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Old 29th July 2003, 04:38 PM   #1
weirdo is offline weirdo  United States
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Default transformers

hiya-brand new newbee here - i know little so please mind that and what i do know i'd like to use Anyhow...like to build a tube amp someday,of course,and know that trannys are usually the most $$$ of the build ,may one use trannys from tvs/computer monitors/large copiers(laser copiers)? i've noticed several T's that have lots of multiple leads,such as in some tvs,on both sides of the unit,whereas others have 2 on one side(120v) and several outputs on the other. the later makes sense to me,but the first type How would one,if he could,measure the outputs w/nothing but a dmm? i know i could measure if the unit it was comming out of worked,but it don't,etc.,etc. also,how to tell which wire is common/nuetral @the output? ie:got two=one has 4 wire out(2 blue,2 red),and the 2nd has 5 out(2 blue,2 red,1 black). my neighborhood library is the size of a peanut so there's nothing there and been having trouble finding something in laymans terms @the bookstores(obviously want to read thru first to see if their "dumb" enough for me b4 buying). i've got numerous pots,caps,resitors,etc., just need to find some transformers and then tubes to match or tubes then trannys,whatever i'll be waiting for enlightenment,thank you all very much
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Old 29th July 2003, 04:58 PM   #2
SY is offline SY  United States
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It's actually the output trannies that will set you back the dollars. You won't find those in a television.

Tube amps carry dangerous voltages. They can bite. I'd strongly recommend that if you haven't built one before, start with a well-proven kit. You're more likely to get something satisfactory, learn something in the process, and survive the experience.
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Old 29th July 2003, 05:23 PM   #3
HDTVman is offline HDTVman  United States
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Ya, What SY said.

The output transformers in a tube amp are designed for that use. Power supply transformers, like what your talking about would perform badly as output tranformers. If you could find one that had windings that might work the core type and materal would be all wrong.

Your much better off starting with a kit if youv'e never worked with tubes before. 8 to 10 watts is likely to be more than enough and 2 or 3 may be all you need. It depends on your speakers and how loud you like to listen.

They can sound very good. I've been at this for many years and use tube amps some times and solid state at other times. It just depends on how I feel and what's spinnin' 12" LPs just screem for tubes or at least I think so. CD's it depends on the music, and for HT 5.1 solid state just because that many tubes would overwelm the AC in the house. ( I run about 1KW RMS or a little more for HT.)

Later BZ
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Old 30th July 2003, 12:24 PM   #4
weirdo is offline weirdo  United States
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so now by "output" trans. you're talking about the matching trans. for the spkrs?spkr=output. or..does a output trans. power up the individual tubes? i think i found out how to correctly measure the out voltages on some of the trannys i have. i have some antique tubes amps from radios(consoles/shelf units) so i am somewhat familiar that they can kill me(not by xperience,though),i've checked out this site and others for ideas/schematics and such and read whatever i can find and because of this and the parts that i can find/have,i don't particulary want to spend more than i can-so if i have to spend $50 or so on a tranny as opposed to $125+ on a kit-i guess i will have to. all that trouble of finding what i got and i can't neccessarily use it
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Old 31st July 2003, 03:41 PM   #5
zobsky is offline zobsky  India
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i'll try and put every thing in perspective

the power transformer converts your mains AC to a high voltage for amp operation (300 V or more .... AC)

the high voltage AC is rectified to high voltage DC via a rectifier tube or diode bridge

this voltage is used to power the amp / pre-amp by adding an amplified signal (AC) component to the DC. The AC component is fairly small (low voltage) and is what will drive your speakers but the DC component remains high voltage. this is fed to the primary of the output transformers.

since transformers only pass AC on the secondary (blocking DC), the secondary leads of the output transformers will contain only the amplified AC component of the voltage.

there are 2 main types of output transformers depending on the amp topology (push-pull and single ended). If you intend to cannibalize stuff you have, you must first find out what they are.
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Old 31st July 2003, 08:11 PM   #6
weirdo is offline weirdo  United States
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now that's what i need - to get somewhere,thanks. may i quiz u some more?
So it goes from ac wall outlet to trans. to higher ac to rect.tube/diode bridge to high dc to pre/amp to speakers?
1.correct?
2.how high is the dc?
3.the dc powers what exactly? and the ac?
4."but the dc component remains high voltage.this is fed to the primary of the output trans." So this high dc feeds the output trans. which turns to ac,or just passes what little ac there is,and then feeds the spkrs?
5.ok=2 types of output trans. - 1 for push/pull, and 1 for single ended. How to determine what is suitable for what?
6.the 1st power trans. can be any trans. as long as the voltages are sufficient? Possibly using a second trans. (of a dif. type,of course,and smaller) for powering up the tubes?
7.again-sorry,i'm a newbie....i do have a basic understanding of electronics and such-i just need it dumbed down a bit.
8.thank you for all of your help! Some of us really need more of an understanding before starting something on top of learning in the process and although making mistakes is the best way to learn...
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Old 6th August 2003, 03:31 PM   #7
weirdo is offline weirdo  United States
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good answer-thanks! i'm outta here.
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Old 7th August 2003, 05:04 AM   #8
zobsky is offline zobsky  India
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definately healthier for him to get a kit, ......
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Old 7th August 2003, 07:03 AM   #9
SHiFTY is offline SHiFTY  New Zealand
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My explanation:

A stereo tube amp ususally has three transformers; two outputs and a power.

Power transformer connects to the mains, the secondaries are usually 5V, 6.3V and 300 to 800V (approx) centre-tapped. (800V centre tapped is often written 400V-0-400V)

This is rectified to provide 200-800V (approx) DC to power the tubes. Tubes run on high voltage, but use a 6.3V heater to get the electrodes warm.

The output transformers may be push-pull (two output tubes per channel) or single ended (a single output tube per channel). The secondary of the output tranny connects to the speaker, the primary connects the tube to the power supply.

Have a look at some tube amp circuit diagrams, it is pretty easy if you "get" electronics. Try http://www.bonavolta.ch/hobby/en/audio/audioel.htm
SE = single ended, PP = push pull.

Also try doing a bit of googling for FAQs, save you a bit of time!
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Old 7th August 2003, 01:03 PM   #10
weirdo is offline weirdo  United States
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whoa sorry if i'm impatient- just haven't had much luck at all at other forums and figured that that is what was happening here too. sorry
Now that's some info i need! a kit would be good,yes,but i prefer to find out as much as i can BEFORE building this type of stuff that way hopefully i can continue thru problem after problem,instead of stopping for days at a time to r+d then work then r+d and so forth. i know i won't learn everything so some r+d will be needed -i just like to tackle things while being very informed. and...if i can learn something and i've got most of the parts already and i'm on one helluva tight budget,why not just spend alittle and make it a lot. Thanks ShiFtY! i will set my attention on that site you gave-thanks!
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