Siemens V275D wiring like microphone preamp

Hi..Can someone help with wiring 275d in microphone mode..Impedance on input is 4k (put in series resistor 600ohm??)
Also its not clear how to wire potentiometer..How to get maximum gain..
This is two channels input amplifier with summing to mono out..
On german vintage audio rentals there is modded to 56db,

There is other part of schematic..

Wiring diagram..I can not understand how to wire  potentiometer its on same pins of input??I am planning to use like  one channel input,I will not use for summing two inputs channels..thanks in advance

There is link to modded v275D..
http://www.vintageaudiorentals.com/de/artikel/vintageaudio-75.html

I don't see any obvious way to make a lot of gain from that circuit.

What is V275D supposed to be used for?

It provide +24db  with proper wiring,I can not get that gain because  need 10k pot  I am not sure how to wire pot ..Its good for loud sources like kick.snare etc..I do not know in which scenarios is used..Its universal amp

You're talking about the 10K trimmers drawn on the connector?

If you want max gain, then do not use the pots at all. They are just attenuating. So connect XLR pins 2/3 -> 6/8 or 12/10.

Image 6.jpg in Reply #1 is not working. If there is any voltage gain in this thing, it is in the missing image. Re-post.

Already I wired two inputs in series and getting amplification almost doubled..You are right pot is attenuator(its not feedback resistor)..Is there option like in other siemens sitral modules like V272 v275  wire somewhere to control amplification..Already today wired v275-01 with R1 and R2 removed and pot wired across C3 (100K)and I am getting about 50-60 db..

there is again image 6..

I'm not familiar with those modules. I'm just looking at the schematics you posted.

You might try flipping the input transformer around. Looks like 18dB there (err ... 36dB change?). Might be an easy thing to try. With a zobel.

ljupcopavlovski said:

Its universal amp

Click to expand...

No. It is a dual summing amp.

V = Amplifier family
V 2xx = Siemens Sitral
V x75 = Summing Amp
V 275 D = Dual Summing Amp

ljupcopavlovski said:

....Is there option like in other siemens sitral modules like V272 v275  wire somewhere to control amplification..

Click to expand...

Replace R33 with 10k pot and try it. Pozdrav 

Thanks  buddy!! Its work with changing  R33 with 10k pot..I am getting about 50-55db..Hvala ti druze..

It is a 2-input mixer (not what I would call a summing amp). It probably takes two line-ins and drives a line/bus.

Yes, up-sizing R33 will raise gain.

Noise may not be great. TS1 TS2 is unity gain, and then R23 R24 mix has loss of 2. (Also R17 R20 but I assume you set them at max.) It is not clear to me what the input transformer is, but taking 4K on one side and 160K on the other it is liable to be 1:6. Likewise I am not familiar with "+6dB on 300r" output, but clearly that output transformer is low ratio.