopic.php?f=149&t=50714

[WateryDomestic]

What book are you reading? I don't mess with solid state stuff, but power transistors are generally powered by both a positive and negative voltage (+50V and -50V or whatever) for a pair of NPN and PNP.

I'm reading Dave Hunter's "The Guitar Amp Handbook", and the layout comes from there. I've always been kinda iffy about his tone articles online (Reverb, etc.) because he seems to have the exact opposite taste in guitarists as I do, but this books has been pretty readable for a beginner. One of the only problems I'm having is that he'll sometimes throw out a term (see "power rail") without defining what it is until later in the book, and I'm a very "needs-the-concept-explained-systemically" kind've learner; like the Wire, all the pieces matter to me when I'm learning something new. I'm sure there's a method to his madness though

[potatofarmer]

This thread took off in gear:

viewtopic.php?f=149&t=50714

Thanks; this keeps happening to me. I'm terrible at ILF.

I'm reading Dave Hunter's "The Guitar Amp Handbook", and the layout comes from there. I've always been kinda iffy about his tone articles online (Reverb, etc.) because he seems to have the exact opposite taste in guitarists as I do, but this books has been pretty readable for a beginner. One of the only problems I'm having is that he'll sometimes throw out a term (see "power rail") without defining what it is until later in the book, and I'm a very "needs-the-concept-explained-systemically" kind've learner; like the Wire, all the pieces matter to me when I'm learning something new. I'm sure there's a method to his madness though

It's all in the game.

Merlin's preamp book is fantastic for learning how tubes work. It doesn't cover the power supply, but it does cover everything else about preamps. I think the first version was a little more beginner-friendly, but the current version is definitely more thorough.

The AX84 projects are also good free resources. Check out the "P1 theory document" here: http://ax84.com/p1.html - it covers pretty much every part of an amp that's a hair more complicated than a Tweed Princeton.

[WateryDomestic]

It's all in the game.

Merlin's preamp book is fantastic for learning how tubes work. It doesn't cover the power supply, but it does cover everything else about preamps. I think the first version was a little more beginner-friendly, but the current version is definitely more thorough.

The AX84 projects are also good free resources. Check out the "P1 theory document" here: http://ax84.com/p1.html - it covers pretty much every part of an amp that's a hair more complicated than a Tweed Princeton.

Thanks so much, I'll check it out.

It's all in the game.

Oh, indeed

[crochambeau]

I'm terrible at ILF.

Nah, the filing systems is a cluttered desk is all..

SIGN OF A CREATIVE MIND, RIIIIGHT?!?!

Great links! Thanks for sharing!