Hello everyone,

Long time lurker here, first of all thanks for this beautiful forum for both help and inspiration!

I need your help in a preamp schematic which was reverse engineered, but first a little history....I found it near a dumpster and since I felt sorry for it (especially since it seems someone's handwork/modified commercial work) I decided to restore it.

Here are some pics:

https://freeimage.host/i/Ja6MswP
https://freeimage.host/i/Ja6MLt1
https://freeimage.host/i/Ja6MP9V
https://freeimage.host/i/Ja6MiAB
https://freeimage.host/i/Ja6MZoF
https://freeimage.host/i/Ja6MDPa
https://freeimage.host/i/Ja6MtMg

The amp section is a quasi complementary AB class amplifier with two NPN 2N3055 (common for the 90s/00s here if not earlier in Croatia) but that is not of significant interest to me as it is rather simple, the VU meter and speaker delay pcb are also simple and not of interest right now, the interesting thing to me is the preamp section (in order to determine switch and pot functions) which when reverse engineered showed that it used a parametric EQ as shown in the schematic can anyone confirm my suspicions on the pot functions? also there is a omitted cable and a hole in the front plate in the schematic is at the output of the preamp section with a voltage divider is this possibly a recording out thing?

Here is the schematic of the preamp section:

https://freeimage.host/i/pojacalo-100w.Jl9rf4t

Thanks in advance!!