[piedpiper]

I'm thinking about modifying the input of my Trumpet from single ended to balanced using the existing RCA jacks in combo with the ground screw by disconnecting the jacks from chassis ground and connecting the ground of the jack to the input of R39/77. I know there is alot of controversy about what this might mean, but wonder what advantage it might have. Would I then have to insert a second 47k load resistor to ground before R39/77 or would I need to double or half that value as well as that of the existing load resistor in order to maintain a 47k load. If I wanted to lower the loading to say 50 ohms would I need to lower the value of the 220 ohm R19/60/41/77 input resistors in order to accomodate this?

[hagtech]

It is possible to make the inputs differential.  Yes, one side needs 47k for proper impedance balancing (Ok, theoretically they should both be 23k, but it's not a big thing).  Right now it goes to GND via 1 ohm resistor.  The jacks are already lifted from GND.  For other loading, just put a resistor across the inputs in parallel with the 47ks.  Or you can put the 50 ohms right on the cart.  No change to the 220 ohm grid stoppers necessary.

I doubt you will find any benefit.  Best to use triaxial wiring.  That is, twisted pair signal inside a grounded shield.

jh

[piedpiper]

Thanks again. The schematic doesn't mention the 1 ohm resistor. I may be going with a step up of some sort whether iron or Piccolo which will make the loading a non issue but I might try to get by without it as I'm on the edge of workability at the present gain, lacking a bit of oomf though I suspect. I had triaxial already in mind.