Question about adding an line/interstage transformer to an existing circuit

[Vyvyan]

I have 2 Yamaha pm-400 mixers, nice little discrete guy full of transformers apparently used by the stones live for bass or something in the 70s/80s schematic is attached. I noticed when switched to line in the signal goes thru the mic input transformer straight to the 10k monitor pot into the bax EQ.

I have plenty of 10k:10k transformers and was wondering if I could possibly use them here, so line in would bypass the mic transformer and go straight to a 10k transformer with the 10k monitor pot on the secondary or would I need some different kinda termination for the transformer also thinking if I can work that out also using the transfer as an interstage between the mic pre and EQ when using the mic input or DI (which I have on a switching jack between mic xformer and mic pre)

Also I'll possibly find a way to use the output amps from my other pm-400 to drive some more transformers for direct out options for each channel

 

[Newmarket]

What us the motivation to put one as interstage between mic pre / DI And EQ ?
Caveat: I may be misunderstanding what you propose without a diagram to clarify.

 

[Vyvyan]

I mainly want to use it as a line input instead of going thru the mic transformer then bypassing the mic preamp straight to the EQ as the mixer is stock in line mode. I figure if I'm adding a line transformers straight to the EQ might as well use it as interstage as well, wouldn't I be able to lose the coupling cap that way? Ill mainly be using it with an 8 track 1 inch machine. I like color. Not very interested in transparent audio

 

[Newmarket]

I see. What is the current input transformer - turns ratio, design impedances ?

 

[Vyvyan]

I see. What is the current input transformer - turns ratio, design impedances ?

600:3k. So around 1:2.2 ratio. As you can see the stock circuit in "line" mode (-20) the mic preamp input goes to ground and transformer secondary has 3.2k going to ground and it's signal is sent to the monitor output pot then into the EQ

 

[Newmarket]

Okay. fwiw I missed the decimal point on the "2.2K" - making it look a bit odd to me. Emphasises why we should always go with format 2K1 etc.
What 10K:10K transformers are you looking to use ?

 

[Vyvyan]

I have an opamplabs t10k and line transformers from a sony mxp2000 console

 

[Newmarket]

I'm wondering whether you'll need overall shielding there. But good luck for the result.

 

[Newmarket]

Did you progress any further with this ?