Single voltage powered Tone Control

[elctronn]

Hi, I'm new here.

Please, advise to me, what is the meaning of these parts:

An externally hosted image should be here but it was not working when we last tested it.

Can be used VR1 10k ?
And what is your opinion about this preamp?

Thank you for your help.

 

[DF96]

My guess is that the components you have circled provide a simple 'loudness compensation' so the tone is altered according to the volume setting. Very common at one time on mid-fi stuff but generally avoided in equipment aiming at good sound quality.

My general opinion is that this looks like early 1970s mid-fi.