Designing my first tube guitar preamp: a few questions

[tedmich]

Ive decided this would be the best approach for now, to experiment with what I have available and not be so dangerous as 250+ volts. Im just going to play with a single tube for now to learn some things. I dont have a 6v transformer though, would I be able to power the tubes heater by using 4x AA batteries for 6vDC? If so is there anything special I need to know about connecting one in this fashion, any resistors in parallel with it or will a heater in series with 4x AA batteries work just fine alone?

can't really get much current from AA I think, 1.5 Ah, so 5h max on a single 12ax7 and 4 duracell AA...and they cost what $5?

it is totally clean DC voltage though, nothing else needed, all tubes used to use batteries, even for the high voltage B+ (thus named)

Lots of cheap transformers...an old wall wart, at Goodwill etc
scrounged from an old dead piece of equipment, etc.

or bought here:
http://www.alltronics.com/cgi-bin/it...6A-Transformer
$4!
Later add the WPDLPT transformer from Ted Webers site for $20.00, it turns the 12VAC from the one above into 260VAC,
https://taweber.powweb.com/store/pdlptsch.jpg
plenty for a 12ax7 preamp , Firefly etc
also see Ax84.com, its where I (and many others) began to learn tubes!

[dai h.]

hi, you should check out this site if you haven't already. Tons of old technical books on tubes from beginner to esoteric:

Pete Millett's DIY Audio pages

might also look for jack darr's book online. It deals with repair so might be helpful in gaining understanding or getting things to work.

[tedmich]

hi, you should check out this site if you haven't already. Tons of old technical books on tubes from beginner to esoteric:

Pete Millett's DIY Audio pages

might also look for jack darr's book online. It deals with repair so might be helpful in gaining understanding or getting things to work.

good sources Dai h,

I also found the Navy's electronics training manual (NEET) on tubes is a very good intro and fully online here:
http://www.tscm.com/NEETS-v06-Tubes.pdf