Why G7 signal run thru the negative pin of the LL1538 ?

? :?

http://www.lundahl.se/pdfs/datash/1538_8xl.pdf

in the jakob pcb, i can see that the signal run thru
the pin 5 and the pin 6 & 8 are connected to the ground

why the signal doesn't run thru the pin6 and the pin5 & 8 are
connected to the ground ??

:roll:

Hi jazzy,

there's no "absolute" phase on a LL1538. Reversr phase on the input, the output also reverses.

If you used pin6 as +, the mic would be out of phase (or you could claim it to be an "USA" model, pin3 hot)

Jakob E.

thank you ! :grin:

Sometimes it can make a difference where you ground the secondary.
Transformer makers spec out which leads they want as the low side, which in some circuits, get grounded.
If you ground the correct terminals on the pri and sec, you get zero capacitance between coil sections. This is because both "hot spots" on the windings are now at the same potential, so there is no capacitance.

You can reduce capicitance by grounding just one part of the transformer, which is usually the secondary. But you have to ground the "hot spot" on the secondary, otherwise, there are no benifits.

I don't know if this would apply to the 1538 as I have never been inside one.
Anybody try an amorphous core for the G7?
Might be interesting. Don't know if they make an appropriazte model.


:guinness:

Yes, several of the Lundahls are spec'ed for particular phasing to acheive best results.

The 1538 is not - and I can't detect any polarity difference..

Jakob E.