Dual-jFET 2SK146 and two single jFETs 2SK147 in parallel Operation in Luxman's L550

[tiefbassuebertr]

This I have never see before. The dual jFET 2SK146 is mounted from the component side, while the additional types 2SK147 soldered on the solder side.
What could be the goal of the idea, each half of a dual jFET a single jFET connected parallel (without additional source resistors) by the input differential cascode stage of Luxman's integrated amplifier L550?

In the schematic diagram this parallel mode of different jFETs isn't mentioned - go to
http://www.hifiengine.com/manuals/luxman/l-550.shtml

[wahab]

According to the schematic , the 2SK147 are used in the power amp front end
while the 2SK146 are for a RIAA preamp.

There can be some confusion as theses parts , i.e , power amp and RIAA preamp,
both use the same schematic.

There is no paralleled devices unless the amp was modded.

[ticknpop]

Parralled devices would lower noise - does it look like a factory mod or add- on by previous owner? Possibly hard to tell.

Very nice parts if they work , extremely hard to find if they don't . 2sk369 from Zhou Fang is 2sk147 substitute in a lower dissapation package - get extras NOW to make up matched IDSS uads and spares while they are available and affordable. The pictures show 2sk 246 as BL
and V gain groups while the 147'are GR - not a good idea to mix diffferent gain groups especially if there are no source resistors. Zhou Fangs are BL I think.