Suitability Of Lundahl 1538 As A Mic Output Transformer

[rodabod]

Does anyone have any opinions on using the 1538 as a mic transformer? Obviously Jakob thought it would work well for the G7 and people seem to be happy with that.

I'm looking for a transformer for my Thiele valve condenser mic which I will be building a Russian plate-out circuit into which will suit a 5:1 output transformer. Along with the M7-ish capsule and interesting grill design, I'm not sure how it will sound.

So, I'm mainly interested in the transformer's technical performance in this role (does anyone know how many Henries it should provide? Lundahl don't offer much specs. in that regard). If I don't go for this option, then I'll probably stick with a fancy model from Sowter, but I thought I might try this route first.

Cheers,

Roddy

 

[ioaudio]

mic plate out transformers from the classics are in the area 50 - 100 Henry on the primary, depending on the Z out from the tube.

additionally the transformer and the coupling cap form a LC circuit. e.g. u47 about 50 henry coupled with 0,5µF - results in a low resonance point of 31.8 Hz.

many new transformers are over-designed: more henry - lower cutoff point.
a nice example for this is on the cinemag page. technically better, but (for many) not better sounding.