pri. impedance vs. sek. impedance

[tyor]

I wonder if i use a 8ohm speaker on the 4ohm tapping of a OPT that have 2.5k pri. wil that give me 5k pri impedance?

[jane]

Yes.

[kathodyne]

yes, it will.

[tyor]

thanks.

[Empee]

Hi!

Can a PP opt be used as a SE opt ?

if so, use one-side-to-centretap or use the whole primairy ?

I got a PP opt Ra-a of 1K7, how much would one side be ?


cheers,

Empee

[AndreasS]

Hi Empee,

yes, but without DC in the primary. Use both sides of the primary connected in series.

Regards Andreas

P.S. using only one side you'll get 1/4 of the inductance

[Empee]

how do you mean that, without DC in the primairy ?



and just to be sure:

In series, so leave the centretap unconnected.

Primairy remains 1K7.

If 8 ohm speaker used on 3 ohm tap primairy acts as 5.1K

EL34SE ?

[AndreasS]

Originally posted by Empee
how do you mean that, without DC in the primairy ?

A choke betwen the plate of the output tube and Ub+ and a blocking condenser betwen the plate and the output transformer primary, the second connection of the primary to earth.

Originally posted by Empee Primairy remains 1K7.

If 8 ohm speaker used on 3 ohm tap primairy acts as 5.1K

EL34SE ? [/B]

only in the mid-frequencies; for lower frequencies the primary inductance is important.

Regards Andreas