Unusual phono circuits in McLaren preamp

[aussievintage]

In the DIY thread I mentioned a McLaren amp I was fixing up.  Before putting the McLaren preamp into service I spent some time looking at the schematic.  The main preamp is two CA3100 opamps.  The phono cuits are much more interesting.  I'd be interested in hearing opinions or just more info on these circuits.

 

The MC headamp is an unusual configuration of two transistors. A common base amplifier ...

 

 

the power supply is regulated by 741 opamps from the main preamp supply

 

 

The actual RIAA eq preamp is all disctrete transistors, again in an interesting arrangement.

 

 

 

 

Lastly the MC headamp and MM signal inputs to this RIAA preamp each have switched FETs, like this arrangement - not sure the intent of this, other than slow switch/ fading in of the signal.  

 

 

old SS tech, but still interesting to me.

 

 

 

 

Edited November 8 by aussievintage