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balanced input stage

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diyAudio Senior Member
Joined 2002
Hi,

take unbalanced output from one of the plates.

Since both plates will present an amplified signal with opposite polarity with respect to its input, choose the one you require.

Something like this:

Cheers,;)
 

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grataku said:
Sounds cool! Can you give more details?

Pretty simple. Basically just the use of a step-up transformer coupled to a voltage follower.

There are some practical limits however so you're looking at a rather low power amp. The one I've been working on is about 8 watts. Not that that's necessarily the upper limit.
 

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Just the opposite of a phase splitter: feed the balanced signals to the respective grids (remember, the circuit acts like an op-amp with very limited gain) and take unbalanced output from one of the plates.

yeah.. it's kinda obvious isn't it! i kinda thought this, but i wasn't really sure at all, so thanks for your help... too bad i don't know the purpose of an op-amp though... i'm not really very knowledgable in the world of SS devices... actually, i really have no idea... maybe once i leave school and am being a bum next year, i will dedicate some time to learning about SS... but for now, i dedicate my time to tubes...

cheers
 
where do i find out about this type of circuit then??? i want to find out...
i know ignorance is no exuse, but i guess i should be excused for my ignorance seeing as i'm just a kid... i only thought opamps were a SS device because that's the only area of electronics i ever hear of them... do you forgive me for this sacrelige?:scared:
just one more thing based on my own ignorance... "Ahhh, grasshopper"
what's the grasshopper thing?:confused:

cheers:)
 
Sorry, it was a cultural reference suitable for someone about twice your age:D

Anyway, the classic texts on vacuum tubes (e.g., Terman, Radiotron, Valley and Wallman) all have very deep explanations of tube op amps and their internal workings. To just get the principle of how an op amp works as a functional block, Horowitz and Hill is an excellent start, as is Walt Jung's book on op amps.
 
I'm sure some of the more knowlegable board members could do better, but try Operational Amplifier Basics by Harry Lythall, for starters.

They do, of course, come mainly packaged in Silicon, but it is possible to build one out of tubes, too. The silicon variety have a not-so-good rap within the high-end audio community (especially when compaired next to a good tube stage!), though more recient incarnations have imporved very much sonically over their earlier bretheren. Junji Kimura even reckon'd that they were more fun to play around with than tubes, though I'm not sure quite agree! ;)


{Edit: SY is right; Mr. Jung (no relation to Carl ;) ) is considered one of the preeminant dudes on Op-Amps

PS: I guess I'm showing my own age too since I loved Kung-Fu :) }
 
hi sy,

do either the RCA-10 or RCA-13 manuals explain these??? i have these two, and had a quick browse, but didn't see anything on them as either op amps, or operationsal amplifiers... but that was just a quick look... i'll look more closely.

thanks for those links majestic, will read soon.

cheers
 
thanks sy.

what do you think of the radiotron designers handbook??? will this have it... and what do you think of it in general? is it a worthwile manual to have?

just asking because i was already planning on purchasing this (on CD version as this will only cost $60 aussie, i could not justify the cost of hardcover for my uses).

cheers
 
oh well, looks like a good idea i had then... i thought it was in the first place. i've already heard that it's suposedly good, and i thought that at somewhere around 1500 pages, there's gotta be something good in it... and for only $60... and then after what you said. it will have to be sometime in the near future though, as atm i am in debt. :(

cheers
 
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