Neumann PV 46 gain switching questions

[David_H]

Greetings folks!

I have a pair of the old Neumann PV 46 coming my way, and going through the schematic I was wondering about a few things with regard to the gain switching options on this pre.
To start with, the PV 46 has 46db of gain available, with an input impedance of 2,5kOhm - not bad in my book! The 46db gain setting is achieved by reducing the Feedback Resistor to 22 Ohm.
So here's the question: Would it be safe to reduce that value to 0, to coax out a few more dB, without negatively affecting performance?
Thank you for the help, the schematic I am working with is attached.

Best regards,
David

 

[Michael Tibes]

...and while we're at this device: can someone explain, what the outer secondary windings of the output transformer do (around R34/C15 and R35/C16)? Magnetic / transformer 'feedback' ??
Also: what are the asterisk marked links on the connector for (pin 13/14, 15/16)? The schematic says 'for B-operation only. Would that be 'Battery'? Or 'class B', less power consumption, more distortion? All wild guesses on my end...

Thanx,

Michael

 

[Michael Tibes]

Also: what are the asterisk marked links on the connector for (pin 13/14, 15/16)? The schematic says 'for B-operation only. Would that be 'Battery'? Or 'class B', less power consumption, more distortion? All wild guesses on my end...

The probably slightly older version PV46SD (https://gyraf.dk/schematics/Pv46.gif, different copy attached) has the option to switch between a max output level of +21dB into 600 or 200 ohms. Could that be 'B-operation'? This uses different pins on the connector though. Headscratch... I wish I had a descriptive manual for these.

Michael