SR45 amplifier

[braubeat]

Here is the exo-45 hookup data

http://www.audioasylum.com/forums/magnequest/messages/4679.html

Michael

[howardnair]

ok so the side with the large resistance is the primary side-the exo45 is handwritten--but there are no dots-on the primary side both red and blue come out of the transformer at the same distance from the coil--on the output side one wire obviously comes from the inner part of the coil-i will post on the mq site thanks--howie

[johnsonad]

The dots are used on lug connections. You have flying leads.

[howardnair]

aaron -thanks-i should know these things by now-i still am not certain what lead goes where-i suspect that the red to the plate and blue to ground and clear to positive and black to neg-being they are 550 for the pair i would like to be certain-i am surprised how much real estate i need for this-output transformer,large plate choke, triad power choke,grid choke and output trannie times 2 -i am using jensen radial style caps which are large -a mundorf m-lytic cathode bypass cap-again times 2 -plus all the other things needed-rt now it is all layed out on 1 piece of poster board-i am not sure whether it will be 1 amp or 2--this is my first scratch build-so it is fun but i am a little nervous-if put on one chassis are there any special cautions between the left and rt sections-

[johnsonad]

It's best to ask MQ questions in the MQ forum or email Mike directly if you are not sure.

[Paul Joppa]

My mnemonic is the "blue plate special" - an old diner term that has stuck in my head. Blue to the plate (i.e. high AC signal voltage). For series feed transformers the red goes to the high voltage supply; for parallel feed it goes to AC ground; in this circuit that would be the cathode. There is a parafeed cap in one of these lines of course! Note that whether the red lead goes to B+ or to ground, the important thing is that it has near zero AC signal voltage.

[Grainger49]

Paul,

From what I know of transformers it will work either way but swap absolute phase on the output. 

However, wiring it as it should be yields lower noise. 

Is that right?

[Paul Joppa]

I don't know all the reasons for choosing a polarity, but I'm pretty sure there are more than one.

[howardnair]

ahhh!!-Paul--the blue plate special it is!!-mike got back to me and the blue goes to the plate and red to ac ground-and black is ground on the secondary-and here is a little read on the blue plate special

http://en.wikipedia.org/wiki/Blue-plate_special

[Grainger49]

Howard,

Now Paul should reveal what BPC stands for. 

He has before, it isn't a secret but it is funny and appropriate.

[johnsonad]

You mean the Brainiac Plate Choke? I wish Mikey would make a run of them.

[Grainger49]

YUP!   


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[Paul Joppa]

Haha! I acquired that nickname back in the old VALVE days when I would work out operating points in my head. I don't think anybody has used it in the last 10 years though. :^)

[Doc B.]

Nowadays we call Peej "I'llbebackwithananswerafterathoroughanalysisiac", and the products have improved vastly because of it. But it's kind of a crappy name for a choke.

[howardnair]

well!-it being a choke it is a form of audio-erotica