Hej igen.
Jeg har været i kontakt med en flink fyr i Tyskland, Aaron, der har givet mig lidt info omkring de her LL5402 trafoer.
Her under er hans svar omkring configurations mulighederne. -I tilfælde af at andre, sidder med lign. tanker...
The LL5402 primaries must be
series and secondaries
parallel to have a 1:1 configuration because the winding are different on both ends... Well, the thing is, you have a few options. If you swap input / output you won't have an impedance issue in most cases, but you can play around with it for 2:1 or 1:2 configurations without adding a pad or increasing the volume by other active components.
Usually if you have the 1:1 configuation, it should not make a different... but in some cases it does because the LL5402 has different windings and your gear looks at a high or a low impedance first...
As test, if you have a proper 1:1 configuration, you should not hear a loudness difference if you go into the trafo... if you hear a loudness difference, you might have to swap input/output because one of the windings is parallel and the other side series to get the ll5402 1:1.
A general purpose 1:1 trafo has two same windings and it does not make a different if you go into the input (primary) or output (secondary) because it´s 1:1... but this would be to easy
Jakob who developed this GSSL Gainstage also used the LL5402 for his GPULTEC in a similar way the PCB can be configurated. The only complicated thing is to understand that the LL5402 must be wired parallel for the secondary get the 1:1 style. There is more wire on the secondaries which would result in a 1:2 stepup configuration if you would make both sides in series. On the Don-Audio PCB the 1:1 config is series/parallel
and the 1:2 config is series/series.... so completely the opposite like with a general purpose 1:1 trafo which is series/series = 1:1.
