TRANSFORMERS:everything you've always wanted to know but...

hey peeps
I thought i'd start this thread because if need to know someone else out there does too...
(plz consider info offered for the layman/newbie/me... hehe)

Transformer questions:

1 how do you determine the proper input / output trafo for a certain tube type or tube set?
2 what are considerations for type of input eg. guitar , mic, line, balanced, unbalanced...?
3 can anyone elaborate on the subject of trafo ratios and how they relate to any given tube set?
4 without a schematic, how would i determine the correct phase of a balanced input/output for xlr connection? (BTW this will help me with my ba43/ba45 units)
5 how would i determine the proper power transformer for a given tube set?
6 why are seperate filament transformers used in some designs?
7 it seems a lot of vintage gear is elaborately laden with huge chokes, why is this trend not seen in slightly more modern designs?
8 i see a lot of different plate voltages: just how many are there ... what are the most common?
9 is a filament voltage always 6.3v
10 why do some designs have seperate filament for the power supply/ rectifier tube?
11 we see a lot of success stories: anyone have any warnigs/war stories/b+ near death experiences/ pics examples/scientific websites etc.. to elaborate on the dangers of DC voltage for newbies.
( hey i wonder how fast it would cook a potato haha lol ...or more seriously someones hand...hmmmm...not so funny)
I can't think of anymore right now.
everyone please add to this thread.
**ALSO** it might be a good idead to keep questions numbers consecutive for reference in the future.
please continue the number system i have started above.
thanks
Toobie Snack

Detailed answers to those questions would fill a very large book.

Much has been written on the subject. It's better to do some reading on your own than to look for in-depth treatment on a message board. For a very good overview of the whys and hows of audio transformers, read Bill Whitlock's chapter in the current edition of Handbook For Sound Engineers.

It's also worth your while to download and study the transformers chapter from the Radiotron Designer's Handbook, 4th edition. You can find it on CJ's page and also near the bottom of Gyraf's resources page.

And don't forget CJ's excellent META:

http://www.groupdiy.com/index.php?topic=467

Lotsa good stuff there!

:thumb:

Mark

don't forget" they are more then meets the eye" :green:

THANKS MARK

TOTALLY SWEET!!

and CJ.... damn..... what can i say
if info was a grain of sand you'd be a mountain. special thanks <nyd too

now thats what I'm talkin about :grin:

keep it comin
as the proverb goes:

"a tiny drop of rain is powerless until it enters the ocean and become part of a mighty force"
.....let it rain

thanks Sooo much
Toobie Snack



**ALSO**"behind every obstacle lies new opportunity" difficulty is a blessing for the for those eager to solve them.

One question you're not likely to see answered in the literature is why earlier equipment is often built with a lot of large chokes in the power supply, while modern equipment is not.

The main answer is that back in the old days, large high-voltage capacitors were either non-existent or very expensive. A can containing 40-20-20-20µF at 450V was par for the course; the alternative was an oil-filled cap, 20µF or so.

Getting adequate filtering for a power amp out of caps this small was essentially impossible, so designers turned to filters incorporating chokes -- either choke input or cap-choke-cap. Hard to believe, but it was easier and cheaper back then to buy a big choke than a big cap, and more reliable too (chokes didn't dry out). Chokes also have the advantage of limiting current inrush on turn-on, an issue with tubed rectifiers.

These days, with big electrolytics easy to come by, and chokes expensive and hard to come by, chokes have fallen into disuse for the most part, but they're still a good way to go if you have the room, can find the choke and know the arithmetic to design with them.

Peace,
Paul